The majority of studies of Nitric Oxide (NO) during one-lung ventilation over the past five years have shown that NO does not cause a significant increase in the mean PaO2. One recent study(1) shows that among patients with hypoxemia (defined here as PaO2/FiO2 <100) there was an increase in mean arterial oxygenation with NO 40ppm. Examining the data shows that a small minority of hypoxemic patients (approximately 25%)will have a clinically useful increase in PaO2 with NO. Examining the data of previous studies(2) it can be seen in other studies that a few patients with borderline hypoxemia will have an increase in PaO2 with NO. Although this does not make NO a useful therapy for hypoxemia during one-lung ventilation it does raise the possibility that it may be possible to identify the minority of patients who respond to NO.
References:
(1)Author
Rocca GD. Passariello M. Coccia C. Costa MG. Di Marco P. Venuta F. Rendina EA. Pietropaoli P

Institution
Istituto di Anestesiologia e Rianimazione, Cattedra di Chirurgia Toracica, University of Rome “La Sapienza,” Azienda Ospedaliera Policlinico Umberto I, Rome, Italy.

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

Source
Journal of Cardiothoracic & Vascular Anesthesia, 15(2):218-23, 2001 April.

Abstract
OBJECTIVE: To evaluate the effects of inhaled nitric oxide (iNO) on hemodynamics and oxygenation during one-lung ventilation (OLV) in the lateral decubitus 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). Systemic and pulmonary circulations were monitored with a radial artery catheter and a pulmonary artery catheter. Inhaled NO, 40 ppm, was administered during OLV, and the inhaled gas mixture was monitored for NO and nitrogen dioxide (NO(2)). Hemodynamic and oxygenation data were collected before and during inhaled NO administration. Measurements and Main Results: Inhaled NO caused a reduction of pulmonary vascular 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 hemodynamics or impairment of oxygenation. A stratification of the patients according to values of Q(S)/Q(T) (<30%, 30% to 44%, >/=45%), PaO(2)/fraction of inspired oxygen (>/=200, 100 to 199, <100), and pulmonary hypertension (mean pulmonary arterial pressure <24 or >/=24 mmHg) showed that inhaled NO causes a significant reduction of mean pulmonary artery pressure in patients with pulmonary hypertension, mainly as a result of a reduction of pulmonary vascular resistance index, and improves oxygenation by reducing intrapulmonary shunt in patients with severe hypoxemia during OLV. CONCLUSIONS: Inhaled NO administration neither significantly decreased mean pulmonary arterial pressure in patients with normal pulmonary artery pressure nor improved oxygenation in nonhypoxic patients. Nevertheless, inhaled NO is effective in patients with pulmonary hypertension and hypoxemia during OLV. Copyright 2001 by W.B. Saunders Company

(2)Authors
Fradj K. Samain E. Delefosse D. Farah E. Marty J.

Institution
UFR Xavier Bichat, Universite Paris VII, Service d’Anesthesiologie, Hopital Beaujon, Clichy, France.

Title
Placebo-controlled study of inhaled nitric oxide to treat hypoxaemia during one-lung ventilation.

Source
British Journal of Anaesthesia. 82(2):208-12, 1999 Feb.

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Abstract
The aim of this prospective, placebo-controlled study was to assess if unilaterally inhaled nitric oxide 20 ppm could treat hypoxaemia during one-lung ventilation. Sixty patients undergoing pulmonary resection using a lateral thoracotomy were allocated randomly to a control or nitric oxide group (NO group). During one-lung ventilation in the lateral decubitus position, the lungs were ventilated mechanically with 90% oxygen–10% nitrogen. After randomization, if PaO2 decreased to less than 9.3 kPa during one-lung ventilation, nitric oxide 20 ppm or nitrogen was added to the inspired gas. The criterion for treatment efficacy was an increase in PaO2 to greater than 9.3 kPa after gas administration. Eight patients in the control group and eight in group NO experienced hypoxaemia during one-lung ventilation. PaO2 was not significantly different in the two groups at the time of gas administration (control group mean 8.0 (SD 0.6) kPa; NO group 8.5 (0.5) kPa). The efficacy criterion was reached in two of eight patients in the control and NO groups. The results of this study showed that inhaled nitric oxide 20 ppm, administered in the dependent lung, was not superior to nitrogen in the treatment of hypoxaemia during one-lung ventilation. Nitric oxide should not be recommended as an alternative to conventional management of hypoxaemia in this condition.