When is respiratory failure a principal or secondary diagnosis?
When the patient is admitted with acute respiratory failure (ARF) and another acute condition, both equally responsible for necessitating the admission, and when there is no chapter-specific sequencing rules, it is appropriate to code either as the principal diagnosis based on the circumstances.
For example, if the co-existing acute condition is diastolic congestive heart failure and the patient responds to immediate IV diuresis and oxygen support, the circumstances of this case suggest that ARF is a result of pulmonary volume overload. Chapter-specific coding guidelines also state that, in cases of obstetrics, poisoning, HIV, sepsis and newborns, the respiratory failure would then become a secondary diagnosis. Also, chronic respiratory failure should never be your principal diagnosis (as it is a chronic condition, not acute and not likely to necessitate an inpatient admission except in rare circumstances).