Anesthesia and analgesia
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Anesthesia and analgesia · Feb 1999
Clinical Trial Controlled Clinical TrialEpidural steroids for treating "failed back surgery syndrome": is fluoroscopy really necessary?
Epidural steroids are commonly administered in the treatment of "failed back surgery syndrome." Because patient response is dependent on accurate steroid placement, fluoroscopic guidance has been advocated. However, because of ever-increasing medical expenditures, the cost-benefit of routine fluoroscopy should be critically evaluated. Therefore, 50 patients were enrolled into this institutional review board-approved, prospective, controlled, single-blinded study. At a predetermined intervertebral level, the epidural space was identified using an air loss of resistance technique. Thereafter, an epidural catheter was inserted 2 cm through the epidural needle. To determine the accuracy of the clinical placement, contrast medium was administered through the epidural catheter; antero-posterior and lateral lumbar spine radiographs were then obtained. The number of attempts required to successfully locate the epidural space, the reliability of the air loss of resistance technique in indicating successful epidural penetration in failed back surgery syndrome, the ability of the clinician to accurately predict the intervertebral space at which the epidural injection was performed, and the spread of contrast medium within the epidural space were recorded. A total of 48 epidurograms were performed. The number of attempts to successfully enter the epidural space was 2 +/- 1. In 44 cases, the radiological studies confirmed the clinical impression that the epidural space had been successfully identified. In three patients, the epidural catheter was in the paravertebral tissue. One myelogram was recorded. In 25 patients, the epidural catheter did not pass through the predetermined intervertebral space. In 35 cases, the contrast medium did not reach the level of pathology. ⋯ The clinical sign of loss of resistance is a reliable indicator of epidural space penetration in most cases of "failed back surgery syndrome." However, surface anatomy is unreliable and may result in inaccurate steroid placement. Finally, despite accurate placement, the depot-steroid solution will spread to reach the level of pathology in only 26% of cases.
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Anesthesia and analgesia · Feb 1999
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of prostaglandin E1 on intraoperative temperature changes and the incidence of postoperative shivering during deliberate mild hypothermia for neurosurgical procedures.
We investigated the effects of i.v. prostaglandin E1 (PGE1) on intraoperative changes of core temperature and the incidence of postoperative shivering in neurosurgical patients undergoing deliberate mild hypothermia. Eighty-three patients were randomly assigned to one of three groups: patients in the control group did not receive PGE1, whereas patients in the PG20 group and PG50 group received PGE1 at a dose of 0.02 and 0.05 microg x kg(-1) x min(-1), respectively. The administration of PGE1 was started just after the induction of anesthesia and continued until the end of anesthesia. Anesthesia was maintained with nitrous oxide in oxygen, sevoflurane, and fentanyl. After the induction of anesthesia, patients were cooled using a water blanket and a convective device blanket. Tympanic membrane temperature was maintained at 34.5 degrees C. During surgical wound closure, patients were rewarmed. Intraoperative changes in tympanic membrane and skin temperatures and the incidence of postoperative shivering were compared among groups. Demographic and intraoperative variables were similar among groups. There were no significant differences in tympanic temperatures among groups at each point during the operation. Skin temperature 30 min after rewarming and just after tracheal extubation was significantly lower in the PG20 group than in the PG50 group. Postoperative shivering was more frequent in the PG20 group (43%) than in the control (13%) and PG50 (17%) groups. These results suggest that the intraoperative administration of PGE1 does not affect changes in core temperature during deliberate mild hypothermia and that PGE1 at a dose of 0.02 microg x kg(-1) x min(-1) may increase the occurrence of postoperative shivering. ⋯ Deliberate mild hypothermia has been proposed as a means of providing cerebral protection during neurosurgical procedures. Vasodilating drugs may be used during deliberate mild hypothermia to maintain peripheral circulation and to enhance the cooling and rewarming rate. In the present study, however, we found no benefit from i.v. prostaglandin E1 administration during deliberate mild hypothermia in neurosurgical patients.
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Anesthesia and analgesia · Feb 1999
Comparative StudyThe effects of clonidine and dexmedetomidine on human neutrophil functions.
Neutrophil functions are inhibited by various anesthetics. Clonidine and dexmedetomidine, alpha2-agonists, are often used as adjuncts to anesthesia. Thus, we conducted the current study to determine the effect of clonidine, dexmedetomidine, and xylazine at clinically (or veterinary anesthetically) relevant concentrations (and 10 and 100 times these concentrations) on several aspects of human neutrophil functions using an in vitro system. The three alpha2-agonists had no effects on chemotaxis, phagocytosis, or superoxide anion (O2-) production of neutrophils, except that the highest concentration of clonidine inhibited chemotaxis. Increases in intracellular calcium concentrations in neutrophils stimulated by chemotaxin were not influenced by clonidine, dexmedetomidine, or xylazine. Unchanged calcium concentrations may contribute to failure to modulate the neutrophil functions. In addition, these drugs did not scavenge O2- generated by the cell-free (xanthine-xanthine oxidase) system. This is the first report concerning the effect of clonidine or dexmedetomidine on human neutrophil functions. Our findings suggest that we may not have to take extra precautions in using the alpha2-agonists in patients with infection, but that we cannot expect these drugs to be prophylaxis against autotissue injuries whose pathogenesis includes activation of neutrophils. ⋯ Neutrophils are involved in the antibacterial host defense system and autotissue injury. We found that clinically relevant concentrations of clonidine and dexmedetomidine do not affect chemotaxis, phagocytosis, or superoxide production by human neutrophils. These findings indicate that it may not be necessary to take special care in using alpha2-agonists in patients with infection, sepsis, or systemic inflammation.
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Anesthesia and analgesia · Feb 1999
Comparative StudyBeta-adrenergic blockers and vasovagal episodes during shoulder surgery in the sitting position under interscalene block.
Shoulder surgery is often performed with patients in the sitting position under interscalene block anesthesia. Vasovagal episodes, characterized by a sudden decrease in heart rate and/or blood pressure, have a reported incidence of 17%-24% in this setting. We performed a retrospective study to determine whether there was an association between the use of beta-adrenergic blockers and the incidence of these episodes. Of the 150 patients identified, 20 (13.3%) had a vasovagal event. Similar proportions of patients had received a beta-adrenergic blocker in the group who had a vasovagal event compared with those who did not (20% vs 18%; P = 0.95). No other differences could be identified. We conclude that vasovagal episodes occur frequently in this setting with no identifiable risk factors. Beta-adrenergic blockers were not associated retrospectively with either an increased or decreased incidence of these episodes. The most likely mechanism involves the Bezold-Jarisch reflex. ⋯ In this retrospective study of 150 patients who underwent shoulder surgery in the sitting position under interscalene block, we found a 13% incidence of vasovagal episodes. Unlike a previous study, this was not affected by the use of beta-blockers. A randomized, prospective study is necessary to clarify this issue.
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Anesthesia and analgesia · Feb 1999
Comparative StudyCraniotomy procedures are associated with less analgesic requirements than other surgical procedures.
The conventional wisdom that neurosurgical patients experience minimal postoperative pain and require little analgesia has been challenged. To address this, we reviewed our anesthesia and postanesthesia care unit (PACU) records for 1995 and compared pain management in patients undergoing major intracranial and selected extracranial procedures. We recorded patient weight, operative time, time in the PACU, intraoperative and postoperative opioid use, PACU pain scores, and level of consciousness in patients who had undergone open fixation of mandible or maxilla (Group E), clipping of aneurysms or excision of tumors (Group I), or lumbar laminectomy (Group L). Group I (n = 78) patients received less fentanyl in the operating room (0.016 microg x kg(-1) x min(-1) versus 0.023 microg x kg(-1) x min(-1) for Group E [n = 134] and 0.023 microg x kg(-1) x min(-1) for Group L [n = 21]; P < 0.05), received less morphine in the PACU (0.0004 vs 0.0013 vs 0.0015 mg kg(-1) x min(-1); P < 0.005), reported lower pain scores (0.76 vs 2.5 vs 2.4; P < 0.05), and spent less time in the PACU (89.5 vs 109 vs 105 min; P < 0.05) than Group E or L patients. Our results were similar when only patients with Glasgow Coma Scale scores > or = 14 were used in a subset analysis. We conclude that patients suffer less pain and use fewer opioids in the PACU after intracranial surgery than after facial reconstruction or lumbar laminectomy. Our results confirm that the average craniotomy patient has less postoperative pain than patients who undergo other surgical procedures, although patients who undergo frontal craniotomy may require more aggressive pain management. ⋯ This study compares the pain report and analgesic use in patients after intracranial versus extracranial surgery. The results confirm the commonly held but recently challenged belief that neurosurgery patients suffer less pain postoperatively than other patients. In this study, we found that most patients report minimal pain after intracranial surgery but that a small subset of patients, many of whom have undergone frontal craniotomies, require aggressive treatment of postoperative pain.