Transmylohyoid Orotracheal Intubation in Surgical Management of Canine Maxillofacial Fractures: An Alternative to Pharyngotomy Endotracheal Intubation Jason W. Soukup, DVM, Diplomate AVDC, and Christopher J. Snyder, DVM, Diplomate AVDC Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin‐Madison, Madison, Wisconsin
Corresponding Author Jason W. Soukup, DVM, Diplomate AVDC, Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin‐Madison, 2015 Linden Drive, Madison, WI 53706. E‐mail: [email protected]. Submitted July 2013 Accepted November 2013 DOI:10.1111/j.1532-950X.2013.12138.x
Objective: To describe the surgical technique of transmylohyoid orotracheal intubation in surgical management of maxillofacial fractures in dogs. Study Design: Case series. Animals: Dogs (n ¼ 4) with maxillofacial fractures. Methods: Transmylohyoid orotracheal intubation was used for airway management of dogs undergoing surgical repair of maxillofacial trauma. A stoma was surgically created by an incision through the skin, subcutaneous tissue, and mylohyoideus muscle immediately medial to the lingual cortex of the mandible at the level of the mandibular 1st molar tooth, so that an endotracheal tube could exit the oral cavity between the mandibular bodies bypassing the dentition. Results: Transmylohyoid orotracheal intubation allowed excellent surgical visibility of the oral cavity and intraoperative control of occlusion during surgery. No complications were encountered during the procedure and the stoma healed without complication. Conclusions: Transmylohyoid orotracheal intubation is a safe, simple, and effective technique for bypassing the rostral oral cavity and dentition during surgical management of maxillofacial fractures.
Simultaneous return of proper occlusion and fracture reduction is the primary objective of maxillofacial fracture repair.1 To achieve this objective, intraoperative control of occlusion, by bypassing the dentition, must be obtained. In dogs and cats, this has typically been achieved by using pharyngotomy endotracheal intubation.2,3 However, because of the complex neurovascular anatomy at the pharyngotomy site, this procedure inherently carries a potential risk of iatrogenic complications. We report our experience using a novel alternative approach, transmylohyoid orotracheal intubation that minimizes these risks, in 4 dogs undergoing maxillofacial fracture repair.
MATERIALS AND METHODS Surgical Technique The airway was secured by orotracheal intubation immediately after induction of general anesthesia. Dogs were positioned in dorsal recumbency and the skin on the ventral aspect of the mandible was clipped and aseptically prepared for surgery. An incision with a length approximating the diameter of the endotracheal tube to be used was made through the skin and subcutaneous tissues immediately medial to the ventral border of the mandible at the level of the mandibular 1st molar tooth (Fig 1A and B). While maintaining contact with the lingual
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cortex of the mandible, blunt dissection was performed dorsally through the subcutaneous tissues and mylohyoideus muscle using a combination of Metzenbaum scissors and hemostats (Fig 1C). An intraoral incision was then made in the mucosa overlying an inserted hemostat tip immediately lingual and ventral to the mucogingival junction of the lingual mucosa of the mandibular 1st molar tooth (Fig 1D) and the resulting tunnel widened as needed to accommodate a reinforced cuffed endotracheal tube. In dogs 1–3, a large forceps (i.e., Carmalt) was inserted through the natural orifice into the oral cavity, through the oral mucosal incision to exit the oral cavity through the ventral skin incision, and used to grasp the cuffed end of the reinforced transmylohyoid orotracheal tube (Fig 1E), which was pulled into the oral cavity (Fig 1F). The initial orotracheal tube was removed from the trachea and the transmylohyoid orotracheal tube was retroflexed and guided through the laryngeal inlet and into the trachea (Fig 1G). Alternatively, as in dog 4, the non‐cuffed end of the traditionally placed endotracheal tube can be pulled through the stoma to exit the oral cavity. In dog 4, the cuff balloon of the endotracheal tube was passed from the oral cavity through the stoma (Fig 2A), then a Carmalt forceps was inserted through the stoma into the oral cavity and used to grasp the non‐cuffed end of the traditionally placed reinforced endotracheal tube (Fig 2B), which was then pulled through the stoma (Fig 2C).
Veterinary Surgery 44 (2015) 432–436 © Copyright 2014 by The American College of Veterinary Surgeons
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Transmylohyoid Orotracheal Intubation
Clinical Report
Figure 1 Photograph of a cadaver demonstrating transmylohyoid orotracheal intubation. (A) Location of the skin incision at the level of the mandibular 1st molar tooth; (B) ventral cortex of the mandible (þ) and the mylohyoideus muscle ( ); (C) blunt dissection through the fibers of the mylohyoideus muscle; (D) mucosal incision over a hemostat inserted through the extraoral surgical approach; (E) Carmalt forceps inserted through the surgical stoma from the oral cavity to grasp the cuffed end of the reinforced endotracheal tube; (F) reinforced endotracheal tube being pulled through the surgical stoma and into the oral cavity; (G) transmylohyoid orotracheal tube being retroflexed and inserted into the trachea to complete the transmylohyoid orotracheal intubation.
The transmylohyoid orotracheal tube was connected to the anesthetic circuit and secured to the dog according to clinician preference. At the end of the procedure, the transmylohyoid orotracheal tube was removed through the incision and the dog re‐intubated by the orotracheal method for recovery or any additional procedures. In dogs 1 and 2, the surgical site was closed. Subcutaneous tissues and the mylohyoideus muscle were closed with a 4‐0 synthetic absorbable suture in a simple continuous pattern. The ventral skin incision was sutured with a 4‐0 synthetic non‐absorbable suture in a simple interrupted pattern and the oral mucosal incision left to heal by second intention. In dogs 3 and 4, the entire surgical site was left to heal by second intention.
Four dogs (Siberian Husky, Australian Shepherd, Irish Terrier, Yorkshire Terrier; 3 females [1 intact, 2 spayed] and 1 intact male) requiring mandibular fracture management were recruited for this study. Mean dog’s age was 30.6 months (range, 2.5–108 months) and mean weight, 9.4 kg (range, 3.41–17.5 kg). Maxillofacial trauma was either from altercation with another dog (dogs 1, 3, and 4) or altercation with a cow (dog 2). Preoperative hematologic and serum biochemical profile findings were unremarkable. All dogs had preoperative CT for diagnosis and surgical planning. Imaging findings were a transverse, mildly displaced, left (dogs 1, 3), right (dog 4) or bilateral (dog 2) mandibular fracture. The fracture was comminuted in dogs 1 and 3. Dog 1 also had a mildly displaced, comminuted left maxillary fracture and a ventrally luxated left nasal bone. Fractures were located at the level of the 1st molar (dogs 1, 4), 1st premolar (dog 2) and junction of the mandibular body and mandibular ramus (dog 3). Typical time to perform transmylohyoid orotracheal intubation was 10 minutes. Dogs were treated in dorsal recumbency and intraoperative control of occlusion was achieved by tying roll gauze around the upper and lower jaw just caudal to the canine teeth (dog 1), by securing a fiber‐ reinforced, bondable reinforcement dental ribbon to the buccal surface of each tooth from the left mandibular 1st molar tooth to the right mandibular 1st molar tooth with a flowable, light curable dental composite (dog 2) or by securing the transmylohyoid orotracheal tube tie around the dogs upper and lower jaws (dog 3). The method of fracture fixation (interdental wire and interdental acrylic splint) prevented the upper and lower jaws to be fixed in occlusion in dog 4. The mandibular fractures were managed either with wire osteosynthesis, interdental wiring, intraoral acrylic splinting or a combination thereof. In dog 2, the intraoral acrylic splint was reinforced with a K‐wire. To reduce the luxated left nasal bone in dog 1, a periosteal elevator was inserted into the left nasal cavity and dorsal attraction was applied. The non‐ displaced maxillary fracture was not treated. Postoperative occlusion was assessed and determined to be normal in all 4 dogs. After completion of fracture reduction, the transmylohyoid orotracheal intubation tube was removed and all dogs were re‐intubated by an orotracheal approach for recovery. Three dogs (dogs 1, 2, and 4) were administered systemic antimicrobials to prevent infection of an open fracture site. Dogs 2 and 4 had oral chlorhexidine rinses to minimize biofilm buildup on the interdental splint. Pre‐/intraoperative pain control consisted of bupivacaine regional anesthesia (dogs 1– 4), subcutaneous meloxicam injection (dog 3), IV fentanyl/ lidocaine/ketamine continuous rate infusion (CRI) (dogs 2 and 4), IV morphine/lidocaine/ketamine CRI (dog 1) and IV fentanyl CRI (dog 3). Postoperative pain control consisted of IV CRI of fentanyl (dogs 2–4) or morphine/lidocaine/ketamine (dog 1), transdermal fentanyl (dogs 2–4), oral carprofen (dogs 1 and 2), oral acetaminophen (dog 4), and oral tramadol (dogs 1–4). No complications related to the transmylohyoid
Veterinary Surgery 44 (2015) 432–436 © Copyright 2014 by The American College of Veterinary Surgeons
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Figure 2 Photograph of a cadaver demonstrating repositioning a conventional reinforced orotracheal tube through a transmylohyoid approach. (A) The orotracheal tube cuff balloon is being pulled from the oral cavity through the surgical stoma; (B) the rostral end of the orotracheal tube is being grasped by a Carmalt forceps inserted through the surgical stoma and is retroflexed, and (C) withdrawn through the stoma to exit the oral cavity. Note that the tube connection port has been removed to facilitate transportation of the tube through the surgical approach.
orotracheal intubation surgical site were seen immediately postoperatively or at a 2‐week follow‐up in any of the dogs. All dogs had fracture healing with normal occlusion.
DISCUSSION There are few clinical scenarios in which bypassing the dentition during endotracheal intubation is as vital to clinical success as in the management of maxillofacial fractures. Simply achieving interdigitation of the fracture segments without intraoperative control of occlusion is of little long‐term benefit to the patient with maxillofacial fractures. Not only will the patient suffer from chronic malocclusion and its secondary complications (pain, dental trauma, and periodontal disease), the resultant abnormal tooth‐to‐tooth contact will impart abnormal forces on the healing fracture and may increase the chance of a non‐ or mal‐union.1 By controlling occlusion during fracture fixation, the clinician helps to ensure that the bone fragments are correctly aligned and provides the best possible long‐term outcome.4 The endotracheal tube must bypass the dentition and, therefore, cannot enter the oral cavity through the natural orifice. Several methods for bypassing the oral cavity have been described. Tracheotomy achieves the necessary bypass, but may have potential morbidity.5 Although not anatomically possible in dogs and cats, nasotracheal intubation has been used when the orotracheal method is not possible in rabbits and llamas6,7 and is the standard method of intubation in people who do not have either a nasal‐orbital‐ethmoid fracture or a skull base fracture.8 Pharyngotomy endotracheal intubation would have allowed for similar intraoperative control of occlusion and likely would have achieved the same result in all 4 dogs; however, transmylohyoid orotracheal intubation achieved the surgical principles of maxillofacial fracture repair with the benefit of (1) shorter surgery time, (2) a simpler surgical approach, and (3) lower inherent risk of iatrogenic
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complications. Transmylohyoid orotracheal intubation was successfully used in a dog of bilateral rostral mandibular fractures. In dogs of bilateral caudal mandibular fractures, pharyngotomy endotracheal intubation may be preferred over transmylohyoid orotracheal intubation. Although we could not find published data reporting the complication rate or nature of pharyngotomy endotracheal intubation, anatomic familiarity and clinical experience suggests there is an inherent, and potentially serious, risk of iatrogenic complication associated with the procedure; namely, risk of damaging the neurovascular structures of the region (external carotid artery, jugular vein, linguofacial vein, maxillary vein, hypoglossal nerve, vagosympathetic trunk of the recurrent laryngeal nerve).9–11 The surgical anatomy of transmylohyoid orotracheal intubation is relatively simple compared to the pharyngotomy tracheal intubation approach. When the tongue is retracted away from the mucosal incision, no major vessels or nerves are encountered during the approach. The only named vessel near the approach is the small sublingual artery, which if incised would result in only minor hemorrhage and should be avoided by using blunt dissection through the mylohyoideus muscle. A possible advantage pharyngotomy endotracheal intubation may have over transmylohyoid orotracheal intubation is the ability to convert the pharyngotomy site to a postoperative pharyngostomy feeding tube. However, to avoid epiglottic entrapment, airway obstruction and aspiration pneumonia, the surgical approach needs to be made slightly caudal and dorsal to the joint between the thyroid cartilage and the thyrohyoid bone,12,13 which increases the proximity, and the risk of iatrogenic damage, to the hypoglossal nerve, external jugular vein, lingual artery or external carotid artery.12 In addition, in the management of maxillofacial trauma, postoperative enteral nutritional support is not typically necessary. Thus, the potential risk of the more caudal pharyngotomy approach may outweigh the potential benefit. Because transmylohyoid orotracheal intubation has not been described in domestic animals, there are no published data
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on the success or complication rate. A review of the relevant human literature reveals a low‐complication rate (6.3–7.1%), most of which are minor postoperative skin infections (38–42%).14,15 Postoperative infections did not occur in these 4 dogs. The small number of cases we report prevents drawing any conclusions regarding what effect, if any, antimicrobial drug administration may have had on infection prevention in these dogs or whether antimicrobials are necessary for this procedure. Post‐operative mucocele is a rarely reported complication in people.16 Given the proximity of the oral mucosal incision to the sublingual and mandibular salivary ducts it is reasonable to consider this as a possible complication in dogs; however, trauma to the salivary ducts should easily be avoided by maintaining close proximity to the lingual cortex of the mandible while providing contralateral traction of the tongue. In dogs 1 and 2, the skin at the surgical intubation site was sutured and in dogs 3 and 4, the skin was not sutured. In the future, we will continue to leave the surgical site open for drainage rather than suturing it. Surgical time is typically a consideration for any surgical procedure. The average surgical time for transmylohyoid orotracheal intubation in these 4 dogs was 10 minutes, which is similar to the average surgical time reported in people.17 No literature exists evaluating the average surgical time for pharyngotomy endotracheal intubation in dogs; however, in our experience, pharyngotomy endotracheal intubation takes 15–20 minutes. The approach used in dog 4 was the same approach typically used in people, originally described by Altemir.18 Green and Moore19 described a modification of Altemir’s technique. This modification, which, in the dog, requires an 130° turn to place the endotracheal tube through the laryngeal inlet and into the trachea, was used in dogs 1–3. We found this step somewhat cumbersome and in 2 of the 3 dogs required rotating the dog into sternal recumbency for re‐intubation with the transmylohyoid orotracheal tube. Because the approach used in dog 4 does not require extubation and re‐intubation, it may be slightly faster and avoid the possible need to rotate the dog into sternal recumbency. Given the favorable results for these 4 dogs, we believe transmylohyoid orotracheal intubation will prove to be a safe, simple, effective, and practical alternative to pharyngotomy endotracheal intubation in most dogs undergoing management of maxillofacial fractures. Future studies should investigate its usefulness in oral and maxillofacial surgeries other than trauma (i.e., surgical management of oral neoplasia and other invasive pathologies, surgical management of palatal defects, orthodontic assessment, and treatment), evaluate the prevalence of complications relative to other intubation methods that bypass the oral cavity, and investigate methods to assess and improve upon the techniques described here.
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and thoughtful suggestions for improvement of this manuscript. In addition, we thank Dr. Jessica Riehl and Dr. Chad W. Lothamer for their assistance with the surgical procedures and with the literature review.
DISCLOSURE The authors report no financial or other conflicts related to this report.
REFERENCES 1. Boudrieau RJ, Verstraete FJM: Principles of maxillofacial trauma repair, in Verstraete FJM, Lommer MJ (eds): Oral and maxillofacial surgery in dogs and cats. London, UK, Saunders Elsevier, 2012, pp 233–242 2. Smith MM: Pharyngostomy endotracheal tube. J Vet Dent 2004;21:191–194 3. Hartsfield SM, Genfreau CL, Smith CW, et al: Endotracheal intubation by pharyngotomy. J Am Anim Hosp Assoc 1977;13: 71–74 4. Ochs MW, Tucker MR: Management of facial fractures, in Hupp JR, Ellis E III, Tucker MR (eds): Contemporary oral and maxillofacial surgery (ed 5). St. Louis, MO, Mosby Elsevier, 2008, pp 493–518 5. Nicholson I, Baines S: Complications associated with temporary tracheostomy tubes in 42 dogs (1998–2007). J Small Anim Pract 2012;53:108–115 6. Stephens Devalle JM: Successful management of rabbit anesthesia through the use of nasotracheal intubation. J Am Assoc Lab Anim Sci 2009;48:166–170 7. Riebold TW, Engel HN, Grubb TL, et al: Orotracheal and nasotracheal intubation in llamas. J Am Vet Med Assoc 1994;204:779–783 8. Das S, Das TP, Ghosh PS: Complications from submental endotracheal intubation: a prospective study and literature review. J Anesthesiol Clin Pharmacol 2012;28:291–303 9. Evans HE, de Lahunta A: The heart and arteries, in Evans HE, de Lahunta A (eds): Miller’s anatomy of the dog (ed 4). St. Louis, MO, Saunders Elsevier, 1993, pp 428–504 10. Evans HE, de Lahunta A: Veins, in Evans HE, de Lahunta A (eds): Miller’s anatomy of the dog (ed 4). St. Louis, MO, Saunders Elsevier, 1993, pp 505–534 11. Evans HE, de Lahunta A: Cranial nerves, in Evans HE, de Lahunta A (eds): Miller’s anatomy of the dog (ed 4). St. Louis, MO, Saunders Elsevier, 1993, pp 708–730
ACKNOWLEDGMENTS
12. Crowe DT, Downs MO: Pharyngostomy complications in dogs and cats and recommended technical modifications: experimental and clinical investigations. J Am Anim Hosp Assoc 1986;22: 493–503
We thank Dr. Lesley Smith, DVM, MS, Diplomate ACVAA, and Dr. Dale E. Bjorling, DVM, MS, Diplomate ACVS, for their review
13. Lantz G: Pharyngotomy and pharyngostomy, in Verstraete FJM, Lommer MJ (eds): Oral and maxillofacial surger in dogs and cats. London, UK, Saunders Elsevier, 2012, pp 543–546
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14. Jundt JS, Cattano D, Hagberg CA, et al: Submental Intubation: a review. Int J Oral Maxillofac Surg 2012;41:46–54 15. de Toledo GL, Bueno SC, Mesquita RA, et al: Complications from submental endotracheal intubation: a prospective study and literature review. Dent Traumatol 2013;29:197–202 16. Stranc MF, Skoracki R: A complication of submandibular intubation in a panfacial fracture patient. J Maxillofac Surg 2001;29:174–176
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17. Lima SM Jr, Asprino L, Moreira RW, et al: A retrospective analysis of submental intubation in maxillofacial trauma patients. J Oral Maxillofac Surg 2011;69:2001– 2005 18. Altemir FH: The submental route for endotracheal intubation. A new technique. J Maxillofac Surg 1986;14:64–65 19. Green JD, Moore UJ: A modification of sub‐mental intubation. Br J Anaesth 1996;77:789–791.
Veterinary Surgery 44 (2015) 432–436 © Copyright 2014 by The American College of Veterinary Surgeons
Corresponding Author Jason W. Soukup, DVM, Diplomate AVDC, Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin‐Madison, 2015 Linden Drive, Madison, WI 53706. E‐mail: [email protected]. Submitted July 2013 Accepted November 2013 DOI:10.1111/j.1532-950X.2013.12138.x
Objective: To describe the surgical technique of transmylohyoid orotracheal intubation in surgical management of maxillofacial fractures in dogs. Study Design: Case series. Animals: Dogs (n ¼ 4) with maxillofacial fractures. Methods: Transmylohyoid orotracheal intubation was used for airway management of dogs undergoing surgical repair of maxillofacial trauma. A stoma was surgically created by an incision through the skin, subcutaneous tissue, and mylohyoideus muscle immediately medial to the lingual cortex of the mandible at the level of the mandibular 1st molar tooth, so that an endotracheal tube could exit the oral cavity between the mandibular bodies bypassing the dentition. Results: Transmylohyoid orotracheal intubation allowed excellent surgical visibility of the oral cavity and intraoperative control of occlusion during surgery. No complications were encountered during the procedure and the stoma healed without complication. Conclusions: Transmylohyoid orotracheal intubation is a safe, simple, and effective technique for bypassing the rostral oral cavity and dentition during surgical management of maxillofacial fractures.
Simultaneous return of proper occlusion and fracture reduction is the primary objective of maxillofacial fracture repair.1 To achieve this objective, intraoperative control of occlusion, by bypassing the dentition, must be obtained. In dogs and cats, this has typically been achieved by using pharyngotomy endotracheal intubation.2,3 However, because of the complex neurovascular anatomy at the pharyngotomy site, this procedure inherently carries a potential risk of iatrogenic complications. We report our experience using a novel alternative approach, transmylohyoid orotracheal intubation that minimizes these risks, in 4 dogs undergoing maxillofacial fracture repair.
MATERIALS AND METHODS Surgical Technique The airway was secured by orotracheal intubation immediately after induction of general anesthesia. Dogs were positioned in dorsal recumbency and the skin on the ventral aspect of the mandible was clipped and aseptically prepared for surgery. An incision with a length approximating the diameter of the endotracheal tube to be used was made through the skin and subcutaneous tissues immediately medial to the ventral border of the mandible at the level of the mandibular 1st molar tooth (Fig 1A and B). While maintaining contact with the lingual
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cortex of the mandible, blunt dissection was performed dorsally through the subcutaneous tissues and mylohyoideus muscle using a combination of Metzenbaum scissors and hemostats (Fig 1C). An intraoral incision was then made in the mucosa overlying an inserted hemostat tip immediately lingual and ventral to the mucogingival junction of the lingual mucosa of the mandibular 1st molar tooth (Fig 1D) and the resulting tunnel widened as needed to accommodate a reinforced cuffed endotracheal tube. In dogs 1–3, a large forceps (i.e., Carmalt) was inserted through the natural orifice into the oral cavity, through the oral mucosal incision to exit the oral cavity through the ventral skin incision, and used to grasp the cuffed end of the reinforced transmylohyoid orotracheal tube (Fig 1E), which was pulled into the oral cavity (Fig 1F). The initial orotracheal tube was removed from the trachea and the transmylohyoid orotracheal tube was retroflexed and guided through the laryngeal inlet and into the trachea (Fig 1G). Alternatively, as in dog 4, the non‐cuffed end of the traditionally placed endotracheal tube can be pulled through the stoma to exit the oral cavity. In dog 4, the cuff balloon of the endotracheal tube was passed from the oral cavity through the stoma (Fig 2A), then a Carmalt forceps was inserted through the stoma into the oral cavity and used to grasp the non‐cuffed end of the traditionally placed reinforced endotracheal tube (Fig 2B), which was then pulled through the stoma (Fig 2C).
Veterinary Surgery 44 (2015) 432–436 © Copyright 2014 by The American College of Veterinary Surgeons
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Transmylohyoid Orotracheal Intubation
Clinical Report
Figure 1 Photograph of a cadaver demonstrating transmylohyoid orotracheal intubation. (A) Location of the skin incision at the level of the mandibular 1st molar tooth; (B) ventral cortex of the mandible (þ) and the mylohyoideus muscle ( ); (C) blunt dissection through the fibers of the mylohyoideus muscle; (D) mucosal incision over a hemostat inserted through the extraoral surgical approach; (E) Carmalt forceps inserted through the surgical stoma from the oral cavity to grasp the cuffed end of the reinforced endotracheal tube; (F) reinforced endotracheal tube being pulled through the surgical stoma and into the oral cavity; (G) transmylohyoid orotracheal tube being retroflexed and inserted into the trachea to complete the transmylohyoid orotracheal intubation.
The transmylohyoid orotracheal tube was connected to the anesthetic circuit and secured to the dog according to clinician preference. At the end of the procedure, the transmylohyoid orotracheal tube was removed through the incision and the dog re‐intubated by the orotracheal method for recovery or any additional procedures. In dogs 1 and 2, the surgical site was closed. Subcutaneous tissues and the mylohyoideus muscle were closed with a 4‐0 synthetic absorbable suture in a simple continuous pattern. The ventral skin incision was sutured with a 4‐0 synthetic non‐absorbable suture in a simple interrupted pattern and the oral mucosal incision left to heal by second intention. In dogs 3 and 4, the entire surgical site was left to heal by second intention.
Four dogs (Siberian Husky, Australian Shepherd, Irish Terrier, Yorkshire Terrier; 3 females [1 intact, 2 spayed] and 1 intact male) requiring mandibular fracture management were recruited for this study. Mean dog’s age was 30.6 months (range, 2.5–108 months) and mean weight, 9.4 kg (range, 3.41–17.5 kg). Maxillofacial trauma was either from altercation with another dog (dogs 1, 3, and 4) or altercation with a cow (dog 2). Preoperative hematologic and serum biochemical profile findings were unremarkable. All dogs had preoperative CT for diagnosis and surgical planning. Imaging findings were a transverse, mildly displaced, left (dogs 1, 3), right (dog 4) or bilateral (dog 2) mandibular fracture. The fracture was comminuted in dogs 1 and 3. Dog 1 also had a mildly displaced, comminuted left maxillary fracture and a ventrally luxated left nasal bone. Fractures were located at the level of the 1st molar (dogs 1, 4), 1st premolar (dog 2) and junction of the mandibular body and mandibular ramus (dog 3). Typical time to perform transmylohyoid orotracheal intubation was 10 minutes. Dogs were treated in dorsal recumbency and intraoperative control of occlusion was achieved by tying roll gauze around the upper and lower jaw just caudal to the canine teeth (dog 1), by securing a fiber‐ reinforced, bondable reinforcement dental ribbon to the buccal surface of each tooth from the left mandibular 1st molar tooth to the right mandibular 1st molar tooth with a flowable, light curable dental composite (dog 2) or by securing the transmylohyoid orotracheal tube tie around the dogs upper and lower jaws (dog 3). The method of fracture fixation (interdental wire and interdental acrylic splint) prevented the upper and lower jaws to be fixed in occlusion in dog 4. The mandibular fractures were managed either with wire osteosynthesis, interdental wiring, intraoral acrylic splinting or a combination thereof. In dog 2, the intraoral acrylic splint was reinforced with a K‐wire. To reduce the luxated left nasal bone in dog 1, a periosteal elevator was inserted into the left nasal cavity and dorsal attraction was applied. The non‐ displaced maxillary fracture was not treated. Postoperative occlusion was assessed and determined to be normal in all 4 dogs. After completion of fracture reduction, the transmylohyoid orotracheal intubation tube was removed and all dogs were re‐intubated by an orotracheal approach for recovery. Three dogs (dogs 1, 2, and 4) were administered systemic antimicrobials to prevent infection of an open fracture site. Dogs 2 and 4 had oral chlorhexidine rinses to minimize biofilm buildup on the interdental splint. Pre‐/intraoperative pain control consisted of bupivacaine regional anesthesia (dogs 1– 4), subcutaneous meloxicam injection (dog 3), IV fentanyl/ lidocaine/ketamine continuous rate infusion (CRI) (dogs 2 and 4), IV morphine/lidocaine/ketamine CRI (dog 1) and IV fentanyl CRI (dog 3). Postoperative pain control consisted of IV CRI of fentanyl (dogs 2–4) or morphine/lidocaine/ketamine (dog 1), transdermal fentanyl (dogs 2–4), oral carprofen (dogs 1 and 2), oral acetaminophen (dog 4), and oral tramadol (dogs 1–4). No complications related to the transmylohyoid
Veterinary Surgery 44 (2015) 432–436 © Copyright 2014 by The American College of Veterinary Surgeons
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Figure 2 Photograph of a cadaver demonstrating repositioning a conventional reinforced orotracheal tube through a transmylohyoid approach. (A) The orotracheal tube cuff balloon is being pulled from the oral cavity through the surgical stoma; (B) the rostral end of the orotracheal tube is being grasped by a Carmalt forceps inserted through the surgical stoma and is retroflexed, and (C) withdrawn through the stoma to exit the oral cavity. Note that the tube connection port has been removed to facilitate transportation of the tube through the surgical approach.
orotracheal intubation surgical site were seen immediately postoperatively or at a 2‐week follow‐up in any of the dogs. All dogs had fracture healing with normal occlusion.
DISCUSSION There are few clinical scenarios in which bypassing the dentition during endotracheal intubation is as vital to clinical success as in the management of maxillofacial fractures. Simply achieving interdigitation of the fracture segments without intraoperative control of occlusion is of little long‐term benefit to the patient with maxillofacial fractures. Not only will the patient suffer from chronic malocclusion and its secondary complications (pain, dental trauma, and periodontal disease), the resultant abnormal tooth‐to‐tooth contact will impart abnormal forces on the healing fracture and may increase the chance of a non‐ or mal‐union.1 By controlling occlusion during fracture fixation, the clinician helps to ensure that the bone fragments are correctly aligned and provides the best possible long‐term outcome.4 The endotracheal tube must bypass the dentition and, therefore, cannot enter the oral cavity through the natural orifice. Several methods for bypassing the oral cavity have been described. Tracheotomy achieves the necessary bypass, but may have potential morbidity.5 Although not anatomically possible in dogs and cats, nasotracheal intubation has been used when the orotracheal method is not possible in rabbits and llamas6,7 and is the standard method of intubation in people who do not have either a nasal‐orbital‐ethmoid fracture or a skull base fracture.8 Pharyngotomy endotracheal intubation would have allowed for similar intraoperative control of occlusion and likely would have achieved the same result in all 4 dogs; however, transmylohyoid orotracheal intubation achieved the surgical principles of maxillofacial fracture repair with the benefit of (1) shorter surgery time, (2) a simpler surgical approach, and (3) lower inherent risk of iatrogenic
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complications. Transmylohyoid orotracheal intubation was successfully used in a dog of bilateral rostral mandibular fractures. In dogs of bilateral caudal mandibular fractures, pharyngotomy endotracheal intubation may be preferred over transmylohyoid orotracheal intubation. Although we could not find published data reporting the complication rate or nature of pharyngotomy endotracheal intubation, anatomic familiarity and clinical experience suggests there is an inherent, and potentially serious, risk of iatrogenic complication associated with the procedure; namely, risk of damaging the neurovascular structures of the region (external carotid artery, jugular vein, linguofacial vein, maxillary vein, hypoglossal nerve, vagosympathetic trunk of the recurrent laryngeal nerve).9–11 The surgical anatomy of transmylohyoid orotracheal intubation is relatively simple compared to the pharyngotomy tracheal intubation approach. When the tongue is retracted away from the mucosal incision, no major vessels or nerves are encountered during the approach. The only named vessel near the approach is the small sublingual artery, which if incised would result in only minor hemorrhage and should be avoided by using blunt dissection through the mylohyoideus muscle. A possible advantage pharyngotomy endotracheal intubation may have over transmylohyoid orotracheal intubation is the ability to convert the pharyngotomy site to a postoperative pharyngostomy feeding tube. However, to avoid epiglottic entrapment, airway obstruction and aspiration pneumonia, the surgical approach needs to be made slightly caudal and dorsal to the joint between the thyroid cartilage and the thyrohyoid bone,12,13 which increases the proximity, and the risk of iatrogenic damage, to the hypoglossal nerve, external jugular vein, lingual artery or external carotid artery.12 In addition, in the management of maxillofacial trauma, postoperative enteral nutritional support is not typically necessary. Thus, the potential risk of the more caudal pharyngotomy approach may outweigh the potential benefit. Because transmylohyoid orotracheal intubation has not been described in domestic animals, there are no published data
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on the success or complication rate. A review of the relevant human literature reveals a low‐complication rate (6.3–7.1%), most of which are minor postoperative skin infections (38–42%).14,15 Postoperative infections did not occur in these 4 dogs. The small number of cases we report prevents drawing any conclusions regarding what effect, if any, antimicrobial drug administration may have had on infection prevention in these dogs or whether antimicrobials are necessary for this procedure. Post‐operative mucocele is a rarely reported complication in people.16 Given the proximity of the oral mucosal incision to the sublingual and mandibular salivary ducts it is reasonable to consider this as a possible complication in dogs; however, trauma to the salivary ducts should easily be avoided by maintaining close proximity to the lingual cortex of the mandible while providing contralateral traction of the tongue. In dogs 1 and 2, the skin at the surgical intubation site was sutured and in dogs 3 and 4, the skin was not sutured. In the future, we will continue to leave the surgical site open for drainage rather than suturing it. Surgical time is typically a consideration for any surgical procedure. The average surgical time for transmylohyoid orotracheal intubation in these 4 dogs was 10 minutes, which is similar to the average surgical time reported in people.17 No literature exists evaluating the average surgical time for pharyngotomy endotracheal intubation in dogs; however, in our experience, pharyngotomy endotracheal intubation takes 15–20 minutes. The approach used in dog 4 was the same approach typically used in people, originally described by Altemir.18 Green and Moore19 described a modification of Altemir’s technique. This modification, which, in the dog, requires an 130° turn to place the endotracheal tube through the laryngeal inlet and into the trachea, was used in dogs 1–3. We found this step somewhat cumbersome and in 2 of the 3 dogs required rotating the dog into sternal recumbency for re‐intubation with the transmylohyoid orotracheal tube. Because the approach used in dog 4 does not require extubation and re‐intubation, it may be slightly faster and avoid the possible need to rotate the dog into sternal recumbency. Given the favorable results for these 4 dogs, we believe transmylohyoid orotracheal intubation will prove to be a safe, simple, effective, and practical alternative to pharyngotomy endotracheal intubation in most dogs undergoing management of maxillofacial fractures. Future studies should investigate its usefulness in oral and maxillofacial surgeries other than trauma (i.e., surgical management of oral neoplasia and other invasive pathologies, surgical management of palatal defects, orthodontic assessment, and treatment), evaluate the prevalence of complications relative to other intubation methods that bypass the oral cavity, and investigate methods to assess and improve upon the techniques described here.
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and thoughtful suggestions for improvement of this manuscript. In addition, we thank Dr. Jessica Riehl and Dr. Chad W. Lothamer for their assistance with the surgical procedures and with the literature review.
DISCLOSURE The authors report no financial or other conflicts related to this report.
REFERENCES 1. Boudrieau RJ, Verstraete FJM: Principles of maxillofacial trauma repair, in Verstraete FJM, Lommer MJ (eds): Oral and maxillofacial surgery in dogs and cats. London, UK, Saunders Elsevier, 2012, pp 233–242 2. Smith MM: Pharyngostomy endotracheal tube. J Vet Dent 2004;21:191–194 3. Hartsfield SM, Genfreau CL, Smith CW, et al: Endotracheal intubation by pharyngotomy. J Am Anim Hosp Assoc 1977;13: 71–74 4. Ochs MW, Tucker MR: Management of facial fractures, in Hupp JR, Ellis E III, Tucker MR (eds): Contemporary oral and maxillofacial surgery (ed 5). St. Louis, MO, Mosby Elsevier, 2008, pp 493–518 5. Nicholson I, Baines S: Complications associated with temporary tracheostomy tubes in 42 dogs (1998–2007). J Small Anim Pract 2012;53:108–115 6. Stephens Devalle JM: Successful management of rabbit anesthesia through the use of nasotracheal intubation. J Am Assoc Lab Anim Sci 2009;48:166–170 7. Riebold TW, Engel HN, Grubb TL, et al: Orotracheal and nasotracheal intubation in llamas. J Am Vet Med Assoc 1994;204:779–783 8. Das S, Das TP, Ghosh PS: Complications from submental endotracheal intubation: a prospective study and literature review. J Anesthesiol Clin Pharmacol 2012;28:291–303 9. Evans HE, de Lahunta A: The heart and arteries, in Evans HE, de Lahunta A (eds): Miller’s anatomy of the dog (ed 4). St. Louis, MO, Saunders Elsevier, 1993, pp 428–504 10. Evans HE, de Lahunta A: Veins, in Evans HE, de Lahunta A (eds): Miller’s anatomy of the dog (ed 4). St. Louis, MO, Saunders Elsevier, 1993, pp 505–534 11. Evans HE, de Lahunta A: Cranial nerves, in Evans HE, de Lahunta A (eds): Miller’s anatomy of the dog (ed 4). St. Louis, MO, Saunders Elsevier, 1993, pp 708–730
ACKNOWLEDGMENTS
12. Crowe DT, Downs MO: Pharyngostomy complications in dogs and cats and recommended technical modifications: experimental and clinical investigations. J Am Anim Hosp Assoc 1986;22: 493–503
We thank Dr. Lesley Smith, DVM, MS, Diplomate ACVAA, and Dr. Dale E. Bjorling, DVM, MS, Diplomate ACVS, for their review
13. Lantz G: Pharyngotomy and pharyngostomy, in Verstraete FJM, Lommer MJ (eds): Oral and maxillofacial surger in dogs and cats. London, UK, Saunders Elsevier, 2012, pp 543–546
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14. Jundt JS, Cattano D, Hagberg CA, et al: Submental Intubation: a review. Int J Oral Maxillofac Surg 2012;41:46–54 15. de Toledo GL, Bueno SC, Mesquita RA, et al: Complications from submental endotracheal intubation: a prospective study and literature review. Dent Traumatol 2013;29:197–202 16. Stranc MF, Skoracki R: A complication of submandibular intubation in a panfacial fracture patient. J Maxillofac Surg 2001;29:174–176
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17. Lima SM Jr, Asprino L, Moreira RW, et al: A retrospective analysis of submental intubation in maxillofacial trauma patients. J Oral Maxillofac Surg 2011;69:2001– 2005 18. Altemir FH: The submental route for endotracheal intubation. A new technique. J Maxillofac Surg 1986;14:64–65 19. Green JD, Moore UJ: A modification of sub‐mental intubation. Br J Anaesth 1996;77:789–791.
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