Measurement of respiratory nitric oxide in patients undergoing cardiopulmonary bypass

L Pardeshi¹, J Hayden-Smith¹, T Small², P Arnold¹, A Fisher² and P Corris²

¹Department of Cardiothoracic Anaesthesia and Cardiothoracic Centre Freeman Hospital and University of Newcastle, Newcastle upon Tyne, UK

²Department of Respiratory Medicine, Freeman Hospital and University of Newcastle, Newcastle upon Tyne, UK

from 18th Autumn Meeting of the Association of Cardiothoracic Anaesthetists
London, UK. 16 November 2001

Critical Care 2001, 5(Suppl 4):7doi:10.1186/cc1439

Published:

7 November 2001

Introduction

Aim of the present study was to study the effects of cardiopulmonary bypass (CPB) on endogenous nitric oxide (NO) from the lungs and to exclude mass gas flow by measuring the NO levels in the trachea held during end inspiration [1,2].

Method

Twenty adult patients undergoing elective surgery involving CPB under mild hypothermia were prospectively investigated. Patients likely to have pre-existing pulmonary hypertension, cardiac failure or lung disease (including controlled asthma) were excluded. Measurements were recorded before and after CPB. After preoxygenation with 100% oxygen for 3 min, a non-Teflon catheter was introduced into the endo-tracheal (E-T) tube via an airtight valve so that the tip of the catheter was within 3 cm of the E-T tube tip. Respiration was held during end inspiration until a plateau was seen on the nitric oxide and carbon dioxide traces. Exhaled NO was measured using a rapid highly sensitive chemiluminescence analyser (LR2000, version 2.2; Logan Research, Rochester, UK).

Results

Two-way analysis of variance, with patients and times as factors showed that the peak concentration of NO in the major airways of patients following CPB was significantly lower as compared to pre-bypass samples. End-inspiratory NO levels decreased from 7.89 ± 0.5 ppb (mean ± STD) to 4.63 ± 0.32 ppb (P < 0.05).

Conclusions

There is a decrease in the plateau level of exhaled nitric oxide in the major airways following CPB. The reason for these reduced levels remains uncertain. The results suggest a reduction in endogenous nitric oxide production from the lungs.

References

Hyde RW, Geigel EJ, Olszowka AJ, Krasney JA, Forster RE 2nd, Utell MJ, Frampton MW: Determination of production of nitric oxide by lower airways of humans: theory.
J Appl Physiol 1997, 82:1290-1296. PubMed Abstract | Publisher Full Text
Brett SJ, Quinlan GJ, Mitchell J, Pepper JR, Evans TW: Production of nitric oxide during surgery involving cardiopulmonary bypass.
Crit Care Med 1998, 26:208-209. PubMed Abstract | Publisher Full Text

This article is part of the supplement: 18th Autumn Meeting of the Association of Cardiothoracic Anaesthetists