Winter's formula and Henderson-Hasselbalch equation

Purpose of winter’s

To evaluate respiratory compensation (use of lungs) for METABOLIC ACIDOSIS ONLY to give expected value for patients PCO2 to assess if the patient is compensating their acidotic state.

Formula of winter’s

PCO2 = (HCO3 × 1.5) + 8±2. Uses patient’s bicarbonate levels to help calculate what the appropriate respiratory compensation should be.

Difference b/w Winter’s formula and H-H equation

Winter’s = metabolic acidosis ONLY and is compensated by lowering CO2 to increase pH

H-H’s = originally presented to explain pH, modified to double check ABG and modified to target pH, bicarb, or PaCO2

BOTH = help drive respiratory compensation for a patient on a ventilator.

function of H-H

Mathematically illustrates how the pH of a solution is influenced by the bicarb to H2CO3 ratio (base:acid). It illustrates the relationship b/w pH and bicarb and H2CO3 and is used to confirm 20:1 ratio and a 7.4 pH in normal conditions.

formula of H-H equation

pH = pK + log HCO3-/H2CO3, with pK being 6:1 and a normal base:acid being 20:1. If ratio changes, pH changes. Can be used to calculate when any two of three values are known: pH, HCO3-, and/or PaCO2 and cross-checks the validity of a blood gas to estimate.