Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialSmart technology improves patient-controlled analgesia: a preliminary report.
A new adaptive system has been designed to improve patient-controlled analgesia through the use of a variable bolus dose and a variable background infusion of analgesic. A novel hand set allows patients to rate their own pain on a linear scale of 1 to 10. Data derived from the hand set signals are used by an expert algorithm to repeatedly adapt the drug dosage of the bolus and of the background infusion according to both current pain intensity and the patient's response to previous dosage. To test the system, we performed a small pilot clinical study, using a randomized, double-blinded, cross-over design. The new system was alternated with a conventional system every 12 h. Use of the new system was associated with significantly lower pain scores and fewer bolus requests but more analgesic administration, though without increased adverse effects. It was very well accepted by both patients and clinical staff. ⋯ Pain relief after surgery is often best provided by patient-controlled analgesia, which uses an IV infusion pump and a patient-activated switch. We have developed a new computer-controlled or "smart" patient-controlled analgesia that rapidly learns a patient's individual needs and provides continuously tailored pain relief.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Comparative Study Clinical TrialInhaled nitric oxide versus intravenous vasodilators in severe pulmonary hypertension after cardiac surgery.
Inhaled nitric oxide (iNO) is superior to i.v. vasodilators for treatment of pulmonary hypertension (PH) after cardiac surgery, but iNO is a potentially toxic gas, and patient subsets who benefit from iNO are not yet clearly defined. We administered iNO 40 ppm, prostaglandin E1 (PGE1) 0.1 microg x kg(-1) min(-1), and nitroglycerin (NTG) 3 to 5 microg x kg(-1) min(-1), in a randomized crossover study to 14 adult patients with severe PH after cardiac surgery. iNO, PGE1, and NTG were of similar efficacy in reducing pulmonary vascular resistance (P = 0.003). iNO induced selective pulmonary vasodilation, while PGE1 and NTG had significant concomitant systemic vasodilatory effects. iNO led to an increase in cardiac index (CI) (P = 0.012), and PGE1 increased CI (P = 0.006) and right ventricular (RV) ejection fraction (P = 0.015), while NTG had no effect on CI and RV performance. After study completion, patients continued with PGE1 administration with favorable in-hospital outcome. We conclude that PH per se, even if severe, does not necessarily imply postoperative RV dysfunction, and selective pulmonary vasodilation with iNO may not be superior to PGE1 with regard to CI and RV performance. ⋯ In a prospective, randomized crossover study of inhaled nitric oxide (iNO) versus IV vasodilators, performed in adult patients with severe pulmonary hypertension but preserved right ventricular function after cardiac surgery, iNO was not superior to IV prostaglandin E1 with regard to cardiac index and right ventricular performance. Considering the potential toxicity of iNO, better definition of patient subsets with a positive benefit/risk ratio is warranted.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialExpression of genes for proinflammatory cytokines in alveolar macrophages during propofol and isoflurane anesthesia.
Anesthesia and surgery induce macrophage aggregation and neutrophil influx, responses that characterize an inflammatory reaction in the distal airway. We thus evaluated the time-dependent expression of genes for proinflammatory cytokines during propofol and isoflurane anesthesia. We studied patients anesthetized with propofol (n = 20) or isoflurane (n = 20). Alveolar macrophages were harvested by bronchoalveolar lavage immediately, 2, 4, and 6 h after induction of anesthesia, and at the end of surgery. RNA was extracted from harvested cells and cDNA was synthesized by reverse transcription. Expression of interleukin-1beta (IL-1beta), IL-6, IL-8, interferon gamma, and tumor necrosis factor-alpha was measured by semiquantitative polymerase chain reaction using beta-actin as an internal standard. We observed two 10-fold increases in gene expression of all proinflammatory cytokines except IL-6. The increases in IL-8 and interferon gamma were 1.5-3 times greater during isoflurane than propofol anesthesia. Expression of the genes for IL-1beta and tumor necrosis factor-alpha was similar with each anesthetic. Our data thus indicate that the pulmonary inflammatory response accompanying anesthesia and surgery is accompanied by the expression of proinflammatory cytokines, and that this expression was in some cases greater during isoflurane than propofol anesthesia. ⋯ Gene expression of proinflammatory cytokines in alveolar macrophages increased significantly over time. The increases were greater during isoflurane than propofol anesthesia, suggesting that inflammatory responses at transcriptional levels in alveolar macrophages are modulated by the type and duration of anesthesia.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialAttempting to maintain normoglycemia during cardiopulmonary bypass with insulin may initiate postoperative hypoglycemia.
We attempted to develop an insulin administration protocol that maintains normoglycemia in patients undergoing cardiac surgery and to study the effects of intraoperative blood glucose management on serum levels of creatine phosphokinase isoenzyme BB (CK-BB) and S-100 protein. Twenty nondiabetic patients were randomly allocated to receive either "tight control" of blood glucose with a standardized IV insulin infusion intraoperatively (Group TC) or "no control" of blood glucose intraoperatively (Group NC). Perioperative serum levels of glucose, CK-BB, and S-100 protein were determined in all patients. Group TC patients received 90.0 +/- 49.2 units of insulin, whereas Group NC patients received none. Despite insulin, both Group TC (P = 0.00026) and Group NC (P = 0.00003) experienced similar significant increases in blood glucose levels during hypothermic cardiopulmonary bypass. However, mean blood glucose level upon intensive care unit arrival was significantly decreased in Group TC, compared with Group NC (84.7 +/- 41.0 mg/dL, range 32-137 mg/dL vs 201.4 +/- 67.5 mg/dL, range 82-277 mg/dL, respectively; P = 0.0002). Forty percent of Group TC patients required treatment for postoperative hypoglycemia (blood glucose level <60 mg/dL). Substantial interindividual variability existed in regard to insulin resistance. The investigation was terminated after we realized that normoglycemia was unattainable with the study protocol and that postoperative hypoglycemia was unpredictable. All patients in both groups experienced similar significant increases in postoperative serum levels of CK-BB and S-100 protein. These results indicate that "tight control" of intraoperative blood glucose in nondiabetic patients undergoing cardiac surgery was unattainable with the study protocol and may initiate postoperative hypoglycemia. ⋯ The appropriate intraoperative management of hyperglycemia and whether it adversely affects neurologic outcome in patients after cardiac surgery remains controversial. This investigation reveals that attempting to maintain normoglycemia in this setting with insulin may initiate postoperative hypoglycemia.
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Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Clinical TrialDose response relationships for isobaric spinal mepivacaine using the combined spinal epidural technique.
Mepivacaine, a local anesthetic with similar physiochemical properties to those of lidocaine, is an adequate alternative for patients undergoing ambulatory procedures, and is associated with a lower incidence of transient neurologic symptoms (TNS) than lidocaine. We studied the dose-response characteristics of isobaric intrathecal mepivacaine using the combined spinal epidural technique for patients undergoing ambulatory arthroscopic surgery of the knee. Seventy-five patients were randomized prospectively to receive one of three doses of isobaric mepivacaine for spinal anesthesia: 30 mg (2 mL 1.5%), 45 mg (3 mL 1.5%), or 60 mg (4 mL 1.5%). An observer, blinded to the dose, recorded sensory level to pinprick and motor response until resolution of the block. In addition, the incidence of TNS was determined. An initial intrathecal dose of 30 mg of isobaric mepivacaine 1.5% produced satisfactory anesthesia in 72% of ambulatory surgical patients undergoing unilateral knee arthroscopy with a significantly shorter duration of sensory (158 +/- 32 min) and motor blockade (116 +/- 38 min) than doses of 45 and 60 mg. An intrathecal dose of 45 mg produced satisfactory anesthesia in all patients with a shorter duration of sensory (182 +/-38 min) and motor blockade (142 +/- 37 min) than 60 mg of mepivacaine 1.5% (203 +/- 36 min and 168 +/- 36 min, respectively). The incidence of TNS was 7.4% overall (1.2%-13.6% confidence intervals), less than the rates previously reported after spinal anesthesia with lidocaine in ambulatory surgical patients undergoing knee arthroscopy. We conclude that mepivacaine can be used as an adequate alternative to lidocaine for ambulatory procedures. ⋯ This study evaluated the postoperative duration of spinal anesthesia after varying doses of isobaric mepivacaine and the incidence of transient radiating back and leg pain. We found that 45 mg of mepivacaine provided adequate anesthesia, a timely discharge, and a lower incidence of back pain than that previously reported after lidocaine spinals.