Which option best describes a key metric used to assess the effectiveness of CPR?

• A. Ventilation rate.
• B. Oxygen saturation.
• C. Defibrillation timing.
• D. Chest compression fraction.

Answer: (D)

Maintaining continuous chest compressions to keep blood flow during CPR is the central idea. Chest compression fraction is the measure that quantifies how much of the resuscitation time is spent actually delivering compressions. A higher fraction means fewer or shorter pauses, which keeps coronary and cerebral perfusion pressures higher and improves the likelihood of return of spontaneous circulation and better survival.

Why this metric stands out: interruptions during CPR sharply reduce blood flow. If compressions are paused for ventilations, rhythm checks, or defibrillation, perfusion drops and the effectiveness of resuscitation decreases. Chest compression fraction captures exactly how much of the time you’re sustaining compressions, making it a direct reflection of CPR quality in real time.

Ventilation rate matters for oxygen delivery, but it doesn’t tell you how well CPR is sustaining blood flow. Oxygen saturation reflects blood oxygenation after some delay and depends on multiple factors beyond the immediate quality of chest compressions. Defibrillation timing is crucial for shockable rhythms, but it is an action within resuscitation rather than a measure of ongoing CPR effectiveness.

In pediatric practice, aiming for a high chest compression fraction reinforces continuous perfusion and is associated with better outcomes, so it’s the most informative single metric for assessing CPR effectiveness during the event.