Acute renal failure occurs following repair of a ruptured

Discussion in 'MRCS Forum' started by Lona., Dec 9, 2007.

  1. Lona.

    Lona. Guest

    Acute renal failure occurs following repair of a ruptured abdominal aortic aneurysm in a 72-yrs-old man with a straight tube graft. His weight has been rising, his lungs show rales at both bases, and he is dyspneic. Consultants have suggested continuous arteriovenous hemofiltration (CAVH). Characteristics of CAVH include -
    a- CAVH is useful only in hemodynamically stable patients
    b- CAVH requires placement of large-bore (8 French) arterial and venous catheters, usually in the femoral vassals
    c- CAVH is not effective in treating hypovolemia
    d- Continuous heparinization of the patient who undergoes CAVH unnecessary
    e- During CAVH, blood flow is maintained by a mechanical extracorporeal pump-oxygenator
  2. Lona.

    Lona. Guest

    Answer: b. (Greenfield, 2/e, pp 238-239) Continuous arteriovenous hemofiltration (CAVH) is a relatively new method of therapy for acute renal failure in the intensive care unit. Continuous blood flow is maintained by the hydrostatic pressure gradient between an inflowing arterial cannula and the venous cannula that returns blood to the patient. The blood passes through an extracorporeal membrane, which clears an ultra-filtrate up to 12 L/day. This volume is replaced with an intravenous solution at a rate that achieves the desired fluid balance. CAVH in the surgical patient with acute renal failure allows a slow and continuous removal of fluid and is particularly advantageous in the volume-overloaded patient. Unlike traditional hemodialysis, it can be used over a wide range of blood pressures in the unstable patient. Solutes (such as urea nitrogen and potassium) that are not in the replacement intravenous fluid are also cleared. The main complications associated with CAVH relate to vascular access problems: arterial thrombosis, aneurysm, fistula formation, and infection. Anticoagulantion, with its concomitant bleeding risks, must be maintained to prevent thrombosis of the filter and cannulas. The potential for electrolyte imbalance during long-term CAVH necessitates careful monitoring.

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