There are different companies on the market that distribute NIRS devices for medicine-related applications. One of these brands is Medtronic, which provides appliances to the Hospital Sant Joan de Déu (Barcelona).

Why are they using NIRS at the Sant Joan de Déu paediatric Hospital? Depending on the service, they can use it to monitor the consumption of oxygen to cerebral level in the children subjected to surgical interventions (anaesthesia and resuscitation); either at the cerebral and mesenteric level (abdominal part) in the case of the newborn children (paediatrics and neonatology), not only to monitor the brain consumption of oxygen but also the peripheral.

From the conversations I had with Dr. Marta Campruví, a neonatologist at Hospital Sant Joan de Déu, questions and doubts were raised, but also solutions were found to issues that were vital in my research work. One of the questions I wanted to ask was about the use of the device in the abdominal wall (mesenterium) and the possibility of monitoring the oxygen flows to the intestinal part. Clearly, there is an important anatomical difference between the neonatal and adult mesenteric part. In order to achieve a clear criterion as to whether the wavelength of the Artinis device would be able to cross a layer of fabric larger, I realized that this type of monitoring was not viable. Therefore, it was necessary to return to the initial idea, to monitor peripheral muscle groups with fewer subcutaneous adipose tissue.

In the case of Medtronic sensors are non-reusable electrodes. Artinis has sensors that in themselves are the measuring devices: PortaMon (muscle) and PortaLite (brain). The advice of Dr. Campruví was to make a first pilot test with a small group of athletes:

  1. Choosing a viable, sensitive and sensible number for the pilot test, n = 2-3 people.
  2. Remove the hairs and clean the monitoring area.
  3. Write down the distances of the electrodes.
  4. Make 10 readings in the 3 conditions: basal, in submaximum and post-apnoea.
  5. The 3 readings (basal, submaximum and recovery) must be consecutive and without removing the sensors.
PortaLite PortaMon
Basal SUBMAXIMAL Recovery Basal SUBMAXIMAL Recovery
Start 30 min before 4 minutes? 30 min Post Start 30 minutes before 4 minutes? Start 30 minutes Post
10 1-minute readings 1 single Reading 10 1-minute readings 10 1-minute readings 1 single Reading 10 1-minute readings

Questions:

  • How do Oxyhaemoglobin and Deoxihaemoglobin evolve during Submaximum apnoea at the muscular and cerebral level?
  • What are the changes in the three conditions (basal, submaximum and recovery)?

Further research in relation to the best anatomical region to place the PortaMon (muscle) is not clear if it is necessary to be in a very distal position (arm or leg) or more proximal (pectoral or dorsal). At the same time, it will be necessary to see how the different layers of tissue affect the wavelength, because it is clear that this wavelength is sensitive to the thickness of subcutaneous adipose tissue.

Featured image extracted from the INVOS Manual: http://www.wemed1.com/downloads/dl/file/id/7947/product/10495/manual_for_mo_s_5100c.pdf