Respiratory Failure

Respiratory Failure

                                          Respiratory failure occurs when the respiratory system fails in either one or both of its gas exchange functions: oxygenation and the elimination of carbon dioxide. A reduction in the oxygen carried in the bloodstream is referred to as hypoxaemia, and a rise in the carbon dioxide levels within the bloodstream is referred to as hypercapnia.

Respiratory failure is classified into two groups

•  Type I respiratory failure
•  Type II respiratory failure

 Type I respiratory failure

                                                              Type I respiratory failure occurs when there is a problem with oxygenation resulting in hypoxaemia. This is most commonly caused by ventilation/perfusion mismatch resulting in reduced diffusion of oxygen from the alveoli into the pulmonary circulation. Type I respiratory failure is characterized by

      

      

Type II respiratory failure 

                                                              Type II respiratory failure occurs when there occurs when there is inadequate alveolar ventilation resulting in hypoxaemia and hypercapnia. Type II respiratory failure is characterized by

       

 

                                                                          Type II respiratory failure can be further sub-classified depending on the pre-existing condition of the patient and the speed of onset

Acute type II respiratory failure

                                                                        The patient will have no, or minor, evidence of pre-existing respiratory disease and patients typically have a high PaCO2, low pH, and normal bicarbonate.

Chronic type II respiratory failure

                                                                        Evidence of chronic respiratory disease, high PaCO2, normal pH, and high bicarbonate (>26 mmol/l).

Acute-on-chronic type II respiratory failure

                                                                            An acute deterioration in an individual with significant pre-existing type II respiratory failure, high PaCO2, low pH, and high bicarbonate (>26 mmol/l).