Anesthesia and analgesia
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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.
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Anesthesia and analgesia · Dec 1990
Comparative StudyTransesophageal Doppler ultrasonography: evidence for improved cardiac output monitoring.
Cardiac output monitoring by transesophageal Doppler ultrasound has not gained wide clinical acceptance. A recently developed transesophageal Doppler device, Accucom 2, features technological advances aimed to reduce the error of this approach to the monitoring of cardiac output. ⋯ Results using Accucom 2 were highly correlated with the results obtained with thermodilution (R = 0.91) and provided significantly greater accuracy in comparison with a previously developed Doppler cardiac output monitor, Accucom 1. Technological advances in transesophageal Doppler ultrasound hold promise for clinically useful noninvasive monitoring of cardiac output.
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Anesthesia and analgesia · Dec 1990
Comparative StudyElimination kinetics of sevoflurane and halothane from blood, brain, and adipose tissue in the rat.
Using the rat as an animal model, the elimination kinetics of sevoflurane and halothane from brain, blood, and adipose tissue were compared. Elimination of sevoflurane and halothane from blood and brain was biexponential. ⋯ However, the slower beta-elimination rates from brain and blood, as well as the elimination rates from adipose tissue, were similar for both volatile anesthetics. Thus, the potential for residual postoperative impairment from subanesthetic tissue concentrations of halothane and sevoflurane may be similar even though sevoflurane is initially eliminated more rapidly from blood and brain.