Rome, Italy
LMA® is the property of Intavent Limited.
EditorThe Cobra Perilaryngeal Airway (PLA)TM is a new supraglottic device,1 which consists of a tube with an inflatable cuff and a 15 mm standard adaptor. The softened distal end (CobraPLATM head) of the breathing channel is designed to be positioned in the hypopharynx, opposite the laryngeal inlet, to divert the inspiratory gas into the trachea through the slotted openings (Fig. 1).
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CobraPLATM insertion was possible in 100% of patients. It was considered easy (no tactile resistance or minimum tactile resistance) in 85/110 (77.3%), difficult (necessary to perform jaw trust or neck hyperextension) in 25/110 (22.7%) patients, and impossible in none. In 48/110 patients, a size 3 CobraPLATM was inserted, in 62/110 a size 4. After insertion, adequate ventilation and a satisfactory seal were verified. We documented airway sealing pressures by closing the expiratory valve of the circular breathing system and noting the airway pressure at which a leak was heard, using a stethoscope placed on the neck. All patients were artificially ventilated through the CobraPLATM. In 56/110 (51%) patients there was a leak, although the cuff was inflated with the maximum volume indicated by the manufacturers: size 3 <65 ml, size 4 <70 ml, and 5 < 85 ml. In these patients, the device was removed and a larger size of CobraPLATM was inserted. In 23 of the 48 patients in whom a size 3 CobraPLATM was inserted (mean (SD) weight: 65.1 (3.6) kg, 95% CI 62.367.8), a size 4 was used successfully. In 33 of the 62 patients in whom a size 4 CobraPLATM was inserted (weight 82.3 (3.4) kg, 95% CI 81.083.5), a size 5 was used successfully.
As a result, a good seal (leak pressure 34.2 (2.8) cm H2O) was obtained using a size 3 CobraPLATM in 25/110 patients (22.7%) who weighed 55.5 (3.6) kg (95% CI 53.956.9), a size 4 CobraPLATM in 52/110 (47.3%) with a weight of 70.2 (7.2) kg (95% CI 68.272.2), and a size 5 in 33 /110 (30%) with a weight of 82.3 (3.5) kg (95% CI 81.083.5). Cuff inflation volumes were 26.5 (2.1) ml for size 3; 31.9 (4.0) ml for size 4; and 40.0 (4.1) ml for size 5.
The mean time of insertion was 6.8 (2.0) s, which is shorter than that required to insert the laryngeal tube and LMA ProSeal.2 No adverse airway events occurred and gastric inflation was not detected by auscultation over the epigastrium, in any patient. The mean time of artificial ventilation through the CobraPLATM was 75 (12) min.
These preliminary results suggest that the CobraPLATM is easy to place blindly, allowing a rapid achievement of adequate oxygenation. In contrast to the recommendations of the manufacturers, we suggest the following range for choosing the size of CobraPLATM: size 3 for patients <60 kg; size 4 between 6080 kg; and size 5 >80 kg. When using this range, the cuff inflation volume is much reduced from the maximum recommended by the manufacturer.
F. Agrò
G. Barzoi
B. Gallì
Rome, Italy
References
1 Agrò F, Barzoi G, Carassiti M, Gallì B. Getting the tube in the oesophagus and oxygen in the trachea: preliminary results with the new supraglottic device (CobraPLATM) in 28 anaesthetised patients. Anaesthesia 2003; 58: 9201[CrossRef][ISI][Medline]
2 Cook TM, McKinstry C, Hardy R, Twigg S. Randomized crossover comparison of the ProSealTM laryngeal mask airway with the Laryngeal Tube® during anaesthesia with controlled ventilation. Br J Anaesth 2003; 91: 67883