From the Guidelines
Auto-PEEP should be managed by adjusting ventilator settings to allow more time for exhalation, including decreasing respiratory rate, reducing tidal volume, and increasing inspiratory flow rate, as recommended by the most recent guidelines 1. To manage auto-PEEP, it is essential to first identify its presence by performing an end-expiratory hold maneuver on the ventilator.
Key Management Strategies
- Decrease respiratory rate to allow more time for exhalation
- Reduce tidal volume to minimize air trapping
- Increase inspiratory flow rate to reduce inspiratory time
- Consider decreasing the I:E ratio to 1:3 or greater in severe cases
- Use bronchodilators such as albuterol or ipratropium to reduce airway resistance in patients with obstructive lung disease
- Apply external PEEP to splint airways open during exhalation, starting at 50-85% of measured auto-PEEP
- Sedation may be necessary to reduce respiratory drive and patient-ventilator dyssynchrony Auto-PEEP is a critical condition that can increase intrathoracic pressure, potentially causing decreased cardiac output, barotrauma, and ventilator dyssynchrony, making prompt recognition and management essential for patient safety, as highlighted in recent studies 1.
Importance of Prompt Recognition and Management
- Auto-PEEP can lead to serious complications if left unmanaged
- Prompt recognition and management can improve patient outcomes and reduce morbidity and mortality
- Recent guidelines emphasize the importance of adjusting ventilator settings to manage auto-PEEP and prevent complications 1
From the Research
Definition and Causes of Auto-PEEP
- Auto-positive end-expiratory pressure (auto-PEEP) is a physiologic event that occurs in mechanically ventilated patients, commonly found in acute severe asthma, chronic obstructive pulmonary disease, or patients receiving inverse ratio ventilation 2.
- Factors predisposing to auto-PEEP include a reduction in expiratory time by increasing the respiratory rate, tidal volume, or inspiratory time 2.
Detection and Measurement of Auto-PEEP
- Auto-PEEP can be detected and quantified by a simple bedside maneuver: expiratory port occlusion at the end of the set exhalation period 2.
- In patients receiving controlled mechanical ventilation, auto-PEEP can be estimated by measuring the rise in airway pressure during an end-expiratory occlusion maneuver 3.
- In patients who trigger the ventilator or who are not connected to a ventilator, auto-PEEP can be estimated by simultaneous recordings of airflow and airway and esophageal pressure, respectively 3.
Consequences and Treatment of Auto-PEEP
- Auto-PEEP predisposes the patient to increased work of breathing, barotrauma, hemodynamic instability, and difficulty in triggering the ventilator 2.
- Strategies that may reduce auto-PEEP include reduction of minute ventilation, use of small tidal volumes, and prolongation of the time available for exhalation 3.
- The application of low-levels of external PEEP can reduce dyspnea, reduce work of breathing, improve patient-ventilator interaction, and cardiac function, all without worsening hyperinflation 3.
- Neurally adjusted ventilatory assist, a novel strategy of ventilatory assist, may improve patient-ventilator interaction in patients with auto-PEEP 3.
- Providing external PEEP to 75-80% of auto-PEEP in patients who are spontaneously breathing during mechanical ventilation can decrease the work of breathing 2.
Monitoring and Management of Auto-PEEP
- Routine monitoring for auto-PEEP in patients receiving controlled ventilation is recommended 2.
- Ventilator graphics are invaluable for monitoring and treatment decisions at the bedside 4.
- The electrical activity of the diaphragm (EAdi) signal can be reliably used to estimate auto-PEEP in patients undergoing pressure support ventilation and neurally adjusted ventilatory assist (NAVA) 5.