Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2000
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of the incidence of the oculocardiac and oculorespiratory reflexes during sevoflurane or halothane anesthesia for strabismus surgery in children.
We examined changes in the cardiorespiratory system of small children during surgical correction of strabismus with a laryngeal mask airway and spontaneous respiration with sevoflurane or halothane inhaled anesthesia. Fifty-one children, 1-7 yr old, having outpatient strabismus correction were randomized to sevoflurane (S) or halothane (H) in 66% nitrous oxide at 1.3 minimum alveolar concentration. Children breathed spontaneously through a laryngeal mask airway and were not pretreated with anticholinergics. The oculocardiac reflex (OCR), defined as a 20% decrease in heart rate (HR) from baseline, dysrhythmias, or sinoatrial arrest concomitant with ocular muscle traction occurred less frequently with sevoflurane than with halothane (S 38%, H79%, P = 0.009). The baseline HR was higher with sevoflurane (S 114 +/- 13 bpm, H 101 +/- 15 bpm, P = 0.002). The lowest HR occurred with halothane (S 95 +/- 22 bpm, H 73 +/- 19 bpm, P = 0.001). The incidence of dysrhythmias was higher in the halothane group (S 4%, H 42%, P = 0.004). Reductions in minute ventilation and PETCO(2) accompanied OCRs. Airway irritability was present with halothane only (S 0, H 3). Eleven children, of whom the majority had received halothane, required measures to correct SpO(2) < 95% or PETCO(2) > 60 mm Hg during maintenance anesthesia (S 11%, H 32%). Sevoflurane may be a more suitable anesthetic than halothane for operations involving traction on the ocular muscles with spontaneous respiration in children because of reduced incidence of OCR, airway irritability, and ventilatory disturbances. ⋯ Some children experience a sudden slowing of the heart and impaired breathing when the surgeon pulls on the eye muscles during squint operations under anesthesia. Sevoflurane, a recently developed anesthetic vapor, may reduce this problem when compared with the established vapor halothane.
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Anesthesia and analgesia · Feb 2000
Randomized Controlled Trial Clinical TrialPrevention of hypotension by a single 5-mg dose of ephedrine during small-dose spinal anesthesia in prehydrated cesarean delivery patients.
To evaluate the effectiveness of prophylactic ephedrine for the prevention of hypotension associated with spinal anesthesia, 50 parturients undergoing cesarean delivery received either ephedrine 5 mg or saline IV in a double-blinded fashion immediately after the induction of spinal anesthesia. Spinal anesthesia was performed with hyperbaric bupivacaine 6.6 mg combined with sufentanil 3.3 microg as part of a combined spinal-epidural technique. All patients received 1000 mL of lactated Ringer's solution and 500 mL of hydroxyethylstarch 6% before the spinal injection. Additional ephedrine boluses (5 mg) were administered IV when the systolic blood pressure or heart rate decreased by more than 30% from baseline values, when systolic blood pressure became <100 mm Hg, or when patients complained of nausea or feeling faint. The height of the block was equal in the groups; however, more patients in the placebo group were found to develop hypotension (58% vs 25%, P < 0. 05). Only 2 (8%) patients in the ephedrine group developed hypotension with systolic blood pressure values <90 mm Hg, whereas 10 patients (42%) in the saline group experienced hypotension of this severity (P < 0.05). In addition, there was a higher incidence of nausea in the placebo-treated patients. The total amount of ephedrine administered did not differ between groups. These findings suggest that the incidence and severity of hypotension are significantly reduced by the IV administration of a prophylactic dose of 5 mg ephedrine in patients receiving small-dose spinal anesthesia for cesarean delivery. ⋯ Ephedrine is the drug most often used to correct hypotension during spinal anesthesia for cesarean delivery in healthy patients. A single IV dose of 5 mg decreases the occurrence and limits the severity of hypotension in prehydrated subjects receiving a small-dose spinal local anesthetic-opioid combination.
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Anesthesia and analgesia · Feb 2000
Randomized Controlled Trial Clinical TrialPropofol/sufentanil anesthesia suppresses the metabolic and endocrine response during, not after, lower abdominal surgery.
We investigated the influence of propofol/sufentanil anesthesia on metabolic and endocrine responses during, and immediately after, lower abdominal surgery. Twenty otherwise healthy patients undergoing abdominal hysterectomy for benign myoma received either continuous infusions of propofol supplemented with sufentanil (0.01 microg. kg(-1). min(-1), n = 10) or enflurane anesthesia (enflurane, n = 10). Plasma concentrations of glucose, lactate, free fatty acids, triglycerides, insulin, glucagon, cortisol, epinephrine, and norepinephrine were measured before, during, and 2 h after surgery. Pre- and postoperative endogenous glucose production (R(a) glucose) was analyzed by an isotope dilution technique by using [6,6-(2)H(2)] glucose. Propofol/sufentanil anesthesia prevented the increase in plasma cortisol and catecholamine concentrations and attenuated the hyperglycemic response during surgery without showing any difference after the operation. Mediated through a higher glucagon/insulin quotient (propofol/sufentanil 15 +/- 7 versus enflurane 8 +/- 4 pg/microU, P < 0.05), the R(a) glucose postoperatively increased more in the propofol/sufentanil than in the enflurane group (propofol/sufentanil 15.6 +/- 2.0 versus enflurane 13.4 +/- 2.2 micromol. kg(-1). min(-1), P < 0.05). ⋯ The concept of stress-free anesthesia using propofol combined with sufentanil is valid only during surgery. The metabolic endocrine stress response 2 h after the operation is more pronounced than after inhaled anesthesia.
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Anesthesia and analgesia · Feb 2000
Clinical TrialInterference of cerebral near-infrared oximetry in patients with icterus.
Near-infrared spectrophotometry assesses cerebral oxygen saturation (ScO(2)) based on the absorption spectra of oxygenated and deoxygenated hemoglobin and the translucency of biological tissue in the near-infrared band. In patients with icterus, however, bilirubin can potentially hinder cerebral oximetry. In 48 patients undergoing orthotopic liver transplantation, we related total plasma bilirubin to ScO(2) as determined from spectrophotometry with wavelengths of 733 and 809 nm. Before surgery, ScO(2) was 59% (15%-78%) (median with range) and bilirubin was 71 (6-619) micromol/L with a negative correlation (r = -0.72; P < 0.05). The 95% prediction interval included the lowest measurable ScO(2) of 15% at a bilirubin level of 370 micromol/L. During reperfusion of the grafted liver, the ScO(2) increased by 7% (-8% to 17%) (P < 0.05), and bilirubin did not influence this increase. In one patient, the ScO(2) remained below 15% despite a decrease in bilirubin from 619 to 125 micromol/L, suggesting that tissue pigmentation deposits also absorb light. In conclusion, bilirubin dampens the spectrophotometry-determined cerebral oxygen saturation at 733 and 809 nm. A bilirubin level of 370 micromol/L, tissue pigment deposits, or both, may render determination of cerebral oxygen saturation impossible. Even at high bilirubin values, changes in cerebral perfusion may be visible. ⋯ In 48 patients undergoing liver transplantation, the interference of icterus on cerebral oximetry by near-infrared light was investigated. Bilirubin absorbed the near-infrared light and lowered the measured cerebral oxygen saturation. Even at high bilirubin values, changes in cerebral oxygenation, as seen during reperfusion of the grafted liver, may be visible.