Test Complete

  • Questions
  • Score
  • Minutes
Overall Results
Total Questions
Category Results

Category: Cardiology

Topic: Advanced Cardiac Life Support

Level: Paramedic

Next Unit: Post-Cardiac Arrest Care

6 minute read

Reversible Causes - Hs and Ts

In ACLS, we are always looking for the underlying cause for the problems we confront. The Hs and Ts are a method of memorizing these few MOST COMMON AND REVERSIBLE underlying causes.

You should not only know them, but also what signs and symptoms exist and the best practices for reversing these reversible causes. No matter which of the ACLS algorithms is underway, no matter how stressful the circumstance, just remember to keep trying to solve the mystery... USE YOUR TOOLS AND JUDGEMENT TO FIND AND REVERSE THE UNDERLYING CAUSE!

If the cause of an arrest is reversible, reversing this cause may reverse the arrest! Alternately, no amount of adherence to guidelines or CPR protocol may help if a reversible cause goes un-reversed.



HYPVOLEMIA - Not enough blood volume. Evidence: Fast heart rate and narrow QRS.

►Primary Treatment: Infuse Normal Saline(NS) for volume replacement.

HYPOXIA - Not enough oxygen. Evidence: Slow heart rate.

►Primary Treatment: Ensure a patent airway and effective oxygenation.

HYDROGEN Ion Excess - Acidosis (low pH) from a buildup of hydrogen ions. Evidence: Low amplitude QRS, increased respiratory rate.

►Primary Treatment: Increase rate and depth of ventilations and consider bicarb.

HYPOKALEMIA - electrolyte imbalance - not enough potassium.

Evidence: Low amplitude T waves, presence of U wave.
►Primary Treatment: IV Magnesium.

HYPERKALEMIA - electrolyte imbalance - too much potassium. Evidence: Peaked T waves and wide QRS complex

►Primary Treatment: Consider administration of HyperK Blend: intravenous bicarbonate, calcium, and insulin given together with 50% dextrose.

HYPOTHERMIA - exposure to cold resulting in damage. Evidence: Prolonged exposure to cold, numbness, skin turgor/color change.

►Primary Treatment: Slow and even rewarming process.



TENSION PNEUMOTHORAX - Air trapped in the pleural space. Evidence: Slow heart rate, narrow QRS complexes, difficulty breathing.

►Primary Treatment: needle decompression.

CARDIAC TAMPONADE - Fluid in the sac around the heart, restricting contraction. Evidence: Hypotension with narrowed pulse pressures, jugular venous distention, and muffled heart tones.

►Primary Treatment: Delivery to ED for pericardiocentesis.

TOXINS - Your patient has been exposed to a poison or toxic substance. Evidence: Prolonged QT interval, neurological impairment.

►Primary Treatment: Depends upon exposure. Take advantage of online medical direction and local protocols to help guide your decisions.

THROMBOSIS - A blood clot has clogged an artery, cutting off distal circulation. Evidence: Fast heart rate, narrow QRS, no pulse found with CPR. 

►Primary Treatment: administration of fibrinolytics or surgical embolectomy.