Background-Water ingestion raises blood pressure substantially in patients with perturbed autonomic control and more modestly in older subjects. It is unclear whether prophylactic water drinking improves orthostatic tolerance in normal healthy adults. Methods and Results-Twenty-two healthy subjects, 18 to 42 years of age, with no history of syncope underwent head-up tilt-

We studied the effect of the inspired isoflurane concentration (C_Iiso) on the pharmacokinetics of isoflurane uptake in the brain by comparing the isoflurane concentration in internal jugular-bulb blood (Jiso) with that in arterial blood (Aiso), and analyzed this by gas chromatography. Sixteen patients (aged 43–76 years) undergoing colorectal surgery were enrolled, and anesthesia was maintained with a constant C_Iiso of either 1% (group 1, n = 8) or 2% (group 2, n = 8) during the 1st hour of isoflurane anesthesia. Under constant volume-controlled ventilation, we measured the C_Iiso and the end-tidal isoflurane concentration (C_Eiso) at the mouthpiece by infrared analysis. Our results demonstrate that it takes 40 min for the brain tissue concentration to equal Aiso for 1% C_Iiso, and 50 min for 2% C_Iiso. The Aiso (and/or Jiso) for 2% C_Iiso was approximately double when compared to that for 1% C_Iiso. Except during the initial wash-in period of the functional residual capacity in the first 3 min, the differences between C_Iiso and C_Eiso revealed that the body uptake of isoflurane for 2% C_Iiso was twice that for 1% C_Iiso. These results demonstrate that the pharmacokinetics of isoflurane uptake in the brain is time-dependent for Jiso to equal Aiso, and the midpoint between Aiso and Jiso (likely representing the isoflurane concentration in brain tissue) was dependent on C_Iiso.

Opioid prescriptions and expenditure increased steadily from 2002 to 2007 in Taiwan, as in nearby Asian countries, but remained much lower than in developed countries. Pethidine (meperidine) was predominantly prescribed to noncancer patients, whereas morphine and fentanyl were mainly prescribed for cancer patients.

OBJECTIVES:To determine the awakening arterial blood concentration of desflurane and its relationship with the end-tidal concentration during emergence from various durations of general anesthesia.METHOD:In total, 42 American Society of Anesthesiologists physical status class I-II female patients undergoing elective gynecologic surgery were enrolled. General anesthesia was maintained with fixed 6% inspiratory desflurane in 6 l min-1 oxygen until shutoff of the vaporizer at the end of surgery. One milliliter of arterial blood was obtained for desflurane concentration determination by gas chromatography at 20 and 10 minutes before and 0, 5, 10, 15, and 20 minutes after the discontinuation of desflurane and at the time of eye opening upon verbal command, defined as awakening. Concentrations of inspiratory and end-tidal desflurane were simultaneously detected by an infrared analyzer.RESULTS:The mean arterial blood concentration of desflurane was 1.20% at awakening, which correlated with the awakening end-tidal concentration of 0.96%. The mean time from the discontinuation of desflurane to eye opening was 5.2 minutes (SD = 1.6, range 3-10), which was not associated with the duration of anesthesia (60-256 minutes), total fentanyl dose, or body mass index (BMI).CONCLUSIONS:The mean awakening arterial blood concentration of desflurane was 1.20%. The time to awakening was independent of anesthetic duration within four hours. Using well-assisted ventilation, the end-tidal concentration of desflurane was proven to represent the arterial blood concentration during elimination and could be a clinically feasible predictor of emergence from general anesthesia.