Vascular Unloading Method - Continuous Blood Pressure Monitoring Methods
Saturday, Dec 22 2007
The vascular unloading method, initially described by Penaz (1973), involves obtaining estimates of blood pressure from a small pressurized cuff positioned over a finger in conjunction with a photoplethysmograph. One such apparatus, called the Finger Arterial Pressure System or FINAPRES™, monitors blood flow into the finger and provides continuous information to a mechanism that automatically adjusts air pressure in the cuff to maintain a stable partial blood flow through the artery in the finger.
Blood flow oscillations are sensed by the encircling finger cuff and translated into beat-by-beat estimates of blood pressure. Although this device may become uncomfortable during extended measurement periods, it can be used to measure blood pressure continuously for a few hours, and the ambulatory version, which alternates blood pressure determinations between two integrated finger cuffs, has been used for periods as long as 24hours (Imholz et al., 1993).
Naturally, whenever a new method for assessing blood pressure is developed, it is important to validate it with established measurement strategies. In some studies of this type, blood pressure values obtained from the devices using the vascular unloading principle have been shown to compare favorably with intra-arterial measures of blood pressure (Imholz et al., 1990; Parati et al., 1989) as well as intermittent noninvasive measures (Dorlas et al., 1985; Pace and East, 1991).
However, other studies have reported that indices of blood pressure from these devices either overestimated (Epstein et al., 1989; Kurki et al., 1989) or underestimated blood pressure (Imholz et al., 1988; van Egmond, Hasenbos, and Crul, 1985). It appears that some of this lack of correspondence between methods of blood pressure determination is unique to the vascular structure of individuals. With the device positioned at the recommended heart level, some individuals display estimates of blood pressure that are over 20mm Hg higher than their corresponding oscillometric or auscultatory values, while others display estimates that are over 20mm Hg lower (Larkin et al., 1995).
Calibration of recordings by adjusting arm position above or below heart level improves correspondence between measures, but this effect appears to be only temporary (Larkin et al., 1995).
Regardless of whether the absolute measures of blood pressure obtained from devices employing the vascular unloading principle accurately portray an individual’s resting blood pressure level, the continuous finger arterial recordings provide a reliable index of change in blood pressure in response to acute environmental stimuli (Parati et al.,1989).
Therefore, perhaps the true utility of this instrument is to assist in providing accurate measures of acute blood pressure responses to stress, particularly responses to short-term stressors that may be missed if an intermittent noninvasive measurement is employed. In this usage, Gerin, Pieper, and Pickering (1993), indeed, demonstrated that the FINAPRES™-derived measures of blood pressure were more reliable than blood pressures obtained using an intermittent blood pressure measurement device.
Polefrone, J. M., Manuck, S. B., Larkin, K. T., and Francis, M. E.
Published with assistance from the foundation established in memory of Amasa Stone Mather of the Class of 1907, Yale College.
- Abel, J. A., and Larkin, K. T. (1991). Assessment of cardiovascular reactivity across laboratory and natural settings. Journal of Psychosomatic Research, 35, 365 - 373.
- Achmon, J., Granek, M., Golomb, M., and Hart, J. (1989). Behavioral treatment of essential hypertension: A comparison between cognitive therapy and biofeedback of heart rate. Psychosomatic Medicine, 51, 152 - 164.
- Agras, W. S., Horne, M., and Taylor, C. B. (1982). Expectation and the blood-pressure-lowering effects of relaxation. Psychosomatic Medicine, 44, 389 - 395.
- Agras, W. S., Taylor, C. B., Kraemer, H. C., Southam, M. A., and Schneider, J. A. (1987). Relaxation training for essential hypertension at the worksite: II. The poorly controlled hypertensive. Psychosomatic Medicine, 49, 264 - 273.
- Aivazyan, T. A., Zaitsev, V. P., Khramelashvili, V. V., Golenov, E. V., and Kichkin, V. I. (1988). Psychophysiological interrelations and reactivity characteristics in hypertensives. Health Psychology, 7, 137 - 144.
- al'Absi, M., and Wittmers, L. E. (2003). Enhanced adrenocortical responses to stress in hypertension-prone men and women. Annals of Behavioral Medicine, 25, 52 - 33.
- Albright, C. L., Winkleby, M. A., Ragland, D. R., Fisher, J., and Syme, S. L. (1992). Job strain and prevalence of hypertension in a biracial population of urban bus drivers. American Journal of Public Health, 82, 984 - 989.
- Davidyan, A. (1989). Emotional factors in essential hypertension. Psychosomatic Medicine, 55, 505 - 517.
- Alfredsson, L., Davidyan, A., Fransson, E., de Faire, U., Hallqvist, J., Knutsson, A., et al. (2002). Job strain and major risk factors for coronary heart disease among employed males and females in a Swedish study on work, lipids, and fibrinogen. Scandinavian Journal of Work, Environment and Health, 28, 238 - 248.
Last revised: by Dr. Brain Beutler, M.S., R.D.
Provided by Armina Hypertension Association
Also in this section
- Caffeine-Heavy Energy Drinks Give Jolt to Blood Glucose
- ESC: Entresto for Hypertension? Yes!
- Best and safest blood pressure treatments in kidney and diabetes patients compiled
- Adverse childhood events appear to increase the risk of being a hypertensive adult
- An antihypertensive drug improves corticosteroid-based skin treatments
- Energy drinks raise resting blood pressure
- Large study of hypertension patients highlights key moments at which to intervene
- Hydrogen sulfide could help lower blood pressure
- New Guidelines: Treat Obesity First
- Stroke Rounds: Aspirin Overused for Primary Prevention
- Understanding Dementia
- Alzheimer’s Disease Stages
Post a comment [ + Comment here + ]
There are no comments for this entry yet. [ + Comment here + ]
Comments are moderated by our editors, so there may be a delay between submission and publication of your comment. Offensive or abusive comments will not be published.