A patient with depressed ventilation secondary to a drug overdose will have what change in his pH?

Question

A patient with depressed ventilation secondary to a drug overdose will have what change in his pH? What acid/base imbalance will be present?

Answer 1

The pH will go down, because he'll have respiratory acidosis secondary to his failure to breathe adequately and rid his body of CO2.

Answer 2

It drops. Ph goes down as pCO2 goes up in respiratory failure.

Answer 3

Well, it depends on what the drug was.  For example, if it was a tricyclic antidepressant .... an arterial or venous blood sample should be sent to assess plasma pH. Cyclic antidepressant (CA) toxicity usually results in mixed acidosis due to respiratory depression coupled with hypotension caused by both myocardial depression and peripheral vasodilation, thus resulting in increased lactate production. Acidemia decreases protein binding and increases plasma levels of free drug. Therefore, correction of serum pH is a primary target of therapy in CA overdose.