Friday, September 30, 2016

Pacey's Paste Method of Application Local Anesthesia to the Pharynx, and Glottis.

                               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.


Success of Intubation Rescue Techniques After Failed Direct Laryngoscopy in Adults: A Retrospective Comparative Analysis From the Multicenter Perioperative Outcomes Group

Aziz MF, Brambrink AM, Healy DW, et al
Anesthesiology. 2016 Aug 1. [Epub ahead of print]
Study Summary
A team of investigators retrospectively analyzed 346,861 anesthesia cases that involved attempted tracheal intubation from 2004 to 2013 at seven academic centers. Of these, 1427 patients (0.41%) had a failed direct laryngoscopy, leading to 1619 subsequent intubation attempts.
The majority of these rescue attempts (69%) were managed with video laryngoscopy, followed in frequency by flexible fiberoptic (11%), lighted stylet (8%), supraglottic airway as part of an exchange technique (5%), or optical stylet (0.6%). More than 1000 anesthesia providers (353 attending anesthesiologists, 449 residents, and 207 certified registered nurse anesthetists) managed these rescues after being unable to intubate the trachea with a traditional laryngoscope.
The study's main take-home message was that video laryngoscopy had the highest intubation success rate (92%), with the GlideScope® (Verathon; Bothell, Washington) the most commonly used video laryngoscope device (89% of the time). The intubation success rate for rescue was 78% for both the supraglottic airway conduit and flexible bronchoscopic intubation, followed by 77% for lighted stylet and 67% for optical stylet.
Viewpoint
Inability to intubate the trachea after induction of general anesthesia is an outcome anesthesiologists aim to avoid. Although there are patient characteristics that can be used to help predict who will have a difficult airway, there is no 100% sensitive or specific prediction tool. As a result, clinicians will encounter unexpectedly difficult airways to intubate, as this study's 0.41% incidence rate suggests. Any study that sheds light on the use and success rates of rescue techniques after failed direct laryngoscopy in adult surgical patients will therefore be priority reading for clinicians.
For the past half-century, the most common method for intubation was to insert a laryngoscope (which consists of a handle and either a curved or straight stainless steel blade with a light source) into the oropharynx, so that the vocal cords are directly visualized. In contrast, the video laryngoscope has a digital camera on the blade. This means that the clinician does not directly view the larynx, but rather sees it indirectly on a screen.
In this study, 89% of rescues used the GlideScope video laryngoscope, which has a different (ie, 60°) angulation of its blade without the usual need for anterior displacement of the lower jaw. This helps improve the view of the larynx, which is projected onto an external liquid crystal display screen mounted on a separate stand.
The authors found that the use of video laryngoscopy for rescue of failed direct laryngoscopy increased from 30% in 2004 to more than 80% in 2012. This is not an unexpected result. As video laryngoscopy technology has become more widely available in surgery suites across the country, anesthesia providers have been able to gain experience and comfort with the available devices.
This study's main finding builds on the growing literature supporting the usefulness of video laryngoscopy in clinical anesthesia care. In fact, the study showed that more than 90% of the time when intubation was not possible with the traditional direct laryngoscope, the newer video laryngoscope proved to be helpful.

The very large sample size of this study (>300,000 cases) is a nice example of the kind of pooled data research made possible by the Multicenter Perioperative Outcomes Group, a consortium of institutions formed in 2008 with a shared data set facilitating the investigation of perioperative outcomes.
It is quite likely that video laryngoscopy devices, with their improved optics, will increasingly replace traditional direct laryngoscopy in routine airway management.