Long-term pressure monitoring with arterial applanation tonometry: A non-invasive alternative during clinical intervention?

School of Engineering and Design, Brunel University, London, UK.
Technology and health care: official journal of the European Society for Engineering and Medicine (Impact Factor: 0.7). 01/2008; 16(3):183-93.
Source: PubMed


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.

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Available from: Michel MRF Struys,
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    • "Pressman and Newgard (1963) rediscovered the sphygmogram by using the technique of applanation tonometry to measure arterial pressure wave shapes in 1963. It is the basis of the widely used type of transducers for accurate, non-invasive detection of peripheral arterial pressure wave shape (Matthys et al 2008, McEniery et al 2008). Penaz (1973) later introduced the vascular unloading method of measuring continuous blood pressure and its contour non-invasively in the finger using the photoplethysmographic technique. "
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