RESPIRATORY FAILURE

✓ Medically ReviewedDISEASEID: MDBT0063🚨 TRIAGE: EMERGENCYICD-10: J96.9

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Definition

CLINICAL DEFINITION

Respiratory failure is failure to keep normal gas exchange (oxygen uptake and carbon dioxide removal). It is marked by low artery oxygen (hypoxaemia, low blood oxygen) on blood gas (artery blood test). Type 1 is low oxygen with normal or low carbon dioxide. Type 2 is low oxygen with high carbon dioxide (hypercapnia, high blood gas) from poor pumping. Forms are acute (sudden), chronic (lasting) and acute on chronic (sudden worsening).

IN PLAIN ENGLISH

The lungs fail to put enough oxygen in the blood. They may also fail to clear out carbon dioxide gas. This causes gasping, confusion, sleepiness or blue lips. A blood test from an artery confirms it. Urgent oxygen and cause treatment are needed.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Respiratory failure is not plain breathlessness (dyspnoea, short breath feeling) with normal gases. It is not low oxygen carriage from anaemia (low red protein) when artery pressure is normal. It is not over-breathing from anxiety with high oxygen and low carbon dioxide. It is not full breathing arrest (complete stop), which is the end stage if failure is untreated.

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Word Breakdown

re-

=again or back, forming respiration

spir-

=to breathe

-ory

=relating to, plus failure as loss of function

Literal Meaning: breathing function that has failed

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Abbreviations

ARF=Acute respiratory failure - sudden loss of gas exchange

CRF=Chronic respiratory failure - lasting loss of gas exchange

ABG=Arterial blood gas - artery blood test for oxygen and carbon dioxide

PaO2=Arterial oxygen pressure - oxygen level in artery blood

PaCO2=Arterial carbon dioxide pressure - carbon dioxide level in artery blood

NIV=Non-invasive ventilation - mask breathing support without windpipe tube

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Synonyms & Variants

Respiratory insufficiency›Ventilatory failure›Respiratory decompensation›

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Category-Specific Context

Respiratory failure is a Disease because it is decompensated (body not coping) failure with set gas thresholds and organ harm. It follows lung, chest, nerve, muscle and brain causes. Care pairs cause treatment with oxygen and breathing support. Delay risks arrest and multiorgan injury (many organ harm).

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Clinical Context & Usage

CLINICAL SETTINGS

Emergency DepartmentIntensive Care UnitRespiratory and Acute Medical WardsPostoperative Recovery UnitPrehospital and Ambulance Care

USAGE & DOCUMENTATION NOTES

Use the term with type, timing and gas values. State Type 1 (low oxygen) versus Type 2 (low oxygen plus high carbon dioxide). State acute (sudden), chronic (lasting) or acute on chronic (sudden worsening). Link each case to cause, acidity (blood acid level), alertness and support need.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Exchange needs air reaching sacs, blood reaching sacs and oxygen crossing the membrane. Mismatch (uneven air and blood) is the top cause of low oxygen. Shunt (blood passing without oxygen pickup) follows filled or collapsed sacs. Low pumping raises carbon dioxide and lowers oxygen together. Stiff lungs, fluid, clots and weak muscles each break a different link.

PRIMARY CAUSES

COPD exacerbation (chronic airflow blockage flare)

Narrowed tubes plus trapped air cause mismatch (uneven air and blood) with low oxygen. Poor pumping later raises carbon dioxide.

Asthma exacerbation (sudden asthma flare)

Tight airways plus mucus plugs raise resistance and trap air. Work of breathing (breathing effort) soars with low oxygen then high carbon dioxide from fatigue.

Pneumonia (lung infection)

Pus filled sacs create shunt (blood without oxygen pickup) with low oxygen resisting extra oxygen. Severe disease cuts pumping with rising carbon dioxide.

Acute respiratory distress syndrome or ARDS (sudden widespread lung injury)

Diffuse sac injury plus stiff lungs (hard to expand) create shunt with severe low oxygen. Dead space (air without blood) can raise carbon dioxide.

Cardiogenic pulmonary oedema (lung fluid from heart failure)

High left heart pressure floods tissue and sacs. Oxygen transfer fails with mismatch that eases after fluid removal and pressure control.

Pulmonary embolism (lung vessel clot)

Blocked arteries create dead space (air without blood) with low oxygen and fast breathing. Large clots cause shock (circulation collapse).

Pneumothorax (collapsed lung from air around lung)

Collapsed zones cut ventilated area causing shunt and mismatch with low oxygen. Tension (pressure buildup) blocks vein return (blood to heart) and pumping.

Neuromuscular and brain drive disorders including Guillain-Barre syndrome and myasthenia gravis

Weak pump from nerve or muscle failure or low brain drive causes low air movement. High carbon dioxide with low oxygen follows with weak cough.

Chest wall restriction and obesity hypoventilation (curved spine, obesity, weak diaphragm)

Small breaths with base collapse (lung flattening) cause low pumping. Both low oxygen and high carbon dioxide persist, worse in sleep.

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Drug-Induced Causes

💊 Opioids including morphine, fentanyl and codeine ↗

Mechanism: Damp brain breathing centre and blunt carbon dioxide response, causing slow shallow breaths with high carbon dioxide and low oxygen

→ Lower or stop dose, watch with oxygen and carbon dioxide monitors, consider naloxone (opioid antidote) for severe slowing, support airway and breathing

💊 Benzodiazepines and sedatives including diazepam, midazolam and propofol ↗

Mechanism: Cut central drive and throat tone, worsening low pumping, mainly with opioids or in COPD (chronic lung disease)

→ Stop culprit, avoid combined sedation, track gases and alertness, support breathing in monitored care

💊 Neuromuscular blockers and myasthenia worsening agents including rocuronium and gentamicin ↗

Mechanism: Block nerve to muscle signals causing weakness and poor pump function with retained carbon dioxide

→ Stop drug, test strength and gases urgently, give reversal where fitting, provide breathing support

💊 Amiodarone, nitrofurantoin and bleomycin lung toxicity ↗

Mechanism: Cause tissue injury and scarring or immune reaction impairing oxygen transfer with low oxygen

→ Stop drug, give oxygen to target, seek specialist advice on steroids (inflammation drugs) and imaging, track gases and lung function

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Epidemiology

Prevalence:Respiratory failure is common in emergency and intensive care worldwide. It complicates COPD (chronic lung disease), pneumonia (lung infection), heart failure, sepsis (severe infection response) and trauma. Risk rises with age, smoking, air pollution and frailty (low reserve). Rates vary by cause and setting.

Age Group:All ages can be affected across causes. Risk is highest in older adults with chronic lung or heart disease. Early-born babies and young children with small airway infection are vulnerable. Young adults are hit mainly by asthma, trauma, overdose and collapsed lung.

Geographic Distribution:Respiratory failure occurs worldwide in all health systems. Burden tracks smoking, indoor fuel smoke, air pollution and tuberculosis (lung germ infection) patterns. Outcomes track access to oxygen monitoring, mask ventilation and intensive care.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 EMERGENCY

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Tension pneumothorax (pressure buildup collapsing lung and flow)
Massive embolism (large clot blocking lung vessels)
Severe allergy closing the airway
Opioid or sedative overdose with low pumping
Guillain-Barre or myasthenic crisis (nerve muscle weakness)
Sudden lung fluid from heart failure

URGENT EVALUATION TRIGGERS

SpO2 below 90 percent on oxygen or cannot speak full sentences
New drowsiness, confusion, headache or bounding pulse with high carbon dioxide
Blue lips, neck strain, windpipe tug or belly chest moving oppositely
pH below 7.30, rising carbon dioxide, falling oxygen or rising lactate (acid marker)
Chest pain, one-sided leg swelling, treatment-resistant wheeze or fever with new shadow

Contraindications & Precautions

CONTRAINDICATIONS

Do not withhold oxygen while awaiting gases when low oxygen is present
Do not give uncontrolled high flow oxygen without target setting in COPD (chronic lung disease) prone to carbon dioxide rise
Do not use heavy sedation without airway watch in high carbon dioxide cases
Do not use mask ventilation with coma, vomiting with inhale risk, face injury blocking seal or untreated collapsed lung

SPECIAL PRECAUTIONS

Set oxygen to target range and recheck gases early
Track alertness, breathing rate, neck muscle strain and acidity (acid level)
Check for collapsed lung, blocked mucus, tight airways and fluid overload before pressure support
Set escalation, tube thresholds and resuscitation wishes early in severe disease

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Cardiac arrest and malignant rhythm
Brain injury from low oxygen with confusion or coma
Multiorgan failure of kidney, liver and heart
Aspiration with ventilator lung infection
Pressure lung injury with collapsed lung
Muscle weakness with prolonged machine dependence

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Reference Ranges

NORMAL RANGEPaO2 (artery oxygen pressure) 11 to 13 kPa on room air at sea level. PaCO2 (artery carbon dioxide pressure) 4.7 to 6.0 kPa. SpO2 (finger probe oxygen) 94 to 98 percent in most acutely ill adults. Target 88 to 92 percent in COPD (chronic lung disease) prone to carbon dioxide rise.

CRITICAL (PANIC) VALUEPaO2 below 8 kPa on room air marks failure. PaCO2 above 6.5 kPa with low oxygen marks Type 2 (high carbon dioxide) failure. New acidity below pH 7.30, SpO2 below 90 percent with distress, blue lips or new drowsiness signals emergency needing breathing support.

UNIT OF MEASUREMENTkPa for PaO2 and PaCO2 with mmHg in brackets; percent for SpO2 and FiO2 (inhaled oxygen share).

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Respiratory distress

Distress is raised work with symptoms but gases may still cope, while failure is proven gas collapse by thresholds; confused because both cause fast breathing

Respiratory arrest

Arrest is full breathing stop needing instant restart, while failure is weak but present breathing; confused because arrest is the end stage of untreated failure

Respiratory insufficiency

Insufficiency often means mild or coping impairment, while failure is decompensated (not coping) gas abnormality needing support

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Breathlessness without failure

Key Distinguishing Feature: Fast breathing with normal artery gases, while failure needs low oxygen with or without high carbon dioxide

Anxiety over-breathing

Key Distinguishing Feature: High oxygen with low carbon dioxide and alkaline blood, opposite to Type 2 failure with acid blood

Carbon monoxide poisoning

Key Distinguishing Feature: Normal oxygen pressure but low oxygen carriage with high carboxyhaemoglobin (gas bound red protein)

Heart failure with preserved gases

Key Distinguishing Feature: Crackles and swelling but gases normal early, while failure shows threshold breach plus raised work

Neuromuscular weakness before failure

Key Distinguishing Feature: Tiring weakness with low blow test but gases normal at first, while failure adds high carbon dioxide with acidity

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Clinical Pearls

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Split Type 1 low oxygen alone from Type 2 low oxygen plus high carbon dioxide at once. Type 2 points to pump failure or low drive and needs ventilation thinking.

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Recheck gases and alertness after starting oxygen, mainly in COPD. Extra oxygen can mask low pumping while carbon dioxide climbs.

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Set oxygen 88 to 92 percent in COPD prone to carbon dioxide rise and recheck gases early. Uncontrolled oxygen can worsen retention and acidity.

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Treat rising carbon dioxide with slowing breaths and drowsiness as pre-arrest, not improvement. Arrange instant airway and ventilation review.

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Start mask ventilation early for acid Type 2 flare with COPD per protocol. Escalate to tube and intensive care when acidity or alertness worsens.

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Example Usage & SOAP

CLINICAL SENTENCE

""68-year-old with COPD flare turned drowsy overnight with Type 2 failure and raised carbon dioxide.""

IN A SOAP NOTE

S: 68-year-old with more breathlessness and drowsiness overnight, green sputum cough. O: Temp 38.1C, BP 142/88, HR 112, RR 30, SpO2 86 percent on air and 91 percent on 2L, drowsy but rousable, neck muscle strain, wheeze and crackles, gases low oxygen with high carbon dioxide and acid pH. A: Type 2 failure from COPD flare with pneumonia. P: Controlled oxygen to 88 to 92 percent, mist bronchodilators, steroids and antibiotics, repeat gases, mask ventilation review, intensive care alert, alertness and pH watch.

DIFFERENTIAL DIAGNOSIS CONTEXT

Low oxygen with normal carbon dioxide points to shunt (blood without pickup) from pneumonia or lung fluid. Low oxygen with high carbon dioxide points to low pumping from COPD or muscle weakness. High oxygen with low carbon dioxide points to over-breathing, not failure.

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Classifications & Scoring

GRADING SYSTEM

Berlin Definition of ARDS

Grades widespread lung injury by oxygen pressure to inhaled oxygen ratio with pressure support into mild, moderate and severe bands

SCORING TOOL

SOFA Score

Tracks organ failure across lungs, circulation, liver, kidney, brain and clotting to follow critical illness

SCORING TOOL

APACHE II Score

Estimates intensive care death risk from physiology, age and chronic health on admission

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Prognosis

SHORT-TERM OUTCOME

Short term risk spans fast recovery to death by cause and gas severity. Type 1 from pneumonia or lung fluid often lifts quickly with cause care. Type 2 with acid blood and coma needs intensive support and carries higher instant risk. Acidity (acid level), alertness and oxygen response guide path.

LONG-TERM PROGNOSIS

Long term course follows base disease and frailty (low reserve). Many with COPD (chronic lung disease) or scarring develop repeat failure needing home oxygen or night mask support. Rehab, stopping smoking, vaccines and advance planning cut readmission. Severe ARDS (widespread injury) survivors may carry lasting lung, muscle and thinking effects.

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References & Coding

ICD-10 DIAGNOSTIC CODE

J96.9

LITERATURE CITATIONS & GUIDELINES

[1]British Thoracic Society emergency oxygen guidance

[2]NICE NG115 Chronic obstructive pulmonary disease diagnosis and management

[3]Berlin Definition of ARDS JAMA 2012

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.