Preoperative ultra short-term entropy predicts arterial blood pressure fluctuation during the induction of anesthesia.

Abstract

In this study, we sought to determine whether the preoperative nonlinear index of heart rate variability, ultra short-term entropy (UsEn), could predict cardiovascular responses to the induction of general anesthesia. UsEn was estimated by a linearized version of the nonlinear least squares method combined with the maximum entropy spectral analysis method (MemCalc method). Preoperative UsEn of 46 patients (ASA PS 1 or 2, aged 40-60 yr) without a history of hypertension was evaluated using the MemCalc method. Patients were assigned to two groups according to preoperative UsEn (Group LOW; UsEn <45, Group HIGH; UsEn > or =45). Anesthesia was induced with propofol, fentanyl and vecuronium bromide and endotracheal intubation was performed. Hemodynamic fluctuations during the induction of anesthesia were recorded and compared between the two groups. It was found that arterial blood pressure fluctuations during the induction of anesthesia were significantly greater in patients with a low UsEn. UsEn could predict arterial blood pressure fluctuations during the induction of anesthesia.