Facts. I can't find a King LTSD size 4 for an average sized female few nights ago. I was taught by an anesthesiologist from Wisconsin. Adrian Matioc.
He advocates the King LTSD as a rescue oxygenation device. Declared it the weapon of choice against the BoogeyMan of airways, Lingual Tonsillar Hyperplasia.
The distance between the Esophageal Cuff and the Base of Tongue Cuff is the same for these 2 different sized Laryngeal Tubes. This means I can use a size 5 which is usually for patients sized over 6 feet tall on patients who by average are between 5 and 6 feet tall. I wouldn't recommend trying to use a shorter King LTsd sized 4 for a patient much taller who would deserve a size 5 King LTSD.
See the video below to appreciate this fact.
If one wanted to be cheap, buy only size 3 and size 5 and you will get away with treating most adult airways needing an appropriate sized Supraglottic devices for Rescue Oxygenation.
Wise men Publish to show the world they read and know things. Some more than others.
1. Use of the Laryngeal Tube in two unexpected difficult airway situations: lingual tonsillar hyperplasia and morbid obesity.Matioc AA, Olson J.Can J Anaesth. 2004 Dec;51(10):1018-21.PMID: 15574554
2. "The critical airway".Matioc AA, Arndt G.Can J Anaesth. 2005 Nov;52(9):993-5. No abstract available. PMID:16251570
3. The critical airway: the difficult airway in the adult critical care.Matioc AA, Arndt G, Jofee A.Crit Care Med. 2009 Mar;37(3):1175-6. doi: 10.1097/CCM.0b013e3181986ec0. No abstract available. PMID: 19237959
4. The laryngeal tube and pharyngeal mucosal pressure.Matioc AA, Arndt G.Can J Anaesth. 2003 May;50(5):525-6; author reply 526. No abstract available. PMID: 12734171
5. The "bouncing sign" may optimize the insertion of the laryngeal tube.Matioc AA.Can J Anaesth. 2004 Mar;51(3):278-9. No abstract available. PMID: 15010418