A 35-year-old intoxicated male 179 cm tall and weighing 110 kg (BMI 34 kg·m⁻²) presents to the emergency room with a 12-inch hunting knife lodged in his upper thoracic spine after an altercation at a cottage party. Initial examination reveals normal vital signs in the prone position, a reassuring airway, and normal screening neurological exam. Initial x-ray studies confirm the knife enters at the level of T3 to T4 and traverses the right side of the spinal canal with the tip of the knife embedded in the T4 vertebral body. The neurosurgeon wishes to take the patient to the operating room for an urgent wound exploration and removal of the foreign body under general anesthesia with careful continuous neurological monitoring throughout the procedure.

What Are Your Concerns When a Patient Is Placed in the Prone Position for a Surgical Procedure?

Proper patient positioning for any medical procedure is an important consideration for a safe and successful outcome. Proper positioning provides for appropriate surgical access and guards against injury due to pressure points and strain on neurological and musculoskeletal structures. The prone position is most commonly required for surgical procedures on the spine, and for selected procedures in neurosurgery, urology, and general surgery. This position is complicated by an increased risk of stretch and pressure injury of nerves, cardiovascular instability, difficulty with ventilation, and problems with providing cardiopulmonary resuscitation as compared with the supine position. Airway considerations for patients in the prone position may include difficult access to the airway, migration of the endotracheal tube (ETT), cephalad or caudad with head extension and flexion respectively,¹ changes in ETT cuff pressure,² limited ability to reposition the head and neck for bag-mask-ventilation (BMV), and the potential development of airway edema.

This case presents a challenging situation for airway practitioners: securing the airway in an urgent setting in which the patient cannot be easily positioned supine. Limited information is currently available in the literature to assist the airway practitioner with critical decision making should they encounter this situation.

How Do You Provide Ventilation to a Patient in the Prone Position if Urgently Needed?

Options to manage the airway in a prone patient are similar to those in the supine patient. BMV should be considered the standard and attempted before other measures because the ease of BMV will guide all airway management decisions that follow. However, BMV in the prone patient can be difficult due to limited access to the airway, difficult mask seal due to no occipital support to apply counter pressure to the head,³ and lack of clinical experience performing BMV in a prone patient. It may be necessary to use a two-person BMV technique, with one person achieving a mask seal using both hands, while the second person provides manual ventilation. Provided that a good seal can be maintained between the mask and the patient’s face, BMV should be reasonably easy in a patient lying prone as gravity tends to move the tongue away from the posterior pharyngeal wall. The authors would recommend quickly moving to a two-person BMV technique (see Chapter 8) and proceeding to alternative methods of ventilation should there be any difficulty obtaining an adequate mask seal.

If BMV is not possible, an extraglottic device (EGD), such as the Laryngeal Mask Airway (LMA), can be used to provide emergency ventilation and oxygenation for a patient in the prone position. Several reports have evaluated the ease of insertion of LMA devices in the prone position in manikin studies^4,5 as well as for short elective procedures in anesthetized patients.^6–16 Despite these reports, there is still considerable debate in the literature regarding the safety of using EGDs for patients in the prone position.^17–22 A number of investigators have reported successful use of EGDs (LMA^®, LMA-Supreme^®, LMA-ProSeal^®, and others) to regain control of the airway and provide positive-pressure ventilation following ETT dislodgement in the prone position.^23–26 Insertion of the LMA in the prone patient should be attempted using the classic insertion technique recommended for patients in the supine position.²⁷ Successful insertion of the LMA may actually be easier in the prone position because gravity helps to move the tongue and epiglottis²⁸ away from the posterior pharyngeal wall and minimizes the risk of down-folding of the epiglottis.

Other EGDs, such as the Combitube™, may be used while the patient is prone, depending on the skill and experience of the practitioner, as well as the available resources. Currently there are no reports in the literature of the successful use of non-LMA derived EGDs for patients in the prone position. Therefore, the authors do not recommend the use of non-LMA derived devices in elective airway management situations or as first-line rescue devices in emergency situations.

How Do You Manage a Patient with a Difficult Airway Who Requires Prone Positioning?

Airway management of the patient with a difficult airway who requires surgery in the prone position poses unique challenges for the anesthesia practitioner. These issues can be categorized according to the etiology of the difficult airway: (1) anatomical characteristics making ventilation and/or tracheal intubation difficult and (2) cervical spine instability. If difficult laryngoscopic intubation secondary to anatomical characteristics is predicted (LEMON and CRANE, see sections “Difficult DL Intubation: LEMON” and “Difficult VL Intubation: CRANE” in Chapter 1), the technique utilized to manage the airway is dependent on whether or not oxygenation can be readily provided (by BMV, EGD, or a surgical airway), aspiration risk, the available resources, as well as the expertise of the practitioner. Once tracheal intubation has been achieved, the ETT must be carefully secured.

The situation becomes more challenging when possible cervical spine instability or spinal cord injury exists. It is generally believed that awake bronchoscopic intubation and prone positioning of the patient prior to induction of anesthesia is ideal, because it allows verification of neurological integrity prior to surgery.^29,30 However, there is no high level of evidence to support this practice. In a retrospective review of 150 patients with cervical spine injury, Suderman and Crosby³¹ found no difference in neurological outcomes following tracheal intubation awake or under general anesthesia, with or without in-line cervical spine immobilization (see section “Cervical-Spine (C-Spine) Considerations” in Chapter 17).

What Are the Options for Tracheal Intubation in the Prone Position?

In addition to direct laryngoscopic intubation, alternative intubating techniques can be considered. These include the use of a flexible bronchoscope (FB), an intubating LMA (LMA-Fastrach™, LMA North America Inc., San Diego, CA), or other EGDs designed to allow intubation through the device, light-guided intubation using the Trachlight™ (Laerdal Medical Corp., Wappingers Falls, New York, NY), and digital intubation. However, there is limited clinical information with regard to the effectiveness and safety of these techniques in patients in the prone position.

Baer³² performed endotracheal intubation using a direct laryngoscope in the prone position in 200 patients undergoing lumbar surgery. Two failed intubations occurred and these patients were then intubated in the lateral or supine positions, with difficulty.³² This experience emphasizes the importance of airway assessment and management in the supine position when difficulty is predicted. Komasawa et al.³³ evaluated the utility of a video-laryngoscope (Pentax-AWS Airway Scope) for tracheal intubation in different positions in a manikin and found the prone position to be feasible for intubation but it took longer and was subjectively more difficult for the practitioner than the supine position. There are several case reports describing airway rescue in prone patients using an FB,^34,35 intubating LMA (in a neonate),³⁶ and flexible bronchoscopy through an LMA device.²⁶ Induction of anesthesia in patients with posterior thoracic injuries in the prone position and subsequent successful tracheal intubation with direct laryngoscopy³⁷ and an intubating LMA^38,39 have also been reported. We believe that tracheal intubation of patients in the prone position should be reserved for special and rescue situations and for practitioners with the necessary skills and resources. For elective and non-urgent tracheal intubation of patients requiring prone positioning, it would be prudent to secure the airway in the supine position which is most familiar to the airway practitioner.

However, intubation in the prone position may be necessary if:

1. 
   

   ventilation and oxygenation are ineffective using BMV, the LMA, or other EGDs,

   
   
2. 
   

   ventilation using BMV, the LMA, or other EGDs is adequate but a definitive airway is desired (e.g., prolonged case, risk of aspiration),

   
   
3. 
   

   transfer of the patient to the supine position is impossible, or associated with extreme risk.

Can Intubation be Performed in the Lateral Position?

While transfer of the patient to the supine position would be ideal, it could be difficult to achieve in a timely manner and is not without considerable risk depending on the situation. Therefore, it is desirable to have several alternative approaches for tracheal intubation in this particularly difficult situation.

If it is feasible to place the patient in a lateral position, the left lateral decubitus is preferred by some practitioners for laryngoscopy and intubation, as gravity will help to displace the tongue as well as secretions to the left and facilitate visualization of the glottis.³ However, others prefer the right lateral decubitus position as the practitioner’s left arm has more room to maneuver during the procedure. The tongue can still be easily displaced by the laryngoscope in the right lateral decubitus position. Nathanson et al.⁴⁰ found tracheal intubation of a manikin in the lateral position to be more difficult than in the supine position. The ease of intubation increased with each subsequent attempt, indicating that practitioner experience was a confounding factor.^33,40 An assistant may be necessary to stabilize the head, neck, and body while performing intubation of a patient in the lateral decubitus position.

Blind endotracheal intubation techniques using the intubating LMA (LMA-Fastrach™, LMA North America Inc., San Diego, CA) and the lighted stylet have also been described with a patient in the lateral position.^41–43 Practitioner’s experience with these intubation techniques will improve the chance of success. However, blind techniques should only be attempted after direct or indirect visualization techniques have failed, especially in trauma patients with the potential for a full stomach and if there is a possibility of anatomic distortion of the airway.

What Are the Options for Positioning This Patient for Induction of General Anesthesia?

This is a complex clinical situation that has to take into consideration each of the following prior to developing an appropriate management plan:

1. 
   

   urgency of the situation (e.g., presence or absence of respiratory difficulties and hypoxemia),

   
   
2. 
   

   risk of regurgitation and aspiration (full stomach secondary to drinking at a party),

   
   
3. 
   

   the extent of the patient’s spinal injury or other associated injuries (following an altercation at a party),

   
   
4. 
   

   current hemodynamic status and potential for hemodynamic changes,

   
   
5. 
   

   the presence of any neurological compromise and degree of concern for impending neurological compromise,

   
   
6. 
   

   the level of the patient’s anxiety and willingness to cooperate,

   
   
7. 
   

   the position of the patient at presentation.

Ultimately, the anesthesia management plan will weigh the risks and benefits of airway interventions and induction of general anesthesia—keeping the patient in his current position with the risks and benefits of repositioning the patient into a potentially more favorable position. If the risk of neurological compromise is deemed to be high, transferring the patient from supine/sitting to prone or prone to supine would be unacceptable. It would be prudent to manage the anesthesia and airway with the patient at or close to his position at presentation. Regardless of the final plan for positioning the patient, careful consideration must be given to securing the equipment, personnel, and resources required to carry out the management plan. Clear and concise communication must be provided to all team members regarding the sequence of steps involved in the management plan (Plans A, B, C, and D).

How Would You Position This Patient for Airway Management if He Presented in the Sitting or Upright Position?

If the patient presenting to the emergency department in the sitting position with stable neurological and hemodynamic status can be transported to the operating room (OR) in sitting position with sufficient support and care. There are several options for positioning the patient for anesthetic and airway management:

1. 
   

   His airway can be managed awake with topical anesthesia and the patient can then be turned prone before induction of anesthesia.

   
   
2. 
   

   Two OR tables can be placed side-by-side with a sufficient gap to allow the foreign body to rest between the tables with the patient supine. These OR tables can be adjusted in tandem into an appropriate position (supine, reverse Trendelenburg, semi-sitting, or beach chair) prior to transferring the patient to them (see Figure 38–1). This method may require a third OR table to be present in the room for transferring the patient to the prone position for the surgical procedure after securing the airway and induction of general anesthesia. The length of the foreign body that remains outside of the thorax is a concern as a particularly lengthy foreign body could get caught on one of the OR tables straddling the foreign body while transferring the patient to the prone position.

   
   
3. 
   

   The patient can be transferred to the supine position on an OR table from the sitting position such that the foreign body will lie above the head of the table. With this approach, support of the patient’s shoulders and head will be needed as they will also lie above the head of the OR table. This support of the head and shoulders can be achieved with an extra side table, OR table, stretcher, or other device adjusted to the right height (see Figure 38–2).

   
   
4. 
   

   The patient can be transported to the OR in prone position and then transferred to the OR in the same position. The airway and anesthesia can be managed in the prone position. The risks and benefits of this option will be discussed later in the chapter.

   
   
5. 
   

   The patient can carefully be placed in the lateral position for airway management before being turned into the prone position for the surgical procedure.

How Would You Position This Patient for Airway Management if He Presented in the Prone Position?

For the patient with a dorsal foreign body presenting in the prone position, the options are as follows:

1. 
   

   Carry out airway and anesthetic management with the patient in his current position (prone on a stretcher or bed). Although this option avoids moving or transferring the patient prior to airway management, the patient would still need to be transferred and positioned on the OR table. The authors do not recommend this option.

   
   
2. 
   

   Transfer the patient to the OR table in their final prone position and manage the airway and induction of general anesthesia in that position. This would allow proper surgical positioning prior to airway management and ensure the patient was neurologically intact prior to induction of anesthesia and the start of the surgical procedure.

   
   
3. 
   

   Arrange OR equipment for anesthetic management in the supine position (see above) and transfer the patient from the prone to supine position for airway management.

   
   
4. 
   

   Turn the patient into the lateral position for airway and anesthetic management (see above).

If the Patient was Cooperative, Could This Patient’s Airway be Managed Awake?

If the patient was cooperative and could be safely positioned to allow for awake airway management, there are no contraindications to manage this patient’s airway awake. For a patient presenting in the sitting position, tracheal intubation could be achieved as described in the previous section. During airway topicalization or awake intubation, it is possible that the patient could change his position by coughing or become agitated and combative. Any patient movement could potentially further impale the foreign body into the spine. Excessive body movement can be minimized by a gentle unhurried airway topicalization technique and by having assistants support the patient’s body position during the procedure.

Performing an awake intubation with a patient already in the prone position may be more challenging. Although an OR table could be maneuvered to place the patient in a reverse Trendelenburg/chair position with the patient’s head extending over the end of the OR table, it would be difficult to arrange this position with the appropriate bolsters in place. In addition, any patient discomfort while preparing for or during awake intubation could result in patient movement which could result in the patient falling off the OR table. Lastly, most anesthesia practitioners and assistants are unfamiliar with awake intubation in a prone patient and the lack of confidence and preparation may jeopardize the success of the technique and the ability to manage any potential complications.

Can Induction of Anesthesia in the Prone Position be Safely Performed in This Patient?

There is considerable debate in the literature about the merits of prone positioning and induction of general anesthesia for elective cases. An increasing number of studies including a substantial number of patients report induction of anesthesia in the prone position and report the level of complications to be similar to induction of general anesthesia in the supine position. However, extrapolation of this limited evidence to clinical scenarios different from the patient populations and procedures in those reported studies should be done with great caution. All of the reported studies which include induction of general anesthesia in the prone position were carried out in elective patients, the majority of whom were not obese, and always stressed the importance of the need to be able to quickly turn the patient supine should any difficulties present themselves during airway management. Therefore using currently available evidence, inducing general anesthesia in the prone position for elective surgical patients does not appear to offer the widest margin of safety.

There are several case reports of the induction of general anesthesia and airway management in the prone position for traumatic posterior thoracic injuries.^37–39 Agrawal et al.³⁹ used an inhalation induction followed by tracheal intubation through an ILMA technique for a 25-year-old patient with a normal airway placed in the prone position because of extensive open back wounds. Van Zundert et al.³⁷ describe successful tracheal intubation using direct laryngoscopy in a non-obese patient placed in prone position with a pair of scissors lodged in her spine. Another case report of a patient with a normal airway and a traumatic knife injury to the lumbar spine was managed with induction of anesthesia and intubation in the prone position using an intubating LMA.³⁸ Assuming that careful consideration is given to select and prepare the method of airway management, this could be a reasonable management plan if the risks of positioning the patient in a more conventional position for airway management are deemed unacceptably high.

How Can Endotracheal Intubation be Performed in the Prone Position in the Patient Presented Here?

As stated above (see section “What Are the Options for Tracheal Intubation in the Prone Position?” in this chapter), successful tracheal intubation has been reported using a variety of techniques. While the practitioner may be unfamiliar with the awkward prone position, tracheal intubation using an FB can be performed in the prone position with the OR table in a reverse Trendelenburg position and an assistant supporting the patient’s head (see Figure 38–3). With an assistant holding the patient’s head, tracheal intubation by direct laryngoscopy can also be performed in the prone patient by the airway practitioner who is positioned at the head of the patient facing caudad and who uses the right hand to insert the laryngoscope into the pharynx and expose the glottis (Figure 38–4). Operating the laryngoscope with the right hand while the practitioner faces the prone patient allows the laryngoscope blade to displace the tongue in the usual manner—away from the right side of the patient’s mouth. The practitioner then uses the left hand to insert the ETT into the trachea. This technique of laryngoscopic intubation in prone patients has been shown to be effective (99% success rate) and safe.³² Alternately, direct laryngoscopy and intubation can be performed in a more conventional manner from either side of the patient (Figure 38–5). An assistant can turn the patient’s head to the right and elevate the right shoulder slightly to facilitate access to the mouth. The head and neck can also be placed in the familiar sniffing position. The additional concerns with this technique in the patient requiring spinal precautions would make the former technique (approaching the airway from the head of the bed) more favorable.

Agrawal et al.³⁹ described the successful use of the ILMA for tracheal intubation in a patient in the prone position who presented with injuries precluding supine positioning. The ILMA can provide a conduit through which an ETT can be advanced into the trachea blindly, or with the aid of a lightwand, or the FB (see Chapter 12). However, insertion of an intubating LMA (as compared to the LMA-Classic) can be difficult in the prone position. Alternatively, following successful placement of the LMA-Classic, an FB can be used to facilitate tracheal intubation through the EGD (see section “Can the Flexible Bronchoscope be Combined with Other Intubation Techniques?” in Chapter 10). Flexible bronchoscopic guided intubation can be accomplished by passing a pediatric FB with an ensleeved Aintree Intubation Catheter (AIC, Cook Medical Inc. Bloomington, IN) into the trachea through the “aperture bars” of an in situ LMA-Classic. The bronchoscope and LMA-Classic can then be removed leaving the AIC in the trachea. An ETT ≥7.0-mm ID can be advanced over the AIC into the trachea.