Phase II shark-fin pattern on capnography is most consistent with which condition?

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Multiple Choice

Phase II shark-fin pattern on capnography is most consistent with which condition?

The Phase II shark-fin pattern on capnography signals expiratory flow limitation from obstructive airway disease. As airways constrict, emptying becomes uneven and slower, causing the upstroke to become slurred and the plateau to take on a triangular, “shark-fin” appearance. This pattern is most consistent with lower airway constriction such as bronchospasm (as seen in asthma or COPD), where bronchial smooth muscle constriction creates ongoing expiratory obstruction. Pneumothorax or cardiac arrest typically produce different findings (often reduced or absent CO2 due to poor ventilation or perfusion), while pulmonary edema tends to alter the waveform differently, not producing the characteristic shark-fin expiratory pattern.

The Phase II shark-fin pattern on capnography signals expiratory flow limitation from obstructive airway disease. As airways constrict, emptying becomes uneven and slower, causing the upstroke to become slurred and the plateau to take on a triangular, “shark-fin” appearance. This pattern is most consistent with lower airway constriction such as bronchospasm (as seen in asthma or COPD), where bronchial smooth muscle constriction creates ongoing expiratory obstruction.

Pneumothorax or cardiac arrest typically produce different findings (often reduced or absent CO2 due to poor ventilation or perfusion), while pulmonary edema tends to alter the waveform differently, not producing the characteristic shark-fin expiratory pattern.

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