Risk factors for postoperative hypothermia in the post-anesthetic care unit: a prospective prognostic pilot study / Fatores de risco para hipotermia pós-operatória em sala de recuperação pós-anestésica: estudo piloto prospectivo de prognóstico

Abstract Background: Hypothermia occurs in up to 20% of perioperative patients. Systematic postoperative temperature monitoring is not a standard of care in Brazil and there are few publications about temperature recovery in the postoperative care unit. Design and setting: Multicenter, observational, cross-sectional study, at Hospital de Base do Distrito Federal and Hospital Materno Infantil de Brasília. Methods: At admission and discharge from postoperative care unit, patients undergoing elective or urgent surgical procedures were evaluated according to tympanic temperature, vital signs, perioperative adverse events, and length of stay in postoperative care unit and length of hospital stay. Results: 78 patients, from 18 to 85 years old, were assessed. The incidence of temperatures <36 ºC at postoperative care unit admission was 69.2%. Spinal anesthesia (p < 0.0001), cesarean section (p = 0.03), and patients who received morphine (p = 0.005) and sufentanil (p = 0.003) had significantly lower temperatures through time. During postoperative care unit stay, the elderly presented a greater tendency to hypothermia and lower recovery ability from this condition when compared to young patients (p < 0.001). Combined anesthesia was also associated to higher rates of hypothermia, followed by regional and general anesthesia alone (p < 0.001). Conclusion: In conclusion, this pilot study showed that perioperative hypothermia is still a prevalent problem in our anesthetic practice. More than half of the analyzed patients presented hypothermia through postoperative care unit admission. We have demonstrated the feasibility of a large, multicenter, cross-sectional study of postoperative hypothermia in the post-anesthetic care unit.

Resumo Justificativa: A hipotermia ocorre em até 20% dos pacientes no perioperatório. A monitoração sistemática pós-operatória da temperatura não é um padrão de atendimento no Brasil e há poucas publicações sobre recuperação da temperatura na sala de recuperação pós-anestésica. Desenho e cenário: Estudo multicêntrico, observacional, transversal, conduzido no Hospital de Base do Distrito Federal e no Hospital Materno Infantil de Brasília. Métodos: Na admissão e alta da sala de recuperação pós-anestesia, os pacientes submetidos a procedimentos cirúrgicos eletivos ou de urgência foram avaliados de acordo com a temperatura timpânica, sinais vitais, eventos adversos perioperatórios, tempo de permanência na sala de recuperação pós-anestesia e tempo de internação hospitalar. Resultados: Setenta e oito pacientes com idades entre 18 e 85 anos foram avaliados. A incidência de temperatura <36 ºC na admissão à sala de recuperação pós-anestesia foi de 69,2%. Raquianestesia (p < 0,0001), cesariana (p = 0,03) e os pacientes que receberam morfina (p = 0,005) e sufentanil (p = 0,003) apresentaram temperaturas significativamente menores ao longo do tempo. Durante a permanência na sala de recuperação pós-anestesia, os pacientes idosos apresentaram uma tendência maior a apresentarem hipotermia e menor capacidade de recuperação dessa condição, em comparação com os pacientes jovens (p < 0,001). Anestesia combinada também foi associada a taxas mais altas de hipotermia, seguida pelas anestesias regional e geral isoladas (p < 0,001). Conclusão: Em conclusão, este estudo piloto mostrou que a hipotermia perioperatória ainda é um problema prevalente em nossa prática anestésica. Mais de metade dos pacientes analisados apresentaram hipotermia durante a admissão à sala de recuperação pós-anestésica. Demonstramos a viabilidade de um grande estudo multicêntrico, transversal, de hipotermia pós-operatória em sala de recuperação pós-anestésica.

Multidrug resistance in leukemias: the problem and some approaches to its circumvention

The phenomenon of multidrug resistance (MDR), representing cross-resistance among a number of unrelated chemotherapeutic drugs, is the major cause of chemotherapy failure in many tumors. It has been also detected in leukemias and in these cancers, as well as in many others, resistance can be reversed by a number of substances known as modulators or reversing agents. The capacity of identifying tumors resistant to chemotherapy could orientate the treatment employed. In leukemias, tumor cells are easily obtainable and many techniques have been used to evaluate resistance in these cells. Studying 42 leukemia patients we found a correlation of nearly 60 per cent among surface expression of P-glycoprotein, in vitro resistance reversal by cyclosporin A (CS-A) and extrusion of the rhodamine 123 dye. This latter assay has the advantage of measuring a functional aspect related to resistance (intracellular drug accumulation), being reproducible and affordable by most laboratories. The data generated by this assay were in accordance with those reported by other authors using different methods. To allow for an experimental approach in the study of MDR in leukemias, an in vitro model of a vincristine-induced erythroleukemia resistant cell line was established by us, and was shown to display MDR characteristics: resistance to unrelated drugs, surface expression of P-glycoprotein, extrusion of rhodamine 123 and resistance reversal by trifluoperazine, a reversing agent. Furthermore, this vincristine-resistant line was as sensitive to cell mediated lysis by natural killer (NK) cells as the parental line. Models like this one allow for the in vitro testing of new reversing agents, and when combined to in vitro tests for NK and LAK activity, may select for substances capable of modulating resistance without affecting a potentially useful cell mediated immunotherapy.