Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2002
Age-stratified pharmacokinetics of ketorolac tromethamine in pediatric surgical patients.
Published data suggest that ketorolac pharmacokinetics are different in children than in adults. We sought to better characterize ketorolac pharmacokinetics in children. Thirty-six children, aged 1-16 yr, were stratified into four age groups: 1-3 yr, 4-7 yr, 8-11 yr, and 12-16 yr. Each child received 0.5 mg/kg of ketorolac tromethamine IV after completion of elective surgery. A maximum of 16 venous blood samples (mean, 13 +/- 2) were collected at predetermined times up to 10 h after drug administration. Plasma ketorolac concentrations were measured by high-performance liquid chromatography after solid-phase extraction. Individual concentration-versus-time relationships were best fit to a two-compartment pharmacokinetic model by using SAAM II. Body weight-normalized pharmacokinetic variables did not differ among the age groups and were similar to those reported for adults, including a volume of distribution at steady state of 113 +/- 33 mL/kg (mean +/- SD) and an elimination clearance of 0.57 +/- 0.17 mL x min(-1) x kg(-1). Our study demonstrates that a single dose of ketorolac (0.5 mg/kg) results in plasma concentrations in the adult therapeutic concentration range for 6 h in most children. Our data provide no evidence that children require either larger weight-adjusted doses or shorter dosing intervals than adults to provide similar plasma drug concentrations. ⋯ The literature suggests that ketorolac disposition differs between children and adults. We characterized ketorolac pharmacokinetics in 36 children. Body weight-normalized two-compartment pharmacokinetic variables did not differ among pediatric patients <17 yr old and were similar to adult values.
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Anesthesia and analgesia · Feb 2002
Screening patients with prolonged neuromuscular blockade after succinylcholine and mivacurium.
Patients with pseudocholinesterase (BChE) variants may exhibit markedly prolonged paralysis after the administration of succinylcholine or mivacurium. We sought to evaluate to what extent molecular biology may contribute to the biological assessment of such patients. We conducted a prospective cohort study in patients referred to our center between 1995 and 1999 for prolonged neuromuscular blockade after mivacurium or succinylcholine. For each patient, phenotyping was performed with a conventional biochemical technique and molecular biology for the detection of the atypical mutation (A variant). Among the 36 patients referred, 31 had low BChE activity, 26 had received mivacurium (BChE activity, 2.1 U/mL; 0.3-4.3 U/mL), and 5 had received succinylcholine (BChE activity, 1.9 U/mL; 1.1-3.2 U/mL) (mean; extreme values). The mean clinical duration of paralysis was 90 min (40-140 min) after succinylcholine and 301 min (120-720 min) after mivacurium. Thirty-two patients had a BChE deficiency of genetic origin: 20 were homozygous (AA), 10 were heterozygous (UA) for the A variant, and 2 did not have the A mutation (UU). One heterozygous UA patient had normal BChE activity. Nine among the heterozygous UA and the two homozygous UU patients probably carried a not-screened variant. In most cases, biochemical diagnosis was sufficient to confirm the existence of constitutional deficiency; molecular biology improved the accuracy of diagnosis in 11 patients (30%) but had few or no clinical implications for the patient him- or herself. ⋯ Systematic screening for the pseudocholinesterase atypical variant by biochemical and DNA analysis after a prolonged neuromuscular blocking effect of succinylcholine or mivacurium shows that molecular biology could improve the diagnosis in approximately one third of patients, but with few clinical implications, compared with biochemical testing.
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Anesthesia and analgesia · Feb 2002
Case ReportsMelatonin for treatment and prevention of postoperative delirium.
Postoperative delirium is a common problem associated with increased morbidity and mortality, prolonged hospital stay, additional tests and consultations and therefore, increased cost (1,2). The reported incidence of delirium or confusion after surgery ranges from 8% to 78% (2,3-5), depending on methods and population studied. The elderly seem to be at significantly increased risk for this complication. Sleep-wake cycle disruption has been associated with delirium and behavioral changes (5) and sleep deprivation can even result in psychosis (6). Environmental changes (i.e., hospital stay), medications, and general anesthesia can affect the sleep-wake cycle (3,4). Plasma melatonin levels, which play an important role in the regulation of the sleep-wake cycle, are decreased after surgery (18) and in hospitalized patients (7,11). We report the successful use of melatonin in treating severe postoperative delirium unresponsive to antipsychotics or benzodiazepines in one patient. In another patient with a history of postoperative delirium, melatonin was used to prevent another episode of delirium after repeat lower extremity surgery. ⋯ Postoperative delirium or confusion after surgery is a common problem associated with complications and death. Delirium has been linked to sleep-wake cycle disruption. Melatonin levels, which play an important role in regulating the sleep-wake cycle, are decreased after surgery. Two cases are presented where melatonin was used to treat and prevent postoperative delirium.
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Anesthesia and analgesia · Feb 2002
The effects of the simulated Valsalva maneuver, liver compression, and/or Trendelenburg position on the cross-sectional area of the internal jugular vein in infants and young children.
We calculated the effects of the simulated Valsalva (V), liver (L) compression, and Trendelenburg (T) position on the cross-sectional area (CSA) of the right internal jugular vein by using planimetry (Aloka ultrasound machine) in 84 infants and young children. Eight combinations of positions and interventions were studied for each patient, with the patient supine, in the T position, during the simulated V maneuver, with L compression and a combination of maneuvers. Data were analyzed by using Friedman's chi(2) test and Wilcoxon's signed rank test. An increase of >25% in the CSA of the internal jugular vein was considered significant. In infants, the maximal mean increase achieved with the combination of all 3 maneuvers was only 17.4% +/- 16.1%. As a single maneuver, the simulated V was the most effective (11.6% +/- 11.5%). In children, the combination of all 3 maneuvers performed simultaneously produced a mean 65.9% (SD +/- 44.7%) increase in the CSA, which was larger than the increase by all other maneuvers alone or in a single combination (Friedman's test, P < 0.001 and Wilcoxon's test, P < 0.002). As a single maneuver, V produced the most increase (40.4% +/- 32.2%) compared with L compression (14.3% +/- 18.9%) or T position (24.3% +/- 27.1%). ⋯ The combinations of simulated Valsalva, liver compression, and Trendelenburg maneuvers produce the maximal mean increase in the size of the internal jugular vein in infants and young children, with the Valsalva maneuver being the most effective single maneuver. This increase is significant in young children, but negligible in infants.