EUROPEAN JOURNAL OF EMERGENCY MEDICINE, 2002,9,298^302

EXTENDED ABSTRACTS FROM INVITED SPEAKERS AT THE 1ST MEDITERRANEAN CONGRESS ON EMERGENCY MEDICINE, STRESA, 2–5 SEPTEMBER 2001 Advanced prehospital techniques

A.R. THIERBACH

Department of Anaesthesiology, Johannes Gutenberg-University, Mainz, Germany

Keywords: airway management intubation; endotracheal intubation; flexible fibre optic combitube; oesophageal tracheal; laryngeal mask airways; algorithm; emergency airway

INTRODUCTION patient before every non-emergency endotracheal intubation. Approximately 2–3% of patients have Complications related to airway management in the anatomical features that make prehospital setting are frequent and, because of the difficult. Table 2 lists those findings that suggest that importance and vulnerability of the ventilatory endotracheal intubation may be difficult. system, can be life threatening within a very short time. Therefore, airway management is perhaps the Time priorities key component in the treatment of any patient in a critical condition. The urgency of airway management is divided into four categories, as outlined in Table 3. EVALUATION TECHNIQUES Perhaps most importantly of all, the emergency care provider must be able to recognize those patients in Airway management involves far more than just whom airway management may be difficult and be proficiency with tracheal intubation techniques. able to formulate and implement alternative plans in Clearly there are several techniques available and various situations. the method chosen will depend on the availability of equipment, the level of training and expertise, and the Patients who have suffered major trauma or life- patient’s specific injury or disease. threatening diseases can present the most complex airway management problems, especially in the Standard monitoring should be employed, includ- prehospital setting. Because the treatment is time- ing electrocardiography, non-invasive automated critical, evaluation is usually incomplete at the time blood pressure monitoring, pulse oximetry and airway management is undertaken. .

Trauma Alternative techniques include mask ventilation to ensure immediate oxygenation, the oesophageal Direct airway trauma may involve actual damage to tracheal Combitube and various laryngeal mask the airway or any kind of injury to nearby structures airways. Modifications of laryngoscopic blades (e.g. that distorts the anatomy of the airway. Indirect or Henderson, McCoy) and fibreoptic intubation tech- associated airway trauma affecting airway manage- niques (e.g. Bonfils, Bullard) may offer alternatives to ment will be considered to be those injuries that limit the expert even in the prehospital environment. The or influence the techniques available for airway needle or surgical cricothyrotomy is rarely required, management. Table 1 lists the injuries that may cause but remains the ‘ultima ratio’ in airway problems direct or indirect airway trauma. when all other techniques fail.

Difficult anatomy Orotracheal intubation

A comprehensive physical examination of the dental Endotracheal intubation represents the most common system and airway should be performed in each technique for securing the airway and provides the

& 2002 Lippincott Williams & Wilkins. ADVANCED PREHOSPITAL AIRWAY MANAGEMENT TECHNIQUES 299

Table 1. Direct and indirect trauma to the airways Table 4. General indications for endotracheal intubation Direct airway trauma (optimized ventilation and oxygenation) Mandibular fractures Respiratory insufficiency of any reason (e.g. high spinal Maxillary fractures cord injuries, drug overdose) Penetrating wounds (e.g. gun shot, stab injury) of neck or Multi-traumatized patients and patients in shock face Glasgow coma score o8 Indirect airway trauma Risk of aspiration (e.g. protection against gastric contents or Cervical spine injury blood) Bleeding into soft tissues of neck or face Provision of surgical anaesthesia Air emphysema and oedema of soft tissues of neck or face Pneumothorax Burns of neck and upper chest Table 5. Benefits of endotracheal intubation Protection against aspiration Provision of a route to administer drugs even without intravenous access (e.g. adrenaline, lignocaine, atropine, naloxone) Table 2. Findings that suggest a difficult intubation using Application of facilitated assisted or controlled mechanical standard direct laryngoscopy ventilation and positive end expiratory pressure Allows endotracheal suctioning and bronchial toilet Small mouth, inability to open mouth, temporomandibular joint abnormalities Narrow receding mandible Protuberant maxilla (overbite) When performing orotracheal intubation in patients Large tongue or one whose mobility is limited Less than 6 cm distance between mandible and thyroid with potential injury of the cervical spine, manipula- prominence tions of the cervical spine must be minimized, and an Inability to place the head in the ‘sniffing’ position, e.g. assistant should always apply manual axial in-line cervical spine trauma stabilization (MIAS), being careful to leave the neck in Short, full or bull neck, or the presence of a neck mass a neutral position. Immobilization of the cervical spine may also be accomplished by using other techniques such as a rigid collar or head rolls and tape. Table 3. Relative time priorities of airway management MIAS should always be combined with cricoid 1. Immediate intervention in apnoeic patients pressure applied after the patient loses consciousness. 2. Emergency intervention in patients with respiratory By placing the thumb and index finger on the cricoid distress cartilage and exerting pressure in an anteroposterior 3. Urgent intervention in patients currently stable but with direction, the oesophagus is occluded. Proponents of increased risk of aspiration due to bleeding after the ‘bimanual technique’ have the assistant place one maxillofacial trauma, or airway swelling due to smoke inhalation and airway burns hand behind the patient’s neck, flexing it into the 4. Delayed intervention in all other patients with a high risk ‘sniffing’ position, while applying conventional cri- of developing pulmonary problems such as adult coid pressure with the other hand. respiratory distress syndrome Cricoid pressure to prevent regurgitation and aspira- tion is maintained until proper placement of the most secure protection against aspiration of foreign endotracheal tube is confirmed (by visualizing the material. It is indicated in a variety of acute medical tube passing through the glottis) and the endotracheal conditions as well as trauma (Table 4). Securing of the tube cuff has been inflated. Prematurely releasing the airway with an endotracheal tube and inflated cuff cricoid pressure prior to confirming the correct offers several benefits for the treatment of patients in a placement of the tracheal tube is a common error, critical condition, as listed in Table 5. and places the patient at huge risk of aspiration if accidental oesophageal intubation has occurred. Cri- In patients with an immediate need for ventilation coid pressure must be released immediately should and to secure the airway, there are few contraindica- active vomiting occur, otherwise there is danger of tions to careful orotracheal intubation. In some oesophageal rupture. situations orotracheal intubation is relatively contra- indicated or not easy to carry out, such as in patients The duration of attempts to intubate the patient’s with massive facial trauma and laryngeal or tracheal without interposed ventilation via a mask injuries. should not exceed 30–45 s. Experience has shown that

EUROPEAN JOURNAL OF EMERGENCY MEDICINE (2002) 9(3) 300 THIERBACH patients die of hypoxia during extended unsuccessful thread on the endotracheal tube once the FFB is attempts to intubate, who could have been ventilated positioned in the trachea because of the acute angle and oxygenated via mask. formed between the oropharynx and the trachea. Retraction of the tongue and anterior displacement of Visualization of the endotracheal tube entering the the mandible can usually overcome this problem. larynx, auscultation of the chest for breath sounds and Nasotracheal intubation is often easier to perform of the epigastrium for absence of air entry into the with the FFB because the natural curve of the stomach, and observation of chest motion during nasopharynx guides the tube into the larynx. ventilation are common methods of ascertaining proper endotracheal tube placement. Detection of Fibreoptic intubating laryngoscopes expired carbon dioxide provides the most reliable evidence of tracheal rather than oesophageal intuba- Fibreoptic modifications of the laryngoscope such as tion. the Bonfils or the Bullard not only improve the view of the larynx, especially in patients with difficult Flexible fibreoptic intubation anatomy, but also permit tracheal intubation with less head and cervical spine extension than are required Although the experienced endoscopist makes the for conventional laryngoscopy. Success with these procedure appear simple, flexible fibreoptic intuba- devices, however, requires experience and proficiency tion (FFI) requires skill and practice. This technique with the emergency airway. requires more time than conventional direct laryngo- scopy, even when performed by an expert. For these Oesophageal tracheal Combitube (ETC) reasons, and the fact that the equipment is rarely available in true emergencies outside the operating The ETC is a double-lumen tube that is introduced room or the intensive care unit, this technique has blindly into the mouth that combines the functions of only a limited value for urgent situations requiring an oesophageal obturator airway and a conventional the immediate establishment of an airway. A remark- endotracheal airway. It is manufactured in two sizes: able improvement in terms of the versatility for the Combitube 37 F SA (=small adult) and the emergency use of FFI techniques is achieved by the Combitube 41 F. use of a fibrescope with a battery-driven light source in its handle. The device is designed to ventilate the lungs whether the distal end enters the oesophagus or the trachea. Topical anaesthesia is often preferable to general The longer channel has an open distal end and the anaesthesia, particularly in the patient with a pre- other channel has a blind end with multiple small carious airway. The disadvantages of general anaes- openings at supraglottic level. There is a small- thesia include relaxation of the tongue and volume distal cuff and a large-volume proximal cuff pharyngeal tissues, which may make the technique designed to obliterate the hypopharynx. If the long more difficult, and the time limitations imposed if the tube enters the oesophagus (as it does in the majority patient is apnoeic. When general anaesthesia is of cases), the patient is ventilated through the small chosen, use of an endoscopic mask with a port openings above the level of the glottis. The tidal through which the flexible fibreoptic bronchoscope volume is directed towards the glottis, and is (FFB) is passed permits uninterrupted anaesthesia prevented from passing elsewhere by the inflated and ventilation during the procedure. The largest FFB distal and hypopharyngeal cuffs. If the tube enters the that will fit easily into the endotracheal tube should be trachea, ventilation is performed via the open distal used, since visualization is improved and it is more channel. difficult to thread a large endotracheal tube over a small FFB. The ETC has been used successfully as an artificial airway during cardiorespiratory arrest. The device Adequate topical anaesthesia of the lower airway, has also been evaluated for use by intensive care unit which greatly facilitates successful FFB, is not contra- nurses and by paramedics in the prehospital setting. indicated in patients with full stomachs. Rather, The ETC is an effective substitute for tracheal caution must be taken with administering heavy intubation in cases where there is a lack of expertise sedation as it potentially creates conditions that could or familiarity with endotracheal intubation, or there is result in aspiration from reflux. an inability to intubate caused by difficult anatomy or when patients are trapped in unusual positions. Orotracheal FFB intubation permits use of a larger endotracheal tube and is associated with less tissue A disadvantage of the ETC is that suctioning of the trauma and bleeding. However, it may be difficult to trachea is impossible if it is in the oesophageal

EUROPEAN JOURNAL OF EMERGENCY MEDICINE (2002) 9(3) ADVANCED PREHOSPITAL AIRWAY MANAGEMENT TECHNIQUES 301 position. Complications of the device include lacera- tions of the pharynx and hypopharynx, oesophageal Surgical airway or tracheal perforation, and the inability to provide adequate ventilation. The Combitube is contraindi- Cricothyrotomy. Rarely, surgical cricothyrotomy may cated in the following circumstances: patients smaller be necessary. In the event that endotracheal intubation than 4 ft tall, patients with intact gag reflexes or the use of an ETC or LMA are not possible, the irrespective of their level of consciousness, patients most rapid way to secure an airway is by emergency with known oesophageal pathology, patients who cricothyrotomy. Common indications for this pro- have ingested caustic substances, and patients with cedure are foreign body obstruction, facial or laryn- obstruction of the upper airways, such as foreign gotracheal trauma, inhalation thermal injury or bodies or tumours. caustic injury of the upper airway, angioneurotic oedema, upper airway haemorrhage or epiglottitis.

Although cricothyrotomy is an excellent method of Laryngeal mask airways securing an airway rapidly, it risks significant blood loss and damage to the cricoid cartilage, thyroid The standard (LMA) offers a cartilage or vocal cords. method of establishing a clear airway in the uncon- scious patient before tracheal intubation skills and Transtracheal jet ventilation via needle. Transtracheal equipment are available. The LMA is not intended as ventilation is a life-saving measure when neither a long-term airway but only to provide emergency ventilation by mask nor endotracheal intubation is oxygenation and ventilation. possible. This technique is especially valuable for children up to 10 years of age, in whom a sufficient Favourable experience with the LMA has been ventilatory volume may be accomplished through reported in both adults and children. In addition to small catheters. being used in patients having elective surgery, the device has been employed in emergency situations It must be remembered that the only way the inspired when endotracheal intubation was impossible or not oxygen can be expired is through the upper airway. In yet available. Use of the LMA is not without the case of total upper airway obstruction, percuta- problems: oxygen desaturation and difficulty in neous transtracheal ventilation must be converted to a placement as well as aspiration around the device surgical cricothyrotomy or tracheostomy so that may occur. The LMA may, however, be used for a conventional intermittent positive pressure ventila- brief period as a bridge to re-establish airway patency tion can be initiated. The major complications of or to facilitate intubation aided by a flexible fibreoptic transtracheal jet ventilation are subcutaneous emphy- laryngoscope. Its major disadvantage of especial sema and barotrauma with resultant pneumothorax. importance in emergencies is the fact that it only seals the airway up to ventilation pressures of approximately 20 mbar. ALGORITHM FOR EMERGENCY DIFFICULT INTUBATION The ‘intubating LMA’ device is a modification of the LMA. The tube is bent and fixed at a 901 angle by a metal handle. It may be used like a conventional The optimal method of managing the patient in whom LMA, and inserted in almost any patient position, or laryngoscopy and endotracheal intubation cannot be as a guide path to the glottic opening through which a easily accomplished depends on the cause of the specially designed endotracheal tube may be passed difficulty, whether it is anticipated, the nature and blindly. urgency of securing the airway, the patient’s condi- tion, and the personnel and equipment available. The new Proseal LMA was designed as a double- Having an organized approach to alternative methods lumen LMA that has a modified shape of cuff, of securing the airway provides a basis for determin- designed to enhance the seal, and a second tube, ing the type of equipment required and minimizes which acts as a drain opening into the upper time lost in emergency situations. An algorithm for oesophageal sphincter. It can seal the airway up to this situation is given in Figure 1. the higher pressure of 32 mbar. In addition, a finger strap proximal to the anterior end of the cuff eases Continuing education and training in airway manage- insertion or may be combined with a special remo- ment for everyone who may be confronted with the vable insertion tool. AS yet it still is too soon to say treatment of emergency patients must be intense to what will be the place of the new LMA in the keep pace with the changes in standards and the management of the difficult airway. ongoing development of new devices and techniques.

EUROPEAN JOURNAL OF EMERGENCY MEDICINE (2002) 9(3) 302 THIERBACH

Ventilat. required?

yes no

direct laryngoscopy administer oxygen

yes no

A o.t. intubation o.t. intubation seems possible

no success: yes no mask ventilation?

yes no

2 intub. Attpts. optimise conditions B (FFB, FIL)

(a)

B ETC/LMA ?

yes no

secure airway surgical airway

adult: child up to 10 yrs: cricothyrotomy transtr. needle vent.

confirm tube position

(b) Fig. 1. Emergency difficult intubation algorithm.

EUROPEAN JOURNAL OF EMERGENCY MEDICINE (2002) 9(3)