Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2001
Case ReportsThe use of a "reverse" axis (axillary-interscalene) block in a patient presenting with fractures of the left shoulder and elbow.
A patient presented for surgery to repair a fractured left shoulder and elbow and requested regional anesthesia. Most upper extremity operations require a single brachial plexus nerve block. The position of the two fractures however required the use of two separate approaches, an interscalene and an axillary approach.
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Anesthesia and analgesia · Dec 2001
Case ReportsGeneralized tonic-clonic activity after remifentanil administration.
This is the first report of seizure-like activity in an adult who received remifentanil. This report confirms that opioid administration can be associated with generalized tonic-clonic seizure-like activity. It is suggested that this reaction could be referred to as the "opioid-seizure syndrome."
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Anesthesia and analgesia · Dec 2001
How does the plethysmogram derived from the pulse oximeter relate to arterial blood pressure in coronary artery bypass graft patients?
Twenty patients scheduled for coronary artery bypass grafting had their ear and finger oximeter and radial artery blood pressure (Bp(meas)) waveforms collected. The ear and finger pulse oximeter waveforms were analyzed to extract beat-to-beat amplitude and area and width measurements. The Bp(meas) waveforms were analyzed to measured systolic blood pressure (BP), mean BP, and pulse pressure. The correlation coefficient was determined between the derived waveforms from the pulse oximeter and Bp(meas) for the first 10 patients. The ear pulse oximeter width (Width(Ear)) had the best correlation (r = 0.8). Linear regression was done between Width(Ear) and Bp(meas) based on slope (b) and intercept (a) values, BP was calculated (Bp(calc)) in the next 10 patients as: [equation: see text] where i = systolic BP, mean BP, and pulse pressure. The initial bias was too large to be clinically useful. To improve clinical applicability a period of calibration was introduced in which the first 50 readings of Width(Ear) and Bp(meas) for each patient were used to calculate the intercept. After calibration the systolic BP, mean BP and pulse pressure bias values were -2.6, -1.88 and -1.28 mm Hg, and the precision values were 15.9 10.09, and 9.94 mm Hg, respectively. The present attempt to develop a clinically useful method of noninvasive BP measuring was partly successful with the requirement of a calibration period. ⋯ Statistical comparison was made between measured blood pressure (BP) from arterial line and calculated BP derived from ear pulse oximeter waveform in 10 patients undergoing coronary artery bypass graft surgery. Using 62,077 paired readings, the mean difference for systolic BP, mean BP, and pulse pressure between the 2 methods was -2.6, -1.88, and -1.28 mm Hg, respectively.
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Anesthesia and analgesia · Dec 2001
Thoracic, but not lumbar, epidural anesthesia improves cardiopulmonary function in ovine pulmonary embolism.
We hypothesized that sympathetic stimulation is the main mechanism contributing to hemodynamic failure in pulmonary embolism. We investigated the effects of epidural anesthesia-induced sympathetic blockade, restricted to thoracic and lumbar levels, during pulmonary embolism. Two experiments were performed in chronically instrumented ewes. In the first experiment, six sheep received 6 mL bupivacaine 0.175% (Thoracic Epidural Anesthesia [TEA] group), and six sheep received 6 mL saline 0.9% (TEA-Control group), respectively, via an epidural catheter (T3 level). In the second experiment, six sheep received 2.8 mL bupivacaine 0.375% (Lumbar Epidural Anesthesia [LEA] group), and six sheep received 2.8 mL saline 0.9% (LEA-Control group) epidurally (L4 level). Embolization was performed by IV injection of autologous blood clots (Experiment 1, 0.75 mL/kg; Experiment 2, 0.625 mL/kg). TEA was associated with significantly slower heart rates, decreased mean pulmonary artery pressures and central venous pressures, and significantly higher stroke volume index and oxygenation in comparison with the TEA-Control group. By contrast, LEA was associated with significantly faster heart rates and increased central venous pressures and with a significantly lower stroke volume index in comparison with the LEA-Control group. TEA significantly reduced, and LEA significantly increased, hemodynamic deterioration, suggesting beneficial effects of TEA on cardiopulmonary function during pulmonary thromboembolism. ⋯ Thoracic (but not lumbar) epidural anesthesia was associated with beneficial cardiopulmonary effects during experimental pulmonary thromboembolism in sheep.
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Anesthesia and analgesia · Dec 2001
The involvement of the mu-opioid receptor in ketamine-induced respiratory depression and antinociception.
N-methyl-D-aspartate receptor antagonism probably accounts for most of ketamine's anesthetic effects; its analgesic properties are mediated partly via N-methyl-D-aspartate and partly via opioid receptors. We assessed the involvement of the mu-opioid receptor in S(+) ketamine-induced respiratory depression and antinociception by performing dose-response curves in exon 2 mu-opioid receptor knockout mice (MOR(-/-)) and their wild-type littermates (WT). The ventilatory response to increases in inspired CO(2) was measured with whole body plethysmography. Two antinociceptive assays were used: the tail-immersion test and the hotplate test. S(+) ketamine (0, 10, 100, and 200 mg/kg intraperitoneally) caused a dose-dependent respiratory depression in both genotypes, with greater depression observed in WT relative to MOR(-/-) mice. At 200 mg/kg, S(+) ketamine reduced the slope of the hypercapnic ventilatory response by 93% +/- 15% and 49% +/- 6% in WT and MOR(-/-) mice, respectively (P < 0.001). In both genotypes, S(+) ketamine produced a dose-dependent increase in latencies in the hotplate test, with latencies in MOR(-/-) mice smaller compared with those in WT animals (P < 0.05). In contrast to WT mice, MOR(-/-) mice displayed no ketamine-induced antinociception in the tail-immersion test. These results indicate that at supraspinal sites S(+) ketamine interacts with the mu-opioid system. This interaction contributes significantly to S(+) ketamine-induced respiratory depression and supraspinal antinociception. ⋯ The involvement of the mu-opioid receptor system in S(+) ketamine-induced respiratory depression and spinal and supraspinal analgesia was demonstrated by performing experiments in mice lacking the mu-opioid receptor and in mice with intact mu-opioid receptors.