Respiratory Rate as a Predictor of Weaning Failure from Mechanical Ventilation

Background and objectiveThere is not an ideal predictor of weaning from mechanical ventilation (MV). In a large meta-analysis, despite methodological limitations, respiratory rate (RR) was considered a promising predictor. The aim of this study was to evaluate RR as a predictor of weaning failure from MV.MethodsWe prospectively evaluated 166 patients scheduled for weaning from MV. RR and other essential criteria for weaning were evaluated at an early stage of screening. Patients who met the essential screening criteria for weaning underwent spontaneous breathing trial. RR was compared with the following outcomes: weaning success/failure or extubation failure.ResultsWeaning success was present in 76.5% and weaning failure in 17.5% of patients. There were 6% of reintubations. The predictive power for RR weaning failure, RR best cut-off point > 24 breaths per minute (rpm), was: sensitivity 100%, specificity 85%, and accuracy 88% (ROC curve, p < 0.0001). Of the patients with weaning failure, 100% were identified by RR during screening (RR cut-off > 24 rpm). There were 15% false positives, weaning successes with RR > 24 rpm.ConclusionRR was an effective predictor of weaning failure. The best cut-off point was RR > 24 rpm, which differed from those reported in the literature (35 and 38 rpm). Only 6% of patients were reintubated, but RR or other weaning criteria did not identify them.

ResumoObjetivos e justificativasNao existe um preditor de desmame da ventilacao mecanica (VM) ideal. Numa grande metanalise, apesar de limitacoes metodologicas, a frequencia respiratoria (FR) foi considerada um preditor promissor. O objetivo deste estudo foi avaliar a FR como um preditor de falha de desmame da VM.MetodoAvaliamos prospectivamente 166 pacientes destinados ao desmame da VM. A FR e outros parametros essenciais para desmame foram avaliados numa fase inicial de triagem. Os pacientes que apresentaram na triagem os parametros essenciais para desmame foram submetidos ao teste de respiracao espontanea. A FR foi comparada com os desfechos: sucesso, falha de desmame ou falha de extubacao.ResultadosSucesso de desmame em 76,5% e falha de desmame em 17,5% dos pacientes. Seis por cento de reintubacoes. O poder preditivo para falha de desmame da FR, melhor ponto de corte FR > 24 respiracoes por minuto (rpm), foi: sensibilidade de 100%, especificidade de 85% e acuracia de 88% (curva ROC, p < 0,0001). Dos pacientes com falha de desmame, 100% foram identificados pela FR na fase de triagem (corte FR > 24 rpm). Houve 15% de falsos positivos, sucessos de desmame com FR > 24 rpm.ConclusaoA FR foi um preditor eficiente de falha de desmame. Encontrou-se como melhor ponto de corte FR > 24 rpm, diferentemente daqueles referidos pela literatura (35 e 38 rpm). Apenas 6% dos pacientes foram reintubados e tanto a FR quanto os outros parametros para desmame nao tiveram capacidade de identifica-los.