PEEP and Mechanical Ventilation: We Are Warned, We Cannot Ignore—Reply

In reply:

We are grateful to Dr Appendini and colleagues for their comment and appreciation.

The similar expiratory time used in patients with high and low auto-PEEP levels does not diminish the lack of relationship between auto-PEEP and expiratory time (if anything, it made the statistical analysis more consistent).

We definitely believe that the ventilator settings could have been improved in some subjects enrolled in the study. Namely, expiratory time should be increased in patients with significant levels of auto-PEEP. Our findings suggest that such an increase should be proportional to the time constant of the respiratory system.

Therefore, we agree with Appendini and colleagues that in some cases, breathing pattern manipulation (ie, the decrease of breathing frequency and/or inspiratory time) could be advisable in mechanically ventilated patients with auto-PEEP.

On the other hand, we should always keep in mind that expiratory time can be set only in patients undergoing controlled ventilation, whereas it cannot be imposed during any modality of assisted ventilation, when expiration is ended by patient inspiratory triggering. On the contrary, medical therapy and patient position can effectively reduce auto-PEEP both during controlled and during assisted ventilation and therefore play a fundamental role in clinical practice, in particular during weaning from mechanical ventilation.

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