Verso le Linee Guida SIAARTI per il controllo delle vie aeree in area critica e in emergenza intraospedaliera: il ruolo dell’endoscopia e strumentario
Petrini F. (1), Frova G.
(1) Anestesia, Rianimazione e Terapia del Dolore P.O.Clinicizzato SS.Annunziata- ASL Chieti
Università G.D’Annunzio, Chieti-Pescara
Literature reports that almost 30% of anaesthesia-related critical incidents occur as a consequence of airway management difficulty (1, 2).
Difficult airways may be considered as an important epidemiological problem: it is really difficult to assess the real dimension of the problem, for several reasons. The lack of common definitions, the large differences occurring in the different surgical Specialties or in the different clinical settings (elective and emergency, in-hospital and out-of-hospital), the difficulty to locate a “difficult airway event” in a statistical model and the practical problems of randomized controlled trials in this field of investigation make it really difficult to obtain precise numbers, and represent a great challenge for epidemiologists.
Furthermore we must not forget the importance of subjective experience and the matter of “near-accidents” (especially whenever a problem is overstepped, so that it comes forgotten) or, even worse, a certain reluctance to report accidents.
According to recent data incidence of difficult mask ventilation is ranging from less than 0,03% up to 5 % according to the definition used (3). Similarly difficult intubation occurs between 1 and 20 cases over 100 patients, while difficult laryngoscopy occurs from 1 to 8% in North America (4,5), from 1 to 4,9% in the UK (6,7) 6,8% in Asia (8), 10.4% in Italian data (9) and 7,6% in a Greek study (10).
Failed intubation or procedure abandon is less frequent than difficult intubation ranging from 0,05% (31) to 0,5% (11). The actual situation should account on larger numbers, according to the anaesthesist tendency to an early withdrawal in case of non emergency failed intubations and thanking to the availability of a large number of extraglottic devices whenever intubation is not mandatory.
The incidence of more severe clinical scenarios as the can’t intubate can’t ventilate patient (CICV) is probably very low for OR (elective anaesthesiological situations) but not for emergency department: the CICV scenario and the failed intubation leading to cricothyrotomy occur in 0,56% of difficult airway management situation in emergency wards, and are much more rare in elective situations (12,13).
The choice of a careful strategy of difficult airway prediction is the best way to afford the problem If on one hand there is the problem of definitions and incidence, in fact, on the other it is possible to affirm that at least 70% of difficult airways problems may be predictable and anticipated, thus avoided, even if we must not forget that prediction is not a error-proof science.
About 90% of difficult intubations may be revealed with preoperatory evaluation (high sensibility), but only half of them result in a real difficulty and thus in a correct prediction (low specificity), and in any case a certain percentage, ranging from 0.65 to 8% remains unpredicted or unpredictable (14-17)
All the recently published Guidelines, from the 1993 ASA Guidelines (19) and reviewed in 2003 to the National Airways Societies documents (20,21), up to the 1998 SIAARTI Guidelines (22) recently reviewed (23), suggest important strategies for predicted or unexpected difficult airway management. The most important concept emerging is that in case of (severe) predicted difficulty or whenever a patient with unexpected severe difficulty may be delayed and awakened, a key role for patient’s safety and for procedure’s success is played by fiberoptic intubation. In the following sections the role of fibrescope and of new fiberoptic-like alternative devices will be briefly discussed.
The role of fibrescope (FOB) in all difficult airway management algorithms is clear and standardized: British Guidelines for diagnostic flexible broncoscopy (24) clearly introduced some important rules for fiberoptic devices uses and management and recently ASA underline the role of FOB in trauma patients (19). No valid alternatives to FOB may be considered in a patient whose mouth opening is limited, or in which several previous intubation attempts have failed: the choice of awake FOB intubation secures airways and allows the maximum safety for the patient. In experienced hands and in presence of adequate ventilation devices and solutions (dedicated face masks, dedicated trumpets and airways) also FOB intubation in anaesthetized patient represents a safe technique, even if in some cases a more prudential awake intubation allows larger safety conditions. FOB is an extremely important device for airways management in ICU, and also represents the gold standard for tube position confirmation in cases of difficult intubation, and in pediatric difficult airway management, especially in young children or newborns, FOB intubation alone or in combination with LMA for ventilation and pathway establishment, is the most safe and successful solution (25)
For all these reasons in the recent SIAARTI Recommendations its availability wherever anaesthesia is performed is considered mandatory (23).
On the other hand FOB may have some important well known limitations and pitfalls (26): there are optical problems due to secretions and temperature (27), patient’s compliance and airway topicalization play a key role for awake FOB intubation success, while serious difficulties may be encountered during anaesthetized patient FOB intubation. Even expert FOB users may encounter the pitfall of “hang on” phenomenon, with severe difficulty in tracheal tube advancing because of arytenoids impingement (28), while some dedicated tube should limit this phenomenon (29).
In this setting dangerous situation of undiagnosed tube misplacement or ventilation difficulties may be encountered, such as Langeron and Coworkers suggest in a recently published paper comparing FOB and Intubating LMA (30). Last but not least FOB represent an interesting example of teaching difficulty in the field of Anaesthesia: a constant feedback and a certain skill development and maintenance are considered necessary for a correct and safe FOB use (31,32). Finally, if FOB represents the best choice for anticipated difficulty, where a detailed planning of all available strategies and possible complications is possible, it is absolutely contraindicated in emergency situations, neither in skilled hands.
Glidescope (TM) and videolaryngoscopes
Glidescope is a videolaryngoscope (33) with a peculiarly shaped blade and an integrated video system which allows optimal view of glottic opening with high intubation success rates using a semirigid stylet. There is a growing number of papers in Literature suggesting an important role for this device both for teaching and for difficult airways management. It provides good glottic view if compared with conventional laryngoscopy (34-36), and future developments seem to be very promising both for awake intubation (37) or as an aid for difficult FOB intubation (38). In expert hands, Glidescope may represent a valid alternative in emergency situation before patient’s awakening or if surgery is mandatory. Other videolaryngoscopes actually allow an external view of what happens at the blade’s tip, without significant improvements of glottic view like Glidescope does.
Bonfils Laryngoscope (TM) and other rigid devices
Bonfils laryngoscope is a rigid fiberoptic device designed to perform oral intubation made up with a thin straight cylindrical body with a 40 degree curve a few centimeters from its distal end (39). Preliminary data seem to show interesting results, with an acceptably low traumatism and faster than ILMA in a recent comparison paper (40,41). Similarly WU-Scope (TM) a tubular fiberoptic laryngoscope, seems to have interesting features and future developments. (42,43). The pitfall for these devices may be represented by the skill necessity and by the risk of soft tissues or tracheal lesions because of devices’ rigidity.
Intubating fiberoptic stylets
Optical stylets, which incorporate flexible fibreoptic imaging elements in an intubation stylet, have become available in the last decade. More than 10 new optical stylet devices have been introduced since 1995, showing that combining viewing capability with the familiar handling of a stylet is an appealing concept. Liem and Coworkers provided a complete review on this topic (44), in which there is still an important lack of published papers support.
C-Trach represents a recent evolution of Intubating LMA designed by A. Brain in 1998. It provides the view of the glottic opening by adding to the classic ILMA an integrated video system with a built-in 3.5” display, a light source and a modified epiglottis elevator bar (TM). No studies are actually available, except for some abstracts (45), but promising development may come from this device, that, independently on the possibility of obtaining a good glottic view, intubation possibility and, over all, ventilation possibility are almost always granted. This may represent ai important help for emergency situations and out-of-operatory room setting or in unanticipated difficult intubation in which FOB is contraindicated.
Continuous and rapid technologic development provides a larger number of devices for difficult airways management, with fascinating possibilities in terms of airways structures vision. Anaesthesia and Intensive Care is a field in which, often, only seeing is believing; anyway we must never forget that eyes see what mind knows.
1) Caplan RA, Poster KL, Ward RJ, Cheney FW. Adverse respiratory events in anesthesia: a closed claims analysis. Anesthesiology 1990; 72: 828-33
2) A. R. Aitkenhead Injuries associated with anaesthesia. A global perspective. Br. J. Anaesth. 2005 95: 95-109
3) Langeron O, Masso E, Huraux C, et al. Prediction of difficult mask ventilation. Anesthesiology 2000; 92:1229-36
4) Benumof JL. Management of the difficult adult airway. Anesthesiology 1991; 75: 1087-1110
5) Crosby ET, Cooper RM, Douglas MJ et al. The unanticipated difficult airway with recommendations for management. Can J Anesth 1998; 45: 757-776
6) Samsoon GLT, Young JRB. Difficult tracheal intubation: a retrospective study. Anaesthesia, 1987; 42: 487-490
7) Savva D. Prediction of difficult tracheal intubation.Br J Anaesth 1994; 73:149-53
8) Koay CK. Difficult tracheal intubation – analysis and management in 37 cases. Singapore Med J 1998; 39:112-4.
9) Restelli L, Moretti MP, Todaro C, Banfi L. The Mallampati’s scale: a study of reliability in clinical practice. Minerva Anestesiol 1993; 59: 261-5
10) Voyagis GS, Kyriakis KP, Roussaki-Danou K, Bastounis EA. Evaluating the difficult airway. An epidemiological study. Minerva Anestesiol 1995; 61: 483-9
11) Benumof JL. Management of the difficult adult airway. Anesthesiology 1991; 75: 1087-1110
12) Bair AE, Filbin MR, Kulkarni RG, Walls RM. The failed intubation attempt in the emergency department: analysis of prevalence, rescue techniques, and personnel. J Emerg Med 2002;23:131-40
13) David T. Wong, Kevin Lai, Frances F. Chung, and Ranee Y. Ho Cannot Intubate-Cannot Ventilate and Difficult Intubation Strategies: Results of a Canadian National Survey. Anesth Analg 2005;100 1439-1446
14) Iohom G, Ronayne M, Cunningham AJ. Prediction of difficult tracheal intubation. Eur J Anaesthesiol 2003; 20: 31-6.
15) Eberhart LHJ, Arndt C, Cierpka T, et al. The Reliability and Validity of the Upper Lip Bite Test Compared with the Mallampati Classification to Predict Difficult Laryngoscopy: An External Prospective Evaluation. Anesth Analg 2005;101 284-289
16) Merah NA, Wong DT, Foulkes-Crabbe DJ, Kushimo TO, Bode CO. Modified Mallampati test, thyromental distance and inter-incisor gap are the best predictors of difficult laryngoscopy in West Africans. Can J Anesth 2005;52 291-296
17) Crosby E. The unanticipated difficult airway – evolving strategies for successful salvage. Can J Anesth 2005;52 562-567
18) Burle CM, Walsh MT, Harrison BA, Curry T, Rose SH. Airway management after failure to intubate by direct laryngoscopy:outcomes in a large teaching hospital. Can J Anesth 2005;52 634-640
19) Wilson WC. Trauma:AirwayManagement. ASA Difficult Airway Algorithm Modified for Trauma and Five Common Trauma Intubation Scenarios. ASA Newsletter, November 2005, Volume 69(Number 11); 2005
20) Crosby ET, Cooper RM, Douglas MJ et al. The unanticipated difficult airway with recommendations for management. Can J Anesth 1998; 45: 757-776
21) Boisson-Bertrand et al. SFAR. Difficult intubation: a collective expertise. Ann Fr Anesth Reanim 1996; 15: 207-14
22) Frova G (coordinator). SIAARTI Guidelines. Difficult intubation and management of difficult airways. Minerva Anestesiologica 1998; 64: 361-71.
23) SIAARTI Task Force, Recommendations for airway control and difficult airway management, Minerva Anestesiologica 2005;71:617-657 (www.siaarti.org)
24) British Thoracic Society Bronchoscopy Guidelines Committee. British Thoracic Society guidelines on diagnostic flexible bronchoscopy. Thorax 2001;56:(suppl I)
25) M. Johr, TM. Berger. Fiberoptic intubation through the laryngeal mask airway (LMA) as a standardized procedure. Paediatric Anaesthesia 2004; 14: 614-615
26) Ovassapian A, Yelich SJ, Dykes HM. Fibreoptic nasotracheal intubation: incidence and causes of failure. Anesth Analg 1983; 62: 692
27) Durga VK, Millns JP, Smith JE Maneuvers used to clear the airway during fiberoptic intubation. British J Anesth 2001; 87:201–11
28) Wheeler M, Dsida RM. Fiberoptic intubation: Troubles with the “tube.” Anesthesiology 2003; 99:1236–7
29) Hwan S.Joo,Viren N.Naik,and Georges L.Savoldelli. Parker Flex-TipTM are not superior to polyvinylchloride tracheal tubes for awake fibreoptic intubations. Can J Anesth 2005;52 297-301
30) O Langeron, F Semjen, JL Bourgain, A Marsac, AM Cros. Comparison of the Intubating Laryngeal Mask Airway with the Fiberoptic Intubation in Anticipated Difficult Airway Management. Anesthesiology 2001; 94:968–72
31) J. E. Smith and A. P. F. Jackson. Learning fibreoptic endoscopy Nasotracheal or orotracheal intubations first? Anaesthesia, 2000, 55, pages 1072-1075
32) Marsland CP, Robinson BJ, Chitty CH, Guy BJ. Acquisition and maintenance of endoscopic skills: Developing an endoscopic dexterity training system for anesthesiologists. J Clin Anesth 2002; 14:615–9
33) Cooper RM. Use of a new videolaryngoscope (GlideScope) in the management of a difficult airway. Can J Anaesth2003 Jun-Jul;50(6):611-3
34) Rai MR, Dering A, Verghese C. The GlideScope system: a clinical assessment of performance. Anaesthesia 2005; 60: 60–4.
35) Sorbello M, Zingale SF, Giunta F, Paratore A, Ventura L, Micali C, Cutuli M, Gelsomino M, Frova G, Petrini F, Mangiameli S. Impact of Glidescope vs conventional MacIntosh laringoscopy on Cormack-Lehane (cl) grading with head in neutral position. Abstract presented at Airways 2005, Abano Terme 23-25 june 2005, p 18
36) T. J. Lim, Y. Lim and E. H. C. Liu. Evaluation of ease of intubation with the GlideScope or Macintosh laryngoscope by anaesthetists in simulated easy and difficult laryngoscopy. Anaesthesia, 2005, 60:180–183
37) Doyle DJ. Awake intubation using the GlideScope video laryngoscope: initial experience in four cases. Canadian Journal of Anesthesia 2004; 51: 520–1.
38) Doyle DJ. GlideScope-assisted fiberoptic intubation: a new airway teaching method. Anesthesiology 2004; 101: 1252.
39) M. Halligan and P. Charters A clinical evaluation of the Bonfils Intubation Fibrescope. Anaesthesia, 2003, 58, pages 1087–1091
40) B. Bein, M. Yan,P. H. Tonner,J. Scholz, M. Steinfath and V. Dorges. Tracheal intubation using the Bonfils intubation fibrescope after failed direct laryngoscopy. Anaesthesia, 2004, 59: 1207–1209
41) B. Bein, F. Worthmann, J. Scholz, F. Brinkmann, P. H. Tonner, M. Steinfath, V. Dorges. A comparison of the intubating laryngeal mask airway and the Bonfils intubation fibrescope in patients with predicted difficult airways. Anaesthesia, 2004, 59, pages 668–674
42) Andrews SR, Mabey MF. Tubular fiberoptic laryngoscope (WuScope) and lingual tonsil airway obstruction. Anesthesiology 2000; 93:904-5
43) Sprung J, Weingarten T, Dilger J. The use of WuScope fiberoptic laryngoscopy for tracheal intubation in complex clinical situations. Anesthesiology 2003; 98:263-5
44) EB Liem, DG Bjoraker, D Gravenstein New options for airway management: intubating fiberoptic stylets. British J Anaesth 91 (3): 408-18 (2003)
45) Sorbello M, zingale SF, Giunta F, Paratore A, Ventura L, Laudani A, Fontana E, Cutuli M, Frova G, Petrini F, Mangiameli S. Preliminary evaluation of C-Trach: a perspective study on 30 patients. Abstract presented at Airways 2005, Abano Terme 23-25 june 2005, p 17