Affiliations: [a] School of Engineering and Design, Brunel University, London, UK | [b] Department of Anaesthesia, Ghent University Hospital, Ghent, Belgium | [c] Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia | [d] Institute Biomedical Technology IBiTech, Ghent University, Ghent, Belgium
Correspondence:
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Address for correspondence: Dr. Koen S. Matthys, Brunel University West London, School of Engineering and Design, 1st Floor Howell Bld, Room H124, Uxbridge, Middlesex, UB8 3PH, UK. Tel.: +44 1895 267486; Fax: +44 1895 256392; E-mail: koen.matthys@brunel.ac.uk.
Abstract: Arterial tonometry is a non-invasive technique for continuous registration of arterial pressure waveforms. This study aims to assess tonometric blood pressure recording (TBP) as an alternative for invasive long-term bedside monitoring. A prospective study was set up where patients undergoing neurosurgical intervention were subjected to both invasive (IBP) and non-invasive (TBP) blood pressure monitoring during the entire procedure. A single-element tonometric pressure transducer was used to better investigate different inherent error sources of TBP measurement. A total of 5.7 hours of combined IBP and TBP were recorded from three patients. Although TBP performed fairly well as an alternative for IBP in steady state scenarios and some short-term variations, it could not detect relevant long-term pressure variations at all times. These findings are discussed in comparison to existing work. Physiological alterations at the site of TBP measurement are highlighted as a potentially important source of artifacts. It is concluded that at this point arterial tonometry remains not enough understood for long-term use during a delicate operative procedure. Physiological changes at the TBP measurement site deserve further investigation before tonometry technology is to be considered as an non-invasive alternative for long-term clinical monitoring.
