Introduction
Detection and management of respiratory disease is of principal importance to the intensivist and acute care provider. In the most severe cases of respiratory failure, reconciling risk of deterioration with acquiring essential imaging studies is a common predicament. Interestingly, lungs, as historically thought, were impervious to the diagnostic capability of ultrasound and therefore, were described by many with sonographic indifference. Thanks to the painstaking work by Lichtenstein and many others,(1–5) it has emerged as an invaluable tool for the modern acute care provider to detect and manage cardio-respiratory disease in critically ill patients. Not only is it performed with ease, it is inexpensive, reproducible, requires no transport, yet offers a high degree of accuracy and precision in decrypting challenging cases of respiratory failure.
Whether it be undifferentiated respiratory failure, (2,6) assessment of volume status, (7–11) consolidation, (12,13) or assessment of pleural effusion,(14–17) its’ versatility in detection and management of a myriad of lung pathology is matched only by that of CT. Moreover, mounting evidence has demonstrated diagnostic superiority over chest radiography for life-threatening diseases including pneumothorax and pulmonary edema, especially in the setting of critical illness(1,10,12,15,18,19). International guidelines, published in 2012, provide a summation and critique of evidence for how this technique is best applied (5).
In this section, we will explore the use of critical care ultrasound in approaching the critically ill patient with a variety of cardio-respiratory diseases. We encourage those individuals who care for acutely ill patients to consider exploring this technology and how it can be used to aid clinical decision making.

Indications
Indications that will be covered in this section include:
1. Undifferentiated respiratory failure
2. Volume status assessment
3. Identification of pneumothorax
4. Distinguishing consolidation from pleural effusion
5. Investigating quality and quantity of pleural effusions; procedural guidance
6. Interrogation of weaning failure