fNIRS brain measures of ongoing nociception during surgical incisions under anesthesia

Machines, mathematics, and modules: the potential to provide real-time metrics for pain under anesthesia

The brain-based assessments under anesthesia have provided the ability to evaluate pain/nociception during surgery and the potential to prevent long-term evolution of chronic pain. Prior studies have shown that the functional near-infrared spectroscopy (fNIRS)-measured changes in cortical regions such as the primary somatosensory and the polar frontal cortices show consistent response to evoked and ongoing pain in awake, sedated, and anesthetized patients. We take this basic approach and integrate it into a potential framework that could provide real-time measures of pain/nociception during the peri-surgical period. This application could have significant implications for providing analgesia during surgery, a practice that currently lacks quantitative evidence to guide patient tailored pain management. Through a simple readout of "pain" or "no pain," the proposed system could diminish or eliminate levels of intraoperative, early post-operative, and potentially, the transition to chronic post-surgical pain. The system, when validated, could also be applied to measures of analgesic efficacy in the clinic.

Functional near-infrared spectroscopy guided mapping of frontal cortex, a novel modality for assessing emergence delirium in children: A prospective observational study

INTRODUCTION

Despite an 18%-30% prevalence, there is no consensus regarding pathogenesis of emergence delirium after anesthesia in children. Functional near-infrared spectroscopy (fNIRS) is an optical neuroimaging modality that relies on blood oxygen level-dependent response, translating to a mean increase in oxyhemoglobin and a decrease in deoxyhemoglobin. We aimed to correlate the emergence delirium in the postoperative period with the changes in the frontal cortex utilizing fNIRS reading primarily and also with blood glucose, serum electrolytes, and preoperative anxiety scores.

METHODS

A total of 145 ASA I and II children aged 2-5 years, undergoing ocular examination under anesthesia, were recruited by recording the modified Yale Preoperative Anxiety Score after acquiring the Institute Ethics Committee approval and written informed parental consent. Induction and maintenance were done with O2, N2O, and Sevoflurane. The emergence delirium was assessed using the PAED score in the postoperative period. The frontal cortex fNIRS recordings were taken throughout anesthesia.

RESULTS

A total of 59 children (40.7%) had emergence delirium. The ED+ group had a significant activation left superior frontal cortex (t = 2.26E+00; p = .02) and right middle frontal cortex (t = 2.27E+00; p = .02) during induction, significant depression in the left middle frontal (t = -2.22E+00; p = .02), left superior frontal and bilateral medial (t = -3.01E+00; p = .003), right superior frontal and bilateral medial (t = -2.44E+00; p = .015), bilateral medial and superior (t = -3.03E+00; p = .003), and right middle frontal cortex (t = -2.90E+00; p = .004) during the combined phase of maintenance, and significant activation in cortical activity in the left superior frontal cortex (t = 2.01E+00; p = .0047) during the emergence in comparison with the ED- group.

CONCLUSION

There is significant difference in the change in oxyhemoglobin concentration during induction, maintenance, and emergence in specific frontal brain regions between children with and without emergence delirium.

Comparison of cerebral metabolic rate of oxygen, blood flow, and bispectral index under general anesthesia

SIGNIFICANCE

The optical measurement of cerebral oxygen metabolism was evaluated.

AIM

Compare optically derived cerebral signals to the electroencephalographic bispectral index (BIS) sensors to monitor propofol-induced anesthesia during surgery.

APPROACH

Relative cerebral metabolic rate of oxygen ( rCMRO 2 ) and blood flow (rCBF) were measured by time-resolved and diffuse correlation spectroscopies. Changes were tested against the relative BIS (rBIS) ones. The synchronism in the changes was also assessed by the R-Pearson correlation.

RESULTS

In 23 measurements, optically derived signals showed significant changes in agreement with rBIS: during propofol induction, rBIS decreased by 67% [interquartile ranges (IQR) 62% to 71%], rCMRO 2 by 33% (IQR 18% to 46%), and rCBF by 28% (IQR 10% to 37%). During recovery, a significant increase was observed for rBIS (48%, IQR 38% to 55%), rCMRO 2 (29%, IQR 17% to 39%), and rCBF (30%, IQR 10% to 44%). The significance and direction of the changes subject-by-subject were tested: the coupling between the rBIS, rCMRO 2 , and rCBF was witnessed in the majority of the cases (14/18 and 12/18 for rCBF and 19/21 and 13/18 for rCMRO 2 in the initial and final part, respectively). These changes were also correlated in time ( R > 0.69 to R = 1 , p - values < 0.05 ).

CONCLUSIONS

Optics can reliably monitor rCMRO 2 in such conditions.

The missing mechanistic link: Improving behavioral treatment efficacy for pediatric chronic pain

Pediatric chronic pain is a significant global issue, with biopsychosocial factors contributing to the complexity of the condition. Studies have explored behavioral treatments for pediatric chronic pain, but these treatments have mixed efficacy for improving functional and psychological outcomes. Furthermore, the literature lacks an understanding of the biobehavioral mechanisms contributing to pediatric chronic pain treatment response. In this mini review, we focus on how neuroimaging has been used to identify biobehavioral mechanisms of different conditions and how this modality can be used in mechanistic clinical trials to identify markers of treatment response for pediatric chronic pain. We propose that mechanistic clinical trials, utilizing neuroimaging, are warranted to investigate how to optimize the efficacy of behavioral treatments for pediatric chronic pain patients across pain types and ages.