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

Objective: To 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.

Methods: This was a randomized study with a 2-group, pre-test, post-test experimental design. Effects of hyperinflation were studied on static compliance (C(stat)), dynamic compliance (C(dyn)), oxygenation (Pao(2):Fio(2)), partial pressure of carbon dioxide in arterial blood (Paco(2)), 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.

Results: No significant differences were found between the groups. Significant improvements were found in oxygenation at both 1minute and 20minutes after MHI, but only at 1minute after VHI (P < .05). VHI led to improved C(dyn) (P < .05).

Conclusion: In 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. Paco(2) and pH were maintained by both.