Fluid Management & Blood Transfusion Flashcards

Which coagulation test specifically reflects the function of the extrinsic pathway and is used to monitor warfarin therapy?

Answer: Prothrombin Time (PT/INR)

The PT/INR measures the extrinsic pathway (tissue factor + factor VII) and the common pathway (factors X, V, II, fibrinogen); it is prolonged by warfarin because warfarin inhibits vitamin K-dependent factors including factor VII, which has the shortest half-life.

What is the primary clinical advantage of viscoelastic hemostatic assays (TEG/ROTEM) over conventional coagulation tests (PT/aPTT) in the perioperative setting?

Answer: Real-time point-of-care assessment of the entire clot formation, strength, and fibrinolysis process using whole blood

TEG/ROTEM provides dynamic assessment of the entire coagulation process from initial clot formation through clot strength and lysis using whole blood at the bedside within 30-60 minutes, enabling targeted hemostatic therapy compared to plasma-based conventional tests.

During massive hemorrhage with dilutional coagulopathy, which coagulation factor reaches critically low levels first and is the most sensitive indicator of hemostatic impairment?

Answer: Fibrinogen

Fibrinogen (factor I) reaches critically low levels first during massive hemorrhage because it is consumed in clot formation and is present in lower plasma concentrations (~2-4 g/L) compared to other factors; a fibrinogen level < 1.5-2 g/L is associated with increased bleeding.

What is the primary physiologic rationale for using albumin over crystalloids for volume resuscitation in patients with hypoalbuminemia?

Answer: Albumin restores oncotic pressure and expands intravascular volume with approximately 4-5 times less total infusion volume

Albumin, as an oncotic agent, expands plasma volume approximately 4-5 times more efficiently per mL administered than crystalloids by retaining fluid intravascularly through colloid osmotic pressure, reducing tissue edema from large-volume crystalloid resuscitation.

Large-volume infusion of which intravenous fluid is most likely to cause hyperchloremic non-anion gap metabolic acidosis?

Answer: 0.9% Normal Saline

0.9% Normal Saline contains 154 mEq/L of chloride (supraphysiologic compared to plasma's 103 mEq/L); large volumes cause hyperchloremia that competitively inhibits bicarbonate reabsorption in the renal tubules, resulting in hyperchloremic metabolic acidosis.

Intraoperative cell salvage (autotransfusion) is absolutely contraindicated in which clinical situation?

Answer: Surgery involving gross bacterial contamination of the operative field or resection of malignancy

Cell salvage is contraindicated when the surgical field is grossly contaminated with bacteria (risk of bacteremia/sepsis) or involves malignancy (risk of reinfusing tumor cells and hematogenous spread), as washing cannot reliably remove all contaminants or malignant cells.

What is the recommended hemoglobin transfusion threshold for patients with stable ischemic heart disease or known cardiovascular disease undergoing surgery?

Answer: Hemoglobin > 8 g/dL

Current ACC/AHA and ASA guidelines recommend a slightly more liberal transfusion threshold of Hgb > 8 g/dL for patients with cardiovascular disease, as the myocardium has limited ability to compensate for anemia through increased oxygen extraction due to its already high baseline oxygen extraction ratio.