Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1991
Case ReportsCauda equina syndrome after continuous spinal anesthesia.
Four cases of cauda equina syndrome occurring after continuous spinal anesthesia are reported. In all four cases, there was evidence of a focal sensory block and, to achieve adequate analgesia, a dose of local anesthetic was given that was greater than that usually administered with a single-injection technique. We postulate that the combination of maldistribution and a relatively high dose of local anesthetic resulted in neurotoxic injury. ⋯ Use of a lower concentration and a "ceiling" or maximum dose of local anesthetic to establish the block should be considered. If maldistribution of local anesthetic is suspected (as indicated by a focal sensory block), the use of maneuvers to increase the spread of local anesthetic is recommended. If such maneuvers prove unsuccessful, the technique should be abandoned.
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Anesthesia and analgesia · Mar 1991
Randomized Controlled Trial Clinical TrialPatient-controlled sedation during epidural anesthesia.
The purpose of this study was to evaluate the feasibility and advantages or disadvantages, if any, of patient-controlled sedation compared with sedation administered by the anesthesiologist during surgical epidural anesthesia. Forty patients were divided at random into two groups with 20 patients in each group. Patients in group 1 received 0.5-1.0 mg intravenous midazolam and 25-50 micrograms intravenous fentanyl in increments administered by the anesthesiologist to achieve intraoperative sedation; patients in group 2 self-administered a mixture of midazolam (0.5 mg) and fentanyl (25 micrograms) in increments using an Abbott Lifecare PCA infuser to achieve sedation. ⋯ This could have been due to a positive psychological effect produced by allowing patient to feel that they have some control over their situation. The findings of this study indicate that patient-controlled sedation using a combination of midazolam and fentanyl is a safe and effective technique that provides intraoperative sedation ranked better by patients than that provided by anesthesiologists using the same drugs. More studies are, however, needed to determine the best choice of drug(s), the doses, the lock-out intervals, and the possible use of continuous infusion with patient-controlled sedation.
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Anesthesia and analgesia · Mar 1991
Randomized Controlled Trial Clinical TrialEffects of succinylcholine on the pharmacodynamics of pipecuronium and pancuronium.
To study the effects of succinylcholine on subsequent pharmacodynamics of nondepolarizing muscle relaxants, a comparative pharmacodynamic study was carried out in patients having balanced anesthesia (thiopental, fentanyl, nitrous oxide/oxygen) in whom equipotent doses of pipecuronium (80 micrograms/kg) and pancuronium (100 micrograms/kg) were given with or without prior administration of succinylcholine (1 mg/kg). Fifty-two patients were randomly assigned to one of the following four groups: 1, pancuronium (100 micrograms/kg); 2, pipecuronium (80 micrograms/kg); 3, succinylcholine (1 mg/kg) plus pancuronium (100 micrograms/kg); and 4, succinylcholine (1 mg/kg) plus pipecuronium (80 micrograms/kg). In groups 3 and 4, the nondepolarizing relaxant was given after succinylcholine when the twitch height recovered to 75% of its control value. ⋯ Mean onset times for pancuronium (group 1) and pipecuronium (group 2) given without succinylcholine were (mean +/- SEM) 2.5 +/- 0.3 and 2.8 +/- 0.2 min, respectively. Mean onset times (times to maximum twitch depression) of the two drugs given after succinylcholine (groups 3 and 4) were significantly shorter (1.4 +/- 0.4 and 1.6 +/- 0.1 min, respectively). Clinical durations (i.e., until 25% twitch recovery of pancuronium and pipecuronium) were not significantly different among the four groups, varying from 81.1 +/- 5.4 (group 4) to 107.0 +/- 17.0 (group 2) min.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Mar 1991
Comparative StudyComparison of kinetics of sevoflurane and isoflurane in humans.
The low solubility of sevoflurane in blood suggests that this agent should enter and leave the body more rapidly than isoflurane. However, the closeness of sevoflurane and isoflurane tissue/blood partition coefficients suggests that the rates of equilibration with and elimination from tissues should be similar. We tested both predictions, comparing sevoflurane with isoflurane and nitrous oxide in seven volunteers. ⋯ FA/FA0 (FA0 = the last FA during administration) values after 5 min of elimination were as follows: sevoflurane, 0.157 +/- 0.020; isoflurane, 0.223 +/- 0.024. Recovery (volume of anesthetic recovered during elimination/volume taken up) of sevoflurane (101% +/- 7%) equaled recovery of isoflurane (101% +/- 6%). Time constants for a five-compartment mammillary model for sevoflurane were smaller than those for isoflurane for the lungs but were not different from isoflurane for the other compartments.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Mar 1991
Comparative StudyLow-dose bupivacaine does not improve postoperative epidural fentanyl analgesia in orthopedic patients.
Epidural infusions of 10 micrograms/mL fentanyl combined with low-dose bupivacaine (0.1%) were compared with epidural infusions of fentanyl alone for postoperative analgesia after total knee joint replacement. There were no detectable differences between the two groups in analgesia (visual analogue scale ranging between 15 and 40 mm), infusion rates (which averaged 7-9 mL/h), or serum fentanyl levels (which reached 1-2 ng/mL). ⋯ Of the patients receiving fentanyl and low-dose bupivacaine, one developed a transient unilateral motor and sensory loss, and one developed significant hypotension and respiratory depression. The addition of low-dose bupivacaine does not improve epidural fentanyl infusion analgesia after knee surgery and may increase morbidity.