Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2001
Randomized Controlled Trial Clinical TrialThe efficacy of simulated intravascular test dose in sedated patients.
Sedation usually decreases the reliability of subjectively detecting an intravascular test dose, but the efficacies of objective hemodynamic and T-wave criteria remain undetermined. Sixty healthy patients were randomly assigned to receive IV midazolam in 1-mg increments until they were lightly sedated, fentanyl 2 microg/kg followed by incremental midazolam until they were similarly sedated, or no sedative (n = 20 each). Then, normal saline 3 mL was administered IV, followed 4 min later by 1.5% lidocaine 3 mL plus epinephrine 15 microg (1:200,000) in all subjects. Heart rate (HR), systolic blood pressure (SBP) measured by a radial arterial catheter, and lead II of the electrocardiogram were continuously recorded for 4 min after the saline and test dose injections. An IV test dose produced significant increases in HR and SBP and decreases in T-wave amplitude in all subjects. However, the mean maximum increase in HR in patients sedated with midazolam plus fentanyl (31 +/- 14 bpm [mean +/- SD]) was significantly less than in those administered midazolam alone or no sedative (42 +/- 12 and 44 +/- 10 bpm, respectively; P < 0.05). A sensitivity of 100% was obtained on the basis of the traditional HR criterion (positive if > or =20 bpm increase) in patients sedated with midazolam or no sedative, but it was 70% in those with midazolam plus fentanyl (P < 0.05 versus the other two groups). Irrespective of the treatment, sensitivities and specificities of 100% were obtained according to the SBP (positive if > or =15 mm Hg increase) and T-wave (positive if > or =25% decrease in amplitude) criteria. An increase in SBP and a decrease in T-wave amplitude are more reliable than an HR response for detecting accidental intravascular injection of the epinephrine-containing test dose in subjects sedated with midazolam and fentanyl. ⋯ To determine whether an epidural catheter is in a blood vessel, an epidural test dose containing 15 microg epinephrine is used. We found that an increase in systolic blood pressure and a decrease in T-wave amplitude seem to be more reliable than a heart rate change for detecting inadvertent intravascular injection of an epinephrine-containing test dose in patients sedated with midazolam and fentanyl.
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Anesthesia and analgesia · Dec 2001
Multicenter Study Clinical TrialA dose-determining trial of heparinase-I (Neutralase) for heparin neutralization in coronary artery surgery.
Heparinase-I, a specific heparin-degrading enzyme, may represent an alternative to protamine. We explored the dose of heparinase-I for efficacy and safety in patients undergoing coronary artery surgery. At the conclusion of cardiopulmonary bypass, subjects received 5, 7, or 10 microg/kg of open-label heparinase-I instead of protamine. Activated clotting time (ACT) and its difference from a contemporaneous heparin-free sample (DeltaACT) at 3 min before and 3, 6, and 9 min after heparinase-I determined reversal efficacy. After surgery, we recorded hourly chest tube drainage. Systemic and pulmonary arterial blood pressure and cardiac output measurements before and immediately after heparinase-I were used to evaluate hemodynamic safety. Coagulation measurements included anti-factor Xa and anti-factor IIa activities. Forty-nine patients from seven institutions participated: 12 received 5 microg/kg, 21 received 7 microg/kg, 4 received two doses of 7 microg/kg, 8 received 10 microg/kg, and 4 received two doses of 10 microg/kg. Treatment groups did not differ demographically. Median DeltaACT 9 min later was 11, 7, and 4 s for the 5, 7, and 10 microg/kg groups, respectively. No adverse hemodynamic changes occurred with heparinase-I administration. The authors conclude that heparinase-I effectively restored the ACT after cardiopulmonary bypass. This effect appeared to be dose dependent. ⋯ Heparinase-I (Neutralase(TM)) successfully restored activated coagulation time with no adverse hemodynamic events in patients undergoing coronary artery surgery with cardiopulmonary bypass in an open-label dose-determining trial.
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Anesthesia and analgesia · Dec 2001
Multicenter StudyPharmacokinetics of remifentanil in anesthetized pediatric patients undergoing elective surgery or diagnostic procedures.
Remifentanil hydrochloride is an ultra-short-acting opioid that undergoes rapid metabolism by tissue and plasma esterases. We aimed to characterize the pharmacokinetics and determine the hemodynamic profile of remifentanil after a single-bolus dose in children aged 0 to 18 yr. Forty-two children undergoing elective surgical procedures received remifentanil 5 microg/kg infused over 1 min. Patients were divided into age groups as follows: young infants (< or =2 mo), older infants (> 2 mo to < 2 yr), young children (2 to < 7 yr), older children (7 to < 13 yr), adolescents (13 to < 16 yr), and young adults (16 to < 18 yr). Arterial blood samples were collected and analyzed by mass spectroscopy to determine remifentanil pharmacokinetic profiles. Hemodynamic measurements for remifentanil's effect were made after the infusion. Methods of statistical analysis included analysis of variance and linear regression, with significance at P < or = 0.05. Complete remifentanil pharmacokinetic data were obtained from 34 patients. The volume of distribution was largest in the infants < 2 mo (mean, 452 mL/kg) and decreased to means of 223 to 308 mL/kg in the older patients. There was a more rapid clearance in the infants < 2 mo of age (90 mL. kg(-1). min(-1)) and infants 2 mo to 2 yr (92 mL. kg(-1). min(-1)) than in the other groups (means, 46 to 76 mL. kg(-1). min(-1)). The half-life was similar in all age groups, with means of 3.4 to 5.7 min. Seven subjects (17%) developed hypotension related to the remifentanil bolus. Remifentanil showed an extremely rapid elimination similar to that in adults. The fast clearance rates observed in neonates and infants, as well as the lack of age-related changes in half-life, are in sharp contrast to the pharmacokinetic profile of other opioids. Remifentanil in a bolus dose of 5 microg/kg may cause hypotension in anesthetized children. ⋯ The pharmacokinetics of remifentanil were studied in children from birth to 18 yr. Remifentanil was found to have age-related changes in clearance and volume of distribution, but not half-life. The increased clearance observed in young infants is in contrast to other opioids.
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Anesthesia and analgesia · Dec 2001
Randomized Controlled Trial Clinical TrialThe safety of immediate extubation after abdominal aortic surgery: a prospective, randomized trial.
We performed this study to assess the safety of immediate extubation after elective abdominal aortic aneurysm surgery. Consecutive patients were prospectively randomized into two groups after surgery: Group 1 (n = 29) immediate extubation; and Group 2 (n = 21) delayed (at least 4 h) extubation. All patients were assessed by a senior anesthesiologist or intensivist before extubation. The following data were collected: preoperative-demographics, presence of comorbid disease, body mass index, hemoglobin level, heart rate, and blood pressure; intraoperative-duration of surgery and cross-clamping, blood loss, amount of crystalloids, colloids, and blood transfused, temperature at end of procedure, urine output, and complications; and postoperative-time to extubation, scores on the Acute Physiology and Chronic Health Evaluation-II and Therapeutic Intervention Scoring System, total fentanyl dose, and complications. Outcome variables were length of intensive care unit and hospital stay and 28-day mortality. The results showed no significant differences in preoperative or intraoperative variables between the groups, apart from a longer duration of surgery in Group 1 (P = 0.045). Group 2 patients had a significantly higher Therapeutic Intervention Scoring System score (P = 0.04) and required a significantly larger dose of fentanyl (P < 0.001). One patient in Group 2 required reintubation after a cerebrovascular accident. The overall mortality rate was 4% (2 patients in Group 2). There were no significant differences in any of the outcome variables. We conclude that immediate extubation can safely be performed after elective abdominal aortic aneurysm surgery. ⋯ In this prospective randomized study, we compared the outcome of patients undergoing elective aortic abdominal surgery who either were extubated immediately after surgery or after 4 h of stabilization in the intensive care unit. No significant differences were found in the length of intensive care unit or hospital stay, or 28-day mortality between the 2 groups.
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Anesthesia and analgesia · Dec 2001
Randomized Controlled Trial Comparative Study Clinical TrialSelective spinal anesthesia: a comparison of hyperbaric bupivacaine 4 mg versus 6 mg for outpatient knee arthroscopy.
A low-dose (4 mg), low-volume (0.8 mL), low-flow (2 min) technique with hyperbaric bupivacaine toward the dependent side oriented injection and maintenance of the lateral decubitus position for 10 min produced selective spinal anesthesia with rapid recession of motor block and early discharge home.