Positive End-Expiratory Pressure

1. Indications
   1. Pulmonary condition with widespread alveolar collapse
   2. Adult Respiratory Distress Syndrome (ARDS)
      1. PEEP increases lung compliance
      2. PEEP decreases intrapulmonary shunting
      3. Increases PO2 and allows lower FIO2 below 60%
      4. May increase dead space ventilation
         1. Overdistends normal lung
   3. Pulmonary Edema
      1. PEEP allows decrease in FIO2 below 60%
      2. PEEP may increase extravascular lung water
2. Disproved uses of PEEP
   1. Localized Lung Disease (e.g. lobar Pneumonia)
      1. PEEP may worsen Hypoxemia
         1. Overdistends normal lung
         2. Directs blood flow to diseased lung
      2. PEEP not recommended
         1. Unless selectively applied to diseased lung
   2. Prophylactic PEEP
      1. PEEP does not reduce ARDS Incidence
   3. Routine PEEP
      1. PEEP does not appear indiscriminately beneficial
   4. Mediastinal Bleeding
      1. PEEP does not protect against mediastinal bleeding
3. Physiology
   1. PEEP maintains small end-expiratory pressure
      1. Helps to prevent alveolar collapse
      2. Promotes alveolar-capillary gas exchange
   2. Increases lung function parameters
      1. Increases Functional Residual Capacity (FRC)
   3. Increases cardiac output with low airway pressures
      1. May result in increased Oxygen Delivery
4. Dosing
   1. Usual PEEP setting: 5 to 10 cm H2O
5. Complications
   1. Decreased cardiac output
      1. Associated with higher airway pressures
      2. Associated with decreased ventricular filling
   2. Barotrauma
   3. Fluid Retention
   4. Intracranial Hypertension
6. References
1. Marino (1991) ICU Book, Lea & Febiger, p. 375-9

sources from ：http://www.fpnotebook.com/lung/procedure/PstvEndExprtryPrsr.htm