Ultrasonographic Evaluation of Positive End-Expiratory Pressure–induced Lung Recruitment: Comparison with the Recruitment-to-Inflation Ratio

Application of an optimal level of positive end-expiratory pressure (PEEP) is a crucial facet of optimizing mechanical ventilation among hypoxic patients. PEEP titration is usually guided by improvement in oxygenation and increase in the static compliance. The ARDSNet table recommends PEEP levels based on the FiO2 requirement. There are drawbacks associated with these methods of PEEP titration. The PaO2 levels may rise with an increase in the PEEP level due to reduced right-left shunt in the lung, unrelated to the extent of recruitment. Besides, alveolar recruitment may not always lead to improved lung compliance. Ultrasonography enables direct visualization of the extent of lung recruitment on application of incremental levels of PEEP. However, hyperinflation of the relatively normal lung cannot be identified by ultrasonography. The recruitment to inflation ration (R/I) evaluates lung compliance at a high and a low level of PEEP and compares the lung compliance at both levels. The R/I ratio may be a predictor of hyperinflation in the relatively normal lung.

Patients with acute hypoxemic respiratory failure with potentially recruitable lungs on mechanical ventilation in the MICU. Its Prospective observational study and aim of the study is to Evaluate the efficacy of bedside lung ultrasonography to assess lung recruitment – correlate with the Recruitment/Inflation (R/I) ratio as a technique to identify hyperinflation of normal lungs.