Anesthesia and analgesia
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Anesthesia and analgesia · May 2003
Anesthetic technique influences brain temperature, independently of core temperature, during craniotomy in cats.
Because anesthetic technique has the potential to dramatically affect cerebral blood flow and metabolism (two determinants of brain thermoregulation), we tested the hypothesis that, after craniotomy, anesthetic technique would influence brain temperature independent of core temperature. Twenty-one cats (2.7 +/- 0.4 kg; mean +/- SD) undergoing a uniform right parasagittal craniotomy received 1) halothane 1.5% end-expired and normocapnia (HN), 2) halothane 1.5% and hypocapnia (HH), or 3) large-dose pentobarbital and normocapnia (PN) (n = 7 per group). Heating devices initially maintained core and right subdural normothermia (38.0 degrees C). Thereafter, cranial heating was discontinued. Brain-to-core temperature gradients during the 3 h study were greatest in the right subdural area, averaging -2.5 degrees C +/- 0.9 degrees C in HN, -2.5 degrees C +/- 0.8 degrees C in HH, and -4.1 degrees C +/- 1.1 degrees C in PN. Gradients within the unexposed left subdural area and in the right cortex 0.5 and 1.0 cm below the brain surface were -0.8 degrees C +/- 0.5 degrees C to -1.1 degrees C +/- 0.6 degrees C for both HN and HH but were twice this amount in PN (-1.9 degrees C +/- 0.5 degrees C to -2.1 degrees C +/- 0.7 degrees C) (P < 0.05 for PN versus HN and HH). Deep barbiturate anesthesia can reduce brain temperature independently of core temperature, presumably by reducing the metabolic rate and associated brain heat production. The magnitude is sufficient to augment any direct cerebroprotective properties of the barbiturates. ⋯ Deep barbiturate anesthesia reduced brain temperature independently of body temperature in cats and significantly more than the reduction seen with halothane anesthesia. The magnitude of temperature reduction was sufficient to account for cerebral protection by barbiturates independently of any other properties of the drug.
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Anesthesia and analgesia · May 2003
The influence of hemorrhagic shock on etomidate: a pharmacokinetic and pharmacodynamic analysis.
We studied the influence of hemorrhagic shock on the pharmacology of etomidate in swine. Sixteen swine were randomly assigned to control and shock groups. The shock group was bled to a mean arterial blood pressure of 50 mm Hg and held there until 30 mL/kg blood was removed. Etomidate 300 micro g x kg(-1) x min(-1) was infused for 10 min to both groups. Fifteen arterial samples were collected until 180 min after the infusion began to determine drug concentration. Pharmacokinetic variables for each group were estimated by using a three-compartment model. The bispectral index scale was used as a measure of drug effect. The pharmacodynamics were characterized by using a sigmoid inhibitory maximal effect model. The raw data revealed a 25% increase in the plasma etomidate concentration at the end of the 10-min infusion which resolved after termination of the infusion in the shock group. The pharmacokinetic analysis revealed subtle changes in the variable estimates between groups. The etomidate infusion produced a similar Bispectral Index Scale change in both groups. These results demonstrated that, unlike the influence of hemorrhagic shock on other sedative hypnotics and opioids, moderate hemorrhagic shock produced minimal changes in the pharmacokinetics and no change in the pharmacodynamics of etomidate. ⋯ Hemorrhagic shock produced minimal changes in the pharmacokinetics and no change in the pharmacodynamics of etomidate in swine. These results suggest that, unlike other sedative hypnotics and opioids, minimal adjustment in the dose of etomidate is required to achieve the same drug effect during hemorrhagic shock.
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Anesthesia and analgesia · May 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe influence of local active warming on pain relief of patients with cholelithiasis during rescue transport.
Upper abdominal pain, a frequent symptom of the presence of gallstone disease, is the cause of 6% of the emergency calls of the Austrian emergency system. Pain resulting from cholelithiasis is characteristically severe. Recent data show that active warming during emergency transport of trauma victims is effective in reducing pain. Therefore, we hypothesized that local active warming of the abdomen would be an effective pain treatment for patients with acute cholelithiasis and could be provided by paramedics. Sixty patients (>19 yr) consented to participate in this study. They were divided into two groups: Group 1, who received active warming of the upper abdomen with a carbon-fiber warming blanket (42 degrees C), and Group 2, who received no warming of the abdomen. Neither group received any drug-based pain care. Patients were asked to rate their pain and anxiety by using visual analog scales (VAS). Statistical evaluation was performed with Student's t-test; P < 0.05 was considered significant. In Group 1, a significant (P < 0.01) pain reduction was recorded in all cases on a visual analog scale (VAS), from 86.8 +/- 5.5 mm to 41.2 +/- 16.2 mm. In Group 2, the patients' pain scores remained comparable, from 88.3 +/- 9.9 mm to 88.1 +/- 10.0 mm on a VAS. In comparing Group 1 with Group 2 on arrival at the hospital, pain scores showed a significant difference (P < 0.01). In Group 1, the VAS score changes for anxiety were significantly reduced (P < 0.01), from 82.7 +/- 10.8 mm before treatment to 39.0 +/- 14.0 mm after treatment. In Group 2, a nonsignificant change of this score was noted, from 84.5 +/- 14.6 mm to 83.5 +/- 8.4 mm. Comparing Group 1 with Group 2 on arrival at the hospital showed a significant difference in anxiety scores (P < 0.01). We conclude that local active warming is an effective and easy-to-learn treatment for pain resulting from acute cholelithiasis in emergency care. ⋯ Active local warming of the upper abdomen is an effective treatment for patients with cholelithiasis being transported to the hospital by paramedics who are not permitted to provide any drug-based pain care. We observed no negative side effects of this treatment.