We will now review LMA insertion technique. The overarching goal of insertion is to achieve and maintain a viable augmented airway, which permits adequate delivery of oxygen to the patient. This goal can be broken down into the following four key elements (4 Ps):
- Provide unrestricted oxygenation and ventilation
- Permit spontaneous or mechanical (positive pressure) ventilation
- Pressures – achieve an adequate primary (laryngeal) and secondary (oesophagealThe oesophagus is the hollow tube that leads from the throat (pharynx) to the stomach.) seal. Aim:
- Oropharyngeal leak pressureOropharyngeal leak pressureOropharyngeal leak pressure (OLP), measured by closing the expiratory valve of the anesthetic circle system at a fixed gas flow rate and noting the equilibrium airway pressure, is used to quantify the efficacy of airway sealing in SGA devices. > 20cm H2O
- Oesophageal seal of 40-60cm H2O or one sufficient enough to prevent aspiration
- Achieve both seals using an intracuff (inflation) pressure of ≤ 60cm H2O to avoid excessive compression of surrounding structures
- Protect surrounding upper airway structures for LMA-induced trauma, in particular the teeth and posterior pharyngeal wall.