The Secondary Assessment

The secondary assessment emphasizes focused medical history taking to identify and treat possible causes of cardiac arrest. A useful mnemonic to perform a focused history is SAMPLE:

• Signs and symptoms
• Allergies
• Medications (amount and timing of the last dose)
• Past medical history
• Last meal consumed
• Events – circumstances surrounding the event

During the secondary assessment, the responder should evaluate the Hs and Ts—the most common reversible causes of cardiac arrest. Promptly treating these conditions may increase the probability of achieving ROSC.

Related Video: Understanding the Secondary Assessment Steps

Related Video: Introduction to the Hs and Ts

Hs and Ts

Short Description

This graphic provides the potential causes, assessments and findings, and treatments and interventions for each of the Hs and Ts or reversible causes of cardiac arrest.

Graphic at a Glance

• The team accurately identifies potential causes of cardiac arrest.
• When caring for a specific patient, the team understands the assessment, findings, and symptoms for each cause.
• The team understands the appropriate treatments and interventions for each of the reversible causes of cardiac arrest.

Goals for the Identification of Hs and Ts

The team will be able to:

• Identify the potentially reversible causes of cardiac arrest (the Hs and Ts)
• Understand the assessments and findings associated with each cause
• List the interventions for each of the findings

The Hs and Ts

Each member of the resuscitation team understands the possible reversible causes of cardiac arrest, including how to assess for and treat each cause.

Most Common Reversible Cardiac Arrest Causes

These reversible causes are referred to as the Hs and Ts, and they include:

• Hypovolemia: This is typically caused by bleeding or other fluid loss and is corrected by the administration of fluid or blood.
• Hypoxia:  Hypoxia is often caused by medications or other poisonings or drowning and can be corrected by assisted ventilation, oxygenation, and high-quality CPR as needed.
• Hydrogen ion excess (acidosis): Acidosis can be caused by respiratory or metabolic issues, renal failure, or drug overdoses and must be corrected by correcting the underlying abnormality. In severe cases, the clinician can consider the administration of sodium bicarbonate.
• Hypo/Hyperkalemia: Fluctuations in potassium levels can be caused by renal failure, crush injuries, or nausea and vomiting. In the case of a potassium deficit, the electrolyte must be replaced. When there is too much potassium, the clinician must consider the administration of calcium chloride, glucose with insulin, or sodium bicarbonate.
• Hypothermia: Exposure to cold environments is the primary cause of hypothermia. Immediate treatment includes rewarming until the core temperature is above 86°F (30°C).
• Tension pneumothorax: One of the most common causes of tension pneumothorax is positive pressure ventilation. Others include trauma, asthma, and COPD. Emergency treatment includes needle decompression. If a chest tube setup is immediately available, that is the treatment of choice.
• Tamponade (cardiac): Although there can be many causes for cardiac tamponade, the most common in a resuscitation scenario are trauma and cardiac compressions. Treatments include fluid administration, pericardiocentesis, or thoracotomy.
• Thrombosis (coronary): A STEMI is the result of coronary thrombosis. The clinician follows the treatment algorithm to include the administration of fibrinolytics or PCI therapy in the cardiac catheterization lab.
• Thrombosis (pulmonary): Acute MI can also cause pulmonary thrombosis. Therapy includes volume administration, medications, fibrinolytic therapy, and surgical pulmonary thrombectomy.
• Toxins: Medications, street drugs, toxins/chemicals, or environmental exposure can lead to cardiac arrest. In this case, the clinician administers the antidote based on the particular toxin while supporting systemic function.