Anesthesia and analgesia
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Anesthesia and analgesia · May 1996
Rapid core-to-peripheral tissue heat transfer during cutaneous cooling.
Perioperative thermal manipulations are usually directed at the skin surface because methods of directly warming the core are invasive or ineffective. However, inadequate heat flow between peripheral and core compartments will decrease the rate at which core temperature changes. We therefore determined whether core hypothermia is delayed after initiation of surface cooling. ⋯ There was no delay between initiation of active cooling and the decrease in core temperature. Furthermore, peripheral (arm and leg) and core (trunk and head) tissue heat contents decreased at virtually the same rates: approximately 50 kcal/h and approximately 47 kcal/h, respectively. These data indicate that there is little restriction of heat flow between peripheral and core tissues in vasodilated, anesthetized subjects.
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Anesthesia and analgesia · May 1996
Randomized Controlled Trial Clinical TrialBolus metoclopramide does not enhance morphine analgesia after cesarean section.
Intravenous metoclopramide potentiates the analgesic effects of opioids in postoperative patients. We speculate that increased spinal concentrations of acetylcholine from metoclopramide-induced acetylcholinesterase inhibition is the mechanism responsible for enhanced morphine analgesia from metoclopramide. Sixty patients undergoing elective cesarean section with subarachnoid anesthesia were randomized to receive either 20 mg metoclopramide or saline intravenously 30-60 min prior to subarachnoid injection. ⋯ CSF cholinesterase activity was similar to values in nonpregnant patients demonstrated previously. This study failed to confirm the morphine-enhancing action of 20 mg intravenous metoclopramide in postoperative patients. Furthermore, this dose of metoclopramide does not inhibit CSF acetylcholinesterase.
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Anesthesia and analgesia · May 1996
Tracheal extubation of children in the operating room after atrial septal defect repair as part of a clinical practice guideline.
Early tracheal extubation in the operating room after atrial septal defect (ASD) surgery was recommended as part of a clinical practice guideline (CPG) established in the Cardiovascular Program at the Children's Hospital, Boston, MA. This retrospective review was undertaken to determine whether this practice was efficient without compromising patient care. The charts and hospital charges for 102 patients undergoing secundum ASD or sinus venosus defect surgery between March 1992 and July 1994 were reviewed; 36 patients (Group I) had surgery prior to introduction of the CPG, and 66 patients were managed according to the CPG. ⋯ There was no difference among groups in the hospital charges for OR, anesthesia and CICU time. However, when the combined hospital charges for services provided both in the OR and CICU were included, patients in Group II were charged significantly less, and this primarily reflects the absence of postoperative mechanical ventilation charges. Tracheal extubation in the OR after ASD surgery in children can result in lower patient charges without significantly compromising patient care.
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Anesthesia and analgesia · May 1996
Comparative StudyInteraction of heart rate and hypothermia on global myocardial contraction of the isolated rabbit heart.
We studied the effects of mild hypothermia on cardiac contractility in isolated rabbit hearts perfused with Krebs-Henseleit solution according to the technique of Langendorff. Isovolumetric left ventricular pressure (LVP) was measured with a fluid-filled balloon. Hearts were paced after induction of atrioventricular block. ⋯ At pacing rates > or = 90 bpm, lower systolic LVP, higher diastolic LVP, and lower positive and negative LV dP/dt were obtained in hypothermic (93 +/- 12 mm Hg, 55 +/- 18 mm Hg, 584 +/- 137 mm Hg/s, and 323 +/- 57 mm Hg/s at 210 bpm, respectively) compared to normothermic hearts (123 +/- 4 mm Hg, 10 +/- 4 mm Hg, 1705 +/- 145.5 mm Hg/s, and 1155 +/- 78 mm Hg/s at 210 bpm, respectively.) The duration of mechanical diastole was reduced or suppressed in these hearts. Exposure to the beta-adrenoreceptor agonist, isoproterenol, improved this diastolic dysfunction during hypothermia and pacing at high rates, suggesting that the sarcoplasmic reticulum Ca2+ uptake might be involved. Our data are also consistent with an increase in myofilament Ca2+ sensitivity that is opposed by isoproterenol during hypothermia.
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Anesthesia and analgesia · May 1996
Auto-positive end-expiratory pressure during one-lung ventilation using a double-lumen endobronchial tube.
The present study was undertaken to investigate the possible relationships between the magnitude of autopositive end-expiratory pressure (auto-PEEP) and measured PaO2 during one-lung ventilation (OLV). Forty-one adults received OLV anesthesia using a tidal volume of 8 mL/kg and a respiratory rate of 12 breaths/min. Auto-PEEP was quantified using an end-expiratory port occlusion method. ⋯ Auto-PEEP during OLV correlated inversely with preoperative forced expiratory volume in 1 s/forced vital capacity (y = 12.5 - 0.13x, r = -.05, P < 0.005). During OLV, there was no significant correlation between auto-PEEP and measured PaO2. These findings confirm that many patients do not exhale completely to functional residual capacity during OLV.