Final answer:
The patient's blood gas results suggest metabolic acidosis due to the inability of the kidneys to excrete acid by-products of metabolism, a condition that is exacerbated by acute kidney injury.
Step-by-step explanation:
The patient's blood gas results indicate metabolic acidosis: a low blood pH of 7.32, normal PaCO2 of 35 mm Hg, and decreased HCO3- levels at 18 mEq/L. Metabolic acidosis arises when there is an accumulation of acid or a loss of bicarbonate. The kidneys are responsible for excreting acid by-products of metabolism, such as hydrogen ions, and conserving bicarbonate. Acute kidney injury can lead to a dysfunction in these processes. Here, the acid-base imbalance is a result of the kidney's inability to excrete acid by-products of metabolism.
Acid-base homeostasis involves both the respiratory and renal systems. The respiratory system can quickly adjust CO2 levels, but this has a limited capacity. The kidneys handle the metabolic components by regulating bicarbonate and hydrogen ion levels, an efficient but slower process. With acute kidney injury, there is an impaired ability of the kidneys to excrete acid (hydrogen ions), often leading to an accumulation of acids in the blood (metabolic acidosis).