Multivisceral Transplantation: Intraoperative Vascular Access Strategy




© Springer Science+Business Media New York 2017
Kathirvel Subramaniam and Tetsuro Sakai (eds.)Anesthesia and Perioperative Care for Organ Transplantation10.1007/978-1-4939-6377-5_42


42. Multivisceral Transplantation: Intraoperative Vascular Access Strategy



Charles D. Boucek 


(1)
Department of Anesthesiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA

 



 

Charles D. Boucek



Keywords
Multivisceral transplantationShort-gut syndromeTotal parenteral nutritionGraftImmunosuppressionInfection



Introduction


Patients who have short gut syndrome are unable to adequately absorb water and nutrients. Total parenteral nutrition (TPN) may maintain survival for a period of weeks to years, but the quality of life is often poor. Recurrent bloodstream infections [1], vascular thrombosis, and liver failure are life threatening complications. Multivisceral transplantation is a complex operation that has been used to replace nonfunctioning intestine and liver with graft organs [2]. Indications include: short gut syndrome due to infarction, multiple bowel resections or trauma; pseudo-obstruction; familial polyposis; and vascular failure of the portal or hepatic veins that prevent successful isolated liver transplantation. The graft may include liver along with intestine, stomach, and other organs. Substantial institutional commitment is needed for this to be successful; careful management is required well into the postoperative period. Immunosuppression to avoid organ rejection must be balanced against the need to prevent infection while the graft is continuously exposed to gastrointestinal contents.

Vascular access is needed for administration of medications, monitoring of hemodynamic parameters, sampling of venous and arterial blood, and replacement of fluids and blood. Third space fluid loss may be extensive and blood loss can be massive. Vascular clamping to permit native organ removal and graft placement may sequester intravascular volume; maintaining adequate preload under these circumstances may require rapid addition of volume to the nonsequestered vascular beds. Establishing adequate and perhaps redundant vascular access needs to be accomplished with deliberate speed; transplant operations are always emergencies when graft organs become available. Preoperative planning including a strategy for vascular access will improve the likelihood of a successful outcome [3].


Stages of the Operation


The stages of multivisceral transplantation are: preoperative evaluation, induction of anesthesia, establishment of vascular access and other monitors, laparotomy with removal of nonfunctioning native organs, placement of the graft, reperfusion, reestablishment of bowel continuity, and abdominal closure. Recovery is often prolonged and may include return to the operating room for additional surgery. Because the native small bowel is missing or removed during surgery, portal venous flow does not require veno-venous bypass as used in isolated liver transplants [4].


Preoperative Assessment


Candidates are often cachectic and have multiple comorbidities. They are frequently colonized with antibiotic resistant organisms that are therapeutic challenges if they gain entry to the systemic circulation through vascular access devices. While many patients undergoing isolated liver transplantation are hypo-coagulable, patients undergoing multivisceral transplantation are often hyper-coagulable [5]. TPN is usually administered through central venous lines. The administered fluids are excellent growth media; line infection and thrombosis is common [6]. Progressive loss of veins that can be accessed conveniently increases the urgency for transplantation and also makes it more difficult.

Meticulous sterile technique during placement and dressing of vascular lines cannot be overemphasized. Lines should be secured to prevent both inadvertent line removal and the advancement of exposed (and potentially contaminated) sections of long catheters into the circulation. All but small bore catheters intended for early removal should be sutured. Multivisceral transplant patients have fragile skin due to malnutrition and the use of steroids and other drugs. If skin adhesives are used skin tears may result.

A venogram of the major veins including jugular, subclavian, femoral, and iliac veins can identify which vessels are open [7]. Sonograms, computed tomography (CT), or magnetic resonance (MRI) studies may be alternatives [8]. Due to the underlying medical problems and the many phlebotomies, peripheral veins are usually exhausted by the time that transplantation is a consideration.

When central veins are blocked, blood return occurs through collateral channels. A system of well-developed collaterals may accommodate moderate additional flow but may not support massive transfusion. Bilateral occlusion of the jugular and subclavian veins can result in a superior vena cava syndrome equivalent with swelling of the face and upper extremities. Dilated veins on the chest wall may be noted; these superficial veins form anastomoses with abdominal veins permitting blood to return to the heart via the inferior vena cava or azygous system. This is referred to as a reverse caput medusa. Cannulation of these superficial veins is possible but they are usually distended, tortuous, and accommodate additional flow poorly; venipuncture sites may bleed profusely. Infused fluids may result in localized vascular congestion without restoring cardiac preload.


Anesthetic Induction and Monitoring


Anesthetic challenges include induction of anesthesia, adequate monitoring, and the ongoing delivery of appropriate fluids and medications to maintain hemodynamic stability both during surgery and into the recovery period.

Most patients should be considered to have “full stomachs” even if most of the small bowel has already been removed. Retained gastric and oral secretions, poor motility, and the emergent timing are all factors to consider; usually a rapid sequence induction of anesthesia is utilized if any reliable IV can be established. Other alternatives for anesthesia induction include intramuscular ketamine and succinylcholine for rapid sequence induction or alternatively, awake intubation under local anesthesia with inhalation induction after intubation. Intra-nasal administration of midazolam may help and if the risk of aspiration is felt to be low, inhalation induction by mask can be considered.

Following induction, monitors and definitive vascular access should be established. EKG, temperature, pulse oximetry, neuromuscular blockade monitors, and measurements of exhaled gases can follow standard anesthetic practice recognizing that adhesive electrodes are subject to dislodgement if they are near the surgical field. Blood pressure can be measured by cuff during induction, but direct measurement by percutaneous arterial line(s) permits continuous measurement. Arterial lines can be placed in the radial, ulnar, brachial, axillary, femoral, and dorsalis pedis arteries. As in liver transplantation, femoral arterial lines [9] usually give more reliable pressures than do radial lines after reperfusion. Femoral arterial lines may become temporarily unusable when the aorta is clamped to create an arterial anastomosis with the graft. A second arterial line in the upper extremities provides pressure monitoring during this period and permits pressure monitoring to be uninterrupted during sampling of arterial blood.

Continuous attention to the volume status is needed. Recurrent episodes of hypovolemia need to be minimized. A patient may recover from a single episode of hypovolemic or anemic stress [10], however, transplant operations are lengthy and each subsequent episode results in progressively poorer recovery. Volume overload results in tissue and pulmonary congestion. Edematous organs function poorly, are more difficult to implant, and in extreme cases may prevent abdominal closure. To maintain optimal preload, it is important to have a way to measure volume status [11, 12] and adequate means to replace fluid losses as they are occurring. Based on the venogram, patients can be categorized into three groups: patients who have patent veins both above and below the diaphragm; patients with blockages of veins equivalent to superior vena cava syndrome; patients with blockages equivalent to superior vena cava syndrome and also occlusions of the iliac system.


Vascular Access Strategies



Group One: Routine Vascular Access


Patients in the first group can undergo monitoring of preload with CVP and PA catheters inserted in the routine fashion. Skin preparation with antiseptics reduces the risk contamination. Likelihood of contamination is affected by site of insertion, how long the catheter remains in place, and any break in sterile technique in inserting or maintaining the catheter. During multivisceral transplantation, jugular veins are usually preferred over using the subclavian due to the risk of pneumothorax or arterial puncture. While pneumothorax can be treated with a chest tube, inadvertent puncture of the subclavian artery is more difficult to apply hemostasis.

If superficial veins are available conventional placement of IV catheters can be used. Catheter-over-needle devices are inserted through the skin into veins distended by use of a tourniquet, or alternatively into named veins using anatomic landmarks or ultrasound guidance [13]. The flow through a catheter is related to the viscosity of the fluid administered, the diameter of the catheter and the pressure gradient between the infusion device [14] and the intravascular space but may be difficult to predict [15]. Flow rate is inversely related to the length of the narrowest part of the catheter. Increasing the pressure of the infusion system can increase flow rate but carries risk of inadvertently infusing air and of injuring the vein. Instilling fluid under high pressure into a venous system that has outflow obstruction can lead to venous distension and regional edema formation. When high intravenous flow rates are needed a larger bore IV placed in a nonobstructed vein is usually preferred. Intravenous catheters come in a variety of lengths and diameters based on wire gauge. Catheter size is limited by the size of the vein. A large catheter can be challenging to place; it is often better to place a smaller catheter and then, using a guide wire and dilator, exchange it for one of a larger size. Care must be taken to avoid losing the guide wire into the circulation [16]. If this should happen, the lost wire can often be removed by interventional radiology using a snare. Lost wires must be removed. Lost wires can become infected and can migrate within the vascular space. If ignored, they can become locked into position by fibrous tissue; then surgical removal is required.

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Jul 9, 2017 | Posted by in Uncategorized | Comments Off on Multivisceral Transplantation: Intraoperative Vascular Access Strategy
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