Pacey's Paste for Easy Topicalization of the Upper Airway.
There are numerous invasive and non-invasive methods of application of Local Anesthesia to the OroPharynx and Glottis and all of these have their devotee's. The classic methods use a nebulizer with a bulb attached and spray Novocaine or local mixed with Epinephrine through a stiff metal wand as you go into the airway.
There are Xylocaine Pressurized spray devices available as well but often the spray via a flexible and breakable plastic wand as well. These are often used for spraying cords during induction where a Direct Laryngoscope is being used.
The failure of these methods is most pronounced when you need them most in the
challenging difficult airway scenario. Failure leads to spotty application which is most heavily applied in the oropharynx and tongue but is less efficiently applied in the hypo pharynx area. The result of this distribution is that when tools get close to the Glottis the patient may respond with reflex protective neck muscle activation and a battle can then ensue between the determined airway manager and the equally determined distressed patient.
Strategies designed to avoid maldistribution of Local anesthetic.
The MAD ( Mucosal Atomizer Device) Device is an attempt to avoid maldistribution by use of a flexible wand that can pass down in the awake patient into the hypo-pharynx closer to the area of need. This device has many devotees and has become more popular recently.
Direct placement of local by a trans-cricothyroid membrane route has also been done to at once identify this membrane and the trachea while it also applies local anesthetic to the cord region and perhaps also the Glottic entrance such that it may suppress laryngo-spasm or discomfort of tube passage.
Percutaneous injections directed at the Supra-Laryngeal nerve supply of the larynx via bi-lateral infiltration of the neck have also been used at times, but have several problems. Hitting the target can be challenging in the more obese patient, where the need is great, because the greater cornua of the hyoid may be poorly defined. The neck also has tissue planes that channel the injected material in uncertain paths leading to spotty topicalization. The injection of larger amounts of xylocaine and adrenaline can also cause swelling of the peri-glottic tissues which could lead to poorer visualization.
Pacey's Paste Method of disseminated topicalization of the Pharynx and Larynx.
The above methods are in themselves sub optimal and therefore generate consternation and debate about how one may consistently topicalize the area. The method that I learned from an American Anesthesiologist was ideal for my practice of upper GI endoscopy where passage of a 10-12 mm gastroscope was necessary. Following IV Versed and Small doses of IV fentanyl this method was applied.
The dose was prepared by connection of 2 10 CC syringes to a standard 3 way iv tubing stop cock. Then 7 cc of Viscous 2% Lidocaine and 3 cc air were drawn into one syringe and 7cc of 2% lidocaine with 3 cc air was passed into the second syringe. With the valve turned to allow passage back and forth to these syringes a mixing of the air with these 2 forms of lidocaine was carried out to produce an airway slime that had 14cc of 2% lidocaine content. this was instilled into the mouth in 2 aliquots while other preparations were carried out. After a few minutes this frothy slime could be seen in all recesses of the pharynx and even down to the stomach. The bubbles accumulated in the glottic entrance as well. Thus the even distribution was obvious on each occasion. The gastroscope is a large intrusion device and passage was encouraged by the very slippery slimy bubbles and lidocaine.
Because I used this regularly in a busy endoscopy practice the efficiency of the method was confirmed. Because this was done in a formal endoscopy clinic the nursing staff were able to set up and mix the solution of air bubbles, Lidocaine Viscous, and Lidocaine Liquid prior to each case and on occasion do the topicalization procedure itself.
