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Speaking valves in tracheostomised ICU patients weaning off mechanical ventilation - do they facilitate lung recruitment?

Speaking valves in tracheostomised ICU patients weaning off mechanical ventilation - do they... Background: Patients who require positive pressure ventilation through a tracheostomy are unable to phonate due to the inflated tracheostomy cuff. Whilst a speaking valve (SV) can be used on a tracheostomy tube, its use in ventilated ICU patients has been inhibited by concerns regarding potential deleterious effects to recovering lungs. The objective of this study was to assess endexpiratorylungimpedance (EELI) andstandard bedside respiratory parameters before, during and after SV use in tracheostomised patients weaning from mechanical ventilation. Methods: A prospective observational study was conducted in a cardio-thoracic adult ICU. 20 consecutive tracheostomised patients weaning from mechanical ventilation and using a SV were recruited. Electrical Impedance Tomography (EIT) was used to monitor patients’ EELI. Changes in lung impedance and standard bedside respiratory data were analysed pre, during and post SV use. Results: Use of in-line SVs resulted in significant increase of EELI. This effect grew and was maintained for at least 15 minutes after removal of the SV (p<0.001). EtCO showed a significant drop during SV use (p = 0.01) whilst SpO remained unchanged. Respiratory rate (RR (breaths per minute)) decreased whilst the SV was in situ (p <0.001), and heart rate (HR (beats per minute)) was unchanged. All results were similar regardless of the patients’ respiratory requirements at time of recruitment. Conclusions: In this cohort of critically ill ventilated patients, SVs did not cause derecruitment of the lungs when used in the ventilator weaning period. Deflating the tracheostomy cuff and restoring the airflow via the upper airway with a one-way valve may facilitate lung recruitment during and after SV use, as indicated by increased EELI. Trial registration: Anna-Liisa Sutt, Australian New Zealand Clinical Trials Registry (ANZCTR). ACTRN: ACTRN12615000589583. 4/6/2015. Keywords: Mechanical ventilation, Tracheostomy, Communication, FRC, Speaking valve, Lung recruitment * Correspondence: anna-liisa.sutt@health.qld.gov.au Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia School of Medicine, University of Queensland, Brisbane, Australia Full list of author information is available at the end of the article © 2016 Sutt et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Sutt et al. Critical Care (2016) 20:91 Page 2 of 9 Background measure EELV but current time-differencing systems rely Invasively ventilated patients are unable to phonate due on measuring the difference between end-inspiratory lung to either the endotracheal tube positioning through the impedance and EELI to measure tidal variation of imped- vocal folds, or when ventilating through the tracheos- ance and changes in EELI [12]. There is linear correlation tomy, the air bypassing the vocal folds. Speaking valves between changes in the EELI and changes in EELV [15–17], (SVs) can be used in-line with mechanical ventilation, although this relationship tends to overestimate changes but use of these requires deflation of the tracheostomy in EELV [16]. A limitation of time-differencing EIT is that cuff [1]. Cuff deflation causes a leak in the ventilator cir- it is unable to detect the pre-existing EELI [18, 19], which cuit, which has been considered detrimental to patients’ means it can only detect changes in EELI if the device re- ventilation, and potentially deleterious to weaning. mains in situ and running between readings [15, 18–20]. The key concern raised by physicians is that by deflat- Researchers, however, have successfully used EIT to de- ing the cuff, and thus, losing positive end-expiratory tect changes in EELI due to various clinical interven- pressure (PEEP) this could lead to loss of lung volume tions such as suctioning, position change, and changes through alveolar collapse. It has been demonstrated that in PEEP [13, 16, 20–23]. loss of PEEP in other events such as suctioning [2, 3] The aim of this study was to assess the effect of SVs and ventilator disconnection [4] causes loss of lung vol- on EELI. Based on the findings of prior case studies it ume. Current data indicate that “open lung ventilatory was hypothesised that there is an increase in global EELI strategies” minimise ventilator-induced lung injury [5]. with the SV in situ when patients are performing trials Hence, practices that may cause loss of lung volume off the ventilator (i.e., on 50 L of 40 % oxygen via the must be used with some degree of caution. tracheostomy). This may potentially be similar when pa- One small case series has described the apparently safe tients are constantly supported by mechanical ventila- use of SVs during weaning from mechanical ventilation tion, given restored physiological PEEP. Secondary aims [6]. Another study found no significant difference in included determining the effects of SV on the patient’s ventilator weaning and decannulation times post the respiratory rate (RR), heart rate (HR), oxygen saturation introduction of in-line SVs into an adult intensive care (SpO ) and end-tidal carbon dioxide (EtCO ). The po- 2 2 unit (ICU) [7, 8]. Whilst these studies provide prelimin- tential effect on respiratory mechanics of talking versus ary clinical support for use of in-line SVs with tracheos- quietly breathing with the SV in situ, and the effects of tomised mechanically ventilated patients, there are no the SV and its dependence on the patients’ ventilatory physiological data to prove or allay fears. requirements at the time, were also investigated. Currently there are no data on the effect of SVs on end-expiratory lung volume (EELV), a critical point Methods when the lungs are at most risk of collapsing. An SV is a Following human ethics approval by the Institutional one-way valve that allows for inspiration via the trache- Review Board (HREC/13/QPCH/95) a prospective obser- ostomy tube whilst expiration is redirected to the upper vational study (ACTRN12615000589583) using a repeated airway via the vocal folds, enabling phonation [1] and re- measures design was conducted. The study took place in a stored upper airway resistance. Hence, it can be consid- primarily cardiothoracic ICU at a metropolitan tertiary ered functionally as a PEEP valve on the tracheostomy. teaching hospital. Consecutive patients who were tra- As there is no airflow back into the ventilator tubing cheostomised and being weaned from mechanical ventila- with the one-way valve, current in situ monitoring of tion, from November 2013 to December 2014, were ventilation with standard bedside equipment provides considered for inclusion in the study if they were tolerat- the clinician with limited information on ventilation. ing a SV for a minimum of 30 minutes, as jointly assessed While computerised tomography or magnetic resonance by a speech pathologist and a physician. Patients were ex- imaging may be able to provide this information, the re- cluded if they had significant language or cognitive defi- peated use these imaging procedures could be seen as cits, or were not suitable to wear an EIT belt (i.e., patients ethically unjustifiable, expensive, possibly requiring a with ventricular assist devices, open chest, extensive level of sedation, and putting patients at risk with the sternal dressings/drains or those dependant on cardiac transfer outside of the ICU environment [9, 10]. pacing). In total 20 patients were recruited into two Electrical impedance tomography (EIT) is a radiation- groups: 1) 10 patients on pressure support ventilation free real-time bedside imaging tool capable of measuring (PSV) and 2) 10 patients having trial periods off mechan- the air movement in and out of the thorax [11–14]. It ical ventilation (and transferred onto high-flow or low- has been observed as being a safe, reliable and reprodu- flow oxygen via the tracheostomy). All patients provided cible technique to assess regional ventilation in the lung, written informed consent, or for those unable to sign for specifically during recruitment manoeuvres [3]. In the written consent, the consent was provided by a legally future it may be possible for absolute EIT to directly authorised person (e.g., family member) or by the patient’s Sutt et al. Critical Care (2016) 20:91 Page 3 of 9 nurse witnessing verbal consent. The study was conducted adapter that accommodated the EtCO /P catheter. Ven- 2 aw in accordance with the ethical standards laid down in the tilator settings were changed while the SV was in situ in 1964 Declaration of Helsinki. the patients supported by pressure support ventilation (PSV). This included switching the system to non-invasive Measures (NIV) mode for PSV (to more easily control expiratory Following informed consent, patients were enrolled in alarms) and reducing the set ventilator-delivered PEEP by the study. EIT (Pulmovista, Draeger Medical, Lubeck, 5cmH O [25]. This change in settings was based, in the Germany) measurements were taken continuously for absence of any scientific data to define optimal settings, 60 minutes with the frame rate set to 10 Hz to give the on recommendations by the SV manufacturer. During the EELI per breath. Transitions to and from SV were followed second data collection period patients were instructed to by 15-minute periods, to allow for stabilisation [24]. continue to breathe normally and avoid talking. Once the Set ventilator-delivered PEEP and fraction of inspired third data collection period commenced the patients were oxygen (FiO ) data were collected from the ventilator instructed to converse as they wished with the researcher, (Puritan Bennett 840, Covidien, Dublin, Ireland). HR family member, or healthcare team. When verbal commu- and SpO were measured with pulse oximeter (504, Cri- nication was limited, the researcher used picture cards ticare systems, Waukesha, WI, USA). Airway pressure and open-ended questions to facilitate verbal output. As (P ) was measured directly via a neonatal feeding cath- there is a suggested difference in breathing patterns be- aw eter (6 F) introduced through the Luer port of an tween different speech tasks (planned vs non-planned) adaptor (Ikaria, Hampton, NJ, USA) advanced to lie just [26], no set tasks were given to participants, and spontan- distal to the tracheostomy cannula in the trachea, and eous speech was encouraged. At the completion of period measured with a pressure transducer (PPT, Honeywell, 3, the ventilator settings were returned to baseline, the SV Morris Plains, NJ, USA). Oximeter and pressure data was removed, and the tracheostomy cuff re-inflated. Data were collected at 200 Hz (PowerLab, AD Instruments, collection continued in the fourth period as per baseline Sydney, NSW, Australia). EtCO was sampled from the conditions. Routine tracheal suctioning was performed feeding tube and measured (Marquette Solar 8000, GE during data collection as per individual patient needs. Healthcare, Little Chalfont, UK). EtCO was measured continuously throughout the 60 minutes apart from 2 Data analysis minutes before, during and after SV use when continu- Data were analysed offline post data collection using ous P measurements were taken through the same commercially available Draeger software (Draeger EIT aw catheter. There was no flow through the catheter during Data Analysis Tool 6.1). EELI was averaged across the pressure measurements, to ensure highest possible fidel- readings and displayed as mean EELI for each of the ity. All data were collected on a breath-to-breath basis four data collection periods. A mixed effects regression using custom-written software. model was used to investigate the changes in EELI com- pared to baseline. Planned comparisons between base- Procedure line and each subsequent data collection period were The patients were positioned either in bed at 45 degrees conducted using the paired t test, for RR, EtCO ,HR or in a straight-backed chair with the EIT electrode belt and SpO . The level of significance was set at p <0.05 around their chest at the level of the fifth to sixth anter- throughout, with 95 % confidence intervals quoted where ior intercostal space. As patient position has been shown appropriate. All statistical analyses were conducted using to have an impact on ventilation distribution [13], we STATA (version 12.0). TM ensured that there were no significant changes in patient positioning throughout the data collection. A neonatal Results feeding catheter was inserted as described above and the During the study period 55 tracheostomised patients pulse oximeter was positioned on the finger. used an SV, and all were assessed for inclusion in the Fifteen minutes of data were recorded continuously study. Of these patients 20 met the inclusion criteria and during four discrete periods: (1) baseline – prior to were enrolled in the study. Figure 1 details the reasons placement of the SV in-line with mechanical ventilation; for exclusion or non-participation in the study. (2) quiet breathing with SV in-line; (3) talking with SV The mean age of the patients in the study was 60.4 ± in-line; and (4) post removal of the in-line SV. After the 14.9 years (50 % male). The mean age for all tracheosto- baseline period the tracheostomy cuff was deflated with mised patients in the ICU throughout the recruitment simultaneous tracheal suctioning to clear secretions period was 57.1 ± 17.4 years (64.6 % male). On average, pooling above the cuff and minimise aspiration. The SV patients used an SV for 2.5 days prior to recruitment to (PMV007, Passy Muir Inc., Irvine, CA, USA) was then the study. There were 10 patients assessed whilst being inserted in-line with the ventilation circuit following the ventilated with PSV, and 10 assessed during periods off Sutt et al. Critical Care (2016) 20:91 Page 4 of 9 Fig. 1 Participant selection chart. SV speaking valve, BiVAD biventricular assist device, EIT electrical impedance tomography, LVAD left ventricular assist device, PMSV Passy-Muir speaking valve, PPM permanent pace maker the ventilator (9 on high-flow, one on low-flow oxygen) were seen in data collection period 3 and 4, respectively for the duration of data collection. All but one of the pa- (see Fig. 2 and Table 3). tients who were assessed off ventilator were still requir- Of note, patients’ ventilatory requirements at the time ing >12 h/day of mechanical ventilation. See Table 1 for of recruitment did not have a significant impact on the specifics of respiratory requirements. The majority change in EELI, any of the respiratory parameters or of patients (17) had their tracheostomy tubes inserted HR. The patients who were supported on PSV during percutaneously in the ICU. Primary reasons for ICU ad- data collection had an initial non-significant drop in mission included cardiac surgery (n = 13, 65 %) or re- EELI. However, a similar increase in EELI with patients spiratory disease (n = 5). Nineteen of the patients (95 %) off the ventilator was noted for the third and fourth had received a tracheostomy due to prolonged need for period of data collection (see Fig. 2). mechanical ventilation. Patient number 3 had the trache- EtCO decreased significantly during SV use (p = 0.02 ostomy initially inserted for surgery in the upper airway, for period 2 and p = 0.01 for period 3) and returned to but required prolonged respiratory support following baseline for period 4. RR decreased significantly from cardiac surgery. See Table 2 for a more detailed descrip- baseline while SV was used in-line with the ventilation tion of all patients in the study. circuit (p =0.001, p <0.001 for periods 2 and 3, respect- A statistically significant increase in EELI was ob- ively), and returned to baseline once the SV was removed. served between baseline and all subsequent data collec- HR and SpO did not change significantly throughout tion periods. A mean increase by 19.7 % (213 units) data collection. occurred from baseline to period 2 (SV + quiet breath- Only limited data on P were captured (three partici- aw ing, p = 0.034). Further increase from baseline by 83.6 % pants with full data, seven with partial data). These data (905 units) (p <0.001) and 120 % (1,299 units) (p <0.001) all indicated similar drops in P coinciding with the aw Sutt et al. Critical Care (2016) 20:91 Page 5 of 9 Table 1 Participant ventilation needs actions of the SV) and its deflated cuff, ensuring more residual air in the lungs at the end of expiration. Further Patient number Vent. needs Weaned Y/N PS PEEP FiO Flow analysis is required to confirm that lung hyperinflation 1 HFTP N N/A N/A 40 % 40 L did not occur as it could be argued that an increase in 2 HFTP Y N/A N/A 40 % 40 L EELI may correlate to tidal hyperinflation. We used 3 LFTP N N/A N/A 30 % 5 L SpO2 and EtCO as simple measures to exclude patho- 4 HFTP N N/A N/A 40 % 50 L logical degrees of hyperinflation, but this cannot exclude 5 PSV N 10 5 40 % N/A it fully. Of note, all patients had been using an SV before 6 HFTP N N/A N/A 40 % 50 L the study with no gross signs of hyperinflation on rou- tine chest radiographs. 7 HFTP N N/A N/A 40 % 40 L The subsequent increase in EELI when patients talked 8 PSV N 15 10 35 % N/A is explicable through the additional, but variable, upper 9 HFTP N N/A N/A 50 % 50 L airway resistance caused by the glottis [27] with vocal 10 PSV N 13 10 40 % N/A folds closing and opening during attempts at phonation. 11 HFTP N N/A N/A 40 % 40 L The SV appeared to act as a recruitment manoeuvre. An 12 PSV N 10 7.5 40 % N/A increase in EELI was observed during SV use and its ef- fect remained after removal of the SV from the patient’s 13 PSV N 15 5 35 % N/A ventilation circuit. EELI remained stable for 8–9 minutes 14 HFTP N N/A N/A 30 % 30 L once the SV was removed from the ventilator circuit 15 HFTP N N/A N/A 40 % 40 L and the tracheostomy cuff re-inflated before a further in- 16 PSV N 10 8 40 % N/A crease occurred. 17 PSV N 10 5 35 % N/A There are several potential explanations for the drop 18 PSV N 12 5 40 % N/A in EtCO during the SV use. One reason may be a drop in EtCO due to using one’s voice, as observed in a study 19 PSV N 12 8 45 % N/A 2 of healthy subjects [28]. Another potential reason is 20 PSV N 12 7.5 40 % N/A dead-space washout in the upper airway that has been respiratory needs at point of recruitment. Considered not weaned if needed found in other studies [29, 30] to coincide with an in- mechanical ventilation (Vent.) in the preceding 24 h FiO fraction of inspired oxygen, Flow O flow requirements at point of 2 2 crease in tidal volumes. With our current data, we can- recruitment, HFTP high-flow tracheostomy piece (>30 L/min of O ), LFTP not categorically state, however, that tidal volumes low-flow tracheostomy piece (<30 L/min of O ), PEEP positive end-expiratory pressure, PS pressure support, PSV pressure support ventilation increased for patients in this study. A third potential aetiological cause may be that the exhaled air just past the reduction of ventilator-delivered PEEP for the duration tracheostomy cannula from where EtCO was measured of the SV use. Ventilator data showed that there was was being diluted with fresh inspiratory flow in all patients minimal expired tidal volume when the SV was in-line on high-flow oxygen, and some on PSV while the cuff was (see Table 4). deflated. Transcutaneous carbon dioxide (TcCO )and arterial pressure of carbon dioxide (PaCO ) may need to Discussion be measured in similar studies in the future. The findings indicated that use of SVs in this cohort did Only limited data on P were captured, due to rapid aw not result in any significant de-recruitment of the lungs, and repeated obstruction of the fine-bore catheter with which was contrary to concerns initially voiced by physi- secretions due to presence of no flow through the cath- cians. Standard bedside respiratory data demonstrated eter during the numerous 2-minute measurements. A reduced work of breathing with adequate gas exchange. similar reduction in P coinciding with the turning aw The increase in EELI may indicate increased EELV. Fur- down of the set ventilator-delivered PEEP for the dur- ther analysis is necessary to more fully determine venti- ation of the SV use was noted. However, due to lack of lation distribution, as an increase in EELV could be due data, it is difficult to draw any conclusions. Further stud- to further recruitment or over-inflation of already aer- ies are needed to further look at P and ventilator- aw ated parts of the lung. delivered PEEP with and without an SV in circuit. The increase in EELI with the SV in the ventilator cir- It was surprising to observe that the ventilator demon- cuit is likely to occur through the restoration of the pa- strated substantial exhaled tidal volume whilst the SV tient’s ability to breathe through the larynx and upper was in situ. This may indicate the presence of a leak in airway, as opposed to the continuously patent tracheos- the SV or some form of back-pressure. This means that tomy tube. Upper airway resistance is increased due to the ventilator may actually still be delivering PEEP when the resistance created by exhalation against and around a one-way valve is in place, and will be the subject of the effectively closed tracheostomy tube (through the further studies. Sutt et al. Critical Care (2016) 20:91 Page 6 of 9 Table 2 Demographics and tracheostomy data Patient Age, Gender Primary reason for admission to ICU Days TT Days to Insertion TT type and size Days of SV use number years to SV, n decannulation, n method when recruited, n 1 63 M acute myocardial infarct; CABG 11 18 perc long flange Portex 8 2 2 48 F acute myocardial infarct; tamponade 5 12 perc cuffed Portex 8 6 3 72 F Buccal SCC + CABG 5 7 surg cuffed Portex 7 0 4 71 M tissue AVR for infective endocarditis 2 4 perc cuffed Portex 8 1 5 29 M endarterectomy 2 5 perc cuffed Portex 8 1 6 77 M CABG x3 and mechanical AVR 6 23 perc cuffed Portex 8 1 7 44 F aortic dissection 6 7 perc cuffed Portex 8 1 8 33 F endarterectomy 4 12 perc cuffed Portex 7 4 9 61 M H1N1, ARDS 12 23 perc cuffed Portex 8 8 10 70 M CABGx2 3 5 perc cuffed Portex 8 1 11 70 F cardiac tamponade 4 6 perc cuffed Portex 7 1 12 43 F PE 2 5 perc cuffed Portex 7 2 13 47 F Influenza A ARDS 4 6 perc cuffed Portex 8 1 14 70 F CAP 2 7 perc cuffed Portex 8 5 15 58 M CAP 3 N/A surg cuffed Portex 8 1 16 62 F CAP 2 6 perc cuffed Portex 8 1 17 74 F extensive GI surgery 10 31 perc cuffed Portex 7 7 18 78 M CABG x4 3 5 perc cuffed Portex 8 2 19 60 M chest trauma 7 12 surg long flange Portex 8 2 20 77 M repeat sternotomy for tissue AVR, CABGx1 4 13 perc cuffed Portex 8 2 M male, F female,SV speaking valve, ARDS acute respiratory distress syndrome, AVR aortic valve repair, CABG coronary artery bypass graft, CAP community acquired pneumonia, GI gastrointestinal, PE pulmonary embolism, perc percutaneous, SCC smallcellcarcinoma, surg surgical, TT tracheostomy tube Communication is a key issue for ventilated patients, participate in care [31, 34–36], poor sleep, and increased who find the inability to speak distressing [31–33]. Diffi- anxiety and stress levels [37], which has both short-term culties with communication in the tracheostomised and long-term impacts on patient outcomes in ICU and patient population have been associated with social with- post ICU stay. By demonstrating the potential physio- drawal, leading to depression, lack of motivation to logical benefits on top of the already known and more obvious psychological benefits, SVs present an excellent way to improve patient care in the ICU. Increased use of SV brings with it multiple questions, such as, for how long should the SVs be used at any one time? Does this lead to fatigue? Should the SVs be used with patients during mobilisation? Future studies are needed to look at the efficacy of SVs in the weaning and Table 3 Outcome measures across four time periods Baseline (1) SV (2) SV-talk (3) Post SV (4) SpO 96.5 (0.5) 95.5 (0.7) 94.7 (0.7) 96.0 (0.8) RR 25 (1.6) 22 (1.5)* 20 (1.7)* 25 (1.4) HR 95 (2.8) 95 (2.4) 96 (2.9) 96 (3.0) Fig. 2 Mean end-expiratory lung impedance (EELI) vs time with EtCO 29 (1.1) 27 (1.1)* 26 (1.2)* 28 (1.0) average EELI trend for non-vent and pressure support ventilation EELI, mean 1082 (57) 1295 (61)* 1987 (60)* 2381 (75)* (PSV). Mean EELI is plotted on the y-axis against a nominal time base. A lowess smoothing line has been added to clarify the overall trend. All data are presented as mean (standard error of the mean) *Statistically significant change, p <0.05 non-vent patient off mechanical ventilation during recruitment, SV EtCO end-tidal carbon dioxide, HR heart rate, EELI end-expiratory lung impedance, speaking valve RR respiratory rate, SpO peripheral capillary oxygen saturation, SV speaking valve 2 Sutt et al. Critical Care (2016) 20:91 Page 7 of 9 Table 4 Airway pressure (P ), expired tidal volume (TV) and duration of the study with the patients sitting up. There- aw peak inspiratory pressure (PIP) fore it was not feasible to monitor the patients for Baseline (1) SV (2) Post SV (4) longer. P ,(n =7) 10.5 cmH O 5.6 cmH O 10.7 cmH O aw 2 2 2 b c TV, L (n = 10) 0.550 0.024 0.534 Conclusions PIP (n = 10) 19.8 15.1 20 When SVs were used in this cohort of cardio-respiratory Full data for all three periods from three patients only patients, we observed no evidence of lung de-recruitment Data from all 10 mechanically ventilated patients in the study whilst weaning from mechanical ventilation. Deflation of Two patients had higher TV of 0.106 L and 0.088 L on average, and two the tracheostomy cuff with restoration of the airflow via patients had TV of 0.0 L. SV speaking valve, P airway pressure, TV tidal volume aw the upper airway with a one-way valve facilitated an in- crease in EELI both during and after a period of SV use in rehabilitation process of mechanically ventilated tra- our cohort of patients, which may indicate recruitment of cheostomised ICU patients. the lungs. Use of the SV resulted in reduced RR and a re- duced end-tidal CO . Limitations of the study This study was conducted on a specific cohort of ICU patients, mostly cardiothoracic, and extrapolation of Key messages these data to patients with different pathological condi- tions may not be wise. This is even more relevant in pa-  Speaking valve use facilitated an increase in end- tients with spinal and brain injuries in whom central expiratory lung impedance in tracheostomised control of breathing might be affected. cardiothoracic ICU patients weaning off mechanical No patients in this study were ventilated using ventilation volume-controlled modes, hence there is a need to de-  Increased end-expiratory lung impedance was termine whether restored physiological PEEP through maintained and further increased for at least the SV helps compensate for the leak in the ventilatory 15 minutes post removal of the speaking valve from circuit similarly in volume-controlled ventilation. the ventilation circuit Airway pressures were only measured for the second  Speaking valve use resulted in a reduced respiratory half of the study with limited data obtained as described rate and reduced end-tidal CO when used in above. Hence the reported P data may be a poor rep- tracheostomised cardiothoracic ICU patients aw resentation of the actual P across the time points in weaning off mechanical ventilation aw the study, and was therefore not reported in detail. Dif- ferent methods to obtain these important data are rec- Abbreviations EELI: end-expiratory lung impedance; EELV: end-expiratory lung volume; ommended for future similar studies. Minor difficulties EIT: electrical impedance tomography; EtCO : end-tidal carbon dioxide; also occurred with EtCO measurements (measured in FiO : fraction of inspired oxygen; HFTP: high-flow tracheostomy piece (as all patients in the study) through the same catheter. defined by >30 L of continuous O via tracheostomy tube); HR: heart rate; ICU: intensive care unit; LFTP: low-flow tracheostomy piece as defined by However, due to the presence of airflow in the catheter <30 L of continuous O via tracheostomy tube); P : airway pressure; 2 aw during EtCO measurement, this reduced the likelihood PEEP: positive end-expiratory pressure; PIP: peak inspiratory pressure; of the catheter becoming blocked with secretions, and PSV: pressure support ventilation; RR: respiratory rate; SpO : peripheral capillary oxygen saturation; SV: speaking valve; TV: tidal volume. resulted in almost full data collection across 60 minutes obtained from all patients. Competing interests Routine suctioning was performed as per patient needs AS received financial support (New Investigator Grant and PhD Scholarship) throughout data collection. It is known that tracheal from The Prince Charles Hospital Foundation to conduct the study, and suctioning causes a degree of de-recruitment [22]. The financial support from Passy-Muir Inc. to present preliminary findings of the study at the American Thoracic Society 2015 meeting in Denver. AS is quantitative effect of suctioning was not specifically ana- currently being supported by NHMRC Scholarship. None of the supporters lysed as part of this study, nor were these periods ex- had any involvement in the study design or conduction of it. JFF has cised from data analysis. De-recruitment caused by received grant support from Draeger in previous studies using EIT. For the remaining authors, none were declared. tracheal suctioning could therefore be a confounding factor and negatively skew our data on the effect of SVs. Authors’ contributions The duration of the study was only a total of one hour AS and JFF conceived the study, AS and CMA had full access to all of the with the SV in situ for 30 minutes. Clinically the same data in the study and take responsibility for the integrity of the data and patients would be using the SV for several hours at a the accuracy of the data analysis, including and especially any adverse effects. AS, LRC, KRD, CMA, PLC and JFF contributed substantially to the time. Due to the inability to compare the change in EELI study design, data analysis and interpretation, and the writing of the between sessions and the patients needing to remain in manuscript. All authors have read and approved the final version of this the same position, the EIT belt stayed in situ for the manuscript. Sutt et al. Critical Care (2016) 20:91 Page 8 of 9 Authors’ information 11. Gattinoni L, Caironi P, Cressoni M, Chiumello D, Ranieri VM, Quintel M, et al. AS is a senior Speech Pathologist in the ICU where the study took place. Lung recruitment in patients with the acute respiratory distress syndrome. Commencing employment in yet another ICU where tracheostomised N Engl J Med. 2006;354:1775–86. ventilated patients did not have a voice, the issue of no available scientific 12. Adler A, Amato MB, Arnold JH, Bayford R, Bodenstein M, Bohm SH, et al. evidence to support or negate the use of speaking valves was raised. JFF is Wither lung EIT: where are we, where do we want to go and what do we an intensivist in the same ICU, and also runs the Critical Care Research Group need to get there? Physiol Meas. 2012;33:679–94. that assisted in the trialing of the Electrical Impedance Tomography 13. Spooner A, Hammond N, Barnett A, Caruana L, Sharpe N, Fraser J. Head-of- prototype in the facility. AS and JFF decided to see what was actually bed elevation improves end-expiratory lung volumes in mechanically happening to lung recruitment when the cuff was deflated and speaking ventilated patients: a prospective observational study. Respir Care. valve put in-line with the patient’s ventilation circuit. Case studies 2014;59:1583–9. demonstrated supportive data, which then lead to designing of this study 14. Bikker I, van Bommel J, Miranda D, Bakker J, Gommers D. End-expiratory and AS commencing a PhD project. lung volume during mechanical ventilation: a comparison with referencevaluesand theeffectofpositiveend-expiratorypressure in intensive care unit patients with different lung conditions. Crit Care. Acknowledgements 2008;12:R145. AS acknowledges a peer-reviewed grant and PhD Scholarship from The 15. Hinz J, Hahn G, Neumann P, Sydow M, Mohrenweiser P, Hellige G, et al. Prince Charles Hospital Foundation (a not-for-profit charity that awards peer- End-expiratory lung impedance change enables bedside monitoring of reviewed grants); an NHMRC Scholarship; financial support from Passy-Muir end-expiratory lung volume change. Intensive Care Med. 2003;29:37–43. Inc to travel to the USA and present these research findings at the American 16. Grivans C, Lundin S, Stenqvist O, Lindgren S. Positive end-expiratory Thoracic Society 2015 meeting. None of the supporters had any involvement pressure-induced changes in end-expratory lung volume measured by in the study design, conduction, data analysis or preparation of the spirometry and electrical impedance tomography. Acta Anaesthesiol Scand. manuscript for publication. JFF acknowledges the support of the Queensland 2011;55:1068–77. Health Research Fellowship. 17. van Genderingen HR, van Vught AJ, Jansen JRC. Estimation of regional lung This research was approved by The Prince Charles Hospital Human Research volume changes by electrical impedance pressures tomography during a Ethics Committee and The University of Queensland Human Ethics and pressure-volume maneuver. Intensive Care Med. 2003;29:233–40. Research Committee. 18. Caruana L, Paratz J, Chang A, Fraser J. Narrative review: Electrical impedance tomography in the clinical assessment of lung volumes following Author details recruitment manoeuvres. Phys Ther Rev. 2011;16:66–74. Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia. 19. Costa ELV, Lima RG, Amato MBP. Electrical impedance tomography. Curr 2 3 School of Medicine, University of Queensland, Brisbane, Australia. Speech Opin Crit Care. 2009;15:18–24. Pathology Department, The Prince Charles Hospital, Brisbane, Australia. 20. Bikker IG, Leonhardt S, Bakker J, Gommers D. Lung volume calculated from Physiotherapy Department, The Prince Charles Hospital, Brisbane, Australia. electrical impedance tomography in ICU patients at different PEEP levels. Science & Engineering Faculty, Queensland University of Technology, Intensive Care Med. 2009;35:1362–7. Brisbane, Australia. Allied Health Collaborative, Metro North HHS, Brisbane, 21. Corley A, Caruana LR, Tronstad O, Adrian AG, Fraser JF. Oxygen delivery Australia. School of Applied Psychology, Menzies Health Institute through high-flow nasal cannulae increase end expiratory lung volume and Queensland, Griffith University, Brisbane, Australia. Critical Care Research reduce respiratory rate in post cardiac surgical patients when compared to Group, Sunshine Coast University Hospital, Brisbane, Australia. standard low flow oxygen. Br J Aneasth. 2011;107:998–1004. 22. Corley A, Spooner AJ, Barnett AG, Caruana LR, Hammond NE, Fraser JF. End- Received: 17 October 2015 Accepted: 19 February 2016 expiratory lung volume recovers more slowly after closed endotracheal suctioning than after open suctioning: A randomized crossover study. J Crit Care. 2012;27:742. e1-742.e7. 23. Bikker I, Leonhardt S, Reis Miranda D, Bakker J, Gommers D. Bedside References measurement of changes in lung impedance to monitor alveolar ventilation 1. Grossbach I, Stranberg S, Chlan L. Promoting effective communication for in dependent and non-dependent parts by electrical impedance patients receiving mechanical ventilation. Crit Care Nurse. 2011;31:46–61. tomography during a positive end-expiratory pressure trial in mechanically 2. Corley A, Sharpe N, Caruana L, Spooner A, Fraser J. Lung volume changes ventilated intensive care unit patients. Crit Care. 2010;14:R100. during cleaning of closed endotracheal suction catheters: A randomized 24. Caruana L, Paratz JD, Chang A, Barnett AG, Fraser JF. The time taken for the crossover study using electrical impedance tomography. Respir Care. regional distribution of ventilation to stabilise: an investigation using 2014;59:497–503. electrical impedance tomography. Anaesth Intensive Care. 2015;43:88–91. 3. Wolf GK, Arnold JH. Noninvasive assessment of lung volume: respiratory 25. Harrell M. Ventilator application of the Passy-Muir valve. 2015. www.passy- inductance plethysmography and electrical impedance tomography. Crit muir.com/ceu. Accessed 17 June 2015. Care Med. 2005;33:S163–9. 26. Winkworth AL, Davis PJ, Adams RD, Ellis E. Breathing patterns during 4. Tingay DG, Copnell B, Mills JF, Morley CJ, Dargaville PA. Effects of open spontaneous speech. J Speech Hearing Res. 1995;38:124–44. endotracheal suction on lung volume in infants receiving HFOV. Intensive 27. England SJ, Bartlett Jr D. Changes in respiratory movements of the human Care Med. 2007;33:689–93. vocal cords during hyperpnea. J Appl Physiol Respir Environ Exerc Physiol. 5. Fan E, Needham DM, Stewart TE. Ventilatory management of acute lung 1982;52:780–5. injury and acute respiratory distress syndrome. JAMA. 2005;294(22):2889–96. 28. Scholkmann F, Gerber U, Wolf M, Wolf U. End-tidal CO2: An important 6. Fukumoto M, Ota H, Arima H. Ventilator weaning using a fenestrated parameter for a correct interpretation in functional brain studies using tracheostomy tube with a speaking valve. Crit Care Resusc. 2006;8:117–9. speech tasks. Neuroimage. 2013;66:71–9. 7. Sutt A-L, Cornwell P, Mullany D, Kinneally T, Fraser J. The use of 29. Danan C, Dassieu G, Janaud JC, Brochard L. Efficacy of dead-space washout tracheostomy speaking valves in mechanically ventilated patients results in in mechanically ventilated premature newborns. Am J Respir Crit Care Med. improved communication and does not prolong ventilation time in 1996;153:1571–6. cardiothoracic intensive care unit patients. J Crit Care. 2015;30:491–4. 30. Dassieu G, Brochard L, Agudze E, Patkai J, Janaud JC, Danan C. Continuous 8. Sutt A-L, Fraser J. Speaking valves as standard care with tracheostomised tracheal gas insufflation enables a volume reduction strategy in hyaline mechanically ventilated patients in intensive care unit. J Crit Care. membrane disease: technical aspects and clinical results. Intensive Care 2015;30:1119–20. Med. 1998;24:1076–82. 9. Parmentier-Decrucq E, Poissy J, Favory R, Nseir S, Onimus T, Guerry M-J, et al. Adverse events during intrahospital transport of critically ill patients: 31. Casbolt S. Communicating with the ventilated patient–a literature review. incidence and risk factors. Ann Intensive Care. 2013;3:10. Nurs Crit Care. 2002;7:198–202. 10. Schwebel C, Clec’h C, Magne S, Minet C, Garrouste-Orgeas M, Bonadona A, 32. Karlsson V, Lindahl B, Bergbom I. Patients' statements and experiences et al. 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Speaking valves in tracheostomised ICU patients weaning off mechanical ventilation - do they facilitate lung recruitment?

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© Sutt et al. 2016
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1364-8535
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10.1186/s13054-016-1249-x
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Abstract

Background: Patients who require positive pressure ventilation through a tracheostomy are unable to phonate due to the inflated tracheostomy cuff. Whilst a speaking valve (SV) can be used on a tracheostomy tube, its use in ventilated ICU patients has been inhibited by concerns regarding potential deleterious effects to recovering lungs. The objective of this study was to assess endexpiratorylungimpedance (EELI) andstandard bedside respiratory parameters before, during and after SV use in tracheostomised patients weaning from mechanical ventilation. Methods: A prospective observational study was conducted in a cardio-thoracic adult ICU. 20 consecutive tracheostomised patients weaning from mechanical ventilation and using a SV were recruited. Electrical Impedance Tomography (EIT) was used to monitor patients’ EELI. Changes in lung impedance and standard bedside respiratory data were analysed pre, during and post SV use. Results: Use of in-line SVs resulted in significant increase of EELI. This effect grew and was maintained for at least 15 minutes after removal of the SV (p<0.001). EtCO showed a significant drop during SV use (p = 0.01) whilst SpO remained unchanged. Respiratory rate (RR (breaths per minute)) decreased whilst the SV was in situ (p <0.001), and heart rate (HR (beats per minute)) was unchanged. All results were similar regardless of the patients’ respiratory requirements at time of recruitment. Conclusions: In this cohort of critically ill ventilated patients, SVs did not cause derecruitment of the lungs when used in the ventilator weaning period. Deflating the tracheostomy cuff and restoring the airflow via the upper airway with a one-way valve may facilitate lung recruitment during and after SV use, as indicated by increased EELI. Trial registration: Anna-Liisa Sutt, Australian New Zealand Clinical Trials Registry (ANZCTR). ACTRN: ACTRN12615000589583. 4/6/2015. Keywords: Mechanical ventilation, Tracheostomy, Communication, FRC, Speaking valve, Lung recruitment * Correspondence: anna-liisa.sutt@health.qld.gov.au Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia School of Medicine, University of Queensland, Brisbane, Australia Full list of author information is available at the end of the article © 2016 Sutt et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Sutt et al. Critical Care (2016) 20:91 Page 2 of 9 Background measure EELV but current time-differencing systems rely Invasively ventilated patients are unable to phonate due on measuring the difference between end-inspiratory lung to either the endotracheal tube positioning through the impedance and EELI to measure tidal variation of imped- vocal folds, or when ventilating through the tracheos- ance and changes in EELI [12]. There is linear correlation tomy, the air bypassing the vocal folds. Speaking valves between changes in the EELI and changes in EELV [15–17], (SVs) can be used in-line with mechanical ventilation, although this relationship tends to overestimate changes but use of these requires deflation of the tracheostomy in EELV [16]. A limitation of time-differencing EIT is that cuff [1]. Cuff deflation causes a leak in the ventilator cir- it is unable to detect the pre-existing EELI [18, 19], which cuit, which has been considered detrimental to patients’ means it can only detect changes in EELI if the device re- ventilation, and potentially deleterious to weaning. mains in situ and running between readings [15, 18–20]. The key concern raised by physicians is that by deflat- Researchers, however, have successfully used EIT to de- ing the cuff, and thus, losing positive end-expiratory tect changes in EELI due to various clinical interven- pressure (PEEP) this could lead to loss of lung volume tions such as suctioning, position change, and changes through alveolar collapse. It has been demonstrated that in PEEP [13, 16, 20–23]. loss of PEEP in other events such as suctioning [2, 3] The aim of this study was to assess the effect of SVs and ventilator disconnection [4] causes loss of lung vol- on EELI. Based on the findings of prior case studies it ume. Current data indicate that “open lung ventilatory was hypothesised that there is an increase in global EELI strategies” minimise ventilator-induced lung injury [5]. with the SV in situ when patients are performing trials Hence, practices that may cause loss of lung volume off the ventilator (i.e., on 50 L of 40 % oxygen via the must be used with some degree of caution. tracheostomy). This may potentially be similar when pa- One small case series has described the apparently safe tients are constantly supported by mechanical ventila- use of SVs during weaning from mechanical ventilation tion, given restored physiological PEEP. Secondary aims [6]. Another study found no significant difference in included determining the effects of SV on the patient’s ventilator weaning and decannulation times post the respiratory rate (RR), heart rate (HR), oxygen saturation introduction of in-line SVs into an adult intensive care (SpO ) and end-tidal carbon dioxide (EtCO ). The po- 2 2 unit (ICU) [7, 8]. Whilst these studies provide prelimin- tential effect on respiratory mechanics of talking versus ary clinical support for use of in-line SVs with tracheos- quietly breathing with the SV in situ, and the effects of tomised mechanically ventilated patients, there are no the SV and its dependence on the patients’ ventilatory physiological data to prove or allay fears. requirements at the time, were also investigated. Currently there are no data on the effect of SVs on end-expiratory lung volume (EELV), a critical point Methods when the lungs are at most risk of collapsing. An SV is a Following human ethics approval by the Institutional one-way valve that allows for inspiration via the trache- Review Board (HREC/13/QPCH/95) a prospective obser- ostomy tube whilst expiration is redirected to the upper vational study (ACTRN12615000589583) using a repeated airway via the vocal folds, enabling phonation [1] and re- measures design was conducted. The study took place in a stored upper airway resistance. Hence, it can be consid- primarily cardiothoracic ICU at a metropolitan tertiary ered functionally as a PEEP valve on the tracheostomy. teaching hospital. Consecutive patients who were tra- As there is no airflow back into the ventilator tubing cheostomised and being weaned from mechanical ventila- with the one-way valve, current in situ monitoring of tion, from November 2013 to December 2014, were ventilation with standard bedside equipment provides considered for inclusion in the study if they were tolerat- the clinician with limited information on ventilation. ing a SV for a minimum of 30 minutes, as jointly assessed While computerised tomography or magnetic resonance by a speech pathologist and a physician. Patients were ex- imaging may be able to provide this information, the re- cluded if they had significant language or cognitive defi- peated use these imaging procedures could be seen as cits, or were not suitable to wear an EIT belt (i.e., patients ethically unjustifiable, expensive, possibly requiring a with ventricular assist devices, open chest, extensive level of sedation, and putting patients at risk with the sternal dressings/drains or those dependant on cardiac transfer outside of the ICU environment [9, 10]. pacing). In total 20 patients were recruited into two Electrical impedance tomography (EIT) is a radiation- groups: 1) 10 patients on pressure support ventilation free real-time bedside imaging tool capable of measuring (PSV) and 2) 10 patients having trial periods off mechan- the air movement in and out of the thorax [11–14]. It ical ventilation (and transferred onto high-flow or low- has been observed as being a safe, reliable and reprodu- flow oxygen via the tracheostomy). All patients provided cible technique to assess regional ventilation in the lung, written informed consent, or for those unable to sign for specifically during recruitment manoeuvres [3]. In the written consent, the consent was provided by a legally future it may be possible for absolute EIT to directly authorised person (e.g., family member) or by the patient’s Sutt et al. Critical Care (2016) 20:91 Page 3 of 9 nurse witnessing verbal consent. The study was conducted adapter that accommodated the EtCO /P catheter. Ven- 2 aw in accordance with the ethical standards laid down in the tilator settings were changed while the SV was in situ in 1964 Declaration of Helsinki. the patients supported by pressure support ventilation (PSV). This included switching the system to non-invasive Measures (NIV) mode for PSV (to more easily control expiratory Following informed consent, patients were enrolled in alarms) and reducing the set ventilator-delivered PEEP by the study. EIT (Pulmovista, Draeger Medical, Lubeck, 5cmH O [25]. This change in settings was based, in the Germany) measurements were taken continuously for absence of any scientific data to define optimal settings, 60 minutes with the frame rate set to 10 Hz to give the on recommendations by the SV manufacturer. During the EELI per breath. Transitions to and from SV were followed second data collection period patients were instructed to by 15-minute periods, to allow for stabilisation [24]. continue to breathe normally and avoid talking. Once the Set ventilator-delivered PEEP and fraction of inspired third data collection period commenced the patients were oxygen (FiO ) data were collected from the ventilator instructed to converse as they wished with the researcher, (Puritan Bennett 840, Covidien, Dublin, Ireland). HR family member, or healthcare team. When verbal commu- and SpO were measured with pulse oximeter (504, Cri- nication was limited, the researcher used picture cards ticare systems, Waukesha, WI, USA). Airway pressure and open-ended questions to facilitate verbal output. As (P ) was measured directly via a neonatal feeding cath- there is a suggested difference in breathing patterns be- aw eter (6 F) introduced through the Luer port of an tween different speech tasks (planned vs non-planned) adaptor (Ikaria, Hampton, NJ, USA) advanced to lie just [26], no set tasks were given to participants, and spontan- distal to the tracheostomy cannula in the trachea, and eous speech was encouraged. At the completion of period measured with a pressure transducer (PPT, Honeywell, 3, the ventilator settings were returned to baseline, the SV Morris Plains, NJ, USA). Oximeter and pressure data was removed, and the tracheostomy cuff re-inflated. Data were collected at 200 Hz (PowerLab, AD Instruments, collection continued in the fourth period as per baseline Sydney, NSW, Australia). EtCO was sampled from the conditions. Routine tracheal suctioning was performed feeding tube and measured (Marquette Solar 8000, GE during data collection as per individual patient needs. Healthcare, Little Chalfont, UK). EtCO was measured continuously throughout the 60 minutes apart from 2 Data analysis minutes before, during and after SV use when continu- Data were analysed offline post data collection using ous P measurements were taken through the same commercially available Draeger software (Draeger EIT aw catheter. There was no flow through the catheter during Data Analysis Tool 6.1). EELI was averaged across the pressure measurements, to ensure highest possible fidel- readings and displayed as mean EELI for each of the ity. All data were collected on a breath-to-breath basis four data collection periods. A mixed effects regression using custom-written software. model was used to investigate the changes in EELI com- pared to baseline. Planned comparisons between base- Procedure line and each subsequent data collection period were The patients were positioned either in bed at 45 degrees conducted using the paired t test, for RR, EtCO ,HR or in a straight-backed chair with the EIT electrode belt and SpO . The level of significance was set at p <0.05 around their chest at the level of the fifth to sixth anter- throughout, with 95 % confidence intervals quoted where ior intercostal space. As patient position has been shown appropriate. All statistical analyses were conducted using to have an impact on ventilation distribution [13], we STATA (version 12.0). TM ensured that there were no significant changes in patient positioning throughout the data collection. A neonatal Results feeding catheter was inserted as described above and the During the study period 55 tracheostomised patients pulse oximeter was positioned on the finger. used an SV, and all were assessed for inclusion in the Fifteen minutes of data were recorded continuously study. Of these patients 20 met the inclusion criteria and during four discrete periods: (1) baseline – prior to were enrolled in the study. Figure 1 details the reasons placement of the SV in-line with mechanical ventilation; for exclusion or non-participation in the study. (2) quiet breathing with SV in-line; (3) talking with SV The mean age of the patients in the study was 60.4 ± in-line; and (4) post removal of the in-line SV. After the 14.9 years (50 % male). The mean age for all tracheosto- baseline period the tracheostomy cuff was deflated with mised patients in the ICU throughout the recruitment simultaneous tracheal suctioning to clear secretions period was 57.1 ± 17.4 years (64.6 % male). On average, pooling above the cuff and minimise aspiration. The SV patients used an SV for 2.5 days prior to recruitment to (PMV007, Passy Muir Inc., Irvine, CA, USA) was then the study. There were 10 patients assessed whilst being inserted in-line with the ventilation circuit following the ventilated with PSV, and 10 assessed during periods off Sutt et al. Critical Care (2016) 20:91 Page 4 of 9 Fig. 1 Participant selection chart. SV speaking valve, BiVAD biventricular assist device, EIT electrical impedance tomography, LVAD left ventricular assist device, PMSV Passy-Muir speaking valve, PPM permanent pace maker the ventilator (9 on high-flow, one on low-flow oxygen) were seen in data collection period 3 and 4, respectively for the duration of data collection. All but one of the pa- (see Fig. 2 and Table 3). tients who were assessed off ventilator were still requir- Of note, patients’ ventilatory requirements at the time ing >12 h/day of mechanical ventilation. See Table 1 for of recruitment did not have a significant impact on the specifics of respiratory requirements. The majority change in EELI, any of the respiratory parameters or of patients (17) had their tracheostomy tubes inserted HR. The patients who were supported on PSV during percutaneously in the ICU. Primary reasons for ICU ad- data collection had an initial non-significant drop in mission included cardiac surgery (n = 13, 65 %) or re- EELI. However, a similar increase in EELI with patients spiratory disease (n = 5). Nineteen of the patients (95 %) off the ventilator was noted for the third and fourth had received a tracheostomy due to prolonged need for period of data collection (see Fig. 2). mechanical ventilation. Patient number 3 had the trache- EtCO decreased significantly during SV use (p = 0.02 ostomy initially inserted for surgery in the upper airway, for period 2 and p = 0.01 for period 3) and returned to but required prolonged respiratory support following baseline for period 4. RR decreased significantly from cardiac surgery. See Table 2 for a more detailed descrip- baseline while SV was used in-line with the ventilation tion of all patients in the study. circuit (p =0.001, p <0.001 for periods 2 and 3, respect- A statistically significant increase in EELI was ob- ively), and returned to baseline once the SV was removed. served between baseline and all subsequent data collec- HR and SpO did not change significantly throughout tion periods. A mean increase by 19.7 % (213 units) data collection. occurred from baseline to period 2 (SV + quiet breath- Only limited data on P were captured (three partici- aw ing, p = 0.034). Further increase from baseline by 83.6 % pants with full data, seven with partial data). These data (905 units) (p <0.001) and 120 % (1,299 units) (p <0.001) all indicated similar drops in P coinciding with the aw Sutt et al. Critical Care (2016) 20:91 Page 5 of 9 Table 1 Participant ventilation needs actions of the SV) and its deflated cuff, ensuring more residual air in the lungs at the end of expiration. Further Patient number Vent. needs Weaned Y/N PS PEEP FiO Flow analysis is required to confirm that lung hyperinflation 1 HFTP N N/A N/A 40 % 40 L did not occur as it could be argued that an increase in 2 HFTP Y N/A N/A 40 % 40 L EELI may correlate to tidal hyperinflation. We used 3 LFTP N N/A N/A 30 % 5 L SpO2 and EtCO as simple measures to exclude patho- 4 HFTP N N/A N/A 40 % 50 L logical degrees of hyperinflation, but this cannot exclude 5 PSV N 10 5 40 % N/A it fully. Of note, all patients had been using an SV before 6 HFTP N N/A N/A 40 % 50 L the study with no gross signs of hyperinflation on rou- tine chest radiographs. 7 HFTP N N/A N/A 40 % 40 L The subsequent increase in EELI when patients talked 8 PSV N 15 10 35 % N/A is explicable through the additional, but variable, upper 9 HFTP N N/A N/A 50 % 50 L airway resistance caused by the glottis [27] with vocal 10 PSV N 13 10 40 % N/A folds closing and opening during attempts at phonation. 11 HFTP N N/A N/A 40 % 40 L The SV appeared to act as a recruitment manoeuvre. An 12 PSV N 10 7.5 40 % N/A increase in EELI was observed during SV use and its ef- fect remained after removal of the SV from the patient’s 13 PSV N 15 5 35 % N/A ventilation circuit. EELI remained stable for 8–9 minutes 14 HFTP N N/A N/A 30 % 30 L once the SV was removed from the ventilator circuit 15 HFTP N N/A N/A 40 % 40 L and the tracheostomy cuff re-inflated before a further in- 16 PSV N 10 8 40 % N/A crease occurred. 17 PSV N 10 5 35 % N/A There are several potential explanations for the drop 18 PSV N 12 5 40 % N/A in EtCO during the SV use. One reason may be a drop in EtCO due to using one’s voice, as observed in a study 19 PSV N 12 8 45 % N/A 2 of healthy subjects [28]. Another potential reason is 20 PSV N 12 7.5 40 % N/A dead-space washout in the upper airway that has been respiratory needs at point of recruitment. Considered not weaned if needed found in other studies [29, 30] to coincide with an in- mechanical ventilation (Vent.) in the preceding 24 h FiO fraction of inspired oxygen, Flow O flow requirements at point of 2 2 crease in tidal volumes. With our current data, we can- recruitment, HFTP high-flow tracheostomy piece (>30 L/min of O ), LFTP not categorically state, however, that tidal volumes low-flow tracheostomy piece (<30 L/min of O ), PEEP positive end-expiratory pressure, PS pressure support, PSV pressure support ventilation increased for patients in this study. A third potential aetiological cause may be that the exhaled air just past the reduction of ventilator-delivered PEEP for the duration tracheostomy cannula from where EtCO was measured of the SV use. Ventilator data showed that there was was being diluted with fresh inspiratory flow in all patients minimal expired tidal volume when the SV was in-line on high-flow oxygen, and some on PSV while the cuff was (see Table 4). deflated. Transcutaneous carbon dioxide (TcCO )and arterial pressure of carbon dioxide (PaCO ) may need to Discussion be measured in similar studies in the future. The findings indicated that use of SVs in this cohort did Only limited data on P were captured, due to rapid aw not result in any significant de-recruitment of the lungs, and repeated obstruction of the fine-bore catheter with which was contrary to concerns initially voiced by physi- secretions due to presence of no flow through the cath- cians. Standard bedside respiratory data demonstrated eter during the numerous 2-minute measurements. A reduced work of breathing with adequate gas exchange. similar reduction in P coinciding with the turning aw The increase in EELI may indicate increased EELV. Fur- down of the set ventilator-delivered PEEP for the dur- ther analysis is necessary to more fully determine venti- ation of the SV use was noted. However, due to lack of lation distribution, as an increase in EELV could be due data, it is difficult to draw any conclusions. Further stud- to further recruitment or over-inflation of already aer- ies are needed to further look at P and ventilator- aw ated parts of the lung. delivered PEEP with and without an SV in circuit. The increase in EELI with the SV in the ventilator cir- It was surprising to observe that the ventilator demon- cuit is likely to occur through the restoration of the pa- strated substantial exhaled tidal volume whilst the SV tient’s ability to breathe through the larynx and upper was in situ. This may indicate the presence of a leak in airway, as opposed to the continuously patent tracheos- the SV or some form of back-pressure. This means that tomy tube. Upper airway resistance is increased due to the ventilator may actually still be delivering PEEP when the resistance created by exhalation against and around a one-way valve is in place, and will be the subject of the effectively closed tracheostomy tube (through the further studies. Sutt et al. Critical Care (2016) 20:91 Page 6 of 9 Table 2 Demographics and tracheostomy data Patient Age, Gender Primary reason for admission to ICU Days TT Days to Insertion TT type and size Days of SV use number years to SV, n decannulation, n method when recruited, n 1 63 M acute myocardial infarct; CABG 11 18 perc long flange Portex 8 2 2 48 F acute myocardial infarct; tamponade 5 12 perc cuffed Portex 8 6 3 72 F Buccal SCC + CABG 5 7 surg cuffed Portex 7 0 4 71 M tissue AVR for infective endocarditis 2 4 perc cuffed Portex 8 1 5 29 M endarterectomy 2 5 perc cuffed Portex 8 1 6 77 M CABG x3 and mechanical AVR 6 23 perc cuffed Portex 8 1 7 44 F aortic dissection 6 7 perc cuffed Portex 8 1 8 33 F endarterectomy 4 12 perc cuffed Portex 7 4 9 61 M H1N1, ARDS 12 23 perc cuffed Portex 8 8 10 70 M CABGx2 3 5 perc cuffed Portex 8 1 11 70 F cardiac tamponade 4 6 perc cuffed Portex 7 1 12 43 F PE 2 5 perc cuffed Portex 7 2 13 47 F Influenza A ARDS 4 6 perc cuffed Portex 8 1 14 70 F CAP 2 7 perc cuffed Portex 8 5 15 58 M CAP 3 N/A surg cuffed Portex 8 1 16 62 F CAP 2 6 perc cuffed Portex 8 1 17 74 F extensive GI surgery 10 31 perc cuffed Portex 7 7 18 78 M CABG x4 3 5 perc cuffed Portex 8 2 19 60 M chest trauma 7 12 surg long flange Portex 8 2 20 77 M repeat sternotomy for tissue AVR, CABGx1 4 13 perc cuffed Portex 8 2 M male, F female,SV speaking valve, ARDS acute respiratory distress syndrome, AVR aortic valve repair, CABG coronary artery bypass graft, CAP community acquired pneumonia, GI gastrointestinal, PE pulmonary embolism, perc percutaneous, SCC smallcellcarcinoma, surg surgical, TT tracheostomy tube Communication is a key issue for ventilated patients, participate in care [31, 34–36], poor sleep, and increased who find the inability to speak distressing [31–33]. Diffi- anxiety and stress levels [37], which has both short-term culties with communication in the tracheostomised and long-term impacts on patient outcomes in ICU and patient population have been associated with social with- post ICU stay. By demonstrating the potential physio- drawal, leading to depression, lack of motivation to logical benefits on top of the already known and more obvious psychological benefits, SVs present an excellent way to improve patient care in the ICU. Increased use of SV brings with it multiple questions, such as, for how long should the SVs be used at any one time? Does this lead to fatigue? Should the SVs be used with patients during mobilisation? Future studies are needed to look at the efficacy of SVs in the weaning and Table 3 Outcome measures across four time periods Baseline (1) SV (2) SV-talk (3) Post SV (4) SpO 96.5 (0.5) 95.5 (0.7) 94.7 (0.7) 96.0 (0.8) RR 25 (1.6) 22 (1.5)* 20 (1.7)* 25 (1.4) HR 95 (2.8) 95 (2.4) 96 (2.9) 96 (3.0) Fig. 2 Mean end-expiratory lung impedance (EELI) vs time with EtCO 29 (1.1) 27 (1.1)* 26 (1.2)* 28 (1.0) average EELI trend for non-vent and pressure support ventilation EELI, mean 1082 (57) 1295 (61)* 1987 (60)* 2381 (75)* (PSV). Mean EELI is plotted on the y-axis against a nominal time base. A lowess smoothing line has been added to clarify the overall trend. All data are presented as mean (standard error of the mean) *Statistically significant change, p <0.05 non-vent patient off mechanical ventilation during recruitment, SV EtCO end-tidal carbon dioxide, HR heart rate, EELI end-expiratory lung impedance, speaking valve RR respiratory rate, SpO peripheral capillary oxygen saturation, SV speaking valve 2 Sutt et al. Critical Care (2016) 20:91 Page 7 of 9 Table 4 Airway pressure (P ), expired tidal volume (TV) and duration of the study with the patients sitting up. There- aw peak inspiratory pressure (PIP) fore it was not feasible to monitor the patients for Baseline (1) SV (2) Post SV (4) longer. P ,(n =7) 10.5 cmH O 5.6 cmH O 10.7 cmH O aw 2 2 2 b c TV, L (n = 10) 0.550 0.024 0.534 Conclusions PIP (n = 10) 19.8 15.1 20 When SVs were used in this cohort of cardio-respiratory Full data for all three periods from three patients only patients, we observed no evidence of lung de-recruitment Data from all 10 mechanically ventilated patients in the study whilst weaning from mechanical ventilation. Deflation of Two patients had higher TV of 0.106 L and 0.088 L on average, and two the tracheostomy cuff with restoration of the airflow via patients had TV of 0.0 L. SV speaking valve, P airway pressure, TV tidal volume aw the upper airway with a one-way valve facilitated an in- crease in EELI both during and after a period of SV use in rehabilitation process of mechanically ventilated tra- our cohort of patients, which may indicate recruitment of cheostomised ICU patients. the lungs. Use of the SV resulted in reduced RR and a re- duced end-tidal CO . Limitations of the study This study was conducted on a specific cohort of ICU patients, mostly cardiothoracic, and extrapolation of Key messages these data to patients with different pathological condi- tions may not be wise. This is even more relevant in pa-  Speaking valve use facilitated an increase in end- tients with spinal and brain injuries in whom central expiratory lung impedance in tracheostomised control of breathing might be affected. cardiothoracic ICU patients weaning off mechanical No patients in this study were ventilated using ventilation volume-controlled modes, hence there is a need to de-  Increased end-expiratory lung impedance was termine whether restored physiological PEEP through maintained and further increased for at least the SV helps compensate for the leak in the ventilatory 15 minutes post removal of the speaking valve from circuit similarly in volume-controlled ventilation. the ventilation circuit Airway pressures were only measured for the second  Speaking valve use resulted in a reduced respiratory half of the study with limited data obtained as described rate and reduced end-tidal CO when used in above. Hence the reported P data may be a poor rep- tracheostomised cardiothoracic ICU patients aw resentation of the actual P across the time points in weaning off mechanical ventilation aw the study, and was therefore not reported in detail. Dif- ferent methods to obtain these important data are rec- Abbreviations EELI: end-expiratory lung impedance; EELV: end-expiratory lung volume; ommended for future similar studies. Minor difficulties EIT: electrical impedance tomography; EtCO : end-tidal carbon dioxide; also occurred with EtCO measurements (measured in FiO : fraction of inspired oxygen; HFTP: high-flow tracheostomy piece (as all patients in the study) through the same catheter. defined by >30 L of continuous O via tracheostomy tube); HR: heart rate; ICU: intensive care unit; LFTP: low-flow tracheostomy piece as defined by However, due to the presence of airflow in the catheter <30 L of continuous O via tracheostomy tube); P : airway pressure; 2 aw during EtCO measurement, this reduced the likelihood PEEP: positive end-expiratory pressure; PIP: peak inspiratory pressure; of the catheter becoming blocked with secretions, and PSV: pressure support ventilation; RR: respiratory rate; SpO : peripheral capillary oxygen saturation; SV: speaking valve; TV: tidal volume. resulted in almost full data collection across 60 minutes obtained from all patients. Competing interests Routine suctioning was performed as per patient needs AS received financial support (New Investigator Grant and PhD Scholarship) throughout data collection. It is known that tracheal from The Prince Charles Hospital Foundation to conduct the study, and suctioning causes a degree of de-recruitment [22]. The financial support from Passy-Muir Inc. to present preliminary findings of the study at the American Thoracic Society 2015 meeting in Denver. AS is quantitative effect of suctioning was not specifically ana- currently being supported by NHMRC Scholarship. None of the supporters lysed as part of this study, nor were these periods ex- had any involvement in the study design or conduction of it. JFF has cised from data analysis. De-recruitment caused by received grant support from Draeger in previous studies using EIT. For the remaining authors, none were declared. tracheal suctioning could therefore be a confounding factor and negatively skew our data on the effect of SVs. Authors’ contributions The duration of the study was only a total of one hour AS and JFF conceived the study, AS and CMA had full access to all of the with the SV in situ for 30 minutes. Clinically the same data in the study and take responsibility for the integrity of the data and patients would be using the SV for several hours at a the accuracy of the data analysis, including and especially any adverse effects. AS, LRC, KRD, CMA, PLC and JFF contributed substantially to the time. Due to the inability to compare the change in EELI study design, data analysis and interpretation, and the writing of the between sessions and the patients needing to remain in manuscript. All authors have read and approved the final version of this the same position, the EIT belt stayed in situ for the manuscript. Sutt et al. Critical Care (2016) 20:91 Page 8 of 9 Authors’ information 11. Gattinoni L, Caironi P, Cressoni M, Chiumello D, Ranieri VM, Quintel M, et al. AS is a senior Speech Pathologist in the ICU where the study took place. Lung recruitment in patients with the acute respiratory distress syndrome. Commencing employment in yet another ICU where tracheostomised N Engl J Med. 2006;354:1775–86. ventilated patients did not have a voice, the issue of no available scientific 12. Adler A, Amato MB, Arnold JH, Bayford R, Bodenstein M, Bohm SH, et al. evidence to support or negate the use of speaking valves was raised. JFF is Wither lung EIT: where are we, where do we want to go and what do we an intensivist in the same ICU, and also runs the Critical Care Research Group need to get there? Physiol Meas. 2012;33:679–94. that assisted in the trialing of the Electrical Impedance Tomography 13. Spooner A, Hammond N, Barnett A, Caruana L, Sharpe N, Fraser J. Head-of- prototype in the facility. AS and JFF decided to see what was actually bed elevation improves end-expiratory lung volumes in mechanically happening to lung recruitment when the cuff was deflated and speaking ventilated patients: a prospective observational study. Respir Care. valve put in-line with the patient’s ventilation circuit. Case studies 2014;59:1583–9. demonstrated supportive data, which then lead to designing of this study 14. Bikker I, van Bommel J, Miranda D, Bakker J, Gommers D. End-expiratory and AS commencing a PhD project. lung volume during mechanical ventilation: a comparison with referencevaluesand theeffectofpositiveend-expiratorypressure in intensive care unit patients with different lung conditions. Crit Care. Acknowledgements 2008;12:R145. AS acknowledges a peer-reviewed grant and PhD Scholarship from The 15. Hinz J, Hahn G, Neumann P, Sydow M, Mohrenweiser P, Hellige G, et al. Prince Charles Hospital Foundation (a not-for-profit charity that awards peer- End-expiratory lung impedance change enables bedside monitoring of reviewed grants); an NHMRC Scholarship; financial support from Passy-Muir end-expiratory lung volume change. Intensive Care Med. 2003;29:37–43. Inc to travel to the USA and present these research findings at the American 16. Grivans C, Lundin S, Stenqvist O, Lindgren S. Positive end-expiratory Thoracic Society 2015 meeting. None of the supporters had any involvement pressure-induced changes in end-expratory lung volume measured by in the study design, conduction, data analysis or preparation of the spirometry and electrical impedance tomography. Acta Anaesthesiol Scand. manuscript for publication. JFF acknowledges the support of the Queensland 2011;55:1068–77. Health Research Fellowship. 17. van Genderingen HR, van Vught AJ, Jansen JRC. Estimation of regional lung This research was approved by The Prince Charles Hospital Human Research volume changes by electrical impedance pressures tomography during a Ethics Committee and The University of Queensland Human Ethics and pressure-volume maneuver. Intensive Care Med. 2003;29:233–40. Research Committee. 18. Caruana L, Paratz J, Chang A, Fraser J. Narrative review: Electrical impedance tomography in the clinical assessment of lung volumes following Author details recruitment manoeuvres. Phys Ther Rev. 2011;16:66–74. Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia. 19. Costa ELV, Lima RG, Amato MBP. Electrical impedance tomography. Curr 2 3 School of Medicine, University of Queensland, Brisbane, Australia. Speech Opin Crit Care. 2009;15:18–24. Pathology Department, The Prince Charles Hospital, Brisbane, Australia. 20. Bikker IG, Leonhardt S, Bakker J, Gommers D. 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