Causes and Detection of Liver Ischemia

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Causes and Detection of Liver Ischemia

• Effect Of Intermittent Liver Ischemia On Outcome
  In Patients With Hepatocellular Carcinoma On
  Liver Cirrhosis
• J Med Invest. 1999 Aug46(3-4)205-12.
• Harada M, et. al.
• CT Of Focal Hepatic Injury Due To Surgical
  Retractor
• AJR Am J Roentgenol. 1996 Mar166(3)599-602.
• Yassa NA, Peters JH.

Presented by John Yu March 25, 2005
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Smart Organ Retractor ProjectMentors Greg
Fischer and Mark Talamini, MDPartners Sunipa
Saha and Jen Horwat

• Developing manual and laparoscopic retractors
  with both force and ischemia sensors on each
• Conducting experiments with both retractors to
  relate force and ischemia over time
• Improving current system with a pattern of
  sensors and a full calibration to standard
  pulse-oxidation values

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Background on Liver Ischemia

• Hepatic (liver) ischemia is a deficiency of blood
  or oxygen supply to the liver that causes injury
  to liver cells.
• Typically caused by Clamping liver during liver
  surgery or Liver retraction for long periods
  during gastric surgery
• 15 to 20 min normothermic ischemia tolerance

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Paper Selection

• Effect Of Intermittent Liver Ischemia On Outcome
  In Patients With Hepatocellular Carcinoma On
  Liver Cirrhosis
• CT Of Focal Hepatic Injury Due To Surgical
  Retractor

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Summary of Problem

• Normal human liver has prolonged normothermic
  ischemia of up to 1 hr without significant
  complications
• In cirrhotic human liver, maximum safe ischemia
  time undetermined
• Methods varied by hepatic occlusion amount

http//health.allrefer.com/health/hepatic-ischemia
-liver-blood-supply.html
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Key Results

• Major complications tended to occur in the
  patients with length of ischemia exceeding 90
  minutes.
• Ischemic time has a much more significant factor
  on amount and severity of complications than
  occlusion amount.
• Intermittent normothermic ischemia (15 min
  clamped, 5 min unclamped) may be tolerated for up
  to 180 minutes in cirrhotic patients

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Effect Of Intermittent Liver Ischemia

• Methods
• 3 groups (no, hemi, full hepatic occular)
• summary of groups
• Group A 56.0-6.9
• Group B 61.8-5.8
• Group C 62.5-8.5
• Group A did not need to immobilize the right
  lobe, while B, C did
• Similar Tumor locations, and methods and
  approaches for tumor removal

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Effect Of Intermittent Liver Ischemia

• Intraoperative characteristics

Harada M, et. al. 1999
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Effect Of Intermittent Liver Ischemia

• Complications

Harada M, et. al. 1999
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Effect Of Intermittent Liver Ischemia

• Discussion of Results
• Patients with cirrhotic liver have a greater
  chance of complications than patients with normal
  livers
• Time limit of safe ischemia not accurately
  determined
• Major complications tend to occur with extended
  ischemic time

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CT of Focal Hepatic Injury

• Problem Establish link between surgical
  retraction and CT detection of focal hepatic
  injury
• Method
• 250 consecutive abdominal CT scans
• 2-6 months after surgery for gastric cardia
• 10 injured livers were found

Yassa NA, et. al. 1996
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CT of Focal Hepatic Injury

• Results
• CT appearance most likely focal hepatic necrosis
  from retractor compression
• 6 of 10 patients had visible damage, and all had
  visible damage after image enhancement
• Most Hepatic injuries are minor and require no
  operative intervention
• Complete healing typically 3.5 months to 6 months

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CT of Focal Hepatic Injury
Yassa NA, et. al. 1996
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Relevance to Project

• Established Purpose of Smart Retractor Project
• 1. Prolonged Hepatic Ischemia
• Tends to lead to major complications
• Can result in long-term damage to the liver
• 2. One cause of Hepatic Ischemia is from
  Retractor compression

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Future Improvements

• Measure Force vs. Time vs. Ischemia
• Incorporate CT scans as analysis tool
• Develop new protocols for retraction, and new
  organ retractors that limit ischemia