Health Information Management

Brush up on respiratory system anatomy and physiology

JustCoding News: Outpatient, February 8, 2012

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by Shelley C. Safian, PhD, CCS-P, CPC-H, CPC-I

Editor’s note: With the increased specificity required for ICD-10-CM coding, coders need a solid foundation in anatomy and physiology. To help coders prepare for the upcoming transition, we will provide an occasional article about specific anatomical locations and body parts as part of a larger series for ICD-10-CM preparation. In this month’s column, Shelley C. Safian,  PhD, CCS-P, CPC-H, CPC-I, addresses the anatomy of the respiratory system.

The respiratory system, responsible for inspiration (carrying oxygen into the body) and expiration (the expulsion of carbon dioxide), is comprised of two tracts: the upper and lower respiratory tracts.

Upper respiratory tract
The upper respiratory tract begins at the nose, followed by the nasal cavity, and paranasal sinuses, then culminates with the pharynx.

Respiration begins with the intake of air through the two nostrils (the openings of the nose). While air can be brought in through the mouth, the mouth and oral cavity are considered part of the digestive system. The air continues to flow through the nasal cavity, which is comprised of the nasal septum (bone and cartilage) and the nasal conchae (bone).

The paranasal sinuses, air-filled cavities within the skull above and behind the nose, are lined with a mucous membrane and include the maxillary, frontal, ethmoidal, and sphenoidal sinuses.

The pharynx, commonly known as the throat, begins behind the nose (the nasopharynx) and continues down behind the oral cavity (the oropharynx) to the larynx. This enables the air to travel from the nasal cavity to the larynx, where the lower respiratory tract begins.

Lower respiratory tract
The epiglottis is a flap that opens to permit air to travel into the larynx or closes to prevent food particles and liquids from traveling into the larynx and ultimately the lungs. Food particles in the lung can create severe breathing problems. The epiglottis tops the larynx, which includes the thyroid cartilage and the cricoid cartilage.

The air continues through the larynx into the trachea. At a point, approximately at the center of the chest (thoracic cavity), the trachea forks into two parts, identified as the left and right primary bronchi.

The bronchi enter the left and right lungs, respectively, and continue to branch out into smaller bronchioles. The bronchioles branch out into smaller tube-like structures called alveolar ducts that end with alveolar sacs. The sacs are surrounded by a fishnet-like network of capillaries from the pulmonary vein and artery to enable the exchange of gases (i.e., oxygen and carbon dioxide), which is the purpose of the respiratory system.

This structure is similar to the branches of a tree. The trachea is like the trunk of a tree, branching out its limbs (the bronchi). Each limb then has its branches (the bronchioles) whose twigs (the alveolar ducts) blossom with buds (the alveolar sac).

The lungs, located in the lower respiratory tract, are within the thoracic cavity and represent the largest portion of the respiratory system. The ribs form a protective cage around the lungs, meeting at the sternum in the anterior medial (front center) of the thorax. The diaphragm sits distally to the lungs.

Structure of the lungs
The lungs are composed of two hemispheres: the right lung and the left lung. The right lung is subdivided into three segments: the superior, middle, and inferior lobes. The superior lobe is located posterior to the first rib and the top of the sternum. The middle lobe is located approximately at the fifth rib. The seventh rib protects the distal end of the inferior lobe. The left lung only has two lobes: the superior and the inferior. The oblique fissure (an angular crack) separates the lobes.

The exterior surface of the lungs is covered by the visceral pleura, a lubricated membrane. This slippery fluid, contained in the intrapleural space, hinders friction between the internal surface of the ribs and the lungs when they expand after inhalation.

ICD-9-CM –What coders need to know
Coders need to understand the intimate details of the upper and lower respiratory systems to report diseases and conditions of the respiratory system (chapter 8, codes 460–519). Coders working with an ear, nose, and throat (ENT) specialist should focus on the upper tract, while coders working with a pulmonologist will focus on the lower tract.

For a patient diagnosed with acute sinusitis, the physician must document which specific sinus is infected or inflamed so the coder can report the correct required fourth digit. For example, coders would report 461.0 for acute maxillary sinusitis and 461.3 for acute sphenoidal sinusitis. Coders need the same information for chronic sinusitis.

For pneumonia, clinicians need to document the cause of the pneumonia, whether it is viral or bacterial. For example, viral pneumonia due to adenovirus (480.0) requires a different code than viral pneumonia due to SARS-associated coronavirus ( 480.3). Bacterial pneumonia due to Pseudomonas (482.1) is coded differently than Staphylococcus (482.4x), which requires a fifth digit to identify the type of Staphylococcus.

ICD-10-CM – What you need to know
Diseases of the respiratory system are listed in chapter 10 of the ICD-10-CM Manual, codes J00–J99. At this point in time, the guidelines are almost the same in ICD-10-CM as they are in ICD-9-CM with some additional guidance for the proper reporting of ventilator-associated pneumonia in ICD-10-CM.

In ICD-10-CM, coders must report a five-digit code for any type of acute sinusitis to show whether the infection is recurrent. Acute maxillary sinusitis, unspecified (J01.00) and acute recurrent maxillary sinusitis (J01.01) use different codes, so check for documentation of the condition being recurrent.

For chronic sinusitis, however, coders only need a four-digit code, but the codes again vary by location. For example, report code J32.0 for chronic maxillary sinusitis and J32.1 for chronic frontal sinusitis.
Coders need to review the notes for viral and bacterial pneumonia (J12–J15) when coding in ICD-10-CM. The notes include code first, code also, and Excludes1 notes.

Editor’s note: Shelley C. Safian, PhD, MAOM/HSM, CCS-P, CPC-H, CHA, of Safian Communications Services in Orlando, FL, is a senior assistant professor who teaches medical billing and insurance coding at Herzing University Online in Milwaukee, WI. E-mail her at

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