- Respiratory failure
Respiratory failure is a medical term for inadequate
gas exchange by therespiratory system . Respiratory failure can be indicated by observing a drop in bloodoxygenation (hypoxemia ) and/or a rise in arterialcarbon 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 6.7 kPaTypes
Type 1
Type 1 respiratory failure is defined as
hypoxaemia withouthypercapnia , 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.Basic defect in type 1 respiratory failure is failure of oxygenation characterized by: PaO2-low(<60mmhg)PaCO2_normal/low(=49mm hg) PA-aO2-increasdThis type is caused by conditions that affect oxygenation like:
* Parenchymal disease(V/Q mismatch)
* Diseases of vasculature and shunts.right to left shunt, ARDS,pneumonia,Emphysema.Type 2
Type 2 respiratory failure is caused by increased airway resistance. both oxygen and carbon di oxide is affected. 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 inasthma )
* A decrease in the area of the lung available for gas exchange (such as inemphysema ).basically there is defect in ventillation, characterised by: Pao2-decreased PaCO2-increased, PA-aO2-normalCauses
*Pulmonary dysfunction
**Asthma
**Emphysema
**Chronic Obstructive Pulmonary Disease
**Pneumonia
**Pneumothorax
**Pulmonary contusion cite journal |author=Johnson SB |title=Tracheobronchial injury |journal= Seminars in Thoracic and Cardiovascular Surgery |volume=20 |issue=1 |pages=52–57 |year= 2008 |pmid=18420127 |doi=10.1053/j.semtcvs.2007.09.001]
**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 inmetabolic acidosis
**Intoxication with drugs (e.g.morphine ,benzodiazepine s) that suppress respiration.Treatment
Emergency treatment follows the principles of
cardiopulmonary resuscitation . Treatment of the underlying cause is required.Endotracheal intubation andmechanical ventilation may be required.Respiratory stimulant s such asdoxapram may be used, and if the respiratory failure resulted from anoverdose ofsedative drugs such asopioid s orbenzodiazepines , then the appropriateantidote such asnaloxone orflumazenil will be given.ee also
*
Ventilation/perfusion ratio
*Pulmonary shunt References
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