Positive end-expiratory pressure

A positive end-expiratory pressure ( PEEP abbreviation for positive end- expiratory pressure ) denotes an artificially generated during ventilation in the lung positive pressure applied after completion of the exhalation ( expiration). This pressure increases the mean airway pressure and functional residual capacity. PEEP may help to prevent a collapse of the alveoli, the alveoli, and thus prevents atelectasis before. In addition, the oxygen saturation of the blood can be improved in many cases.

In almost any mechanical ventilation, a moderate PEEP is used, at least, for example, when drowning or diving accident, as well as smoke or carbon monoxide poisoning. Even when the so-called PEEP edema is used.

By increasing the pressure in the chest cavity reduces the PEEP venous return of blood to the heart, so that the cardiac output may decrease. Conversely, a damming into upper and lower vena cava, with corresponding increases in pressure in the upstream organs. Depending on the level of PEEP, this may result in damage and function limitations of brain, liver, kidneys and other organs.

In operations on the neck ( Strumaresektion, thyroidectomy, carotid desobliteration etc. ) prevents the ingress of air into PEEP accidentally opened large veins and thus the dangerous air embolism.

Relative contraindications for PEEP are obstructive respiratory diseases which tend to form an intrinsic Peep, such as asthma. Since the Exspirationzeit not sufficient by airway obstruction for a complete pressure equalization in the alveoli beyond the constriction, a positive pressure is maintained.

Modern ventilators provide detailed set-up and measurement capabilities for PEEP. In some models of resuscitators a simple PEEP valve is present or it is possible to connect a PEEP valve.

For use in patients without adequate protective reflexes of the airway by endotracheal intubation or comparable procedures must be secured. Otherwise there is a risk of vomiting and aspiration due to overinflation of the stomach. In the awake patient can be used for example as part of the CPAP mask a mask. Reservoir is also, albeit much lower, the risk of gastric insufflation. With careful adaptation of the systems, but the disadvantages of the positive pressure in the exhalation are outweighed by advantages.

Benefits

  • Increase in the functional residual capacity, thereby increasing the gas exchange surface, ventilation-perfusion ratio, decreased intrapulmonary shunts, increased oxygenation
  • Prevention of atelectasis
  • Improvement in lung compliance
  • Reduction of pulmonary edema

Disadvantages

  • Risk of barotrauma at too high a level of PEEP
  • Increased right ventricular afterload
  • Increase in intracranial pressure
  • Ventilation pattern
Compliance (physiology)
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