Pulmonary edema is a condition that occurs due to the accumulation of fluid in the lungs within the interstitial space and alveoli. This accumulation impairs gas exchange in the alveoli, leading to reduced oxygenation of the blood and, in some cases, the buildup of carbon dioxide. It is most commonly caused by acute heart failure and can be fatal.

In the pathophysiology of pulmonary edema, three factors are discussed:

1. Flow
2. Fluid
3. Filter

Flow – The ability of the heart as a pump depends on three factors:

• The volume of blood returning to the heart (volumetric loading – preload)
• Coordinated myocardial contraction
• Systemic resistance against which the heart pumps blood (pressure loading – afterload) Volumetric loading can increase due to excessive IV fluid infusion or fluid retention resulting from renal failure. Coordinated contraction is compromised after damage to the cardiac muscle (myocardial infarction, heart failure) or due to arrhythmias. Pressure loading increases due to hypertension, atherosclerosis, aortic valve stenosis, or peripheral vasoconstriction.

Fluid – Blood passing through the lungs must have sufficient oncotic pressure to retain fluid as it passes through the pulmonary capillaries. Since albumin is a key determinant of oncotic pressure, conditions with low albumin can lead to pulmonary edema, e.g., burns, liver failure, nephrotic syndrome.

Filter – The permeability of capillaries through which fluid passes can increase, e.g., in cases of acute lung injury (such as smoke inhalation), pneumonia, or drowning.

The most common cause of pulmonary edema that prompts an emergency medical team call is acute heart failure.

The overall prevalence of heart failure ranges from 1% to 2% and varies with age. Among these patients, 80% are diagnosed after hospital admission. Approximately 30% of them will be readmitted to the hospital every year.

Signs and symptoms of pulmonary edema can be difficult to distinguish from other causes of dyspnea, such as exacerbation of chronic obstructive pulmonary disease (COPD), pulmonary embolism, or pneumonia. Therefore, a detailed medical history and physical examination are necessary. Compared to hospital diagnoses, the accuracy of acute left ventricular failure assessment by the emergency medical team is between 77% and 89%.

MEDICAL HISTORY

Symptoms: Dyspnea Worsening cough (productive, white sputum) Pink, frothy sputum Nocturnal dyspnea Nocturnal cough Orthopnea (recently needing more pillows to sleep?) Anxiety/restlessness Symptoms of pulmonary edema may be associated with: Ankle edema Chest pain Exacerbation of angina pectoris Past medical history: Admission for “heart failure,” fluid in the legs/lungs Prior myocardial infarction/angina pectoris/angioplasty/coronary artery bypass grafting Diabetes Hypertension Current medications: Home oxygen ACE inhibitors Beta-blockers Diuretics Antiarrhythmics Other risk factors for heart disease: Smoking Family history High cholesterol Diabetes

ASSESSMENT

• Ensure the safety of the scene and apply personal protective measures.
• Notify T1 if necessary.
• Perform an initial assessment following the ABCDE approach.
• If the patient’s condition allows, take a 12-lead EKG.

Pay special attention to:

• Excessive sweating or cold, moist skin.
• Carotid pulse (rate, rhythm) – tachycardia is common.
• Blood pressure can be high (>170/100) or low.
• Elevated pressure in the jugular veins.
• Central cyanosis.

Chest examination:

• Rate and effort of breathing.
• Use of accessory muscles.
• Fine crackles heard above the lung bases during inspiration.
• Wheezes.
• Rhonchi (whistling sounds) may indicate asthma or pulmonary edema.

Evaluate factors where TIME IS CRITICAL:

• Severe dyspnea.
• Central cyanosis.
• Hypoxia, i.e., oxygen saturation <94% unresponsive to supplemental oxygen.
• Exhaustion.
• Altered consciousness.
• Systolic blood pressure <90 mmHg or tachycardia where the number of beats per minute numerically exceeds the measured systolic blood pressure (mmHg).

TREATMENT

• Follow guidelines for medical emergencies.
• Initiate care according to ABCDE.
• Have the patient sit upright.
• Administer oxygen (target saturation >94%).
• Monitor blood oxygen saturation with a pulse oximeter.
• Monitor partial pressure of CO2 in exhaled air at the end of expiration using capnometry/capnography.
• Maintain continuous cardiac rhythm monitoring.
• Administer assisted breathing and intubation in a rapid sequence if:
  • Respiratory rate is <10 or >30 per minute.
  • Inadequate chest expansion.
• Transport the patient to the hospital and continue care during transport.
• Document all observations, measurements, and procedures.
• Notify the hospital of the patient’s arrival if necessary.

Prepare equipment for cardiopulmonary resuscitation.

NOTE: A 12-lead EKG should be performed during the patient examination. A significant portion of patients with pulmonary edema have acute myocardial infarction as the underlying cause. If there is suspicion of this, the guidelines for acute coronary syndrome should be followed. If the cause of pulmonary edema is a rhythm disturbance, the guidelines for treating that specific rhythm disturbance should be followed.

SUMMARY

• Pulmonary edema can be difficult to distinguish from other causes of dyspnea, such as exacerbation of COPD, pulmonary embolism, or pneumonia, so a detailed medical history and physical examination are crucial.
• Symptoms include dyspnea, worsening cough, pink frothy sputum, nocturnal cough, orthopnea, and anxiety/restlessness.
• The patient should be seated upright.
• Early administration of oxygen is crucial in treatment.
• Prepare equipment for cardiopulmonary resuscitation.