Acid–Base Disorders in Critically Ill Patients Admitted to a Tertiary Care Intensive Care Unit: An Observational Study

Background: Disturbances in acid–base balance are frequently encountered in critically ill patients and often reflect the severity of the underlying illness. These abnormalities have been consistently associated with increased morbidity and mortality in intensive care units (ICUs). Objectives: To evaluate the pattern of acid–base disorders in ICU patients and to determine their association with mortality. Methods: This prospective observational study was conducted over a 12-month period in the medical ICU of a tertiary care teaching hospital in western India. One hundred adult patients admitted for more than 12 hours were included. Acid–base disorders were identified using arterial blood gas (ABG) analysis following a structured five-step interpretative approach. Acid–base and biochemical parameters were compared between survivors and non-survivors. Results: The mean age of the study population was 52.6 ± 13.36 years, with a male predominance (63%). Mixed acid–base disorders were more frequent than isolated abnormalities (61% vs 39%). Metabolic acidosis (18%) was the most common isolated disorder, while metabolic alkalosis combined with respiratory alkalosis (23%) was the most frequent mixed disorder. ARDS (28%) and sepsis (18%) were the leading primary diagnoses. Overall mortality was 35%. Non-survivors had significantly lower pH, bicarbonate, sodium, and oxygen saturation, along with higher PaCO₂, anion gap, and serum creatinine (p < 0.05). Conclusions: Acid–base disorders are highly prevalent among critically ill patients, with mixed abnormalities predominating. Significant derangements in acid–base parameters are associated with increased mortality, emphasizing the importance of early recognition and timely correction.