Surgical airway.

Close to 3% of all intubation attempts are considered difficult airways, for which a plan for a surgical airway should be considered. Our article provides an overview of the different types of surgical airways. This article provides a comprehensive review of the main types of surgical airways, relevant anatomy, necessary equipment, indications and contraindications, preparation and positioning, technique, complications, and tips for management. It is important to remember that the placement of a surgical airway is a lifesaving procedure and should be considered in any setting when one "cannot intubate, cannot ventilate".

INTRODUCTION

The number one priority is always the airway. A surgical airway should be considered when endotracheal intubation is not an option or fails. In the past, the primary reason for the placement of a surgical airway was emergent due to an impending airway obstruction, inability to intubate, or inability to ventilate with a bag mask.[1] Now, elective placement is much more common. Also, there are several instances where the placement of a surgical airway is recommended, especially in the setting of large tumors of the upper aerodigestive tract, laryngotracheal injuries that preclude intubation, inflammatory swelling of the upper airway, bleeding in the airway, maxillofacial trauma, bilateral vocal cord immobility, and so on. Furthermore, in settings of known difficulty with intubation or certain facial dysmorphisms, an elective surgical airway is ideal.

HISTORY

Any discussion of surgery from the ancient Egyptian times must include the possibility of the placement of a surgical airway, or tracheotomy. Dating back 5,000 years, Egyptian hieroglyphs portray images suggestive of this procedure with sharp pointed instruments directed at the lower neck region.[23] There were multiple references regarding performing a tracheotomy in the historical writings of the Rig Veda in the Hindu culture as well as the Ebers Papyrus.[4] The term ‘tracheotomy’ was first published in 1649 by Thomas Fienus, and referred to the creation of an opening into the anterior tracheal wall to secure the airway. However, in 100 BC, Asclepiades of Bithynia was noted to be the first surgeon to perform an elective tracheotomy, but the first documented successful case dates back to 1546 and is accredited to Antonio Musa Brassavola, as the patient was thought to have an ‘abscess of the windpipe’. Traditionally, the use of a tracheotomy was reserved for cases of airway obstruction.[5]

In the early 19th century, tracheotomy was employed in the treatment of diphtheria and other infectious causes which lead to airway obstruction. In the 1930s, tracheotomy was performed in patients with bulbar poliomyelitis to facilitate access to the airway for the removal of secretions.[6] In the late 1940s to the early 1950s, many began trialing the application of positive pressure ventilation through a tracheotomy.[7] Also, in the 1950s, this surgical procedure was extended to multiple neurologic disorders including coma, brain tumors, multiple sclerosis, and so on.[67] This growing use led to many considering it to be a routine procedure that was both effective and relatively safe, which sharply contrasts much of the previous thought equating tracheotomy to a ‘pronouncing sentence of death’.[8]

ANATOMY

The discussion of any surgical airway would require a brief review of the anatomy of the larynx. Superiorly, the epiglottis sits at the level of the hyoid bone, below which lies the thyroid cartilage. These two structures are separated by the thyrohyoid membrane. The true vocal cords are located at the level of the thyroid cartilage, about midway between the superior and inferior borders. Inferior to the thyroid cartilage is the cricoid cartilage followed by the trachea. The latter two are separated by the cricothyroid membrane. The cricoid cartilage is the only fully circumferential cartilaginous ring, whereas the remaining tracheal cartilages are C-shaped, providing anterior rigidity. The posterior membranous tracheal wall comprises the trachealis muscle. The thyroid gland sits between the cricoid cartilage and can extend down to the level of the first and second tracheal rings. Inferiorly, the brachiocephalic trunk or the innominate artery crosses superolaterally from left to right. It is important to consider the location of the great vessels when determining the appropriate location for the tracheotomy [Figure 1 for view of the laryngotracheal anatomy].

Figure 1

Laryngotracheal anatomy

EQUIPMENT

The standard hospital tracheotomy tray [Figure 2a] has a variety of instruments but the minimum equipment necessary to perform a surgical cricothyrotomy or tracheotomy is a scalpel and a cannula. The most common equipment used is shown in Figure 2b and includes a scalpel, a tracheal hook, clamp/hemostat, forceps, small retractors, tracheal dilator, and a tracheotomy tube or an endotracheal tube. In many cases, substitutions maybe made, as in using a bent 18-gauge needle instead of a tracheal hook. There are ready-made kits, whether for cricothyrotomy or percutaneous tracheotomy, which include all the needed materials for the specific technique. If time permits, one should review the contents of the kit or the equipment available prior to starting the procedure.

Figure 2

(a) Standard hospital tracheotomy tray; (b) basic equipment needed for a tracheotomy

TRACHEOTOMY

Indications

There are numerous indications for performing a tracheotomy. The oldest remains acute upper airway obstruction, but in more recent times, this surgery has been utilized in the setting of prolonged intubation, inability to extubate, maxillofacial trauma, laryngeal or neck trauma, obstructive sleep apnea, and as an adjunctive treatment in head and neck oncology whether for tumor ablation, secondary effects of radiation therapy, or reconstruction of the maxilla or mandible. Inability to extubate can be due to multiple factors related to pulmonary disease, immobility of the vocal fold, and so on.

Preparation and positioning

There are multiple ways to perform a tracheotomy and many surgeons have their own preferences and techniques. Two important conditions to check preoperatively are the coagulopathic status and ventilator settings of the patient. Patients with a high requirement of inspired oxygen and on high levels of positive end-expiratory pressure (PEEP) are at an increased risk for significant desaturation during the surgical procedure. A high concentration of oxygen will also increase the risk of airway fire if electrocautery is used.

Prior to starting the procedure, the neck is examined and the sternal notch, cricoid cartilage, and thyroid cartilage are identified and marked [Figure 3a for details on appropriate marking and positioning]. One should also note the size and thickness of the neck as well as the ability of the patient for neck extension. Appropriate positioning is crucial, especially for larger, more obese patients. The patient should be placed on a firm shoulder roll and the neck placed in extension to allow the best exposure of the laryngotracheal complex. In obese patients, the bed can be placed in the Trendelenburg position which uses gravity to allow the anterior chest wall and breast tissue to fall away from the surgical field and also help with ventilatory mechanics. The shoulders and arms can be tucked and pulled caudally. Finally, using tape to retract the chin and submental tissues superiorly can also help with exposure. Positioning in the obese short-necked patient can be the most difficult and tedious portion of the case. However, such efforts are critical and can be the determining factors in deciding whether the case is easy or difficult.

Figure 3

(a) Appropriate patient position and marking of key landmarks; (b) subtotal cervical lipectomy to improve visualization; (c) secure tracheotomy with silk stitch for Bjork flap

Technique

The incision is placed just below the cricoid cartilage at the level of the first or second tracheal ring. The incision can be horizontal or vertical depending on the preference of the surgeon. Often, a horizontal incision will be chosen for an elective procedure, and a vertical incision for an emergent procedure. Local anesthesia, typically 1% lidocaine with 1:100,000 epinephrine is infiltrated to promote hemostasis through vasoconstriction. The incision is started with a scalpel blade 15’ through the skin and dissection into the subcutaneous tissues is continued with monopolar electrocautery. Optionally, the cervical adipose tissue superficial to the strap musculature can be excised (subtotal cervical lipectomy) to improve exposure of the trachea and facilitate the replacement of an inadvertently dislodged cannula in the postoperative period [Figure 3b].

It is important to continually palpate and identify the midline. The strap muscles are identified and divided in the midline to visualize the thyroid cartilage, isthmus of the thyroid gland, and the cervical trachea. Depending on the location and the size of the thyroid gland, it can be retracted superiorly, inferiorly, or divided. In general, the surgeon will choose to divide the isthmus to acquire a better operative exposure and/or facilitate replacement of an inadvertently dislodged cannula. The thyroid isthmus can be divided by electrocautery or between clamps and ties.

Prior to entering the airway, it is critical to directly communicate with the anesthesia team to ensure a fraction of inspired oxygen (FiO2) level at or below 30%, an important fire safety precaution if the cautery is necessary to control bleeding. To prevent an inadvertent puncture of the endotracheal tube (ETT) cuff, the ETT can be advanced to position the cuff just above the carina. In this manner, the ETT is advanced caudal to the tracheal fenestration site, avoiding rupture of the cuff and maintaining the ability to ventilate and provide PEEP.

The airway plan is discussed with the scrub technician and the anesthesia team to ensure smooth execution. The tracheotomy tube of the desired size and one size smaller are made available. For difficult cases, an ETT can be inserted into the tracheal fenestration to secure the airway initially. The cuff of the tracheotomy tube is checked to ensure integrity, and the tube is prepared with the introducer in place and the inner cannula nearby. A cricoid hook is used to allow for anterior displacement of the trachea [Figure 4]. A 1-2 cm incision is made on the anterior tracheal wall between the second and third tracheal rings. A square segment of the third tracheal ring can be removed to create a fenestration, or an inferiorly based flap can be fashioned. If needed, the tracheal window can be gently dilated with a pronged tracheal spreader, avoiding any trauma to the posterior tracheal wall. If the inferiorly based flap or Bjork flap is used, a stitch is placed to secure the flap to the skin.

Figure 4

Anterior tracheal fascia with cricoid hook in place

The anesthesia team withdraws the ETT such that the tip sits above the window and the tracheotomy tube is inserted, the obturator removed, the inner cannula replaced, the cuff inflated, and the ventilator circuit connected. Proper position of the tube is confirmed by bilateral rise of the chest and return of end-tidal carbon dioxide. The tracheotomy tube is then secured in the desired manner [Figure 3c].

Complications: Early and Late

Hemorrhage is the most common early complication. In a recent multi-institutional study, the use of stay sutures was linked with decreased bleeding.[9] Any major bleeding, especially from an arterial source, may require operative exploration. Pneumothorax and/or subcutaneous emphysema are less common. Mucous plugging or obstruction due to blood clots can occur postoperatively and be managed with the use of humidified air and regular gentle suctioning. Most tracheotomy tubes used commonly have an inner cannula which can be removed and cleaned on a routine basis, thus minimizing obstruction. In the early postoperative course, inadvertent displacement of the tracheotomy tube may result in a false passage as the tract is not mature.

Most of the later complications are secondary to constant pressure/irritation applied to the surrounding tracheal mucosa. This includes formation of granulomas, tracheal stenosis, and formation of fistulas either in the esophagus or the innominate artery. Tracheo-innominate fistulas are linked to low-placed tubes and patients with excessive movement of the head. This complication has a 25% mortality rate.[10] If it does occur, manual pressure over the tract or overinflation of the cuff when it is seated in this tract can help tamponade the bleed until the patient can be taken back to the operating room for further exploration.

CRICOTHYROTOMY

Indications/Contraindications

In an emergent setting, a cricothyrotomy is recommended according to the guidelines of the American Trauma Life Support developed by the American College of Surgeons.[11] This can be performed in both a field and hospital setting by a variety of health-care professionals. This type of surgical airway is perceived to be easier to perform as it is safer theoretically, has less bleeding, and requires less surgical time.[1213] However, it is important to emphasize that a cricothyrotomy is considered a temporizing surgical airway. Cricothyrotomy should not be performed in children less than 12 years of age, as the cricothyroid membrane is quite narrow resulting in an increased risk of permanent laryngeal injury.[14] This technique should also be avoided in those with suspected laryngotracheal injury, as instrumentation at this level can exacerbate the injury.

Positioning and technique

Similar to a tracheotomy, the patient should be supine with a straight neck. The key landmarks, the thyroid and cricoid cartilage, as well as the cricothyroid membrane, should be palpated and marked if needed. These landmarks may be difficult to identify in obese patients. A vertical incision is made through the skin and further dissection is carried vertically until the cricothyroid membrane is identified. A horizontal incision is made through the cricothyroid membrane and then widened with a hemostat or two-pronged tracheal spreader. The chosen cannula is then inserted through this fenestration and placement is confirmed.

Complications and considerations

Acute complications are noted in 15% of the cases of an emergent cricothyrotomy.[15] As with a tracheotomy, there is a possibility of bleeding from the insertion site, misplaced tube, damage to surrounding neck structures, and pneumothorax. The unique complication with cricothyrotomy is an increased risk of subglottic stenosis due to superior location compared to a traditional tracheotomy. Based on this, conversion to a conventional tracheotomy tube within 72 hours of placement is recommended. Talving et al. reviewed 20 case series published on cricothyrotomy and noted an overall rate of of 2.2% of subglottic stenosis among 511 procedures; the majority of the included studies were retrospective.[16] Weymuller performed a prospective study which reported a rate of >30% of stenosis for those who underwent a cricothyrotomy after endotracheal intubation.[17]

In a retrospective chart review conducted by Dillon et al. over a six-year period at a level-one trauma center, there were 34 surgical airways, of which 10 were cricothyrotomies, whereas the remaining were emergent tracheotomies. At a military trauma hospital in Iraq, the operative logs of six otolaryngologists were reviewed noting 196 patients with airway compromise requiring either intubation or placement of a surgical airway in a 30-month period. Nine had complicated intubations, but a majority underwent emergent tracheotomies (183/196), with only three patients undergoing cricothyrotomies.[18] This study is biased in that only the case logs of head and neck surgeons were reviewed. There was no mention regarding the reason for a cricothyrotomy. The use of tracheotomy in the setting when intubation is not possible is considered to be a safe alternative.[19] These studies suggest that although cricothyrotomies are considered the surgical airway of choice in an emergent setting, emergent tracheotomies are safe and maybe more commonly performed.

NEEDLE CRICOTHYROTOMY

In an emergent setting, a needle cricothyrotomy can be performed. This procedure is meant to be temporizing, until an alternative airway can be secured. This technique is contraindicated for patients with complete upper airway obstruction, as placement of the needle into the trachea can result in increased intrathoracic pressures resulting in barotrauma such as pulmonary laceration, pneumothorax, pneumomediastinum, decreased venous return, or cardiac fibrillation.[20]

Positioning of the patient and indications are similar to those of a cricothyrotomy. The cricothyroid membrane is identified via palpation, and an 18-gauge needle with a catheter connected to a 3 cc syringe with saline is introduced into the cricothyroid membrane. Correct placement is assumed once air is aspirated. The adaptor from a 7 mm ETT is connected to the empty syringe barrel, and a ventilator circuit can then be attached to deliver oxygen or jet ventilation [Figure 5].

Figure 5

Equipment and setup for a needle cricothyrotomy

Complications

As this technique requires the use of a needle, insertion can lead to damage to the back wall of the trachea or larynx or perforation of the esophagus. Massive subcutaneous emphysema and pneumothorax may develop during ventilation if the needle is not in the correct position.

Considerations

Needle cricothyrotomy serves only as a temporary airway, as ventilation is limited to the diameter of the needle catheter. It allows for oxygenation for 15-20 minutes, but conversion to a formal cricothyrotomy or tracheotomy is required immediately.

PERCUTANEOUS TRACHEOTOMY

History

Percutaneous tracheotomy, although seemingly recent, was first described by Sanctorio Sanctorius in 1626. It was described in further detail by Laurentius Heister as a “fast method of tracheotomy that could be done with little pain”. A French physician, Bauchot, is accredited with performing the first percutaneous tracheotomy.[21] The term itself was coined by Shelden et al. in 1955.[22] There are multiple techniques available such as the Ciaglia Blue Rhino technique, Schachner's Rapitrach method, or the PercuTwist introduced by Frova and Quintel.[23]

Endoscopic visualization is critical to performing a percutaneous tracheotomy safely. This is usually performed on an intubated patient and a bronchoscope is passed through the ETT, the ETT withdrawn so that the cuff is within the glottis, and the bronchoscope used to monitor the entire procedure. The Seldinger technique, or dilation and insertion over a guide wire, is used for most percutaneous tracheotomy procedures. An introducer needle is inserted into the midline anterior tracheal wall between the first and second or second and third tracheal rings. A guide wire is inserted through the needle introducer into the tracheal lumen. A stab incision generous enough to allow passage of the desired cannula is made through the skin to expand the site of the cutaneous puncture. Tapered dilators are inserted over the guide wire to create a passage through the subcutaneous tissues and dilate the tracheal fenestration. The tracheotomy tube is then inserted using a special introducer designed to pass over the guide wire. The guide wire and introducer are removed, leaving the tracheotomy tube in place.[24] The Ciaglia Blue Rhino technique allows for a single-step dilation of the stoma, theoretically decreasing the risk of injury to the posterior tracheal wall. The Rapitrach technique employs a dilating forceps device that has a beveled metal cone-shaped tip. This is inserted by applying pressure and advancing over a wire into the trachea. The PercuTwist offers a single-step dilation with a self-tapping screw to get controlled rotating dilation of the airway.[23]

The indications for a percutaneous tracheotomy are the same for a routine tracheotomy. There are no absolute contraindications to this procedure although pediatric age, a thick short neck, distorted anatomy of the neck, coagulopathy, and a high-riding innominate artery are relative contraindications.

The rate of complications is operator dependent and decreases with experience. Initial studies noted significant morbidity and mortality with this technique, but a more recent study by van Heurn et al. noted tracheal narrowing in 26% of the cases, but the stenoses were noted to be operator dependent. There were 14 deaths, but none were related to the tracheotomy.[21] Wang et al. noted the potential for false passage, specifically due to a calcified tracheal cartilage. The blind passage of dilators can result in trauma to the side and posterior tracheal walls and cause increased bleeding.[24] Considering the complications that are at an increased risk with the percutaneous tracheotomy technique, patients with long thin necks, non-calcified tracheal rings, and easily palpable landmarks are considered to be ideal candidates.

Advantages

One of the main advantages of this technique over a traditional open tracheotomy is that this procedure can be performed at the bedside avoiding many expenses related to the operating room setting, requiring fewer personnel, and using lesser equipment. There are further costs that are avoided in waiting time for undergoing a surgical tracheotomy in the operating room, as many require a longer duration of stay in the intensive care unit. Other potential advantages include lesser tissue dissection and injury to the surrounding tissue, smaller scar, and tighter fit of the tracheotomy tube.[25] A more secure fit would theoretically result in less bleeding as the surrounding vasculature is compressed. In a prospective randomized study, the percutaneous method was noted to be quicker and simpler, but there were more late tracheal complications noted.[26]

MANAGEMENT

Regardless of the type of tracheotomy performed and the technique used, follow-up is crucial. This is particularly true for tracheotomies or cricothyrotomies performed in an emergent setting. There is always the potential for both early- and late-term complications. In any person who has previously undergone a surgical airway, one should exercise extreme care if another surgical airway is needed, as the much of the expected anatomy of the neck and the fascial planes are distorted, making dissection and identification of landmarks more difficult. Preoperative counseling regarding these potential risks is important.

The decision to proceed with decannulation of any surgical airway should be well thought out. In many cases, proper evaluation of the airway either intraoperatively or in a clinical setting with fiberoptic examination is necessary to ensure that there are no abnormalities that would preclude decannulation. Generally a capping trial is conducted for 24 hours to ensure that the patient can adequately maintain his/her oxygen saturation. Once this is successfully completed, the tracheotomy tube is removed and an occlusive dressing is applied. Patients are encouraged to apply pressure over the stoma when talking/coughing to help facilitate full closure.

CONCLUSION

A surgical airway can be approached in many different ways. One should be familiar with anterior neck anatomy and with different surgical techniques to help minimize complications. In any setting when a patient cannot be ventilated or oxygenated, one should not hesitate to proceed with the placement of a surgical airway. In such emergencies, any attempt to secure the airway is lifesaving and necessary.