Cenk Kirakli, MD ; Ilknur Naz, PT, MS ; Ozlem Ediboglu, MD ; Dursun Tatar, MD ; Ahmet Budak, MD ; and Emel Tellioglu, MD A Randomized Controlled Trial Comparing the Ventilation Duration Between Adaptive Support Ventilation and Pressure Assist/Control Ventilation in Medical Patients in the ICU 호흡기내과 R3. 박민아 CHEST2015; 147(6):

Introduction Closed-loop modes such as adaptive support ventilation (ASV) may i mprove the adaptation of the ventilator to the patient’s ventilatory n eeds and facilitate early recognition of the ability to breathe spontan eously Adaptive support ventilation (ASV) : uses an algorithm to select the optimal respiratory rate (RR)/tidal volume (Vt ) combination associated with the least work of breathing : adaptive pressure controlled ventilation in passive patients and switches to an adaptive pressure support ventilation (PSV) in spontaneously breathing patients

Introduction Some studies have reported shorter weaning times, fewer alarms, and fewer manipulations with ASV as compared with conventional modes, especially in the weaning period Purpose  Test the hypothesis that ASV may shorten the total mechanical ventilation (MV) duration when compared with conventional ventilation  Evaluate the impact of ASV on weaning duration, total number of manual settings of the ventilator, and weaning success rates

Materials and Methods  Patients - admitted to the ICU between December 2011 and December intubated, and mechanically ventilated for > 24 h were included in the study - Exclusion criteria ventilated for < 24 h intubated and mechanically ventilated for > 24 h in another center prior to ICU admission with a tracheotomy treated with home MV ARDS  randomized into ASV or pressure assist/control ventilation (P-ACV)

Materials and Methods  Study design and Protocols  ASV group - minute volume (MinVol) was expressed as a percentage (MinVol %) - setting was started at 100% and was adjusted according to the PaCO 2 levels for passive patients or patient’s RR for spontaneously breathing patients - PEEP (positive end-expiratory pressure) : cm H 2 O - FiO 2 : gradually decreased from 100% to 40% according to the arterial oxygen saturation - Inspiratory trigger sensitivity : 2 L/min - Expiratory trigger sensitivity : 40% of the maximal inspiratory flow

Materials and Methods  Study design and Protocols  P-ACV group - used as a conventional mode - Pressure control level : started at 30 cm H 2 O titrated to obtain a V T of mL/kg - PEEP, FiO 2, Inspiratory trigger sensitivity : equal to ASV group - RR : breaths/min - Inspiratory time : 1.5 s - Inspiratory to expiratory ratio (I/E ratio) : adjusted by either changing the inspiratory time or RR or both

Materials and Methods  Study design and Protocols  Weaning Period - European Respiratory Society Weaning Task Force recommendations - Readiness to wean : assessed every morning by the respiratory therapist and physician : criteria >> adequate cough absence of excessive tracheobronchial secretions stable cardiovascular status with sBP mmHg with no or minimal vasopressor stable metabolic status PaO 2 /FiO 2 ≥ 150 with FiO 2 ≤ 40% with RR ≤ 35 breaths/min  spontaneous breathing trial (SBT) with a T-tube for 2hr T-tube trial was performed for 3 consecutive days (one trial for each day)

Materials and Methods  Study design and Protocols  Measurements, Definitions, and Outcomes - Weaning success : independence from MV (invasive or noninvasive) at least 48 h after extubation - Weaning duration : time beginning from the first SBT until the last successful extubation - Total MV duration : time from intubation until the last successful extubation

Results

Total MV duration : ASV < P-ACV Weaning duration : ASV < P-ACV

Results

Discussion The main finding of this study - ASV was able to reduce total MV and weaning duration with fewer manual ventilator adjustments when compared with P-ACV In a previous study, we used ASV only in the weaning period of patients with COPD and found a reduction in the weaning duration  This is the first randomized controlled study that used ASV from intubation until extubation : additional reduction in the duration of MV until weaning ( ∵ ASV automatically switches to PSV when spontaneous activity is detected  better patient ventilator interaction and earlier recognition of extubation readiness)

Discussion Limitation single center study  difficult the generalizability of the results to other centers and patient groups although the staff in charge of the patients were blind to the aim of the study, it was impossible to blind both groups sample size calculation was done according to the ventilation duration of all patients in our ICU (including ARDS) because of technical difficulties  not have the chance to record physiologic data (inspiratory pressure, Vt, RR, inspiratory and expiratory times, static lung compliance, inspiratory resistance, esophageal pressure, and auto-PEEP)

Conclusion ASV may have a positive impact on preparing patients for weaning by shortening the total MV and weaning duration with a fewer number of manual settings of the ventilator Further studies are needed to test the positive impact of these new technologies on outcomes such as patient ventilator interaction, patient comfort, ICU cost, and mortality