Lately, I have seen some threads discussing whether it is safe to use LMA with Peep. I remember when I was in school, some of the preceptors would take out the PEEP after I inserted the LMA. The reasons they gave me were insufflations of stomach. But in the back of my mind, I wondered whether it holds true with our modern devices.
Airway resistance and compliance are the two important factors to determine the safety of LMA with PPV. A recent study by Devitt et al demonstrated that LMA with PPV can be used safely in patients with normal airway resistance and compliance (<20 cmH2O) to produce normal tidal volumes. In addition, Keller’s work substantiated that gastroesophageal insufflations would not be a problem if ventilation pressures are lower than 20 cmH2O. Furthermore, LMA with pressure support ventilation and PEEP of 5 cmH2O provides better gas exchange than does spontaneous breathing with continuous positive airway pressure (CPAP) in obese patients (BMI>30) whereas in normal BMI patients, no difference was found with or without PEEP in SpO2.
We know LMA-ProSeal® (PLMA) has a more effective seal of the airway than the LMA-Classic™ (CLMA) and the ventilation pressure can go as high as 30cm H2O. Similarly, the supreme LMA can also form an effective seal with pressure up to 30cmH2O. The newer LMAs form much better seal with higher ventilation pressure compared to the old reuseable LMAs. Before you use the LMA, look at the insert of the LMA packaging, you may find that the seal pressure mostly higher than 20cm H2O with the newer LMAs. As the studies have shown that PPV is strongly supported as a safe practice.
ProSeal™laryngeal mask in normal weight and obese patients : oxygenation under pressure-controlled ventilation and different end-expiratory pressures. Anaesthesist. 2011 Oct;60(10):908-15. doi: 10.1007/s00101-011-1926-8. Epub 2011 Jul 29.
Devitt JH, Wenstone R, Noel AG, O’Donnell MP. The laryngeal mask airway and positive-pressure ventilation. Anesthesiology. 1994;80:550–555.
Brimacombe J, Keller C, Hörmann C. Pressure support ventilation versus continuous positive airway pressure with the laryngeal mask airway: a randomized crossover study of anesthetized adult patients. Anesthesiology. 2000;92:1621–1623.