Which finding on an arterial line indicates ROSC when chest compressions are not ongoing?

• A. A Palpable Pulse
• B. A Sudden ETCO2 Increase
• C. An Arterial Pulse Waveform On An Arterial Line
• D. Absence of Arterial Line Waveform

Answer: (C)

The key idea is that ROSC is confirmed by real arterial perfusion detected directly by the arterial line. When chest compressions stop, a pulsatile arterial pressure waveform appearing on the line shows that the heart is delivering blood into the arterial system with each beat. This direct, continuous signal of forward flow is the most reliable clue that circulation has resumed.

Other signs can be helpful but are less definitive in this setting. A palpable pulse is a clinical sign, but can be unreliable if the patient’s condition or monitoring setup complicates assessment. An abrupt ETCO2 rise can suggest ROSC, yet it can be influenced by ventilation or CPR artifacts. Absence of an arterial waveform clearly indicates no measurable arterial flow. So, the appearance of a regular arterial line waveform is the best evidence that ROSC has occurred when not actively performing chest compressions.