Comparison of free hexafluoro-isopropanol concentrations in whole blood of patients inhaling different concentrations of sevoflurane: the relationship with emergence agitation

Objective To compare the free hexafluoro-isopropanol (HFIP) concentrations in whole blood of patients inhaling different concentrations of sevoflurane and further evaluate the relationship with emergence agitation. Methods Forty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes, aged 18-64 yr, scheduled for elective laparoscopic gastrointestinal surgery, were divided into 3 groups according to the inhaled conentration of sevoflurane using a random number table: 0.86% group (group S1, n=13), 1.71% group (group S2, n=14) and 2.57% group (group S3, n=13). In S1, S2 and S3 groups, the corresponding concentrations of sevoflurane were inhaled, remifentanil (target concentration 4-6 ng/ml) was given by target-controlled infusion, and propofol (4-12 mg·kg-1·h-1) and cisatracurium 0.1 mg·kg-1·h-1 were infused intravenously at the same time, and sevoflurane was inhaled for 3 h, and then inhalation was stopped.At 30 min and 1, 2 and 3 h of sevoflurane inhalation and 1, 3 and 5 h after stopping inhalation, central venous blood samples were collected for determination of free HFIP concentrations in whole blood by the method of two-stage headspace equilibration.The recovery time for spontaneous breathing, time for eye opening on verbal command, extubation time and development of agitation and moderate pain within 4 h after extubation were recorded. Results Free HFIP concentrations in whole blood peaked at 1 of inhalation, then gradually decreased, and the concentrations decreased continuously after stopping inhalation in the three groups (P 0.05). Conclusion Free HFIP concentrations in whole blood increase with the increase in inhaled sevoflurane concentrations, however, production of free HFIP is markedly inhibited when the inhaled concentration reaches 2.57%, and free HFIP concentrations in whole blood decrease; free HFIP had nothing to do with the emergence agitation in patients. Key words: Anesthetics, inhalation; 2-Propanol; Anesthesia recovery period; Agitation