Respiratory failure
From Ask Dr Wiki
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
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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.
This type is caused by conditions that affect oxygenation like:
- Parenchymal disease(v-q mismatch)
- Diseases of vasculature and shunts.
Type 2
Type 2 respiratory failure is defined as the build up of carbon dioxide that has been generated by the body. The underlying causes include:
- Reduced breathing effort (in the fatigued patient)
- Increased resistance to breathing (such as in asthma)
- A decrease in the area of the lung 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.
