Mechanical power normalized to lung-thorax compliance indicates weaning readiness in prolonged ventilated patients

Alessandro Ghiani,Swenja Walcher,Konstantinos Tsitouras,Nikolaus Kneidinger,Joanna Paderewska,Claus Neurohr

doi:10.1038/s41598-021-03960-y

Abstract

Since critical respiratory muscle workload is a significant determinant of weaning failure, applied mechanical power (MP) during artificial ventilation may serve for readiness testing before proceeding on a spontaneous breathing trial (SBT). Secondary analysis of a prospective, observational study in 130 prolonged ventilated, tracheotomized patients. Calculated MP’s predictive SBT outcome performance was determined using the area under receiver operating characteristic curve (AUROC), measures derived from k-fold cross-validation (likelihood ratios, Matthew's correlation coefficient [MCC]), and a multivariable binary logistic regression model. Thirty (23.1%) patients failed the SBT, with absolute MP presenting poor discriminatory ability (MCC 0.26; AUROC 0.68, 95%CI [0.59‒0.75], p = 0.002), considerably improved when normalized to lung-thorax compliance (LTCdyn-MP, MCC 0.37; AUROC 0.76, 95%CI [0.68‒0.83], p < 0.001) and mechanical ventilation PaCO2 (so-called power index of the respiratory system [PIrs]: MCC 0.42; AUROC 0.81 [0.73‒0.87], p < 0.001). In the logistic regression analysis, PIrs (OR 1.48 per 1000 cmH2O2/min, 95%CI [1.24‒1.76], p < 0.001) and its components LTCdyn-MP (1.25 per 1000 cmH2O2/min, [1.06‒1.46], p < 0.001) and mechanical ventilation PaCO2 (1.17 [1.06‒1.28], p < 0.001) were independently related to SBT failure. MP normalized to respiratory system compliance may help identify prolonged mechanically ventilated patients ready for spontaneous breathing.

Highlights

Mechanical ventilation, the core characteristic of intensive care, is a life-saving procedure for patients presenting severe respiratory failure
Apart from clinical factors (e. g., evidence of clinical improvement, P/F ratio, adequate hemodynamics), several prediction variables have been assessed in a one-time measurement for readiness testing[4,5,6], with most of these traditional weaning predictors used to distinguish between patients who can or cannot sustain a trial of spontaneous breathing usually determined after a short period of self-ventilation following disconnection from the ventilator[4]
Not total power output but critical stress imposed on respiratory muscles (e. g. expressed as pressure–time product or tension-time index of the diaphragm) seems to be the major determinant of weaning failure[8,10]

Summary

Introduction

Mechanical ventilation, the core characteristic of intensive care, is a life-saving procedure for patients presenting severe respiratory failure. G., evidence of clinical improvement, P/F ratio, adequate hemodynamics), several prediction variables (e.g., maximum inspiratory pressure, tidal volume, or minute ventilation) have been assessed in a one-time measurement for readiness testing[4,5,6], with most of these traditional weaning predictors used to distinguish between patients who can or cannot sustain a trial of spontaneous breathing usually determined after a short period of self-ventilation following disconnection from the ventilator[4]. In a retrospective analysis, mechanical power normalized to lung-thorax compliance, a surrogate of applied power per unit of ventilated lung volume (consistent with stress intensity), was independently associated with the outcome of a spontaneous breathing trial[12] In this analysis, we evaluated the discriminatory performance of mechanical power in predicting the outcome of a short weaning trial and indicate weaning readiness

Methods

Results

Conclusion