Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2003
Clinical TrialThe effect of graded hypothermia (36 degrees C-32 degrees C) on hemostasis in anesthetized patients without surgical trauma.
The isolated effects of hypothermia on hemostasis have not been investigated in healthy humans. We cooled 16 anesthetized patients scheduled for elective intracranial surgery to 32 degrees C body core temperature and assessed prothrombin time (PT), activated partial thromboplastin time, thrombelastogram (TEG), closure time, and platelet count at 36 degrees C, 34 degrees C, and 32 degrees C body core temperature after the induction of anesthesia but before surgical intervention. Activated partial thromboplastin time, hematocrit, and closure time did not change, whereas PT and platelet count decreased during cooling. Platelet count decreased without a decrease in hematocrit; hence, a dilution by administered fluids seemed unlikely. The small decrease of platelet count is probably clinically irrelevant in patients with normal platelet count and function. The small decrease in PT indicates an alteration of the extrinsic pathway of coagulation. TEG measurements showed a delay of clot formation in temperature-adjusted measurements but showed no change if the test temperature was 37 degrees C. This indicates that hypothermia reduces plasmatic coagulation and platelet reactivity. However, the clot strength is not altered by hypothermia. All coagulation variables remained within the normal ranges. Our results may indicate that moderate short-term (4-h) hypothermia has only minor adverse effects in healthy humans. We can make no statement about the effects of hypothermia of longer duration. ⋯ This study investigated the isolated effects of hypothermia in healthy anesthetized humans. We found only minor effects of body temperature reduction to 32 degrees C on assessed coagulation variables, indicating only minor effects in otherwise healthy humans.
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Anesthesia and analgesia · Jun 2003
Clinical TrialPerioperative myocardial ischemia in patients undergoing sternectomy shortly after coronary artery bypass grafting.
Coronary revascularization reduces cardiac complications associated with noncardiac surgery in patients with severe coronary disease. However, patients undergoing emergency noncardiac surgery soon after coronary bypass operations may still be vulnerable to ischemic myocardial events. We prospectively evaluated the incidence of myocardial ischemia in 82 consecutive patents scheduled for sternectomy in the first (Group 1; 35 patients) or second (Group 2; 47 patients) week after coronary artery bypass graft (CABG) surgery. The interval between CABG surgery and sternectomy in Groups 1 and 2 was 6 days (range, 4-7 days) and 11 days (range, 8-14 days), respectively. Electrocardiographic (ECG) changes consistent with myocardial ischemia were assessed with a two-channel Holter system for 48 h. There were no between-group differences in updated Acute Physiology and Chronic Health Evaluation score, use of beta-blockers, or perioperative hemodynamic changes. The incidence of ECG changes consistent with myocardial ischemia was fivefold more frequent in Group 1 (22.85% versus 4.25%; P < 0.05). Of the ischemic patients in Group 1, 25% experienced a perioperative acute myocardial infarction (one was fatal). There were no infarcts in Group 2. Thus, patients appear to be prone to coronary events during sternectomy performed early after CABG surgery. Although the incidence of ischemia did not differ from that previously reported after CABG surgery alone, further investigation is required to determine whether the findings obtained in this high-risk population are generalizable to patients undergoing noncardiac surgery soon after uneventful CABG surgery. ⋯ This study demonstrates an increased incidence of myocardial ischemia when sternectomy for mediastinitis is performed within one week of coronary artery bypass graft surgery, and this ischemia is associated with a 25% incidence of myocardial infarction.
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Anesthesia and analgesia · Jun 2003
Case ReportsPostdural puncture headache: an imaging-guided management protocol.
We propose an imaging-based algorithm for the management of headache caused by the inadvertent puncture of dura that occurs sporadically during epidural analgesia. Its implementation can identify those postdural puncture headache cases that cannot benefit from epidural blood patches, and their unnecessary application can consequently be avoided.
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Anesthesia and analgesia · Jun 2003
Comparative StudyCutaneous analgesia after transdermal application of amitriptyline versus lidocaine in rats.
Amitriptyline, a tricyclic antidepressant, has potent local anesthetic properties. However, there is no report of cutaneous analgesic effects after transdermal application. We report here that transdermally applied amitriptyline is more potent than lidocaine in providing cutaneous analgesia in rats. Solutions of amitriptyline base in 50, 100, and 500 mM concentrations were applied as a patch to rats, and their effects were compared with those of lidocaine base at the same concentrations and of the vehicle alone (45% water, 45% isopropyl alcohol, and 10% glycerin). Rats in each test group developed a concentration-dependent cutaneous analgesic block in the areas to which the drugs were applied; however, amitriptyline produced a longer block than lidocaine at the same concentration. The development of amitriptyline as a longer-lasting topical analgesic may improve our ability to treat chronic pain, such as neuropathic pain and neuralgia, and to prevent pain in procedures such as venipuncture. ⋯ The tricyclic antidepressant amitriptyline, often used perorally for the management of chronic pain, is shown here to be more potent than lidocaine in providing cutaneous analgesia when applied transdermally with an occlusive dressing in rats.
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Anesthesia and analgesia · Jun 2003
Randomized Controlled Trial Clinical TrialThe effect of dexamethasone on side effects after coronary revascularization procedures.
Corticosteroids decrease side effects after noncardiac elective surgery. We designed this randomized, double-blinded, placebo-controlled study to test the hypothesis that standard doses of dexamethasone (4 mg x2) would reduce postoperative nausea, vomiting, and pain, decrease the incidence of atrial fibrillation (AF), and improve appetite after cardiac surgery, thereby facilitating the recovery process. A total of 300 patients undergoing coronary revascularization surgery were enrolled in this clinical study. The anesthetic management was standardized in all patients. Dexamethasone (4 mg/mL) or saline (1 mL) was administered after the induction of anesthesia and a second dose of the same study drug was given on the morning after surgery. The incidence of AF was determined by analyzing the first 72 h of continuously recorded electrocardiogram records after cardiac surgery. The patients were assessed at 24- and 48-h intervals after surgery, as well as at the time of hospital discharge, to determine the incidence and severity of postoperative side effects (e.g., nausea, vomiting, pain) and patient satisfaction scores. Dexamethasone significantly reduced the need for antiemetic rescue medication on the first postoperative day (30% versus 42%), and the incidences of nausea (15% versus 26%) and vomiting (5% versus 16%) on the second postoperative day (P < 0.05). In addition, dexamethasone significantly reduced the percentage of patients with a depressed appetite on the second postoperative day. However, the corticosteroid failed to decrease the incidence of AF (27% versus 32%) or the total dosage of opioid analgesic medication administered in the postoperative period. We conclude that dexamethasone (8 mg in divided doses) was beneficial in reducing emetic symptoms and improving appetite after cardiac surgery. However, this dose of the corticosteroid does not seem to have antiarrhythmic or analgesic-sparing properties. ⋯ Dexamethasone (8 mg IV) was beneficial in reducing emetic symptoms and increasing appetite after cardiac surgery. However, this dose of the corticosteroid failed to decrease postoperative pain or the incidence of new-onset atrial fibrillation.