A nurse is reviewing the laboratory results of a client who was an unrestrained passenger in a motor-vehicle crash. The ABG results are as follows: pH 7.32, HCO3 24 mEq/L, PaCO2 48 mm Hg. The nurse should identify the client is experiencing which of the following acid-base imbalances?

A) Metabolic acidosis: In metabolic acidosis, you would expect a low pH (acidosis) with a low bicarbonate (HCO3-) level. However, the given bicarbonate level is within the normal range (22-26 mEq/L), which indicates the acidosis is not metabolic in origin.

B) Metabolic alkalosis: Metabolic alkalosis would present with a high pH (alkalosis) and an elevated bicarbonate (HCO3-) level. The pH in this case is low, indicating acidosis, and the bicarbonate level is normal, ruling out metabolic alkalosis.

C) Respiratory alkalosis: In respiratory alkalosis, you would see a high pH (alkalosis) and a low PaCO2 due to hyperventilation. The given pH is low, indicating acidosis, and the PaCO2 is elevated, which is inconsistent with respiratory alkalosis.

D) Respiratory acidosis: Respiratory acidosis is characterized by a low pH (acidosis) and an elevated PaCO2 due to hypoventilation or impaired gas exchange. The client's ABG results show a low pH (7.2), a normal bicarbonate level (26 mEq/L), and an elevated PaCO2 (52 mm Hg), indicating the client is experiencing respiratory acidosis.

A) Administer dantrolene sodium IV: Dantrolene sodium is the treatment of choice for malignant hyperthermia. It acts as a muscle relaxant by inhibiting calcium release from the sarcoplasmic reticulum in skeletal muscles, which helps to halt the hypermetabolic crisis.

B) Monitor client for rapid decrease in heart rate: While monitoring vital signs is essential, a rapid decrease in heart rate is not a typical manifestation of malignant hyperthermia. The nurse should primarily focus on interventions to reduce hyperthermia and stabilize the client's condition.

C) Infuse chilled lactated Ringer's IV: Infusing chilled IV fluids can help lower the body temperature in malignant hyperthermia. However, this intervention is supportive and secondary to the administration of dantrolene sodium, which directly addresses the underlying pathophysiology.

D) Provide oxygen at 12 L/min via Venturi mask: Providing high-flow oxygen is necessary to manage hypoxia and metabolic acidosis associated with malignant hyperthermia. Nonetheless, this action is secondary to administering dantrolene sodium, which is crucial to stopping the hyperthermic crisis.