Comparing the Effect of Adaptive Support Ventilation (ASV) and Synchronized Intermittent Mandatory Ventilation (SIMV) on Respiratory Parameters in Neurosurgical ICU Patients

A clinical trial of volume- versus pressure-controlled intraoperative ventilation during laparoscopic bariatric surgeries

BACKGROUND

Intra-operative ventilation is often challenging in patients with morbid obesity undergoing bariatric surgery.

OBJECTIVES

To test the noninferiority of pressure-controlled ventilation (PCV) to volume-controlled ventilation (VCV) in respiratory mechanics.

SETTING

Bariatric Surgery Center, Iran.

METHODS

In a randomized open-labeled clinical trial, 66 individuals with morbid obesity undergoing laparoscopic bariatric surgeries underwent intraoperative ventilation with either PCV or VCV. The measurements taken were peak and mean airway pressures (H₂O), partial pressure of arterial oxygen (PaO₂), partial pressure of arterial carbon dioxide (PaCO₂) and end-tidal carbon dioxide (CO₂). We additionally collected pulse-oximetric oxygen saturation, inspiratory concentration of oxygen (FiO₂), and hemodynamic variables. Data were analyzed with repeated measures over the time of intubation, after peritoneal insufflation, and every 15 minutes, thereafter up to one hour.

RESULTS

PCV mode was successful to sustain adequate ventilation in 97% of the patients, which was similar to the 94% success rate of the VCV mode. Peak airway pressure increased 6 cmH₂O and end-tidal CO₂ rose by 5 mm Hg after abdominal insufflation in both groups (P = .850 and .376). Alveolar-arterial oxygen gradient similarly increased within 30 minutes after tracheal intubation both in PCV and VCV groups, with small trend of being higher in the VCV group. The ratio of dead space to tidal volumes (VD/VT) did not have a meaningful change (P = .724).

CONCLUSION

PCV was noninferior to VCV during laparoscopic bariatric surgery. Either mode of ventilation could be alternatively used during the anesthesia care of these patients.

Comparisons of Metabolic Load between Adaptive Support Ventilation and Pressure Support Ventilation in Mechanically Ventilated ICU Patients

Purpose

The aim of this study was to compare the metabolic load between adaptive support ventilation (ASV) and pressure support ventilation (PSV) modes in critically ill patients.

Methods

Sequential 20 min ventilation by PSV followed by 20 min ASV in critically ill patients was assessed. ASV was set for full support, i.e., with the minute volume control set at the same level as the minute volume observed during PSV. The trial started from PSV 8 cmH₂O and continued with high (PSV 12 cmH₂O) to low (PSV 0) conditions or low to high conditions, in random order. The oxygen consumption (VO₂), production of carbon dioxide (VCO₂), and energy expenditure (EE) were measured by indirect calorimetry (IC).

Results

Twenty-four patients with critical illness participated in the study. Comparing with the PSV mode, the EE in the ASV mode was lower in the level of PSV 0 cmH₂O (1069 ± 73 vs. 1425 ± 76 kcal), PS 8 cmH₂O (1116 ± 70 vs. 1284 ± 61 kcal), and PS 12 cmH₂O (1017 ± 70 vs. 1169 ± 58 kcal) (p < 0.05). The VO₂, VCO₂, and P0.1 in PSV were significantly higher than those in ASV (p < 0.05). The VO₂, VCO₂, and P0.1 in PSV were significantly higher than those in ASV (.

Conclusion

In patients with critical illness, the application of ASV set for full support was associated with a lower metabolic load and respiratory drive than in any of the studied PSV conditions.