Subinternship Surgery · Year 4 · from Subinternship Surgery
Case 2: Ruptured Abdominal Aortic Aneurysm
Patient Presentation
Demographics: 74-year-old male
Chief Complaint: Sudden onset severe back pain
History of Present Illness: Mr. Thompson is a 74-year-old male brought by EMS with sudden onset of severe back pain that began 45 minutes ago while he was gardening. He describes the pain as "tearing" in nature, radiating from his mid-back to his left flank. He felt lightheaded and nearly lost consciousness shortly after the pain began. EMS reports his blood pressure was 78/50 in the field but improved to 92/60 after 1 liter of normal saline.
Past Medical History:
- Known 5.8 cm infrarenal AAA (last surveillance 6 months ago)
- Hypertension (poorly controlled)
- 50 pack-year smoking history
- COPD
- Coronary artery disease (prior MI, 3 years ago)
Physical Examination:
- Vitals: T 36.2C, HR 124, BP 88/52, RR 28, SpO2 94% on 4L NC
- General: Pale, diaphoretic, appearing acutely ill
- Cardiovascular: Tachycardic, distant heart sounds
- Abdomen: Mildly distended, palpable pulsatile mass in epigastrium, diffuse tenderness
- Extremities: Mottled bilateral lower extremities, diminished femoral pulses
- Mental status: Confused, answering questions inappropriately
Clinical Questions
- What is your immediate differential diagnosis, and how do you prioritize evaluation?
Differential Diagnosis for Sudden Severe Back Pain + Hypotension: | Diagnosis | Key Features | Probability | |-----------|--------------|-------------| | Ruptured AAA | Known AAA, pulsatile mass, shock | HIGH | | Aortic dissection | Tearing pain, pulse deficit | Consider | | Acute MI | Prior CAD, but pain atypical | Less likely | | Acute pancreatitis | No risk factors provided | Less likely | | Perforated viscus | Usually peritoneal signs | Less likely |
Critical Point: In a hemodynamically UNSTABLE patient with known AAA presenting with this clinical picture, the diagnosis of ruptured AAA is presumed. Do NOT delay for CT scan - patient should go directly to OR.
- Describe the initial resuscitation strategy for ruptured AAA.
Damage Control Resuscitation Principles:
| Component | Target | Rationale | |-----------|--------|-----------| | Permissive hypotension | SBP 70-90 mmHg | Higher pressure increases ongoing hemorrhage | | Massive transfusion protocol | Activate immediately | 1:1:1 ratio pRBC:FFP:platelets | | Limit crystalloid | 1-2L maximum | Dilutional coagulopathy, hypothermia | | Maintain temperature | >35C | Prevent lethal triad | | Tranexamic acid | 1g IV | Consider if available |
Immediate Actions:
- Two large-bore IVs (14-16 gauge)
- Type and crossmatch 6 units pRBC STAT
- Activate massive transfusion protocol
- Call vascular surgery immediately
- Alert OR that patient is coming NOW
- Hold off on aggressive fluid resuscitation
- The vascular surgeon is 15 minutes away. What should you be doing during this time?
Sub-Intern Responsibilities While Awaiting Surgeon:
| Task | Action | |------|--------| | Airway | Maintain current status; prepare for RSI if mental status declines | | Access | Ensure 2 large-bore IVs, consider placing arterial line | | Blood | Confirm blood bank has MTP activated, O-negative blood available | | Consent | Obtain emergent consent from patient or family (telephone consent if needed) | | Documentation | Document timeline of events, vitals, interventions | | Communication | Keep family informed of critical nature | | OR preparation | Confirm OR is ready, equipment available (cell saver, warming devices) |
Do NOT:
- Leave patient unattended
- Delay for additional imaging if unstable
- Over-resuscitate with crystalloid
- What are the key prognostic factors for ruptured AAA?
Prognostic Factors Affecting Survival:
| Factor | Better Prognosis | Worse Prognosis | |--------|------------------|-----------------| | Hemodynamic status | Stable or responds to resuscitation | Refractory shock | | Mental status | Alert | Obtunded/unconscious | | Time to OR | <60 minutes from rupture | Prolonged delay | | Age | <70 years | >80 years | | Comorbidities | Minimal | Significant cardiac/renal disease | | Cardiac arrest | No | Pre-operative CPR |
Overall Statistics:
- Ruptured AAA mortality: ~50% (even with repair)
- Elective AAA repair mortality: 1-2%
- This contrast emphasizes the importance of surveillance and elective repair
Clinical Image
Image: CT angiography demonstrating a ruptured infrarenal abdominal aortic aneurysm with retroperitoneal hematoma. The contrast extravasation indicates active hemorrhage. In hemodynamically unstable patients, CT should not delay operative intervention. Source: Wikimedia Commons.
Image Attribution: Abdominal aortic aneurysm CT. Wikimedia Commons. CC BY-SA 3.0. URL: https://commons.wikimedia.org/wiki/File:Aortic_aneurysm_CT.jpg
Summary Points
- Small Bowel Obstruction Classification: Differentiate partial vs. complete, simple vs. strangulated, and closed-loop configurations - each determines management urgency
- Strangulation Signs: Constant pain, focal peritoneal signs, fever, tachycardia, elevated lactate, and leukocytosis indicate bowel compromise requiring emergent surgery
- SBO Management Decision: Non-operative trial (48-72 hours) is appropriate for partial obstruction without strangulation; complete obstruction with strangulation requires immediate surgery
- Ruptured AAA Recognition: Classic triad of hypotension, back/abdominal pain, and pulsatile mass - but all three present in minority of cases; maintain high suspicion
- Permissive Hypotension: In hemorrhagic shock from ruptured AAA, target SBP 70-90 mmHg to prevent exacerbation of bleeding while maintaining minimal vital organ perfusion
- Massive Transfusion: Activate MTP early; use balanced 1:1:1 blood product ratios; limit crystalloid to prevent dilutional coagulopathy
- Time-Critical Decisions: Unstable patients with presumed surgical emergency proceed to OR without waiting for confirmatory imaging
- Communication: Use structured approaches (SBAR) for surgical consultation; clear communication with OR, blood bank, and family is essential