FCM Critical Care Practice Exam 2026 – Comprehensive Preparation Resource

A decrease in HCO3- (bicarbonate) levels indicates acidosis when interpreting arterial blood gas (ABG) results. Bicarbonate is a crucial buffer in the body’s pH balance, and it helps in neutralizing acidity. When HCO3- levels drop, it suggests that there is either an accumulation of acids in the body or a loss of bicarbonate, both of which could lead to a more acidic environment.

Acidosis can result from various conditions, such as metabolic acidosis, where there is an increased production of acids (e.g., lactic acid) or renal failure (where the kidneys cannot excrete acids effectively) or from a loss of bicarbonate (e.g., diarrhea). In the context of ABGs, a decreased HCO3- level typically accompanies a low pH, confirming the presence of acidosis. Understanding this relationship is vital for diagnosing and managing critical care patients effectively.