Acute respiratory failure and echocardiographic examination

Acute respiratory failure, a condition frequently fraught with haemodynamic instability, is one of the most frequent reasons for admission to the intensive care ward. Obligatory questions in every patient concern the left ventricular function and assessment of the left atrial and left ventricular filling pressures. The prognosis and management of respiratory failure also depend on assessment of the right ventricular function and pulmonary circulation. A complex echo protocol is warranted to judiciously decide on the treatment strategy including optimization of the patient's preload, contractility, heart rate and afterload. This allows for effective treatment of respiratory disequilibrium, which can continue to be monitored by means of ultrasound. Monitoring of the lung parenchyma and pleural space enables the physician to obtain additional data supporting the echocardiography findings, assisting the decision making on the ventilation strategy, the need for bronchoscopy, pleural drainage and to determine optimal patient position including prone postitioning. The appropriateness of prescribed therapy for the acute respiratory failure management can then be monitored by bedside echocardiography and lung ultrasonography in the attempt to optimize pulmonary gas exchange without haemodynamic alteration, and also to improve the patient's haemodynamic status without adding an unnecessary burden to the respiratory system. As the respiratory failure responds to treatment, echocardiography can then assist with weaning and termination of ventilatory support. Where the respiratory failure is critical, rapid assessment with echocardiography and chest ultrasound helps in the decision-making as to whether to proceed to extracorporeal lung assist (ECLS) support and if adopted, its optimal configuration. ECLS requires ultrasound modalities for correct indication, management and weaning of this mode of support. Echocardiographic monitoring of patients in acute respiratory failure is indispensable and an ultrasonic device should be considered essential equipment for every intensive care unit.

Keywords: acute respiratory failure; echocardiography; ultrasonography; chest ultrasonography; intensive care; intermittent positive pressure ventilation; extracorporeal membrane oxygenation