Respiratory Emergencies Study Guide for the CEN

Acute Respiratory Distress Syndrome (ARDS)

ARDS is a condition in which fluid accumulates in the alveoli in the lungs, damaging them, interfering with oxygenation, and stiffening the lung, which limits its ability to expand. ARDS is most common in patients who are already critically ill, such as patients hospitalized with severe cases of COVID-19 or pneumonia. The mortality rate for untreated patients is five to 30 percent.

Assessment

The primary symptom of ARDS is severe shortness of breath at rest that appears up to 72 hours after an infection or severe injury occurs. The patient will experience tachypnea and labored breathing in addition to cyanosis, hypoxia, and altered mental status due to poor oxygenation. Other symptoms include hypotension, tachycardia, and crackling/rales in the lungs.

As there is no definitive test for ARDS, diagnosing it is a process of ruling out other diagnoses, such as cardiac conditions. It is characterized by an acute onset, the presence of bilateral lung infiltrates on a chest X-ray or CT, and a PaO2/FiO2 ratio of less than 200 mm Hg, as determined by an ABG test.

Treatment

Patients with mild ARDS will receive supplemental oxygen via a nasal cannula or non-rebreather mask (NRM or NRB). Medications such as inhaled corticosteroids, inhaled surfactant, anti-inflammatory medications, and nitrous oxide are commonly administered. Many patients with moderate to severe ARDS will need to be intubated and placed on a ventilator to assist with their breathing. Recommended ventilator settings include limiting tidal volumes to decrease the risk of lung injury and using high positive-end expiratory pressure to keep the alveoli open.

If the patient is ventilated, prone positioning without pressure on the abdomen is important to improve lung inflation by allowing the diaphragm to move posteriorly. Judicious intravenous fluid replacement will help to replace the fluid that has leaked from the capillaries into the alveoli. If the patient has an infection such as pneumonia, they should also receive appropriate treatment.

Respiratory Trauma

Respiratory trauma occurs when the patient experiences an acute injury to the lung or surrounding area. One complication is a hemothorax, or blood in the pleural space, as well as a pneumothorax, air in the pleural space, both of which can lead to a collapsed lung. Other examples include fractured ribs and lung contusions. Flail chest, or destabilization of the chest wall, occurs when two or more contiguous rib fractures are present with two or more breaks per rib. These injuries most commonly happen as a result of falls, motor vehicle accidents, and other physical trauma.

Assessment

Symptoms of respiratory trauma vary depending on the specific trauma that has occurred, but they commonly include:

shortness of breath
pain with inhalation or chest movement
pain to palpation (if fractured ribs are present)
bruising
acute respiratory distress and hypoxia with a severe injury

In a flail chest, the injured section of the chest will visibly move during inhalation and exhalation. Lung sounds will be diminished or absent on one side if a pneumothorax or hemothorax has occurred. A chest X-ray will reveal rib fractures or a pneumo/hemothorax, while a chest CT can reveal lung contusions or more subtle injuries.

Treatment

The treatment for respiratory trauma is similar even for different injuries. Supplemental oxygen may be required for short-term use, while, in very severe injuries, intubation and ventilation may be necessary. Early ambulation, use of an incentive spirometer, and use of breathing treatments, such as a bronchodilatory DuoNeb, are all key. If the flail chest is severe, then surgical fixation of the ribs may be required. A chest tube will be placed for a large pneumo/hemothorax to allow the lung to inflate and air/blood to drain from the pleural space.

Pulmonary Hypertension

Pulmonary hypertension is elevated blood pressure in the pulmonary artery, which carries deoxygenated blood from the right side of the heart to the lungs. Over time, pulmonary hypertension can lead to right-sided heart failure as the heart works overtime to pump blood against the increased pressure in the pulmonary artery. There are two types of pulmonary hypertension: primary (idiopathic) pulmonary hypertension and secondary pulmonary hypertension. The latter can develop from vasoconstriction brought on by:

hypoxemia related to COPD and other breathing disorders
pulmonary emboli
vasculitis
interstitial lung disease
primary cardiac disease

Assessment

Symptoms of pulmonary hypertension include:

shortness of breath (especially during activity)
chest pain
fatigue
cough
lips and fingers turning blue
hoarseness
dizziness
fainting

Eventually, if right-sided heart failure occurs, the patient will experience swelling of the lower extremities and abdomen.

The diagnostic tests include a number of tests to rule out other cardiac and pulmonary conditions. These tests include:

ECG
echocardiogram (to check cardiac function and estimate the pressure in the pulmonary artery)
pulmonary function testing
six-minute walk test (to evaluate oxygen saturation during activity)
right-sided heart catheterization (to definitively measure the pressure in the pulmonary artery and check right-sided heart function)

Treatment

The treatment options for pulmonary hypertension are primarily medical. Many patients require the use of supplemental oxygen, especially during activity or at higher altitudes. Medications that are commonly utilized include:

calcium channel blockers (for systemic vasodilation)
pulmonary vascular dilators (such as IV epoprostenol [Flolan®], subcutaneous treprostinil sodium [Remodulin®], and oral bosentan [Tracleer®], all of which work to manage symptoms and prolong the survival period)
anticoagulants (to decrease the risk of pulmonary emboli)
diuretics (to reduce fluid overload, especially if right-sided heart failure occurs)

In extremely severe cases, the only treatment option may be a heart and lung transplant, a major surgery that requires long-term use of immunosuppressive drugs to prevent organ rejection.