The best criterion for evaluating Mr. Potter's readiness for extubation after confirming adequate tidal volume is to measure his oxygen saturation, which will directly indicate the effectiveness of his pulmonary function.
In assessing whether Mr. Potter is ready for extubation, the criterion to continue with the evaluation would be measuring his oxygen saturation. Tidal volume alone is not sufficient to decide on extubation readiness. Oxygen saturation will provide crucial information on whether his pulmonary function is adequate to maintain appropriate oxygen levels in the blood without the assistance of a ventilator.
While heart rate, skin color, and blood pressure are important physiological parameters to monitor, they do not directly measure respiratory effectiveness as oxygen saturation does. In the context of extubation, ensuring that Mr. Potter's oxygenation status is within normal limits is paramount since inadequate oxygenation would necessitate continued ventilatory support.