Haemoglobin dilution from epidural-induced hypotension with and without fluid loading

Area of Science:

• Anesthesiology
• Cardiovascular Physiology
• Geriatric Medicine

Background:

• Lumbar epidural anesthesia can cause significant hemodynamic changes, including hypotension.
• Understanding blood volume dynamics is crucial for managing anesthesia-induced complications in elderly patients.
• The role of crystalloid fluid loading in mitigating these changes requires further investigation.

Purpose of the Study:

• To investigate the effect of crystalloid volume loading on blood haemoglobin concentration (B-Hb) during the onset of lumbar epidural anesthesia.
• To compare B-Hb changes in elderly men who developed hypotension versus those who maintained normal arterial pressure.
• To assess the impact of fluid loading on blood volume changes in the context of epidural anesthesia.

Main Methods:

• Ninety elderly men undergoing lumbar epidural anesthesia were studied.
• Blood haemoglobin concentration (B-Hb) was measured repeatedly to assess blood dilution or concentration.
• Participants received crystalloid volume loading (10 ml.kg-1 b.w.) or no fluid loading (control group).
• Anesthesia was induced using plain mepivacaine or mepivacaine plus adrenaline.

Main Results:

• A significant decrease in B-Hb was observed in patients who developed hypotension after crystalloid volume loading (P < 0.001).
• This decrease in B-Hb was approximately twice as great in hypotensive patients compared to those with normal arterial pressure.
• No consistent change in haemoglobin level was noted in the control group without fluid loading, regardless of blood pressure response.
• These findings were consistent with both plain mepivacaine and mepivacaine plus adrenaline anesthesia.

Conclusions:

• Crystalloid fluid loading appears to facilitate an increase in blood volume during hypotension induced by epidural anesthesia.
• The observed dilution of blood haemoglobin suggests that fluid administration can counteract or compensate for volume shifts.
• These findings highlight the importance of fluid management in preventing or managing hypotension during epidural anesthesia in elderly men.