Percutaneous dilatational tracheostomy (PDT) is one of the most commonly performed ICU procedures. For clinicians performing PDT, knowledge of the pertinent anatomy, the ideal population for PDT, techniques of the percutaneous method, potential complications, and postprocedural tracheostomy care are crucial to assure excellent patient care. As this book is directed to the EM intensivist, this chapter will focus on PDT for the nonsurgeon.
Within the specialty of critical care and the field of medicine as a whole, there is an ever-growing body of literature to support or refute treatment modalities, procedures, and management decisions. In the evaluation of any literature, knowing the limitations, evaluating the methodology, and understanding the difficulty of performing prospective studies must be taken into account before being too dogmatic about an approach to a clinical issue of procedural or managerial significance.
The airway is divided into the upper and lower airways. The upper airway consists of the nasopharynx, oropharynx, and laryngopharynx. The lower airway begins at the vocal cords and consists of the larynx (which includes the cricoid cartilage [the only complete cartilaginous ring in the trachea] and cricoid membrane) and the elements of the tracheobronchial tree. The adult trachea is 12 cm in length and the external diameter of the trachea in the coronal plane is 2.3 cm.1 The trachea has a series of 20 “U”-shaped cartilaginous rings; each tracheal ring is 4 mm wide and separated by a 2-mm membranous segment.2 The female trachea is smaller in diameter and length. The general shape of the trachea is ovoid with posterior flattening; yet as one ages, the trachea becomes narrower and deeper (laterally narrower and deeper anterior–posteriorly). The trachea is approximately 18–32 mm deep from the skin, and the posterior wall of the trachea is 40–56 mm deep from skin.3
On bronchoscopic evaluation of the trachea, the cartilaginous rings are seen anteriorly and the longitudinal folds of dense elastic fibers are present posteriorly. Distally, the carina can be seen branching into the right and left main bronchi.
Paramount to performing PDT is the assessment of externally pertinent anatomy (Figures 49-1 and 49-2). Identifying the patient with a short neck, assessing the landmarks in the obese patient, and evaluating potential vascular contraindications must be completed prior to deciding on PDT. In addition, issues of previous tracheal surgery and cervical spine injury are important anatomic considerations.
The skin incision is made in the midline, beginning below the cricoid cartilage and extending down toward the suprasternal notch. An incision made with these landmarks will lie over the second to fourth tracheal rings. (Reproduced with permission from Reichman EF, Simon RR. Emergency Medicine Procedures. New York, NY: McGraw-Hill Inc; 2004. Figure 15-9.)