Info
🌱 來自: Huppert’s Notes
Approach to Analysis of an Arterial Blood Gas (ABG)🚧 施工中
Approach to Analysis of an Arterial Blood Gas (ABG)
FIGURE 3.4: Approach to interpreting arterial blood gas. Evaluation of an arterial blood gas requires a different approach based on the primary derangement, with up to four steps: 1) Evaluate pH; 2) Evaluate pCO2; 3) Evaluate anion gap and for a concomitant process (if appropriate); and 4) Check for compensation.
aNormal anion gap is patient-specific, approximated by the formula expected AG = 3x albumin (because a normal albumin is 4, normal AG is often said to be 12).
bWhen determining compensation there are several points to consider. First, the body never overcompensates, so the pH will never normalize in the absence of another primary disturbance. Second, respiratory compensation occurs more quickly based on changes in minute ventilation (RR × Vt), but metabolic compensation relies on the kidneys and therefore takes longer, resulting in the distinction between acute vs. chronic conditions.
cMetabolic acidosis compensation: Compare measured pCO2 to expected pCO2 based on Winter’s formula. If measured pCO2 is greater than expected, there is an additional respiratory acidosis. If measured pCO2 is less than expected, there is an additional respiratory alkalosis.