Markus Weiss, MD, Department of Anaesthesia, University Children’s Hospital, Steinwiessstrasse 75, CH 8032 Zurich, Switzerland (email: email@example.com).
The incidence of unanticipated difficult or failed airway in otherwise healthy children is rare, and routine airway management in pediatric patients is easy in experienced hands. However, difficulties with airway management in healthy children are not infrequent in nonpediatric anesthetists and are a main reason for pediatric anesthesia-related morbidity and mortality. Clear concepts and strategies are, therefore, required to maintain oxygenation and ventilation in children. Several complicated algorithms for the management of the unanticipated difficult adult and pediatric airway have been proposed, but a simple structured algorithm for the pediatric patient with unanticipated difficult airway is missing. This paper proposes a simple step-wise algorithm for the unexpected difficult pediatric airway based on an adult Difficult Airway Society (DAS) protocol, discusses the role of recently introduced airway devices, and suggests a content of a pediatric airway trolley. It is intended as an easy to memorize and a practical guide for the anesthetist only occasionally involved in pediatric anesthesia care as well as a call to stimulate discussion about the management of the unanticipated difficult pediatric airway.
Difficulties with airway management in healthy children are not infrequent and present a major reason for pediatric anesthesia-related cardiac arrest, death, and brain injury in ASA closed claims analysis and the perioperative cardiac arrest (POCA) registry (1–4).
Routine airway management in otherwise healthy pediatric patients is normally easy in experienced hands and using predictors of difficult intubation such as mandibular hypoplasia, limited mouth opening, and facial asymmetry including abnormalities of the ear, stridor, and history of obstructive sleep apnea (5). However, delivery of safe anesthesia in children depends on experience, trained assistance, and other health care resources (6). Anesthesia is also frequently administered by nonpediatric anesthetists outwith children’s hospitals or ‘on-the-job trained’ personal in many parts of the world, but with considerable airway management expertise in adults (7–9).
The development of rapid hypoxemia and respiratory acidosis requires time critical, clear concepts, and strategies in anesthetized children with unanticipated difficult airways (10). However, simple pediatric difficult airway algorithms are not available and commonly locally adapted adult algorithms are in place (11,12).
The difficult airway society (DAS) produced a simple protocol for the management of the unexpected difficult airway in adults (13). The simplicity of this concept in adults could be adapted for pediatric anesthesia in the absence of a specific existing algorithm. This proposal focuses on problems commonly encountered by nonpediatric anesthetists. It is intended as a basis for discussion, not as a comprehensive review or final recommendation, for the management of the unexpected difficult pediatric airway.
Proposed algorithm for the management of the unexpected difficult pediatric airway
The basic structure based on DAS guideline (13) is illustrated in Figure 1 and includes three sections: (A) Oxygenation, (B) Tracheal intubation, and (C) Rescue.
The oxygenation and tracheal intubation sections include prevention and a basic rules part to overcome common pediatric airway problems and two plans as how to proceed when difficulties arise.
Prevention. Dedicated teaching and supervision as well as regular training in facemask ventilation in neonates, infants, and children are essential for success in all pediatric patients. Short anesthesia procedures should be utilized to gain and maintain expertise in facemask ventilation. Preparation of age-appropriate equipment, preoxygenation, and clear alternative strategies are cornerstones for successful oxygenation.
Basic rules in case of difficulties with oxygenation and ventilation. If unexpected problems with facemask ventilation arise, two principal causes need to be excluded and rectified (Table 1A).
Table 1. Causes for unexpected facemask (A) and tracheal tube (B) ventilation problems
(A) Unexpected facemask ventilation problems
Exclude and treat anatomical obstruction
Reopening the airway
Oro/naso – pharyngeal airway (nasal obstruction)
Two-hand – jaw thrust/open mouth/chin lift – facemask ventilation and two person ventilation
O Obstruction of tracheal tube (Secretions, blood, tracheal wall, pouch, tracheal foreign body)
E Equipment problems
S Stomach – increased intra-abdominal pressure
First, anatomical problems such as large adenoids and tonsils need to be considered and rectified if required. The airway needs to be reopened and a suitably sized oro/nasopharyngeal airway inserted. A two-hand facemask hold including a jaw thrust, mouth opening, and chin lift maneuver should be performed requiring two persons for successful facemask ventilation.
Second, functional airway problems are common in children and affect the upper airway (inadequate depth of anesthesia and laryngospasm) as well as the lower airway (thoracic rigidity, bronchospasm, and overinflated stomach) (14). Early recognition and treatment with either deepening of the anesthesia or administration of muscle relaxants rectify this problem and make facemask ventilation possible (15,16).
Failed oxygenation Plan A. The call for assistance is paramount with or before starting failed oxygenation Plan A. This must also include the call for the provision of the dedicated airway trolley or bag (see below).
Failure of basic facemask ventilation rules indicates either a serious functional or an underlying anatomical/structural problem (Table 1A). Provided the common functional and anatomical problems have been addressed, it is required to visualize vocal cords in the face of decreasing oxygen saturations to exclude and treat glottis foreign bodies or massive aspiration. If the vocal cords are visualized, a suitable tracheal tube is used to intubate the trachea.
If tracheal intubation rectifies the problem and improves oxygenation, the proposed procedure can be continued as planned, if not consider ventilation problems through tracheal tube as discussed below (Table 1B). If in doubt of the tracheal tube position and location and if oxygenation and ventilation do not improve, remove the tracheal tube.
Failed oxygenation Plan B. The insertion of the laryngeal mask airway (LMA) or another suitable department-specific supraglottic airway device (SAD) is the next step to improve problems with oxygenation not rectified by actions taken above or when it is impossible to visualize the vocal cords. A change of the size or make of the LMA may be beneficial. If this maneuver is successful, it is important to investigate underlying pathology, which may include flexible laryngoscopy through the LMA with subsequent tracheal intubation through the LMA (see below). The proposed surgical procedure may proceed if the problem is completely resolved or the trachea successfully intubated and oxygenation/ventilation possible. Otherwise, it is prudent to awaken patient and postpone surgery. Only in life saving surgery, it may be justified to proceed with a LMA/SAD airway and persisting doubts of its efficacy.
(B) Tracheal intubation (direct laryngoscopy)
Prevention. Regular teaching and training of direct laryngoscopy and tracheal intubation are essential for successful airway management in children as they fundamentally differ from adults in many aspects. Preparations of age-appropriate equipment and alternative strategies as well as optimal preoxygenation are cornerstones for successful tracheal intubation.
Basic rules for successful direct laryngoscopy. The first attempt should be performed in optimal conditions with age-related optimal position of the head and neck, adequate levels of anesthesia and/or muscle paralysis as well as preoxygenation. The pediatric larynx is more anterior and cephalic placed, loosely embedded in the surrounding structures when compared to adult patients and can easily be moved into a position where intubation is possible (17). External laryngeal manipulation should be used to obtain an optimal direct laryngoscopic view to minimize trauma during intubation (18,19).
Successful tracheal intubation and optimal tracheal tube position is verified clinically and with capnography after insertion of a tracheal tube in all cases.
Failed intubation Plan A. Additional experienced help needs to be called early after the first failed tracheal intubation attempt along with the provision of a dedicated airway trolley or bag. Prior to a second intubation attempt, it is important to consider whether any changes or alternatives are required to optimize conditions for the second intubation attempt. These include head and neck position of the patient, ensure adequacy of anesthesia and muscle paralysis, and alternative equipment such as different laryngoscope blades and adjuncts like a soft tip introducer (gum elastic bougie). Alternative techniques such as the paraglossal or retromolar approach using a straight blade to visualize the vocal cords may prove useful especially in children <12 months old (20,21).
New emerging visualization aids, optical and light stylets, endoscopic laryngoscopes, and others do have a place in the algorithm provided local expertise is available and maintained.
Total intubation attempts should be limited to three including a further of a more experienced intubator, as the pediatric airway is very susceptible to trauma. Consideration should be given to a more experienced anesthesiologist after two unsuccessful attempts. It is essential that oxygenation and adequate level of anesthesia are always maintained during these maneuvers. The basic oxygenation and ventilation rules should be applied between each intubation attempt as described earlier.
If a difficult intubation is encountered during rapid sequence induction, adequate depth of general anesthesia, sufficient muscle paralysis, and gentle facemask ventilation are keys to successful management (22–26).
Failed intubation Plan B. If tracheal intubation is unsuccessful despite optimizing patient positioning, technique and skills, a secondary tracheal intubation plan or ‘Failed intubation Plan B’ needs to be implemented. Prior to this, a LMA/intubating LMA (iLMA) is inserted and satisfactory ventilation and oxygenation confirmed. Fibreoptic tracheal intubation through the LMA/iLMA is achieved by mounting an adequately sized tracheal tube on the fibreoptic scope. A full or partial glottic view can be obtained in more than 50% with the epiglottis seen in 40–50% of the patients allowing the trachea to be intubated (27–32). The fiberscope is withdrawn, leaving the LMA and tracheal tube in place. If prolonged intubation is anticipated or surgical access is required, an airway exchange catheter can be used as a guide for save removal of the LMA over the tracheal tube and to reinsert a tracheal tube of choice (Table 2) (29,32–35). The patient should be oxygenated during the fiberoptic intubation and airway catheter exchange procedure as required. If apneic oxygenation techniques are used, care must be taken to avoid hyperinflation of the lungs.
Table 2. Guide for fibreoptic intubation through the laryngeal mask airway (LMA). It is important to verify the distance between the grille of the LMA and the vocal cords for the make of tracheal tubes and LMAs used in each department
aPilot balloon of cuffed tubes does not pass LMAs smaller than size 3.
bManufacturer recommends size Cook 14 F for tubes ID 5.0 and higher.
Tracheal tube size ID (mm)
Fiberoptik OD (mm)
Tracheal tube size ID (mm)
≥ID 2.5 mm
≥ID 3.0 mm
≥ID 4.0 mm
≥ID 5.5 mmb
≥ID 7.0 mm
This technique should be practiced under controlled conditions or on a mannequin before attempting this in an emergency situation. Although successfully used in adults by highly experienced users, blind insertion of the tracheal tube through the LMA/iLMA should be avoided (36).
A maximum of two attempts should be used for tracheal intubation at this stage, and consideration needs to be given to postpone surgery and wake-up of the patient if ‘Failed intubation Plan B’ fails. Alternatively, it is possible to continue using the LMA in urgent or life-threatening situations and if oxygenation and ventilation can be maintained.
Special considerations If it is impossible to advance the tracheal tube to mid-trachea do not use force but place the LMA/iLMA and perform fibreoptic laryngoscopy and tracheoscopy, to exclude or verify subglottic resistance such as tracheal stenosis, webs or pouches, or other anatomical abnormalities. Increasing difficulties in oxygenation through the tracheal tube may also be caused by prior massive pulmonary aspirations, tracheal tube displacements and obstructions, pneumothorax, large intra-abdominal pressures, and equipment malfunctions (Table 1B) (37).
The unexpected ‘can’t intubate, can’t ventilate’ situation in children is the worst case scenario and fortunately extremely scarce and probably not existing in the otherwise healthy child without signs and symptoms suggestive of a difficult airway. However, this scenario is potentially relevant for the child with a known or obvious acute severely compromised airway prior to induction of anesthesia.
If rescue techniques need to be implemented, a rigid bronchoscopy in the hands of an experienced operator and with the equipment immediately available is an option to establish an airway in patients of all ages with compromised air exchange (38,39). However, regular and specialized training is required and experienced operators are not always available.
The placement of an emergency percutaneous cricothyroidotomy cannula and/or performance of an emergency surgical cricothyroidotomy are rather anecdotic than clinically proven pediatric techniques in this situation.
Surgical cricothyroidotomy is the invasive procedure of choice for emergency access of the airway in patients, regardless of age, when conventional airway control is not possible. A rapid four-step cricothyroidotomy technique is advocated and described in adults (40,41). This technique is a temporary measure to restore oxygenation. The very small tracheal tubes to be inserted through the cricothyroid opening in neonates and small children must be considered, and a surgical incision followed by insertion of a cannula may be more appropriate (42).
The illustrated proposal is a simple, stepwise, and easy to memorize algorithm for the management of the unexpected difficult pediatric airway. It is specifically designed with‘open boxes’ to allow institutional adaptation based on the local expertise and availability of high-tec or low-tec equipment as well as their preferences as both are variable between anesthetic departments and countries. The simplicity, the inclusion of basic rules and the separation into (A) Oxygenation, (B) Tracheal intubation, and (C) Rescue make the proposal suitable particularly for nonpediatric anesthetists and nurse anesthetists familiar with mixed/adult protocols.
Although derived from the adult DAS algorithm, the main difference in pediatric airway management is that unexpected ventilation and oxygenation problems by far outnumber problems of tracheal intubation. This is primarily a result of functional airway problems rarely or not at all covered by other adult algorithms and is addressed in the prevention and basic rules section.
Prevention and basic rules
Unexpected difficulties with airway management in otherwise healthy children after exclusion of predictors of difficult intubation such as mandibular hypoplasia, limited mouth opening, and facial asymmetry including abnormalities of the ear, syndromes, obstructive sleep apnea syndrome, and stridor are very rare. If they occur, they are probably a result of inexperience or inadequate supervision and lack of pediatric airway training (6). Thorough preoperative assessment and anticipation of airway difficulties as well as education, continuous training, and regular practice in basic airway management are necessary to reduce the incidence of pediatric airway difficulties. Apart from inexperience with the pediatric airway, a majority of morbidity and mortality in pediatric airway management is attributed to a failure to recognize and overcome functional airway problems because of insufficient depths of anesthesia or muscle paralysis and not failure to intubate (1–4,15,16). Patients with a documented or anticipated difficult airway should be managed by and referred to pediatric hospitals with adequate resources. Finally, the introduction of the presented or a modified version of the proposed algorithm into clinical teaching, simulation training, and national society recommendations may improve management of unexpected difficult pediatric airways.
(A) Ventilation and oxygenation
Difficult facemask ventilation in children is scarce (<0.02%) but ventilation is never impossible to perform (43). This is in contrast to adult data where a reported 0.15% is impossible to mask ventilate despite adjuncts, experienced operators, and sufficient neuromuscular blockade (15).
Failed oxygenation Plan A. Early call for additional help and provision of suitable equipment is critical especially if the experience in pediatric airway management is limited. Functional airway problems, in particular inadequate depth of anesthesia and laryngospasm, are very common and need to be treated rapidly. However, once functional and anatomical problems have been ruled out (Table 1A), alternative causes such as a glottic foreign body (such as chewing gum, forgotten gauze pack, and regurgitation) need to be excluded by direct laryngoscopy in the face of deteriorating oxygen saturations (44–51).
It may be argued that the insertion of the LMA or SAD should precede direct laryngoscopy to address potential anatomical problems, but there are no studies or surveys supporting either view. However, it needs to be noted that there is no benefit in inserting a LMA or SAD if a foreign body obstructs the upper airway and prevents ventilation and oxygenation.
Failed oxygenation Plan B. Among supraglottic airway devices (SADs), the LMA has been demonstrated to be effective for both the difficult tracheal intubation management (as a conduit) and for unexpected and expected difficult ventilation in children (30). Differently shaped (curved) LMAs may be easier to introduce with similar or even better sealing pressures (52,53). The iLMA is only available for children weighing more than 30 kg but has been successfully used in children from 25 kg (36). Proseal® LMAs are not widely used and may be more difficult to insert (54). Although successfully described in case reports and other descriptions, the role of older (Combitube®) and newer SADs such as iGel®, Laryngeal Tube®, and Cobra® is yet to be established in children (55). Thus, only the LMA/iLMA should be inserted as a ‘Failed oxygenation Plan B’. New emerging evidence on alternative SADs may change future recommendations regarding their use. Failure to improve oxygenation and ventilation using either ‘Failed oxygenation Plan A or B’ will almost inevitably lead to (C) Rescue to be implemented.
(B) Tracheal intubation (direct laryngoscopy)
The incidence of unanticipated difficult or failed intubation in otherwise healthy children is low (56). Recent limited data suggest an incidence of 0.08% in healthy and 0.42% in all children failing tracheal intubation after three attempts (advancing the tube toward to the cords) of conventional direct laryngoscopy (43). These data are supported by a previous report of difficult intubations of 0.095% in children <16 years old with a higher incidence in children <1 year old (0.24%) (57). Basic rules for successful tracheal intubation need to be followed and regularly practiced. One important difference to the adult airway is the mobility of the laryngeal structures in order to improve direct laryngoscopy (17,18).
Successful tracheal intubation and recognition of inadvertent esophageal intubation require clinical and capnography confirmation.
Failed tracheal intubation Plan A. The incidence of unexpected failed tracheal intubation is low, and subsequently the evidence base for the use of alternative laryngoscopes, blades, and techniques is very small. It is here where the proposed algorithm allows for local expertise and preference (open-box approach). Soft tip introducers (gum elastic bougies) are useful adjuncts to help the introduction of the tracheal tube. However, they should only be used if at least part of the glottic opening is visible as to avoid unnecessary trauma of the airway (58–60).
New emerging and ‘classic’ visualization and intubation aids such as the Airtraq®, Bonfils®, Glidescope®, optical and light stylets (Shikani®, Trachlight®), and others will need to be evaluated to establish their role and application in managing the unexpected difficult pediatric tracheal intubation (61–72). Commonly, these devices were introduced as a ‘scale-down’ version of adult products without sufficient evidence from clinical studies. Currently, these devices do have a place in the proposed algorithm provided local expertise is available and maintained. It is prudent that only one or two of these devices should be selected for a department and regularly trained, to be successfully used in the unanticipated difficult airway.
Failed tracheal intubation Plan B. Fibreoptic tracheal intubation is considered the gold standard of difficult pediatric airway management. However, this technique requires, apart from appropriate equipment and assistance, considerable expertise and training. Setup and maintenance costs are high but should be included on every difficult pediatric airway trolley.
Fibreoptic tracheal intubation through the LMA/iLMA as described in the proposed algorithm is an established simple and easy to learn technique for failed tracheal intubation in children and extensively described elsewhere (27,28,30,32). A list of suitable equipment should be available and tested in advance in the department (Table 2). The tracheal intubation should be performed using a fiberscope. However, if this is not available, a ‘blind’ insertion through the LMA/iLMA (73) may be preferable to a retrograde intubation (74–76) or surgical access to the airway.
Alternatively, if experience and personal assistance is available, fibreoptic nasotracheal or orotracheal intubation can be performed. To avoid further trauma to the pediatric airway, a maximum of two attempts should be used for tracheal intubation.
The indications for the use of a tracheal tube must be critically evaluated, and if it is possible to maintain satisfactory oxygenation and ventilation with a facemask or SAD, urgent or life saving surgery can be undertaken (77).
Otherwise, the only safe option is to postpone surgery and wake-up of the patient if ‘Failed intubation Plan B’ of the unexpected difficult pediatric airway algorithm fails.
Whenever a minimal oxygenation can be maintained with an oropharyngeal airway and two-hand – two person – facemask ventilation, a surgical tracheostomy should be performed by a trained (ENT) surgeon. However, it is important to underline that this requires time and the presence of a skilled surgeon.
Alternatively, if suitable equipment and local expertise are immediately available, rigid bronchoscopy may be successful to manage the unexpected difficult pediatric airway. The rigid bronchoscope once in place can be used to place an airway exchange catheter for subsequent tracheal intubation (78).
Cannula cricothyroidotomy in infants and children has an unacceptable high incidence of complications and should therefore not be used in patients below 5–6 years as an emergency adjunct (79,80). The trachea of infants and small children has a pencil size, is elastic, flaccid, mobile and difficult to locate, and will fully collapse if transcutaneous insertion is performed. Esophageal position of the catheter has been reported in pediatric care (80). However, the technique may be successful under rigid bronchoscopic guidance and splinting of the airway.
Although for anesthesiologists, puncture techniques rather than surgical techniques are recommended (81), surgical cricothyroidotomy is the invasive procedure of choice for emergency access of the airway in smaller children. However, this is difficult because of anatomical constraints such as the close approximation of the cricoids and the thyroid cartilages. Neonates and infants lack a functional cricothyroid membrane. In neonates, it is important to appreciate that the gap between the cricoid and the thyroid cartilage does not allow passage of a 2.0-mm ID tracheal tube (42).
After care. The unexpected difficult pediatric airway can be traumatic to the patient as well as staff involved in its direct clinical management. Appropriate discussion and analysis of the event immediately and later on at local morbidity and mortality meetings are essential to carefully review the course of events and to heighten the awareness of this problem. The patient or guardian may need to be provided with a letter detailing the underlying problem if future difficult airway problems are anticipated. If access to a pediatric difficult airway register exists, patient details and associated problems may be entered there.
Difficult airway trolley
Key to the successful airway management is regular training and the instant availability of a suitable difficult airway trolley/bag in every anesthetic department caring for patients. A proposal for the ‘minimum content’ is outlined in Table 3 and may best be arranged according to the suggested (locally defined) algorithm with increasing invasiveness top to bottom. Care must be taken not to overfill such a trolley with extra ‘specialized’ equipment as not to limit the accessibility of emergency equipment.
Table 3. Minimum content of difficult pediatric airway trolley/bag with increasing invasiveness from top to bottom
Equipment and medication for basic rule procedures are not included, as they are part of the routine airway preparation. Drawers should be arranged according to a locally defined algorithm for the unanticipated difficult pediatric airway and labeled. An intubation fiberscope should be attached or immediately be available. An additional drawer for specialized equipment may be useful, as not to overload drawer 1–4. The location of the trolley/bag should be clearly marked. A checklist and instructions for sterility/cleaning need to be included, and the container should be sealed after checking to prevent unwanted removal of important equipment.
Drawer 1: Label: Failed oxygenation
LMA – sizes 1; 1.5; 2; 2.5; 3, 4, and 5 (in duplicate)
Intubating LMA (iLMA) – sizes 3, 4, and 5
Alternative supraglottic airway devices
Drawer 2: Label ‘Failed intubation Plan A’
Selection of ‘special’ laryngoscopy blades (McCoy, Wisconsin, Miller etc.)
Gum Elastic Bougie (sizes 5F and 10F), malleable stylet (size 2F and 5F)
Choice of visualization or intubation aid (depending on local preference and availability)
Different-sized cannulas for cannula cricoidotomy, Manujet, and connection tubing
Scalpel (×2), tracheal hook, artery forceps
A drawer for specialized equipment may be included separately. A locally adapted or ‘optimum content’ catering for personal or specific preferences could be set up in such a case.
The location of such difficult airway trolley must be clearly known in the department, and considerations must be given to also have this identical setup in the emergency department, intensive care, and high dependency wards.
A checklist and instructions for cleaning, sterility, and maintenance need to be included and checked after each use along with other emergency equipment. The containers should be sealed after checking to prevent unwanted removal of important equipment. Thought must be given to stock single use or reusable items.
The unanticipated difficult airway in pediatric patients is a rare event, and a clear, successive, stepwise, and memorable strategy is required to adequately approach this challenge. Apart from a simple algorithm, regular training and the availability of appropriate airway equipment (airway trolley/bag) must be provided to be successful in the pediatric patient with an unexpected difficult airway. Regular education and training must be provided to prevent and treat the unanticipated difficult pediatric airway. Careful consideration must be given to the introduction and dissemination of the proposed algorithm and suggested airway trolley content. The proposed algorithm is intended to cover these needs, stimulate discussion, and encourage new studies generating more evidence to support or improve the proposed algorithm and pediatric airway equipment.