The Use of High Frequency Percussive Ventilation in Postoperative Cardiac Surgery Patients Significantly Improves Gas Exchange Without Impairment of Hemodynamics

Abstract

Background:

We sought to determine if HFPV improves gas exchange in postoperative open heart cardiac surgery patients.

Methods:

Patients were ventilated after surgery with HFPV for 2 h, then switched to a conventional ventilator, using the adaptive support ventilation (ASV) mode for weaning. ABGs were performed for the first and second hour on HFPV, and for the first hour on conventional ventilation, FIO₂ was maintained at 0.70 on both VDR and conventional ventilator. Invasive hemodynamic data was collected utilizing right heart pulmonary catheter and arterial lines. After arrival from the OR the patients were on the VDR-4 ventilator. ABGs were monitored Q1H until patients were weaned and extubated. After 2 h patients were transferred to a conventional ventilator for weaning and extubation. The mode used was Adaptive Support Ventilation (ASV), 22 patients were included in the study data for analysis.

Results:

First hour mean P/F ratio was observed on HFPV, being significantly higher than the first hour mean P/F ratio on conventional ventilation (mean difference 162.29 mm Hg, 95 % CI 97.07-240.99, P<0.001). This difference was increased when comparing the second hour mean P/F ratio on HFPV with the first hour mean P/F ratio on conventional ventilation (mean difference 205.39 mm Hg, 95% CI 143.14-267.63, P<0.001).

Conclusions:

There was a statistically significant difference in P/F ratio between the first hour on HFPV and conventional ventilation, as well as the second hour respectively (P<0.001). Thus, gas exchange based on P/F ratio at similar MAP and pulmonary artery wedge was significantly improved with HFPV compared with conventional ventilation, and improved further over the second hour of HFPV compared to conventional ventilation. The significant gains in P/F ratio were lost over one hour when switched to conventional ventilation. HFPV provided significantly better gas exchange and thus may have reduced shunting induced by open heart cardiac surgery. In this population of postoperative open heart cardiac surgery patients, HFPV was able to significantly improve gas exchange, as reflected by P/F ratio and P(A-a)O₂ without any hemodynamic consequence.

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