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Cenk Kirakli, MD; Ilknur Naz, PT, PhD; Ozlem Ediboglu, MD
Author and Funding Information

FINANCIAL/NONFINANCIAL DISCLOSURES: None declared.

CORRESPONDENCE TO: Cenk Kirakli, MD, Pulmonary and Critical Care Medicine, Intensive Care Unit, Dr. Suat Seren Chest Diseases and Thoracic Surgery Training and Research Hospital, Yenisehir-Izmir, Turkey


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;149(1):281-282. doi:10.1016/j.chest.2015.09.013
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First, we would like to thank to Dr Grieco and colleagues for their interest in our study comparing adaptive support ventilation and pressure assist/control ventilation in medical patients in the ICU. We are grateful for the insightful comments to our article and are happy to respond to their comments as follows.

In the current study, pressure assist/control ventilation (P-ACV) mode was used in the control group because adaptive support ventilation (ASV) also works as a pressure-controlled mode in passive patients. When patients met readiness to wean criteria, they were tested immediately with a spontaneous breathing trial (SBT) with a T-tube for extubation. Patients who fail the initial SBT should receive a nonfatiguing mode of mechanical ventilation (generally either assist-control or PSV) as suggested in the Weaning Task Force of the European Respiratory Society. We selected P-ACV as the ventilation mode in patients failing the first SBT. The only difference regarding synchronization between P-ACV and PSV in spontaneously breathing patients is the cycling parameter (time in P-ACV and flow in PSV). Theoretically, PSV could be selected as the ventilation mode in these patients, but we believe that if the cycling parameter is set with caution and adjusted according to patients’ needs in P-ACV, synchrony would not be inferior compared with PSV. There are also data regarding better patient ventilator interaction or hemodynamic effects with time cycling compared with flow cycling in patients undergoing noninvasive ventilation., Although the clinicians in charge were cautious when adjusting the cycling parameter (inspiratory time) in P-ACV according to patient ventilator synchrony, the automatic switch to PSV provided by ASV with no intervention from the clinician as soon as the patient triggered the breath may have had an impact on the outcome. Even if patients in the P-ACV mode were switched to PSV, this intervention could be have been delayed owing to late recognition of the actively breathing patient, especially during night shifts in centers with a low ratio of nurses to patients, as in ours. We think that this is one advantage of automatic closed-loop modes in these kinds of ICUs with a high workload. There are also data showing that extubation readiness cannot be recognized in a timely manner in at least 15% of patients recovering from respiratory failure, even in the presence of a ventilation protocol. In our study, we could not evaluate physiologic data that could affect patient ventilator interaction because of technical limitations, so this issue deserves further research to be clarified.

Regarding the sedation used for both groups, our policy is to use little or no sedation, especially in actively breathing patients. Instead, physicians in charge try to set the triggering and cycling parameters according to individual patients’ needs. Besides, a similar strict weaning protocol was used in the control group as in the ASV group.

Fluid overload is one of the most common causes of SBT failure. We used standard protocols to assess fluid responsiveness and same fluid and nutrition therapies for both groups, as described in the Methods section of the study. As this was a randomized controlled trial, patients who could be affected by fluid overload, such as those with cardiac failure and sepsis, were equally distributed in both groups, so we might expect that this issue could not have an impact on the overall outcome.

This study reflects the outcomes of a single center experienced in ASV, so the results should be interpreted with caution, as suggested. Although automatic closed-loop modes might help ICU physicians to wean and extubate patients earlier, the clinical judgment of an experienced intensivist is still important, and we believe that the use of these new technologies needs further evaluation with multicenter studies to increase the external validity of the results.

References

Kirakli C. .Naz I. .Ediboglu O. .Tatar D. .Budak A. .Tellioglu E. . A randomized controlled trial comparing the ventilation duration between adaptive support ventilation and pressure assist/control ventilation in medical patients in the ICU. Chest. 2015;147:1503-1509 [PubMed]journal. [CrossRef] [PubMed]
 
Boles J.M. .Bion J. .Connors A. .et al Weaning from mechanical ventilation. Eur Respir J. 2007;29:1033-1056 [PubMed]journal. [CrossRef] [PubMed]
 
Calderini E. .Confalonieri M. .Puccio P.G. .Francavilla N. .Stella L. .Gregoretti C. . Patient-ventilator asynchrony during noninvasive ventilation: the role of expiratory trigger. Intensive Care Med. 1999;25:662-667 [PubMed]journal. [CrossRef] [PubMed]
 
Kirakli C. .Cerci T. .Ucar Z.Z. .et al Noninvasive assisted pressure-controlled ventilation: as effective as pressure support ventilation in chronic obstructive pulmonary disease? Respiration. 2008;75:402-410 [PubMed]journal. [CrossRef] [PubMed]
 
Chen C.W. .Wu C.P. .Dai Y.L. .et al Effects of implementing adaptive support ventilation in a medical intensive care unit. Respir Care. 2011;56:976-983 [PubMed]journal. [CrossRef] [PubMed]
 

Figures

Tables

References

Kirakli C. .Naz I. .Ediboglu O. .Tatar D. .Budak A. .Tellioglu E. . A randomized controlled trial comparing the ventilation duration between adaptive support ventilation and pressure assist/control ventilation in medical patients in the ICU. Chest. 2015;147:1503-1509 [PubMed]journal. [CrossRef] [PubMed]
 
Boles J.M. .Bion J. .Connors A. .et al Weaning from mechanical ventilation. Eur Respir J. 2007;29:1033-1056 [PubMed]journal. [CrossRef] [PubMed]
 
Calderini E. .Confalonieri M. .Puccio P.G. .Francavilla N. .Stella L. .Gregoretti C. . Patient-ventilator asynchrony during noninvasive ventilation: the role of expiratory trigger. Intensive Care Med. 1999;25:662-667 [PubMed]journal. [CrossRef] [PubMed]
 
Kirakli C. .Cerci T. .Ucar Z.Z. .et al Noninvasive assisted pressure-controlled ventilation: as effective as pressure support ventilation in chronic obstructive pulmonary disease? Respiration. 2008;75:402-410 [PubMed]journal. [CrossRef] [PubMed]
 
Chen C.W. .Wu C.P. .Dai Y.L. .et al Effects of implementing adaptive support ventilation in a medical intensive care unit. Respir Care. 2011;56:976-983 [PubMed]journal. [CrossRef] [PubMed]
 
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