Risk factors for intraoperative hypotension during thyroid surgery

Background: Hypotension is a common adverse effect of IV anaesthetics, especially during the induction of anaesthesia. The aim of our study was to determine the incidence and risk factors for intraoperative hypotension (IOH) in thyroid surgery, as well as to determine whether and to what extent IOH affects the occurrence of postoperative hypotension. Material/Methods: The study included 1252 euthyroid patients, ASA 2 and ASA 3 status (American Society of Anesthesiologists physical status classification), who had thyroid surgery between 2007 and 2011. IOH was defined as a decrease in systolic blood pressure of >20% of baseline values. We studied the influence of demographic characteristics (sex, age, body mass index-BMI), comorbidity, type and duration of surgery, and anaesthesia on the occurrence of IOH. Univariate and multivariate logistic regression were used to determine predictors of occurrence of IOH. Results: IOH was registered in 6.5% of patients. The most common operation was thyroidectomy. Patients with IOH were younger, had lower BMI, and significantly less often had hypertension as a coexisting disease. The multivariate regression model identified BMI and the absence of hypertension as a coexisting disease, and as independent predictors of occurrence of IOH. Significantly more patients with IOH had postoperative hypotension (9.9% vs. 2.4%, p=0.000). Conclusions: IOH is common, even during operations of short duration and with minimal bleeding. It is necessary to pay special attention to these patients, given that many of these patients remained hypotensive during the postoperative period.