Hypotension, subarachnoid block and the elderly patient

Area of Science:

• Anesthesiology
• Geriatric Medicine
• Cardiovascular Physiology

Background:

• Hypotension during subarachnoid block is common in the elderly due to sympathetic nervous system blockade.
• This blockade reduces systemic vascular resistance and cardiac output, potentially abolishing cardiovascular reflexes and leading to cardiac arrest.
• Previous reports suggested cardiac output decreases, but recent findings indicate it may not, with heart rate influenced by multiple factors.

Purpose of the Study:

• To review current literature on managing hypotension in elderly patients undergoing subarachnoid block.
• To identify effective strategies for preventing and treating hypotension in this demographic.
• To evaluate the efficacy of different vasopressor agents.

Main Methods:

• Literature review of studies on subarachnoid block and hypotension in the elderly.
• Analysis of physiological changes, including blood pressure, systemic vascular resistance, cardiac output, and heart rate.
• Evaluation of fluid management and vasopressor treatment strategies.

Main Results:

• Adequate intravenous fluid preloading (approx. 8 ml.kg-1) is crucial for maintaining cardiac output and preventing cardiac arrest.
• Head-down tilt can be beneficial in maintaining preload.
• If systolic arterial pressure drops >25% or below 90 mmHg, vasopressor treatment is indicated; alpha-adrenoceptor agonists are preferred over ephedrine due to better vasoconstriction and inotropic effects in the elderly.

Conclusions:

• Maintaining adequate preload with intravenous fluids is key to managing hypotension during subarachnoid block in the elderly.
• Alpha-adrenoceptor agonists represent a more logical vasopressor choice for this population compared to ephedrine.
• Careful monitoring and timely intervention are essential to prevent adverse cardiovascular events.