Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1992
Thermoregulatory vasoconstriction during propofol/nitrous oxide anesthesia in humans: threshold and oxyhemoglobin saturation.
To determine the thermoregulatory effects of propofol and nitrous oxide, we measured the threshold for peripheral vasoconstriction in seven volunteers over a total of 13 study days. We also evaluated the effect of vasoconstriction on oxyhemoglobin saturation (SpO2). Anesthesia was induced with an intravenous bolus dose of propofol (2 mg/kg), followed by an infusion of 180 micrograms.kg-1 x min-1 for 15 min, and maintained with 60% nitrous oxide and propofol (80-160 micrograms.kg-1 x min-1). ⋯ These data suggest that anesthesia with propofol, in typical clinical concentrations, and 60% nitrous oxide substantially inhibits thermoregulatory vasoconstriction. Vasoconstriction increased SpO2 by approximately 2% without a significant concomitant change in PO2. The observed increase in SpO2 probably reflects decreased transmission of arterial pulsations to venous blood in the finger.
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Anesthesia and analgesia · Dec 1992
Randomized Controlled Trial Clinical TrialIntramuscularly administered dexmedetomidine attenuates hemodynamic and stress hormone responses to gynecologic laparoscopy.
The hemodynamic and endocrine effects of three different doses of dexmedetomidine (0.6, 1.2, and 2.4 micrograms/kg), oxycodone (0.13 mg/kg), and saline solution, injected intramuscularly 45-60 min before induction of general anesthesia, were compared in a double-blind, randomized study involving 100 women undergoing gynecologic diagnostic laparoscopy. Anesthesia was induced with thiopental (4.5 mg/kg) and maintained with 0.3% end-tidal isoflurane and 70% nitrous oxide in oxygen. Arterial blood pressure and heart rate increased after endotracheal intubation and during laparoscopy in all groups, but the maximal mean arterial pressure after tracheal intubation was lower in the dexmedetomidine 2.4-micrograms/kg group (104 mm Hg [SD 19]) than in the saline solution group (130 mm Hg [SD 12]). ⋯ On the other hand, 40% of the patients in the dexmedetomidine 2.4-micrograms/kg group received atropine in the postanesthesia care unit for bradycardia (heart rate < or = 40 beats/min). Preoperative anxiety and sedation before and after preanesthetic medication were evaluated by the patients with the aid of a profile of mood-state questionnaire; only dexmedetomidine 2.4 micrograms/kg produced significant anxiolysis and sedation. Plasma concentrations of norepinephrine, epinephrine, 3,4-dihydroxyphenylglycol, cortisol, and beta-endorphin increased less in the dexmedetomidine 2.4-micrograms/kg group in response to tracheal intubation and surgery than in the saline solution group.
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Anesthesia and analgesia · Dec 1992
Randomized Controlled Trial Clinical TrialEffectiveness of preoperative sedation with rectal midazolam, ketamine, or their combination in young children.
To determine which of three types of rectal sedation was most effective preoperatively in facilitating parental separation and intravenous cannulation in young children, 100 children 3.0 +/- 1.7 (mean +/- SD) yr of age were randomly assigned to four equal groups. One group (M-K-A) received rectal midazolam (0.5 mg/kg), ketamine (3 mg/kg), and atropine (0.02 mg/kg). The other sedation groups received the same doses of midazolam and atropine (M-A) or ketamine and atropine (K-A) alone, and the control group (A) received only rectal atropine. ⋯ Intravenous catheter placement was also successful significantly more often in the M-A (80%) and M-K-A (84%) groups than in the K-A (48%) or A (40%) groups. Complications were similar among the groups, but there was evidence that midazolam prolonged recovery time in some patients. Rectal midazolam with or without ketamine is a useful technique when intravenous catheter placement before induction of anesthesia is desired.
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Anesthesia and analgesia · Dec 1992
Randomized Controlled Trial Clinical TrialDexmedetomidine infusion for maintenance of anesthesia in patients undergoing abdominal hysterectomy.
The usefulness of intravenous dexmedetomidine infusion for maintenance of anesthesia was studied in patients anesthetized with thiopental, fentanyl, nitrous oxide, and oxygen. Isoflurane was added as needed. The study was conducted in two parts, the first of which was an open dose-response study that comprised 14 women undergoing abdominal hysterectomy. ⋯ Isoflurane was administered according to predetermined hemodynamic criteria. Dexmedetomidine infusion did not completely abolish the need for isoflurane but diminished its requirement by > 90% (P = 0.02). The heart rate response to endotracheal intubation was significantly blunted.
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Extracorporeal membrane oxygenation is still a relatively new technology that has recently achieved recognition after initial clinical disappointment in the late 1970s. At present, it is considered standard therapy for the full-term infant with PPHN who fails CMV and extraordinary, heroic therapy for older children and adults with ARF or cardiac failure, or both. ⋯ Areas of interest include heparinless circuits, carotid artery reconstruction, improved monitoring, and expanding applications of VV ECMO. As ECMO becomes safer and more effective, it is believed that new and expanding patient populations will emerge to include premature infants, earlier intervention in term infants, and more liberal application to pediatric and adult populations.