Understanding the importance of ventilator management is a crucial facet of emergency medicine. Emergency physicians are well known for their expertise in emergent airway management, but securing the airway is only a fraction of their role. Mechanical ventilation (MV) is an essential tool for critically ill patients. If not applied correctly, it can worsen the clinical course and increase morbidity and mortality.1 In the past two decades, our understanding of ventilator-induced lung injury (VILI) has resulted in the challenging of conventional practices, such as using lower tidal volumes. With the current crisis of emergency department (ED) overcrowding, critical care patients have increased lengths of stay in the ED and, at times, are boarded for several hours or even days until a bed is available in the intensive care unit (ICU).2,3 The emergency physician must understand critical care topics and the intricacies of MV for heterogeneous patient populations with varying pathologies—no “single setting fits all.” With special consideration of each patient's needs, both patient care and outcomes will improve.
Indications for intubation and institution of MV fall under three basic categories: respiratory failure, airway protection, and anticipation of the clinical course.
The most common indication for MV is respiratory failure. These patients frequently have either hypoventilation or a decreased ability to manage the work of breathing. This can lead to hypoxemia, hypercapnia, or both. Hypoxemia is often defined as a Po2 less than 60 mm Hg. Hypercapnia is defined as an “elevated” Pco2. In contrast to hypoxemia, hypercapnia is difficult to strictly define, as it is a component of hypoventilation directly resulting in elevation of CO2. An exact number is less important than the clinical picture and varies in the literature. In certain populations, such as patients with COPD who chronically retain CO2, a higher baseline Pco2 of 45–55 mm Hg can be well tolerated. An acute rise in CO2 from the patient's baseline will cause lethargy, sleepiness, confusion, and altered mental status. In these hypercapnic patients, the primary action of MV is the promotion of appropriate alveolar ventilation with an end goal of proper CO2 clearance.
Another indication for the institution of MV is to protect the airway from potential aspiration of various etiologies. Common indications include acute intoxication, altered mental status from infection, or massive upper gastrointestinal hemorrhage.
Last, the predicted clinical course will often dictate securing an airway to facilitate either workup or definitive treatment. Patients in a questionable condition may need further diagnostic testing away from the critical resources of the ED, placing them at risk of sudden deterioration “in the hallway of radiology.” These patients should be placed on MV prior to leaving the ED.
There are no absolute contraindications for MV. There are, however, minor adverse effects of MV. The placement of an endotracheal tube takes away the protective functions of the upper ...