What is a respiratory failure?
When the pulmonary gas exchange fails to keep normal arterial oxygen and carbon dioxide level respiratory failure results.
-Respiratory failure can be defined in two ways.
Type 1-Failure of oxygenation resulting in PaO2 lesser than 8. 0 KPa
Type 2 -Failure of ventilation resulting in PaCO2 greater than 7.7 KPa with accompanying acid base changes.
The basis of classification is the absence or presence of hypercapnia.
CAUSES OF RESPIRATORY FAILURE
1. Airway obstruction:
Upper airway- obstructive sleep apnoea, trauma, angio oedema, foreign body inhaling
Lower airway- Chronic Obstructive Pulmonary Disease (COPD), asthma, cystic fibrosis
2. Disorders of lung parenchyma:
Acute
Acute respiratory distress syndrome.
It includes the following conditions
A-Pneumonia.
B-Acute pulmonary edema
C-Acute pulmonary embolism.
Chronic
It may be due to-
a-Chronic fibrosing alveolitis
b-Pneumoconiosis
c-Sarcoidosis
3. Disorders of the respiratory muscle pump
Neurological
Examples are -Brain stem disease, over sedation, central sleep apnoea, and cervical cord trauma.
Musculoskeletal
Examples are scoliosis, chest wall trauma, muscular dystrophy.
Clinical features
X Due to hypoxemia:
Patient becomes restless, mental confusion, sweating, tachycardia, and central cyanosis, depressed level of consciousness, poor peripheral circulation, and cardiac arrhythmias.
X Due to hypercapnia:
Breathlessness, headache, warm extremities, bounding pulse, muscle twitching, elevated blood pressure, papilledema occasionally, cardiac dysrhythmias.
Effects on CNS functions -such as asterixis, hyperreflexia, miosis, confusion and coma.
