Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2006
Randomized Controlled Trial Comparative StudyContinuous positive airway pressure breathing increases the spread of sensory blockade after low-thoracic epidural injection of lidocaine.
Factors affecting the distribution of sensory blockade after epidural injection of local anesthetics remain incompletely clarified. To evaluate if increasing intrathoracic pressure affects the spread of thoracic epidural anesthesia, we randomized 20 patients who received an epidural catheter at the T7-8 or T8-9 intervertebral space into 2 groups. The control group (n = 10) received an epidural test dose of 4 mL lidocaine 2% during spontaneous breathing at ambient pressure. ⋯ The total number of segments blocked was 7 (median, interquartile range 2.25) in the control group and 11 (interquartile range 3.5) in the continuous positive airway pressure group (P = 0.004). The number of segments blocked caudad to the injection site was 3 (median, interquartile range 3.5) in the control group and 6 (interquartile range 2.25) in the continuous positive airway pressure group (P = 0.005). We conclude that continuous positive airway pressure increases the spread of sensory blockade in thoracic epidural anesthesia, primarily by a more caudad extension of sensory blockade.
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Anesthesia and analgesia · Jan 2006
Comparative StudyThe effects of sevoflurane and propofol on QT interval and heterologously expressed human ether-a-go-go related gene currents in Xenopus oocytes.
Sevoflurane can induce prolongation of the cardiac QT interval by inhibiting the repolarization phase of the action potential. This may occur as a result of inhibition of the human ether-a-go-go related gene (HERG) channel. To clarify the mechanisms of anesthetics on HERG channels, we monitored the electrocardiogram and measured QT intervals in the guinea pig in the presence of sevoflurane and propofol. ⋯ The time constant of the converging current was decreased in the presence of sevoflurane, but the inactivation and activation curves were not shifted. Propofol did not affect these currents within the clinically relevant concentration. In conclusion, compared with steady-state currents, sevoflurane was more potent in inhibiting the outward tail currents, suggesting that sevoflurane may modulate the HERG channel kinetics in its inactivated state.
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Anesthesia and analgesia · Jan 2006
Randomized Controlled Trial Comparative StudyThe analgesic effect of tramadol after intravenous injection in healthy volunteers in relation to CYP2D6.
Tramadol analgesia results from a monoaminergic effect by tramadol itself and an opioid effect of its metabolite (+)-M1 formed by O-demethylation of tramadol by CYP2D6. In this study we sought to determine the impact of (+)-M1 on the analgesic effect of tramadol evaluated by experimental pain models. The effect of an IV injection of 100 mg tramadol on experimental pain was studied 15-90 min after dosing in volunteers, 10 extensive metabolizers with CYP2D6 and 10 poor metabolizers without CYP2D6 in 2 placebo-controlled trials. ⋯ In extensive metabolizers, tramadol reduced discomfort experienced during the cold pressor test (P = 0.002). In poor metabolizers, the pain tolerance thresholds to sural nerve stimulation were increased (P = 0.04). (+)-M1 could be detected in the serum samples from all extensive metabolizers except one, but (+)-M1 was below the limit of determination in all poor metabolizers. The opioid effect of (+)-M1 appears to contribute to the analgesic effect of tramadol, but the monoaminergic effect of tramadol itself seems to create an analgesic effect.
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Anesthesia and analgesia · Jan 2006
Comparative StudyThe efficacy and safety of intravenous emulsified isoflurane in rats.
Although direct IV injection of liquid volatile anesthetics is usually lethal, anesthesia using emulsified halothane and isoflurane without adverse effects has been safely induced in animals. We identified the safe concentration of emulsified volatile anesthetic preparations and determined the dose-response relationship of IV emulsified isoflurane and propofol in rats. Liquid/gas partition coefficients of desflurane, sevoflurane, isoflurane, enflurane, and halothane in 20% and 30% Intralipid were measured and used to calculate their saturated concentrations. ⋯ Time to return of forepaw righting reflex after injection of emulsified isoflurane (38 +/- 18 s) was significantly shorter than with propofol (101 +/- 62 s; P < 0.05). Anesthesia was successfully induced in rats by IV emulsified isoflurane with a comparable safety index and certain safety factor as propofol. Recovery of anesthesia after IV emulsified isoflurane was faster than with propofol.
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Anesthesia and analgesia · Jan 2006
The safety and efficacy of spinal anesthesia for surgery in infants: the Vermont Infant Spinal Registry.
Studies with modest numbers of patients have suggested that spinal anesthesia in infants is associated with a very infrequent incidence of complications, such as hypoxemia, bradycardia, and postoperative apnea. Although spinal anesthesia would seem to be a logical alternative to general anesthesia for many surgical procedures, it remains an underutilized technique. Since 1978, clinical data concerning all infants undergoing spinal anesthesia at the University of Vermont have been prospectively recorded. ⋯ This study confirms the infrequent incidence of complications associated with spinal anesthesia in infants. Spinal anesthesia can be performed safely, efficiently, and with the expectation of a high degree of success. Spinal anesthesia should be strongly considered as an alternative to general anesthesia for lower abdominal and lower extremity surgery in infants.