This study aimed to measure the intraocular pressure (IOP) of patients undergoing open surgery in the supine position (control group) and spine surgery in the prone position (spine group) to clarify IOP range and change by posture, determine the risk factors for increased IOP in the prone position, and reduce visual complications after surgery in the prone position.
The purpose of this study is to examine changes in serum and urinary inorganic fluoride (F) concentrations with their effects on renal and hepatic functions after repeated sevoflurane anesthesia with relatively short time interval. Eight patients received sevoflurane anesthesia twice within 7 days for gynecological surgery. Serum and urine F levels before induction, 0.5 and 1 hour after induction, and 0.5 hour after anesthesia were compared between first and second anesthesia. There were no significant differences in serum and urine F concentrations at the same point between first and second anesthesia. Two obese patients exhibited peak concentrations greater than 50 mumol.l-1 of F. Laboratory findings of renal function remained stable throughout 2 operations, whereas hepatic function deteriorated in the two obese patients after the first anesthesia, and resolved within 14 days after the second anesthesia. In conclusion, it is suggested that the second exposure to sevoflurane within 7 day interval does not alter the sevoflurane metabolism. However, obesity may contribute to a rise in serum inorganic fluoride after repeated sevoflurane anesthesia.
Epinephrine can potentially worsen the neurotoxic effects of local anesthetics when used for spinal or epidural anesthesia. The vasoconstrictive property of epinephrine reduces dural blood flow, which in turn reduces the clearance of local anesthetics from the subarachnoid space. This study examined the histological and neurofunctional effects of intrathecally administered lidocaine combined with epinephrine in rats.Sixty-two rats were divided into 9 treatment groups: 5% or 7.5% lidocaine in 10% glucose solution with or without 0.1 or 0.5 mg/mL epinephrine, or epinephrine alone at 0.1 or 0.5 mg/mL in 10% glucose, or 10% glucose alone. Hind-limb motor function was evaluated immediately after drug injection by walking behavior. Sensory function was assessed by the response to radiant heat stimulation at just before and 1 week after the injection. Seven days after the injection, L3 spinal cord with anterior and posterior roots, the dorsal ganglion, and cauda equina were harvested and examined histologically.Histological lesions were limited to the posterior root just at entry into the spinal cord in rats injected with 7.5% lidocaine, with and without epinephrine. No histological abnormalities were noted in other areas or other groups. There was no significant change in sensory threshold in all groups. Significantly, prolongation of gait recovery time was noted in 5% and 7.5% lidocaine with epinephrine groups compared with 5% or 7.5% lidocaine alone.Intrathecal epinephrine prolonged the action of intrathecal lidocaine but did not worsen lidocaine-induced histological damage and functional impairment.
Background: Fentanyl is intrathecally used as an adjuvant to bupivacaine in spinal anesthesia, as well as labor analgesia, and in day surgery. The aim of this study was to determine the separate neurotoxic effect of each drug using histological analysis. Methods: Rats (N = 39) received fentanyl at 0.12μl/g body weight (0.05, 0.5, and 1 mg/ml) or bupivacaine (5, 25, and 50 mg/ml) dissolved in saline via an intrathecal catheter. Saline was used as the control solution. Walking behavior and sensory threshold were used as neurofunctional tests. Seven days after the intrathecal injection, the L2 spinal cords, of each rat, with both anterior and posterior roots, including the dorsal ganglion and cauda equina, were examined histologically. Results: No histological abnormalities were observed in any of the rats treated with fentanyl (0.05, 0.5, or 1 mg/ml) or bupivacaine (5 or 25 mg/ml). However, axonal degeneration originating from the posterior root, extending to the posterior white matter, was observed in rats treated with 50-mg/ml bupivacaine. Significantly higher sensory thresholds were observed in rats with 1 mg/ml fentanyl, or 50-mg bupivacaine at 2 hours after the injection. The higher thresholds gradually disappeared in rats with fentanyl after 1 hour even at 1 mg/ml, but remained in rats with 50-mg/ml bupivacaine after 2 hours, and significantly decreased at 7 days after the injection. The rats could walk normally within 15 minutes, 1 hour before, and 1 hour after the injection of fentanyl (0.05, 0.5, and 1 mg/ml), respectively, and within 1, 2, and 4 hours of bupivacaine (5, 25, and 50 mg/ml), respectively. Transient apnea was only observed in 1 rat treated with 0.05-mg/ml fentanyl, while both transient apnea and muscle rigidity were observed in rats treated with 0.5- and 1-mg/ml fentanyl. No rats treated with bupivacaine (5, 25, or 50 mg/ml) showed both side effects. Conclusions: Our results indicated that intrathecal fentanyl does not cause any neurotoxic changes even at more than 40 times the clinical concentration (1 mg/ml), whereas bupivacaine causes nerve damage even when applied at 10 times the clinical concentration (50 mg/ml) in the spinal rat model. Side effects such as respiratory depression and muscle rigidity were seen in rats in the fentanyl group, even at 0.05 mg/ml. These results suggested that intrathecal fentanyl has strong side effects but low neurotoxicity because of the absence of morphological neurotoxicity even at high concentrations, whereas intrathecal bupivacaine induced sensory disturbance associated with axonal degeneration.
The purpose of this study is to determine if intrathecal 2% tetracaine (TC) causes histological changes by its neurotoxicity, and to examine the relationship between the lesions and neurological functions. Twenty-two rats received either 2% TC or 0% TC dissolved in 10% glucose, via an intrathecal catheter terminated at T 13 level. Neurological deficits were evaluated by rat's behavior and paw stimulation test (UCSF). Five days after drug administration, the L 1 spinal cord with the anterior and posterior roots and cauda equina were excised for light and electron microscopy. Four rats out of 8 in 2% TC group showed mild pathological changes induced by neurotoxicity mainly in the posterior roots and slightly in the posterior column. However, there were no significant differences in sensory and behavioral function between the rats who had received 2% TC with lesion and the others with no lesion. As many rootlets enter one segment of the spinal cord, mild and restricted lesions may be difficult to detect by sensory tests. These findings may explain the fact that the patients with transient neurologic symptoms (TNS) are normal by neurological tests.
