Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2003
ReviewKetamine in chronic pain management: an evidence-based review.
Ketamine has diverse effects that may be of relevance to chronic pain including: N-methyl-D-aspartic acid, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, gamma-aminobutyric acid(A) receptors; inhibition of voltage gated Na(+) and K(+) channels and serotonin, dopamine re-uptake. Ketamine has been in clinical practice for over 30 yr; however, there has been little formal research on the effectiveness of ketamine for chronic pain management. In this review we evaluate the available clinical data as a basis for defining the potential use of ketamine for chronic pain. ⋯ In conclusion, the evidence for efficacy of ketamine for treatment of chronic pain is moderate to weak. However, in situations where standard analgesic options have failed ketamine is a reasonable "third line" option. Further controlled studies are needed.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialRopivacaine and fentanyl concentrations in patient-controlled epidural analgesia during labor: a volume-range study.
We enrolled nulliparous women in induced labor in a randomized study to determine whether increasing the concentration of the solution used in a patient-controlled epidural analgesia (PCEA) device was required as labor progressed. Patients were assigned to 6 groups (n = 25 in each group), receiving ropivacaine/fentanyl in concentrations of either 0.1%/0.5 microg/mL or 0.2%/1 microg/mL via a PCEA pump. Three groups received boluses of 12, 16, or 20 mL dilute solution in early labor (uterine contractions every 3 min and 4-cm cervical dilation) then 6, 8, and 10 mL concentrated solution in late labor. Three other groups received boluses of 12, 16, or 20 mL dilute solution during both periods. The lockout interval was 25 min. The primary outcome was time until the first request for staff-administered analgesia supplement. Hourly assessments included pain scores on a visual analog scale (VAS) graded from 0 to 10, satisfaction scores, arterial blood pressure, motor block intensity, and the upper sensory level of epidural anesthesia. Patients, midwives, and the observer were unaware of study solutions and PCEA settings. The maximum pain score was defined as the highest score experienced by each patient during each period. Duration of analgesia was defined as the time from the start of each period to the first injection of rescue analgesia and was compared using a survival analysis. There were no differences among the groups with regard to demographic and obstetric variables, arterial blood pressure, motor block intensity, upper sensory level, or satisfaction scores. At least 75% of the women rated their satisfaction as either good or excellent during each period. During late labor, the maximum pain score was lower in the group receiving 20 mL dilute solution compared with the group receiving 6 mL concentrated solution. Maximum pain score was not significantly different between 20 mL dilute solution and 10 mL concentrated solution (difference between VAS values = -0.4; 95% confidence limits, -1.599 and 0.799; P = 0.5055). During late labor, the duration of analgesia was longer in groups receiving 20 mL dilute solution (99 +/- 4 min) (mean +/- SD) than in those receiving 12 mL (77 +/- 30 min) and 16 mL (80 +/- 23 min). Duration of analgesia did not differ between groups receiving 20 mL and 10 mL (92 +/- 23 min) or between groups receiving 12 mL and 6 mL (78 +/- 30 min) of each respective solution. Duration of analgesia was longer in the groups receiving 8 mL concentrated solution (94 +/- 16 min) than in those receiving 16 mL dilute solution. We concluded that 0.1%/0.5 microg/mL ropivacaine/fentanyl was effective throughout labor when 20 mL was injected with each PCEA demand. With 16 mg ropivacaine and 8 microg fentanyl, the duration of analgesia was prolonged by doubling the concentration when labor became active. When 12 mg ropivacaine and 6 microg fentanyl were injected at each demand, analgesia was less satisfactory and doubling the concentration was not clinically effective. These results suggest that the effectiveness of PCEA is dependent on drug mass rather than the volume or concentration administered with each successful pump demand. ⋯ There is no clinical reason for increasing the concentration of the patient-controlled epidural analgesia (PCEA) solution when labor becomes active provided that an effective dose is already being administered with each demand. The quality of PCEA depends on the drug mass given with each demand rather than the concentration of the pump solution.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialPreoperative interscalene block for elective shoulder surgery: loss of benefit over early postoperative block after patient discharge to home.
We performed a randomized, prospective, parallel-group, open-label, multicenter trial to compare the effects of pre- versus postoperative interscalene block using levobupivacaine on postoperative pain and analgesic requirements. One-hundred-two outpatients scheduled for elective shoulder surgery were randomized to receive 30 mL of 0.5% levobupivacaine either preoperatively (PRE group) or postoperatively (POST group). Analgesic outcome measures during the postoperative period were: (a). time to first request for analgesic medication after surgery, (b). pain intensity using the visual analog scale at rest and during arm movement, and (c). total analgesic consumption of nonsteroidal antiinflammatory drugs and opioids. The time to first analgesic request did not differ between treatment groups. However, mean maximum pain intensity scores during the day of surgery were significantly less for the PRE group than the POST group, both at rest (P = 0.001) and after movement (P = 0.004). The mean opioid administered during surgery was lower in the PRE than the POST group (P < 0.001). Levobupivacaine was well tolerated in both treatment groups, and no adverse reactions were related to this local anesthetic. In conclusion, preoperative interscalene block with levobupivacaine provided superior pain control for the first 12 h after surgery, but this benefit was not maintained during the week after discharge because the subjects assumed control of their own pain relief as outpatients. ⋯ Preoperative interscalene block with levobupivacaine provides safe and effective analgesia for same-day elective shoulder surgery, but the benefit of this one-time intervention does not persist.
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Anesthesia and analgesia · Dec 2003
Risk factors for acute lung injury after thoracic surgery for lung cancer.
Acute lung injury (ALI) may complicate thoracic surgery and is a major contributor to postoperative mortality. We analyzed risk factors for ALI in a cohort of 879 consecutive patients who underwent pulmonary resections for non-small cell lung carcinoma. Clinical, anesthetic, surgical, radiological, biochemical, and histopathologic data were prospectively collected. The total incidence of ALI was 4.2% (n = 37). In 10 cases, intercurrent complications (bronchopneumonia, n = 5; bronchopulmonary fistula, n = 2; gastric aspiration, n = 2; thromboembolism, n = 1) triggered the onset of ALI 3 to 12 days after surgery, and this was associated with a 60% mortality rate (secondary ALI). In the remaining 27 patients, no clinical adverse event preceded the development of ALI-0 to 3 days after surgery-that was associated with a 26% mortality rate (primary ALI). Four independent risk factors for primary ALI were identified: high intraoperative ventilatory pressure index (odds ratio, 3.5; 95% confidence interval, 1.7-8.4), excessive fluid infusion (odds ratio, 2.9; 95% confidence interval, 1.9-7.4), pneumonectomy (odds ratio, 2.8; 95% confidence interval, 1.4-6.3), and preoperative alcohol abuse (odds ratio, 1.9; 95% confidence interval, 1.1-4.6). In conclusion, we describe two clinical forms of post-thoracotomy ALI: 1). delayed-onset ALI triggered by intercurrent complications and 2). an early form of ALI amenable to risk-reducing strategies, including preoperative alcohol abstinence, lung-protective ventilatory modes, and limited fluid intake. ⋯ In an observational study including all patients undergoing lung surgery, we describe two clinical forms of acute lung injury (ALI): a delayed-onset form triggered by intercurrent complications and an early form associated with preoperative alcohol consumption, pneumonectomy, high intraoperative pressure index, and excessive fluid intake over the first 24 h.
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Anesthesia and analgesia · Dec 2003
The dose-related effects of ketamine on mortality and cytokine responses to endotoxin-induced shock in rats.
In our previous study, ketamine administration was found to inhibit hypotension, metabolic acidosis, and cytokine responses in endotoxemia. However, only a few studies have indicated whether ketamine has the dose-related beneficial effects after endotoxin injection. Our objective was to clarify the dose-related effects of ketamine on mortality and cytokine responses to endotoxemia in rats. ⋯ Ketamine administration thus clearly had a beneficial effect on mortality rates, with that for group M lower than for groups L and H (P < 0.05). The cytokine responses to endotoxin were somewhat suppressed in group M but not in group L. Ketamine administration dose-independently inhibited hypotension, metabolic acidosis, and cytokine responses in rats injected with endotoxin.