Small Bowel 2 PDF

Surgery II MD 420   Coordinator: Dimitrios Ntourakis MD, PhD, FACS Small bowel Surgery II – MD420 Dimitrios Ntourakis MD, PhD, FACS Objectives Discuss the usual surgical pathologies of the small bowel Understand the causes, pathophysiology and treatment of small bowel obstruction Learn about the s...

Surgery II MD 420   Coordinator: Dimitrios Ntourakis MD, PhD, FACS Small bowel Surgery II – MD420 Dimitrios Ntourakis MD, PhD, FACS Objectives Discuss the usual surgical pathologies of the small bowel Understand the causes, pathophysiology and treatment of small bowel obstruction Learn about the short bowel syndrome and the blind loop syndrome Present the tumors encountered in the small intestine Understand the modalities for endoscopic exploration of the small intestine Anatomy Jejunum Ileum Mesentery + vessels Wall layers Mucosa Submucosa Muscularis (circular, longitudinal) Serosa Physiology – motility Nerve plexi Myenteric plexus of Auerbach (peristalsis) Submucosal plexus of Meissner (secretion) Regulatory peptides Cholecystokinin Vasoactive intestinal peptide (VIP) Somatostatin Enkephalin Neurotensin Substance P The duodenum defines the frequency of pacesetter potential for the small bowel Physiology – motility Propagating and non propagating muscular contractions Interdigestive migrating myoelectric complex (MMC) from duodenum to colon every 1 1/2 to 2 h cleans up meal remnants Is abolished by ingestion of food Mean transit time from mouth to colon = 4h Physiology – absorption Digestion, secretion and absorption 5-9L of fluid/day in the small bowel => 1-2L pass into the colon Vili absorb nutrients, crypts absorb water and electrolytes. Physiology – absorption Substance Break-down Absorption Carbohydrates amylase => monosaccharides active transportation (jejunum and proximal ileum). Protein pancreatic proteases => oligopeptides and aminoacids active absorption (proximal jejunum) Fat lipases => triglyceride hydrolysis= Fatty acids + bike salts -> micelles enter mucosal cells -> chylomicrons -> lymph Vitamins Fat soluble (ADEK) Water soluble Vitamin B12 + intrinsic factor with micelles active transport Short bowel syndrome After resection of small intestine Dependent on remaining length: if >1m of distal ileum resected = bile salt malabsorption Short bowel syndrome Clinical course Initial diarrhea 2L / day Intestinal adaptation (mucosal hyperplasia, villi lengthening, crypt deepening) months -> years Treatment Parenteral nutrition Progressive oral feeding Small bowel transplantation Blind loop syndrome After laterolateral (side-to-side) anastomosis Dilation of the blind loop with distention Clinical findings: steatorrhea => bacterial deconjugation and dihydroxylation of bile salts Diarrhea => fatty acids entering the colon Hypocalcemia => calcium bound on fatty acids megaloblastic anemia => binding of vitamin in anaerobic bacteria Malnutrition => malabsorption of carbohydrates and proteins Blind loop syndrome Treatment: Surgical treatment Redo the anastomosis Broad spectrum antibiotics Octreotide Acute mesenteric ischemia Life threatening emergency Poor prognosis (5y survival 18 – 50%) Causes Arterial embolism (50%) (AMI / AF) Acute arterial thrombosis 25% Non-occlusive mesenteric ischemia (20%) Venous thrombosis Sharma A, Khanna R, Meena R, et al. (November 20, 2023) A Case Series on Acute Mesenteric Ischemia (AMI) Leading to Intestinal Gangrene Following Blunt Trauma to the Abdomen. Cureus 15(11): e49092. doi:10.7759/cureus.49092 Acute mesenteric ischemia Clinical presentation Non-specific Sudden diffuse abdominal pain out of proportion to the clinical exam Imaging CT / MRI angiography Case courtesy of Reem Nazeer Ali AbdulJabbar, Radiopaedia.org, rID: 179914 Thrombosis of the distal SMA Acute mesenteric ischemia Treatment Initial Fluid resuscitation Antibiotics Anticoagulation / antiplatelet drugs Surgical Laparotomy & embolectomy Necrotic bowel resection Angioplasty (if not necrotic intestine) Sharma A, Khanna R, Meena R, et al. (November 20, 2023) A Case Series on Acute Mesenteric Ischemia (AMI) Leading to Intestinal Gangrene Following Blunt Trauma to the Abdomen. Cureus 15(11): e49092. doi:10.7759/cureus.49092 Small intestine obstruction Pathophysiology Distention by swallowed air Sequestration of fluid inside the intestine Intestinal wall edema Bacterial proliferation and translocation Disruption of venous drainage -> arterial inflow Small intestine obstruction Site of obstruction Pathology External Adhesions Hernia Volvulus Bowel wall Inflammatory bowel disease (Crohn’s dis) Stricture Hematoma Intussusception Neoplasms Internal Foreign bodies Gallstone ileus Small intestine obstruction Clinical findings Proximal (high) Frequent and early vomiting No distention Intermittent pain Distal (low) Late feculent vomiting Colicky pain Marked distention Clinical findings Investigations Blood tests: ↑ Hct (Hemoconcentration) ↑ Creatinine (fluid sequestration) Leukocytosis electrolyte abnormalities Strangulation Ischemia >> bowel obstruction Early shock Abdominal tenderness and rigidity Blood tests: marked leukocytosis lactic acidosis Imaging: free intraperitoneal fluid gas within bowel wall air in the portal vein Perforation (free air) Small intestine obstruction Investigations Imaging studies: Plain abdominal film -> multiple air-fluid levels CT with contrast Diagnosis Location of obstruction Cause of obstruction Identify bowel ischemia Treatment Partial small bowel obstruction Nasogastric suction Fluid and electrolyte rescusitation Gastrografin test Surgical indication Persistent simple obstruction Suspicion of strangulation Signs of peritonitis or sepsis Surgical treatment Adhesiolysis Hernia repair Resection of non viable intestine and anastomosis Small intestine obstruction Treatment Supportive care iv fluid resuscitation Electrolyte imbalance correction Nasogastric suction Gastrografin test 100ml p.o. and radiography after 4h If no contrast in rectum => 96% need for surgery Small intestine obstruction Surgical indication Persistent simple obstruction (48h) Suspicion of strangulation Signs of peritonitis or sepsis Surgical treatment Adhesiolysis Hernia repair Resection of nonviable intestine Meckel’s diverticulum From incomplete obliteration of the omphalomesenteric duct At 1m from ileocecal valve Incidence of 1-3% Usually asymptomatic May have heterotopic colonic or pancreatic tissue Surgical treatment for symptomatic pediatric and asymptomatic adult patients Small intestine tumors Rare (