Chronic Respiratory Failure

Insuffisance respiratoire chronique

Chronic respiratory failure is defined by the inability of the lungs normally ensure oxygenation of the arterial blood. The result is an arterial hypoxia. The finding of a PaO 2 ≤ 60 mmHg sign a basic IRC.


1- COPD:

– Basic hypoxemia (by shunting)

– Hypercapnia (by alveolar hypoventilation present in advanced disease)

– PH maintained normal renal adaptation (respiratory acidosis compensated): increased tubular reabsorption of bicarbonates (chronic hypercapnia).

– Increasing labor respiratory muscles

– Desensitization of bulbar respiratory centers to hypercapnia stimulus

– Hypoxia becomes the main stimulus

– Hypoxic pulmonary vasoconstriction with PAH more or less fixed, precapillary (elevation precapillary pulmonary pressures without increasing the occlusion pressure)

– Polycythemia secondary to hypoxia


– Infringement of the interstitium: abnormal diffusion with hypoxemia effort initially and basic hypoxemia (advanced disease)

– Infringement of the chest wall: especially alveolar hypoventilation

B- etiologies of IRC:

1- obstructive IRC:

These obstructive pulmonary obstructive chronic bronchitis; Asthma continuous dyspnea; emphysema;
Aside: bronchiectasis (DDB) and cystic fibrosis

2- restrictive IRC:

– Infiltrative diseases of the lung (chronic interstitial disease: pulmonary fibrosis …)

– Violations of the chest: chest deformities; pleural disease; neuromuscular disease.

3- IRC pulmonary vascular disease:

– Chronic pulmonary heart (CPC) post embolic

– Primary pulmonary hypertension.


1- Indications:

– PaO2 ≤ 55 mmHg at baseline (verified at least 2 months away from acute decompensation)

– PaO2 ≤ 60 mmHg if there are signs of right heart failure, polycythemia, nocturnal desaturation.

– Essential Fact: chronic no-shows hypercapnia against the long-term oxygen therapy.

2- ways:

– This is a priori lifelong treatment

– The duration must always be at least 15 hours a day

– The O2 flow must be adapted to obtain a PaO2 ≥ 70 mmHg without increase PaCO2 (one starts with a flow rate of 1L / min)

Developing chronic respiratory failure
Developing chronic respiratory failure


– In case of aggravation of the burden on the respiratory muscles, decompensation means: the exhaustion of the diaphragm, the use of inspiratory accessory muscles (SCM external intercostals); active expiration with the contraction of the abdominals.

– Consequence on gas exchange

* The dramatically worsening alveolar hypoventilation

* Hypercapnia is most aggravated compared to baseline

* Hypoxaemia also worsened relative to baseline

* Respiratory acidosis is decompensated with a decreased pH (kidney adaptation possibilities are exceeded) despite bicarbonates ++.

– Hemodynamic failure by increasing PAH (IVD); the importance of hypoxia may be responsible for neuropsychiatric signs.

– Sweats associated with hypercapnia

– HTA or rarely collapse; it does not (generally) shock sign.

– Disorders of consciousness: drowsiness, coma or agitation and asterixis -> intubation and mechanical ventilation in emergency.

– It is the clinical tolerance that determines the therapeutic approach in emergency

– Mechanical ventilation is the best treatment for the rest of the respiratory muscles, a proper oxygenation with hemodynamic improvement, frequent bronchial aspirations, freeing the airway.

– Non-invasive ventilation by face mask avoiding endotracheal intubation for mechanical ventilation in the absence of impaired consciousness and exhaustion.

– Low-flow nasal O2 (0.5 to 1 L / min) to avoid worsening hypercapnia (risk of oxygen at high flow rate) in chronic hypercapnia.

Indications of mechanical ventilation:

* Respiratory Exhaustion (weak chest expansion, paradoxical breathing, ineffective cough)

* Impaired consciousness, asterixis

* Hypotension or shock

* Respiratory acidosis not quickly improved medical treatment (pH <7.30 persistent)