Ventilatory and Hemodynamic Effects of High-Frequency Jet Ventilation following Cardiac Surgery

Abstract

Although high-frequency ventilation may command lower airway pressures than does conventional ventilation, with an associated decrease in pulmonary barotrauma, impairment of cardiovascular function has been observed in some studies. We studied the effect of brief periods of high-frequency jet ventilation (HFJV) on hemodynamic function in children after open heart surgery. Method: In a crossover study design, we compared the effects of HFJV and conventional volume ventilation in eight children (2 months to 7 years of age) following open heart surgery. Results: HFJV permitted reduction of peak inspiratory pressure (from 25±5 to 11 ± 3 cm H₂O, P < 0.001) and consequently mean airway pressure (Paw) (from 7 ± 1 to 5 ± 2 cm H₂O, P < 0.01), although part of the decreased Paw was due to a decrease in positive end-expiratory pressure (from 4 ± 1 to 3 ± 1 cm H₂O). Cardiac index was 3.1 ± 0.6 L/min/m² during CV and increased slightly to 3.4 ± 0.4 L/min/m² during HFJV (P < 0.05), but oxygen delivery did not increase significantly (CV 603 ± 153, HFJV 640 ± 155 ml/min/m², P = 0.18) due to a decrease in PaO₂ (CV 107 ± 30 to HFJV 93 ± 26 torr, P < 0.05). There was a significant inverse relationship between the initial cardiac index and its subsequent increase during HFJV (r = -0.79, P < 0.05). Conclusions: These data indicate that short-term HFJV following open heart surgery does not have a deleterious effect on cardiovascular function in clinically stable patients and may be associated with an increase in cardiac index in some.