Validation of noninvasive hemoglobin analysis by spectroscopic optical coherence tomography

Quantification of total haemoglobin concentrations (tHb) is a key step in the
diagnosis of haematologic disorders. The current gold standard for this
procedure is invasive venous blood sampling, followed by laboratory analysis of
the tHb. This procedure is disadvantageous for vulnerable patient groups (e.g.
premature infants) and hampers the possibility for continuous monitoring.
We hypothesize that spectroscopic optical coherence tomography (sOCT) can
quantify the tHb in a non-invasive manner. sOCT obtains the tHb from 3D images
of the microcirculation in the skin or sublingual/sublabial tissue, by
quantifying the optical absorption of hemoglobin with low power light. In a
recent pilot non-WMO study on healthy volunteers, we demonstrated that the tHb
determined by sOCT falls within the healthy biological range. The next step -
described in this protocol - is a validation study, in which we compare the tHb
determined by sOCT to the gold standard, invasive blood sampling.

The objective of this study is to validate the tHb determined by sOCT by
comparing it to the tHb from invasive blood sampling. From this comparison, we
aim to optimize our data analysis procedure for in vivo sOCT measurements. We
also aim to determine the precision of sOCT for noninvasive tHb determination.

Observational, proof-of-concept study

The burden per participant will be restricted to a one-time sOCT measurement
session and a one-time standard invasive venous blood withdrawal procedure.
- The non-invasive sOCT measurements use low-power light, are pain free, safe
and do not interfere with the physiology of the microcirculation. During the
measurements, a steering laser beam will scan a region of interest at the skin.
Completing a scan takes ~2 minutes, in which the subject must remain in a
static, relaxed position. Multiple scans at different locations will be
acquired, demanding a total time of ~30 minutes. In this process, no mechanical
components will touch the participant and also electrical risks are absent. All
surfaces that are in contact with the participant during the sOCT measurement
will be sterilized before and after each measurement session.
- The standard venous blood withdrawal procedure will be performed at the
antecubital area (i.e. the bend of the elbow), requires 5 mL blood and takes
around 5 minutes. Blood sampling will be performed by a skilled and qualified
analyst of the TechMed Centre donor service of the University of Twente, while
adhering to the hygiene standards for blood draws (hand hygiene, skin
sterilization, sterile needles and equipment). This minimizes the risks of
pain, bleeding, fainting, bruising, infection and/or hematoma at the injection
site.
Participation in this study does not provide any direct benefit to the
participants. If the outcome of this study demonstrates that sOCT can quantify
the tHb with sufficient precision, this may eventually result in a benefit for
future patients who require a tHb determination. For those patients, a
non-invasive sOCT determination can potentially replace the current invasive
gold standard.