[Feasibility study of controlled hypotension induced with combination of propofol and desflurane in craniotomy].

OBJECTIVE: To evaluate the feasibility of controlled hypotension induced with combination of propofol and desflurane in craniotomy.

METHODS: Thirty-five ASA I approximately II patients undergoing elective craniotomy were randomly selected. Anesthetic induction was achieved with midazolam, thiopental, fentanyl, and vecuronium. Anesthesia was maintained with infusion of propofol and inhalation of desflurane. The propofol infusion rate and desflurane inhalation concentration were raised during isolation and resection of the tumors so that the mean arterial pressure (MAP) was reduced by 30% - 40% and > 50 mm Hg and maintained at this level for 30 - 45 min. After the resection of tumor, the propofol infusion rate and desflurane inhalation concentration were reduced so as to let the MAP increase to normal level. MAP, heart rate (HR), cerebrospinal fluid pressure (CSFP), propofol infusion rate, and inhalation concentration of desflurane were recorded before controlled hypotension, at the 1st, 3rd, 5th, 10th, 20th and 30th minute of the procedure of controlled hypotension, and just before the increase of blood pressure and 1, 3, 5, 10, 20, 30, 40 and 50 minutes after controlled hypotension. The awakening status was observed. Arterial and jugular bulb venous blood samples were taken before, during and after hypotension and the arterial to jugular bulb venous oxygen content difference [D(a-jv)O(2)] and cerebral oxygen extraction rate (ERO(2)) were measured.

RESULTS: The time needed to reach controlled hypotension was 6 - 35 minutes and that needed to reach the normal blood pressure was 12 - 41 minutes. The propofol infusion rate and inhalation concentration of desflurane needed to maintain controlled hypotension were 51 micro g x kg(-1) x min(-1) +/- 27 micro g x kg(-1) x min(-1) and 6.4% +/- 4.1% respectively. HR increased significantly in the initial stage and returned to baseline value after 3 - 14 min during the controlled hypotension. CSFP decreased significantly after incision of dura mater of brain and during controlled hypotension (P < 0.05). The recovery time after weaning from propofol infusion and desflurane inhalation until eye opening in response to order and autonomous breathing was 25 min +/- 19 minutes. The time needed to regain autonomous breathing with the tidal volume > 300 ml/time was 17 min +/- 10 minutes. Compared with those before hypotension, the SjvO(2) was increased significantly, and D(a-jv)O(2) and ERO(2) were decreased significantly during hypotension (P < 0.05). CaO(2) and CjvO(2) remained unchanged throughout the process of hypotension (P > 0.05).

CONCLUSION: With low propofol infusion rate and low desflurane inhalation concentration, rapid hypotension, rapid recovery of breathing after operation, a short recovery time from anesthesia, and decreased CSFP and brain oxygen metabolism, controlled hypotension with propofol infusion and desflurane inhalation is suitable to intracranial surgery.