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Effect of conscious sedation on cardiac autonomic regulation during colonoscopy
M Ristikankare1, R Julkunen, T Laitinen
1Dept. of Medicine, Kuopio University Hospital, Finland.
Insights
Conscious sedation with midazolam during colonoscopy amplifies sympathetic nervous system activity, potentially increasing cardiovascular event risk. This study highlights midazolam
Area of Science:
- Cardiology
- Autonomic Nervous System Regulation
- Gastroenterology
Background:
- Colonoscopy is linked to cardiovascular events like hypotension and myocardial ischemia.
- The autonomic nervous system's role in these events is suspected.
- Conscious sedation is commonly used during colonoscopy.
Purpose of the Study:
- To investigate the impact of conscious sedation on cardiac autonomic regulation during colonoscopy.
- To compare the effects of midazolam sedation versus placebo and no sedation.
Main Methods:
- 180 patients undergoing colonoscopy were randomized into midazolam, placebo, or control groups.
- Continuous electrocardiogram monitoring was performed.
- Heart rate variability (HRV) was analyzed using power spectral analysis (LF and HF components).
Main Results:
- Colonoscope intubation increased low-frequency (LF) HRV and decreased high-frequency (HF) power in all groups.
- The LF/HF ratio, indicating sympathetic regulation, increased in midazolam and placebo groups.
- Midazolam sedation led to significantly higher LF and lower HF power, and a higher LF/HF ratio compared to placebo and control groups.
Conclusions:
- Midazolam sedation potentiates sympathetic nervous system dominance during colonoscopy.
- Conscious sedation with midazolam may increase the risk of cardiovascular events.
- Understanding these effects is crucial for patient safety during endoscopic procedures.
Background:
Colonoscopy is associated with cardiovascular events including hypotension, hypertension, and myocardial ischemia. The pathogenetic mechanisms of these cardiovascular events are unknown, but there is evidence that the autonomic nervous system may play a role. Conscious sedation is often used to relieve the inconvenience caused by the procedure. In this study, we evaluated the effects of sedation on cardiac autonomic regulation during colonoscopy.
Methods:
One hundred and eighty patients undergoing elective colonoscopy were prospectively randomized into three groups: (i) sedation with intravenous midazolam (midazolam group); (ii) sedation with intravenous saline (placebo group); and (iii) no intravenous cannula (control group). Continuous electrocardiogram was recorded prior to, during, and after the colonoscopic procedure. Heart rate variability (HRV) was assessed by means of the power spectral analysis; the powers of low-frequency (LF 0.04-0.15 Hz) and high-frequency (HF 0.15-0.40 Hz) components were calculated.
Results:
Intubation of the colonoscope increased the LF component of HRV and decreased HF power in all study groups compared to baseline recording. Furthermore, compared to baseline, the LF/HF ratio--a marker of cardiac sympathetic regulation--increased during intubation in the midazolam (P < 0.001) and placebo (P < 0.05) groups, with no change in the control group. During intubation the midazolam group presented with higher LF and lower HF power than placebo (P < 0.001) and control groups (P < 0.01). Accordingly, the LF/HF ratio was higher in the midazolam group than in the placebo (P < 0.05) or control groups (P < 0.05).
Conclusions:
Midazolam potentiates the dominance of the sympathetic nervous system induced by colonoscopy. Therefore, conscious sedation with midazolam may contribute to the occurrence of cardiovascular events during colonoscopy.