Lung Physiology 5: respiratory failure Flashcards
what is respiratory failure?
inadequate gas exchange by respiratory system meaning blood gases cannot be maintained at a good level (must have low PaO2, may or may not have rise in PaCO2)
Describe the 2 types of respiratory failure?
Type 1 respiratory failure:
respiratory system cannot adequately provide oxygen to the body, leading to hypoxemia. (Low PaO2, low/normal PaCO2)
Type 2 respiratory failure:
respiratory system cannot sufficiently remove carbon dioxide from the body, leading to hypercapnia.
(Low PaO2, high PaCO2)
hypoxaemia vs hypoxia
Hypoxaemia; a decrease in the partial pressure of oxygen in the blood
Hypoxia; a reduced level of tissue oxygenation
acute or chronic respiratory failure
any lungs can have lung failure
Type 1 respiratory failure mechanism:
causes,
Most pulmonary and cardiac causes produce type I failure
Mismatching of ventilation and perfusion
Shunting
Diffusion impairment
Alveolar hypoventilation
MANY individual causes, including, infection, congenital, neoplasm, airway, vascular, parenchyma (lung tissue)
Type 2 respiratory failure mechanism:
typical causes
Lack of respiratory drive
Excess workload
Bellows failure
MANY individual causes, including airway, drugs, metabolic, neurological, muscle, polyneuropathy, primary muscle disorders
what is cyanosis? clinical symptoms, feature of hypoxic anaemic
a bluish-purple color of the skin- easiest seen under the tongue
if hypoxic anaemic- may not be able to see blue, not enough haemoglobin to see blue tinge
Central Cyanosis
Oral cavity
May not be obvious in anaemic patients
Irritability
Reduced intellectual function
Reduced consciousness
Clinical features of hypercapnia
Irritability
Headache
Papilloedema
Warm skin
Bounding pulse
Leading to:
Confusion
Somnolence
Coma
chronic hypercapnic patients e.g. COPD lose CO2 drive, chemoreceptors are thought to reset, rely on hypoxic drive to breath (aim for SpO2 to 88-92%)
