Respiratory failure
Classification and external resources
ICD-10	J96.
ICD-9	518.81
DiseasesDB	6623
eMedicine	med/2011
MeSH	D012131

The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial carbon dioxide levels is called hypercapnia. The normal reference values are: oxygen PaO₂ > 60 mmHg, and carbon dioxide PaCO2 < 45 mmHg (values in kPa being PO₂ below 8kPA and PCO₂ above 6.7 kPa). Classification into type I or type II relates to the absence or presence of hypercapnia respectively.

Contents 1 Types 1.1 Type 1 1.2 Type 2 2 Causes 3 Treatment 4 See also 5 References

[edit] Types

[edit] Type 1

Type 1 respiratory failure is defined as hypoxaemia without hypercapnia, and indeed the P_aCO₂ may be normal or low. It is typically caused by a ventilation/perfusion (V/Q) mismatch; the volume of air flowing in and out of the lungs is not matched with the flow of blood to the lungs. The basic defect in type 1 respiratory failure is failure of oxygenation characterized by:

PaO2	low (< 60mmHg)
PaCO2	normal or low (≤ 49mmHg)
PA-aO2	increased

This type of respiratory failure is caused by conditions that affect oxygenation such as:

• Parenchymal disease (V/Q mismatch)
• Diseases of vasculature and shunts: right-to-left shunt, pulmonary embolism
• interstitial lung diseases: ARDS, pneumonia, emphysema.

[edit] Type 2

Type 2 respiratory failure is caused by increased airway resistance; both oxygen and carbon dioxide are affected. Defined as the build up of carbon dioxide levels (P_aCO₂) 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).

The basic defect in type 2 respiratory failure is characterized by:

PaO2	decreased
PaCO2	increased
PA-aO2	normal
pH	decreased

[edit] Causes

• Pulmonary dysfunction
  • Asthma
  • Emphysema
  • Chronic Obstructive Pulmonary Disease
  • Pneumonia
  • Pneumothorax
  • Pulmonary contusion^[1]
  • Hemothorax
  • Acute Respiratory Distress Syndrome (ARDS) is a specific and life-threatening type of respiratory failure.
  • Cystic Fibrosis
• Cardiac dysfunction
  • Pulmonary edema
  • Cerebrovascular Accident
  • Arrhythmia
  • Congestive heart failure
  • Valve pathology
• Other
  • Fatigue due to prolonged tachypnoea in metabolic acidosis
  • Intoxication with drugs (e.g. morphine, benzodiazepines) that suppress respiration.
  • Neurological Disease
  • Toxic Epidermal Necrolysis

[edit] Treatment

Emergency treatment follows the principles of cardiopulmonary resuscitation. Treatment of the underlying cause is required. Endotracheal intubation and mechanical ventilation may be required. Respiratory stimulants such as doxapram may be used, and if the respiratory failure resulted from an overdose of sedative drugs such as opioids or benzodiazepines, then the appropriate antidote such as naloxone or flumazenil will be given.

[edit] See also

• Ventilation/perfusion ratio
• Pulmonary shunt

[edit] References

v • d • e Pathology of respiratory system (J, 460-519), respiratory diseases Upper RT (including URTIs, Common cold) Head sinuses: Sinusitis nose: Rhinitis (Vasomotor rhinitis, Atrophic rhinitis, Hay fever) · Nasal polyp · Rhinorrhea · nasal septum (Nasal septum deviation, Nasal septum perforation, Nasal septal hematoma) tonsil: Tonsillitis · Adenoid hypertrophy · Peritonsillar abscess Neck pharynx: Pharyngitis (Strep throat) larynx: Laryngitis · Croup · Laryngospasm · vocal folds: Vocal fold nodule · epiglottis: Epiglottitis trachea: Tracheitis · Tracheal stenosis Retropharyngeal abscess Lower RT/lung disease (including LRTIs) Bronchial/ obstructive acute: Acute bronchitis chronic: COPD (Chronic bronchitis, Emphysema, Diffuse panbronchiolitis) · Asthma (Status asthmaticus) · Bronchiectasis unspecified: Bronchitis · Bronchiolitis (Bronchiolitis obliterans) Interstitial/ restrictive External agents/ occupational lung disease Pneumoconiosis (Asbestosis, Baritosis, Bauxite fibrosis, Berylliosis, Caplan's syndrome, Chalicosis, Coalworker's pneumoconiosis, Siderosis, Silicosis, Byssinosis) Hypersensitivity pneumonitis (Bagassosis, Bird fancier's lung, Farmer's lung) Other ARDS · Pulmonary edema · Löffler's syndrome/Eosinophilic pneumonia · Respiratory hypersensitivity (Allergic bronchopulmonary aspergillosis) Hamman-Rich syndrome · Idiopathic pulmonary fibrosis · Sarcoidosis Obstructive or restrictive Pneumonia/ pneumonitis By pathogen Viral · Bacterial (Pneumococcal, Klebsiella) / Atypical bacterial (Mycoplasma, Legionnaires' disease, Chlamydiae) · Fungal (Pneumocystis) · Parasitic · noninfectious (Chemical/Mendelson's syndrome, Aspiration/Lipid) By vector/route Community-acquired · Healthcare-associated · Hospital-acquired By distribution Broncho- · Lobar IIP UIP · DIP · BOOP-COP · NSIP · RB Other Atelectasis · circulatory (Pulmonary hypertension, Pulmonary embolism) · Lung abscess Pleural cavity/ mediastinum Pleural disease Pleuritis/pleurisy Pneumothorax/Hemopneumothorax (Tension pneumothorax) Pleural effusion: Hemothorax · Hydrothorax · Chylothorax · Empyema/pyothorax · Malignant Fibrothorax Mediastinal disease Mediastinitis · Mediastinal emphysema Other/general Respiratory failure · Influenza · SARS · Idiopathic pulmonary haemosiderosis · Pulmonary alveolar proteinosis respiratory system navs: anat nose,larynx/lower+thoracic cavity/physio/dev, noncongen/congen/tumors, symptoms+signs/eponymous, proc

v • d • e Organ failure General Heart failure · Respiratory failure · Liver failure (Acute liver failure) · Renal failure (Acute renal failure, Chronic renal failure ) Multiple Multiple organ dysfunction syndrome

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