Recent advances in cardiorespiratory monitoring in acute respiratory distress syndrome patients.

Background: Recent advances on cardiorespiratory monitoring applied in ARDS patients undergoing invasive mechanical ventilation and noninvasive ventilatory support are available in the literature and may have potential prognostic implication in ARDS treatment. Main body: The measurement of oxygen saturation by pulse oximetry is a valid, low-cost, noninvasive alternative for assessing arterial oxygenation. Caution must be taken in patients with darker skin pigmentation, who may experience a greater incidence of occult hypoxemia. Dead space surrogates, which are easy to calculate, have important prognostic implications. The mechanical power, which can be automatically computed by intensive care ventilators, is an important parameter correlated with ventilator-induced lung injury and outcome. In patients undergoing noninvasive ventilatory support, the use of esophageal pressure can measure inspiratory effort, avoiding possible delays in endotracheal intubation. Fluid responsiveness can also be evaluated using dynamic indices in patients ventilated at low tidal volumes (< 8 mL/kg). In patients ventilated at high levels of positive end expiratory pressure (PEEP), the PEEP test represents a valid alternative to passive leg raising. There is growing evidence on alternative parameters for evaluating fluid responsiveness, such as central venous oxygen saturation variations, inferior vena cava diameter variations and capillary refill time. Conclusion: Careful cardiorespiratory monitoring in patients affected by ARDS is crucial to improve prognosis and to tailor treatment via mechanical ventilatory support. Keypoints: The SpO2/FiO2 ratio, corrected minute ventilation and ventilatory ratio are valid surrogates for estimating gas exchange in ARDS patients, and caution should be taken in patients with darker skin pigmentation and moderate–severe ARDS. Changes in esophageal pressure during noninvasive respiratory support and mechanical power must be carefully monitored to estimate PSILI and VILI in ARDS patients undergoing mechanical ventilation. The use of dynamic indexes of fluid responsiveness should be encouraged in ARDS patients. Pulse pressure variation and stroke volume variation have also been validated in mechanically ventilated patients with low tidal volume. A possible alternative to passive leg raising in a mechanically ventilated patient is the PEEP test. Two minimally invasive alternatives to predict fluid responsiveness are changes in central venous oxygen saturation and capillary refill time after a passive leg raising or a fluid challenge. [ABSTRACT FROM AUTHOR]