August 2011
HYPOXEMIA/HYPOXIA DIAGNOSIS CODING
Diagnosis Coding of Hypoxemia/Hypoxia
Hypoxemia is defined as insufficient levels of oxygen in the blood, while hypoxia is defined as
insufficient levels of oxygen in other organs.1 This diminished availability of oxygen can be caused by
intrinsic factors, such as pulmonary disorders (chronic obstructive pulmonary disease), circulatory
disorders (hypotension), and blood disorders (anemia), or extrinsic factors such as deficiency of
oxygen in the atmosphere. 2
The ICD-9 manual states that codes which describe symptoms and signs, as opposed to diagnoses,
are acceptable for reporting purposes when a related definitive diagnosis has not been established by
the provider.2 The diagnosis code for hypoxemia/hypoxia is located in the ICD-9 manual, Chapter 16
- Symptoms, Signs, and Ill-Defined Conditions, which is subdivided into three sections: a) symptoms,
b) nonspecific abnormal findings, and c) ill-defined and unknown causes of morbidity and mortality.
The code for hypoxemia/hypoxia, 799.02, is located within section c. This supports the idea that
hypoxemia/hypoxia is not a symptom, but rather a potential cause, or condition, that in itself affects
morbidity and mortality.3
Further, the American Hospital Association coding clinics have stated that hypoxemia/hypoxia should
be coded as an additional diagnosis unless it’s inherent to the primary diagnosis. These coding clinics
have clearly illustrated that hypoxemia/hypoxia can be coded separately from many respiratory
diagnoses such as COPD4, pneumonia5, and asphyxia,6 but is inherent in a diagnosis of respiratory
failure7 and should not be coded separately in the last situation. In support of this rationale, the
definition of COPD, for example, states that it’s a condition that creates difficulty with moving air in
and out of the lungs, but does not necessarily cause difficulty with moving oxygen into the blood
stream itself.8 However, the description of respiratory failure states that the defining characteristic of
the disorder, in the majority of cases, is an inability of the lungs to properly oxygenate the blood,
which is hypoxemia, and supports the coding clinic’s guidelines for not coding hypoxemia/hypoxia as
a separate condition from respiratory failure.9
Due to the various factors that can cause hypoxemia/hypoxia and the fact that the medical resources
indicate that it’s a separate condition in most situations, the decision to code hypoxia should be based
on whether it is inherent to another existing disease. If it’s not clearly discernible from the
documentation, the coder should clarify with the provider.
Sources:
(1) Hypoxemia vs. Hypoxia, Buzzle.com/articles/hypoxemia-vs-hypoxia.html
(2) Hypoxia, The Free Dictionary online
(3) The 2011 ICD-9-CM coding manual
(4) Hypoxia and chronic obstructive pulmonary disease, Coding Clinic, 3rd quarter 2009, p 20
(5) Hypoxemia with pneumonia, Coding Clinic, 2nd quarter 2006, p 24
(6) Hypoxemia and asphyxia, Coding Clinic, 4th quarter 2005, p 90
(7) Hypoxemia with acute respiratory failure, Coding Clinic, 2nd quarter 2006, p 25
(8) Respiratory Failure, National Heart and Lung Institute, Diseases and Conditions Index
(9) Respiratory Failure, emedicine.medscape.com
This information is provided to assist you in the correct coding of diagnoses and conditions commonly seen within your practice. It is not
meant to replace or supersede information provided within the ICD-9-CM Manual. When in doubt, please refer to the ICD-9 manual and
related AHA Coding Clinics.
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