Final answer:
When the cardiac output is low, the ETCO₂ waveform on an ETCO₂ monitor would show a smaller or flattened waveform due to a decrease in the concentration of carbon dioxide in the exhaled breath.
Step-by-step explanation:
When the cardiac output is low, it means that the heart is pumping less blood to the body. This would result in a decrease in the amount of carbon dioxide (CO₂) being produced by the body tissues, and therefore a decrease in the CO₂ waveform seen on an ETCO₂ monitor.
The ETCO₂ waveform represents the concentration of carbon dioxide in the exhaled breath. Normally, during expiration, the concentration of CO₂ in the breath rises sharply and then gradually falls. However, when the cardiac output is low, there is less CO₂ being delivered to the lungs, resulting in a lower concentration of CO₂ in the exhaled breath and a smaller or flattened ETCO₂ waveform.
For example, a normal ETCO₂ waveform may have a sharp rise during expiration followed by a gradual decrease, while a low cardiac output ETCO₂ waveform may have a smaller rise and a more gradual decrease.