31.4.1 Describe the Anatomy of the Airway with Respect to Performing a Percutaneous Dilational Tracheotomy
Surgical access to the airway through the trachea requires knowledge and recognition of surface anatomy landmarks of the larynx as well as the important adjacent structures in the neck. Most importantly, dexterity and familiarity with flexible bronchoscopy is essential as a guide to safely complete a PDT.
Easily palpable landmarks in the anterior neck include the following: the hyoid is situated high in the neck, just below the submental space, and provides a primary suspensory role for the airway; the thyroid notch, most prominent in adult males, identifies the superior aspect of the thyroid cartilage; the cricoid cartilage is the only complete ring and is bridged by the cricothyroid membrane to the inferior portion of the thyroid cartilage (Figure 31-1). With the neck extended, palpation inferiorly from the cricoid cartilage may reveal proximal tracheal rings and the thyroid gland. The vocal cords are protected by the body of the thyroid cartilage anteriorly and attach to the arytenoid cartilages which articulate from the posterosuperior margin of the cricoid ring.
Surgical airway anatomy. (A) Thyroid cartilage. (B) Cricothyroid membrane. (C) Cricoid cartilage. Provided with permission from Walts et al (ref. 14).
An experienced practitioner must perform flexible bronchoscopy to identify the level of important internal laryngeal structures (supraglottis, glottis, and subglottis) and to transilluminate the area between the second to fourth tracheal rings. In patients with poorly palpable surface anatomy, transillumination and visual confirmation of the guide needle will ensure proper positioning of the tracheostomy tube.
31.4.2 Compare and Contrast the Different Sites at Which Surgical Airway Access Can Be Performed
Surgical access to the airway can be gained at the cricothyroid space, subcricoid space, or between any of the tracheal rings. To secure an emergency airway rapidly, a cricothyrotomy is preferable because the cricothyroid membrane is superficial, easily identifiable, and thus easiest to access (see Chapter 13).3 Controversy has existed about the long-term use of cricothyrotomy due to early reports of subglottic stenosis, limiting its use to emergency airway access.11 However, reexploration of this notion in a recent prospective study involving 118 patients has shown the incidence and severity of complications to be similar between traditional tracheotomy and cricothyrotomy techniques.11
The first modern-day surgical tracheotomy (ST) performed by Chevalier Jackson in the early 1900s involved entering the trachea at the second or third tracheal ring.12 He advocated avoiding the first and second tracheal rings due to a high incidence of subsequent subglottic stenosis.13 Current consensus dictates that in ideal circumstances a tracheotomy is performed between tracheal rings two to four. Injury to the first ring or cricoid cartilage may increase the risk of subglottic stenosis, whereas placement too low may predispose to erosion of the anterior tracheal wall and possible creation of a tracheoinnominate fistula.14
The first percutaneous tracheotomy not requiring neck dissection was described in 1955 by Shelden,15 during which a slotted needle was introduced blindly into the tracheal lumen. Several deaths occurred secondary to laceration of vital structures in proximity to the airway.16 Toye and Weinstein17 performed the first tracheotomy using a Seldinger technique where a single, tapered dilator was introduced with a recessed cutting blade. In 1985, Ciaglia18 introduced a dilational Seldinger technique which has since been refined and has now become one of the most popular techniques for PDT.19 Initially, PDT was performed in the immediate subcricoid space,18 but in a follow-up publication the space between the first and second tracheal rings was advocated.20 But, the more distal approach (beyond the second ring) was not recommended due to the risk of bleeding from the thyroid isthmus20 or from puncture of an aberrant, high-riding innominate artery.
31.4.3 Describe the Different Techniques Used to Perform an Elective Surgical Airway (for Techniques to Manage an Emergency Surgical Airway, Refer to Chapter 13)
126.96.36.199 Surgical Tracheotomy
ST is usually performed under general anesthesia in the operating room. The neck is extended to elevate the trachea into the neck (Figure 31-1). Depending on the length of the patient's neck, a horizontal incision is generally made crossing the midline approximately 2 cm above the sternal notch. The subcutaneous tissue and platysma muscle are divided transversely. The remainder of the dissection is performed longitudinally through the superficial cervical fascia and the linea alba dividing the strap muscles. Lateral retraction of the strap muscles often reveals the thyroid isthmus, which is commonly divided to provide better surgical access and to minimize the risk of bleeding by its manipulation.14 Various types of tracheal incisions have been used. Quite frequently a superiorly based Bjork flap or window is made by unroofing the second or third tracheal ring.
To avoid damaging the indwelling ETT cuff during tracheotomy, it is a common practice to deflate the cuff and purposely advance the ETT distally into the right mainstem bronchus prior to making an incision in the trachea. Following tracheal access, the ETT is withdrawn under direct vision to just above the tracheotomy site by the airway practitioner. Superior retraction on the cephalad tracheal ring with a tracheal hook and spreading of the tracheal incision facilitates subsequent insertion of the tracheostomy tube.
Endotracheal positioning is confirmed by connecting the tracheostomy tube to the ventilatory circuit and monitoring for the presence of end-tidal CO2. These final measures, in addition to assessing lung compliance and airway pressures, are ascertained prior to the complete removal of the ETT. The tracheostomy tube is then secured with sutures, and a tie passed around the neck.14
188.8.131.52 Percutaneous Dilational Tracheotomy
The PDT technique is easily performed at the bedside with two operators: one performing the tracheotomy while the second provides ventilation and oxygenation. It is essential to continuously monitor vital signs including pulse oximetry, blood pressure, heart rate, and rhythm. The patient should be ventilated with 100% oxygen throughout the procedure. The patient's current sedative regime can be supplemented with an opioid and an intravenous sedative/hypnotic such as a benzodiazepine or propofol.21 It is important to maintain immobility during insertion of the needle to prevent inadvertent puncture of the posterior tracheal wall or coughing during the insertion of the tracheotomy tube, for example, through the use of a nondepolarizing muscle relaxant, such as rocuronium. For continued mechanical ventilation during the procedure, the cuff of the ETT is deflated and adjustments to tidal volume, respiratory rate, and PEEP are made to compensate for the air leak. At our institution, the patient is manually ventilated with a bag-mask device and 100% oxygen throughout.
Flexible bronchoscopy through the ETT to facilitate PDT insertion was introduced in 1989.22 Bronchoscopy allows visualization of the needle entering the trachea, helping to confirm its location in the midline at the correct tracheal interspace, as well as ensuring that the ETT is not punctured or impaled and minimizing the risk of damaging the posterior tracheal wall.19 In the case of accidental premature extubation, the bronchoscope can also be used to guide ETT reinsertion. There may also be a role for videoscopic bronchoscopy during teaching as there is a learning curve to performing PDT.16 The disadvantages of flexible bronchoscopy include difficulties with ventilation and oxygenation leading to hypercarbia and hypoxia19 and the potential for damage to the bronchoscope by the needle or guidewire.
Adjuncts, such as ultrasound and capnography, are increasingly being used to aid successful PDT. Ultrasound can help to determine the site of tracheal puncture prior to PDT, identifying structures at risk of hemorrhage such as variant arterial anatomy, primarily an aberrant innominate artery.23 Kollig et al used ultrasound to determine the site of puncture followed by bronchoscopy; ultrasound findings changed the tracheal puncture site in 24% of the procedures.24 Portable monitors are now available to quantify CO2 at the bedside. Capnography and bronchoscopy have been shown to be equally effective to confirm tracheal needle placement.25
Prior to tracheal puncture, the ETT must be withdrawn to avoid cuff laceration or ETT impalement. Besides bronchoscopy, alternative methods have been advocated to confirm adequate ETT withdrawal before tracheal puncture. These include use of direct laryngoscopy with a tube exchanger, ETT cuff palpation, and premeasured blind withdrawal.19 In 2000, our group described a technique using the Trachlight™ (Laerdal Medical Inc., Wappingers Fall, NY), a common and inexpensive intubation device, as an alternative to bronchoscopy to facilitate the PDT. With the internal stiff wire removed from the Trachlight™, the pliable lightwand device is advanced into the ETT. In order to place the lightbulb of the Trachlight™ at the tip of the ETT, the number markings on the Trachlight™ wand shaft must be lined up with those on the ETT. Anterior neck transillumination26 can then be used to confirm adequate withdrawal of the ETT prior to the needle puncture.
Since the original report of PDT by Ciaglia, the procedure has undergone three modifications. These include the movement of the tracheal cannulation site to one or two interspaces caudal to the cricoid cartilage; the use of bronchoscopy and the use of a single, bevelled dilator instead of multiple dilators.19 While currently several kits are available for the Ciaglia single dilator technique, only the Ciaglia Blue Rhino™ kit (Cook Critical Care, Bloomington, IN) will be presented.
Under optimal conditions, the neck is extended and the surgical field is aseptically prepared (Figure 31-2A). The tracheostomy tube cuff must be checked for leaks and then well lubricated. The first or second tracheal interspace is located and local anesthetic injected (Figure 31-2B). A vertical skin incision is made in the midline from the level of the cricoid cartilage downward 1 to 1.5 cm. The wound is dissected bluntly to the subcutaneous fascia using a hemostat. The ETT should be withdrawn to 1 cm above the anticipated needle insertion site under bronchoscopic guidance. A 17-gauge sheathed introducer needle is advanced in a midline, posterior, and caudad direction. The tracheal air column is identified when air is aspirated into a fluid-filled syringe (eg, 2-3 mL of lidocaine) (Figure 31-2C). At this time the ETT is advanced and withdrawn 1 cm to verify that the needle does not concomitantly move, to rule out inadvertent impalement of the ETT. The outer sheath is then advanced into the trachea while the introducer needle is removed. The fluid-filled syringe is then reattached to the sheath and its position in the trachea is reconfirmed by free flow of air. To minimize the responses to the subsequent insertion of the dilator, the lidocaine in the syringe is instilled into the trachea. The syringe is removed and a 1.32 mm diameter J-tipped guide wire is advanced through the sheath into the trachea (Figure 31-2D). The sheath is then removed. Although not specified by the manufacturer, in our experience, it is beneficial to make a second cut around the guide wire with the scalpel to provide room for the dilator. A short 14 French introducing mini-dilator is advanced over the guide wire using a slight twisting motion and then removed. The Ciaglia Blue Rhino™ dilator, after soaking in water, is then advanced over the guide wire while maintaining the wire position (Figure 31-2E). The dilator and guide wire are advanced together into the trachea up to the black skin level mark. The dilator is withdrawn and advanced several times to help create the stoma, whereupon it is removed. The lubricated tracheostomy tube with its internal dilator is then inserted over the guide wire and advanced as a unit until it reaches the flange (Figure 31-2F and G). The guide wire and dilator are then removed, leaving the tracheostomy tube in situ (Figure 31-2H). The cuff is inflated and the tracheostomy tube's proximal connector is attached to the ventilator (Figure 31-2I). Once insertion into the trachea has been confirmed by end-tidal CO2 detection, the translaryngeal ETT is removed.
Percutaneous dilational tracheotomy. (A) Monitors are applied and the neck is extended and prepped. (B) The first or second tracheal interspace is identified. (C) An introducer needle is inserted with a syringe and aspirated until a free flow of air is obtained. (D) A J-tipped guide wire is guided into the trachea through the needle. (E) A dilator is advanced over the guide wire. (F and G) The tracheostomy tube is then inserted over the dilator and guide wire, and the tracheostomy tube and dilator are advanced as a unit into the trachea. (H) The dilator is then removed leaving the tracheostomy tube in situ. (I) The cuff of the tracheostomy tube is inflated and connected to the ventilator.
Fig 31-2F provided with permission from Cook Critical Care, Bloomington, IN.
Other PDT techniques have been developed.7,19 The Rapitrach kit (Surgitech Medical, Sydney, Australia) used a dilating tracheotome with blades designed to slide over the guidewire into the trachea. To create a stoma, it was necessary to squeeze the blades open.27 Unfortunately, the Rapitrach method resulted in a high rate of posterior tracheal wall and balloon cuff tears and was removed from the US market.19 The Griggs technique uses a Howard-Kelly forceps that is introduced into the tracheal lumen with the guidewire.28 A stoma is created when the forceps are opened, similar to the Rapitrach method, but without a cutting blade. This technique is popular in South America and Europe.19 A third method is a translaryngeal approach developed by Fantoni and Ripamonti.29 With this technique, a guide wire is inserted retrograde into the tracheal space and pulled out through the mouth. A trocar and tracheostomy tube with a pointed tip is then advanced over the wire and with traction applied to the guidewire, the trochar-tracheotosmy tube assembly is advanced through the mouth into the trachea. A pretracheal incision is then made over the skin so that the trocar end of the tracheostomy tube can be pulled through the anterior neck. The trocar is then cut away leaving the tracheostomy tube in place. This technique avoids the downward direction of dilation and thus may minimize damage to the posterior tracheal wall.19 A fourth method uses a single dilator from the Percutwist™ Tracheostomy Dilator Set (Rüsch, Kernen, Germany). This procedure uses a Seldinger technique in which a hydrophilically coated Percutwist™ dilator is moistened and advanced over a guide wire with a twisting motion to enlarge an opening in the anterior tracheal wall. A 9.0 mm ID tracheostomy tube is fitted with the insertion dilator and subsequently advanced over the guidewire into the trachea.30 The Percutwist™ has had a higher rate of posterior wall puncture than the Ciaglia Blue Rhine technique.31
31.4.4 Describe and Compare Different Tracheostomy Tubes. Which Tube Would You Choose for This Patient?
In selecting a tracheostomy tube, patient anatomy and ventilatory needs must be considered. These needs will influence choice of tube internal diameter, length, cuff design, use of an inner cannula, and presence or absence of fenestrations. Sizing usually refers to the inner diameter (ID). The smallest outer diameter that satisfies the requirement for ventilation should be chosen.14 Optimal sizing should aim for a tracheostomy tube approximately three-quarters of the diameter of the tracheal lumen.
In our case presentation, the indication for tracheotomy is prolonged intubation and ventilation, so a cuffed tube which seals the airway and prevents loss of tidal volume would be a good selection. One example of such a cannula is the No. 6 (6.0 mm ID) Shiley (Mallinckrodt, St. Louis, MO) with a large-volume, low-pressure, air-filled cuff14 (Figure 31-3B). It is important to maintain an inflated cuff pressure of less than 30 cm H2O to prevent tracheal mucosal ischemia and minimize the risk of erosion. Once the patient is weaned from the ventilator, conversion to a fenestrated tube (Figure 31-3C) might be appropriate because it reduces resistance to flow of air through the lumen of the tube, enabling vocalization.14 Another option is to downsize the nonfenestrated tracheostomy tube which would also permit the patient to vocalize, while minimizing the risk of granulation tissue formation at the site of the fenestration. Excessive granulation tissue can cause tracheostomy tube obstruction and may also produce impressive bleeding from the airway. But, in general, the choice of a tracheostomy tube is often based on the practitioner's individual experience and preference.
Tracheostomy tubes. (A) Bivona Foam-Cuf silicone tube (Bivona Medical Technologies, Gary, IN). (B) Shiley-cuffed nonfenestrated tube. (C) Shiley-cuffed fenestrated tube. (D) Shiley-uncuffed fenestrated tube (Shiley Mallinckrodt, St. Louis, MO).
Special consideration must be given to the obese patient. Standard tracheostomy tubes are unlikely to conform to the anatomy and thus a better choice is a flexible tube which is extra long and adjustable,14 such as Bivona (Bivona Medical Technologies, Gary, IN) or Tracoe (TRACOE Medical GmbH, Frankfurt, Germany) tracheostomy tubes. The disadvantage of these tubes is that they have a single lumen without an inner cannula. They do have an advantage of minimizing risks of an inappropriately fitted tube, such as tube obstruction if too short, or necrosis of the anterior tracheal wall if too long.
31.4.5 What Are the Advantages of Performing Percutaneous Dilational Tracheotomy over Surgical Tracheotomy?
In general, the complications of PDT are few and are comparable to ST.32 Theoretical advantages of PDT include a smaller skin incision, less dissection, and tissue trauma which may lead to less hemorrhage, fewer infections, fewer tracheal problems, and fewer cosmetic deformities. In addition, the procedure can be performed at the bedside in the ICU, by nonsurgical personnel, decreasing the risk of patient transport to the operating room with less overall cost and less use of human resources.13,20,33 The disadvantages of performing PDT in the ICU relate mainly to lack of proper facilities and equipment. Poor lighting conditions and a crowded environment can also be hazardous. These risks can be minimized by proper preparation of a surgical set that includes drapes, tracheostomy tubes of various sizes, portable electrocautery, and a surgical lamp. A difficult airway cart should also be immediately available with appropriate anesthetic drugs, including muscle relaxants.