Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1995
Randomized Controlled Trial Comparative Study Clinical TrialRenal function and serum fluoride concentrations in patients with stable renal insufficiency after anesthesia with sevoflurane or enflurane.
Sevoflurane is metabolized to hexa-fluoro-isopropanol and inorganic fluoride by the human liver. Its use as an anesthetic may lead to peak plasma fluoride concentrations exceeding those seen after enflurane. Although there is no nephrotoxicity after sevoflurane anesthesia in humans with normal kidneys, those with chronically impaired renal function might be at increased risk because of increased fluoride load due to prolonged elimination half-life. ⋯ No patient suffered a permanent deterioration of preexisting renal insufficiency and none required dialysis. Thus, neither sevoflurane nor enflurane deteriorated postoperative renal function in these patients with preexisting renal insufficiency. There is no evidence that fluoride released by metabolism of sevoflurane metabolism worsened renal function in these patients with stable, permanent serum creatinine concentrations more than 1.5 mg/dL.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Sep 1995
Randomized Controlled Trial Comparative Study Clinical TrialComparison of propofol administration techniques for sedation during monitored anesthesia care.
Sixty-three outpatients undergoing breast biopsy procedures with local anesthesia were randomly assigned to receive propofol by intermittent bolus injections (n = 21), a conventional syringe infusion pump (n = 21), or a target-controlled infusion (TCI) device (n = 21) for intraoperative sedation. In the first two groups, an initial intravenous (IV) bolus of propofol (0.3 mg/kg) was administered and an attempt was made to maintain the sedation level at an Observer's Assessment of Alertness/Sedation (OAA/S) score of 3 or 4 with either intermittent bolus injections of propofol (10 mg) or a variable-rate infusion (25-100 micrograms.kg-1.min-1). In the TCI group, the initial target concentration of propofol was set at 2 micrograms/mL and the target concentration was adjusted between 1 and 4 micrograms/mL in an attempt to maintain an OAA/S score of 3 or 4. ⋯ The anesthesiologist had to intervene more frequently in the intermittent bolus injection group than in the two infusion groups. We conclude that the use of an infusion technique may allow the anesthesiologist more time for monitoring the patient by decreasing the number of interventions necessary to administer supplemental doses of the sedative medication during the operation. However, the cost of the IV drug delivery system may become an increasingly important factor in the future.
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Anesthesia and analgesia · Sep 1995
Temperature corrected thrombelastography in hypothermic patients.
Thrombelastograms and other coagulation studies are performed at 37 degrees C, regardless of the patient's body temperature. This prospective study of 45 patients undergoing orthotopic liver transplantation was conducted to evaluate the effect on the thrombelastogram performed at the patient's actual body temperature compared with a control thrombelastogram heated in the standard fashion to 37 degrees C. Thrombelastograms were obtained after the induction of anesthesia and at various times throughout the operation when clinically indicated. ⋯ The variables of the thrombelastogram measured were: r (reaction time in minutes), r + K (coagulation time in minutes), alpha (coagulation rate in degrees), and MA (maximum amplitude in millimeters). Whenever the patient's body temperature was less than 37 degrees C, statistically significant prolongation of the reaction time, coagulation time, and decrease in the clot formation rate occurred compared with control variables at 37 degrees C. Overall means were as follows: r for control, 8.24 +/- 0.28 min; r for temperature corrected, 9.32 +/- 0.27 min; r + K for control, 15.4 +/- 0.65 min; r + K for temperature corrected, 17.5 +/- 0.81 min; and alpha for control, 39.8 +/- 1.22 degrees; alpha for temperature corrected, 37.7 +/- 1.23 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Sep 1995
Isoflurane and sevoflurane produce a dose-dependent reduction in the shivering threshold in rabbits.
All general anesthetics markedly impair thermoregulatory responses; nonetheless, sufficient hyperthermia or hypothermia will trigger most protective reflexes. Shivering, however, remains an exception among thermo-regulatory responses: it is common during postanesthetic recovery, but is rare at typical anesthetic concentrations. This observation suggests that general anesthesia impairs shivering far more than other thermoregulatory defenses. ⋯ Four of the six rabbits given 0.3 MAC isoflurane shivered at a mean core temperature of 36.2 +/- 0.6 degrees C, and two of these rabbits failed to shiver at a minimum core temperature of 35.0 degrees C. However, no rabbit given 0.4 MAC isoflurane shivered, even at minimum core temperatures of 35.0 degrees C. All of the rabbits given 0.2 MAC sevoflurane shivered at a mean core temperature of 36.6 +/- 0.7 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Sep 1995
Comparative StudyComparison of needle deviation during regional anesthetic techniques in a laboratory model.
Although many characteristics of needles used for spinal and epidural anesthesia have been studied extensively, the amount that a needle deviates from a straight path while passing through tissue has been relatively ignored. A laboratory model was used to determine the amount of needle deviation produced when different types of new spinal needles and epidural needles were passed through porcine tissue. ⋯ Needles commonly used for epidural anesthesia (Tuohy, Hustead, Crawford) exhibited increased deviation (range 1.73-3.54 mm/50 mm tissue), although the largest amount was seen with beveled spinal needles (Quincke, Atraucan) (range 4.42-5.90 mm/50 mm tissue). The possible clinical significance of needle deviation during the performance of a regional anesthetic is discussed.