Anesthesiology
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Randomized Controlled Trial Clinical Trial
Potentiation of succinylcholine phase II block with isoflurane.
To determine the effect of isoflurane upon phase II block 20 patients were given succinylcholine by infusion at a rate which maintained the twitch tension of the adductor pollicis muscle at 10% of control for 2 to 4 h. The patients were assigned randomly to either nitrous-oxide-isoflurane (0.75-1.5% inspired) or nitrous-oxide-fentanyl for maintenance of anesthesia, and neuromuscular activity was monitored using train-of-four stimulation. ⋯ This decrease was related to the extent of phase II block present. It is concluded that isoflurane potentiates succinylcholine phase II block although the mechanisms involved are not necessarily the same as in the potentiation of nondepolarizing neuromuscular blocking drugs.
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Randomized Controlled Trial Clinical Trial
The role of epidural morphine in the postcesarean patient: efficacy and effects on bonding.
This study was designed to determine in postcesarean patients whether in addition to superior analgesic effects, epidural morphine administration results in secondary benefits in maternal well-being and maternal-infant interaction. Following elective cesarean section with bupivacaine epidural anesthesia, 40 healthy mothers received 5 mg preservative-free morphine sulfate in 10 ml of saline, either by the epidural (Group 1, n = 20) or the intravenous (Group 2, n = 20) route, in a randomized, double-blind fashion. Each received a simultaneous injection of saline by the alternate route. ⋯ Itching occurred in 58% of Group 1 patients and only 16% of Group 2 patients (P less than 0.01); the incidences of nausea, vomiting, and urinary retention were not statistically different between the groups. No respiratory depression was observed. Benefits of epidural morphine in this patient population appear limited to the provision of improved analgesia and earlier mobility.
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The present study examined the influence of spinally administered fentanyl on the spontaneous and noxiously evoked activity of wide dynamic range (WDR) neurons in the dorsal horn of decerebrate, spinal cord-transected cats. This work was performed in order to evaluate the dose-response relationship, time course, and naloxone reversibility of fentanyl suppression of neurons that are involved with the transmission of information about pain. Extracellular single neuron recordings were obtained from 18 WDR neurons in the lumbar enlargement. ⋯ Such results support the concept that fentanyl is acting through a specific drug-receptor interaction. The onset of neuronal suppression occurred more rapidly, and the duration of the suppression was longer following fentanyl than that seen following spinal morphine. The onset and duration of this suppression correlates well with human clinical data, providing further evidence that alterations of WDR neuronal activity may be important in the production of spinal opioid analgesia.
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Comparative Study
Comparison of isoflurane and halothane safety margins in rats.
In rat experiments, the dose-effect curves for three different end points of anesthesia [loss of righting reflex (RR), prevention of movement (PM), and heart rate response (HR) to noxious stimuli] and for the lethal effect (LE) due to cardiovascular depression were determined with isoflurane and halothane. The obtained data were used to calculate LD50/ED50 ratios and standard safety margins (SSM) for assessment of each agent's safety. It was found that isoflurane provides an equal degree of separation between dose-effect curves for different end points of anesthesia as halothane does. ⋯ The margin between the highest of anesthetic doses--the loss of HR response--and the lethal dose for isoflurane was twice that for halothane (LD50/HR ED50 4.3 vs. 2.2, P less than 0.01). The standard safety margin for the loss of HR response was also greater with isoflurane (142 vs. 43, P less than 0.05). These results agreed that isoflurane may provide greater cardiovascular safety for anesthesia than halothane does.