We aimed to demonstrate the feasibility of a modified percutaneous dilatational tracheostomy (PDT) procedure using a newly designed endotracheal tube EZ (easy) tracheostomy (the EZT).
The EZT is designed with 3 main goals in mind—(i) to allow a single operator to safely perform PDT at the bedside while providing continuous bronchoscopic guidance, (ii) to ensure uninterrupted mechanical ventilation during most of the PDT procedure via a secure airway, and (iii) to significantly minimize the complications associated with the current PDT procedure.
PDT is a common bedside procedure for critically ill intensive care unit (ICU) patients. It is a safe and cost-effective alternative to surgical tracheostomy,1–3 with a success rate >97%.4,5 Since the introduction of bronchoscopic guidance for this procedure,6 the incidence of major complications—pneumothorax, pneumomediastinum, false passage of tracheostomy tube, and posterior wall laceration with fistula formation—have decreased to <2%.5,7
However, the introduction of the bronchoscope into the endotracheal tube (ET tube) for PDT has led to many other complications such as hypoxia, hypercarbia, auto-positive end-expiratory pressure (PEEP), loss of airway, increased intra-cranial pressure, and needle damage to the bronchoscope.8–15 In addition, continuous bronchoscopic guidance requires 2 experienced physicians if it is to be performed safely.
The shortage of trained operators and the high incidence of medical ICU patients on high PEEP/FiO2 (relative contraindications) limit the use of bedside PDT. Many patients undergo surgical tracheostomy at higher costs and risks related to transportation and anesthesia.
The EZT is designed with an aim to substantially reduce the common problems associated with the bedside PDT procedure, to widen its application to sicker patients, and make it possible for a single trained operator to perform the procedure under continuous bronchoscopic visualization.
The EZT (Figs. 1, 2) is a double-lumen ET tube consisting of a viewing tube and a ventilation tube. The viewing tube has an inner diameter (I.D.) of 3.5 mm to accommodate a pediatric bronchoscope. It is shorter in length and slides over the anterior wall of the ventilation tube. The ventilation tube has an I.D. of 7 mm and connects to the ventilator. It is longer in length and can be adjusted to extend from 2 to 14 cm beyond the distal tip of the viewing tube. A distal balloon lies at the very distal end of the ventilation tube. This distal balloon has the same volume and pressure of a conventional ET tube balloon but has an asymmetric design extending more anteriorly than posteriorly. When the distal balloon is inflated, it pushes the ventilation tube toward the posterior tracheal wall and creates more space anteriorly. The EZT also has a large volume proximal balloon (85 cm3) extending to 1 cm above the distal tip of the viewing tube. The balloon remains above the vocal cords and is designed (along with the distal balloon) to hold the EZT in place once the optimal positioning is achieved. The EZT also comes with a suction catheter of 3 mm diameter and sufficient length. This can be passed into the viewing tube to clear secretions from the trachea.
CORRECT PLACEMENT OF THE EZT (FIGS. 2, 4)
The EZT replaces the patient’s current ET tube by exchange over a tube exchanger. Once in place, the distal balloon is inflated, the EZT’s position in the trachea is quickly confirmed, and the ventilator is connected to the ventilation tube. A pediatric bronchoscope is inserted into the viewing tube and the distal tip of the viewing tube is placed just below the vocal cords in the anterior-midline position (Fig. 3). The proximal balloon is then inflated fixing the viewing tube in position. Now the distal balloon is deflated and the ventilation tube is adjusted so that its distal tip lies just above the carina. The distal balloon is then reinflated—pushing the ventilation tube toward the posterior tracheal wall and fixing the EZT in position. The space that is created anterior to the ventilation tube—extending from the vocal cords above to the distal balloon below—is used to perform the PDT.
The adult human trachea is 10 to 14 cm in length. An adult male trachea measures 19.5±2.3 mm in the coronal plane and 20.3±2.2 mm in the sagittal plane. An adult female trachea measures 16.6±2 mm in the coronal plane and 16.8±2.2 mm in the sagittal plane.16,17 With the 7 mm I.D. ventilation tube occupying the posterior portion of the trachea and the distal balloon extending 2 cm above the carina, the anterior space created for the PDT procedure can measure from 7.1 mm deep and 7 cm long in a small woman to 15 mm deep and 11 cm long in a large man. Considering the distensible nature of the human trachea and the compressibility of the ventilation tube, this space is adequate.
THE MODIFIED PDT TECHNIQUE INCORPORATING THE EZT (FIGS. 3, 4)
The procedure starts with a quick ultrasound examination of the patient’s neck and identification of anatomic landmarks. The EZT is then placed in an optimal position as described above. The operator then lays the bronchoscope at the patient’s bedside, scrubs in, and prepares the tracheostomy tray and the tracheostomy site. With continuous bronchoscopic guidance provided by the pediatric bronchoscope, the operator identifies the correct entry site by the palpation method. The operator then inserts the needle, followed by the guide wire, the straight and the curved dilator in the normal sequence. An appropriately sized tracheostomy tube is then placed on a dilator of matching size and passed over the guide wire until its tip is at the tracheal wall. At this time, the operator deflates the distal balloon for the first time during the procedure. While holding the viewing tube in place, the ventilation tube is withdrawn until its distal tip lies proximal to the point of entry of the guide wire (this step can also be performed by a respiratory therapist). The bronchoscope continues to provide continuous visualization and can guide immediate reintubation if needed. The operator then wears new sterile gloves and inserts the tracheostomy tube. The bronchoscope is now withdrawn from the viewing tube and inserted into the tracheostomy tube to confirm correct placement before the EZT is removed.
PERFORMANCE OF EZT ON A CADAVER AND A MANNEQUIN MODEL
Our purpose was to establish the feasibility of our technique in a cadaver and a mannequin model. We manufactured 2 EZT prototypes using ET tubes 3.5 and 7 mm in size and a combitube. We achieved EZT models very close to the one we describe here. The models were initially tested on our intubation training mannequin and a step-wise procedure for modified PDT (described above) was established. We were then provided with a fresh-frozen cadaver of a 74-year-old man with average weight and height to test our technique using the EZT. A low-resolution clarus pocket scope with a laryngoscope handle as the light source was used instead of a pediatric bronchoscope. The pocket scope has no working channel and cannot be maneuvered, but with the correct placement of the viewing tube and the use of the 3 mm diameter suction catheter as described above, these properties were not needed. The procedures were visualized using a camera placed onto the eye piece of the pocket scope and attached to a TV monitor.
The modified PDT procedure was first performed on the cadaver by an experienced intensivist (>100 PDTs). Five procedures were performed using the spaces from above the first tracheal ring to below the fourth tracheal ring in the midline. A pulmonary and critical care fellow with limited experience (<20 PDTs) then performed 5 PDTs in the same spaces but using the right lateral tracheal wall.
Each PDT procedure was completed by a single operator without assistance. The procedure started with direct laryngoscopy tracheal intubation of the cadaver using a regular ET tube of 7.5 I.D. This was followed by exchange with an EZT using a tube exchanger. The EZT’s position inside the trachea was established by bronchoscopy. The operator then positioned the EZT in the optimal position. After fixing the EZT in place, the bronchoscope was placed at the bedside. The trachea was then vigorously manipulated (as one would to establish entry site by the palpation method) and the EZT was observed for displacement from optimal positioning. The operator then scrubbed and performed the PDT using the EZT protocol described above (with the exception of mechanical ventilation). After each procedure, the pocket scope was used to assess correct placement of the tracheostomy tube in the intended position for that attempt.
All procedures were successfully completed on the first attempt. All airway exchanges were successful, with no loss of airway. Optimal visualization and EZT positioning was achieved in all cases. There was no loss of visualization, optimal positioning, or airway during any procedure. There was no needle damage to the posterior tracheal wall, ET tube balloon, or bronchoscope. The positioning of the viewing tube just below the vocal cords in the anterior midline position made it possible to correctly identify the intended entry site in every attempt. The distal balloon was deflated for no more than 15 seconds before tracheostomy tube insertion. The operators found the modified PDT procedure to be very easy to perform compared with conventional PDT.
The PDT procedure, as currently performed, is associated with many complications such as hypoxia, hypercarbia, auto-PEEP, minor posterior wall lacerations, and increased intra-cranial pressure.8–15
These complications seem commonplace and yet are difficult to quantify from the literature. There are many reasons for this18: (i) most studies report only major complications. For example, studies describing endoscopically guided PDT did not report desaturation as an independent complication before 2005,7 (ii) many studies in the past have used PDT procedures fundamentally different from the single tapered dilator (Blue Rhino, introduced in 2000) technique popular today, (iii) the complication rates and the definitions of complications have varied widely between studies, and (iv) bronchoscopic guidance (arguably the factor adding to minor complications while preventing major ones) was not used until 1989. Evidence that inadequate ventilation and loss of airway control during PDT is a substantial problem comes indirectly from the frequent attempts to introduce new safer ways of performing the procedure. For example: (i) using a 4-mm uncuffed ET tube for ventilation with a bronchoscope placed alongside the ET tube for visualization,19 (ii) using laryngeal mask airways,20 (iii) placing tube exchangers into the airway alongside the bronchoscope,21 (iv) changing ET tubes smaller than 7 mm with larger size tubes,7 and (v) using pediatric bronchoscopes in the presence of pulmonary pathology.7 Further evidence comes from the 2 largest single-center studies4,22 evaluating percutaneous tracheostomy. In both studies, operators used direct laryngoscopy to position the patient’s ET tube with the balloon just below the vocal cords. The investigators acknowledged that the use of a bronchoscope for ET tube positioning can lead to loss of airway. In the second study,22 the bronchoscope was first introduced into the trachea only after the guide wire had been placed to quickly confirm correct placement. The reason given is that the presence of the bronchoscope in the ET tube significantly impairs ventilation. The study stated that in patients with ET tube size ≤7 mm I.D., effective mechanical ventilation was impossible with the bronchoscope in place. This practice led to significant tracheostomy tube malpositioning in 4 cases. Of note, when a similar technique was applied in a medical-surgical ICU, posterior wall perforations were seen in 12.5% of the cases.23 To facilitate proper placement and continuous endoscopic visualization, the investigators22 advocate changing the ET tube to a larger size or using pediatric scopes.
There is also the issue of increasing demand for PDT while having shortage of trained operators.
Considering the above factors, the EZT seems to have significant potential. This needs to be proven in a well-designed clinical trial.
The EZT might make it possible for single operators to safely perform PDT while also providing continuous bronchoscopic guidance. It has the potential to significantly decrease loss of airway, incorrect tracheostomy placement, needle damage to the bronchoscope, posterior wall puncture, and inadequate ventilation or oxygenation related to the current PDT procedure. In addition, if a PDT procedure is interrupted, canceled, or delayed, the EZT could be safely left in place and used as a regular ET tube. Additionally, in patients who present with respiratory failure with a high likelihood for tracheostomy in the near future (example extubation failure, trauma, severe lung disease), the EZT could be used for the initial intubation. The viewing tube could then be used for continuous subglottic suction using the 3-mm suction catheter.
In contrast, there are potential disadvantages: (i) the modified percutaneous tracheostomy procedure using the EZT begins with a tube exchange. This has possible complications and should be performed carefully. But in all the studies in which the patients had their ET tubes exchanged—for larger size tubes, laryngeal mask airways, or pediatric tubes4,7,19,20,22—loss or airway was not stated to be a problem. Also, it is possible to design a variant of the EZT with just a viewing tube. This tube would slide over the patient’s existing ET tube and, after optimal positioning, it would be possible to secure it in place with a locking mechanism. This would eliminate the need for any airway exchange. (ii) There are concerns that the pediatric bronchoscope may be ineffective in clearing secretions. Many studies have used pediatric bronchoscopes in appropriate patients without many problems.4,7,22 Also, our cadaver had copious secretions that were easily removed when the specially designed suction catheter was passed through the viewing tube. The 2 balloons ensure that once cleaned, the operating field remains clear of secretions for the rest of the procedure.
The drawbacks also need to be established on the basis of further clinical studies.
It is feasible for a single operator to perform PDT with continuous bronchoscopic guidance when using the EZT on a human cadaver. Clinical studies are warranted to evaluate this new tool.
1. Freeman BD, Isabella K, Lin N, et al. A metaanalysis of prospective trials comparing percutaneous and surgical tracheostomy in critically ill patients. Chest. 2000;118:1412–1418
2. Delany A, Bagshaw SM, Nalos M. Percutaneous dilatational tracheostomy
versus surgical tracheostomy in critically ill patients: a systematic review and meta-analysis. Crit Care. 2006;10:R55
3. Higgins KM, Punthakee X. Meta-analysis comparison of open versus percutaneous tracheostomy. Laryngoscope. 2007;117:447–454
4. Dempsey GA, Grant CA, Jones TM. Percutaneous tracheostomy: a 6 year prospective evaluation of the single tapered dilator technique. Br J Anaesth. 2010;5:782–788 Epub 2010 Sep 2
5. Fikkers DG, Briedé IS, Verwiel JM, et al. Percutaneous tracheostomy with blue rhino technique. Anaesthesia. 2002;57:1094–1097
6. Paul A, Marelli D, Chiu RC, et al. Percutaneous endoscopic tracheostomy. Ann Thorac Surg. 1989;47:314–315
7. Kost KM. Endoscopic percutaneous dilatational tracheotomy. Laryngoscope. 2005;115:1–30
8. Imami E, Hogan SL, Komer K, et al. Percutaneous dilatational tracheostomy
. Crit Care Med. 1994;22:A67
9. Polderman KH, Spijkstra JJ, de Bree R, et al. Percutaneous dilatational tracheostomy
in the ICU: optimal organization, low complication rates, and description of a new complication. Chest. 2003;123:1595–1602
10. Dongelmans DA, van der Lely AJ, Tepaske R, et al. Complications of percutaneous dilating tracheostomy. Crit Care. 2004;8:397–398
11. Durbin CG Jr. Early complications of tracheostomy. Respir Care. 2005;50:511–515
12. Blankenship DR, Kulbersh BD, Gourin CG, et al. High-risk tracheostomy: exploring the limits of percutaneous tracheostomy. Laryngoscope. 2005;115:987–989
13. Reilly PM, Sing RF, Giberson FA, et al. Hypercarbia during tracheostomy: a comparison of percutaneous endoscopic, percutaneous Doppler, and standard surgical tracheostomy. Intensive Care Med. 1997;23:859–886
14. Seder DB, Lee K, Rahman C, et al. Safety and feasibility of percutaneous tracheostomy performed by neurointensivists. Neurocrit Care. 2009;10:264–268
15. Beiderlinden M, Walz KM, Sander A, et al. Complications of bronchoscopically guided percutaneous dilational tracheostomy. Intensive Care Med. 2002;28:59–62
16. Mehta S, Myat HM. The cross-sectional shape and circumference of the human trachea. Ann R Coll Surg. 1984;66:356–358
17. Breatnach E, Abbott GC, Fraser RG. Dimensions of the normal human trachea. Am J Roentgenol. 1984;142:903–906
18. Powell DM, Price PD, Forrest LA. Review of percutaneous tracheostomy. Laryngoscope. 1998;108:170–177
19. Ferraro F, Capasso A, Troise E, et al. Assessment of ventilation during performance of elective endoscopic guided percutaneous tracheostomy. Chest. 2004;126:159–164
20. Tarpey JJ, Lynch L, Hart S. The use of the laryngeal mask airway to facilitate the insertion of a percutaneous tracheostomy. Intensive Care Med. 1994;20:448–449
21. Deblieux P, Wadell C, McClarity Z, et al. Facilitation of percutaneous dilational tracheostomy by use of a perforated endotracheal tube exchange. Chest. 1995;108:572–574
22. Kornblith Burlew CC, Moore EE, et al. One thousand bedside percutaneous tracheostomies in the SICU. J Am Coll Surg. 2, 2011;212:163–170
23. Trottier SJ, Hazard PB, Sakabu SA, et al. Posterior tracheal wall perforation during percutaneous dilational tracheostomy. Chest. 1999;115:1383–1389