Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
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The ability to continuously monitor cardiovascular function is a fundamental tool in both the clinical assessment of the ill patient and in the examination of the pharmacological properties of various drugs. Continuous measurement of heart rate is readily achieved, but traditional methods of monitoring arterial pressure and cardiac output have involved arterial and venous catheterisation to achieve recordings.

Arterial pressure monitoring entails the insertion of a cannula into the radial artery using a local anaesthetic. Complications include pain, haemorrhage and arterial damage (Slogoff et al., 1983). Cardiac output is measured by right heart catheterisation using dye-dilution or thermodilution methods. Complications include infection, arrhythmias, endocarditis, pneumo- and haemothorax and cardiac or pulmonary artery puncture (Hirschl et al., 1997). Therefore, attempts have been made to non-invasively monitor arterial pressure and cardiac output.

Arterial pressure can be continuously monitored using the newly developed finger blood pressure monitor (Portapres). Cardiac output can be non-invasively measured using quantitative Doppler echocardiography, impedance cardiography (ICG) and the finger blood pressure monitor, with only the latter two being suitable for continuous monitoring. All three methods estimate stroke volume and calculate cardiac output using the heart rate.

The Portapres finger blood pressure monitor therefore offers the opportunity to simply and continuously measure the heart rate, mean arterial pressure and cardiac output which, if accurate, would be extremely useful. ICG is well established as a method of non-invasively monitoring cardiac output and has been extensively compared with invasive techniques with encouraging results (Woltjer et al., 1997 ).

This study is designed to evaluate the Portapres as a continuous monitor of cardiovascular function, by comparison with the established non-invasive techniques of sphygmomanometry and ICG. Healthy subjects were monitored at rest and over a range of graded treadmill exercise. In addition the equipment was assessed for reproducibility and ease of use.

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