Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2003
Postcardiac surgery complications: association of acute renal dysfunction and atrial fibrillation.
Postoperative creatinine increase is associated with adverse outcome after cardiac surgery. Although postoperative stroke and renal dysfunction are associated after cardiac surgery, suggesting a common systemic insult, a similar assessment of atrial fibrillation and renal dysfunction has not been performed. Therefore, we tested the hypothesis that patients with new-onset atrial fibrillation complicating coronary bypass surgery have a greater postoperative creatinine increase. Data were obtained for 453 elective coronary bypass surgery patients with no history of atrial fibrillation. Multivariate regression analyses of factors associated with peak fractional change in creatinine demonstrated a two-way interaction between age and atrial fibrillation (variable estimate, -1.1; P = 0.002). Similar results were obtained in a secondary multivariate model analyzing factors associated with peak postoperative creatinine (variable estimate, -0.01; P = 0.04). We confirmed our hypothesis that patients with new-onset atrial fibrillation are more likely to have acute renal dysfunction after cardiac surgery. The association of atrial fibrillation and creatinine increase diminishes with advancing age. These data are consistent with a common pathophysiology that contributes in an age-dependent fashion to the etiology of both acute renal dysfunction and atrial fibrillation after coronary bypass surgery. ⋯ We found an independent association between new-onset atrial fibrillation and postoperative creatinine increase that is influenced by age. The degree to which atrial fibrillation is associated with postoperative creatinine increase diminishes with advancing age. This interaction suggests that a common etiology for these two complications may be more important in younger patients.
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Anesthesia and analgesia · Mar 2003
Randomized Controlled Trial Clinical TrialA single small dose of postoperative ketamine provides rapid and sustained improvement in morphine analgesia in the presence of morphine-resistant pain.
It is a common clinical observation that postoperative pain may be resistant to morphine. The analgesic potentials of ketamine have also been well documented. In this study, we evaluated the effects of postoperative coadministration of small doses of ketamine and morphine on pain intensity, SpO(2), and subjectively rated variables in surgical patients who underwent standardized general anesthesia and complained of pain (> or =6 of 10 on a visual analog scale [VAS]) despite >0.1 mg/kg of i.v. morphine administration within 30 min. Patients randomly received up to three boluses of 30 microg/kg of morphine plus saline (MS; n = 114) or 15 microg/kg of morphine plus 250 microg/kg of ketamine (MK; n = 131) within 10 min in a double-blinded manner. The MS group's pain VAS scores were 5.5 +/- 1.18 and 3.8 +/- 0.9 after 10 and 120 min, respectively, after 2.52 +/- 0.56 injections, versus the MK group's VAS scores of 2.94 +/- 1.28 and 1.47 +/- 0.65, respectively (P < 0.001), after 1.35 +/- 0.56 injections (P < 0.001). The 10-min level of wakefulness (1-10 VAS) in the MS group was significantly (P < 0.001) less (6.1 +/- 1.5) than the MK group's (8.37 +/- 1.19). SpO(2) decreased by 0.26% in the MS group but increased by 1.71% in the MK patients at the 10-min time point (P < 0.001). Thirty MS versus nine MK patients (P < 0.001) experienced nausea/vomiting; nine MK patients sustained a 2-min light-headed sensation, and one patient had a weird dream after the second drug injection. ⋯ A small-dose ketamine and morphine regimen interrupted severe postoperative pain that was not relieved previously by morphine. Ketamine reduced morphine consumption and provided rapid and sustained improvement in morphine analgesia and in subjective feelings of well-being, without unacceptable side effects.
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Anesthesia and analgesia · Mar 2003
Continuous intrathecal clonidine and tizanidine in conscious dogs: analgesic and hemodynamic effects.
Alpha-2-adrenergic agonists, such as clonidine, produce antinociception in animal pain models after intrathecal administration. However, clinical usage is limited by cardiovascular side effects. To investigate alternative alpha(2)-adrenergic agonists as analgesics, we implanted six dogs with an intrathecal catheter and infusion pump. After baseline saline infusion, animals received clonidine or tizanidine (crossover study) each week at escalating doses of 125-750 microg/h. Analgesia, blood pressure, heart rate, respiratory rate, sedation, and coordination were evaluated. A 28-day safety study was performed with another nine dogs receiving intrathecal tizanidine (3 or 6 mg/d) or saline. Equal doses of clonidine and tizanidine produce the same antinociception in thermal withdrawal tests. Blood pressure was reduced with 125-500 microg/h of clonidine, but not with tizanidine at any dose. Clonidine 250 microg/h reduced heart rate by 45.8%, and five of six animals had bradyarrhythmias (marked bradycardia), whereas tizanidine decreased heart rate by 15.1% without arrhythmias, even at the largest dose. Respiratory rate decreased with 250 microg/h of clonidine and larger doses. Sedation or incoordination occurred only at the largest dose for either drug. The safety study indicated that 3 mg/d of tizanidine in dogs produced no side effects or histopathologic changes. Tizanidine may be a useful alternative in patients experiencing cardiovascular side effects with intrathecal infusion of clonidine. ⋯ Clonidine is an effective spinal analgesic, but it is dose-limited by cardiovascular side effects. We compared the analgesic properties and side effects of clonidine with those of a similar drug, tizanidine. Continuous spinal infusion of tizanidine produced similar analgesia as clonidine, but with fewer adverse effects on blood pressure and heart rate.
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Anesthesia and analgesia · Mar 2003
Clinical TrialInfragluteal-parabiceps sciatic nerve block: an evaluation of a novel approach using a single-injection technique.
Clinical use of the sciatic nerve block (SNB) has been limited by technical difficulties in performing the block using standard approaches, substantial patient discomfort during the procedure, or the need for two injections to block the tibial and peroneal nerves. In this report, we describe a single-injection method for SNB using an infragluteal-parabiceps approach, where the nerve is located along the lateral border of the biceps femoris muscle. SNB was performed in the prone or lateral decubitus position. The needle was positioned (average depth, 56 +/- 15 mm) to the point where plantar flexion (53%) or inversion (45%) of the ipsilateral foot was obtained at < or =0.4 mA. Levobupivacaine 0.625% with epinephrine (1:200:000) was administered at a dose of 0.4 mL/kg. The procedure was completed in 6 +/- 3 min. Discomfort during block placement was treated with fentanyl 50-100 microg in 24% of patients. Complete sensory loss and motor paralysis occurred in 92% of subjects at a median time of 10 (range, 5-25) min after injection. Compared with plantar flexion, foot inversion was associated with a more frequent incidence (86% versus 100%), and shorter latency for both sensory loss and motor paralysis of the peroneal, tibial, and sural nerves. There were no immediate or delayed complications. We conclude that the infragluteal-parabiceps approach to SNB is reliable, efficient, safe, and well tolerated by patients. ⋯ Sciatic nerve block using the infragluteal-parabiceps approach produces sensory loss and motor paralysis after a single 0.4 mL/kg injection of levobupivacaine 0.625% with epinephrine (1:200,000) in >90% of patients. The approach is reliable, uses consistent soft-tissue landmarks, is not typically painful, and does not produce significant complications.
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Anesthesia and analgesia · Mar 2003
Inclusion of turnover time does not influence identification of surgical services that over- and underutilize allocated block time.
Allocation of operating room (OR) block time is an ongoing challenge for OR managers. In this study, we sought to determine whether inclusion or exclusion of turnover time in comparisons of block utilization would identify different surgical services as under- or overused. For a 13-mo period, we evaluated data extracted from the OR information system of a large academic medical center. During that time period, 15 surgical services performed 12,245 surgical procedures. Allocated block hours, number of first cases performed, total number of cases, and average case durations were determined. The average turnover time for each service was determined by a manual, case-by-case review of data from 1 mo. Raw utilization (RU; case durations only) and adjusted utilization (AU; case duration plus turnover time) were calculated for each service. Turnover time was credited to the service performing surgery after room turnover. Case du-ration was limited to surgeries performed during resource hours. Two indices of utilization (i.e., the usage rate of the service divided by the overall use of all ORs in the suite) were used to compare services: the RU or AU Index (RUI or AUI). Outliers were services with indices that were >1.15 or <0.85. The RUI identified three services as underutilizers and one service as an overutilizer. Using the AUI, the same outliers were identified, and no new services were identified. Examining the changes in index (between AUI and RUI), the percentage of to-follow cases highly correlated with changes in index (r(2) = 0.60); the average turnover time did not (r(2) = 0.002). Inclusion of turnover time did not change the services that were identified as under- and overutilizer. ⋯ Turnover time is difficult to determine from existing operating room information systems. This study determined the use of block time with and without turnover time for each surgical service in a large academic hospital. Turnover time did not change identification of surgical services that over- (one service) or underused (three services) allocated block time.