P003: PERIOPERATIVE MANAGEMENT FOR HEMODYNAMIC STABILITY OF AN UNEVEN THORACIC ABDOMINAL ANEURYSM
Garfield W Bloodman III, Medical Student
American university of Antigua
Introduction: A symptomatic or incidental thoracic aortic aneurysm (TAA) can turn any anesthetic surgery into a critical hemodynamic challenge. The acute elevation of the mean arterial pressure (MAP) and the rate of pressure is the biggest physiological concern for the case of this 67-year-old male patient with TAA. Using the Law of Laplace, to better understand the hemodynamics of the aneurysm, (T= P x r/2h) the radius of the vessel and pressure directly correlates to the wall stress being exerted. In this patient, the wall stress is being distributed unevenly since there is an asymmetrical aneurysm of (4.7 cm x 3.9 cm), this disproportion increases the risk of dissection of the aorta during a hypertensive surge. This presentation assesses the perioperative protocols required to prevent aneurysm rupture during surgery by maintaining a meticulous hemodynamic stability.
Methods: For the 67-year-old man with the 4.7x 3.9 cm TAA a management first approach was developed. The theoretical anesthetic plan was structured into a bundle primarily focusing on hemodynamic protecting of the aorta from surgical stress:
1. Continuous Biofeedback Monitoring: beat to beat continuous pressure monitoring by placing a pre-induction radial arterial line that can detect rapid changes and fluctuations that are missed by noninvasive cuffs.
2. Weakening the sympathetic: the administration of etomidate and a short acting beta blocker, esmolol, being titrated for the purpose of weakening the effects of catecholamine surge that happens during endotracheal intubation.
3. Tight control on systemic vascular resistance: Maintaining anesthesia and minimizing the volatile gas effect on SVR by using total intravenous anesthesia prevents the oscillation between vasoconstriction and vasodilation that can happen with volatile gases.
Results: The focus of this theoretical protocol is to maintain a narrow therapeutic corridor for the MAP. The 4.7 cm dilated segment is prevented from reaching its breaking point, by using the maximum rate of pressure change with time (dP/dt), by theoretically suppressing the sympathetic stress response of intubation. To prevent the Valsalva-induced pressure increase, while extubating of the patient, a soft emergence strategy is implemented by using intravenous lidocaine to prevent coughing.
Discussion/ Conclusion: The reduction of wall stress is prioritized over the typical standard anesthetic speed for the perioperative management for a TAA. This case focuses on hemodynamic stability, which is foremost achieved through invasive monitoring and proactively suppressing the sympathetic nervous system’s response to stress by way of:
- Clinical decision of A-line first: To be able to monitor physiological stress of induction.
- dP/dt Control: To manage the force with which blood hits the wall of the aneurysm, making the contractility of the heart and heart rate control as vital as MAP control.
- Clinical bundle: Implementing a structure evidenced based practice "TAA Bundle" to ensures that symptomatic or incidental vascular pathologies are managed using safety margins.
Ct scans of the TAA are available, but the system would not let me submit them.