Slides with topics that are covered and were tested in the recent Absite exams. Nir Hus MD., PhD. http://www.nirhus.com

1. Absite topics 7-12
Nir Hus
Nir Hus

2. Q7: Timing of the first prophylactic
antibiotic dose
 The first prophylactic antibiotic dose should
provide a sufficient antibiotic serum level
throughout the surgery to combat organisms
most likely to cause a site infection.
 The first dose be timed to occur within 60
minutes before the surgical incision is made.
 If a fluoroquinolone or vancomycin is chosen for
prophylaxis, the first dose should be
administered within 120 minutes of the start of
surgery.
Nir Hus

3. Timing of the first prophylactic
antibiotic dose
 For most surgeries, the use of prophylactic
antibiotics should end within 24 hours after
surgery.
 Cefazolin or cefuroxime are suggested for
cardiothoracic surgery, with the
recommendtion of extension of
prophylactic antibiotics up to 72 hours to
avoid deep sternal infections.
Nir Hus

4. Surgery Prophylaxis Comments
Cardiothoracic Cefazolin or cefuroxime; if beta 72-hour duration
lactam allergy, vancomycin or advocated by some, but
clindamycin 24 hours is likely to be
adequate
Vascular Cefazolin or cefuroxime; if beta
lactam allergy, vancomycin
with or without gentamicin, or
clindamycin
Colon Oral: neomycin, with Combination of oral and
erythromycin base or parenteral prophylaxis
metronidazole may decrease infection
rates
Adapted with permission from Bratzler DW, Houck PM. Antimicrobial prophylaxis for
surgery: an advisory statement from the National Surgical Infection Prevention Project.
Clin Infect Dis 2004,38:1707.
Nir Hus

5. Timing of the first prophylactic
antibiotic dose
 Adaptedwith permission from Bratzler
DW, Houck PM. Antimicrobial prophylaxis
for surgery: an advisory statement from
the National Surgical Infection Prevention
Project. Clin Infect Dis 2004,38:1707.
Nir Hus

6. Q8: Incarcerated Groin Hernia
 Incidence of incarceration ~10% among
inguinal hernias.
 Cannot be reduced into the abdominal
cavity.
 Strangulated hernias have incarcerated
contents with vascular compromise.
 Frequently, intense pain is caused by
ischemia of the incarcerated segment.
Nir Hus

7. Q8: Incarcerated Groin Hernia
 Incarcerated inguinal hernias present with
abdominal distention, pain, nausea, and
vomiting due to intestinal obstruction.
 Plain abdominal X-rays may verify
intestinal obstruction in cases of
incarceration.
Nir Hus

8. Q9: Short Bowel Syndrome
 Pathophysiology:
 Dehydration
 Electrolyte derangements
 Acidic diarrhea
 Steatorrhea
 Malnutririon
 Weight loss
Nir Hus

9. Q9: Short Bowel Syndrome
 Etiology for extensive resection:
 Congenital anomalies leading to short bowel syndrom include –
 Intestinal atresia
 Midgut volvulus w/ intestinal necrosis
 Necrotizing enterocolitis.
 In Middle-aged adults –
 IBS
 Trauma
 In the elderly-
 Mesenteric ischemia
 Strangulated hernia
 Extensive resection due to malignancy.
Nir Hus

10. Q9: Short Bowel Syndrome
 Resection resulting in less than 120cm of intact
bowel leads to SBS.
 Resection of up to 50% of small bowel is
tolerated.
 Resection of up to 70% is tolerated if terminal
ileum and cecum are preserved.
 Infants may tolerate upto 85% of small bowel
resection.
Nir Hus

11. Q9: Short Bowel Syndrome
 Loss of the ileocecal valve results in rapid
emptying of enteral contents into the colon
and reflux of colonic bacterial flora into
small bowel.
 The entire jejunum can be resected
without serious adverse nutritional
sequela.
Nir Hus

12. Q9: Short Bowel Syndrome
 Adaptation:
 Cellularhyperplasia and bowel hypertrophy
occur over a 2- to 3-year period, increasing
the absorptive surface area.
 Fat absorption is most likely permanently
impaired.
Nir Hus

13. Q10: Malabsorption & Malnutrition
 Gastric hypersecretion
 Cholelithiasis
 Hyperoxaluria & Nephrolithiasis
 Diarrhea & Steatorrhea
 Intestinal Microflora
Nir Hus

14. Q10: Malabsorption & Malnutrition
 Gastric hypersecretion – in early postop period.
Increased acid load may injure distal bowel
mucosa  hypermotility & impaired absorption.
 Cholelithiasis – altered bilirubin metabolism after
ileal resection  increased risk of pigmented
gallstones stones that is 2nd to a decreased bile
salt pool. TPN also may lead to increased risk of
cholelithiasis.
Nir Hus

15. Q10: Malabsorption & Malnutrition
 Hyperoxaluria & Nephrolithiasis –
 Excessive fatty acids within the colonic lumen
bind intraluminal calcium.
 Unbound oxalate that normally is made
insoluble by Ca-binding and is excreted in
feces is thus, readily absorbed.
 This results in hyperoxaluria and calcium
oxalate urinary stone formation.
Nir Hus

16. Q10: Malabsorption & Malnutrition
 Diarrhea & Steatorrhea –
 Caused by rapid intestinal transit.
 Presence of hyperosmolar enteric contents.
 Disruption of enterohepatic bile acid
circulation.
 Fat absorption is most severly impaired by
ileal resection.
Nir Hus

17. Q10: Malabsorption & Malnutrition
 Intestinal Microflora –
 Loss of ileocecal valve permits reflux of
colonic bacteria into small bowel.
 Intestinal dysmotility increases colonization.
 Bacterial overgrowth & change in flora results
in pH alteration & deconjugation of bile salts.
 This results malabsorption, fluid loss,
decreased vit B12 absorption.
Nir Hus

18. Q11: Effect of ASA on Plt.
 Irreversiblyacetylates cyclooxygenase
 Results in inhibiting plt synthesis of
Thromboxane A2.
 Decreases plt function.
 Higher doses than > 80 – 160mg PO / day
donot have a higher efficacy.
Nir Hus

19. Q12: Synergism Ampicillin /
Sulbactam (Unasyn)
 PCN:
 GPC – streptoccocci, syphilis,
 GPR - Neisseria m., C. perfringens,
 Beta-hemolytic strep, antrax
 Not effective for Staph or Enterococcus
 Ampicillin/amoxicillin: PCN + Enterococcus coverage
 Unasyn: PCN + GPC (staph & strep), GNR +/-
anaerobic coverage, enterococci.
 NOT FOR Pseudomonas, Acinetobacter, or Serratia.
 Sulbactam & Clavulanic acid – are beta-lactamase
inhibitors.
Nir Hus