By Dr Czarina Leung, QMH
Introduction: Mechanical ventilation (MV) is a crucial intensive care unit (ICU) tool, however its use can cause diaphragmatic atrophy and dysfunction. Previous studies described ultrasound measurements of diaphragm thickness or excursion.
Objective: We hypothesize that diaphragmatic ultrasonography is a safe and effective tool for predicting ventilator weaning outcome in critically ill patients requiring MV.
Methods: We performed a prospective observational pilot study to evaluate the relationship of ultrasonographically measured percentage respiratory change of diaphragmatic thickness (∆tdi%)and diaphragmatic excursion with clinical outcome. We recruited 31 ICU patients upon necessitating MV. We performed serial ultrasound on bilateral diaphragm from start until end of MV period.
Results: For predictingweaning failure,decrease in ∆tdi% and excursion at the end of MV period were the best predictors [ROC AUC Left 0.979, Right 1.000; excursion AUC Left 0.986, Right 0.861]. Even first day values showed high negative predictive values (≥88.9%).For predicting MV duration, at least one side of the diaphragm showed increase ∆tdi% and excursion to be associated with shorter duration.
Conclusion: The diaphragmatic ultrasound measurements of ∆tdi% and excursion are safe to perform and feasible predictors of MV outcome. The best predictor of weaning failure is reduction of ∆tdi% and diaphragmatic excursion on last day. Application of these ultrasoundparametersmay help assess readiness for weaning.