Der Anaesthesist
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Randomized Controlled Trial
Spontaneously breathing anesthetized patients with a laryngeal mask airway: positive end-expiratory pressure does not improve oxygen saturation.
Spontaneous ventilation is a popular mode of ventilation for patients with the laryngeal mask airway (LMA). Studies have shown, however, that spontaneous ventilation impairs gas exchange and that assisting or controlling ventilation results in higher oxygen saturation. Atelectasis during general anesthesia is a well described mechanism which impacts on gas exchange. ⋯ The application of a PEEP of +7 cm H₂O with a LMA under spontaneous ventilation cannot be recommended. Limitations of our study were the selection of healthy patients and omitting pre-oxygenation before induction which might have limited the development of atelectasis. In addition arterial partial pressure of oxygen (p(a)O₂) measurements could have revealed subtle changes in oxygenation.