Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1998
Comparative StudyThe pharmacokinetics of vecuronium in male and female patients.
To evaluate the effect of gender on the pharmacokinetics of vecuronium, we studied 30 patients (15 male and 15 female) undergoing elective plastic surgery with anticipated surgical blood loss of <300 mL under general anesthesia. General anesthesia was induced with thiopental 4-6 mg/kg and fentanyl 2-4 microg/kg and was maintained with 60% nitrous oxide in oxygen and an end-tidal concentration of 1.5%-2% enflurane. After a 2-min infusion of vecuronium 100 microg/kg, a modified fluorometric assay was used to determine the plasma concentrations of vecuronium for 5 h. The results showed that, compared with women, the plasma concentrations of vecuronium in men were significantly lower during the first 20 min and that the disposition kinetics of vecuronium can be best described mathematically by a three-compartment open model in the two groups. The volume of the central compartment and the volume of distribution at steady state were 39.6 +/- 8.6 and 164.8 +/- 29.3 mL/kg, respectively, in women. These values increased significantly to 54.4 +/- 14.4 and 201.4 +/- 75.8 mL/kg in men (P < 0.05). When the data were calculated on the basis of ideal body weight, the volume of distribution of vecuronium was also different between men and women (P < 0.05. The half-lives of fast distribution and distribution, the elimination half-life, mean residual time, area under the plasma-concentration curve, and plasma clearance were not different between the two groups. We conclude that the pharmacokinetics of vecuronium are significantly different between genders and that and men have the greater volume of distribution of vecuronium. ⋯ The authors found that, compared with women, men had lower plasma concentrations of vecuronium after the i.v. administration of vecuronium and a larger volume of distribution of vecuronium. The pharmacokinetic differences may be related to the differences in the sensitivity to vecuronium between genders.
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Anesthesia and analgesia · Jun 1998
The effect of pneumoperitoneum on intraocular pressure in rabbits with alpha-chymotrypsin-induced glaucoma.
Increased intraperitoneal pressure is associated with physiological changes including alterations of intraocular pressure (IOP). We have previously shown that IOP is not adversely affected by increased intraperitoneal pressure up to 15 mm Hg in women with no preexisting eye disease. The aim of this study was to measure IOP changes associated with increased intraperitoneal pressure (up to 15 mm Hg) of 2 h duration in 12 rabbits with alpha-chymotrypsin-induced glaucoma. A reliable model of glaucoma was created by injecting alpha-chymotrypsin into the posterior chamber of the right eye in 12 rabbits. Thereafter, 5 of the 12 rabbits with glaucomatous eyes were treated with topical timolol. The left eye was used as a control. During pentobarbital general anesthesia, increased intraperitoneal pressure up to 15 mm Hg was created by intraperitoneal CO2 insufflation. Body temperature and expired CO2 were kept constant throughout the study. IOP measurements were made using an electronic pneumotonometer. IOP, mean arterial pressure, heart rate, and central venous pressure were recorded in head-up and head-down positions before, during, and after increased intraperitoneal pressure. The IOP of both eyes, in both treated and untreated rabbits, increased significantly from baseline only when increased intraperitoneal pressure associated with the head-down position resulted in a significant increase in central venous pressure. However, the IOP increase remained within the diurnal range. The major finding of this study is that, in a reliable model of glaucoma, CO2 pneumoperitoneum was associated with an increase in IOP when a head-down position was combined with pneumoperitoneum. ⋯ In rabbits with alpha-chymotrypsin-induced glaucoma, increased intraperitoneal pressure (up to 15 mm Hg) resulted in a significant intraocular pressure increase when pneumoperitoneum was associated with the head-down position. However, the intraocular pressure increase remained within the diurnal range.