Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Isoflurane anesthesia and myocardial ischemia: comparative risk versus sufentanil anesthesia in patients undergoing coronary artery bypass graft surgery. The SPI (Study of Perioperative Ischemia) Research Group.
Whether isoflurane has the potential to produce coronary artery steal and associated myocardial ischemia is still controversial. Previous studies addressing this issue in humans did not purposefully control hemodynamics or use continuous measures of myocardial ischemia. The authors used transesophageal echocardiography (TEE) and continuous Holter electrocardiography (ECG) to study the relative risk of myocardial ischemia during isoflurane or sufentanil anesthesia under strict control of hemodynamics in 186 high-risk patients undergoing elective coronary artery bypass graft (CABG) surgery. ⋯ The duration and severity of electrocardiographic ischemic episodes were also similar in patients receiving either isoflurane or sufentanil. Four of the 62 patients (6%) who received isoflurane had an adverse cardiac outcome versus 15 of 124 patients (12%) who received sufentanil (P = 0.34). The authors' findings demonstrate that, when hemodynamics are controlled, the incidence of myocardial ischemia (TEE or ECG) during isoflurane and sufentanil anesthesia is similar.
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The recurrent laryngeal nerve was stimulated with surface electrodes to produce vocal cord adduction, and the response was measured as pressure changes in the inflatable cuff of a tracheal tube positioned between the vocal cords. To test the linearity of the system, a model of the larynx consisting of a syringe barrel was constructed, and weights were applied to two bands of tissue simulating the vocal cords. Tests on Mallinckrodt size-7.5 tubes showed that the pressure increase produced by a given force was independent of baseline pressure in the range 10-30 mmHg. ⋯ A surface electrode placed over the notch of the thyroid cartilage produced consistent adduction of the cords, measured as an increase of 8.9 +/- 5.1 mmHg (mean +/- standard deviation [SD]) in the cuff pressure. Neuromuscular blocking drugs produced train-of-four fade, and large doses abolished the response completely, ruling out direct muscle stimulation. It is concluded that this assembly can provide useful information on intrinsic laryngeal muscle function.
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Desflurane is a potent inhaled anesthetic associated with a dose-dependent depression of cortical electrical activity. Recently, it has been suggested that the burst suppression pattern seen in dogs given moderately high doses (2.0 MAC) of desflurane may spontaneously subside. This observation suggests the development of acute tolerance to at least some of the anesthetic effects of this drug. ⋯ Suppression was more complete at 1.7 MAC than at 1.5 MAC (98.24 +/- 1.75 vs. 90.80 +/- 3.05%, respectively, mean +/- standard deviation). The degree of burst suppression activity did not change over time at either 1.5 (P greater than 0.33) or 1.7 MAC desflurane (P greater than 0.41). There was no EEG evidence of tolerance to desflurane anesthesia in swine.
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Intravenous lidocaine has been shown to relieve acute postoperative pain and chronic neuropathic pain. It is not known whether analgesia produced by 2-10 micrograms/ml plasma concentrations of lidocaine is due to an effect on peripheral-pain-transducing nerves or to central nervous system effects. The current study examined effects of analgesic concentrations of lidocaine on injury-induced discharge of A-delta and C fibers, using the in vitro rabbit corneal nerve preparation. ⋯ The median effective concentration (ED50) (5.7 micrograms/ml) corresponds to clinically effective plasma concentrations for analgesia. Electrically evoked nerve conduction was not blocked until lidocaine concentrations were greater than 250 micrograms/ml. Thus, analgesia produced by lidocaine appears to result from suppression of tonic neural discharge in injured peripheral A-delta and C fiber nociceptors.
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Randomized Controlled Trial Multicenter Study Clinical Trial
The effects of the addition of sufentanil to 0.125% bupivacaine on the quality of analgesia during labor and on the incidence of instrumental deliveries.
In a double-blinded, randomized, prospective multi-center study of 695 women, we investigated whether epidural injection of sufentanil added to 0.125% bupivacaine with epinephrine (1:800,000) reduces the total amount of local anesthetic required, resulting in less motor blockade and reduced incidence of instrumental deliveries, and improves the quality of analgesia provided by this low concentration of local anesthetic without jeopardizing the safety of the baby. In addition, other potential benefits of sufentanil (such as decrease in the incidence of shivering) and side effects were examined. ⋯ The only side effect that occurred more frequently after sufentanil was pruritus. We conclude that epidural injection of 10-30 micrograms sufentanil added to 0.125% bupivacaine with epinephrine (1:800,000) improved the quality of analgesia during labor and reduced the incidence of instrumental deliveries without jeopardizing the safety of the baby.