Hyperventilation versus standard ventilation for infants in postoperative care for congenital heart defects with pulmonary hypertension

Abstract

Purpose: In infants undergoing surgery for cardiac defects with left-to-right shunt, a hyperventilation strategy has been applied to prevent pulmonary hypertensive crisis (PHC). Hyperventilation with a large tidal volume and/or higher airway pressure, however, may be detrimental to the lung. This randomized study compared the effects of hyperventilation versus standard ventilation. Methods: We enrolled 22 infants with a preoperative pulmonary-to-systemic blood pressure ratio of more than 0.7. Hyperventilation, with a tidal volume of 10-12 ml·kg-1 to keep PaCO2 between 30 and 35 mmHg, was randomly applied in 11 patients for 16 h or more. The other 11 patients were randomly assigned to standard ventilation, with a 6- to 8- ml·kg-1 tidal volume. Results: The peak inspiratory pressure was higher (20 ± 3 vs 18 ± 2 cmH2O; P = 0.018), and PaCO2 (34 ± 5 vs 42 ± 7 mmHg; P = 0.003) and positive end-expiratory pressure (3 ± 0 vs 5 ± 0; P < 0.0001) were significantly lower in the hyperventilation than in the standard ventilation group. The PaO2/inspiratory fraction of oxygen (F1O2 ratio decreased from 244 ± 160 mmHg at the onset of postoperative ventilation, to 177 ± 96 mmHg at 24 h (P = 0.038) in the hyperventilation group, versus a decrease from 240 ± 89 to 220 ± 97 mmHg in the standard ventilation group not significant (NS). Serum interleukin (IL)-6 level, measured at 24 h postoperatively, was significantly lower (P = 0.02) in the standard ventilation than in the hyperventilation group, suggesting an attenuated postoperative systemic inflammatory response. A single patient in each group developed PHC. Conclusion: Hyperventilation may cause lung injuryand systemic inflammation in infants with pulmonary hypertension undergoing corrective heart surgery. © Japanese Society of Anesthesiologists 2009.