Buspirone and meperidine synergistically reduce the shivering threshold.

UNLABELLED: Mild hypothermia (i.e., 34 degrees C) may prove therapeutic for patients with stroke, but it usually provokes shivering. We tested the hypothesis that the combination of buspirone (a serotonin 1A partial agonist) and meperidine synergistically reduces the shivering threshold (triggering tympanic membrane temperature) to at least 34 degrees C while producing little sedation or respiratory depression. Eight volunteers each participated on four randomly-assigned days: 1) large-dose oral buspirone (60 mg); 2) large-dose IV meperidine (target plasma concentration of 0.8 microg/mL); 3) the combination of buspirone (30 mg) and meperidine (0.4 microg/mL); and 4) a control day without drugs. Core hypothermia was induced by infusion of lactated Ringer's solution at 4 degrees C. The control shivering threshold was 35.7 degrees C +/- 0.2 degrees C. The threshold was 35.0 degrees C +/- 0.8 degrees C during large-dose buspirone and 33.4 degrees C +/- 0.3 degrees C during large-dose meperidine. The threshold during the combination of the two drugs was 33.4 degrees C +/- 0.7 degrees C. There was minimal sedation on the buspirone and combination days and mild sedation on the large-dose meperidine day. End-tidal PCO2 increased approximately 10 mm Hg with meperidine alone. Buspirone alone slightly reduced the shivering threshold. The combination of small-dose buspirone and small-dose meperidine acted synergistically to reduce the shivering threshold while causing little sedation or respiratory toxicity. IMPLICATIONS: Mild hypothermia may be an effective treatment for acute stroke, but it usually triggers shivering, which could be harmful. Our results indicate that the combination of small-dose buspirone and small-dose meperidine acts synergistically to reduce the shivering threshold while causing little sedation or respiratory toxicity. This combination may facilitate the induction of therapeutic hypothermia in stroke victims.

Extramedullary myeloid tumors in children: the limited value of local treatment.

PURPOSE: To determine the incidence of extramedullary tumors (EMT) in Saudi Arabian children with acute myeloid leukemia, the factors associated with these tumors and the impact of local treatment on local tumor control, complete remission and survival rates. PATIENTS AND METHODS: One hundred children, median age 6 years, who received their primary treatment for acute myeloid leukemia at King Faisal Specialist Hospital and Research Center, from 1983 to 1997 were studied. EMT at diagnosis occurred in 18 (18%) patients at 25 sites. Meningeal leukemia, hepatosplenomegaly, lymph node enlargement, gingival hypertrophy, and cutaneous infiltration were not included in the definition of EMT. With these exclusions, children with EMT were younger than those without EMT (median age, 3.5 v. 7.5 years) and were more likely to have meningeal leukemia at diagnosis (33% v. 10%). The t(8;21) translocation was associated with a 47% EMT incidence compared with 23% without the translocation. Local radiation treatment was given to 16 of 25 (64%) EMT sites. RESULTS: The overall 5-year survival rate for all patients was 28%, and this was not significantly influenced by the drug regimen used, meningeal leukemia at diagnosis, the presence of the (8;21) translocation, M4 and M5 morphology combined, or EMT at diagnosis. Significant differences were observed in the 5-year survival rates for patients who underwent allogeneic bone marrow transplantation (52%; N = 37) and those who attained complete remission (CR) but did not undergo transplantation (21%; N = 44) and those who did not achieve complete remission with initial therapy (5%; N = 19). Systemic and local EMT CR was achieved in 17 of 18 patients with EMT, including 12 patients who underwent radiation treatment and 5 of 6 of those who did not. Isolated relapse was not seen at an EMT site and was not noted at any later stage of the disease. CONCLUSIONS: Permanent local control at sites of EMT was achieved in all patients who attained a bone marrow CR, whether or not the site was irradiated. Local radiation treatment of an EMT site did not appear to contribute to overall CR and survival rates. The use of radiation treatment should be conservative and limited to patients in whom there is a real and immediate threat to vision or renal function or when the spinal cord is compromised.