Chapter 33 – Inferior Vena Cava




Abstract






  • The inferior vena cava (IVC) is formed by the confluence of the common iliac veins, just anterior to the L5 vertebral body, and posterior to the right common iliac artery. As it courses superiorly towards the diaphragm, it lies to the right of the lumbar and thoracic vertebral bodies. It enters the thorax at T8, where the right crus of the diaphragm separates the IVC and aorta. In most individuals, there is a small segment of suprahepatic IVC, about 1 cm in length, between the liver and diaphragm, which is amenable to cross clamping.
  • The IVC receives four or five pairs of lumbar veins, the right gonadal vein, the renal veins, the right adrenal vein, the hepatic veins, and the phrenic veins. It is of practical importance to remember that all lumbar veins are below the renal veins and that between the renal veins and the hepatic veins, besides the right adrenal vein, there are no other venous branches. The left lumbar veins pass behind the abdominal aorta.
  • The confluence of the renal veins with the IVC lies posterior to the duodenum and the head of the pancreas.
  • The retrohepatic IVC is about 8–10 cm in length and is adhered to the posterior liver, helping to anchor the liver in place. In this liver “tunnel,” several accessory veins from the caudate lobe and right lobe drain directly into the IVC.
  • There are three major hepatic veins which drain the liver into the IVC. The extrahepatic portion of these veins is short, measuring about 0.5–1.5 cm in length. The right hepatic vein is the largest. In about 70% of individuals, the middle vein drains into the left hepatic vein to enter the IVC as a single vein.
  • The thoracic IVC is almost entirely in the pericardium.





Chapter 33 Inferior Vena Cava


Lydia Lam , Matthew D. Tadlock , and Demetrios Demetriades



Surgical Anatomy




  • The inferior vena cava (IVC) is formed by the confluence of the common iliac veins, just anterior to the L5 vertebral body, and posterior to the right common iliac artery. As it courses superiorly towards the diaphragm, it lies to the right of the lumbar and thoracic vertebral bodies. It enters the thorax at T8, where the right crus of the diaphragm separates the IVC and aorta. In most individuals, there is a small segment of suprahepatic IVC, about 1 cm in length, between the liver and diaphragm, which is amenable to cross clamping.



  • The IVC receives four or five pairs of lumbar veins, the right gonadal vein, the renal veins, the right adrenal vein, the hepatic veins, and the phrenic veins. It is of practical importance to remember that all lumbar veins are below the renal veins and that between the renal veins and the hepatic veins, besides the right adrenal vein, there are no other venous branches. The left lumbar veins pass behind the abdominal aorta.





    Figure 33.1 Anatomy of the inferior vena cava (IVC). Note the right renal artery coursing behind the IVC.





    Figure 33.2 The suprarenal IVC has no lumbar veins and thus poor collaterals. Ligation of the IVC in this location leads to renal failure.




  • The confluence of the renal veins with the IVC lies posterior to the duodenum and the head of the pancreas.



  • The retrohepatic IVC is about 8–10 cm in length and is adhered to the posterior liver, helping to anchor the liver in place. In this liver “tunnel,” several accessory veins from the caudate lobe and right lobe drain directly into the IVC.



  • There are three major hepatic veins which drain the liver into the IVC. The extrahepatic portion of these veins is short, measuring about 0.5–1.5 cm in length. The right hepatic vein is the largest. In about 70% of individuals, the middle vein drains into the left hepatic vein to enter the IVC as a single vein.



  • The thoracic IVC is almost entirely in the pericardium.



General Principles




  • The IVC is the most frequently injured abdominal vessel, following penetrating trauma. Blunt trauma to the IVC usually involves the retrohepatic part of the vein.



  • Patients with intra-abdominal IVC injury, who present to the hospital alive, typically have a contained retroperitoneal hematoma and, therefore, may initially appear to be hemodynamically stable.



  • Avoid femoral vein catheters in patients with penetrating abdominal trauma because of the possiblity of proximal iliac or IVC injury.



  • In abdominal gunshot wounds, obtain a plain abdominal radiograph prior to going to the operating room if time permits, as it helps determine missile trajectory and other structures at risk.



  • During induction of anesthesia in patients with severe intra-abdominal bleeding, there is a high risk of rapid hemodynamic decompensation or even cardiac arrest. The surgical team should be ready and the skin preparation should be performed before induction of anesthesia.



  • During exploration of a caval injury, there is high risk for air embolism. Prevent this complication by early direct compression, followed by proximal and distal control.



  • Because of the extensive collateral circulation below the renal veins, the infrarenal cava can be safely ligated with acceptable morbidity of lower extremity swelling that is usually temporary.



  • Following IVC ligation, the lower extremities and feet should be wrapped with elastic bandages to reduce edema. Monitor closely for extremity compartment syndrome.



  • Following packing or repair of IVC injuries, the patient should not be over-resuscitated.



Special Surgical Instruments




  • In addition to a standard trauma laparotomy instrument tray, vascular clamps with multiple lengths and angulations must be available.



  • A self-retaining retractor, such as Omni-Tract or Bookwalter.



  • A sternotomy set should be available in case a median sternotomy is needed for improved exposure of the retrohepatic IVC.



  • Surgical headlamp is important.



Patient Positioning




  • Supine, with upper extremities abducted to 90°. Skin antiseptic preparation should include the chest, abdomen, and groins.



  • Use upper and lower body warming devices.



Incisions




  • Extended midline trauma laparotomy from xiphoid to pubic symphysis.



  • The laparotomy may be extended through a subcostal incision to provide exposure to the retrohepatic IVC (see Chapter 22 General Principles of Abdominal Operations for Trauma)


Figure 33.3



(a) Addition of a right subcostal incision to the standard midline laparotomy improves the exposure of the retrohepatic veins. The subcostal incision is made 1–2 fingerbreadths below the costal margin. Avoid an acute angle between the two incisions to prevent ischemic necrosis of the skin.





(b) A median sternotomy may be added to the midline laparotomy in cases requiring access to the intrapericardial segment of the inferior vena cava for vascular occlusion of the liver, or to the heart for placement of an atriocaval shunt.



Exposure




  • In penetrating trauma, upon entering the peritoneal cavity, the usual findings include a large retroperitoneal hematoma with or without free intraperitoneal bleeding. In blunt trauma, the most likely finding is a retroperitoneal hematoma, usually retrohepatic.



  • Almost all retroperitoneal hematomas due to penetrating trauma should be explored, irrespective of size, to rule out an underlying vascular or hollow viscus injury. The only exception is a stable and nonexpanding retrohepatic hematoma. Surgical exploration of the retrohepatic vena cava or the hepatic veins is difficult and potentially dangerous.



  • Retroperitoneal hematomas due to blunt trauma rarely require exploration. However, paraduodenal hematomas or any large, expanding or leaking hematomas should be explored.



  • The infrarenal and juxtarenal IVC is best exposed by mobilization and medial rotation of the right colon, the hepatic flexion of the colon, and the duodenum.



  • The small bowel is eviscerated to the left of the patient and kept in place with warm and moist towels. The avascular white line of Toldt, lateral to the colon, is divided, using sharp dissection or electrocautery. The cecum, right colon, and hepatic flexure are mobilized and retracted medially.





    Figure 33.4 Medial rotation of the right colon combined with Kocher mobilization of the duodenum provides good exposure of the inferior vena cava, the right renal vessels, and the right iliac vessels.




  • Following the medial visceral rotation, the second portion of the duodenum, the Gerota’s fascia of the right kidney, and the iliopsoas muscle are exposed.



  • The duodenum is then mobilized medially with the Kocher maneuver by incising the lateral peritoneal attachments of the first, second, and proximal third portions of the duodenum. The C-loop of the duodenum and the pancreatic head are retracted medially to expose the inferior vena cava posteriorly.



  • The IVC is then visualized with the aorta to the left of IVC. The paired renal veins and the right gonadal vein are visualized draining into the IVC.


Sep 4, 2020 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 33 – Inferior Vena Cava
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