Topical Airway Anesthesia for Awake-endoscopic Intubation Using the Spray-as-you-go Technique with High Oxygen Flow

The overall goal of the spray-as-you-go technique is to provide sufficient topical anesthesia during intubation with higher patient satisfaction and better compliance than the classical bolus application of anesthetics. The main advantage of this technique is that the oxygen flow atomizes the local anesthetic into fine particles, which evokes less coughing and therefore patients are more satisfied and cooperative. We had the idea for using this method when we were struck by the patients complaining that the splash of the bolus striking the airway mucosa gave them the feeling of being drowned.

To begin, apply a one milliliter mixture of two percent lidocaine with 0.25%phenylephrine to each nostril. Then, apply a local anesthetic such as by spraying 10%lidocaine directly onto the mucosa of the oral pharynx twice from the tip to the back of the tongue. Ask the patient to gargle the lidocaine for as long as possible.

In preparation, have ready an inspected, undamaged atomizer ready for its intended one time use. Assemble and check a flexible intubation endoscope and then railroad a suitably sized cuffed and lubricated flexible endotracheal tube over the endoscope. Then, connect the oxygen tube of the atomizer directly to the oxygen flow meter without a humidifier bottle, as they are incompatible with the atomizer.

Next, attach the connecting tube from the atomizer to the lower tape on the working channel of the endoscope. Then set the oxygen flow rate to 10 liters per minute. Now, connect a one milliliter syringe containing two percent lidocaine to the three-way side arm fitting and proceed with the technique.

The challenge of this technique is the correct execution of delivering the lidocaine to the atomizer. Closing and releasing of the pressure control channel have to be properly timed. First, deliver the prepared dose of two percent lidocaine to the atomizer while closing the flow control opening by finger and rapidly injecting the medication.

Then, immediately release the flow. The use of a high oxygen flow allows fogging of the local anesthetic into fine particles. Now begin advancing the flexible endoscope in the airway while injecting the local anesthetic via the atomizer along the inside of the nostril, along the posterior nares, the epiglottis, the glottis, and the vocal cords.

Before passing the endoscope past the vocal cords, wait two minutes for the anesthesia to take effect. Next, advance the endoscope carefully through the glottis into the trachea, and position the tip just above the carina. Be careful to not advance to the main stem of the bronchus.

Railroad the tube into the trachea using rotation. Now remove the endoscope, leaving the endotracheal tube in place. The described awake flexible endoscopic intubation was successfully performed on 47 of 48 patients, barring one who suffered from a stenosing tumor of the pharynx.

On an 11 point scale from not unpleasant to intolerable, the patients rated the experience as a one and the hospital staff rated it a two. Overall, the procedure was well-received. In addition to these vital parameters, the main duration of the intervention was five minutes and the average amount of 2%lidocaine atomized during was 100 milligrams.

The median number of coughs in a control group using the classical bolus application of two times five milliliters two percent lidocaine, was nearly twice as high. Once mastered, the technique can ease and accelerate the procedure of awake fiber-optic intubation. It must be considered that the attended time heavily depends on the expertise of the operator and the level of difficulty of the patient's airway.

A major challenge is to ensure that the procedure is comfortable for the patient in order to enable optimal intubation conditions, while the patient continues to breathe spontaneously. The atomizer is a useful tool in an emergency setting. The preparation of the set needs less than a minute, and the user needs no special training.

It might also be a valuable feature to facilitate endoscopic bronchoscopy. Don't forget that working with a constant oxygen flow includes potential complications, like gastric insufflation, organ rupture, and bowel trauma. By using the flow control opening of the atomizer, these complications can be avoided.