Pulmonary edema is a clinical phenomenon where fluid accumulates in the alveoli in the lungs, resulting in impaired oxygen exchange and shortness of breath. Although pulmonary edema is associated with a number of clinical problems, in the out-of-hospital environment, it is most commonly the result of congestive heart failure (CHF). Impairment of ventricular function causes blood to accumulate in both the pulmonary and systemic circulation. Pulmonary edema as a result of CHF may develop slowly, over days, or very suddenly (also known as 'flash' pulmonary edema). Treatment options for pulmonary edema depend heavily on underlying cause, so careful assessment is required.
To the maximum extent possible, paramedics and EMRs/FRs should attempt to determine the origin of the fluid and differentiate between cardiogenic pulmonary edema, asthma, pneumonia, or chronic obstructive pulmonary disease.
Consider cardiogenic shock if the patient: has a history of cardiac dysfunction; is experiencing chest pain with hypotension; has an altered level of consciousness, exhibits pale and cool skin, and/or has a decreased urine output.
Position patients to limit venous return. Be aware that many patients with pulmonary edema will be unable to tolerate a supine or semi-recumbent position. Respiratory arrest may follow if patients are forced to lie down.
Patients with impending respiratory failure (e.g., those with a respiratory rate and/or tidal volume that is decreasing and whose level of consciousness is falling) must be ventilated with a bag-valve mask (including a PEEP valve, if indicated).
Pulmonary edema is not solely caused by congestive heart failure. Exposure to toxic products (including smoke, bleach, or chlorine) can produce primary pulmonary edema due to epithelial damage. Pulmonary edema can also occur as a result of drug ingestion or submersion and drowning. These patients are generally not hypertensive, do not have a history of heart disease, and have a history of exposure. Although the in-hospital treatment of these patients is different from those with cardiogenic pulmonary edema, the principles remain the same: oxygen, supportive ventilation as required, and rapid conveyance. CPAP can be effective in these cases.
Early stage pulmonary edema may present as wheezing ('cardiac asthma'). Salbutamol may alleviate some of these symptoms, however, the wheezes in these cases are associated with airway edema rather than bronchospasm. Salbutamol has sympathomimetic properties that increase the workload of an already dysfunctional heart. The risks and benefits of salbumatmol use must be considered for each individual patient.
Diuretics are no longer considered a mainstay of out-of-hospital treatment for pulmonary edema.
Some patients with pulmonary edema will require bag-valve mask ventilation, particularly after positional changes. Paramedics and EMRs must be prepared to intervene during or immediately after a transfer and should strive to minimize patient exertion during these maneuvers.
Patients in respiratory failure, or who otherwise do not improve with CPAP, should be ventilated using a bag-valve mask. The use of positive end-expiratory pressure (PEEP) valves may be effective in improving both oxygenation and ventilation in these patients.
First Responder (FR) Interventions
Caution: Keep the patient at rest and avoid exertion during transfers. Bring equipment to the patient, including lifting and transfer devices.
Position patient sitting upright with legs dependent.
Keep the patient warm and protect from further heat loss
Identify the probable cause of the pulmonary edema
Respiratory support is the primary treatment for acute pulmonary edema but this is largely symptom relief. Specific diseases or injuries need to be addressed as the treatments will vary for the presenting clinical picture. (Cardiogenic vs non-cardiogenic)