Q&A: Unraveling CRF types

Q: Our coding team is having trouble understanding the different types of chronic respiratory failure (CRF) and knowing when to suspect its presence when it’s not specifically documented by our physicians. Can you please help us with this?

A: CRF impacts MS-DRG assignment and risk adjustment so it’s important for coders to understand.

The problem most often arises when the provider documents the patient as having oxygen-dependent chronic obstructive pulmonary disease or oxygen dependency due to some other underlying chronic respiratory condition, but CRF is never specifically documented even though the patient is on chronic oxygen support.

So, what are the clinical indicators for the different types of CRF, and when should one suspect its presence when not specifically documented by the provider?

CRF may be of three types:

• Type 1, chronic hypoxic respiratory failure
• Type 2, chronic hypercapnic respiratory failure
• Type 3, mixed hypoxic and hypercapnic chronic respiratory failure

Criteria that supports chronic hypoxic respiratory failure is one of the following:

• Patient on room air at rest (awake when tested): Arterial oxygen saturation at or below 88% or arterial partial pressure of oxygen (PO2) at or below 55 mmHg or
• Patient on room air at rest (awake when tested): Arterial oxygen saturation of 89% or arterial PO2 of 56–59 mmHg with one of the following:
  • Dependent edema suggesting congestive heart failure
  • Pulmonary hypertension or cor pulmonale, determined by measurement of pulmonary artery pressure, gated blood pool scan, echocardiogram, or P pulmonale on EKG (P wave greater than 3 mm in standard leads II, III, or AVF)
  • Erythrocythemia with hematocrit greater than 56%

Criteria supporting type 2 or chronic hypercapnic respiratory failure are a pH below 7.38 with a partial pressure of carbon dioxide at or above 45 mmHg.

Remember, CRF is only diagnosed in a patient who has stable pulmonary gas exchange, although a previous diagnosis of CRF can coexist in a patient with acute respiratory failure. However, usually a diagnosis of CRF is not considered until at least 90 days after an acute respiratory illness as it may take that long for pulmonary gas exchange to normalize after an acute pulmonary insult.

As always, when your coding team still needs clarification, query the physician.

Editor’s note: William E. Haik, MD, FCCP, CDIP, director of DRG Review Inc., in Fort Walton Beach, Florida answered this question. Contact him at william.haik@drgreviewinc.com. Opinions expressed are that of the author and do not necessarily represent HCPro, ACDIS, or any of its subsidiaries.

This answer was provided based on limited information. Be sure to review all documentation specific to your own individual scenario before determining appropriate code assignment.

Need expert coding advice? Submit your question to editor Amanda Norris at anorris@hcpro.com and we’ll do our best to get an answer for you.