APPLICABILITY OF NEW TECHNIQUES IN THE ASSESSMENT OF ARTERIAL BAROREFLEX SENSITIVITY IN THE ELDERLY - A COMPARISON WITH ESTABLISHED PHARMACOLOGICAL METHODS

1, There has been considerable interest in techniques recently develop ed for the study of arterial baroreceptor-cardiac reflex sensitivity b ased on analysis of spontaneous baroreflex sequences and on spectral a nalysis, This study examined how these newer techniques agreed with th e established pharmacological methods in elderly subjects, 2, In 20 el derly subjects [10 hypertensive (clinic blood pressure 180 +/- 4/88 +/ - 2 mmHg) and 10 normotensive (clinic blood pressure 136 +/- 3/73 +/- 2 mmHg)], we assessed baroreflex sensitivity from spontaneous sequence s of increasing and decreasing blood pressure and pulse interval and t heir mean, and from spectral analysis to derive alpha, the index of ov erall baroreflex gain, Pharmacological baroreflex sensitivity was deri ved from the blood pressure and pulse interval responses to depressor (sodium nitroprusside) and presser (phenylephrine) stimuli, and their mean, 3, Baroreflex sensitivity was significantly lower in the hyperte nsive group by the pharmacological, sequence and spectral methods (all P <0.05), 4, There was acceptable agreement between pharmacological b aroreflex sensitivity and sequences of the same direction, but with so me systematic bias, There was also reasonable agreement between pharma cological and spectral baroreflex sensitivity and close agreement with out bias between sequence and spectral methods, 5, The newer and estab lished techniques demonstrate acceptable agreement in the elderly, alb eit with some systematic bias, Pharmacological methods have enjoyed hi storical precedence but newer techniques give equivalent results, and are preferable in some circumstances, The newer techniques may be more descriptive of the spontaneous behaviour of the arterial baroreflex a t rest rather than under artificially stimulated conditions.