Chapter 56. Airway Management in Austere Environments

As an anesthesia practitioner, you were in a developing country on a short-term, 2-week mission with a team of plastic and maxillofacial surgeons. The team's mandate was to operate on patients with unrepaired cleft lips and palates. As word spread in the area of the team's successes, on the final day of the mission a 12-year-old boy was brought to the clinic. One year before, the boy had sustained significant burns to his lower face, neck, and chest. No surgical remediation had been undertaken and he now had severe burn contractures (Figure 56-1).

In the developed world, about 1:50 general anesthesia cases will present with difficult tracheal intubation; 1:75 will result in a failed intubation; and a failure to intubate and to ventilate occurs in 1:1000 to 1:12,000. Obstetrical anesthesia is particularly challenging in this regard, as the airway may be complicated by edema related to toxemia or prolonged labor (see Section 1.2.1). Although the principles of airway management are similar worldwide, the anesthesia practitioner in the developing world can expect to face challenges both unrelated, and related, to difficult airway anatomy (Table 56-1). A variety of difficult conditions will be encountered, often in later stages of evolution, presenting greater challenges with higher airway acuity. Pathology less familiar to the average practitioner can also be expected. A higher proportion of anesthesia practice appears to be made up of pediatric and obstetrical patients.

56.2.1 What Are the Risks Inherent in Airway Management in Austere Environments?

Forty years of intense commitment has greatly reduced avoidable anesthesia-related mortality in wealthy countries to a rate of about 1/56,000 anesthetics (1/180,000 when anesthesia is the sole cause of mortality and morbidity), and airway misadventure is no longer the primary reason for seriously adverse outcome.1 Training in airway management has advanced, guidelines and standards have been introduced, technology has evolved immensely, and a culture of safety is in place.2,3 Sadly, such benefits have been largely restricted to the few who live in relatively privileged societies. Published mortality due to airway misadventure in less resourced areas can vary from 100 to 1000 times that in affluent societies. 4-7 Indeed, in one report, the avoidable mortality from airway-related causes was 1/183 anesthetics.7 Obstetric anesthesia is a particular risk in this regard.8

The challenges facing developing countries are far more profound than the unavailability of the latest aids for tracheal intubation. The greatest barrier is the inability through lack of resources to provide adequate training, adequate supervision, essential monitoring techniques, sustainable organizational structure, and a modern system of quality review. One major priority, universal pulse oximetry, is lacking, but so too are vigorous educational support, mentorship, and team building.

56.3.1 What Are the Equipment Considerations for Difficult Airway Management in the Developing World?

Aggressive attention to the needs of the developing world has been undertaken by the international anesthesia community since 1989,2 and a series of standards have evolved, most recently the WHO Guidelines for Safe Surgery.9 These guidelines are sensitive to an immense global variation in resources and capacities, and standards are stratified to reflect what is possible for most regions.

56.3.1.1 Equipment Recommended for Level 1 Facilities: Small Hospitals or Health Centers

Such facilities provide minor surgery, normal obstetric delivery, and stabilization of emergencies. Level 1 facilities are staffed by paramedical staff, anesthetic officers, nurses, and midwives. In many environments, the supply of compressed gases is unreliable and expensive, meaning that oxygen concentrators, and draw-over anesthesia offer significant advantages.10 If only a single laryngoscope blade can be made available, it perhaps should be a Macintosh #4, as the tip of the blade can be used for neonates and children. WHO guidelines for medication and equipment availability in Level 1 facilities appear in Table 56-2 and 56-3.

56.3.1.2 Equipment Recommended for Level 2 Facilities: District or Provincial Hospitals

Level 2 facilities undertake procedures such as caesarean section, laparotomy, and internal fixation of fractures that do not require a high level of specialization and technology. Such facilities have at least one trained anesthesiologist, with district medical officers, senior clinical officers, nurses, and midwives. There are one or more resident surgeons and obstetricians, and there are visiting specialists. Additional drugs and equipment are available to supplement those found in Level 1 facilities (Tables 56-4 and 56-5).

56.3.1.3 Equipment Recommended for Level 3 Facilities: Referral Hospital

Such facilities usually have the capacity to undertake facial surgery, intracranial surgery, bowel resection surgery, pediatric and neonatal surgery, thoracic surgery, major eye surgery, major gynecological surgery, and the management of critically ill patients. Personnel include surgical, anesthesia, and critical care subspecialists. Available recommended medications and equipment (in addition to those available at Level 1 and 2 facilities) appear in Tables 56-6 and 56-7.

These guidelines provide a useful measure of the resources which will likely be encountered in developing countries. At times, resources available may exceed those recommended in the WHO guidelines. Not infrequently, however, material support suggested in guidelines may not be available.11 In addition, teaching clinicians can expect to encounter local practitioners with less airway management experience due to the extensive use of local and regional anesthesia for surgical procedures.

56.3.2 What Are Portable Equipment Considerations for Volunteers on Missions?

There is a dichotomy in the needs for difficult airway equipment in austere environment practice, depending on the nature of the mission. Longer-term teaching missions generally involve teaching local practitioners to use equipment already present (or easily obtained) and maintained in the environment. In general, equipment inventory will reflect WHO standards. In contrast, with short-term service missions, a traveling team arrives to directly provide medical care, and airway equipment is generally transported in and out with the team.12

56.3.2.1 Airway Equipment Considerations for Longer-Term/Teaching Missions

In general, a fundamental premise of longer-term teaching missions is to teach and use airway equipment that is locally sustainable. A "locally sustainable" device is defined as one that is already present in the environment, or can readily be obtained from that location (Tables 56-3, 56-5, and 56-7). In addition, it must be easily disinfected and should be simple to maintain or repair if broken. If electronically powered, the device should have a reliable power source, batteries or otherwise, and in this context, it must be stressed that electrical power (and compressed gases), are often unreliable in disadvantaged countries. Generally, equipment must be reusable, and it must be assumed that any single-use items will be reused.

Even if a device can be obtained and maintained, other factors must be considered. Introducing devices with unfavorable learning curves, or complex storage or disinfection needs, should be discouraged. Donation of equipment that is fragile or requires frequent servicing (eg, a flexible bronchoscope with a video tower), while well-meaning, can be futile and counterproductive in an austere environment. If such a device is presented, it helps to designate one local practitioner as champion for the product, charged with responsibility for ensuring it is used, cleaned, and stored appropriately.

56.3.2.2 Equipment Considerations for Short-Term/Service Missions

Airway equipment considerations differ for a short-term service mission (Table 56-8). Under these conditions, routine and difficult airway equipment is transported by the team, such equipment being limited only by its portability and robustness. The equipment should ideally be available in adult and pediatric versions, given the high occurrence of pediatric cases. If battery powered, sufficient batteries should also accompany the equipment, and disinfection requirements should be straightforward. It should be noted in this context that many practitioners consider the use of outdated medications or equipment unacceptable.

56.3.3 What Can Be Done to Disinfect Equipment in an Austere Environment?

Disinfection methodologies of the developed world are seldom possible in austere environments and a great deal of ingenuity can be found in the methods of steam/sterilization, hypochlorite (bleach), boiling, formaldehyde, and chlorhexidine/cetrimide. Balance is often required between levels of sterility assurance and the possibility of doing a greater good with surgery. High-level disinfection may have to be accepted rather than sterilization. A sampling of common practice guidelines can be found in Tables 56-9, 56-10, and 56-11.

56.4.1 Should a Patient with a Very Difficult Airway Be Managed in the Austere Environment at All?

There is no shortage of very difficult airway anatomy in the developing world. If presented with such a case, a methodological approach should be undertaken. For a service mission with defined objectives, a very high acuity case may fall outside the team's capabilities, for example, due to extreme airway considerations or the anticipated significant need for blood products. Even if the case may be possible from a surgical and anesthetic perspective, postoperative requirements may exceed available infrastructure, for example, the lack of an intensive-care facility with ventilators, or suction and humidification for postoperative management of a patient with a fresh tracheotomy. Careful consideration must always be given to the ultimate patient interest (eg, in an emergency situation) and to the reality that concepts of cause and effect can vary significantly over a breadth of environments. Especially in children, it may be possible to arrange care, through aid organizations, in a more favorable environment.

56.4.2 Can the Surgical Procedure Be Done with Local or Regional Anesthesia?

Using regional or local anesthesia may allow a procedure to occur without airway manipulation. Equally, local anesthesia may allow a minor surgical revision of difficult airway anatomy that would then allow safer induction of general anesthesia, for example, the partial release of a burn contracture.

56.4.3 If General Anesthesia Is Required, Can the Airway Be Safely Secured Post-Induction?

The guiding principles of the ASA Difficult Airway Algorithm (see Section 2.4.2) are still applicable in the less developed world, despite the common absence of flexible bronchoscopy and newer airway adjuncts. Awake intubation with blind nasal techniques (see Section 11.5), retrograde catheters (see Section 11.6), manual techniques (see Section 11.4), and direct laryngoscopy are the rule for the difficult airway in austere environments—and creative approaches in these regards have been reported. For example, 14 to 16 French gauge suction catheters, or hollow ureteric dilators, can be used as anterograde guides in retrograde intubations.13,14 It should also be emphasized that there are a number of thin flexible scopes that can be used for intubation, including ureteroscopes. An interesting report suggests that in the event of an inability to negotiate a nasotracheal tube through the larynx in children, the tube could be left in the esophagus and an Eschmann Tracheal Introducer placed in the alternative nostril. The blindly placed bougie will often find its way into the trachea.15

Notwithstanding such creativity, equipment challenges and a lack of patient cooperation due to language barriers as well as patient age may militate against successful awake intubation in the patient with a difficult airway. Prerequisites for anesthesia induction and pharmacologic paralysis in the patient with significant predictors of difficult direct laryngoscopy include: the absence of obstructing upper airway pathology; anticipated successful BMV and rescue oxygenation by EGD or cricothyrotomy; a reasonable chance of successful intubation by direct laryngoscopy; skills in the use of alternative intubation devices (if available); and the presence of skilled help. It also should be borne in mind that a case traditionally done with endotracheal intubation might be safely done with an extraglottic device in a patient with a difficult airway. An interesting report has described the use of the modified nasal trumpet, a #7.0 or #8.0 standard nasopharyngeal airway with an added distal fenestration and fitted with a 15 mm adaptor to permit connection to an anesthesia circuit.16 Considerable judgment is required across the spectrum of clinical circumstances.

56.5.1 Are There Likely to Be Difficulties with BMV in This Patient?

This patient's contractures and facial deformity will make mask application very difficult. Burn contracture will also preclude airway-opening maneuvers, such as head extension and jaw thrust. BMV is thus predicted to be very difficult in this patient.

56.5.2 Are There Likely to Be Difficulties in Placement of an Extraglottic Device in This Patient?

It is unlikely that sufficient mouth opening can be achieved in this patient to allow the insertion of an EGD. Furthermore, by limiting head and upper neck extension (see Section 1.6.3) and distorting the airway, the neck and upper torso contractures may create difficulty with EGD passage into the pharynx, or seat and seal properly once there.

56.5.3 Are There Likely to Be Difficulties with Laryngoscopy and Orotracheal Intubation in This Patient?

Tracheal intubation of this patient by direct laryngoscopy is likely to be impossible on the basis of limited mouth opening and severely limited head and neck extension. In addition, burn contracture will make the mandibular space stiff and noncompliant, so that tongue displacement and compression will be difficult.

56.5.4 Would Cricothyrotomy Be Feasible in This Patient?

Scarring and contracture would make cricothyrotomy almost impossible in this patient.

56.5.5 What Coexisting Medical Problems Can Be Anticipated in This Patient?

The patient's contractures are likely to have compromised nutrition and general conditioning; a chronic airway obstruction may be present, and there may be chronic reflux and aspiration. In addition, if a substantial part of the chest was involved with the burn, scarring and contracture of the chest will significantly reduce the compliance of the lungs (restrictive pulmonary dysfunction).17

56.5.6 What Was Done in This Case?

A feasibility assessment was performed. Equipment for skin harvesting was available, and as the area requiring grafting was limited, the need for blood products was judged unlikely. Local medical and nursing expertise was deemed capable of taking on postoperative care. Airway assessment suggested that awake tracheal intubation would be safest for the required general anesthetic. Unfortunately, a flexible bronchoscope was not available, and patient cooperation could have been an issue.

An interpreter was obtained, the patient was taken to the operating room, and intravenous access obtained. Local anesthesia was used to enable release of some of the contractures limiting mouth opening, jaw mobility, and head extension. Thereafter, with the patient still awake, a mixture of local anesthetic jelly and a small amount of sweetener was used to anesthetize the mouth and pharynx, and a size 2.5 LMA was inserted (as previously described).18 This was well tolerated. Good seating of the LMA was confirmed, and with the patient breathing spontaneously, draw-over inhalational anesthesia was introduced. Under general anesthesia and with unobstructed spontaneous ventilation, further contracture release with skin grafting was safely completed.

Airway management in the austere environment of many developing countries can be challenging on many fronts: the advanced state of the pathology encountered; equipment availability; and possibly substandard local hospital infrastructure and staffing. The practitioner teaching or practicing in these conditions must be resourceful and sensitive to local culture and conditions. Cases presenting with difficult airway considerations should be approached bearing in mind the limitations of both intra- and postoperative resources.