Related Experiment Video
Updated: Apr 19, 2026
MRI Mapping of Cerebrovascular Reactivity via Gas Inhalation Challenges
Published on: December 17, 2014
A pilot study to determine whether visually evoked hemodynamic responses are preserved in children during
Thushara Perera1, Philip M Lewis, Andrew J Davidson
1Department of Electronic Engineering, La Trobe University, Bundoora, Vic., Australia; Department of Anaesthesia and Pain Management, Murdoch Children's Research Institute, Parkville, Vic., Australia.
Insights
Near-infrared spectroscopy detected visually evoked hemodynamic responses (VEHRs) in some anesthetized children. Fentanyl administration was associated with the absence of these responses, suggesting a potential impact of anesthetics on cerebral blood flow regulation.
Area of Science:
- Anesthesiology
- Neuroscience
- Biomedical Engineering
Background:
- Anesthetic depth monitoring is challenging in young children due to developmental EEG changes.
- Flow-metabolism coupling (FMC), an increase in cerebral blood flow with metabolic demand, is a fundamental physiological response.
- The impact of anesthesia on FMC is not well understood, necessitating investigation into related hemodynamic responses.
Purpose of the Study:
- To investigate visually evoked hemodynamic responses (VEHRs) using near-infrared spectroscopy (NIRS) in children under general anesthesia.
- To explore the relationship between anesthetic agents and the presence of VEHRs.
Main Methods:
- Recruited 23 children (2-5 years) undergoing general anesthesia for minor surgery.
- Measured VEHRs using NIRS for 30 minutes, including a 5-minute baseline after induction.
- Analyzed hemoglobin concentrations (oxy-, deoxy-, total) after artifact filtration, using statistical rules and modeling to identify evoked responses.
Main Results:
- NIRS data were obtained from 20 children; 9 exhibited VEHRs, with none in baseline recordings.
- VEHRs were absent in 8 out of 10 patients who received fentanyl.
- No association was found between VEHRs and baseline control data.
Conclusions:
- VEHRs are detectable using NIRS in a subset of anesthetized children.
- Fentanyl administration was significantly associated with the absence of VEHRs.
- The underlying mechanism for fentanyl's effect on VEHRs requires further elucidation.
Background:
Anesthetic depth is an important parameter to monitor during surgery, yet remains difficult to quantify, particularly in young children where developmental changes influence the electroencephalogram. A more fundamental physiological response to stimulation is the increase in cerebral blood flow secondary to increased metabolic demand, referred to as flow-metabolism coupling (FMC) and measurable using near-infrared spectroscopy (NIRS). Little is known about the effect of anesthesia on FMC; therefore, we studied visually evoked hemodynamic responses (VEHRs) using NIRS in children undergoing general anesthesia for minor surgical procedures.
Method:
We recruited 23 children (aged 2-5 years), undergoing surgery requiring general anesthesia. VEHRs were measured for 30 min using NIRS, including 5 min of baseline recording after anesthetic induction. Parameters recorded using NIRS included the concentrations of oxygenated (oxy), deoxygenated (deoxy), and total hemoglobin (Hb), which were separated into epochs for evoked response analysis after filtration of motion artifact and baseline drift. Goodness-of-fit statistics and classification rules were used to determine the existence of evoked responses, and a modified Gaussian equation was used to model each evoked response.
Results:
Near-infrared spectroscopy data were recorded in 20/23 children, of whom nine showed a VEHR. No responses were seen in the baseline control data. When examining the relationship between VEHR and anesthetic agents, we noted that for 8/10 patients in whom preoperative or intraoperative fentanyl were administered and VEHRs were absent.
Conclusion:
We have shown that VEHRs can be detected using NIRS in some anesthetized children. Administration of fentanyl was associated with an absence of VEHRs. The mechanism underlying this association is unclear.
More Related Videos
14:52Recording Brain Electromagnetic Activity During the Administration of the Gaseous Anesthetic Agents Xenon and Nitrous Oxide in Healthy Volunteers
Published on: January 13, 2018
07:43Cavernous Nerve Stimulation and Recording of Intracavernous Pressure in a Rat
Published on: April 23, 2018
