Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1997
Comparative StudyArgon pneumoperitoneum is more dangerous than CO2 pneumoperitoneum during venous gas embolism.
We investigated the possibility of using argon, an inert gas, as a replacement for carbon dioxide (CO2). The tolerance of argon pneumoperitoneum was compared with that of CO2 pneumoperitoneum. Twenty pigs were anesthetized with enflurane 1.5%. Argon (n = 11) or CO2 (n = 9) pneumoperitoneum was created at 15 mm Hg over 20 min, and serial intravenous injections of each gas (ranging from 0.1 to 20 mL/kg) were made. Cardiorespiratory variables were measured. Transesophageal Doppler and capnographic monitoring were assessed in the detection of embolism. During argon pneumoperitoneum, there was no significant change from baseline in arterial pressure and pulmonary excretion of CO2, mean systemic arterial pressure (MAP), mean pulmonary artery pressure (PAP), or systemic and pulmonary vascular resistances, whereas CO2 pneumoperitoneum significantly increased these values (P < 0.05). During the embolic trial and from gas volumes of 2 and 0.2 mL/kg, the decrease in MAP and the increase in PAP were significantly higher with argon than with CO2 (P < 0.05). In contrast to CO2, argon pneumoperitoneum was not associated with significant changes in cardiorespiratory functions. However, argon embolism seems to be more deleterious than CO2 embolism. The possibility of using argon pneumoperitoneum during laparoscopy remains uncertain. ⋯ Laparoscopic surgery requires insufflation of gas into the peritoneal cavity. We compared the hemodynamic effects of argon, an inert gas, and carbon dioxide in a pig model of laparoscopic surgery. We conclude that argon carries a high risk factor in the case of an accidental gas embolism.
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Anesthesia and analgesia · Dec 1997
Transdiscal lumbar sympathetic block: a new technique for a chemical sympathectomy.
Genitofemoral neuritis, which occurs when the neurolytic solution spreads into the psoas muscle, is the most common complication after neurolytic lumbar sympathetic block. We developed a transdiscal approach for neurolytic lumbar sympathetic block to reduce the danger of genitofemoral neuritis by making a sympathectomy without penetration of the psoas muscle, through which the genitofemoral nerve passes. We attempted transdiscal lumbar sympathetic block in 14 patients for whom the last previous lumbar sympathetic block performed by using the conventional paravertebral method was unsuccessful. Under fluoroscopic guidance, the needle was inserted transdiscally at L2-3 and/or L3-4 and was advanced until its tip pierced the anterior longitudinal ligament. Radiography and computed tomography revealed that the injected contrast media spread along the anterolateral surface of the vertebral column without any flow into the psoas muscle. Alcohol was injected successfully in all patients. During the 1-mo follow-up period, no patients had any symptom of genitofemoral neuritis. Thirteen patients who had been suffering from lower extremity pain achieved partial or complete pain relief. One patient with plantar hyperhidrosis achieved persistent anhidrosis. These results suggest that the transdiscal approach can be a technical option for neurolytic lumbar sympathetic block. ⋯ Neurolytic lumbar sympathetic block was performed with the needle advanced through the intervertebral disc. With this technique, the risk of genitofemoral neuritis, the most common complication after neurolytic lumbar sympathetic block, was reduced because the needle does not penetrate the psoas muscle, through which the genitofemoral nerve passes.
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Anesthesia and analgesia · Dec 1997
Meta AnalysisDrugs to minimize perioperative blood loss in cardiac surgery: meta-analyses using perioperative blood transfusion as the outcome. The International Study of Peri-operative Transfusion (ISPOT) Investigators.
Concern about the side effects of allogeneic red blood cell transfusion has increased interest in methods of minimizing perioperative transfusion. We performed meta-analyses of randomized trials evaluating the efficacy and safety of aprotinin, desmopressin, tranexamic acid, and epsilon-aminocaproic acid in cardiac surgery. All identified randomized trials in cardiac surgery were included in the meta-analyses. The primary outcome was the proportion of patients who received at least one perioperative allogeneic red cell transfusion. Sixty studies were included in the meta-analyses. The largest number of patients (5808) was available for the meta-analysis of aprotinin, which significantly decreased exposure to allogeneic blood (odds ratio [OR] 0.31, 95% confidence interval [CI] 0.25-0.39; P < 0.0001). The efficacy of aprotinin was not significantly different regardless of the type of surgery (primary or reoperation), aspirin use, or reported transfusion threshold. The use of aprotinin was associated with a significant decrease in the need for reoperation because of bleeding (OR 0.44, 95% CI 0.27-0.73; P = 0.001). Desmopressin was not effective, with an OR of 0.98 (95% CI 0.64-1.50; P = 0.92). Tranexamic acid significantly decreased the proportion of patients transfused (OR 0.50, 95% CI 0.34-0.76; P = 0.0009). Epsilon-aminocaproic acid did not have a statistically significant effect on the proportion of patients transfused (OR 0.20, 95% CI 0.04-1.12; P = 0.07). There were not enough patients to exclude a small but clinically important increase in myocardial infarction or other side effects for any of the medications. We conclude that aprotinin and tranexamic acid, but not desmopressin, decrease the number of patients exposed to perioperative allogeneic transfusions in association with cardiac surgery. ⋯ Aprotinin, desmopressin, tranexamic acid, and epsilon-aminocaproic acid are used in cardiac surgery in an attempt to decrease the proportion of patients requiring blood transfusion. This meta-analysis of all published randomized trials provides a good estimate of the efficacy of these medications and is useful in guiding clinical practice. We conclude that aprotinin and tranexamic acid, but not desmopressin, decrease the exposure of patients to allogeneic blood transfusion perioperatively in relationship to cardiac surgery.
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Anesthesia and analgesia · Dec 1997
Randomized Controlled Trial Comparative Study Clinical TrialContribution of the spinal cord to arousal from inhaled anesthesia: comparison of epidural and intravenous fentanyl on awakening concentration of isoflurane.
To investigate the contribution of modulation of afferent nociceptive inputs by an opioid in the spinal cord to arousal from inhaled anesthesia, we determined the awakening concentration of isoflurane in 50 unpremedicated patients scheduled for abdominal hysterectomy. Patients were assigned randomly to three groups. Group I received bolus injections of both epidural and intravenous (I.V.) saline, followed by both epidural and I.V. infusions at the rate of 0.2 mL x kg(-1) h(-1). Group II received an I.V. injection of fentanyl 2 microg/kg, followed by an infusion at the rate of 25 ng x kg(-1) x min(-1), and Group III received an epidural injection and infusion in the same administration regimen as Group II. Anesthesia was induced with and maintained by isoflurane in an air/oxygen mixture (fraction of inspired oxygen = 0.5) with no adjuvant drugs. The study drug was administered at the start of retroperitoneal suturing. The awakening concentrations of isoflurane in Groups I, II, and III (mean +/- SD) were 0.32% +/- 0.07%, 0.31% +/- 0.06%, and 0.24% +/- 0.06%, respectively. At that time, plasma fentanyl concentrations in Groups II and III were 1.12 +/- 0.09 ng/mL and 0.65 +/- 0.04 ng/mL, respectively. Epidural fentanyl infusion reduced the awakening concentration of isoflurane more (P < 0.01) than I.V. fentanyl infusion, despite the lower plasma concentration (P < 0.01) in the epidural group. These findings suggest that epidural fentanyl delays arousal from inhaled anesthesia by modulating the afferent nociceptive inputs in the spinal cord. The spinal cord may contribute to arousal from inhaled anesthesia through the regulation of afferent inputs by opioids along with the supraspinal region of the central nervous system (CNS), even if the effects of subarachnoid fentanyl on the higher CNS via the cephalad migration is taken into consideration. ⋯ The present study revealed that the spinal cord, the lower level of central nervous system, contributed to arousal from general anesthesia, along with the higher central nervous system, by comparing the concentrations of an inhaled anesthetic, isoflurane, in the expiration of patients receiving systemic or regional administration of an opioid, fentanyl.