Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1998
Randomized Controlled Trial Clinical TrialDroperidol and the side effects of epidural morphine after cesarean section.
Epidural morphine produces analgesia with a high incidence of side effects that include pruritus, nausea, and vomiting. This study investigated whether epidural or i.v. droperidol could alleviate these symptoms. In a prospective, double-blind, randomized, controlled trial, 97 pregnant women undergoing cesarean section were randomly assigned to three groups. All received standard continuous epidural anesthesia. After delivery, each received 5 mg of epidural morphine with either no droperidol injection, 2.5 mg of epidural droperidol, or 2.5 mg of i.v. droperidol. The incidence, onset, duration, and severity of pruritus; the onset and severity of pain; and satisfaction were similar for each group, but the incidence and severity of nausea and vomiting was lower in the group that received i.v. droperidol (P < 0.01). Sedation was minimal throughout the study. Thus, epidural droperidol failed to alleviate the side effects caused by epidural morphine, but i.v.droperidol reduced both the incidence and severity of nausea and vomiting. These results suggest that droperidol acts systemically to counter the effects of epidural morphine but that it is not entirely effective. ⋯ A single dose of epidural morphine provides long-lasting pain relief for women who have undergone cesarean section, but it has some troublesome side effects (itching, nausea, vomiting). We performed a prospective, randomized, controlled trial in 97 such women to study whether droperidol could reduce these side effects. We found that i.v. droperidol reduced nausea and vomiting but did not prevent itching, and that epidural droperidol failed to prevent all side effects.
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Anesthesia and analgesia · Mar 1998
Clinical TrialTreatment of intractable pain with topical large-dose capsaicin: preliminary report.
Complex regional pain syndromes (CRPS) and neuropathic pain are often poorly controlled by conventional pharmacologic interventions. We administered 8-methyl-N-vanillyl-noneamide (capsaicin) at doses of 5%-10% to individuals with such disorders in this trial. Previous limitations to trials with larger-dose, topical concentrations of capsaicin included intense burning sensations experienced after application. To enable patients to tolerate the high concentrations, we first performed regional anesthesia. All patients reported at least some relief. Of 10 patients, 9 obtained substantial analgesia that lasted 1-18 wk. At Week 1 after therapy, the mean verbal analog scale (VAS) scores decreased from 8.0 to 3.0. At Week 4 after therapy, mean VAS score was 4.5. Analgesia lasted from < 1 wk (1 patient) to more than 50 wk (1 patient). Patients received one to eight treatments. With one exception, patients receiving more than one treatment obtained additional relief with subsequent treatment. Pain responsive to opioids was the only side effect of treatment. Large-dose capsaicin administered with regional anesthesia may effectively minimize refractory CRPS and neuropathic pain. A double-blind, placebo-controlled study in patients with bilateral peripheral neuropathy using epidural anesthesia with and without large-dose topical capsaicin is in progress. ⋯ Sensory neuropathies are associated with many diseases. Pain from these disorders can produce greater disability than the primary disease processes themselves. Currently available therapies are limited. However, the intermittent application of large-dose topical capsaicin may provide significant pain relief, decrease chronic analgesic dependence, and decrease aggregate health care expenditures.
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Anesthesia and analgesia · Mar 1998
The infusion rate of mivacurium and its spontaneous neuromuscular recovery in magnesium-treated parturients.
Magnesium (Mg) enhances the activity of nondepolarizing neuromuscular blocking drugs. However, no interaction between mivacurium and magnesium has been described. Therefore, we sought to determine the effect of the influence of Mg on the infusion rate of mivacurium and its spontaneous recovery. We studied 24 parturients who had undergone cesarean section under general anesthesia. Those who had been given MgSO4 for the treatment of preeclampsia were assigned to the Mg group (n = 12), and the other normal parturients were assigned to the NonMg group (n = 12). In both groups, the train-of-four (TOF) response to stimuli of the ulnar nerve was measured at intervals of 15 s. Anesthesia was induced with thiopental and succinylcholine. In both groups, a bolus dose of mivacurium 0.06 mg/kg was administered when the first twitch of TOF (T1) reached 100% after the succinylcholine injection. When the electromyographic response after mivacurium had recovered to approximately 5%-10% of the baseline, a continuous infusion of mivacurium was given to maintain 93%-97% neuromuscular blockade. The plasma concentration of Mg in blood of the Mg group was 4.0 1.0 mEq/L, higher than that (1.4 mEq/L) of the NonMg group (P < 0.01). The infusion rates of mivacurium of Mg and NonMg groups were 1.6 and 5.4 mEq x kg(-1) x min(-1), respectively. In addition, the recovery indexes of the Mg and NonMg groups were 12.9 and 4.3 min, respectively. We conclude that a smaller dose of mivacurium should be infused to patients receiving Mg. ⋯ Magnesium, used as a standard therapy for severe toxemia, may act to enhance muscle relaxants such as mivacurium, a short-acting drug used in general anesthesia. Among women undergoing a cesarean section who were given a magnesium pretreatment, the infusion rate of mivacurium required to obtain relaxation was lower than that among women who did not receive pretreatment.
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Anesthesia and analgesia · Mar 1998
Epithelial dependence of the bronchodilatory effect of sevoflurane and desflurane in rat distal bronchi.
The bronchial epithelium releases substances that enhance bronchodilation in response to certain bronchodilators. We examined the hypothesis that the bronchodilatory effect of desflurane and sevoflurane depends on the epithelium in rat distal bronchial segments. Wistar rat subsegmental bronchial segments (diameter approximately 100 microm) were dissected. After preconstriction with 5-hydroxytryptamine, each segment was exposed to increasing concentrations of desflurane 0%-12% or sevoflurane 0%-4.8% under four conditions: after epithelial rubbing, after pretreatment with the nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine (L-NNA), after pretreatment with the cyclooxygenase inhibitor indomethacin, or with no preintervention (control). Changes in bronchial diameter were monitored using an in vitro video detection system. Both desflurane and sevoflurane produced concentration-dependent bronchodilation (P < 0.001 for either anesthetic; 54% +/- 8% [mean +/- SD] dilation for 12% desflurane and 48% +/- 14% dilation for 4.8% sevoflurane). For both anesthetics, bronchodilation was significantly attenuated by epithelial rubbing (15% +/- 4% dilation for 12% desflurane and 13% +/- 10% dilation for 4.8% sevoflurane; P < 0.001 each), by pretreatment with indomethacin (12% +/- 3% dilation for 12% desflurane and 9% +/- 5% dilation for 4.8% sevoflurane; P < 0.001 each), and by L-NNA (24% +/- 8% dilation for 12% desflurane, P < 0.001; and 17% +/- 10% dilation for 4.8% sevoflurane, P < 0.01). Desflurane- and sevoflurane-mediated bronchodilation depends at least partially on the epithelium, and may involve both a prostanoid and NO in rat distal bronchi. ⋯ Bronchodilation by the volatile anesthetics desflurane and sevoflurane is at least partially epithelium-dependent and may be attenuated in diseases affecting the epithelium, such as asthma.
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Anesthesia and analgesia · Mar 1998
Mild hypothermia can attenuate nitroglycerin-induced vasodilation of pial arterioles in the cat.
The purpose of the present study was to investigate the effect of mild hypothermia on nitroglycerin-induced vasodilation of cerebral vessels. The cranial window technique, combined with microscopic video recording, was used in an experiment involving 26 cats anesthetized with isoflurane. Animals were randomly assigned to either a normothermic or a mildly hypothermic group (33 degrees C). We administered three different concentrations of nitroglycerin (10[-6], 10[-5], 10[-4] M) under the window and measured the diameter of small (< 100 microm) and large (100-200 microm) pial arterioles. In the normothermic group (n = 13), nitroglycerin produced a significant dilation of both small and large arterioles in a dose-dependent manner. In the hypothermic group (n = 13), a significant dilation of arterioles was observed only after topical application of nitroglycerin at a concentration of 10(-4) M. The percent increase in diameter of small and large arterioles was less in the hypothermic group than the normothermic group. Our in vivo study demonstrates that topically applied nitroglycerin produces a dose-dependent dilation of pial arterioles in normothermic cats anesthetized with isoflurane, but the reduction of temperature to 33 degrees C significantly attenuates nitroglycerin-induced vasodilation of pial arterioles. ⋯ Although nitroglycerin may be used in hypothermic patients, the effect of mild hypothermia on nitroglycerin-induced vasodilation of cerebral vessels is unknown. In this study, we investigated the effects of nitroglycerin on pial arteriolar diameter in normothermic and hyperthermic cats. Hypothermia was found to attenuate nitroglycerin-induced vasodilation.