Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1997
Randomized Controlled Trial Clinical TrialThe effects of reversal of neuromuscular blockade on autonomic control in the perioperative period.
Impaired parasympathetic control of heart rate is associated with increased incidence of cardiac dysrhythmias and ischemia. Anticholinergic drugs suppress parasympathetic control and could be detrimental in the early postoperative period in high-risk patients. In this double-blind randomized trial, 30 ASA physical status I and II patients undergoing minor surgery received either atropine 20 micrograms/kg and neostigmine 50 micrograms/kg (Group A), glycopyrrolate 8 micrograms/kg and neostigmine 50 micrograms/kg (Group G), or placebo (Group P) for reversal of neuromuscular blockade. ⋯ Groups A and G showed a borderline decrease in normalized high-frequency variability at 2 h (P = 0.05 for Groups A and G versus Group P). Anticholinergic drugs with neostigmine cause impairment of parasympathetic control of heart rate which persists into the early postoperative period. The effects of glycopyrrolate appear to be of shorter duration; this drug may thus be preferable in patients at risk of cardiovascular complications.
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Anesthesia and analgesia · Jan 1997
Randomized Controlled Trial Comparative Study Clinical TrialPrevention of spinal anesthesia-induced hypotension in the elderly: comparison between preanesthetic administration of crystalloids, colloids, and no prehydration.
The practice of routinely prehydrating patients by infusing a crystalloid or colloid solution (up to 1.0 L/70 kg) for prevention of spinal anesthesia-induced hypotension has been challenged recently, after several reports of failure to demonstrate its efficacy in young women. We compared the incidence and frequency of hypotension and vasopressor therapy after spinal anesthesia and no prehydration with crystalloid and colloid prehydration in elderly patients. Eighty-five ASA grade I or II patients (aged 60-89 yr) for elective total hip replacement were randomized to receive 500 mL crystalloid solution (Hartmanns, n = 29), 500 mL colloid (Haemaccel, n = 28), or no prehydration (n = 28) over 10 min prior to spinal anesthesia. ⋯ Although absolute systolic BP readings were significantly higher in the colloid group between 6 and 30 min (P < 0.05), the incidence of hypotension was not significantly different between the groups. The incidence of ephedrine use, incidence of nausea/vomiting, and median total dose of ephedrine were similar in all groups. We conclude that, in elderly patients undergoing elective procedures, withholding prehydration is not associated with any greater degree of hypotension or need for vasopressor therapy compared with crystalloid or colloid prehydration.
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Anesthesia and analgesia · Jan 1997
Randomized Controlled Trial Comparative Study Clinical TrialPrevention of hypotension during spinal anesthesia: a comparison of intravascular administration of hetastarch versus lactated Ringer's solution.
This study was designed to compare the efficacy of 6% hetastarch to that of crystalloid administration in reducing the incidence and severity of hypotension during spinal anesthesia. Forty ASA grade I patients scheduled for postpartum tubal ligations under spinal anesthesia were randomly allocated to receive either 500 mL of hetastarch solution or 1000 mL of lactated Ringer's solution prior to spinal anesthesia. Spinal anesthesia was managed identically in both groups by anesthesiologists who were unaware of the type of fluid administered. ⋯ The difference in the incidence of hypotension was significant (P < 0.05). The requirement of 5-mg bolus doses of ephedrine to maintain systolic arterial blood pressure > 75% of baseline was significantly greater in the lactated Ringer's group than in the hetastarch group (15 vs 4, P < 0.05). We conclude that an intravenous infusion of 500 mL of 6% hetastarch solution is more effective than 1000 mL lactated Ringer's solution in attenuating spinal anesthesia induced hypotension in women undergoing postpartum tubal ligation.
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Anesthesia and analgesia · Jan 1997
Randomized Controlled Trial Clinical TrialThe duration of impairment of autonomic control after anticholinergic drug administration in humans.
Impaired parasympathetic control of heart rate is associated with increased incidence of cardiac dysrhythmias and ischemia. Anticholinergic drugs, commonly administered during reversal of neuromuscular blockade, suppress parasympathetic control in the early postoperative period. This could potentially be detrimental in patients at risk of cardiovascular complications. ⋯ Both drugs resulted in a marked decrease in baroreflex sensitivity and high-frequency heart rate variability. The times to return to baseline values were approximately doubled after atropine compared to glycopyrrolate (177 +/- 22 vs 82 +/- 8 min for baroreflex sensitivity, 212 +/- 16 vs 111 +/- 14 min for high-frequency power, and 171 +/- 18 vs 95 +/- 18 min for high-frequency power normalized to total power; P < 0.01 for all variables). Atropine leads to more prolonged impairment of parasympathetic control than equipotent doses of glycopyrrolate, and its use may thus be less desirable in high-risk patients in the early postoperative period.
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Anesthesia and analgesia · Jan 1997
Randomized Controlled Trial Clinical TrialSmall-dose propofol by continuous infusion does not prevent postoperative vomiting in females undergoing outpatient laparoscopy.
This study was designed to test the hypothesis that there is a direct prophylactic antiemetic effect of small-dose propofol given by continuous infusion. Sixty female patients undergoing outpatient laparoscopy under general anesthesia were randomized to receive, in a double-blind fashion, either a bolus of 0.1 mg/kg followed by a constant infusion of 1 mg.kg-1.h-1 of propofol or an equivalent volume of 10% Intralipid (placebo) beginning 30 min before induction of anesthesia and continuing until discharge from Stage I postanesthesia care unit (PACU). Anesthesia was induced and maintained in a standard fashion in all patients. ⋯ No significant differences between Intralipid and propofol were found for any of the outcome variables tested. While small-dose propofol is an effective adjuvant in reducing chemotherapy-induced emesis, we were unable to demonstrate any beneficial effect of propofol in reducing postoperative nausea and vomiting when used as the sole prophylactic medication in this patient population. Propofol may have a synergistic effect when administered with other antiemetics, or the specific antiemetic effect of propofol, if it exists, may be dose-dependent and the dose used in this study was below the efficacy threshold.