RESPIRATORY FAILURE

'Respiratory failure' is a medical term for inadequate gas exchange by the respiratory system. Respiratory failure can be indicated by observing a drop in blood oxygen level (hypoxemia) and/or a rise in arterial carbon dioxide (hypercapnia) which can be written as (PaO2 < 60 mmHg, PaCO2 > 45 mmHg).
Classification into type I or type II relates to the absence or presence of hypercapnia respectively. (Values in kPA being PO2 below 8kPA and PCO2 above 6.7kPa

Contents

Types

Type 1

Type 2

Causes

Treatment

Types

Type 1

★ Type 1 respiratory failure is defined as hypoxia without hypercapnia, indeed the CO₂ level may be normal or low. It is typically caused by a ventilation/perfusion mismatch; the air flowing in and out of the lungs is not matched with the flow of blood to the lungs.

Type 2

★ Type 2 respiratory failure is defined build up of carbon dioxide that has been generated by the body. The underlying causes are reduced breathing effort (in the fatigued patient), increased resistance to breathing (such as in asthma) or an increase in the area of the lung that is not available for gas exchange (such as in emphysema).

Causes

★ Pulmonary dysfunction

★
★ Asthma

★
★ Emphysema

★
★ Chronic obstructive airway disease

★
★ Pneumonia

★
★ Pneumothorax

★
★ Hemothorax

★
★ Acute Respiratory Distress Syndrome ('ARDS') is a specific and life-threatening type of respiratory failure.

★
★ Cystic Fibrosis

★ Cardiac dysfunction

★
★ Pulmonary edema

★
★ Arrhythmia

★
★ Congestive heart failure

★
★ Valve pathology

★ Other

★
★ Fatigue due to prolonged tachypnoea in metabolic acidosis

★
★ Intoxication with drugs (i.e. morphine, benzodiazepines) suppresses respiration.

Treatment

Emergency treatment follows the principles of cardiopulmonary resuscitation. Treatment of the underlying cause is required. Mechanical ventilation may be required.