Oesophagous Flashcards
Four layers of the equine oesophagus
1) Fiborous tunica adventitia
2) Tunica muscularis
3) Submucosa
4) Mucosa
Forms 2 distinct layers surgically, mucosa/submucosa & muscularis/adventitia
Proportions of skeletal vs smooth muscle
Upper section is skeletal/striated mm - from the pharynx to the heart base
Smooth muscle from heart base caudally - adopts an outer longitudinal and inner circular smooth muscle orientation
Oesophageal blood supply
Cervical from the carotid arteries.
The thoracic & relatively short (2–3 cm) abdominal oesophagus is supplied by the bronchoesophageal and gastric arteries.
The vascular pattern is arcuate but segmental, without generous collateral circulation, necessitating careful preservation of vessels during surgery.
Oesophageal innervation
CN IX and X, sympathetic trunk and mesenteric ganglion within the muscularis
Types of oesophageal stricture
Type 1: Adventitia and muscularis
Type 2: Mucosa and submucosa
Type 3: All layers
Methods of contrast oesophagography
BY MOUTH: Barium liquid is ok (mixed with feed) but paste is preferable (85% wt/vol w water 120ml) given by mouth for +ve contrast; outlines mucosal folds. Avoid sedation - will reduce swallow reflex. Bolus becomes coated and complete obstruction halts barium.
BY NGT: Liquid: 72%wt/vol w 480ml water; To assess strictures/ stenosis, a cuffed NGT can be used with double contrast (liquid barium & air 480ml of each)- in this case xylazine can be helpful to reduce swallowing due to luminal distension.
-ve contrast: via endoscopic insufflation or NGT. Not very useful for caudal cervical/thoracic issues. Act of swallowing may mimic stricture with only air. Sedation can mimic megaoesophagus for as long as 30mins post Dom admin.
3 surgical approaches to the oesophagus
1) Ventral approach. Best used for cervical oesophagotomy, oesophagomyotomy & resections of proximal 1/3. Ventral or ventrolateral for placement of mid-cervical feeding tube placement (oesophagostomy) & approaching distal ¼ of cervical oesophagus. Standing or GA in dorsal. 10cm (=6cm oesophageal exposure) skin incision on midline. Separate paired sternothyroid, sternohyoid, and omohyoid muscles along midline to expose trach. Blunt exploration of fascia along left side of the trachea to expose the oesophagus w NGT in. Trach retracted to right. Provides good ventral drainage.
2) Ventrolateral approach: Useful for mid-cervical feeding tube placement (oesophagostomy: permits anchorage to the skin & prevents impingement on trach). Also provides good access to middle & distal cervical oesophagus where ventral musculature is more well developed. Standing or GA Dorsal or R lateral; 5cm skin incision (for feeding tube) immediately ventral to jugular v. Sternocephalicus & brachiocephalicus mm. are separated, followed by incision of deep fascia. May also need to incise cutaneous colli m. Good approach for feeding tube.
3) Approach to thoracic oesophagus: Thoracotomy req. for access to the thoracic trachea in adults. Foals - rib retraction may suffice. eg for vascular ring anomalies. GA RLR w PPV essential. Skin, SQ, cutaneous trunci, serratus ventralis & latissimus dorsi mm. are incised. Usually performed in foals for vascular ring anomalies (no need to enter oesophageal lumen)- generally don’t need rib resection. Sites used include left 4th, right 5th ICS & also left 8th ICS. Sub-periosteal rib resection necessary in adults, not necessarily foals (retractors).
Indications & technique of oesphagotomy
- Used for retrieval of FB/removal of refractory obstructions
- GA dorsal or RLR - ventral approach for cranial/mid cervical, ventrolateral for caudal cervical
- Longitudinal/vertical full thickness incision into oesophagus; exact location depends on FB mobility, can incise cranial, caudal or directly over FB
- Closure or heal by 2nd intention
- 2 layer closure; mucosa/submucosa separately (if viable), w 3-0 simple continuous monofilament absorbable, ideally knots tied in the lumen (slough in 60 d).
- Close muscle layer - SI 3-0 absorbable sutures
- Routine SQ, skin closure
- If not viable, use aboral oesophagostomy tube
Procedure for oesophagostomy tube placement
- Preferably use ventrolateral approach (ventral also appropriate).
- Ventral - 6cm midline incision at level of C5, through cutaneous colli mm & between paired sternocephalicus mm
- Ventrolateral - 6cm incision ventral to jugular (usually on the left, occasionally right).
- Swallowing/coughing can be decreased by spraying the area w lido
- 1cm incision through oesophageal adventitia & muscularis
- Mucosa grasped & everted & a transverse incision through half width of everted mucosa.
- Remove NGT & place feeding tube (polyethylene w outer diameter of 14-24mm).
- Place in stomach or will dislodge & must be placed (easily) through all layers of oesophagus.
- Can suture mucosa around the tube to improve seal, but won’t stop leakage of saliva.
- Secure to skin w sutures & bandage.
- Treat like indwelling NGT (flush w water & bung when not in use).
- Keep in place for minimum of 7-10 d to develop granulation tissue & allow stoma to form (AMs required until this time).
- Will close secondarily once pulled.
Treatment options for oesophageal strictures
Conservative - bouginage (increasing dietary particle size)
Endoscopic balloon dilation
Oesophagomyotomy (type 1 - outer layers only)
Partial or complete resection
Patch grafting
Describe the procedure for oesophagomyotomy
- Ventral approach
- Longitudinal oesophageal incision through external layers of adventitia & muscularis (down to mucosa or submucisa) over length of stricture & 1cm above & below.
- Now pass NGT past stenotic area.
- Dissect muscularis free from mucosa around entire circumference to release stricture.
- Removal of portion of muscularis or multiple myotomy incisions is rarely necessary.
- If mucosa accidentally opened, close immediately with 3-0 monofilamant absorbables.
- Myotomy incision is NOT CLOSED. Close approach incision routinely.
- Initially frequent small feeds PO; feed as normal once prestenotic dilation resolves.
Describe partial resection procedure and main indications
- Used for strictures with mucosal involvement (type2/3), where myotomy alone does not allow passage of NGT past the stricture.
- Partial resection: = longitudinal myotomy w mucosal resection.
- Initial procedure as per oesophagomyotomy
- Incise mucosa longitudinally to ID abnormal section.
- Then circumfrential incision proximal & distal to affected mucosa & section removed, leaving muscular tube intact.
- If no tension, appose mucosal layer (3x 1/3 circumferential simple continuous w knots in lumen if poss).
- Then close muscularis ONLY if healthy, DO NOT suture is involved in stenosis.
- If mucosa can’t be sutured (extensive stricture) then it can be left & will regenerate.
- Routine closure, drain adjacent.
- Ideal to have OGT aborally, but if too distal to allow this, can place the tube directly through the sx site/site of the stricture - will rx in traction diverticulum & may incr diameter
Indications and steps for oesophageal R&A
- Used for rupture, when muscularis NOT viable.
- Use penrose drain to occlude lumen, as per SI, leaving a border of viable tissue, don’t use clamps
- Sharp transection orally/aborally through healthy tissue either side, excise segment.
- Appose mucosa/submuc. w 3-0 monofilament SI sutures tied in the lumen, 3cm(!-mm?) from cut edge & 2-3mm apart.
- Muscularis closed w absorbable 2-0 SI sutures (may req relief incision to close - circular myotomy 4-5cm proximal & distal to anastomosis to relieve tension).
- Remainder of incision closed routinely.
PO management for oesophageal R&A
PO management very important: use standing martingale to prevent neck extension.
Can feed PO from 48hrs using soft feed until healed. Oesophagostomy tube is preferable.
Indications for and technique for patch grafting
- For extensive annular stricture of all layers
- GA vental/ ventolateral approach depending on defect location.
- Can use brachiocephalicus or sternocephalicus as donor mm for graft.
- Oesophageal muscularis is longitudinally incised 3cm either side of stricture.
- For type 1: suturing muscularis to sternocephalicus mm has been used to create a diverticulum, w decreased chance of stricture formation.
- For type 2 & 3, incise mucosa and subm.
- A caudal portion of brachiocephalicus or sternocephalicus is mobilised; “graft,” should maintain its proximal & distal attachments & needs to be freely movable so not to exert tension on closure when patient’s head & neck are moved. It should be wide enough to appreciably increase lumen of the oesophagus.
- Suture mucosa & subm layer to graft w 3-0 monofilament interrupted sutures in through & through mattress pattern.
- Muscularis sutured to graft w 3-0 SI monofilament sutures.
- Place drains & close as normal. 6-10 days AM
- Extraoral feeding preferable for 10 d PO, ideally oesophagostomy if enough space.
- Can feed PO as soon as 48hrs if saliva not leaking. NGT promotes salivation, which is deleterious to wound healing & promotes fistula formation
2 types of oesophageal diverticulum
1) Traction/true diverticulum: following healing of peri-oesphageal injury; contraction of scar tissue rx in outward traction & tenting of all layers of the oesophageal wall. Usually wide opening & rarely req tx
2) Pulsion/false diverticulum - protrusion of mucosa through a muscularis defect. Propensity to rupture so should be tx w sx
Surgical treatment options for oesophageal diverticula
- Diverticulectomy - resection of mucosal/submucosal sac followed by reconstruction of the mucosa/submucosa/muscularis
- Mucosal inversion (preferred option; avoids penetration of lumen):
- Diverticulum & defect in muscularis identified
- Debride edges of muscularis to healthy tissue (accidental mucosal penetration should be repaired immediately)
- Invert the mucosa/ subm sac into lumen & close muscularis defect w SI 3-0 polypropelene sutures w minimal tension.
- Close incision as normal. Soft foods 4-6 weeks
