Evaluation of Exhaled Nitric Oxide in Patients Undergoing Myocardial Revascularization with Cardiopulmonary Bypass

Perioperative changes in exhaled nitric oxide during oesophagectomy

INTRODUCTION

Oesophagectomy is a major surgical procedure, associated with high rates of postoperative cardiopulmonary morbidity, that is in part due to the frequent requirement for periods of intraoperative one-lung ventilation (OLV). The current pilot study aims to investigate variation in exhaled NO levels during oesophagectomy with emphasis on the response to OLV and correlation to physiological variables and clinical outcomes.

METHODS

Breath-to-breath concentrations of NO were analysed in patients undergoing oesophagectomy at various stages of two-lung ventilation. Furthermore, we also analysed the effects of OLV both in the selectively ventilated and collapsed lungs.

RESULTS

Twenty-four patients were recruited to the study (17 male, 60.2 ± 12.8 years). Regarding two-lung ventilation, the baseline levels of NO (2.9 ppb), tended to increase after re-inflation of the collapsed lung (3.5 ppb, P = 0. 888) and decreased at 2 h (2.1 ppb, P = 0.022) and 12 h (2.2 ppb, P = 0.733) postoperatively. Compared to baseline, selective measurements of NO at the end of OLV demonstrated a significant reduction of NO levels in the ventilated lung (1.6 versus 3.1 ppb, P = 0.028), whereas re-inflation of the collapsed lung revealed higher levels of NO (3.4 versus 2.7 ppb, P = 0.657). Exhaled NO correlated significantly with systolic blood pressure and lactate (P < 0.007). Exhaled NO levels tended to be higher at all perioperative time points in patients who developed postoperative respiratory complications (P > 0.05).

CONCLUSION

This study highlights effects of oesophagectomy and OLV on exhaled concentrations of NO. The observed variations may be related to differential ventilation during OLV altering the complex balance between synthesis and consumption of NO as well as local and generalised tissue injury associated with this surgery. Findings should prompt further larger studies to establish the relationship between exhaled NO and lung injury both during and after oesophagectomy and one-lung ventilation.

Exhaled nitrite/nitrate levels as a marker of respiratory complications after heart valve surgery

PURPOSE

The purposes of this study are to measure the nitric oxide metabolites nitrite and nitrate (NOx) in the exhaled breath condensates (EBCs) of patients submitted to heart valve surgery and to assess the correlation between NOx levels and postoperative respiratory complications.

MATERIALS AND METHODS

Exhaled breath condensate and blood samples were collected from each patient during spontaneous breathing preoperatively, during invasive mechanical ventilation in the fourth hour after surgery and 12, 24, 48, and 72 hours after the operation. Nitrite and nitrate levels in the EBC and serum were measured by chemiluminescence.

RESULTS

Thirty-two patients were included in the study. In patients who presented with postoperative respiratory complications, the postoperative levels of NOx were significantly higher in the EBC from the fourth postoperative hour compared with those who experienced uneventful postoperative periods (P = .027). However, the preoperative and postoperative serum levels of NOx were not significantly different in between-group analyses (P = .995).

CONCLUSION

Our results suggest that the postoperative NOx level in the EBC is an early marker of respiratory complications after heart valve surgery. Additional studies using large cohorts are necessary to corroborate our results and to better define the clinical usefulness of assessing NOx in the EBC after cardiac surgery.