Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2001
Randomized Controlled Trial Clinical TrialThe dose-response relationship for clonidine added to a postoperative continuous epidural infusion of ropivacaine in children.
Epidurally administered clonidine enhances the quality and duration of postoperative analgesia when it is used as an adjunct to local anesthetics in children. We investigated the dose-response relationship for epidural clonidine when added to a continuous postoperative epidural infusion of ropivacaine. By use of an observer-blinded design, 55 pediatric patients (1-4 yr old) were randomly given a postoperative epidural infusion of plain ropivacaine 0.1% 0.2 mg. kg(-1). h(-1) (Group R), ropivacaine 0.08% 0.16 mg. kg(-1). h(-1) plus clonidine 0.04 microg. kg(-1). h(-1) (Group RC1), ropivacaine 0.08% 0.16 mg. kg(-1). h(-1) plus clonidine 0.08 microg. kg(-1). h(-1) (Group RC2), or ropivacaine 0.08% 0.16 mg. kg(-1). h(-1) plus clonidine 0.12 microg. kg(-1). h(-1) (Group RC3). A clear dose-response relationship could be identified for a continuous infusion of epidural clonidine, with clonidine dosages in the 0.08-0.12 microg. kg(-1). h(-1) range providing improved postoperative analgesia (reduced Children's Hospital of Eastern Ontario pain score, increased time to first supplemental analgesic demand, and a reduced total number of doses of supplemental analgesics during the first 48 h after surgery). Analgesia was improved without any signs of increased sedation or other side effects. The adjunct use of epidural clonidine in the dosage range of 0.08-0.12 microg. kg(-1). h(-1) appears effective and safe for use in children. ⋯ The addition of clonidine (0.08-0.12 microg.kg(-1).h(-1))to a continuous epidural infusion of ropivacaine was found to improve postoperative pain relief in children. No clinically significant signs of sedation or other side effects were observed.
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Anesthesia and analgesia · Jul 2001
Biography Historical ArticlePioneers in epidural needle design.
In this article we discuss the development of epidural needles and the historical factors leading to their invention. The most popular needles are described and their inventors acknowledged.
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Anesthesia and analgesia · Jul 2001
The accuracy of coagulation tests during spinal fusion and instrumentation.
Patients undergoing major spine surgery may acquire a perioperative coagulopathy from dilution of coagulation factors and/or platelets or fibrinolysis. The mechanisms of the coagulopathy and role of coagulation testing during these procedures are poorly defined. Theoretically, coagulation tests could be used perioperatively to determine which patients are at risk for significant bleeding and guide transfusion therapy. We retrospectively evaluated the sensitivity, specificity, and accuracy of coagulation tests in predicting excessive surgical bleeding in 244 consecutive patients undergoing thoracic, lumbar, or sacral spinal fusion with or without instrumentation. Excessive bleeding was reported by the surgeon in 39 of the patients and was defined as recurrent microvascular bleeding despite adequate use of electrocautery and suture or decreased clot formation of blood pooled within the surgical field. Patients with excessive clinical bleeding sustained larger estimated blood losses than those with normal hemostasis. The total number of allogeneic red blood cells, platelets, and fresh frozen plasma units were also larger in patients with excessive bleeding noted during surgery. The intraoperative coagulation tests with the most sensitivity and specificity were the international normalized ratio (INR), prothrombin time (PT), and activated partial thromboplastin time (aPTT). The INR had a sensitivity of 94%, a specificity of 88%, and an accuracy of 0.9 at a value of 1.4 (normal, 0.8-1.2). The PT had a sensitivity of 90%, a specificity of 64%, and an accuracy of 0.73 at a value of 13.5 s (normal, 8.4-12.0 s). The aPTT had a sensitivity of 85%, a specificity of 64%, and an accuracy of 0.71 at a value of 30.9 s (normal, 23-37 s). The thromboelastogram values were of marginal use. We conclude that the INR, PT, and aPTT may be helpful in guiding transfusion therapy in patients undergoing major spine surgery. ⋯ Patients undergoing major surgery to the spine often acquire a perioperative coagulopathy. The prothrombin time and activated partial thromboplastin time had the greatest sensitivity and specificity for predicting bleeding in major surgery of the spine. The test values that differentiated normal from excessively bleeding patients could be used to guide transfusion therapy during surgery.
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Anesthesia and analgesia · Jul 2001
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of single or multiple injections on the volume of 0.5% ropivacaine required for femoral nerve blockade.
We compared the effects of using a single- or multiple-injection technique on the volume of 0.5% ropivacaine required to block the femoral nerve, in a prospective, randomized, blinded fashion in which 50 premedicated patients received a femoral nerve block with 0.5% ropivacaine by use of a nerve stimulator and either a single- (n = 25) or multiple- (n = 25) injection technique. Muscular twitches were elicited at < or =0.5 mA before anesthetic injection. The designated volume of local anesthetic was equally divided among contraction of the vastus medialis, vastus intermedius, and vastus lateralis for the multiple injections, or it was injected at the contraction of the vastus intermedius with motion of the patella for the single injection. The local anesthetic volumes were varied for consecutive patients by using an up-and-down staircase method; a blinded observer determined the adequacy of nerve blockade (loss of pinprick sensation in the medial, patellar, and lateral portions of the knee, with concomitant block of the quadriceps muscle) 20 min after injection. The mean (95% confidence interval) volume required for blocking the femoral nerve with the multiple-injection technique (14 [12-16] mL) was significantly smaller than that observed with the single injection (23 [20-26] mL) (P = 0.001). According to logistic regression analyses, the 95% effective volumes of ropivacaine required to block the femoral nerve within 20 min after injection were 29 and 21 mL with a single or multiple injection, respectively. We conclude that searching for multiple muscular twitches reduces the volume of 0.5% ropivacaine required to produce blockade of the femoral nerve. ⋯ We evaluated the effects of using a single- or multiple-injection technique on the volume of 0.5% ropivacaine required to block the femoral nerve. The 95%effective concentration values for producing the same degree of sensory and motor blockade of the femoral nerve within 20 min after injection were 29 mL after elicitation of a patella twitch and 21 mL when the three main branches of the femoral nerve were identified, potentially leading to an important benefit for patients receiving peripheral nerve blocks.
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Anesthesia and analgesia · Jul 2001
Randomized Controlled Trial Clinical TrialThe clinical and biochemical effects of propofol infusion with and without EDTA for maintenance anesthesia in healthy children undergoing ambulatory surgery.
We conducted this randomized, double-blinded, comparative, parallel-group study to determine whether adding EDTA to propofol would affect the clinical profile, calcium and magnesium homeostasis, or renal function in healthy children. After the induction of anesthesia with halothane, 69 ambulatory surgical patients (1 mo to <17 yr old), received propofol without EDTA (n = 33) or propofol with EDTA (n = 36). Blood samples were obtained for the measurement of ionized calcium, ionized magnesium, and laboratory indicators of renal function. Hemodynamic measurements, recovery, and adverse events were recorded. Propofol with EDTA produced no significant effects on clinical efficacy or renal function. Propofol and propofol EDTA produced a statistically significant decrease from baseline in serum concentrations of ionized calcium and magnesium during infusion (P<0.05), but with no apparent clinical effect. Hemodynamic measurements generally remained stable and were similar for both groups. Statistically significant changes in systolic blood pressure, mean arterial pressure, and heart rate were not considered clinically significant. Adverse events were mild or moderate. The addition of EDTA does not alter the clinical profile of propofol in pediatric ambulatory surgical patients. With or without EDTA, propofol is associated with a decrease in ionized calcium with no apparent clinical effect. ⋯ The addition of EDTA does not alter the clinical profile of propofol in pediatric ambulatory surgical patients. With or without EDTA, propofol is associated with a decrease in ionized calcium with no apparent clinical effect.