Q&A: Sequencing acute respiratory failure and its etiology

Q: I’ve been told that acute respiratory failure always has an underlying etiology, would that issue be listed as the primary diagnosis?

A: There is a difference between the term primary diagnosis and principal diagnosis, although many use these terms interchangeably.

The primary diagnosis is the condition that requires the most resources and care, while the principal diagnosis is the condition that causes the patient to be admitted to a hospital or other care facility. In most cases, the primary and principal diagnoses are the same. The purpose of the principal diagnosis is to establish what condition, after study, occasioned the admission.

The purpose of the primary diagnosis is to establish where doctors focus the majority of their resources to treat a condition. The primary diagnosis is not always the principal diagnosis because patients admitted to the hospital with multiple comorbidities require treatment for all the conditions, but not every condition fits the definition of principal diagnosis.

For example, look at the patient who is admitted to inpatient status for a bowel resection related to colon cancer. In this case, the colon cancer is the principal diagnosis, the diagnosis that occasioned the admission. But when we review the record, we find that due to a myocardial infarction (MI) prior to the start of the surgery, the procedure is cancelled, and the patient is sent to the catheter lab for a percutaneous transluminal coronary angioplasty (PTCA).

In this instance, the resources applied for the encounter were toward the MI and therefore the MI would be identified as the primary diagnosis. The colon cancer, however, remains the principal diagnosis as it was the condition that occasioned the admission to the hospital. The Official Guidelines for Coding and Reporting, Section II F, supports this sequencing.

Now, your question asks about sequencing the etiology of the respiratory failure first when establishing the principal diagnosis. Much of the confusion over the years regarding this issue stems from changing recommendations from the American Hospital Association (AHA) Coding Clinic instructions. Currently, the direction states that either the acute respiratory failure or the established etiology can be sequenced first; however, we must take the circumstances of the encounter into account.

Many cite the coding convention related to etiology/manifestation as dictating that the etiology must be sequenced first. This convention under certain conditions directs the coder to “code first the underlying condition.”

So, to confirm whether the convention applies to acute respiratory failure, look in the code book to see if this “code first” note is listed under the code grouping for acute respiratory failure. And, you can see, there is no such sequencing instruction.

Editor’s Note: Laurie L. Prescott, RN, MSN, CCDS, CDIP, CRC, CDI education director at HCPro in Middleton, Massachusetts, answered this question. Contact her at lprescott@hcpro.com. For information regarding CDI Boot Camps, click here.