Chapter 93 Colon Flashcards
Blood supply to the cecum
ileocolic artery (from common colic from cranial mesenteric artery)
Blood supply to the ascending colon
Proximally - ileocolic artery
Distally - right colic artery
Blood supply to the transverse colon
Right colic and middle colic artery
Blood supply to the descending colon
Proximal half: Middle colic artery
Distal half: left colic branch of caudal mesenteric artery
Most distal portion: cranial rectal artery
What is the predominant cell type during the lag/inflammation phase in colonic healing
Neutrophils then after 2-3 days monocytes and macrophages
How does the inflammation/lag phase begin
Initiated by platelets as hemostasis occurs and a fibrin clot forms
Why is dehiscence most likely to occur during the first 72-96 hours post colonic closure
Inflammation activates bowel wall collagenase, which degrades collagen within the wound, eroding the foundation in which sutures are anchored
What do fibroblasts produce during the proliferative phase
immature collagen
Collagen make up during the proliferation phase
30-40% type III in developing granulation tissue
What important step occurs during proliferative phase in regards to collagen synthesis
Hydroxylation of lysine and proline which are amino acids needed for collagen synthesis
What is the key to colonic healing
collagen produced by submucosa and smooth muscle cells
Weakness in colon healing due to
Weakness results from collagen degradation by matrix metalloproteinases and collagenase
Matrix metalloproteinase activity decreases after day 3
Colonic wound strength after 48 hours then at 4 months
30% at 48 hours
75% at 4 months
List local detrimental factors in GI healing
Tissue hypoperfusion
Wound tension – if < 40mmHg PaO2 collagen formation will not occur
Poor apposition
Infection
Distal obstruction*
List systemic detrimental factors in GI healing
Hypovolemia
Zinc and iron deficiency
Blood transfusion
Medication (chemotherapy agents and chronic steroids)
Immunodeficient
Uncontrolled DM
Icterus
