Chapter 10 — Diseases of the Respiratory System
Acute respiratory failure sequencing, confirmed-influenza coding, ventilator associated pneumonia and vaping-related disorders — plus what an acute exacerbation actually is.
Chapter 10 covers COPD and asthma exacerbation, acute respiratory failure sequencing, confirmed-influenza coding, ventilator associated pneumonia and vaping-related disorders. The hardest of these is acute respiratory failure: it may be a principal diagnosis, and whether it is depends entirely on the circumstances of admission rather than on any fixed rule.
COPD and asthma — what is an acute exacerbation?#
| Point | Rule |
|---|---|
| Categories | J44 and J45 distinguish between uncomplicated cases and those in acute exacerbation |
| Definition | An acute exacerbation is a worsening or a decompensation of a chronic condition |
| What it is not | NEVER An acute exacerbation is not equivalent to an infection superimposed on a chronic condition — though an exacerbation may be triggered by an infection |
Acute respiratory failure — principal or secondary?#
| Situation | Rule |
|---|---|
| As principal diagnosis | A code from J96.0- acute respiratory failure, or J96.2- acute and chronic respiratory failure, may be assigned as a principal diagnosis when it is the condition established after study to be chiefly responsible for occasioning the admission, and the selection is supported by the Alphabetic Index and Tabular List |
| The overriding constraint | Chapter-specific coding guidelines that provide sequencing direction — obstetrics, poisoning, HIV, newborn — take precedence |
| As secondary diagnosis | Where respiratory failure occurs after admission, or is present on admission but does not meet the definition of principal diagnosis |
| Respiratory failure and another acute condition — MI, CVA, aspiration pneumonia | The principal diagnosis will not be the same in every situation. This applies whether the other acute condition is respiratory or nonrespiratory. Selection depends on the circumstances of admission |
| Both equally responsible for the admission, with no chapter-specific sequencing rule | The guideline regarding two or more diagnoses that equally meet the definition for principal diagnosis — Section II.C — may be applied |
| Documentation unclear as to whether they are equally responsible | QUERY Query the provider for clarification |
Influenza — code only confirmed cases#
| Documentation | Category | Notes |
|---|---|---|
| Avian influenza or other novel influenza A, confirmed | J09 | Confirmation does not require positive laboratory testing specific for avian or other novel influenza A. Coding is based on the provider's diagnostic statement. An exception to Section II.H |
| Another particular identified strain such as H1N1 or H3N2, not identified as novel or variant, confirmed | J10 | Same confirmation standard |
| “Suspected”, “possible” or “probable” avian, novel or other identified influenza | J11 | NEVER Do not assign a code from J09 or from J10. Assign the appropriate code from J11, influenza due to unidentified influenza virus |
Ventilator associated pneumonia#
| Situation | Rule |
|---|---|
When J95.851 may be assigned | Only when the provider has documented ventilator associated pneumonia. As with all procedural or postprocedural complications, code assignment is based on the provider's documentation of the relationship between the condition and the procedure |
| Organism | Assign an additional code to identify the organism — for example Pseudomonas aeruginosa, B96.5 |
| Type of pneumonia | NEVER Do not assign an additional code from J12–J18 to identify the type of pneumonia |
| Pneumonia in a ventilated patient without a VAP statement | NEVER J95.851 is not assigned. If the documentation is unclear as to whether the pneumonia is a complication attributable to the mechanical ventilator, QUERY query the provider |
| VAP that develops after admission in a patient admitted with a different pneumonia | The principal diagnosis is the appropriate code from J12–J18 for the pneumonia diagnosed at the time of admission. J95.851 is assigned as an additional diagnosis where the provider has also documented VAP |
Vaping-related disorders#
| Situation | Assign |
|---|---|
| A patient presents with any condition related to vaping | U07.0 Vaping-related disorder, as the principal diagnosis |
| Lung injury due to vaping | Only U07.0 |
| Other manifestations | Additional codes, such as J96.0- acute respiratory failure or J68.0 pneumonitis |
| Associated respiratory signs and symptoms due to vaping — cough, shortness of breath | NEVER Not coded separately when a definitive diagnosis has been established |
| Gastrointestinal symptoms such as diarrhoea and abdominal pain | ALWAYS Appropriate to code separately |
Practice questions#
Q1A patient on a ventilator for three days develops pneumonia. The provider documents “pneumonia” but does not state that it is ventilator-associated. What is assigned?
- A
J95.851and an organism code - BThe appropriate pneumonia code from
J12-J18; query the provider about the relationship to the ventilator - C
J95.851alone - D
J95.851plus a code fromJ12-J18
Show answer & rationale
Correct answer: B. The appropriate pneumonia code from J12-J18; query the provider about the relationship to the ventilator
Rationale. Guideline I.C.10.d.1 states that J95.851 should not be assigned for cases where the patient has pneumonia and is on a mechanical ventilator but the provider has not specifically stated that the pneumonia is ventilator-associated, and that if the documentation is unclear as to whether the pneumonia is a complication attributable to the mechanical ventilator, the provider should be queried. Code assignment for any postprocedural complication rests on the provider's documentation of the relationship.
Q2The provider documents “probable H1N1 influenza”. What is assigned?
- AA code from
J10 - BA code from
J09 - CA code from
J11 - DNo influenza code at all
Show answer & rationale
Correct answer: C. A code from J11
Rationale. Guideline I.C.10.c states that only confirmed cases of influenza due to certain identified influenza viruses (J09) and due to other identified influenza virus (J10) are coded, that this is an exception to the inpatient uncertain-diagnosis guideline, and that if the provider records suspected, possible or probable avian, novel or other identified influenza, the appropriate code from category J11, influenza due to unidentified influenza virus, should be assigned instead.
Q3A patient presents with lung injury due to vaping. What is assigned?
- A
J68.0alone - B
U07.0alone - C
U07.0andJ68.0 - D
J68.0withU07.0as a secondary code
Show answer & rationale
Correct answer: B. U07.0 alone
Rationale. Guideline I.C.10.e states that for patients presenting with conditions related to vaping, U07.0 is assigned as the principal diagnosis, and that for lung injury due to vaping, only code U07.0 is assigned. Additional codes are assigned for other manifestations such as acute respiratory failure or pneumonitis — but lung injury itself is covered by U07.0.
Q4A patient is admitted with both acute respiratory failure and an acute myocardial infarction, and the record does not make clear which occasioned the admission. What is the correct action?
- AAlways sequence the respiratory failure first
- BAlways sequence the myocardial infarction first
- CQuery the provider for clarification
- DAssign the respiratory failure as a secondary diagnosis automatically
Show answer & rationale
Correct answer: C. Query the provider for clarification
Rationale. Guideline I.C.10.b.3 states that when a patient is admitted with respiratory failure and another acute condition the principal diagnosis will not be the same in every situation, that selection depends on the circumstances of admission, that where both are equally responsible and there are no chapter-specific sequencing rules Section II.C may be applied, and that if the documentation is not clear as to whether they are equally responsible, the provider should be queried.
Q5Which statement about acute exacerbation of COPD reflects the FY 2027 guideline?
- AAn acute exacerbation is the same as an infection superimposed on COPD
- BAn acute exacerbation is a worsening or decompensation of a chronic condition, and is not equivalent to a superimposed infection
- CAn exacerbation can never be triggered by an infection
- DExacerbation codes are only available in category
J45
Show answer & rationale
Correct answer: B. An acute exacerbation is a worsening or decompensation of a chronic condition, and is not equivalent to a superimposed infection
Rationale. Guideline I.C.10.a.1 states that the codes in categories J44 and J45 distinguish between uncomplicated cases and those in acute exacerbation, that an acute exacerbation is a worsening or a decompensation of a chronic condition, and that an acute exacerbation is not equivalent to an infection superimposed on a chronic condition — though an exacerbation may be triggered by an infection.
Scenarios#
A patient with end-stage COPD is admitted from home in acute hypercapnic respiratory failure requiring non-invasive ventilation. The record documents that the respiratory failure is the condition that occasioned the admission. Chronic respiratory failure is also documented.
Show coded answer & rationale
| Seq | Code | Description |
|---|---|---|
| 1 | J96.22 | Acute and chronic respiratory failure with hypercapnia — verify the exact code in the Tabular List; principal diagnosis |
| 2 | J44.1 | Chronic obstructive pulmonary disease with (acute) exacerbation, if documented |
Rationale. Guideline I.C.10.b.1 states that a code from subcategory J96.0 or J96.2 may be assigned as a principal diagnosis when it is the condition established after study to be chiefly responsible for occasioning the admission and the selection is supported by the Alphabetic Index and Tabular List, subject to chapter-specific sequencing guidelines taking precedence. Read the Tabular List notes at J96 and J44 before finalising, because the instructional notes govern over the guideline under Section I.A.
Guideline: Section I.C.10.b.1, Section I.A
A patient is admitted with pneumonia due to Streptococcus pneumoniae, is intubated on day two, and on day six the provider documents ventilator associated pneumonia due to Pseudomonas aeruginosa.
Show coded answer & rationale
| Seq | Code | Description |
|---|---|---|
| 1 | J13 | Pneumonia due to Streptococcus pneumoniae — principal diagnosis, the pneumonia diagnosed at the time of admission |
| 2 | J95.851 | Ventilator associated pneumonia — additional diagnosis |
| 3 | B96.5 | Pseudomonas as the cause of diseases classified elsewhere |
| 4 | Z99.11 | Dependence on respirator [ventilator] status, if applicable |
Rationale. Guideline I.C.10.d.2 addresses this exact pattern: a patient may be admitted with one type of pneumonia, for example J13, and subsequently develop VAP, in which case the principal diagnosis is the appropriate code from J12-J18 for the pneumonia diagnosed at admission and J95.851 is assigned as an additional diagnosis where the provider has documented VAP. Guideline I.C.10.d.1 requires the organism code and prohibits an additional J12-J18 code for the VAP itself. The POA indicator for J95.851 would be N.
Guideline: Section I.C.10.d.1, I.C.10.d.2; Appendix I
A young adult presents with lung injury attributed by the provider to vaping, with shortness of breath, cough, and also nausea, vomiting and abdominal pain. Acute respiratory failure develops and is documented.
Show coded answer & rationale
| Seq | Code | Description |
|---|---|---|
| 1 | U07.0 | Vaping-related disorder — principal diagnosis |
| 2 | J96.0- | Acute respiratory failure, the applicable code |
| 3 | R11.2 | Nausea with vomiting |
| 4 | R10.9 | Unspecified abdominal pain, or the specific site documented |
Rationale. Guideline I.C.10.e directs U07.0 as the principal diagnosis for conditions related to vaping, with only U07.0 for the lung injury itself and additional codes for other manifestations such as acute respiratory failure. The guideline then draws a precise line on symptoms: associated respiratory signs and symptoms such as cough and shortness of breath are not coded separately once a definitive diagnosis is established, but it is appropriate to code separately any gastrointestinal symptoms such as diarrhoea and abdominal pain. This is a chapter-specific application of the general rule at Section I.B.5 and I.B.6.
Guideline: Section I.C.10.e; Section I.B.5, I.B.6
Primary sources#
- ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027CMS — the source document for every page on this site (effective 1 Oct 2026)
- NCHS ICD-10-CM files — Tabular List, Index, POA exempt listOfficial code files, addenda and the list of codes exempt from POA reporting
- ICD-10 Coordination and Maintenance CommitteeWhere code proposals are debated; agendas, summaries and meeting materials
- CMS ICD-10 homeCode sets, transition guidance and Medicare coding policy
- AHA Coding ClinicOfficial coding advice from the AHA Central Office — subscription required
- HHS OIG Work PlanActive audit topics — useful for prioritising internal coding audits
- MEDESUN Medical Coding AcademyTraining, credential preparation and audit services by the author