Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1990
Randomized Controlled Trial Clinical TrialNitrous oxide and epinephrine-induced arrhythmias.
We asked whether the sympathomimetic effect of nitrous oxide (N2O) predisposed patients receiving N2O to arrhythmias in response to epinephrine administration. We also asked whether aging contributed to the development of arrhythmias, with or without N2O. One hundred patients having transsphenoidal hypophysectomy were randomly assigned to receive anesthesia including (n = 49) or excluding (n = 51) N2O. ⋯ Both anesthetic groups had a high incidence of postoperative changes in T-wave morphology (46.9% in the N2O group vs 50.9% in the group not given N2O). Aging alone did not affect the incidence of ventricular ectopic beats, isorhythmic AV dissociation, or changes in electrocardiographic morphology, but correlated with the development of ventricular ectopy during N2O anesthesia. We conclude that the use of N2O correlated with a higher incidence of isorhythmic AV dissociation in response to injection of epinephrine with lidocaine.
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Anesthesia and analgesia · Dec 1990
Randomized Controlled Trial Clinical TrialNo finding of increased myocardial ischemia during or after carotid endarterectomy under anesthesia with nitrous oxide.
Nitrous oxide (N2O) has been implicated as a cause of myocardial ischemia. We investigated whether substitution of N2O for a portion of the anesthesia supplied by isoflurane increased myocardial ischemia in patients at risk for such ischemia. Seventy patients having carotid endarterectomies (63 patients) or other carotid surgery (seven patients) were prospectively, randomly assigned to an anesthetic regimen that included or excluded N2O. ⋯ By transesophageal echocardiographic or electrocardiographic criteria, 44% of patients given oxygen but only 21% of those given N2O had myocardial ischemia intraoperatively (P = 0.065). Similarly, myocardial infarction, identified by changes in creatine kinase isoenzymes, occurred in only one patient given N2O but in three given oxygen (not significantly different). Thus we found no trend indicating a greater incidence of myocardial ischemia or infarction associated with the use of N2O.
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Anesthesia and analgesia · Dec 1990
Randomized Controlled Trial Clinical TrialClinical pharmacology of nitrous oxide: an argument for its continued use.
We tested the hypothesis that the administration of nitrous oxide (N2O) causes major (e.g., myocardial infarction, neuronal injury, hypoxemia, infection, death) or minor (e.g., nausea, vomiting, headache, earache) untoward effects in patients requiring anesthesia for 1.5-4 h. Given the higher morbidity and mortality associated with aging, we also tested whether aging increased any untoward effect of N2O. Finally, we investigated whether the substitution of N2O for a fraction of the anesthesia supplied by isoflurane altered the latter's pharmacologic effects. ⋯ The addition of N2O administration decreased the isoflurane requirement for clinical anesthesia but did not alter most of the clinical variables measured in practice, including blood pressure, heart rate, rate of recovery from anesthesia, development of postoperative pain, patient satisfaction with anesthesia, or duration of anesthesia or of hospitalization. Patients given N2O were no more likely to dream during anesthesia, remember events during anesthesia, or be frightened by those events. Our results support the continued use of N2O to anesthetize patients for elective surgery.
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Anesthesia and analgesia · Dec 1990
Randomized Controlled Trial Clinical TrialLidocaine local anesthesia for arthroscopic knee surgery.
Forty-five patients were evaluated during knee arthroscopy performed using local anesthesia produced by lidocaine with epinephrine to determine the dose-response relationship for operative analgesia. Serum lidocaine concentrations were also measured. Patients were randomized prospectively to receive 20 mL of 0.5%, 1.0%, or 1.5% lidocaine with epinephrine intraarticularly. ⋯ Serum lidocaine concentrations before and 15, 30, 60, and 120 min after instillation of lidocaine were highest in the 1.5% lidocaine group with a peak concentration of 278 ng/mL. No patient had symptoms of lidocaine toxicity. We recommend that lidocaine concentrations of 1.0% or 1.5% be used when 20 mL is instilled intraarticularly for knee arthroscopy based on patient comfort and absence of lidocaine toxicity.
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Nitrous oxide can cause hematologic abnormalities, including death, if it is administered for several days. However, the adverse hematologic effects of its use for surgical anesthesia are unclear. Accordingly, we have studied the hematologic responses of patients undergoing procedures involving hematologic stress or prolonged anesthesia with and without nitrous oxide. ⋯ Nitrous oxide did not affect the production of red blood cells or platelets. Nitrous oxide treatment was associated with an increase in postoperative leukocyte levels that was modestly but significantly smaller than that found in patients not given nitrous oxide. There was no evidence that this small decrease in maximal leukocytosis adversely affected clinical outcome.