Acute smoking increases ST depression in humans during general anesthesia

We tested the hypothesis that acute smoking is associated with ST segment d epression during general anesthesia in patients without ischemic heart dise ase. The carbon monoxide (CO) concentration in expired gas and hemodynamic data was measured during general anesthesia for noncardiac or nonperipheral vascular surgery in patients without symptoms or evidence of ischemic hear t disease, increased expired CO concentrations are indicators of recent smo king. Logistic regression analysis identified significant predictors of ST segment depression greater than or equal to 1 mm. Both rate pressure produc t (odds ratio 1.20 for each increase of 1000, 95% confidence interval = 1.0 4-1.41, P = 0.007) and expired CO concentration (odds ratio 1.05 for each p art per million increase, 95% confidence interval = 1.03-1.08, P = 0.001) w ere significant predictors of ST segment depression when considered simulta neously. Males demonstrated a lower probability of having an episode of ST depression (odds ratio = 0.16, P = 0.01),but this did not change the relati onship between rate pressure product and CO as predictors of ST depression. Approximately 25% of chronically smoking patients smoked on the morning of surgery despite instructions not to smoke. Implications: Patients under ag e 65 without symptoms of ischemic heart disease who smoked shortly before s urgery had more episodes of rate pressure product-related ST segment depres sion than nonsmokers, prior smokers, or chronic smokers who did not smoke b efore surgery. Females were at greater risk of ST depression than males.