What medications and peri‑operative interventions should be administered before aortic cross‑clamping in an adult undergoing open aortic repair?

Medications and Interventions Prior to Aortic Cross-Clamping

Before aortic cross-clamping in open aortic repair, administer surgical antibiotic prophylaxis before skin incision, optimize volume status with pre-operative hydration, establish invasive arterial monitoring and large-bore IV access, and in acute dissection cases start intravenous beta-blockade (esmolol) targeting heart rate ≤60 bpm before any vasodilator therapy. 1, 2

Infection Prophylaxis

• Administer surgical antibiotic prophylaxis before skin incision to reduce wound infection and endocarditis risk, which ranges from 1-5% when timing is inadequate. 1

Hemodynamic Control

For Acute Aortic Dissection

• Start intravenous esmolol immediately to achieve heart rate ≤60 bpm before administering any vasodilator; this reduces aortic wall shear stress by lowering left ventricular ejection force (Class I recommendation). 1, 2
• Esmolol's ultra-short half-life (5-15 minutes) permits rapid titration and is the preferred agent. 1
• Target systolic blood pressure of 100-120 mmHg after achieving heart rate control. 1, 2
• Add sodium nitroprusside only after adequate heart-rate control if systolic BP remains >120 mmHg; alternatives include nicardipine or clevidipine (Class I for use after beta-blockade). 1
• Never administer vasodilators before beta-blockade in aortic dissection—this practice is harmful and may exacerbate the dissection (Class III harm). 1, 2

For Non-Dissection Cases

• Establish invasive arterial line placement (preferably right radial) before cross-clamping for continuous accurate blood pressure monitoring (Class I). 1
• Bilateral arm pressures are advised to exclude pseudo-hypotension from arch branch obstruction. 1

Volume and Renal Protection

• Optimize pre-operative volume status with adequate hydration before cross-clamping to preserve renal function (Class IIb recommendation). 1, 3
• Avoid volume depletion before cross-clamping; underfilled ventricles can precipitate rapid hemodynamic deterioration, especially in patients with severe left ventricular hypertrophy (Class I). 1
• Do not use furosemide, mannitol (when used solely for renal protection), or dopamine for renal protection during aortic surgery—these carry a Class III (harm) recommendation as they have not demonstrated benefit. 1, 3

Spinal Cord Protection

• Consider methylprednisolone 30 mg/kg both before and after aortic occlusion to lessen spinal cord edema and enhance free-radical scavenging, especially in thoraco-abdominal aortic repairs where ischemia risk is highest (Class IIb recommendation). 1
• Mannitol 0.25-1.0 g/kg may be considered before cross-clamping to modulate ischemic spinal cord injury by reducing edema (Class IIb), but it carries a Class III recommendation when used solely for renal protection. 1

Temperature Management

• Induce moderate systemic hypothermia (≈32°C) before cross-clamping in thoracic aortic aneurysm surgery, as it is associated with improved outcomes and is generally well tolerated in patients not on full cardiopulmonary bypass (Class IIa recommendation). 1
• Excessive hypothermia can precipitate atrial or ventricular fibrillation, so monitor carefully. 1

Monitoring Requirements

• Establish at least one large-volume IV line (peripheral or central) prior to cross-clamping (Class I). 1
• Ensure immediate defibrillator access with pre-applied pads before cross-clamping (Class I). 1
• Invasive arterial monitoring is mandatory for continuous blood pressure assessment during the procedure. 1

Critical Pitfalls to Avoid

• Never start vasodilators before beta-blockade in aortic dissection—this can worsen the dissection through reflex tachycardia (Class III harm). 1, 2
• Do not rely on dopamine, furosemide, or mannitol for renal protection—they lack supporting evidence and carry Class III recommendations against such use. 1, 3
• Avoid nephrotoxic medications in the peri-operative period, especially aminoglycosides and NSAIDs, to reduce acute kidney injury risk. 3
• Do not proceed with inadequate volume resuscitation—hypovolemia before cross-clamping dramatically increases hemodynamic instability risk. 1

Additional Considerations

• Minimize planned cross-clamp time: durations <15 minutes carry minimal risk, whereas times >40-60 minutes markedly increase the risk of renal and spinal cord injury. 3
• Sodium nitroprusside at doses >5 µg/kg/min decreases spinal cord perfusion pressure by increasing cerebrospinal fluid pressure and decreasing blood pressure distal to the aortic cross-clamp. 4
• Mannitol infusion significantly increases central venous pressure, pulmonary capillary wedge pressure, and cerebrospinal fluid pressure, which may affect spinal cord perfusion. 5