RT Book, Section A1 Greenberg, Robert D. A1 McConnell, Stephen A2 Cooney, Derek R. SR Print(0) ID 1126791359 T1 Respiratory Failure and Anaphylaxis T2 Cooney's EMS Medicine YR 2016 FD 2016 PB McGraw-Hill Education PP New York, NY SN 9780071775649 LK accessemergencymedicine.mhmedical.com/content.aspx?aid=1126791359 RD 2024/03/29 AB Respiratory failure is the inability of the lungs to perform the vital function of gas exchange, and may be caused by an inability to either obtain sufficient oxygen or eliminate carbon dioxide. Numerically, respiratory failure may be defined on arterial blood gas measurement as hypoxemia, with a PaO2 45 mm Hg.1 Acute respiratory failure may be divided into four types. Type 1 respiratory failure is caused by acute hypoxia, and may be seen in patients with pulmonary edema, pneumonia, pulmonary hemorrhage, or acute respiratory distress syndrome. Type 2 respiratory failure may be seen with hypoventilation and an inability to rid the body of carbon dioxide. Examples of disease processes where this may be seen include central nervous system disorders where the respiratory drive is diminished, neuromuscular disorders where the muscles of respiration are not sufficiently able to produce ventilation, as well as in pulmonary conditions such as pneumothorax, airway obstruction, or pleural effusions. Significant atelectasis is the cause for Type 3 respiratory failure, and is most commonly seen after mechanical ventilation. Type 4 respiratory failure is seen in patients who have hypoperfusion of the muscles of respiration caused by another process, such as shock.2 Identifying the incidence of acute respiratory failure in the United States is extremely difficult but has been estimated near 140 cases per 100,000 individuals over the age of 5. Of the patients with acute respiratory failure, approximately 36% will not survive to hospital discharge. There seems to be a correlation with increased mortality seen in patients with increase in age, presence of multisystem organ failure, cancer, underlying liver disease, and HIV infection.3