Measurement of respiratory nitric oxide in patients undergoing cardiopulmonary bypass
© BioMed Central Ltd 2001
Published: 7 November 2001
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).
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).
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.
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