Epidemiology + Pathophysiology
- CHF exacerbation is a common issue that is encountered by EMS
- Approximately 5 million Americans have congestive heart failure
- It is the most common reason for hospitalization for patients over the age of 65
- Nearly 50% of patients diagnosed with CHF will die within 5 years
- Congestive Heart Failure is the heart’s inability to adequately pump and meet the body’s demand.
- Heart Failure can be divided up into two types:
Right and Left Heart Failure
|Right Sided Heart Failure||Left Sided Heart Failure|
|Inadequate contraction of the right atrium and ventricle|
Causes decreased forward flow to the lungs
Causes backup of blood in the venous system
Signs: peripheral edema (arms and legs swelling), ascites (abdominal swelling) and JVD
Most common cause of right sided failure is left sided heart failure
|Inadequate contraction of the left atrium and ventricle|
Causes decreased forward flow to the systemic arterial vasculature
Causes backup of blood in the pulmonary vasculature
Primary sign of left sided heart failure is pulmonary edema
PRIMARY ISSUE SEEN IN THE PREHOSPITAL SETTING!
- As forward flow is disrupted, plasma starts to build up in the vasculature thus increasing the hydrostatic pressure within the capillary beds. This eventually leads to edema in the respective third spaces depending on the side the heart failure is occurring
- Remember that a patient can have pulmonary edema without any evidence of peripheral edema, ascites or JVD. Listen to lung sounds
- Congestive heart failure (CHF) is the disease process. The medical emergency is typically cardiogenic pulmonary edema. In the case of CHF induced cardiogenic pulmonary edema, successful treatment is completely dependent on helping the heart.
Management + Clinical Goals
- The primary goal in cardiogenic pulmonary edema is to reduce preload and reduce afterload.
- What is Preload and Afterload?
- Preload- The volume of blood that is pumped into the ventricle. Largely dependent on the venous return to the heart.
- Afterload- The resistance of the systemic vasculature that the heart has to pump against.
- It has been found that high dose Nitroglycerin (100-150 mcg/min) can achieve both a reduction in preload and afterload.
- In the prehospital setting, sublingual Nitroglycerin at 0.4mg given every 4 minutes satisfies this by averaging to a dose of 100 mcg/min
- CPAP is a great method of improving oxygenation in the patient with cardiogenic pulmonary edema.
- CPAP works by adding PEEP to the equation. PEEP- Positive End Expiratory Pressure works by increasing the surface area of alveoli available for gas exchange. This allows higher concentration of O2 to make it into the blood and CO2 to be offloaded.
- Here are indications and contraindications for the use of CPAP:
|Low SpO2 (less than 90%) refractory to supplemental oxygen|
Dyspnea with an inability to speak full sentences
Use of accessory muscles
|Hypotension (BP less than 90mmHg) due to the possibility of increased intrathoracic pressure|
Altered level of consciousness where patient cannot follow commands
Suspicion of pneumothorax
Inability to get an appropriately fitting mask
- To apply CPAP– Size the mask, set up per manufacturer recommendation, coach patient through the procedure, start with a PEEP of 5 cmH20 and move up as needed based on SpO2, be cautious with high levels of PEEP and watch for hypotension.