title: Laryngeal mask airway or endotracheal tube for percutaneous dilatational tracheostomy: a comparison of visibility of intratracheal structures.
abstract: OBJECTIVE
  Some severe complications during percutaneous dilatational tracheostomy (PDT) may be related to poor visualization of tracheal structures. Subjectively, the bronchoscopical view obtained via a laryngeal mask airway (LMA) seems to be better than that obtained with an endotracheal tube (ETT). In this prospective, randomized study, we compared LMA and ETT as the ventilatory device during PDT mainly with respect to visualization of tracheal structures. The quality of ventilation and airway-related complications are also reported.
  
  
  METHODS
  In this prospective, randomized study, PDT was performed using an LMA (n = 33) or an ETT (n = 30). Quality of ventilation and visualization of tracheal structures (thyroid, cricoid, and tracheal cartilages) were rated as follows: very good (1), good (2), difficult (3), and not possible (4) with LMA/ETT. A rating of 4 required the alternate airway. Groups were compared using the chi(2) test.
  
  
  RESULTS
  Visualization of tracheal structures was better with the LMA: ratings were 1 or 2 in 94% of patients with an LMA, compared with 66% of patients with an ETT (P <0.05). Visual control during puncturing the trachea was 1 or 2 in 97% of patients using an LMA and 77% of patients for an ETT (P < 0.05). A rating of 4 was assigned to 1 patient with an LMA and to 3 patients with an ETT. Hemodynamic variables were similar in both groups. Blood gas analysis during PDT showed decreased Pao(2) in both groups, and increased Paco(2), which was more pronounced with an ETT compared with an LMA (59 +/- 14 mm Hg and 51 +/- 11 mm Hg [P < 0.05]). In the ETT group, 2 patients were extubated accidentally, and in another patient, the bronchoscope was damaged because of insufficient visualization of the tracheal puncture site.
  
  
  CONCLUSIONS
  The LMA technique showed definite advantages regarding visualization of relevant tracheal structures and the dilation process compared with an ETT. This may be especially relevant in the hands of inexperienced intensivists and in cases of difficult patient anatomy where improved structural visualization optimizes operating conditions.
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Diako Hospital, Flensburg, Academic Teaching Hospital of the University of Kiel, Germany. linstedtul@diako.de
authors.forename: Ulf
authors.initials: U
authors.lastname: Linstedt
authors.forename: Michael
authors.initials: M
authors.lastname: Zenz
authors.forename: Kirsten
authors.initials: K
authors.lastname: Krull
authors.forename: Dietrich
authors.initials: D
authors.lastname: Häger
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Prengel
mesh_terms: D000368:Aged; D001784:Blood Gas Analysis; D004106:Dilatation; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects; D017214:Laryngeal Masks / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D015656:Respiratory Mechanics / Q000502:physiology; D014132:Trachea / Q000033:anatomy & histology*; D014139:Tracheostomy / Q000379:methods*