Free Surgical Foundation Question and Answers — Questions and Answers
Question 1: An open aorto-femoral bypass graft is performed on a 67-year-old man who has bilateral iliac occlusive disease and a 7 cm abdominal aortic aneurysm. The nurse observes that the left foot is cold and that there is no left femoral pulse four hours after surgery. The best course of action would be?
- immediate exploration of the left femoral anastomosis (Correct answer)
- four compartment left leg fasciotomy
- arteriography
- Heparin 10,000 units IV
Correct answer: immediate exploration of the left femoral anastomosis
The symptoms of a cold left foot and absent left femoral pulse four hours after an aorto-femoral bypass graft strongly suggest acute limb ischemia due to graft thrombosis or occlusion. This is a surgical emergency requiring immediate intervention to restore blood flow and prevent irreversible tissue damage. Delaying exploration for arteriography or attempting medical management with heparin would risk limb loss.
Question 2: Which of the following antibiotics is linked to red man syndrome?
- Levofloxacin
- Ciprofloxacin (Correct answer)
- Clindamycin
- Vancomycin
Correct answer: Ciprofloxacin
Red man syndrome is a well-known adverse reaction specifically associated with the rapid intravenous infusion of vancomycin. It is characterized by flushing, erythema, and pruritus, typically on the face, neck, and upper torso, and can be accompanied by hypotension. This reaction is due to histamine release, not an allergic reaction, and can be mitigated by slowing the infusion rate.
Question 3: Which of the following is the best sign that an IVC filter has to be placed?
- in a patient with a known distal vena caval thrombosis
- in a patient with recent pulmonary emboli despite anticoagulation with Coumadin (Correct answer)
- in a trauma patient with severe pelvic fractures and concomitant closed head injury
- prior to elective gastrectomy for cancer in a patient with an episode of DVT one month ago
Correct answer: in a patient with recent pulmonary emboli despite anticoagulation with Coumadin
The primary indication for an IVC filter is to prevent recurrent pulmonary embolism (PE) in patients who have a contraindication to anticoagulation or who experience recurrent PE despite adequate anticoagulation. A patient with recent pulmonary emboli despite being on Coumadin falls into the latter category, indicating a failure of medical management and a need for mechanical prevention of further emboli. This makes it the best indication among the choices.
Question 4: In a CT scan, the brightness of each pixel is proportional to the tissue's relative attenuation coefficient for x-rays, represented in Hounsfield units (HU). What tissue has the HIGHEST HU value out of the following?
- cortical bone (Correct answer)
- air
- muscle
- water
Correct answer: cortical bone
Hounsfield Units (HU) quantify the relative attenuation of X-rays by different tissues in a CT scan. Denser tissues absorb more X-rays and thus have higher HU values. Cortical bone is the densest tissue among the options, appearing brightest on a CT scan with HU values typically ranging from +1000 to +3000, significantly higher than water (0 HU), air (-1000 HU), or muscle (+40 to +100 HU).
Question 5: Tissue sensitivity to hypoxia is the primary cause of the initial symptoms of extremities compartment syndrome. The most susceptible structures to hypoxia are which of the following?
- skeletal muscle
- myelinated nerve
- Nonmyelinated nerve (Correct answer)
- skin
Correct answer: Nonmyelinated nerve
In compartment syndrome, increased pressure compromises blood flow, leading to tissue hypoxia. Nonmyelinated nerve fibers are the most susceptible structures to hypoxia and ischemia among the options provided. They are metabolically active and rely heavily on a continuous oxygen supply, making them quickly impaired by reduced blood flow, leading to the early neurological symptoms (paresthesias, pain) seen in compartment syndrome.
Question 6: Which of the following observations in a patient with abnormal bleeding would indicate primary fibrinolysis more likely than disseminated intravascular coagulation (DIC) as the source of the bleeding?
- increase in fibrin degradation product
- low fibrinogen levels
- prolonged aPTT
- normal platelet count (Correct answer)
Correct answer: normal platelet count
Disseminated Intravascular Coagulation (DIC) is characterized by widespread activation of the coagulation cascade, leading to the consumption of clotting factors and platelets, resulting in a low platelet count. In contrast, primary fibrinolysis involves the excessive breakdown of fibrin clots without significant activation of the coagulation cascade, meaning platelet consumption is not a primary feature. Therefore, a normal platelet count would strongly suggest primary fibrinolysis over DIC as the source of abnormal bleeding.
Question 7: Which of the following statements about fibrinolysis is untrue?
- pathologic fibrinolysis occurs when plasminogen which is free in plasma is activated
- ischemia is a potent activator of the fibrinolytic system
- plasmin acts only on cross-linked fibrin polymers (Correct answer)
- plasmin is essential to fibrinolysis
Correct answer: plasmin acts only on cross-linked fibrin polymers
The statement that plasmin acts *only* on cross-linked fibrin polymers is untrue. While plasmin is crucial for breaking down fibrin clots, it is a broad-spectrum protease that also degrades other coagulation factors, such as fibrinogen, factor V, and factor VIII. Therefore, its activity extends beyond just cross-linked fibrin, playing a wider role in regulating hemostasis.
