Anesthesia and analgesia
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialHigh thoracic epidural anesthesia, but not clonidine, attenuates the perioperative stress response via sympatholysis and reduces the release of troponin T in patients undergoing coronary artery bypass grafting.
In this prospective study, we evaluated whether high thoracic epidural anesthesia (TEA) or i.v. clonidine, in addition to general anesthesia, affects the cardiopulmonary bypass- and surgery-associated stress response and incidence of myocardial ischemia by their sympatholytic properties. Seventy patients scheduled for elective coronary artery bypass graft (CABG) received general anesthesia with sufentanil and propofol. TEA was randomly induced before general anesthesia and continued during the study period in 25 (anesthetized dermatomes C6-T10). Another 24 patients received i.v. clonidine as a bolus of 4 microg/kg before the induction of general anesthesia. Clonidine was then infused at a rate of 1 microg x kg(-1) x h(-1) during surgery and at 0.2-0.5 microg x kg(-1) x h(-1) postoperatively. The remaining 21 patients underwent general anesthesia as performed routinely (control). Hemodynamics, plasma epinephrine and norepinephrine, cortisol, the myocardial-specific contractile protein troponin T, and other cardiac enzymes were measured pre- and postoperatively. During the preoperative night and a follow-up of 48 h after surgery, five-lead electrocardiogram monitoring was used for ischemia detection. Both TEA and clonidine reduced the postoperative heart rate compared with the control group without jeopardizing cardiac output or perfusion pressure. Plasma epinephrine increased perioperatively in all groups but was significantly lower in the TEA group. Neither TEA nor clonidine affected the increase in plasma cortisol. The release of troponin T was attenuated by TEA. New ST elevations > or = 0.2 mV or new ST depression > or = 0.1 mV occurred in > 70% of the control patients but only in 40% of the clonidine group and in 50% of the TEA group. We conclude that TEA (but not i.v. clonidine) combined with general anesthesia for CABG demonstrates a beneficial effect on the perioperative stress response and postoperative myocardial ischemia. ⋯ Thoracic epidural anesthesia combined with general anesthesia attenuates the myocardial sympathetic response to cardiopulmonary bypass and cardiac surgery. This is associated with decreased myocardial ischemia as determined by less release of troponin T. These findings may have an impact on the anesthetic management for coronary artery bypass grafting.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Clinical TrialPostoperative analgesia for outpatient arthroscopic knee surgery with intraarticular clonidine.
Intraarticular (i.a.) local anesthetics are often used for the management and prevention of pain after arthroscopic knee surgery. Clonidine prolongs the duration of local anesthetics. We designed this study to determine whether clonidine added to an i.a. injection would result in an analgesic benefit. Fifty patients were randomly assigned to one of five groups that received clonidine (either via the subcutaneous or i.a. route) or saline placebo with or without i.a. bupivacaine, as follows: Group 1 received 30 mL of 0.25% bupivacaine i.a.; Group 2 received 30 mL of 0.25% bupivacaine with clonidine (1 microg/kg) i.a.; Group 3 received 30 mL of 0.25% bupivacaine i.a. and subcutaneous clonidine (1 microg/kg); Group 4 received 30 mL of 0.25% bupivacaine with epinephrine (5 microg/mL) i.a.; and Group 5 received clonidine (1 microg/kg) in 30 mL of saline i.a.. The results of this study revealed a significant difference in analgesia from the i.a. administration of clonidine. The group who received a combination of i.a. bupivacaine and clonidine had a significantly decreased need for oral postoperative analgesics and an increased analgesic duration (P < 0.0001). We conclude that i.a. clonidine improved comfort in patients undergoing knee arthroscopy. ⋯ The intraarticular administration of clonidine along with bupivacaine results in a significant improvement in analgesia compared with either drug alone. There was an increased time to first analgesic request and a decreased need for postoperative analgesics.
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Anesthesia and analgesia · Apr 1999
Multicenter Study Clinical TrialNerve stimulator and multiple injection technique for upper and lower limb blockade: failure rate, patient acceptance, and neurologic complications. Study Group on Regional Anesthesia.
To evaluate the failure rate, patient acceptance, effective volumes of local anesthetic solution, and incidence of neurologic complications after peripheral nerve block performed using the multiple injection technique with a nerve stimulator, we prospectively studied 3996 patients undergoing combined sciatic-femoral nerve block (n = 2175), axillary blocks (n = 1650), and interscalene blocks (n = 171). The success rate and mean injected volumes of local anesthetic were: 93% with 22.6 +/- 4.5 mL in the axillary, 94% with 24.5 +/- 5.4 mL in the interscalene, and 93% with 28.1 +/- 4.4 mL in the sciatic-femoral nerve blocks. Patients receiving combined sciatic-femoral nerve block showed more discomfort during block placement and worse acceptance of the anesthetic procedure than patients receiving brachial plexus anesthesia. During the first month after surgery, 69 patients (1.7%) developed neurologic dysfunction on the operated limb. Complete recovery required 4-12 wk in all patients but one, who required 25 wk. The only variable showing significant association with the development of postoperative neurologic dysfunction was the tourniquet inflation pressure (<400 mm Hg compared with >400 mm Hg, odds ratio 2.9, 95% confidence intervals 1.6-5.4; P < 0.001). We conclude that using the multiple injections technique with a nerve stimulator results in a success rate of >90% with a volume of <30 mL of local anesthetic solution and an incidence of transient neurologic complication of <2%. ⋯ Based on a prospective evaluation of 3996 consecutive peripheral nerve blocks, the multiple injection technique with nerve stimulator allows for up to 94% successful nerve block with <30 mL of local anesthetic solution. Although the data collection regarding neurologic dysfunction was limited, the withdrawal and redirection of the stimulating needle was not associated with an increased incidence of neurologic complications. Sedation/analgesia should be advocated during block placement to improve patient acceptance.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of stimulus frequency on the analgesic response to percutaneous electrical nerve stimulation in patients with chronic low back pain.
Low back pain (LBP) is one of the most common medical problems in our society. Increasingly, patients are turning to nonpharmacologic analgesic therapies such as percutaneous electrical nerve stimulation (PENS). We designed this sham-controlled study to compare the effect of three different frequencies of electrical stimulation on the analgesic response to PENS therapy. Sixty-eight consenting patients with LBP secondary to degenerative lumbar disc disease were treated with PENS therapy at 4 Hz, alternating 15 Hz and 30 Hz (15/30 Hz), and 100 Hz, as well as sham-PENS (0 Hz), according to a randomized, cross-over study design. Each treatment was administered for a period of 30 min three times per week for 2 wk. The pre- and posttreatment assessments included the health status survey short form and visual analog scales for pain, physical activity, and quality of sleep. After receiving all four treatments, patients completed a global assessment questionnaire. The sham-PENS treatments failed to produce changes in the degree of pain, physical activity, sleep quality, or daily intake of oral analgesic medications. In contrast, 4-Hz, 15/30-Hz, and 100-Hz stimulation all produced significant decreases in the severity of pain, increases in physical activity, improvements in the quality of sleep, and decreases in oral analgesic requirements (P < 0.01). Of the three frequencies, 15/30 Hz was the most effective in decreasing pain, increasing physical activity, and improving the quality of sleep (P < 0.05). In the global assessment, 40% of the patients reported that 15/30 Hz was the most desirable therapy, and it was also more effective in improving the patient's sense of well-being. We conclude that the frequency of electrical stimulation is an important determinant of the analgesic response to PENS therapy. Alternating stimulation at 15-Hz and 30-Hz frequencies was more effective than either 4 Hz or 100 Hz in improving outcome measures in patients with LBP. ⋯ The frequency of electrical stimulation seems to be an important determinant of the analgesic efficacy of percutaneous electrical nerve stimulation. Mixed low- and high-frequency stimulation was more effective than either low or high frequencies alone in the treatment of patients with low back pain.
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Anesthesia and analgesia · Apr 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe cost-effectiveness of methohexital versus propofol for sedation during monitored anesthesia care.
We designed this study to test the hypothesis that methohexital is a cost-effective alternative to propofol for sedation during local anesthesia. Sixty consenting women undergoing breast biopsy procedures under local anesthesia were randomly assigned to receive an infusion of either propofol (50 microg x kg(-1) x min(-1)) or methohexital (40 microg x kg(-1) x min(-1)). The sedative infusion rate was titrated to maintain an observer's assessment of alertness/sedation (OAA/S) score of 3 (with 1 = awake/alert to 5 = asleep). Fentanyl 25 microg i.v. was administered as a "rescue" analgesic during the operation. We assessed the level of sedation (OAA/S score), vital signs, time to achieve an OAA/S score of 3 at the onset and a score of 1 after discontinuing the infusion, discharge times, perioperative side effects, and patient satisfaction. The direct cost of methohexital was lower than that of propofol, based on the milligram dosage infused during the operation. The sedative onset (to achieve an OAA/S score of 3) and the recovery (to return to an OAA/S score of 1) times, as well as discharge times, did not differ between the two groups. Patients receiving methohexital had a significantly lower incidence of pain on initial injection compared with those receiving propofol (10% vs 23%). Because the use of methohexital (29.4 +/- 2.7 microg x kg(-1) x min(-1)) for sedation during breast biopsy procedures has a similar efficacy and recovery profile to that of propofol (36.8 +/- 15.9 microg x kg(-1) x min(-1)) and is less costly based on the amount infused, it seems to be a cost-effective alternative to propofol for sedation during local anesthesia. However, when the cost of the drug infused and drug wasted was calculated, there was no difference in the overall drug cost. ⋯ When administered to maintain a stable level of sedation during local anesthesia, methohexital is an acceptable alternative to propofol. However, the overall drug costs were similar with the two drugs.