Inhaled nitric oxide administration during one-lung ventilation in patients undergoing thoracic surgery

Objective: To evaluate the effects of inhaled nitric oxide (iNO) on hemodyn amics and oxygenation during one-lung ventilation (OLV) in the lateral decu bitus position in patients undergoing elective thoracic surgery. Design: Prospective study. Setting: University hospital. Participants: Thirty consecutive patients scheduled for thoracotomy. Interventions. Anesthesia consisted of thoracic epidural analgesia combined with general anesthesia (isoflurane, fentanyl, and vecuronium bromide). Sy stemic and pulmonary circulations were monitored with a radial artery cathe ter and a pulmonary artery catheter. Inhaled NO, 40 ppm, was administered d uring OLV, and the inhaled gas mixture was monitored for NO and nitrogen di oxide (NO2). Hemodynamic and oxygenation data were collected before and dur ing inhaled NO administration. Measurements and Main Results: Inhaled NO caused a reduction of pulmonary v ascular resistance index from 249 +/- 97.6 dyne . sec . cm(-5) to 199.3 +/- 68.9 dyne . sec . cm(-5) (p < 0.05), without effects on systemic hemodynam ics or impairment of oxygenation. A stratification of the patients accordin g to Values of O-S/O-T (<30%, 30% to 44%, greater than or equal to 45%), Pa O2/fraction of inspired oxygen (greater than or equal to 200, 100 to 199, < 100), and pulmonary hypertension (mean pulmonary arterial pressure <24 or g reater than or equal to 24 mmHg) showed that inhaled NO causes a significan t reduction of mean pulmonary artery pressure in patients with pulmonary hy pertension, mainly as a result of a reduction of pulmonary vascular resista nce index, and improves oxygenation by reducing intrapulmonary shunt in pat ients with severe hypoxemia during OLV. Conclusions: Inhaled NO administration neither significantly decreased mean pulmonary arterial pressure in patients with normal pulmonary artery press ure nor improved oxygenation in nonhypoxic patients. Nevertheless, inhaled NO is effective in patients with pulmonary hypertension and hypoxemia durin g OLV. Copyright (C) 2001 by W.B. Saunders Company.