How do you interpret arterial blood gas results for acid-base balance?

Arterial blood gas interpretation follows a systematic three-step approach. First, look at the pH: below 7.35 is acidosis, above 7.45 is alkalosis. Second, check the PaCO2 which is respiratory: if it moves in the opposite direction of the pH, the respiratory system is the cause. Normal PaCO2 is 35 to 45. Third, check the bicarbonate which is metabolic: if it moves in the same direction as the pH, the metabolic system is the cause. Normal bicarbonate is 22 to 26. Then determine if compensation is occurring by checking whether the other system is trying to normalize the pH.