ICD-11 Chapter 12: Diseases of the respiratory system

What is Chapter 12 of ICD-11?

The Chapter 12 group the respiratory system diseases. In the ICD-10 it corresponded to Chapter X (J00–J99). ICD-11 restructures it to reflect current clinical terminology and advances in pulmonology.

The chapter has two main hierarchies:

By type of disease/disorder: broad category → specific disease with anatomy included → greater specificity
By anatomy: anatomical category → specific disease → greater specificity

Fundamental changes vs ICD-10:

The flu moved to Chapter 01 (infectious diseases): 1E30–1E32
The breathing-related sleep disorders (sleep apnea) moved to Chapter 07 (sleep disorders)
The cystic fibrosis was incorporated into Chapter 12 (formerly in metabolic) as part of "Certain diseases of the lower respiratory tract"
New section: Inhalation, occupational and environmental lung diseases
Disorders of the mediastinum and diaphragm were moved to the pleural disorders
The neoplasms of the respiratory system They are in Chapter 02, not here
The developmental respiratory diseases They are in Chapter 20

Chapter 12 Blocks

CA00–CA0Z

Upper respiratory tract disorders

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It includes non-infectious diseases of the upper respiratory tract, plus infections that remain in Chapter 12 (infectious diseases due to a specific agent are in Chapter 01). This section combines what was in ICD-10 in J00–J06 and J30–J39.

Code	Diagnosis
CA00	Acute nasopharyngitis
CA01	Acute sinusitis
CA03	Acute tonsillitis
CA04	Acute laryngopharyngitis
CA07	Acute upper respiratory infections of multiple and unspecified sites
CA08	Vasomotor or allergic rhinitis
CA0D	Deviated nasal septum
CA0F	Chronic diseases of tonsils or adenoids
CA0J	Nasal polyp

Mortality rule — CA00 Acute nasopharyngitis: If mentioned with immobility (MB44.3), code to CA40.Z Pneumonia, unspecified organism. Acute nasopharyngitis is not accepted as a cause of infectious meningitis: code to meningitis.

CA40–CA4Z

Lung infections

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ICD-11 groups in this block what was in ICD-10 in J12–J22: influenza with pneumonia, other pneumonias, bronchiolitis and acute bronchitis. Influenza without pneumonia moved to Chapter 01 (1E30–1E32). Pulmonary infections due to a known specific agent are also in Chapter 01.

Code	Diagnosis
CA40	Pneumonia
CA40.0	Bacterial pneumonia
CA40.1	Viral pneumonia
CA40.07	Pneumonia due to Streptococcus pneumoniae
CA40.Z	Pneumonia, organism unspecified
CA41	Acute bronchiolitis
CA42	Acute bronchitis
CA27	Tracheobronchitis

Rule CA07 → lung infections: Acute upper respiratory infections (CA07) are accepted as a cause of bronchitis (CA20), COPD (CA22), tracheobronchitis (CA27), pneumonia (CA40), bronchiolitis (CA41) and acute bronchitis (CA42). Code to the most specific condition when mentioned.

CA20–CA2Z

Certain diseases of the lower respiratory tract

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Includes chronic obstructive diseases and other diseases of the lower respiratory tract. COPD became a separate category. Cystic fibrosis was incorporated here from the old metabolic chapter. It mainly corresponds to J40–J47 of the ICD-10.

Code	Diagnosis
CA20	Bronchitis
CA20.1	Chronic bronchitis
CA21	Emphysema
CA22	Chronic obstructive pulmonary disease
CA22.0	Chronic obstructive pulmonary disease with acute exacerbation, unspecified
CA22.1	Certain specified chronic obstructive pulmonary disease
CA22.Z	Chronic obstructive pulmonary disease, unspecified
CA23	Asthma
CA24	Bronchiectasis
CA25	Cystic fibrosis

Mortality rules — COPD and bronchitis:

CA42 (acute bronchitis) + CA20.1 (chronic bronchitis) → code CA20.1
CA42 (acute bronchitis) + CA22 (COPD) → code CA22
CA20 (bronchitis) + CA21 (emphysema) → code CA22 COPD
CA20 (bronchitis) + CA23 (asthma) → code CA22 COPD
CA22.Z (COPD) + CA40 (pneumonia) → code CA22.1 (COPD with acute infection)

CA60–CA6Z

Inhalation, occupational and environmental lung diseases

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New section in ICD-11, based on input from the WHO Division of Occupational Health. Improves the classification of respiratory disorders according to their etiology. In ICD-10 it corresponded to J60–J70.

Code	Diagnosis
CA60	Pneumoconiosis
CA60.0	Pneumoconiosis due to dust containing silica
CA60.2	Pneumoconiosis due to mineral fibres including asbestos
CA60.1	Coal worker pneumoconiosis
CA60.3	Pneumoconiosis associated with tuberculosis
CA8Y	Other specified lung diseases due to external agents

CA60 Pneumoconiosis + tuberculosis: When tuberculosis of the respiratory system (1B10) is mentioned together with pneumoconiosis (CA60), code to CA60.3 Pneumoconiosis associated with tuberculosis.

CB03.4–CB4Z

Respiratory diseases that mainly affect the pulmonary interstitium

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ICD-11 creates the idiopathic interstitial pneumonitis as an independent category. A new category is added for Specific primary interstitial lung diseases of infancy and childhood. In ICD-10 it was J80–J84.

Code	Diagnosis
CB03.4	Idiopathic pulmonary fibrosis
CB03.4	Idiopathic pulmonary fibrosis
CB41	Respiratory failure
CB41.0	Acute respiratory failure
CB41.2	Respiratory failure, unspecified as acute or chronic
CB41.2Z	Respiratory failure, unspecified
4B20.Z	Sarcoidosis, unspecified

Respiratory failure — ill-defined condition: According to the WHO Reference Guide, both CB41.0 (acute respiratory failure) such as CB41.2 (unspecified respiratory failure) are conditions poorly defined and should not be used as the underlying cause of death. The underlying causes must be identified.

CB27–CB2Z

Pleural, diaphragm, and mediastinal disorders

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Disorders of the mediastinum and diaphragm were moved to this section in ICD-11. In ICD-10, pleural disorders were in J90–J94 and mediastinal disorders in J98.5. They now form a unified block.

Code	Diagnosis
CB27	Pleural effusion
CB21	Pneumothorax
CB21.Z	Pneumothorax, unspecified
MD31	Pleurisy
CB21.0	Spontaneous tension pneumothorax
CB23	Disorders of diaphragm
CB22	Diseases of mediastinum, not elsewhere classified

CB01 BB00.0–CB1Z

Pulmonary edema, pulmonary thromboembolism and other respiratory diseases

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Includes pulmonary edema and pulmonary thromboembolism. Pulmonary embolism is in Chapter 11 (BB00), while pulmonary edema of cardiac origin is associated with left ventricular failure.

Code	Diagnosis
CB01	Pulmonary oedema
BB00.0	Acute pulmonary thromboembolism

Rule CB01 — Pulmonary edema: When the underlying cause of death is CB01 Pulmonary edema and it is mentioned BD1Z Heart failure unspecified, encode in BD11.Z Left ventricular failure, unspecified.

Ch. 07 — Reference

Sleep disorders related to breathing — Now in Chapter 07

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In ICD-11, sleep disorders related to breathing and respiratory control were moved to Chapter 07 (sleep-wake disorders). They are included secondarily in Chapter 12. On ICD-10, sleep apnea was in G47.3 (neurology).

ICD-11 code	Diagnosis	Before ICD-10
7A41	Obstructive sleep apnoea	G47.33
7A40	Central sleep apnoeas	G47.31
7A4Z	Sleep-related breathing disorders, unspecified	G47.3x

CB60–CB64

Respiratory system disorders after a procedure

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Expanded section in ICD-11 with respect to J95 of ICD-10. Includes post-surgical and post-procedural respiratory complications, including pneumothorax due to mechanical ventilation. These codes should not be used as the underlying cause of death.

Code	Diagnosis
CB60	Tracheostomy malfunction
CB64	Transfusion related acute lung injury

Post-coordination example: A right-sided pneumothorax caused by mechanical ventilation is coded: CB21.Z (Pneumothorax, unspecified) + laterality extension code + post-procedure extension code.

Influenza — Moved to Chapter 01

This is the most relevant change for clinicians accustomed to ICD-10. The flu It's no longer in Chapter 12. of ICD-11. The WHO moved it to Chapter 01 because it affects multiple body systems and is a major global public health concern.

ICD-11 code	Diagnosis	Before in ICD-10
1E30	Influenza due to identified seasonal influenza virus	J10
1E31	Influenza due to identified zoonotic or pandemic influenza virus	J09
1E32	Influenza, virus not identified	J11

Comparison ICD-10 vs ICD-11 — Chapter 12

ICD-10 block	ICD-11 Equivalent
J00–J06 Acute upper respiratory tract infections	CA00–CA0Z Upper respiratory tract disorders (specific agent infections → Chap. 01)
J09–J11 Influenza (flu)	1F40–1F4Z — Moved to Chapter 01 (infectious diseases)
J12–J18 Pneumonia	CA40–CA4Z Lung infections (includes pneumonia, bronchiolitis, acute bronchitis)
J20–J22 Other acute lower tract infections	Combined in CA40–CA4Z Lung infections
J30–J39 Other upper respiratory diseases	Combined in CA00–CA0Z Upper respiratory tract disorders
J40–J47 Chronic lower respiratory tract diseases	CA20–CA2Z Certain diseases of the lower respiratory tract (COPD category independent; cystic fibrosis incorporated)
J60–J70 Lung diseases due to external agents	CA60–CA6Z New section: Inhalation, occupational and environmental lung diseases
J80–J84 Other respiratory diseases affecting the interstitium	CB40–CB4Z Interstitial respiratory diseases (idiopathic pneumonitis as an independent category)
J85–J86 Suppurative and necrotic conditions	Combined in CA40–CA4Z Lung infections
J90–J94 Other diseases of the pleura	CB20–CB2Z Pleural, diaphragm, and mediastinal disorders
J95–J99 Other diseases of the respiratory system	CB60–CB64 Postprocedure disorders (expanded) · Mediastinum/diaphragm disorders → CB20–CB2Z
G47.3x Sleep apnea (neurology)	7A40–7A42 Moved to Chapter 07 (sleep disorders)
E84 Cystic fibrosis (metabolic)	CA25 Cystic fibrosis — added to Chapter 12 (lower respiratory tract)

Frequently asked questions

What is the ICD-11 code for COPD?

Chronic obstructive pulmonary disease is CA22. More specific codes and extensions depend on the documented presentation. Use the official coding tool to distinguish exacerbations, associated infections and other details.

What is the ICD-11 code for asthma?

Asthma is CA23 in ICD-11. In ICD-10 it was J45. ICD-11 states that if bronchitis is mentioned along with asthma as a cause of death, it is coded as CA22 COPD.

What is the ICD-11 code for pneumonia?

Pneumonia is CA40. CA40.Z is pneumonia with the organism unspecified, and CA40.07 is pneumonia due to Streptococcus pneumoniae. Other causes have their own subcategories.

Where is influenza in ICD-11?

Influenza moved to Chapter 01 (infectious diseases) in ICD-11. Seasonal influenza is 1E30, pandemic or zoonotic is 1E31, and that of unidentified viruses is 1E32. In ICD-10 it was in J09–J11 of the respiratory chapter.

Where is sleep apnea on ICD-11?

Breathing-related sleep disorders, including sleep apnea, moved to the Chapter 07 (sleep-wake disorders) in the ICD-11. Obstructive sleep apnea is 7A41 and central sleep apnoea is 7A40. On the ICD-10 it was in G47.3 (neurology).

What ICD-11 code does cystic fibrosis have?

Cystic fibrosis is CA25 in ICD-11, within the block of certain diseases of the lower respiratory tract. In ICD-10 it was E84 (metabolic diseases chapter). The ICD-11 moved it to the respiratory chapter because the main cause of death is respiratory involvement.

What is the ICD-11 code for pneumothorax?

Pneumothorax is CB21 in ICD-11. Without specification it is CB21.Z. In ICD-10 it was J93. To specify laterality (right/left), the extension codes from Chapter X are used in postcoordination.

Is respiratory failure a valid underlying cause of death in ICD-11?

No. According to the WHO Reference Guide, both CB41.0 (acute respiratory failure) such as CB41.2 (unspecified respiratory failure) are on the list of ill-defined conditions and should not be used as the underlying cause of death. The underlying causative condition should always be identified.

ℹ️ Source: ICD-11 Reference Guide, February 2023, WHO. Independent information portal. For official clinical coding consult icd.who.int.