Diffuse optical tomography system for acute traumatic brain injury in the intensive care unit: a prospective study on...

Invasive neuromonitoring hinders the application of diffuse optical tomography (DOT) to critically ill adults in the intensive care unit (ICU).

We aim to develop and test a method for DOT recordings suitable for traumatic brain injury (TBI) patients in the ICU. This method is based on measurements and coregistration using a 3D optical scan and the acquisition of optical data using a custom-made helmet, which would enable a multimodal (invasive and noninvasive) neuromonitoring.

Coregistration accuracy between the method based on a 3D optical scan and one based on an electromagnetic digitization, the latter considered to be the gold standard, was assessed. The capacity to isolate and monitor, using functional near-infrared spectroscopy, the optical signal in the intracranial (ICT), and extracranial tissues (ECT), was tested on 23 healthy volunteers. Participants were scanned with a frequency-domain NIRS device (690 and 830 nm) during 5 Valsalva maneuvers (VM) in a simulated ICU environment.

The results showed an average error of coregistration of 5.5 mm and a sufficient capacity to isolate oxyhemoglobin ( $O_2\mathrm{Hb}$ ) ( $p=6.4·{10}^{-6}$ ) and total hemoglobin (HbT) ( $p=2.8·{10}^{-5}$ ) in the ICT from the ECT and to follow the changes of hemoglobin in the ICT during the VM ( $O_2\mathrm{Hb}$ , $p=9.2·{10}^{-4}$ ; HbT, $p=1.0·{10}^{-3}$ ).

The developed approach appears to be suitable for use on TBI patients in the ICU in a multimodal monitoring.