splanchic Flashcards
What is Viscera
Def: pertaining to the internal organs located within the ventral body cavity
Thoracic Cavity- above diaphragm
a. left pleural cavity
b. right pleural cavity
c. mediastinal cavity (includes pericardial
Abdominopelvic Cavity
a. abdominal cavity- stomach, liver, spleen, GI, pancreas, kidneys…
b. pelvic cavity- last part of large int. and reproductive organs
Splanchnic circulation will refer to the
vasculature w/in the abdominopelvic cavity prior to the iliac bifurcation with the exception of renal vessels.
kidneys are not considered part of splanchnic system. because
Due to positioning, function, independent autoregulation, and direct aortic and IVC drainage,
CPB and Splanchnic Circulation
Limitations of research
- Small sample size
- Difficulty in monitoring abdominal viscera and correlating to outcomes
- Conflicting data
- Controlling for other variables
risk factors for splanchic circulation and bypass
age > 65, dialysis, IABP (2o), +valve procedure, urgency
Release into small intestine controlled by
pyloric sphincter
how long is small intestine and how much food is absorbed here
20 ft. 90%
Duodenum- first
10”, serves as “mixing bowl” for chyme and digestive enzymes from liver and pancreas
Jejunum-
approx 8’, primary site of chemical digestion and nutrient absorption
Ileum-
approx 12’, last section before large int. Large [ ] of lymphoid nodules to protect SI from bacteria in LI.
Large Intestine
(5ft)
•Small amount of nutrient absorption, primarily vitamins from bacterial byproducts, fluid, and bicarb resorption
•Compaction and storage of chyme into fecal matter
CPB results in an increase in intestinal blood flow due to
a decrease in resistance
increase BF is independent of
T, pH, or pCO2. (autoregulation?)
Intestinal BF during CPB seems to be independent of
MAP and dependent on Q
Extensive use of vasoconstrictors during CPB exacerbates the risk
inadequate mesenteric perfusion
Takeaway: Cardiac surgery is associated with a relatively low incidence of GI complications but those complications cause
a vastly disproportionate level of mortality
Risk = probability X severity
Pancreas
•Primary function is
production of digestive enzymes and buffers (NaHCO3) to neutralize acidic chyme.
Several arterial blood sources from pancreas
splenic, hepatic, and sup. Mesenteric
pancreas is 99%
exocrine
Alpha cells
produce glucagon
beta cells
produce insulin
delta cells
produce somatostatin/tropin to suppress insulin and glucagon release
F cells-
pancreatic polypeptide; inhibits gall bladder contraction and some regulation of enzyme production
Acinar Cells comprise
99% of pancreas
Amylase
break down starch and carbs
lipase
breaks down lipids
nuclease breaks down
nucleic acids
Proteolytic enzymes
Proteases attack large proteins
•Peptidases break small peptides into amino acids
Elevated [amylase], a common indicator
for pancreatic injury did not correlate to negative post-op symptoms Amylase more sensitive, Lipase more specific
Pancreatitis occurs infrequently
(0.1-0.8%), but carries ↑ mortality
risk factors for pancreatitis
CPB time and hypotension secondary to low cardiac output syndrome
Mild pancreatitis carries
50% mortality
Severe pancreatitis carries
67-100 %
Much higher incidence of pancreatic injury post-CPB in
peds (4-8%)
Lab tests for pancreatitis in peds are
trypsinogen-2 and trypsin-2-α 1-antitrypsin
Red pulp
big honking filter and storage
White pulp:
lymphoid tissues
Post-splenectomy patients have a substantially greater risk of
infection and a 33% greater risk of future MIs.
Blood flow supplied by hepatic artery at
400cc/min and portal vein at 1000cc/min
liver Drains to the
IVC just below the diaphragm
use caution in placing venous
cannula to avoid obstruction and portal HTN.
Liver
1.Metabolic Regulation
All blood leaving the absorptive sections of the GI tract flows into the liver via the hepatic portal vein.
•This allows nutrients and toxins to be removed, stored, or allowed into the systemic circulation
•Intrinsic regulation determines nutrient storage or release
Liver
2.Hematological Regulation
Removal of damaged formed elements or pathogens via Kupfer cells
•Plasma protein synthesis
•Antibody, toxin, and hormone removal occur by various mechanisms
•Carboxylation of vit K dependent coagulation factors
Liver
3.Bile production
•
Approx. 1L produced each day
•Necessary for lipid digestion
•Stored in gall bladder and released upon lipid detection in the duodenum (cholecystokinin stimulates bile production and gallbladder contraction)
•Over concentrated bile leads to “gall stones”
Hepatic blood flow increases
slightly during CPB. Perfusion is ↑ with ↑Q.
cpb and liver. Hypothermia is primary factor in decreased
clearance of drugs (Although not all drugs illustrate ↓C)
may show hepatic markers of injury
Valve procedures, transfusions, and prolonged CPB times
Hepatic tests:
–Albumin
a hepatic function lab
Serum glutamic and oxaloacetic transaminase (SGOT) / Aspartate aminotransferase (AST) and Serum Glutamic pyruvic transaminase (SGPT) / Alanine aminotransferase (ALT
are fairly specific hepatocellular leakage enzymes
Total Bilirubin:
•Unconjugated
water insoluble
conjugated or direct bilirubin
water soluble
Alkaline phosphatase (ALP) is specific
to the liver’s biliary tree and represents biliary damage or cholestasis
–Others (INR, PT, LDH, 5’ Nucleotidase (5’NTD)
Dopaminergic (Dopamine & Dobutamine) drugs help
dilate splanchnic vessels during massive pressor administration for sepsis (explain)
Fenoldopam mesylate (Corlopam)
is a selective D₁ agonist with no β effects, therefore best choice for splanchnic perfusion
Unlike the brain or kidneys during CPB
there appears to be a muted autoregulatory response to the splanchnic circulation
Higher pressures do not seem to aid in
splanchnic perfusion except to liver (overcome portal and IVC P).
Although there is a low incidence of splanchnic injury,
the consequences carry high mortality rates.
The one constant is that longer CPB times have
higher incidence of post-op complications.
Pulsatile perfusion may ameliorate some short term dysfunction but
has not been proven to reduce gross injury.
In theory, increasing CPB flow during longer pumps times may
reduce complications
OPCAB splanchic
No apparent benefit
Pre-existing conditions that predispose patients to splanchic injury
(ie ulcer), advanced age, atherosclerosis, redo procedures, and combined procedures
