Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Clinical TrialOral midazolam premedication in preadolescents and adolescents.
We sought to determine the influence of preoperative oral midazolam on 1) sedation score, 2) measures of anesthetic emergence, 3) recovery times, and 4) bispectral index (BIS) measurements during sevoflurane/N(2)O anesthesia in adolescent patients. Fifty ASA I and II patients 10-18 yr of age were enrolled in a prospective double-blinded study. Patients were randomized to receive either 20 mg of midazolam (M group) or midazolam vehicle (P group) as premedication. Before the induction, sedation scores and BIS values were determined in all patients. After inhaled induction and intubation, expired sevoflurane was stabilized at 3% in 60% N(2)O and the corresponding BIS (BIS I) recorded. Upon completion of surgery, sevoflurane was stabilized at 0.5% and the BIS (BIS E) again recorded. Plasma midazolam levels were measured at the time of BIS I and BIS E. There were no significant differences between groups in awakening time, sevoflurane/N(2)O awakening concentrations, time to postanesthesia care unit discharge, or BIS I and BIS E measurements. Sedation scores and preinduction BIS values were significantly lower in Group M than in Group P, although only 40% of midazolam-treated patients exhibited detectable sedation, with marked interindividual variability in achieved plasma midazolam levels. Detectable preoperative sedation was predictive of delayed emergence. ⋯ We demonstrated a measurable sedative effect of oral midazolam in adolescents which correlated with simultaneous bispectral index (BIS) measurement. Considering the overall group, midazolam premedication did not affect intraoperative BIS, emergence times, or recovery times compared with placebo controls. Detectable preoperative sedation, and not merely midazolam administration, was predictive of prolonged emergence.
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Clinical TrialCisapride does not prevent postoperative vomiting in children.
The peripherally acting prokinetic drug cisapride can overcome opioid-induced gastrointestinal paresis and may thereby eliminate a stimulus for postoperative vomiting. We conducted a prospective, randomized, double-blinded, controlled trial of 96 children undergoing inguinal surgery to determine whether cisapride would reduce the incidence of postoperative vomiting after general anesthesia supplemented with morphine. Group C1 patients (n = 38) received cisapride 0.3 mg/kg orally 1 h before surgery and placebo 6 h later, Group C2 (n = 28) received cisapride both before and after surgery, and Group P (n = 30) received placebo. Mean age (5.0 +/- 2.7 yr) and weight (21.0 +/- 8.6 kg), median pain scores and parent satisfaction scores, and incidence of rescue analgesic administration were similar across groups. Contrary to our hypothesis, incidences of postoperative vomiting in the hospital (32% vs 20%, P = 0.33) and at home (53% vs 46%, P = 0.33) did not vary by treatment group (with [C1 and C2] and without [P] cisapride, respectively). There was a trend toward more severe postoperative vomiting (three or more episodes) in children who received cisapride versus those who did not, both in hospital (6% vs 0%, P = 0.3) and at home (22% vs 8%) (P = 0.13). We conclude that cisapride does not prevent postoperative vomiting in this patient population and speculate that factors other than reduced gastrointestinal motility associated with general anesthesia and opioids are more important determinants of postoperative vomiting. ⋯ Cisapride does not prevent postoperative vomiting in children and may increase its severity.
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Clinical TrialThe effects of three different analgesia techniques on long-term postthoracotomy pain.
In this clinical, randomized, prospective study, we compared the effects of three different analgesia techniques (thoracic epidural analgesia [TEA] with and without preoperative initiation and IV patient-controlled analgesia [IV-PCA]) on postthoracotomy pain in 69 patients. In two groups, a thoracic epidural catheter was inserted preoperatively. Group Pre-TEA had bupivacaine and morphine solution preoperatively and intraoperatively. Postoperative analgesia was maintained with epidural PCA with a similar solution. Group Post-TEA, with no intraoperative medication, had the same postoperative analgesia as Group Pre-TEA plus the bolus dose. Group IV-PCA received only IV-PCA with morphine for postoperative analgesia. Pain was evaluated every 4 h during the first 48 h at rest, cough, and movement. Pre-TEA was associated with decreased pain compared with the other groups. Six months later, the patients were asked about their pain. The incidence and the intensity of pain were most frequent in Group IV-PCA (78%) and were the least in Group Pre-TEA (45%) (Group Pre-TEA versus Group IV-PCA, P = 0.0233; Group Pre-TEA versus Group IV-PCA, P = 0.014). Patients having pain on the second postoperative day had 83% chronic pain. TEA with preoperative initiation is a preferable method in preventing acute and long-term thoracotomy pain. ⋯ Preoperatively initiated thoracic epidural analgesia has the most satisfying results in controlling postthoracotomy pain in the acute and long-term period, and it is associated with a decreased incidence (and intensity) of chronic pain compared with postoperative (epidural or IV) analgesia. Chronic pain has an incidence of 62%.
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Anesthesia and analgesia · Jan 2002
Physiologic characteristics of cold perfluorocarbon-induced hypothermia during partial liquid ventilation in normal rabbits.
Because perfluorocarbon (PFC) liquid contacts closely with the alveolar capillaries during partial liquid ventilation (PLV), PLV with cold PFC may be used for the induction of hypothermia. Twenty rabbits were randomized to PFC-induced hypothermia (PH) (n = 7; core temperature 35 degrees +/- 1 degrees C), surface hypothermia (SH) (n = 7; 35 degrees +/- 1 degrees C), or normothermia (n = 6; 39 degrees +/- 1 degrees C). We induced PH by repeated in situ exchanges of 0 degrees C perfluorodecalin during PLV. At the establishment (0 min) of hypothermia in the PH group, oxygen consumption (P = 0.04) and oxygen extraction ratio (P = 0.01) decreased from normothermic condition. Metabolic (oxygen consumption, oxygen extraction ratio, serum lactate level) and hemodynamic variables (heart rate, blood pressure, cardiac output, pulmonary artery pressure) of the PH group were not different from those of the SH group at 0, 30, 60, 90, and 120 min of hypothermia. The difference in temperature between the pulmonary artery and rectum during the hypothermic period was smaller in the PH group compared with the SH group (P = 0.033). In conclusion, hypothermia may be induced during PLV by using cold PFC. This "pulmonary method" of cooling was comparable to a systemic method of cooling with regard to a few important physiologic variables, while maintaining a narrower interorgan temperature difference. ⋯ The induction of moderate hypothermia was feasible in rabbits by administrating cold perfluorocarbon liquid into the lung. Physiologic changes induced by this pulmonary cooling were comparable to those induced by systemic cooling. Our method may be regarded as a methodological advance in the field of therapeutic hypothermia.
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Anesthesia and analgesia · Jan 2002
Bispectral index values and spectral edge frequency at different stages of physiologic sleep.
Bispectral index (BIS) and spectral edge frequency (SEF) are used as measures of depth of anesthesia and sedation. We tested whether these signals could predict physiologic sleep stages, by taking processed electroencephalogram measurements and recording full polysomnography through a night's sleep in 10 subjects being investigated for mild sleep apnea/hypopnea syndrome. Computerized polysomnograph signals were analyzed manually according to standard criteria, classifying each 30-s epoch as a specific sleep stage. The BIS and SEF values were taken at the end of each period of sleep when the same stage had lasted for at least 2 min. Before sleep, median values for BIS were 97 +/- 12.1 and for SEF 23 +/- 4.2 Hz. After sleep initiation, the median BIS values for arousal, light, slow wave, and rapid eye movement sleep were 67 +/- 20.2, 50 +/- 16.5, 42 +/- 11.2, and 48 +/- 7.1, respectively, and the median SEF values were 20 +/- 4.7, 15 +/- 3.6, 10 +/- 2.6, and 19 +/- 4.1 Hz, respectively. Although both BIS and SEF decreased with increasing sleep depth, the distribution of values at each sleep depth was considerable, with overlap between each sleep stage. Neither BIS nor SEF reliably indicated conventionally determined sleep stages. In addition, the response of the BIS was slow and patients could arouse with low BIS values, which then took some time to increase. ⋯ Although computer processing of the electroencephalogram can provide an adequate index of depth of anesthesia, the same processing cannot reliably convey depth of natural sleep. At each sleep stage, the output signal has a wide range of possible values.