[The assessment of correlation between mean arterial pressure and intraoperative bleeding during endoscopic sinus surgery in patients with low heart rate].
Induced controlled hypotension is a standard method aimed at decreasing intraoperative bleeding and achieving good operative field conditions. Low hemodynamic parameters during the operation are related to increased risk of brain hypoperfusion and injury to hypoxia-sensitive nerve cells. The purpose of this study was to find the mean arterial pressure (MAP) that preserves good operative conditions at low heart rate (HR) during endoscopic sinus surgery. Twenty eight patients ASA I-II were anesthetized using remifentanil and sevoflurane. The anesthetist was attempting to keep the heart rate around 60 b/min. tried to diminish the MAP gradually until good operative field conditions were achived. The surgeon blinded to the HR and MAP values rated the bleeding in the operative field on the basis of Fromm and Boezzart scale. Spearman rank correlation coefficient was used to assess the statistical dependence between the variables. The best operative conditions were achieved in patients with the lowest MAP and HR. By keeping the HR at the level of 60 b/min in about 40% of patients very good and good operative field conditions were achieved at MAP higher than 65 mm Hg. There was a significant and strong correlation between the operative field conditions and MAP (Spearman rank correlation test, R = 0.54 p = 0.003). With the stable low heart rate at the minimal physiological values the bleeding in the operative field depends on MAP. Keeping HR around 60 b/min there is no need to decrease the MAP to dangerously low levels to achieve good operative field conditions in great proportion of patients.