Sympathovagal balance fluctuates during colonoscopy

Area of Science:

• Gastroenterology
• Cardiology
• Anesthesiology

Background:

• Colonoscopy is a common procedure with potential side effects including pain and cardiovascular complications.
• Heart rate variability (HRV) reflects autonomic nervous system activity during procedures.
• Understanding HRV changes during colonoscopy is crucial for patient safety.

Purpose of the Study:

• To compare heart rate variability (HRV) components during colonoscopy under three conditions: no sedation, analgesia/sedation, and total intravenous anesthesia.
• To investigate the impact of sedation and anesthesia on autonomic responses during colonoscopy.

Main Methods:

• 37 patients were randomized into three groups: no sedation, analgesia/sedation, or total intravenous anesthesia.
• Continuous Holter electrocardiography was used to monitor heart rate.
• Frequency domain analysis estimated low-frequency (LF) and high-frequency (HF) HRV components, expressed in normalized units (nu).

Main Results:

• Patients receiving analgesia/sedation or total intravenous anesthesia showed significantly lower HFnu and higher LFnu compared to the no-sedation group throughout the procedure.
• Significant differences in HRV components and LF/HF ratio were observed as the colonoscope advanced, particularly at the splenic flexure.
• Total intravenous anesthesia group exhibited a substantial increase (over 136%) in LF/HF ratio at the sigmoid flexure.

Conclusions:

• Colonoscopy, especially of the left colon, induces significant changes in heart rate variability.
• Analgesia/sedation and total intravenous anesthesia modulate HRV by increasing the low-frequency component, suggesting a shift in autonomic balance.
• These findings highlight the physiological impact of sedation and anesthesia on cardiovascular regulation during colonoscopy.