American College of Physicians: Internal Medicine — Doctors for Adults ®


Chronic respiratory failure

From the March ACP Hospitalist, copyright © 2011 by the American College of Physicians

By Richard D. Pinson, FACP

Chronic respiratory failure is usually recognized by a combination of chronic hypoxemia, hypercapnea and compensatory metabolic alkalosis (elevated bicarbonate levels). Whenever a patient's medical problems include this condition, it is very important to document it in the medical record, as chronic respiratory failure contributes significantly to the severity level, complexity and costs of care.

Many patients with severe or long-standing chronic obstructive pulmonary disease (COPD) also have chronic respiratory failure. If a patient is admitted for an acute exacerbation of COPD, always look for findings consistent with chronic respiratory failure. Typically patients with chronic respiratory failure require supplemental home oxygen therapy, so the diagnosis should be strongly considered for any patient using home oxygen.

Photo by Comstock.

Photo by Comstock.

In pure chronic respiratory failure, the pH value on arterial blood gases will be normal (7.35-7.45). Any degree of respiratory acidosis or worsening of respiratory symptoms indicates that acute respiratory failure is now superimposed on the chronic state. The appropriate diagnostic term for this circumstance is “acute on chronic respiratory failure”—a very important distinction to make since the acute state represents a much more serious condition.

Even if the patient's chronic respiratory failure is stable, unchanged or at baseline, however, it should be documented in the medical record as a significant comorbid condition that needs to be coded.

Richard D. Pinson, FACP, is a certified coding specialist and co-founder of HCQ Consulting in Houston. This content is adapted with permission from HCQ Consulting.



Ask Dr. Pinson

Q: I frequently have patients admitted to the ICU with a diagnosis of drug overdose, respiratory failure, endotracheal intubation, etc. Many patients are stabilized quickly and discharged for psychiatric management in 24 to 48 hours. Other patients are admitted with a diagnosis of acute on chronic congestive heart failure and have a quick response to Lasix, followed by discharge in 24 to 48 hours.

In these cases, the hospital wants to bill for an inpatient DRG, given the admitting diagnosis and severity of illness. The payer argues that even though the patient meets inpatient criteria, it will only pay for an observation level of care because the patient was stabilized and discharged within 24 to 48 hours. According to the payer, there is a contract with the hospital that provides for payment as observation only (not as an inpatient DRG) when there is such a short stay.

I have frequently been asked to do peer-to-peer review with the payer's medical director. What is correct? If the patient met inpatient criteria but got better and was discharged in 24 to 48 hours, should the hospital get paid for an inpatient DRG or for observation?

A: This is a very important and interesting question. The answer is: It all depends on the contract!

Let's begin with Medicare, where there is no contract. Medicare regulations require the attending physician and hospital to determine medical necessity. If inpatient medical necessity criteria (such as InterQual or Milliman criteria) are met, the patient should be admitted and billed as an inpatient DRG. This decision may be subject to subsequent review and redetermination by Medicare Administrative Contractors (MACs) or Recovery Audit Contractors (RACs).

The situation with Medicaid depends on state regulations, which can be highly variable. Some states define outpatient observation as any patient who is admitted for less than 24 to 48 hours. Some rely on inpatient medical necessity criteria. Some pay an outpatient observation rate vs. inpatient rate, either by DRG or per diem (“by the day”); others do not pay for any outpatient observation at all. Medicaid payments may also be subject to further review or audits.

Payments by commercial payers (like Blue Cross, Aetna, Cigna, Humana and United Health Care) depend entirely upon the provisions of the contract between the hospital and the insurance company. The choice between observation and inpatient is usually made before the patient is discharged, but can be subject to retrospective review. To determine the provisions for inpatient medical necessity and payment, one would need a copy of each payer contract.

In many cases, hospital management does not know what the specific provisions are for inpatient vs. outpatient observation criteria. It may become necessary for the hospital to renegotiate these terms whenever a problem with payment arises.

Got a documentation or coding conundrum? Each month, Dr. Pinson will respond to selected questions from readers. Please e-mail your questions.



In the Coding Corner column in the November 2010 ACP Hospitalist, the description of acute tubular necrosis (ATN) contained imprecise information. Contrary to what was written, ATN is more common among inpatients than is usually thought, occurring in one-third or more of acute renal failure (ARF) cases.

ATN often results from progression of “pre-renal” ARF caused by volume depletion, dehydration, hypotension, or edematous states. ATN is most often associated with hypotension, especially when severe, and it is the usual cause of acute renal failure associated with toxins or drugs, including IV radio-contrast material.

ATN can be distinguished from “pre-renal” ARF by the response to effective fluid administration and rehydration. With ATN, it usually takes more than 72 hours for renal function to return to baseline; with ARF, it takes less than 72 hours. Urine sediment often shows “muddy brown” casts and tubular cells with ATN, but red blood cells (RBCs) or white blood cells (WBCs) would not be expected. Urinary sodium concentration is typically >40 meq/L, and the fractional excretion of sodium (FENa) is >2%.

It is very important to recognize and document ATN when it occurs because it represents a more severe degree of acute renal failure and contributes significantly to the complexity and cost of patient care. Remember that the term “pre-renal azotemia” should not be used to describe “pre-renal” ARF since it will not be assigned the correct code for acute renal failure.

—Richard D. Pinson, FACP


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