Comparison of effects of manual versus ventilator hyperinflation on respiratory compliance and arterial blood gases in patients undergoing mitral valve replacement

ObjectiveTo compare the effects of manual hyperinflation (MHI) and ventilator hyperinflation (VHI) delivered to completely sedated and paralyzed patients undergoing mitral valve replacement (MVR) while maintaining minute ventilation.MethodsThis was a randomized study with a 2-group, pre-test, post-test experimental design. Effects of hyperinflation were studied on static compliance (Cstat), dynamic compliance (Cdyn), oxygenation (Pao2:Fio2), partial pressure of carbon dioxide in arterial blood (Paco2), and cologarithm of activity of dissolved hydrogen ions in arterial blood (pH). A sample of 30 patients in the immediate postoperative phase of MVR surgery were included in the study.ResultsNo significant differences were found between the groups. Significant improvements were found in oxygenation at both 1 minute and 20 minutes after MHI, but only at 1 minute after VHI (P < .05). VHI led to improved Cdyn (P < .05).ConclusionIn the immediate postoperative phase of MVR, both techniques produced similar effects on respiratory compliance and oxygenation. MHI produced longer lasting improvements in oxygenation than VHI, whereas VHI produced better improvements in dynamic compliance. Paco2 and pH were maintained by both.