When evaluating cord blood gas, if the pH is low, which other blood gas parameter helps determine if acidosis is respiratory or metabolic?

To determine whether acidosis is respiratory or metabolic when evaluating cord blood gas, examining the partial pressure of carbon dioxide (PCO2) is crucial. PCO2 indicates how well carbon dioxide is being eliminated from the body, primarily through the lungs.

In respiratory acidosis, there is an accumulation of carbon dioxide due to inadequate ventilation, leading to an increase in PCO2 and a corresponding decrease in pH. Conversely, in metabolic acidosis, the PCO2 may be normal or low as the respiratory system tries to compensate by increasing ventilation to blow off CO2.

Thus, when the pH is low, analyzing PCO2 allows healthcare professionals to distinguish between respiratory and metabolic origins of acidosis. An elevated PCO2 with a low pH suggests respiratory acidosis, while a normal or low PCO2 indicates a metabolic cause.

The other parameters, such as HCO3 (bicarbonate), also play a role in determining metabolic status but are not as direct in differentiating the type of acidosis when pH is low. The partial pressure of oxygen (PO2) relates more to oxygenation status and base excess helps assess metabolic compensation but neither specifically clarifies respiratory versus metabolic acidosis. Therefore, looking