Comparison of two ventilation modes in post-cardiac surgical patients

Abstract

Background:The cardiopulmonary bypass (CPB)-associated atelectasis accounted for most of the marked post-CPB increase in shunt and hypoxemia. We hypothesized that pressure-regulated volume-control (PRVC) modes having a distinct theoretical advantage over pressure-controlled ventilation (PCV) by providing the target tidal volume at the minimum available pressure may prove advantageous while ventilating these atelactic lungs.Methods:In this prospective study, 36 post-cardiac surgical patients with a PaO2/FiO2 (arterial oxygen tension/Fractional inspired oxygen) < 300 after arrival to intensive care unit (ICU), (n = 34) were randomized to receive either PRVC or PCV. Air way pressure (Paw) and arterial blood gases (ABG) were measured at four time points [T1: After induction of anesthesia, T2: after CPB (in the ICU), T3: 1 h after intervention mode, T4: 1 h after T3]. Oxygenation index (OI) = [PaO2/ {FiO2 × mean airway pressure (Pmean)}] was calculated for each set of data and used as an indirect estimation for intrapulmonary shunt.Results:There is a steady and significant improvement in OI in both the groups at first hour [PCV, 27.5(3.6) to 43.0(7.5); PRVC, 26.7(2.8) to 47.6(8.2) (P = 0.001)] and second hour [PCV, 53.8(6.4); PRVC, 65.8(7.4) (P = 0.001)] of ventilation. However, the improvement in OI was more marked in PRVC at second hour of ventilation owing to significant low mean air way pressure compared to the PCV group [PCV, 8.6(0.8); PRVC, 7.7(0.5), P = 0.001].Conclusions:PRVC may be useful in a certain group of patients to reduce intrapulmonary shunt and improve oxygenation after cardiopulmonary bypass-induced perfusion mismatch.

Comparison of pressure vs. volume controlled ventilation on oxygenation parameters of obese patients undergoing laparoscopic cholecystectomy

“… 14 Samantaray and Hemanth demonstrated similar results to our study especially in later phase of anesthesia. 15 In this prospective study, 35 patients post cardiac surgery patients were randomized to receive PRVC or PCV. There was a steady and significant improvement in oxygenation index in both groups at the first and second hours of ventilation.…”

The application of Pressure-regulated volume controlled ventilation mode in Video-assisted Thoracoscopic Surgery pulmonary segmentectomy

“…The actual inspiration pressure of the next ventilation is 75% of the above calculated value. After several ventilation, the actual tidal volume can be consistent with the preset tidal volume [13,14]. Since the waveform of inspiratory velocity is a deceleration wave, the vortex of gas can be reduced when the patient's airway resistance is large, so the pressure consumption and peak inspiratory pressure can be reduced while the preset tidal volume is ensured [15].…”

“…According to the lung protective ventilation strategy, the goal of ventilation management is to minimize ventilator-associated lung injury, and PRVC mode is well consistent with this strategy [10,11]. On the basis of ensure the preset tidal volume and respiratory function of automatic continuous monitoring lung compliance and volume/pressure relationship, PRVC ventilation mode reduce airway pressure as much as possible, so as to reduce the pressure of the positive pressure ventilation [12].…”

Comparison of respiratory and hemodynamic stability in patients with traumatic brain injury ventilated by two ventilator modes: Pressure regulated volume control versus synchronized intermittent mechanical ventilation

“…[11] Although in an experimental work using ventilation simulations, using PRVC mode was not considered to provide appropriate TVs for severely obstructed patients;[12] in other situations such as postcardiac surgical patients, oxygenation index has been superior in PRVC mode of ventilation in recovery period. [13] Other pressure modes of mechanical ventilation may have better patient-ventilator synchrony and adequate gas exchange and less ventilator-induced lung injury. [5141516]…”