equine GIT sx 3.pdf

OVERVIEW OF GI LECTURE SERIES [email protected]  Exploratory laparotomy  Anatomy review  Specific surgical approaches  Disorders of the GI tract by location Problems Annette McCoy, DVM, MS, PhD, DACVS  Introduction: Colic – what it is (and what it isn’t)  Stomach  Small intestin...

OVERVIEW OF GI LECTURE SERIES [email protected]  Exploratory laparotomy  Anatomy review  Specific surgical approaches  Disorders of the GI tract by location Problems Annette McCoy, DVM, MS, PhD, DACVS  Introduction: Colic – what it is (and what it isn’t)  Stomach  Small intestine  Cecum  Large colon  Small colon 10/30  By the end of this session, the learner will be able to: 1. Identify factors that go into the decision for taking a horse to surgery for colic; 2. Describe the approach for an exploratory laparotomy and identify the portions of the GI tract that are accessible; 3. Describe basic principles for performing an exploratory laparotomy; 4. Describe factors that determine whether a resection is required or not; 5. Create a reasonable post-operative monitoring and treatment plan; 6. Describe possible short-term and long-term complications associated with specific GI lesions; 7. Describe expected outcomes following surgery for various GI lesions; 8. Identify indications, advantages, and disadvantages, for laparoscopy in the horse.  Small intestine  Large intestine 11/3  Post-operative management  Complications and outcomes after GI surgery  Laparoscopy 11/1  Rectal tears OBJECTIVES: PART 3 Treatments VM654 Fall 2023 Application EQUINE GASTROINTESTINAL SURGERY: PART 3  Clinical Correlations  Colic workup  Case studies 11/8 (2 hr) LESION DISTRIBUTION AMONG REFERRAL POPULATION  30-35% small intestine  60-80% of these are caused by strangulating lesions  5% cecum  40-55% of these are impactions  50-60% large colon  10% small colon  30-40% of these are impactions SURGICAL DECISION-MAKING 1. Pain 2. Suspected strangulating obstruction  Distended small intestine, tight bands, serosanguinous belly tap 3. Lesions not responding to medical management  E.g. nephrosplenic entrapment, right dorsal displacement of the colon, impaction 4. Severe/chronic non-strangulating obstructions  E.g. large impaction, enterolith BEFORE SURGERY  As much preparation/stabilization as possible, while keeping everyone safe  At a minimum, establish vascular access  Jugular catheter, large bore (14g or larger)  Fluids  Hypertonic saline (7.2%) and/or isotonic fluids  Broad-spectrum antibiotics  Analgesia (usually already given)  If the horse has gotten an NSAID within the past 12 hours, don’t give more  Clip and rough prep before induction to reduce anesthesia time EXPLORATORY LAPAROTOMY  Dorsal recumbency, ventral midline incision from umbilicus cranially (30-40cm incision)  Protect the underlying viscera (usually gas distended)  Blunt penetration of peritoneum  Primary problem may or may not be immediately obvious  Palpation of the viscera in place to try to determine where the problem is EXPLORATORY LAPAROTOMY  Relieving gas distention (cecum, colon)can help exteriorize viscera  GENTLE exteriorization of large colon  Generally place onto colon tray between back legs or to the side  Closed hands (no poking fingers), cradle and rock  Colon and cecum are straight relative to each other when the cecocolic ligament is visualized EXPLORATORY LAPAROTOMY  Examine the small intestine systematically WHAT CAN YOU ACCESS?  Can exteriorize: from ileum to duodenum  Jejunum and proximal  Follow ileocecal fold from dorsal band to the  Apex and part of body of cecum to antimesenteric border of the ileum  GENTLE exteriorization – reach into abdomen and bring out, don’t pull from outside the abdomen ileum cecum  ~75% of large colon  Middle portion of small colon  Small colon generally evaluated last  Cannot exteriorize:  Stomach  Duodenum, distal ileum  Base of cecum  Distal right dorsal colon and transverse colon  Proximal and distal small colon  Rectum Some lesions cannot be corrected even with surgery Large colon SURGICAL CORRECTION: SMALL INTESTINE ADHESIONS  Identify the primary lesion – strangulating or non- Small intestinal mesentery strangulating?  Evaluate the health of the bowel – decision to resect or leave in place  Length and location of lesion important factors  Decompress small intestine into the cecum (gas, fluid)  Even gentle handling will result in irritation/petechiation Small colon  Risk of post-op adhesions Pelvic flexure Cecum METHODS FOR EVALUATING BOWEL HEALTH  Clinical assessment  Color of serosa (pink vs deep red to purple)  Color of mucosa (pink vs deep red to purple)  Quality of mucosa (sturdy vs friable)  Motility (amotile vs inducible motility with finger “flick” vs spontaneous motility)  Wall thickness (normal vs edematous)  Health of vasculature (pulse quality, edema in perivascular tissue) METHODS FOR EVALUATING BOWEL HEALTH  Clinical assessment  Color of serosa  Color of mucosa  Quality of mucosa  Motility Hard to interpret; better at predicting survival than nonsurvival  Identify extent of compromised bowel  Make sure you have good blood supply to the ends staying in  Jujunum-jejunum, jejunum-ileum, jejumum-cecum  Decompress oral SI through the cut end  1- or 2-layer closure – careful with inverting patterns  IV fluorescein dye administration  Surface oximetry  Doppler ultrasonography  Histopathology  Wall thickness  Snap frozen intraop interpretation  Health of vasculature  Formalin fixed postop interpretation  Do any of these change after strangulating lesion is corrected? Good predictive  Do they change after replacing bowel in ability, but rarely abdomen for 15-20min? SMALL INTESTINAL RESECTION & ANASTAMOSIS  Ancillary methods available JEJUNOCECOSTOMY  Remove diseased segment, oversew ileal stump  Side-to-side anastomosis between dorsal and medial band, with stump oriented toward base SURGICAL CORRECTION: CECUM Cannot be exteriorized SURGICAL CORRECTION: LARGE COLON  Exteriorize colon – identify displacement or direction of  For cecal impaction non-responsive to medical torsion management, a typhlotomy or cecal bypass may be required  Correct torsion - flat hands, gentle tissue handling  Determine if straight by palpation and by visualization of cecocolic  8-12cm typhlotomy incision between the ventral and ligament lateral cecal bands near the apex  Often need to dump colon contents via pelvic flexure  Manipulation from the base upwards to evacuate ingesta enterotomy  Anastamosis for bypass made the lateral and dorsal  Evaluate health of colon – decision to resect or leave in cecal bands and the lateral and medial free bands of the right ventral colon place (or euthanize if non-resectable) LARGE COLON RESECTION LARGE COLON RESECTION  Side-to-side or end-to-end  Stapled or hand-sewn  Try to take all compromised tissue (can’t always) Cecum If the twist was proximal to this line, can’t remove all compromised tissue Large Colon SURGICAL CORRECTION: SMALL COLON COMPLETION OF SURGERY  Reduction of small colon impactions typically  Replace bowel in normal anatomical position accomplished with intraluminal fluid and gentle extraluminal massage  Enteroliths/fecaliths need to be removed via enterotomy  Go through the antimesenteric band  Resection and anastomosis similar to small intestine  For segmental strangulation - rare  Pelvic flexure towards pelvis  Dorsal colon dorsal, ventral colon ventral  Cecum on the right with apex pointed cranially  Copious lavage of the abdomen with warm saline  Linea closure: 3 Vicryl, simple continuous pattern, 1cm x 1cm bites  Subcutaneous tissue closure: 2-0 Monocryl, simple continuous pattern  Skin: staples or absorbable suture in a simple continuous pattern  Stent or adhesive bandage (Ioban) or for recovery Different surgeons may have different suture preferences POST-OPERATIVE MANAGEMENT POST-OPERATIVE MANAGEMENT  Adhesive bandage often placed after recovery  Intravenous fluids  Leave on 24-72 hours, replace if needed  Analgesia  Flunixin meglumine has anti-endotoxic, anti- inflammatory, and analgesic effects  1.1mg/kg q12h or 0.5mg/kg q8h, 3-7d or as needed depending on case  Antibiotics  Broad spectrum IV (K Pen/Gentamicin)  3-7 days or as needed depending on case  May make decision based on CBC  24 hours for uncomplicated cases, longer if needed  Can add electrolytes as needed based on blood gas results (Ca, Mg, P)  Lidocaine (continuous rate infusion)  Often added to prevent or treat post-operative ileus  Mechanism unknown, possible anti-inflammatory effects, has not been shown to increase motility  Return to feeding depends on surgical findings  For uncomplicated large colon displacement, can start feeding a few hours after recovery  Wait longer for resections, or if refluxing  SMALL amounts FREQUENTLY, then gradually increase the amount and the timing between meals TRANSITION TO HOME  Hospital stay varies depending on underlying cause and response to therapy  24-48 hours for uncomplicated medical colic SHORT-TERM COMPLICATIONS Common Less Common  3-10 days for more complicated medical colic  Colic/pain  4-7 days post-surgery, depending on whether complications develop  Incisional drainage or infection  Generally can have normal feeding once home  Post-operative ileus  8+ weeks before back to work under saddle  Endotoxemia  Jugular thrombophlebitis Most common with small intestinal disease  Septic peritonitis  Colic/diarrhea  Week 1-2: strict stall rest – staples removed at 2 weeks  Week 3-4: stall rest with 10-20min hand-walking daily  Week 5-8: gradually increasing amounts of hand-walking  May be up to 6 months before back in full work LONG-TERM COMPLICATIONS • Repeat laparotomy in ~10% of cases, due to persistent reflux or persistent pain • Risk of complications higher after 2nd procedure EXPECTED OUTCOMES AFTER SURGERY  55-85% of horses taken to surgery are expected to recover from  Most common complication is repeat colic episodes (35%)  Other reported complications: weight loss, ventral hernia  Horses with right dorsal displacement reported to be at higher risk for repeat colic than horses with other non-strangulating displacements anesthesia  Overall, 83% of horses that recover from anesthesia are discharged from the hospital  Overall, 84% of horses that are discharged from the hospital survive for at least a year BUT…different conditions carry different prognoses OUTCOMES FOR SPECIFIC CONDITIONS  Horses with small intestinal lesions (75%) or cecal lesions (67%) are less likely to survive to discharge than those with large colon or small colon lesions (>90%)  Horses with a strangulating obstruction or nonstrangulating infarction (69%) are less likely to survive to discharge than those with a simple obstruction (90%)  Horses with an epiploic foramen entrapment (50%) that survive to discharge are less likely to survive to 1 year than horses with other small intestinal lesions (90%) LAPAROSCOPIC SURGERY  Older horses are equally likely to survive as younger horses if you take the type of lesion into account  BUT, they are more likely to have strangulating small intestinal lesions (which carry a poorer prognosis) LAPAROSCOPY  Minimally invasive diagnostic technique that can be used to evaluate many conditions  Chronic colic  Traumatic injuries after foaling  Puncture wounds into the abdomen  Splenic and liver disease  Adhesions  Abscesses  Can be done standing or with the patient anesthetized and in dorsal recumbancy INSTRUMENTATION INSTRUMENTATION 57cm  Scopes come in a variety of lengths and viewing angles  30-60cm long  0°, 25°, 30° 31cm INSTRUMENTATION  Laparoscopic instruments  Grasping forceps  Scissors  Probes  Cannulas with blunt or sharp trochars  11mm diameter for use with 10mm diameter instruments  Injection cannulas  Biopsy forceps  6mm diameter for use with 5mm diameter instruments  Working length 15-20cm IT TAKES A TEAM… COMMON INDICATIONS FOR LAPAROSCOPY IN HORSES  Abdominal exploratory  Repair of rectal tears  Tissue biopsy  Repair of body wall or inguinal  Cryptorchidectomy  Ovariectomy  Breakdown of adhesions  Colopexy or nephrosplenic space ablation hernias  Epiploic foramen ablation  Hand-assisted procedures  Nephrectomy  Cystotomy Ovariectomy: https://www.youtube.com/watch?v=-9kzBAj_byc Cryptorchidectomy: https://www.youtube.com/watch?v=S6Nqa6kpRMM Will have to sign in to YouTube to confirm your age CONCLUDING THOUGHTS LAPAROSCOPY VS. LAPAROTOMY Advantages  Smaller incisions, minimal post-op wound care  Faster return to work in most cases  Standing procedures eliminate the risk associated with anesthesia Disadvantages  Not appropriate for all procedures  May be able to diagnose, but not fix a problem  Limited visibility compared to laparotomy  Requires specialized equipment and training CONCLUDING THOUGHTS  The most common post-operative complications are recurrent pain/colic and incisional infections/drainage  Pain and post-operative ileus are the most common indications for repeat laparotomy  In general, small intestinal lesions carry a poorer prognosis than large intestinal lesions, however…  If a patient survives to discharge, there is generally good long-term survival regardless of the primary lesion  Laparoscopy offers a minimally invasive diagnostic and therapeutic surgical option for a variety of conditions  Pain is the #1 reason to take a horse to surgery, regardless of the underlying lesion  An exploratory laparotomy provides the best opportunity to identify and correct intestinal lesions  BUT, not all lesions can be fixed, even with surgery  Gentle tissue handling is the most important principle to observe when manipulating bowel to avoid iatrogenic damage  Resection decisions are made based on location and length of affected bowel, as well as the health of the bowel QUESTIONS?