How do you manage hypotension in a patient with a bleeding abdominal aortic aneurysm?

Management of Hypotension in Bleeding Abdominal Aortic Aneurysm

In a patient with a bleeding abdominal aortic aneurysm, maintain permissive hypotension with a target systolic blood pressure of 80-100 mmHg using judicious fluid resuscitation, and proceed immediately to definitive surgical or endovascular repair, as hypotension or shock mandates urgent operative intervention. 1

Initial Resuscitation Strategy

Target a systolic blood pressure of 80-100 mmHg until hemorrhage control is achieved. 1 This permissive hypotension strategy prevents:

• Clot dislodgement from increased hydrostatic pressure 1
• Dilutional coagulopathy from excessive crystalloid administration 1
• Hypothermia-induced coagulopathy 1
• Exacerbation of bleeding from rapid blood pressure increases 1

The 2022 ACC/AHA guidelines specifically state that permissive hypotension (maintaining systolic blood pressure between 60-90 mmHg to preserve mentation) can be beneficial to decrease the rate of bleeding in ruptured AAA. 1

Fluid Administration Approach

Begin with cautious volume administration titrated to blood pressure improvement as the first-line approach. 1

• Establish large-bore IV access for fluid and blood product administration 2
• Administer crystalloids (0.9% sodium chloride or balanced crystalloid solution) targeting mean arterial pressure >65 mmHg 1
• Avoid aggressive fluid resuscitation: Large-volume crystalloid administration (>2000 mL) increases coagulopathy risk to >40%, and >4000 mL increases risk to >70% 1
• Transfuse packed red blood cells when hemoglobin drops below 7 g/dL, targeting 7-9 g/dL 1

Vasopressor Use When Fluid Resuscitation Fails

If permissive hypotension strategy fails to maintain systolic blood pressure >80 mmHg despite restricted fluid resuscitation, add norepinephrine to maintain adequate perfusion. 1, 3

• Norepinephrine is the recommended vasopressor for trauma-related hemorrhagic shock when fluid resuscitation alone is insufficient 1
• Critical caveat: Vasopressors have the potential to cause further false lumen propagation in aortic pathology 1
• Avoid inotropic agents (dobutamine, epinephrine) as they increase the force and rate of ventricular contraction, thereby increasing shear stress on the aortic wall and potentially worsening bleeding 1
• Norepinephrine dosing: Start at 2-3 mL/minute (8-12 mcg/minute) of a 4 mcg/mL solution, then titrate to maintain systolic blood pressure 80-100 mmHg 3

Immediate Definitive Management

Hypotension or shock in the setting of ruptured AAA mandates immediate operative intervention. 1

For Hemodynamically Stable Patients:

• Obtain CT imaging to evaluate whether the AAA is amenable to endovascular repair 1
• Endovascular repair (EVAR) is preferred over open repair when anatomy is suitable, reducing 30-day mortality from 34% to 21% 1
• Use local anesthesia rather than general anesthesia for EVAR to reduce perioperative mortality (adjusted OR 0.27) 1

For Hemodynamically Unstable Patients:

• Transport directly to the operating room without delay for imaging 1
• Consider endovascular balloon occlusion under fluoroscopy to reduce excessive bleeding as a bridging maneuver 1
• Severely hypotensive patients (mean arterial pressure <65 mmHg requiring vasopressors) have 61% 30-day survival versus 85% for moderately hypotensive patients 4

Critical Pitfalls to Avoid

Do not aggressively resuscitate to normotensive blood pressures before hemorrhage control. 1 This traditional approach:

• Increases hydrostatic pressure causing clot disruption 1
• Dilutes coagulation factors and platelets 1
• Causes hypothermia inhibiting clotting enzyme activity 1
• Creates the "lethal triad" of hypothermia, acidemia, and coagulopathy 5

Do not delay operative intervention while attempting medical stabilization. 1 Hypotension in ruptured AAA suggests contained rupture into adjacent structures (pleural space or mediastinum) or hemopericardium, all requiring immediate surgical management. 1

Do not use pericardiocentesis for dissection-related hemopericardium except as a last resort. 1 This has been associated with recurrent pericardial bleeding and mortality; only withdraw enough fluid to restore perfusion if the patient cannot survive until surgery. 1