respiartory conditions Flashcards
what is respiratory failure?
respiratory system fails in one or both of its gas exchange functions (oxygenation and carbon dioxide elimination) due to dysfunction of one or more essential components of the respiratory system:
Chest wall (including pleura and diaphragm)
Airways
Alveolar – capillary units (respiratory membrane)
Pulmonary circulation
CNS (brain stem) & Nerves
what is causes type 1 respiratory failure?
Type 1 is the most common type of respiratory failure and associated with acute diseases of the lung e.g. cardiogenic or non-cardiogenic pulmonary oedema, pneumonia
what causes type 2 respiratory failure?
drug over dose, neuromuscular diseases, chest wall abnormality, severe airway disorders i.e. Asthma or COPD
how long does acute hypercapni respiratory failure develop?
over minutes to hours; therefore, pH is less than 7.3.
how long does it take for chronic respiratory failure to develop?
Chronic respiratory failure develops over several days or longer, allowing time for renal compensation and increase in bicarbonate ion concentration. Therefore, the pH usually is slightly decreased.
what is type 1 respiratory failure?
hypoxaemic. failure of oxygen exchange.
what is type 2 respiratory failure?
hypercapnic respiratory failure.
what is the managment of respiratory failure?
Oxygen supplement
Control of mucus secretions (physiotherapy)
Treatment of lung infection (antibiotics)
Control of airways obstruction (e.g. using bronchodilators, corticosteroids)
Treatment for pulmonary oedema (diuretics)
Reducing load on respiratory muscles
what are some pathophysiological events in respiratory failure?
- Ventilation/Perfusion (V/Q) mismatch
- Shunting (Severe V/Q mismatch)
- Diffusion limitation (i.e. alveolar membrane is thickened/destroyed)
- Alveolar hypoventilation (decreased minute ventilation relative to demand due to airway failure)
what does perfusion mean?
the flow of blood through the tissues.
what pathology affecting ventilation can cause a missmatch between ventilation and perfusion?
copd as less air gets into the alveoli.
what pathology affecting perfussion can cause a missmatch between ventilation and perfusion?
heart failure.
what is a shunt?
Under-ventilated areas of the lungs can cause a shunt where venous blood returns to the heart without collecting its normal oxygen quota
what are causes of a shunt?
Pneumonia
Atelectasis
Severe pulmonary oedema
Hypoxemia caused by a shunt is more difficult to correct by supplementary oxygen administration
when does shunting occur?
Shunting occurs when an illness allows blood to flow through the lungs without picking up enough O2.
Atelectasis- collapsed alveoli
what is the different between a normal lung and a shunt in the lung?
in a normal lung oxygenated blood emerges from the pulmonary capillaries.
in a shunt- deoxygenated blood emerges from some pulmonary cappilaries.
what is cardiogenic pulmonary oedmea
an accumulation of extra fluid in your lungs that can be life-threatening
what cause cardiogenic pulmonary oedema?
Left Ventricular Failure (LVF) – usually as a consequence of MI but can also be consequences of:
Diseases of heart valves
Failures in conduction system of the heart
A reduction in stroke volume (SV) triggers compensatory mechanisms
what is left ventricular heart failure?
occurs when there is dysfunction of the left ventricle causing insufficient delivery of blood to vital body organs.
Poor pumping by damaged left ventricle causes blood to back-up pulmonary veins into lungs
what are symptoms of pulmonary oedema?
Difficulty breathing
Anxiety
Pale skin
Pink frothy sputum
Hypoxia
Orthopnoea (inability to lie down flat due to breathlessness)
Oedema of ankles in later stage
what is acute respiratory distress syndrome?
ARDS is a form of non-cardiogenic pulmonary oedema that can quickly lead to acute respiratory failure .
Fluid accumulates in the lungs interstitium, alveolar space, and small airways, causing the lungs to stiffen
This impairs ventilation and reduces oxygenation of blood.
what other conditions is acute respiratory distress syndrome caused by?
direct injury such as:
Pneumonia
Aspiration of gastric secretion
Drowning
Pulmonary embolism
Trauma (severe chest injury)
Inhalation injury (e.g. smoke inhalation)
indirect injury such as:
Sepsis
Massive blood transfusion reaction
Acute pancreatitis
Severe burns
what is the exudative phase in ARDS?
Exudative phase (first 24 hrs) with hypoxaemia. Leakage of fluid into the alveoli plus haemorrhage and infiltration of neutrophils
what is the second phase in ARDS?
Proliferative phase (14 days after the injury) Persistent hypoxaemia, and reduced lung compliance (decreased surfactant). Thrombi form in the small blood vessels of the lungs