What is the gold‑standard intra‑operative anesthetic plan to manage hypotension during infrarenal abdominal aortic aneurysm repair in a high‑risk male over 65 years with hypertension, coronary artery disease, peripheral vascular disease, chronic obstructive pulmonary disease, and possible renal insufficiency?

Gold Standard Intraoperative Anesthetic Plan for Hypotension During Infrarenal AAA Repair

The gold standard approach mandates maintaining mean arterial pressure (MAP) ≥60-65 mmHg or systolic blood pressure (SBP) ≥90 mmHg throughout the procedure using invasive arterial monitoring, vasopressor support (phenylephrine or norepinephrine), and comprehensive hemodynamic optimization guided by transesophageal echocardiography. 1, 2

Immediate Pre-Induction Setup

Establish invasive arterial blood pressure monitoring before induction of anesthesia to enable beat-to-beat tracking and prevent the significant hypotension that commonly occurs during induction in elderly patients with cardiovascular disease 1, 2. This allows immediate detection and treatment of hypotension before non-invasive measurements would capture it 1.

• Obtain baseline vital signs including heart rate, blood pressure, heart rhythm, SpO2, and temperature before induction 1
• Confirm patient's resuscitation status is documented 1
• Verify hemoglobin concentration and estimated glomerular filtration rate (eGFR) are available 1

Anesthetic Technique

General anesthesia with comprehensive hemodynamic monitoring is required for open infrarenal AAA repair (Class I, Level C) 2. The anesthetic agents should be selected to minimize cardiovascular depression while maintaining adequate depth 2.

• Continue perioperative beta-blocker therapy without interruption in patients with known coronary artery disease, as this is the single most evidence-based intervention to reduce perioperative cardiac mortality (Class I, Level A) 2
• Ensure adequate pre-operative hydration before induction to minimize hypotensive episodes 2

Intraoperative Monitoring Requirements

Essential Monitoring

• Transesophageal echocardiography (TEE) is reasonable for all open aortic repairs unless contraindicated (Class IIa, Level B) 2. TEE provides real-time assessment of cardiac filling, contractility, and guides fluid/vasopressor management 2
• Motor or somatosensory evoked-potential monitoring is useful when data will influence intra-operative therapeutic decisions (Class IIa, Level B) 2
• Central venous pressure monitoring may be considered, though it correlates poorly with blood volume in elderly patients with poorly compliant ventricles 1

Temperature Management

• Maintain normothermia aggressively using forced air warming and fluid warming devices, as perioperative hypothermia in elderly patients increases risk of postoperative delirium, cardiac dysfunction, prolonged hospital stay, and poor wound healing 1
• Monitor temperature continuously (tympanic/pharyngeal/oesophageal intra-operatively) 1

Hypotension Management Algorithm

Definition and Targets

Hypotension is defined as MAP <60-65 mmHg or SBP <90 mmHg, or a fall in SBP >20% from pre-induction baseline 1. The "least bad" definition for elderly patients is a fall in SBP >20% from baseline 1.

Immediate Interventions for Hypotension

Step 1: Assess and Optimize Preload

• Use TEE to assess left ventricular filling and guide fluid administration 2
• Administer isotonic crystalloid boluses cautiously, avoiding fluid overload in elderly patients with poorly compliant ventricles 1
• Consider dynamic parameters (Ea-dyn, dP/dt) if available via advanced monitoring platforms 3

Step 2: Vasopressor Support

• Phenylephrine 50-250 mcg IV bolus for immediate correction of hypotension during perioperative period 4
• Phenylephrine continuous infusion 0.5-1.4 mcg/kg/min titrated to maintain MAP ≥60-65 mmHg 4
• Norepinephrine may be preferred if cardiac output is compromised, as phenylephrine can cause reflex bradycardia and decreased cardiac output 4

Step 3: Optimize Cardiac Output

• Use TEE to assess contractility and adjust inotropic support if needed 2
• Ensure adequate depth of anesthesia without excessive cardiovascular depression 2

Critical Periods Requiring Heightened Vigilance

During Induction

• The highest risk period for severe hypotension in elderly patients with CAD 1
• Have vasopressor drawn up and ready before induction 1
• Consider reduced induction doses of anesthetic agents 1

During Aortic Cross-Clamping

• Anticipate increased afterload and potential myocardial ischemia 2
• Maintain coronary perfusion pressure with adequate MAP 2

During Aortic Unclamping

• Anticipate profound hypotension from reperfusion and vasodilation 2
• Have vasopressor infusion running and ready to increase 2
• Ensure adequate volume loading before unclamping 2

Renal Protection Strategy

Avoidance of hypotension, low cardiac output, and hypovolemia is critical because pre-operative renal dysfunction is the strongest predictor of acute renal failure after aortic surgery 2.

• Maintain MAP ≥65 mmHg to preserve renal perfusion pressure 1, 2
• Avoid nephrotoxic agents when possible 2
• Monitor urine output continuously 2

Pulmonary Considerations

• Patients with COPD require careful ventilator management to avoid auto-PEEP and hemodynamic compromise 2
• Arterial blood gas analysis should guide ventilator adjustments 2

Common Pitfalls to Avoid

• Do not allow MAP to fall below 60 mmHg, as this increases risk of myocardial injury, acute kidney injury, and stroke 1
• Do not rely on non-invasive blood pressure monitoring alone during major vascular surgery, as intermittent measurements miss hypotensive episodes 1
• Do not use permissive hypotension strategies in elderly patients with chronic hypertension and coronary artery disease, as they require higher perfusion pressures 5
• Do not induce anesthesia without adequate resuscitation if the aneurysm is ruptured, as loss of catecholamine response can cause immediate circulatory collapse 2
• Do not use central venous pressure as the sole guide for fluid management in elderly patients, as it correlates poorly with volume status 1
• Do not allow hypothermia to develop, as it significantly worsens outcomes in elderly patients 1, 5

Hypotension Prediction and Prevention

• Consider using Hypotension Prediction Index (HPI) technology if available, as recent data shows it can reduce cumulative hypotension time to <10% of surgical time during open AAA repair 3
• The HPI platform integrates advanced parameters (HPI, Ea-dyn, dP/dt) to predict hypotension before it occurs, allowing preemptive intervention 3
• Target time-weighted average for MAP <65 mmHg (TWA65) should be <0.40 mmHg 3