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With a 1-degree Celsius change from 37°C, what qualitative changes occur in ABG during hypothermic protocol?

a. pH decreases
b. PaO₂ decreases, PaCO₂ increases
c. pH increases
d. PaO₂ increases, PaCO₂ decreases

1 Answer

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Final answer:

With a 1-degree Celsius change from 37°C during hypothermic protocol, the blood pH increases and hemoglobin affinity for oxygen drops due to a leftward shift in the oxygen-hemoglobin dissociation curve.

Step-by-step explanation:

When considering a 1-degree Celsius change from 37°C in the context of arterial blood gases (ABG) during hypothermic protocol, several qualitative changes occur. In the blood, carbon dioxide (CO₂) reacts with water to form bicarbonate (HCO₃) and hydrogen ions (H⁺). As body temperature decreases, the affinity of hemoglobin for oxygen is expected to increase. This relationship can be visualized in an oxygen-hemoglobin dissociation curve, where temperature and pH both play roles.

A lower temperature, such as in mild hypothermia, would often lead to a leftward shift in the oxygen-hemoglobin dissociation curve. This shift indicates that hemoglobin has a higher affinity for oxygen at a given partial pressure of oxygen. Consequently, this would answer option b: 'The blood pH will increase and hemoglobin affinity for oxygen will drop.' However, it is important to note that a higher pH could also result from respiratory compensation for metabolic changes associated with hypothermia, leading to an increase in pH and a decrease in PaCO₂. Therefore, the complete answer to the question would be 'With a 1-degree Celsius change from 37°C, the blood pH increases and the hemoglobin affinity for oxygen drops', which corresponds to an increase in pH and a decrease in PaCO₂.

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