Arterial Blood Gas

- See:
      - Metabolic Acidosis
      - Resp. Acidosis
      - Metabolic Alkalosis
      - Resp. Alkalosis

- Decreased PaCO2:
    - if PaCOz is less than 35 mmHg and pH more than 7.45, the patient is hyperventilated and the respiratory frequency or IMV rate of the ventilator should be reduced;
    - respiratory alkalosis results in a reduced serum potassium;
         - if digitalis has been prescribed, combination of digitalis and hypokalemia can result in arrhythmias;
    - PaCO2 of < 36 mmHg & pH of < 7.36 constitute hyperventilatory response to metabolic acidosis;
         - if possible, treat underlying cause of metabolic acidosis & remeasure arterial blood gases;
         - continue steps until the PaCOz and pH are within normal limits;

- Increased PaCO2:
    - if PaCO is > 44 mmHg & pH is < 7.35, condition is hypoventilation;
    - increase frequency of IMV, & after 20 minutes remeasure ABG;
    - if response is minimal, incorrect tidal volume may have been selected;
    - increase tidal volume by 100 mL and repeat arterial blood gases

Base deficit stratifies mortality and determines therapy.

Assessing acid-base status in circulatory failure. Differences between arterial and central venous blood.

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, September 4, 2012 11:29 am