Abstract

AIM: There are several studies suggesting that the most favorable flow pattern for Chronic Obstructive Pulmonary Disease (COPD) patients receiving invasive mechanical ventilation (IMV) is the decelerating waveform. The aim of this study was to compare the effects of volume controlled decelerating flow ventilation (VCV-DF) with pressure controlled ventilation (PCV) and to investigate whether if sinusoidal waveform (VCV-SF) has an additive effect on gas exchaııge and pulmonary mechanics in COPD patients during IMV. MATERIAL AND METHOD: A group of 32 patients with COPD was studied. All patients received ventilation with a microprocessor ventilator (model PB-7200; Puritan-Bennett Corp; Carlsbad, CA). After 12 hours of admission to the ICU, VCV-DF, VCV-SF and PCV were applied respectively for 30 minutes. At the end of each application, peak inspiratoıy pressure (PIP), mean airWay pressure (MAP), plateau pressure (PP), auto-PEEP (PEEPi) and static pulmonary compliance (Cst) measurements, heart rate (HR) and arterial blood pressure (BP) were monitored and arterial blood gas analysis were recorded. FINDINGS: With tidal volume, inspiratory time, inspiratory frequency and Fi02 being kept constant, PIP was significantly higher in VCV-SF mode (p< 0.01). Pa02/ Fi02 ratio was detected higher in VCV-SF mode, PIP 1 eve Is were lower and Cst values were higher in PCV mode but this differences were not statistically significant. MAP, PP, PEEPi, arterial Ph, PaC02, HC03, HR and BP measurements did not show any significant differences among the three ventilation modes. CONCLUSION: This study suggested that the most favorable and safe ventilation mode for COPD patients requirirıg IMV is primarily PCV, then VCV-DF. Another outcome is that the sinusoidal waveform has no additive effect on pulmonary mechanics and gas exchange in this group of patients.