Causes and consequences of acute and chronic respiratory failure, classification

Introduction

Respiratory failure can be defined as a condition in which tissues have insufficient oxygen or an overload of carbon dioxide. When respiratory failure is sudden this is acute, when it occurs over time this is classified as chronic.

Classification

Respiratory failure can be divided into 2 types:

Type 1: Hypoxemic Respiratory Failure - type 1 occurs when the respiratory system cannot provide adequate oxygen to the body, causing hypoxemia.

- in type 1 the defining characteristic is the PaO2 < 60 mmHg with normal or decreased PaCO2 (Mirabile et al., 2023).

- etiologies: alveolar hypoventilation, low atmospheric pressure, diffusion defect, ventilation/perfusion mismatch

Type 2 Hypercapnic Respiratory Failure - type 2 occurs when the respiratory system fails to properly remove carbon dioxide from the body, causing hypercapnia.

- in type 2 the defining characteristic is an increase in arterial CO2 with PaCO2 > 45 mmHg and a pH < 7.35 (Mirabile et al., 2023).

- etiologies: alveolar hypoventilation, CO2 production increase, respiratory pump failure, increased dead space

These types can be further subdivided into acute and chronic respiratory failure.

Causes

Acute respiratory failure can be caused by:

- Sepsis

- Aspiration of vomit

- Severe pneumonia

- Severe COVID-19

- Pancreatitis

- Head injury that damages respiratory centers

- Injury to the chest that damaged the lungs

Chronic Respiratory Failure can be caused by:

- Stroke

- Cystic fibrosis

- Amyotrophic lateral sclerosis

- Heart failure

- Muscular dystrophy

- Scoliosis

Complications

Complications of acute respiratory failure include:

- pulmonary emboli

- fibrosis

- pneumonia

- barotrauma

- gastrointestinal hemorrhage

- renal failure

- infection

- thrombocytopenia

Complications of chronic respiratory failure include:

- pulmonary vasoconstriction which leads to pulmonary arterial hypertension, straining the right ventricle

- the strain on the right ventricle leads to impaired function and the patient can manifest features of right heart failure like peripheral edema

Sources

Pingleton SK. Complications of acute respiratory failure. Med Clin North Am. 1983;67(3):725-746. doi:10.1016/s0025-7125(16)31200-7

Creagh-Brown, Ben. “Respiratory Failure,” Medicine, vol. 44, no. 6, 2016, pp. 342–345, https://doi.org/10.1016/j.mpmed.2016.03.005 (accessed December 19, 2025).

VA Health. “Respiratory Failure,” UVA Health, https://www.uvahealth.com/conditions/respiratory-failure (accessed December 19, 2025)

Tampa General Hospital. “Acute Respiratory Failure,” Tampa General Hospital, https://www.tgh.org/institutes-and-services/conditions/acute-respiratory-failure (accessed December 19, 2025)

Mirabile VS, Shebl E, Sankari A, et al. Respiratory Failure in Adults. [Updated 2023 Jun 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526127

Cleveland Clinic. “Respiratory Failure,” Cleveland Clinic, https://my.clevelandclinic.org/health/diseases/24835-respiratory-failure (accessed December 19, 2025). Cleveland Clinic