[The spread of thoracic epidural anesthesia]

Area of Science:

• Anesthesiology
• Pharmacology

Context:

• Epidural anesthesia is crucial for surgical procedures.
• Assessing the spread of anesthetic block is vital for patient safety and efficacy.
• Test doses are commonly used to predict block spread.

Purpose:

• To evaluate the effectiveness of a 2% lidocaine test dose for early detection of epidural anesthesia spread.
• To determine reliable clinical signs for monitoring the extent of sympathetic block.
• To assess if the sympathetic block induced by the test dose is sufficient to cause circulatory changes.

Summary:

• The study investigated the spread of a 2% lidocaine test dose in 40 patients undergoing surgery with continuous epidural anesthesia.
• Block levels were assessed using skin vasodilatation, loss of goose flesh reflex, and sensory loss (cold, pin-prick).
• Loss of goose flesh reflex extended to 7.7 +/- 2.2 dermatomes with 2 ml and 14.1 +/- 4.3 dermatomes with 5 ml of 2% lidocaine, indicating an incomplete but extensive sympathetic block.

Impact:

• Loss of goose flesh reflex and skin vasodilatation are identified as the most reliable objective signs for early detection of sympathetic block spread.
• The sympathetic block achieved by the test dose, while extensive, was insufficient to induce significant circulatory changes.
• Findings contribute to optimizing epidural anesthesia monitoring techniques.