Heart rate variability and the prone position under general versus spinal anesthesia

Area of Science:

• Anesthesiology
• Autonomic Nervous System Physiology
• Cardiovascular Regulation

Background:

• The prone position during surgery can impact cardiovascular stability.
• Heart rate variability (HRV) analysis, particularly power spectral analysis, offers insights into autonomic nervous system (ANS) function.
• Understanding ANS responses to different anesthetic techniques in the prone position is crucial for patient safety.

Purpose of the Study:

• To evaluate heart rate (HR) variability using power spectral heart rate (PSHR) analysis in patients positioned prone.
• To compare the effects of spinal anesthesia versus general anesthesia on HRV and blood pressure (BP) in the prone position.

Main Methods:

• Prospective clinical study involving 20 healthy patients undergoing elective lumbar spine surgery.
• Patients received either spinal or general anesthesia.
• PSHR, HR, and BP were measured at baseline and after achieving a stable prone position.

Main Results:

• The prone position increased HR in the spinal anesthesia group and decreased BP in the general anesthesia group.
• Low-frequency activity (LFa) and the LFa/HFa ratio remained unchanged in the spinal group but decreased significantly in the general anesthesia group.
• Spinal anesthesia (T8.7) was associated with less change in LFa and preserved BP.

Conclusions:

• Low spinal anesthesia appears to better preserve autonomic nervous system compensatory mechanisms in the prone position compared to general anesthesia.
• This preservation is evidenced by stable LFa and maintained BP, suggesting a potentially safer anesthetic approach for prone spinal surgery.