Is there a benefit to adding cardiac Point Of Care Ultrasound (POCUS) in cardiac arrest to search for right ventricular dilation to rule out pulmonary embolism?

Cardiac POCUS During Arrest for Right Ventricular Dilation to Rule Out Pulmonary Embolism

Routine use of cardiac POCUS to search for right ventricular dilation during cardiac arrest is not recommended as the sole method to diagnose pulmonary embolism due to very low certainty evidence and potential risks of interrupting chest compressions. 1

Current Evidence and Recommendations

The 2022 International Consensus on Cardiopulmonary Resuscitation provides clear guidance on this topic:

• POCUS should not be routinely used during CPR to diagnose reversible causes of cardiac arrest (weak recommendation, very low-certainty evidence) 1
• POCUS may be considered as an additional diagnostic tool only when:
  • Performed by experienced personnel
  • Can be done without interrupting CPR
  • There is clinical suspicion for a specific reversible cause 1

Diagnostic Accuracy for Pulmonary Embolism

The evidence for using right ventricular dilation as a diagnostic indicator for pulmonary embolism during cardiac arrest is problematic:

• Only one observational study showed sensitivity of 100% (95% CI: 0.16-1.00) and specificity of 97% (95% CI: 0.82-0.99) for diagnosing PE during cardiac arrest 1
• Experts specifically caution against overinterpreting right ventricular dilation in isolation as diagnostic for massive pulmonary embolism 1
• Right ventricular dilation during cardiac arrest can occur from multiple causes, not just PE

Risks and Limitations

Several important risks must be considered:

1. Interruption of chest compressions: POCUS may increase the length of pauses in chest compressions, which is detrimental to survival 1

2. Misinterpretation: The 2020 guidelines specifically warn about "overinterpreting the finding of right-ventricular dilation in isolation as a diagnostic indicator of massive pulmonary embolism" 1

3. Verification bias: Most studies suffer from high risk of bias related to selection bias and ascertainment bias 1

4. Self-fulfilling prophecy: POCUS findings may inappropriately influence treatment decisions 2

When POCUS May Be Considered

POCUS during cardiac arrest may be considered in specific scenarios:

• When performed by experienced personnel without interrupting CPR
• When there is pre-existing clinical suspicion for PE (e.g., recent immobilization, cancer, postoperative state)
• In post-operative cardiac surgery patients who have higher pretest probability for specific causes like PE 1
• As part of a comprehensive approach to identify potentially reversible causes, not as a standalone diagnostic tool

Practical Approach

If POCUS is used during cardiac arrest to evaluate for PE:

1. Minimize interruptions: Ensure POCUS is performed during planned pulse checks or without interrupting compressions

2. Look beyond RV dilation: Consider additional findings such as:

   • McConnell's sign (RV free wall hypokinesis with apical sparing)
   • D-shaped left ventricle
   • Absence of alternative causes of arrest

3. Interpret with caution: Remember that RV dilation alone is not specific for PE during cardiac arrest

4. Consider the clinical context: Higher pretest probability (e.g., recent surgery, known DVT) increases the value of POCUS findings

Bottom Line

While POCUS has potential to identify treatable causes of cardiac arrest, the evidence does not support its routine use specifically for identifying right ventricular dilation to diagnose PE. When clinical suspicion for PE exists, POCUS should be used judiciously by experienced operators without interrupting CPR, and findings should be interpreted cautiously within the broader clinical context.