Complications in Equine Surgery. Группа авторов

and readers are directed to that chapter.

       Expected outcome

      In the cases described in the literature, and as described in Chapter 3, horses would be expected to recover and return to normal from this complication if recognized and insufflation was stopped. The horse described in Gordon et al. [5] was euthanized following recovery from two occurrences of presumptive vascular air embolism, due to a poor prognosis for a malignant lesion that prompted the cystoscopy.

References

      1 1 Sykes, B.W. and Jokisalo, J.M. (2014). Rethinking equine gastric ulcer syndrome. Part 1: Terminology, clinical signs and diagnosis. Equine Vet. Educ. 26: 543–547.

      2 2 Bonilla, A.G., Hurcombe, S.D., Sweeney, R.W. et al. (2014). Small intestinal segmental volvulus in horses after gastroscopy: four cases (2011–2012). Equine Vet. Educ. 26: 141–145.

      3 3 Kilcoyne, I. and Dechant, J.E. (2014). Complications associated with perineal urethrotomy in 27 equids. Vet. Surg. 43: 691–696.

      4 4 Wurm Johansson, G., Nemeth, A., Nielsen, J. et al. (2013). Gastric rupture as a rare complication in diagnostic upper gastrointestinal endoscopy. Endoscopy. 45: E391.

      5 5 Gordon, E., Schlipf, J.W., Husby, K.A. et al. (2015). Two occurrences of presumptive venous air embolism in a gelding during cystoscopy and perineal urethrotomy. Equine Vet. Educ. doi: 10.1111/eve.12507.

      6 6 Romagnoli, N., Rinnovati, R., Lukacs, R.M. et al. (2014). Suspected venous air embolism during urinary tract endoscopy in a standing horse. Equine Vet. Educ. 26: 134–137.

      7 7 Nolen‐Walston, R. (2014). Venous air embolism during cystoscopy in standing horses. Equine Vet. Educ. 26: 138–140.

5 Complications of Nasogastric Intubation

       Julie E. Dechant DVM, MS, DACVS, DACVECC

       School of Veterinary Medicine, University of California–Davis, Davis, California

Overview

      Nasogastric intubation is performed to check for gastric reflux, relieve gastric distension, or administer enteral fluids, laxatives, or medications. Nasogastric intubation is achieved by directing and maintaining the nasogastric tube into the ventral meatus of the nasal cavity, without traumatizing the nasal turbinates and the ethmoid turbinates. The tube is blindly manipulated within the nasopharynx to the esophageal opening, avoiding the dorsal pharyngeal recess and the salpingopharyngeal plica. Once in the esophagus, the nasogastric tube is gently advanced aborally to enter the cardia of the stomach.

      The blind manipulation and passage of the tube can result in trauma to the associated tissues along the intended pathway, and trauma to structures if the tube is misdirected. Misplacement of the tube can result in further problems (fragmentation of the tube or administration of fluid into the lungs) if not recognized.

List of Complications Associated with Nasogastric Intubation

       Epistaxis

       Misplacement of tube

       Esophageal/pharyngeal trauma

       Fragmentation of tube

       Administration of fluid into lungs

       Sinusitis

Epistaxis

       Definition

      Epistaxis is the presence of hemorrhage from the nares.

       Risk factors

       Inexperience, although hemorrhage may occur with skillful intubation in a compliant horse

       Non‐compliant horse

       Pathogenesis

      Epistaxis is the most common complication from nasogastric intubation [1–3]. Hemorrhage can occur when the respiratory mucosa, nasal turbinates, or ethmoid turbinates are traumatized.

       Prevention

      The risk of epistaxis may be minimized by careful and gentle technique and assuring advancement of tube into ventral nasal meatus using well‐lubricated tubes that are in good condition and free of external defects or roughening. Tube diameter should be selected to be an appropriate size for the patient, with the dimensions of the ventral nasal meatus being most limiting. Although water often provides sufficient lubrication in most circumstances, additional lubrication using carboxymethylcellulose or lubricating gel at the end of the tube may reduce risk of epistaxis in small patients, patients with dry or friable mucosa, or animals with restricted nasal passages. Pre‐emptive intranasal application of phenylephrine spray, which causes local vasoconstriction of vessels within the nasal mucosa, may be of benefit. Patients should be adequately restrained, which may require use of a nose twitch or sedation.

       Diagnosis

      Epistaxis occurs during placement or immediately after removing the nasogastric tube.

       Treatment

      Mild elevation of the head may speed resolution of bleeding, because lowering the head increases venous congestion, which would delay hemostasis. Extreme elevation of the head should be avoided because it increases the risk of aspiration and pneumonia [1]. Packing of the affected nasal cavity is an option, but the technique may simply divert hemorrhage into the nasopharynx and not reduce the volume of bleeding. Intranasal application of phenylephrine or epinephrine may be useful in providing local vasoconstriction; however, ongoing bleeding may limit the amount and distribution of drug that is absorbed by the nasal mucosa.

       Expected outcome

      Bleeding may be minor or more significant, and is usually self‐limiting [2]. In rare circumstances, hemorrhage may be severe enough to require blood transfusion and the administration of drugs to promote coagulation and prevent fibrinolysis. It is recommended that horses should not be anesthetized while there is ongoing nasal hemorrhage, because the head is generally positioned lower than the heart during anesthesia, which would exacerbate hemorrhage, and the cardiovascular consequence of ongoing blood loss is less tolerated during the cardiovascular depressant effects of most anesthetic drugs.

Misplacement of Tube

       Definition

      The tube is inadvertently misdirected into tracheal lumen, guttural pouch or retroflexes at the back of the nasopharynx and enters the oral cavity, or exits out the contralateral nostril while advancing the tube.

Risk factors

       Uncooperative patients, inadequate restraint or assistance, and inexperience with the procedure are predominant risk factors.

       Excessively pliable nasogastric tubes increase the risk of misplacement or misdirection of the tube.

       Smaller diameter tubes may increase the risk of misplacement of the tube within the guttural pouch (Figure 5.1).

       Pathogenesis

Misplacement of the nasogastric tube is a common complication of nasogastric intubation. The esophageal opening is directly dorsal to the arytenoid cartilages