[BNP measurement for perioperative management].

BACKGROUND: It is difficult to evaluate the tolerance to anesthesia of patients undergoing operations, who have risk factors of congestive heart failure, such as hypertension, old age or various cardiac diseases. BNP (B type natriuretic peptide) is a useful biomarker as a screening tool for LV dysfunction. Therefore we hypothesized that the measurement of BNP may be useful for perioperative management of these patients.

METHODS: Subjects were 101 (58 male and 43 female) gastro-intestinal cancer patients, aged 30 to 91 years (mean 63.9 +/- 12.4) scheduled for intraperitoneal surgery. All patients' plasma BNP concentrations were measured when the patient agreed to the operation. Forty-five patients were enlisted for remeasurements on 2 or 4 postoperative days. We checked patients' backgrounds, perioperative circulatory characteristics and cardiac events. The relationship of BNP to other characteristics and cardiac events were analyzed.

RESULTS: The preoperative mean BNP of patients under 55 years of age (n=20) was 20.4, in patients age 55 to 74 (n=60) it was 30.4, and in patients 75 years and over (n=21) it was 162.1. BNP in elderly patients was higher than in the younger. The mean BNP of the 44 patients with some complications (hypertension, ECG abnormality, cardiac disease etc.) was 97.8, as compared to 23.3 in the 57 patients without complications. The BNP was higher in patients who were elderly, had some cardiac disease, lower exercise capacity, chest X ray abnormality or who needed an echo cardiographic examination. Among the 45 patients who were checked pre and postoperatively, 19 patients' BNP increased postoperatively, while 26 patients showed no change or decrease. Excluding 2 patients, with newly onset congestive heart failure during the postoperative period, the preoperative mean BNP was 63.5, and the postoperative mean BNP was 54.6. During the perioperative period, there was no significant change of BNP. There was no relationship between the BNP and perioperative circulatory characteristics or cardiac events. There were 5 cases with high BNP levels (> 300). None of these patients had cardiac symptoms, and they had normal LV systolic function. It is probable that these patients had chronic heart failure due to LV diastolic dysfunction and risks of perioperative heart failure.

CONCLUSIONS: We cannot predict any circulatory characteristics and cardiac events from preoperative BNP measurement; however BNP measurement is useful for screening asymptomatic chronic heart failure due to LV diastolic dysfunction.