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Acta Clin Croat 2012; 51:505-510

Conference Paper

Management of the difficult airway Vesna Novak-Jankovič Clinical Department of Anesthesiology and Intensive Therapy, University Medical Centre Ljubljana, Ljubljana, Slovenia SUMMARY – Management of difficult airway is one of the most challenging tasks for anesthesiologists, and failure of securing it could have fatal consequences. We must be prepared to deal with problems in management of difficult airway at any time. Difficult intubation can either be anticipated or unanticipated. An anesthesiologist must be aware of the possibility of both situations to arise and preparations must be taken to deal with such cases and improve the safety of our patients. Practice guidelines are systematically developed recommendations that help anesthesiologists in the management of difficult airway. Key words: Difficult airway, management, unanticipated, anticipated

Introduction The failure to maintain a patient airway is a source of serious concern for anesthesiologists. A difficult airway is defined as the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with face mask ventilation and/or difficulty with tracheal intubation1. Difficult mask ventilation is defined as the inability of a trained anesthesiologist to maintain oxygen saturation >90%, using a face mask, 100% oxygen and positive pressure ventilation. Difficult intubation is defined as the need for more than three attempts for intubation of the trachea or more than 10 minutes to achieve it. The incidence of difficult mask ventilation is estimated to be 0.9%-5%, and the incidence of difficult intubation is 0.13%-13%2-7. The major complications associated with the difficult airway include death, hypoxic brain injury, cardiopulmonary arrest, unnecessary tracheotomy, airway Correspondence to: Prof. Vesna Novak-Jankovič, MD, PhD, Clinical Department of Anesthesiology and Intensive Therapy, University Medical Centre Ljubljana, Zaloška 7, 1000 Ljubljana, Slovenia E-mail: [email protected] Received July 9, 2012, accepted August 23, 2012

Acta Clin Croat, Vol. 51, No. 3, 2012

trauma including aspiration of gastric contents, and damage of soft tissues and teeth. In order to avoid this fatal outcome, several societies have developed guidelines for management of the difficult airway8-11. Prediction of Difficult Airway Management Medical history and physical examination are important tools in prediction of the difficult airway. An airway physical examination should be performed prior to the initiation of anesthetic care in all patients. Focused medical history (previous anesthesia record or anesthesia document) may detect medical, surgical and anesthetic factors that may indicate the presence of a difficult airway1. Patients with congenital syndromes (Pierre-Robin, Treacher-Collins, KlippelFeil, etc.) and acquired diseases (acromegaly, ankylosing spondylitis, tumors, burns, hematoma, cervicofacial injuries, Madelung’s disease, etc.) are associated with the presence of a difficult airway12. An airway physical examination should be performed before anesthetic management to detect physical characteristics that may indicate the presence of a difficult airway (Table 1). 505

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Management of the difficult airway

Table 1. Components of the preoperative airway physical examination Airway examination component Face inspection Patency of nares Teeth Relation of maxillary and mandibular incisors during normal jaw closure Relation of maxillary and mandibular incisors during voluntary protrusion of lower jaw Temporomandibular joint movement Visibility of uvula Shape of palate Compliance of mandibular space Shape of neck Voice Scars Range of motion of head and neck Assessment of submandibular space Assessment of body habitus



Class I

Findings that give cause for concern Beard, size of nose, mouth and tongue, jaw protrusion, jewelry Masses inside nasal cavity, deviated nasal septum Relatively long upper incisors or canines, protruding teeth, lack of teeth, an edentulous state Maxillary incisors anterior to mandibular incisors Inability to protrude the lower jaw and mandibular incisors beyond the upper incisors Interincisor distance less than 3 cm Not visible Highly arched or very narrow Stiff, indurated, occupied by mass Thick and short (sternomental distance below 12 cm) Presence of hoarse voice or stridor Presence of signs of previous tracheostomy Patient cannot touch tip of chin to chest or cannot extend neck more than 35° Hypomental distance less than 3 cm Thyromental distance less than three ordinary finger breadths less than 6.5 cm Pregnancy, obesity, snoring

Class II

Class III

Class IV

Fig. 1. Classification according to the modified Mallampati test. Class I: visualization of the soft palate, fauces, uvula, anterior and posterior pillars. Class II: visualization of the soft palate, fauces and uvula. Class III: visualization of the soft palate and base of uvula. Class IV: visualization of only hard palate.

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Management of the difficult airway

Specific Screening Test to Predict Difficult Intubation There are a number of specific clinical assessments that have been developed to try to identify patients



Grade 1

Grade 2

who will prove difficult to intubate: Mallampati test (Fig. 1), thyromental distance (normal ≥6.5 cm), sternomental distance (normal ≥12.5 cm), protrusion of the mandible, and radiographic assessment13-15.

Grade 3

Grade 4

Fig. 2. Classification according to Cormack and Lehane during direct laryngoscopy. Grade 1: visualization of the entire laryngeal aperture. Grade 2: visualization of the posterior commissure of the laryngeal aperture only. Grade 3: visualization of the epiglottis only. Grade 4: visualization of the soft palate only.

Direct laryngoscopy visualization of the larynx according to Cormack and Lehane is illustrated in Figure 216. Preparation for Anticipated Difficult Airway Appropriate equipment must be immediately available on the portable storage unit (Fig. 3). This will include laryngoscopes with a selection of blades, a variety of endotracheal tubes, stylets, flexible bougies, oral and nasal airways, a cricothyroid puncture kit, reliable suction equipment, supraglottic ventilatory devices, video laryngoscopes, rigid optic laryngoscopes, and flexible fiberoptic bronchoscopes. Awake intubation under local anesthesia may be performed using fiberoptic flexible bronchoscope. Retrograde intubation is a technique for patients with cancrum oris. Management of Unanticipated Difficult Airway

Fig. 3. Portable storage unit for difficult airway management at University Medical Centre Ljubljana. Acta Clin Croat, Vol. 51, No. 3, 2012

The British Difficult Airway Society (DAS) has developed very simple algorithms that use only a few airway devices which are available in many settings17-19. Our national guidelines are adopted and modified DAS guidelines (Fig. 4). The anesthesiologist should inform the patient on the airway difficulty and notification cards which we use at University Medical Centre Ljubljana are very useful (Fig. 5). 507

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Direct laryngoscopy

Management of the difficult airway

Any problems

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Plan A: Routine endotracheal intubation Direct laryngoscopy – check: proper position of the head laryngoscopic technique and vector external laryngeal manipulation opening vocal cords If poor view: use the flexible introducer, change of blade, video laryngoscopes, AirTraq Failed intubation Plan B: ILMA or LMA – up to 2 insertions Oxygenation and ventilation ↓ Plan C: Failed oxygenation: SpO2