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AMC CAT MCQ Examination (AMC Part 1)

Bleeding shock, wound care and tetanus

Q: A 29-year-old male driver arrives at the resuscitation unit in severe haemorrhagic shock following a high-speed collision. He has multiple open pelvic and femoral fractures. Vital signs are: heart rate 142 beats per minute, blood pressure 72/40 mmHg, and Glasgow Coma Scale score 14. He has received two litres of crystalloid fluid pre-hospital. Arterial blood gas shows a pH of 7.18, base excess of -11 mmol/L, and lactate of 6.8 mmol/L. The trauma team activates the Massive Transfusion Protocol. Which of the following resuscitation strategies is most consistent with current damage control resuscitation principles?

Activate the major haemorrhage protocol and give its balanced component packs with laboratory reassessment. Ongoing critical haemorrhage requires source control and a major haemorrhage protocol. Australian guidance supports at least one FFP unit per two RBC units and one adult platelet dose per eight RBC units. Common ratio notation uses platelet donor-unit equivalents; it must not be read as one adult platelet dose per RBC. Monitor temperature, calcium, fibrinogen and clotting and adjust treatment.

Q: A 46-year-old landscape gardener presents with a deep, dirty puncture wound to his left plantar foot after stepping on a rusted nail embedded in garden soil six hours ago. On examination, the wound is contaminated with foreign debris. The patient is uncertain of his childhood immunization history and knows he has not received any tetanus vaccine doses in at least twenty years. According to the Australian Immunisation Handbook, which of the following is the most appropriate tetanus prophylaxis regimen for this patient?

Administer one dose of tetanus toxoid vaccine and tetanus immunoglobulin at separate sites. Under the Australian Immunisation Handbook guidelines, this patient has sustained a tetanus-prone wound: a deep puncture wound heavily contaminated with soil and manure. For individuals presenting with a tetanus-prone wound who have an uncertain vaccination history or fewer than three documented prior doses of tetanus toxoid, the mandatory management is the concurrent administration of: (1) a dose of tetanus toxoid-containing vaccine (e.g., dTpa or ADT booster) to initiate active immunity (followed by completing the full three-dose primary vaccination course), AND (2) tetanus immunoglobulin (TIG, 250 units intramuscularly, or 500 units if greater than 24 hours old or heavily contaminated) to provide immediate passive immunity. The vaccine and the immunoglobulin must be administered using separate syringes at distinct anatomical sites (e.g., opposing deltoids) to prevent antibody-antigen neutralization. Administering vaccine alone leaves the non-immune patient unprotected during the critical incubation period, whereas withholding vaccine forfeits the opportunity to establish durable active immunity.

Key Takeaways

One adult platelet dose is not equivalent to one red-cell unit.
Reassess blood-component treatment with clinical findings and laboratory or viscoelastic results.
Tetanus prophylaxis depends on wound type and vaccination history.

Last updated: October 2026

Haemorrhagic Shock & The Australian Massive Transfusion Protocol

American College of Surgeons (ACS) Haemorrhagic Shock Classification

Blood Loss (mL): Class I: $< 750\text{ mL}$ ; Class II: $750\text{ to }1500\text{ mL}$ ; Class III: $1500\text{ to }2000\text{ mL}$ ; Class IV: $> 2000\text{ mL}$
Blood Loss (% Volume): Class I: $< 15\%$ ; Class II: $15\%\text{ to }30\%$ ; Class III: $30\%\text{ to }40\%$ ; Class IV: $> 40\%$
Heart Rate (bpm): Class I: Normal ( $< 100$ ); Class II: Tachycardia ( $> 100$ ); Class III: Marked ( $> 120$ ); Class IV: Extreme ( $> 140$ )
Blood Pressure: Class I: Normal; Class II: Normal (narrow pulse pressure); Class III: Hypotension; Class IV: Severe hypotension
Respiratory Rate: Class I: $14\text{ to }20$ ; Class II: $20\text{ to }30$ ; Class III: $30\text{ to }40$ ; Class IV: $> 35$ (tachypnoea)
Urine Output (mL/h): Class I: $> 30$ ; Class II: $20\text{ to }30$ ; Class III: $5\text{ to }15$ ; Class IV: Negligible / anuria
Mental Status: Class I: Slightly anxious; Class II: Mildly anxious; Class III: Confused, agitated; Class IV: Lethargic, comatose
Fluid Replacement: Class I: Crystalloid; Class II: Crystalloid; Class III: Blood products + crystalloid; Class IV: Massive Transfusion Protocol

Modern Damage Control Resuscitation (DCR)

Permissive Hypotension: Target a systolic blood pressure of $80\text{ to }90\text{ mmHg}$ (mean arterial pressure $50\text{ to }65\text{ mmHg}$ $50 to 65 mmHg$ ) until surgical or radiological haemostasis is achieved. Overzealous fluid resuscitation increases hydrostatic pressure, dislodges immature clots ("popping the clot"), and worsens bleeding.
- Critical Exception: In patients with concurrent severe traumatic brain injury (TBI), maintain systolic blood pressure $\ge 100\text{ to }110\text{ mmHg}$ ( $MAP \ge 80\text{ mmHg}$ ) to ensure cerebral perfusion.

Critical bleeding protocol: In haemorrhagic shock, initiate the local major-haemorrhage packs while obtaining bleeding control. The Australian guideline specifies minimum ratios of one FFP unit for two RBC units and one adult platelet dose for eight RBC units. Platelet donor-unit ratios cannot be interpreted as adult-dose ratios: an adult pool contains multiple donor units. Use clinical response, clotting studies or viscoelastic testing to adjust subsequent components, and correct low ionised calcium and fibrinogen while preventing hypothermia.

Early Tranexamic Acid (TXA): Administer a $1\text{ g}$ IV bolus over 10 minutes within 3 hours of injury, followed by an IV infusion of $1\text{ g}$ over 8 hours (CRASH-2 trial). Mortality benefit is lost, and harm occurs, if administered after 3 hours.
Combating the Lethal Triad:
- Hypothermia: Actively warm patients (target core temperature $> 36.0^\circ\text{C}$ ).
- Acidosis: Maintain perfusion, avoid unbuffered crystalloids (target pH $> 7.2$ ).
- Coagulopathy: Maintain ionized calcium $> 1.1\text{ mmol/L}$ (hypocalcaemia from citrate toxicity causes refractory hypotension), administer cryoprecipitate if fibrinogen $< 2.0\text{ g/L}$ , and maintain platelet count $> 50 \times 10^9\text{/L}$ ( $> 100 \times 10^9\text{/L}$ in TBI).

Surgical Wound Care & Australian Tetanus Prophylaxis

Surgical Wound Classification

Clean: Uninfected operative wound where no inflammation is encountered and the respiratory, alimentary, genital, or urinary tract is not entered (e.g., elective hernia repair, thyroidectomy). Infection rate $< 2\%$ .
Clean-Contaminated: Operative wound in which the respiratory, alimentary, genital, or urinary tract is entered under controlled conditions without unusual contamination (e.g., elective cholecystectomy, elective appendicectomy). Infection rate $< 10\%$ .
Contaminated: Open, fresh accidental traumatic wounds, or operations with gross spillage from the gastrointestinal tract or acute non-purulent inflammation (e.g., gross bile spillage, open fracture within 4 hours). Infection rate $15\%\text{ to }20\%$ .
Dirty / Infected: Traumatic wounds with retained devitalized tissue, foreign bodies, or existing clinical infection (e.g., perforated diverticulitis with faecal peritonitis, drained intra-abdominal abscess). Infection rate $> 30\%$ .

Wound Closure Techniques

Primary Closure (First Intention): Direct approximation of wound edges with sutures, staples, or adhesive strips immediately after creation. Indicated for clean and clean-contaminated wounds with minimal tissue loss and viable margins.
Secondary Closure (Second Intention): The wound is intentionally left open to heal by formation of granulation tissue, wound contracture, and re-epithelialization. Indicated for dirty/infected wounds, abscess cavities, animal bites, and heavily contaminated wounds.
Delayed Primary Closure (Tertiary Intention): The contaminated wound is debrided and left open with dressings or negative-pressure wound therapy for 3 to 5 days. Once bacterial counts decline and healthy granulation tissue appears, the wound is closed primarily.

Australian Tetanus Immunization Guidelines

Under the Australian Immunisation Handbook, management depends on wound characteristics and documented vaccination history.

Tetanus-Prone Wounds: Compound fractures, bite wounds, deep puncture wounds, wounds contaminated with soil, manure, or saliva, burns, tissue avulsions, and wounds older than 6 hours with devitalized tissue.
$\ge 3$ prior doses, last dose $< 5$ years ago: Clean Minor Wound: No vaccine, No TIG; Tetanus-Prone Wound: No vaccine, No TIG
$\ge 3$ prior doses, last dose $5\text{ to }10$ years ago: Clean Minor Wound: No vaccine, No TIG; Tetanus-Prone Wound: Give 1 dose tetanus toxoid (ADT booster); No TIG
$\ge 3$ prior doses, last dose $> 10$ years ago: Clean Minor Wound: Give 1 dose tetanus toxoid; No TIG; Tetanus-Prone Wound: Give 1 dose tetanus toxoid; No TIG
Uncertain or $< 3$ prior doses: Clean Minor Wound: Give 1 dose tetanus toxoid (and complete 3-dose course); No TIG; Tetanus-Prone Wound: Give 1 dose tetanus toxoid AND give Tetanus Immunoglobulin (TIG 250 units) at separate anatomical sites

Primary references (checked 7 October 2026): NSW 2026 burn fluids; Australian critical bleeding guideline.

Test Your Knowledge

A 29-year-old male driver arrives at the resuscitation unit in severe haemorrhagic shock following a high-speed collision. He has multiple open pelvic and femoral fractures. Vital signs are: heart rate 142 beats per minute, blood pressure 72/40 mmHg, and Glasgow Coma Scale score 14. He has received two litres of crystalloid fluid pre-hospital. Arterial blood gas shows a pH of 7.18, base excess of -11 mmol/L, and lactate of 6.8 mmol/L. The trauma team activates the Massive Transfusion Protocol. Which of the following resuscitation strategies is most consistent with current damage control resuscitation principles?

Infuse rapid warm crystalloids to achieve a normal systolic blood pressure above 120 mmHg

Administer intravenous tranexamic acid only after laboratory confirmation of fibrinolysis

Activate the major haemorrhage protocol and give its balanced component packs with laboratory reassessment

Withhold all plasma and platelet transfusions until formal laboratory coagulation returns

Test Your Knowledge

A 46-year-old landscape gardener presents with a deep, dirty puncture wound to his left plantar foot after stepping on a rusted nail embedded in garden soil six hours ago. On examination, the wound is contaminated with foreign debris. The patient is uncertain of his childhood immunization history and knows he has not received any tetanus vaccine doses in at least twenty years. According to the Australian Immunisation Handbook, which of the following is the most appropriate tetanus prophylaxis regimen for this patient?

No tetanus vaccination or immunoglobulin is required because the wound occurred six hours ago

Administer one dose of adult tetanus-diphtheria toxoid vaccine only, with no immunoglobulin

Administer tetanus immunoglobulin alone and schedule the first tetanus vaccine in four weeks

Administer one dose of tetanus toxoid vaccine and tetanus immunoglobulin at separate sites

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