Evaluation of maximal inspiratory pressure (Pi Max), Airway Occlusion Tracheal Pressure (P 01) and its ratio in weaning outcome of mechanical ventilation / Avaliação da força muscular inspiratória (Pi Max), da atividade do centro respiratório (P 0.1) e da relação da atividade do centro respiratório/força muscular inspiratória (P 0.1 / Pi Max) sobre o desmame da ventilação mecânica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Introduction: We hypothesized that maximal inspiratory pressure (Pi Max), airway tracheal occlusion pressure (P 0.1) and its ratio (P 0.1/Pi Max) can be used to predict weaning outcome in a mixed ICU mechanically ventilated patients. Methods: Pi Max, P 0.1 and P 0.1 / Pi Max ratio were measured in seventy consecutive intubated or tracheostomized, mechanically ventilated patients, who fulfilled weaning criteria. After these measurements of Pi Max, P0.1, respiratory rate and expiratory tidal volume (L) with the calculation of f / Vt ratio and the product P0.1x f / Vt , the patients were submitted to a spontaneous breathing trial (SBT) . Those who were able to sustain the SBT and had no need to return to mechanical ventilation in the following 24 hours were considered weaned. The sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy and Receiver- operating-characteristics (ROC) curves for this population were calculated. Results: The mean value of P 0.1 , Pi Max, P 0.1 / Pi Max, FR / VC e P 0.1 x FR /VC were 2,49 ±1,2, -34,6± 13, 0,07± 0,01, 75,4±33 and 184,6±123 respectively for the weaned patients and 4,36± 2,0, -32,1±11,0 , 0,15± 0,09, 148,4± 42 e 652,9± 358 for the not weaned patients. All the indexes distinguished between the weaned and not weaned patient, except for the Pi Max. The sensitivity for the P 0.1 , Pi Max, P 0.1 / Pi Max, FR / VC and P 0.1 x FR /VC were respectively 78,85, 65,38, 80,77, 82,69, 88,46. The specificity for P 0.1 , Pi Max, P 0.1 / Pi Max, FR / VC and P 0.1 x FR /VC were 72,2, 38,8, 72,2, 83,3, 72,2 respectively. The positive predictive value for P 0.1 , Pi Max, P 0.1 / Pi Max, FR / VC and P 0.1 x FR /VC were respectively 89,1, 75,5, 89,3, 93,4 e 90,2. The negative predictive value for P 0.1 , Pi Max, P 0.1 / Pi Max, FR / VC and P 0.1 x FR /VC were respectively 54,1, 28,0, 56,5, 62,5 e 68,4. The diagnostic accuracy for P 0.1 , Pi Max, P 0.1 / Pi Max, FR / VC and P 0.1 x FR /VC were respectively 77,1, 58,5, 78,5, 82,8 e 84,2. The area under the ROC curves for P 0.1 , Pi Max, P 0.1 / Pi Max, FR / VC and P 0.1 x FR /VC were respectively 0,76± 0,06, 0,52±0,08 , 0,78±0,06, 0,90±0,04 e 0,84±0,05. The comparison among the areas under the ROC curves showed that the best weaning indexes were f / Vt ratio, the product P 0.1 x f / Vt and the P0.1/ Pi Max ratio with no statistic differences among them. The Pi Max presented the smaller area under the ROC curve. The weaning indexes P 0.1, Pi Max e P 0.1/ Pi Max were not statistically different between intubated or tracheostomized patients. Conclusion: The best weaning indexes were f/Vt ratio , the product P 0.1 x f/Vt and the P 0.1 / Pi Max ratio with no statistically difference among them.

ASSUNTO(S)

ventilators mechanical/utilization respiration artificial desmane do respirador/métodos respiração artificial respiratory muscles/physiopathology respiratory center/physiopathology músculos respiratórios/fisiopatologia ventilator weaning/methods centro respiratório/fisiopatologia respiradores mecânicos/utilização

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