Winter's Formula to predict pCO2 Calculator


PCO2 expected : ± 2 mmHg

Respiratory compensation

Respiratory compensation is the modulation by the brainstem respiratory centers, which involves altering alveolar ventilation to try and bring the plasma pH back to its normal value (7.4) in order to keep the acid-base balance in the body. It usually occurs within minutes to hours and is much faster than renal compensation (takes several days), but has less ability to restore normal values.

Acid-base homeostasis

Acid-base homeostasis is the homeostatic regulation of the pH of the body's extracellular fluid. The proper balance between the acids and bases in the body's extracellular fluid is crucial for the normal physiology of the body and for cellular metabolism. The pH of the intracellular fluid and the extracellular fluid need to be maintained at a constant level.

Metabolic acidosis

Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: increased acid production, loss of bicarbonate, and a reduced ability of the kidneys to excrete excess acids. Metabolic acidosis can lead to acidemia, which is defined as arterial blood pH that is lower than 7.35. Acidemia and acidosis are not mutually exclusive pH and hydrogen ion concentrations also depend on the coexistence of other acid-base disorders; therefore, pH levels in people with metabolic acidosis can range from low, normal, to high.

Winter's Formula to predict pCO2 Calculator

Winter's formula is used to assess respiratory compensation when analyzing an acid-base disorder. If the actual pCO2 is lower than the expected value, the patient has primary respiratory alkalosis. If the pCO2 is higher than the expected value, the patient has primary respiratory acidosis.