Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1996
Randomized Controlled Trial Clinical TrialReducing pain during propofol injection: the role of the solvent.
We hypothesized that the concentration of propofol in the aqueous phase may be the most important variable responsible for the pain experienced during injection of the drug. The concentration of propofol in the aqueous phase (18.57 micrograms/mL) can be decreased by increasing the fat content of the solvent. To test this hypothesis, 36 patients were randomly allocated to one of three groups, each receiving a different formulation of propofol. ⋯ Our results suggest that a smaller concentration of propofol in the aqueous phase of the emulsion reduces pain on injection. With the addition of more lipid (10 mL), a higher percentage of propofol is absorbed by fat particles. If solvents that permit a smaller concentration of the drug in the aqueous phase of oil-in-water emulsions were used for propofol and other drugs that cause pain on injection, pain would be reduced and patient satisfaction may be increased.
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Anesthesia and analgesia · Mar 1996
The response to varying concentrations of inhaled nitric oxide in patients with acute respiratory distress syndrome.
We investigated the response to varying concentrations of inhaled nitric oxide (NO) in 18 patients with acute respiratory distress syndrome (ARDS). The study was divided into two parts. In Part 1, 5-40 ppm of inhaled NO was evaluated in 10 patients with ARDS. ⋯ While the maximum hemodynamic and oxygenation responses to inhaled NO are achieved at approximately 1 ppm, it appears that the maximum hemodynamic response is observed at lower concentrations (0.1 ppm) of inhaled NO than the improvement in oxygenation (1-10 ppm). Higher concentrations of NO do not produce any further change in these variables. It appears that the baseline PVRI may be the best marker predicting a beneficial response to NO.
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Anesthesia and analgesia · Mar 1996
Comparative StudyIntraoperative myogenic motor evoked potentials induced by direct electrical stimulation of the exposed motor cortex under isoflurane and sevoflurane.
We monitored myogenic motor evoked potentials (MEPS) during intracranial surgery in 21 patients anesthetized with nitrous oxide in oxygen, fentanyl, and 0.75-1.5 minimum alveolar anesthetic concentration (MAC) isoflurane (n = 11) or sevoflurane (n = 10). The exposed motor cortex was stimulated with a single or train-of-five rectangular pulses at a high frequency (500 Hz), while the compound muscle action potentials (CMAPS) were recorded from the abductor pollicis brevis muscle. Neuromuscular block was monitored by recording the CMAPs from the abductor pollicis brevis muscle in response to electrical stimulation of the median nerve at the wrist (M-response). ⋯ In the remaining patient, MEP amplitudes were attenuated to approximately 10% of the baseline value and recovered after cessation of surgical manipulation. In the two patients in whom MEPs disappeared, motor paresis developed postoperatively. We conclude that 1) intraoperative myogenic MEP monitoring is feasible during isoflurane or sevoflurane anesthesia if stimulation is performed with a short train of rectangular pulses, and 2) that electromyographic monitoring of neuromuscular block is useful to assess intraoperative MEP changes under partial neuromuscular block.
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Anesthesia and analgesia · Mar 1996
Comparative StudyOndansetron blocks nifedipine-induced analgesia in rats.
The serotonergic system is involved in pain transmission and the 5-hydroxytryptamine (5-HT3) receptor subtype mediates some of these effects at the spinal level. Therefore, we explored the effects of the serotonergic system on nifedipine-induced analgesia by using the 5-HT3 receptor antagonist ondansetron. Male Sprague-Dawley rats were pretreated with ondansetron (1 mg/ kg intraperitoneally) or normal saline. ⋯ Rats treated with nifedipine alone had an increase in tail-flick latency of 122%, as measured by the area under the curve, compared to rats treated with DMSO alone. Pretreatment with ondansetron, however completely blocked the analgesic effect of nifedipine, with tail-flick latency remaining at baseline throughout the measurement period. These results indicate that the 5-HT3 receptor plays an important role in the analgesic response to nifedipine and that medications that block this receptor may decrease the analgesic effectiveness of this type of therapy.
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Anesthesia and analgesia · Mar 1996
Randomized Controlled Trial Comparative Study Clinical TrialNaloxone versus nalbuphine infusion for prophylaxis of epidural morphine-induced pruritus.
This randomized, double-blind study compared the efficacy of two mu-receptor antagonists, naloxone and nalbuphine, in the prophylactic management of pruritus in postcesarean section patients receiving epidural morphine. Dosages of study drugs were individualized by the use of a patient self-administration (PSA) device. All 51 patients were healthy women who received a uniform epidural anesthetic and epidural morphine (5 mg). ⋯ The potency ratio for naloxone:nalbuphine for antagonism of the pruritic effects of epidural morphine was approximately 40:1. Intervention to treat either unrelieved pruritus or pain, respectively, was necessary in the following numbers of patients: Group A, 0/1; Group B, 1/1; Group C, 2/2. Prophylactic infusions offer the potential for labor cost savings by minimizing the need for episodic therapeutic interventions to treat pruritus.