From the Guidelines
Patients with a 5 cm thoracic aortic aneurysm are at high risk of aneurysm rupture or dissection during general anesthesia due to hemodynamic fluctuations, and strict blood pressure control is essential to minimize this risk. The primary concerns include aneurysm rupture or dissection due to hemodynamic fluctuations, particularly during induction, intubation, and emergence phases when blood pressure can spike dramatically. According to the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1, aneurysms of ≥5.0 cm would be expected to have a greater risk of complications or rapid growth than would smaller aneurysms. Maintaining strict blood pressure control is essential, with systolic pressure typically kept below 120 mmHg using medications like esmolol (50-300 mcg/kg/min), labetalol (5-20 mg IV boluses), or nicardipine (2-15 mg/hr). Avoiding tachycardia is equally important as it increases aortic wall stress.
Some key considerations for anesthesia management in these patients include:
- Careful airway management to minimize sympathetic stimulation, often requiring deeper anesthesia during intubation with additional doses of propofol (20-30 mg) or fentanyl (50-100 mcg)
- Invasive arterial monitoring to allow beat-to-beat blood pressure management
- Adequate premedication with anxiolytics like midazolam (1-2 mg IV) to reduce anxiety-induced hypertension
- Selection of anesthetic technique dependent on the planned surgical interventions and the patient’s comorbid conditions, as outlined in the 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease 1
It's also important to note that the indications for prophylactic aortic surgery have been outlined in recent recommendations, including a diameter of 5.0 cm for bicuspid aortic valve with risk of dissection or low surgical risk at an established center 1. However, the primary focus for patients with a 5 cm thoracic aortic aneurysm undergoing general anesthesia should be on minimizing the risk of aneurysm rupture or dissection through careful blood pressure control and anesthesia management.
From the Research
General Anesthesia Risks for Thoracic Aortic Aneurysm
The risks associated with general anesthesia for a patient with a 5 cm thoracic aortic aneurysm include:
- Significant morbidity and mortality due to the complex nature of the condition and its management in the perioperative setting 2
- Catastrophic complications, such as rupture, which can be life-threatening 3
- Hemodynamic instability and cardiopulmonary complications, which can be minimized with the use of regional anesthesia or monitored anesthesia care (MAC) with local anesthetic infiltrated at the incision site 4
Anesthetic Management Considerations
Anesthetic management of thoracic aortic aneurysm repair poses several challenges, including:
- One-lung ventilation, invasive hemodynamic monitoring, left-heart bypass, massive transfusion, selective renal and visceral perfusion, and central nervous system monitoring with CSF drainage 5
- The choice of anesthetic technique, which may depend on the patient's co-existing diseases and the surgeon's familiarity with the procedure 4
Comparison of Local and General Anesthesia
A study comparing local or regional anesthesia (LRA) to general anesthesia (GA) in patients undergoing thoracic endovascular aortic repair (TEVAR) found that:
- LRA was associated with lower odds of postoperative congestive heart failure, decreased length of intensive care unit and hospital length of stay, and similar operative outcomes and long-term survival compared to GA 6
- Patients who received LRA were older and more comorbid compared to those who received GA, but still experienced shorter intensive care unit and postoperative lengths of stay 6