A 36-year-old woman is brought to the emergency department 20 minutes after being involved in a high-speed motor vehicle collision. On arrival, she is unconscious. Her pulse is 140/min, respirations are 12/min and shallow, and blood pressure is 76/55 mm Hg. 0.9% saline infusion is begun. A focused assessment with sonography shows blood in the left upper quadrant of the abdomen. Her hemoglobin concentration is 7.6 g/dL and hematocrit is 22%. The surgeon decided to move the patient to the operating room for an emergent explorative laparotomy. Packed red blood cell transfusion is ordered prior to surgery. However, a friend of the patient asks for the transfusion to be held as the patient is a Jehovah's Witness. The patient has no advance directive and there is no documentation showing her refusal of blood transfusions. The patient's husband and children cannot be contacted. Which of the following is the most appropriate next best step in management?

Transfusion of packed red blood cells

Consult hospital ethics committee

Administer high-dose iron dextran

A 35-year-old patient is brought into the emergency department post motor vehicle crash. Stabilization of the patient in the trauma bay requires endotracheal intubation. The patient has a laceration on the femoral artery from shrapnel and seems to have lost large quantities of blood. The patient is transfused with 13 units of packed red blood cells. His vitals are T 96.5, HR 150, BP 90/40. Even with the direct pressure on the femoral artery, the patient continues to bleed. Results of labs drawn within the last hour are pending. Which of the following is most likely to stop the bleeding in this patient?

Fresh frozen plasma and platelets

A 33-year-old pilot is transported to the emergency department after she was involved in a cargo plane crash during a military training exercise in South Korea. She is conscious but confused. She has no history of serious illness and takes no medications. Physical examination shows numerous lacerations and ecchymoses over the face, trunk, and upper extremities. The lower extremities are cool to the touch. There is continued bleeding despite the application of firm pressure to the sites of injury. The first physiologic response to develop in this patient was most likely which of the following?

Increased capillary refill time

Decreased systolic blood pressure

A 69-year-old woman is brought to the emergency department because of fatigue and lethargy for 5 days. She has also had weakness and nausea for the last 3 days. She has sarcoidosis, major depressive disorder, and hypertension. She had a stroke 5 years ago. Current medications include aspirin, nifedipine, prednisolone, fluoxetine, and rosuvastatin, but she has not taken any of her medications for 7 days due to international travel. Her temperature is 36.1°C (96.9°F), pulse is 95/min, and blood pressure is 85/65 mm Hg. She is lethargic but oriented. Examination shows no other abnormalities. Her hemoglobin concentration is 13.4 g/dL and leukocyte count is 9,600/mm3. Both serum cortisol and ACTH levels are decreased. This patient is most likely to have which of the following additional laboratory abnormalities?

Normal anion gap metabolic acidosis

A 27-year-old man is brought to the emergency department by emergency medical services. The patient was an unrestrained passenger in a head-on collision that occurred 15 minutes ago and is currently unresponsive. His temperature is 99.5°F (37.5°C), blood pressure is 60/33 mmHg, pulse is 180/min, respirations are 17/min, and oxygen saturation is 95% on room air. A FAST exam demonstrates fluid in Morrison’s pouch. Laboratory values are drawn upon presentation to the ED and sent off. The patient is started on IV fluids and an initial trauma survey is started. Twenty minutes later, his blood pressure is 95/65 mmHg, and his pulse is 110/min. The patient is further stabilized and is scheduled for emergency surgery. Which of the following best represents this patient’s most likely initial laboratory values?

Hemoglobin: 11 g/dL, Hematocrit: 33%, MCV: 88 µm^3

Hemoglobin: 10 g/dL, Hematocrit: 30%, MCV: 110 µm^3

Hemoglobin: 19 g/dL, Hematocrit: 55%, MCV: 95 µm^3

Hemoglobin: 7 g/dL, Hematocrit: 21%, MCV: 75 µm^3

Hemoglobin: 15 g/dL, Hematocrit: 45%, MCV: 90 µm^3

A 58-year-old cirrhotic man with ascites undergoes large volume paracentesis (6 liters removed). Four hours later, he becomes hypotensive (BP 80/50 mmHg) and tachycardic (HR 115/min). Labs show: Cr 2.1 mg/dL (baseline 1.0), Na+ 128 mEq/L, Hct 38%. What is the most appropriate immediate management?

5% albumin 6-8 grams per liter of ascites removed

Octreotide and midodrine for hepatorenal syndrome

Vasopressors to maintain blood pressure

Re-infusion of filtered ascitic fluid

Massive transfusion protocols for USMLE Step 1: High-Yield Surgery Lessons

MTP Initiation - When the Floodgates Open

Clinical Triggers: Uncontrolled hemorrhage, hemodynamic instability despite initial fluid resuscitation, or anticipated need for massive transfusion.
Scoring Systems (Predictive):
- ABC Score ≥2 points suggests need for MTP:
  - Penetrating mechanism (1 pt)
  - Positive FAST exam (1 pt)
  - SBP ≤90 mmHg (1 pt)
  - HR ≥120 bpm (1 pt)

Ultrasound FAST scan: Free fluid in Morison's pouch

⭐ The Assessment of Blood Consumption (ABC) score is a simple, rapid tool used in the emergency department to predict the likelihood of requiring massive transfusion. A score of 2 or more has high specificity and positive predictive value.

The Lethal Triad - Vicious Cycle of Doom

A catastrophic cascade in massive hemorrhage where three conditions feed into each other, leading to irreversible shock. Breaking the cycle is a key goal of damage control resuscitation.

Hypothermia (<35°C / 95°F)
- Causes: Environmental exposure, infusion of cold fluids, decreased heat production.
- Effect: Impairs platelet function and enzymatic activity of coagulation factors.
Acidosis (pH <7.2)
- Causes: Anaerobic metabolism from hypoperfusion (lactic acidosis).
- Effect: Impairs the function of coagulation enzymes.
Coagulopathy
- Causes: Dilution, consumption, and dysfunction (from acidosis/hypothermia).
- Effect: Worsens hemorrhage, deepening shock.

⭐ Clotting factor activity decreases by 10% for every 1°C drop in body temperature.

Lethal Triad of Trauma and Massive Transfusion Cycle

The Protocol - Balanced Blood Buffet

Activation: Triggered by rapid, significant blood loss (e.g., >4 units PRBCs in 1 hr) or specific trauma scores (e.g., ABC score ≥2).
Goal: Prevent or reverse the lethal triad of trauma (acidosis, hypothermia, coagulopathy) by replacing whole blood components.
Balanced Ratio (1:1:1):
- 1 unit PRBCs: For oxygen delivery.
- 1 unit FFP: Replaces clotting factors.
- 1 unit Platelets: For primary hemostasis.
Critical Additions:
- Tranexamic Acid (TXA): Antifibrinolytic given within 3 hours of injury.
- Calcium: Replete aggressively; citrate in blood products binds Ca²⁺, causing hypocalcemia.

⭐ The 1:1:1 ratio of PRBCs:FFP:Platelets is associated with improved survival in massive hemorrhage, primarily by preventing dilutional coagulopathy early on.

MTP Complications - The Aftermath Audit

Lethal Triad of Trauma: Acidosis, Hypothermia, Coagulopathy

Metabolic Derangements:
- Hypocalcemia: Most common. Citrate in pRBCs chelates calcium, causing myocardial depression.
- Hyperkalemia: From lysis of stored RBCs. Risk of arrhythmias.
- Acid-Base: Initial metabolic acidosis (lactate) followed by metabolic alkalosis as the liver metabolizes citrate.
Coagulopathy & Hematologic:
- Dilutional coagulopathy and thrombocytopenia.
- Depletion of labile Factors V and VIII.
Hypothermia:
- Infusion of cold blood products exacerbates acidosis and coagulopathy. Target >35°C.
Impaired Oxygen Delivery:
- Stored RBCs have ↓ 2,3-DPG, causing a left-shift in the oxyhemoglobin curve (↑ O₂ affinity).

⭐ High-Yield: The most frequent metabolic complication is hypocalcemia. Citrate preservative chelates ionized calcium, leading to paresthesias, prolonged QT, and myocardial depression. Monitor ionized calcium levels closely.

Massive transfusion is >10 units of PRBCs in 24 hours or >4 units in 1 hour.

Use a balanced 1:1:1 ratio of PRBCs:FFP:platelets to reconstitute whole blood and prevent dilutional coagulopathy.

The lethal triad of trauma consists of acidosis, hypothermia, and coagulopathy.

Monitor for hypocalcemia (citrate toxicity) and hyperkalemia (RBC lysis).

Goal-directed resuscitation aims to correct these abnormalities, guided by frequent lab monitoring.

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