Continuous Measurement Of Heart Rate Research Articles

Single-session Exposure Treatment of Injection Phobia: A Case Study with Continuous Heart Rate Measurement

Abstract A single session tretment of an 18 yr. old girl with an injection phobia of 12 yr. duration is described. The client was successfully treated with exposure in-vivo while her heart rate and subjective anxiety were measured throughout the session. The effects of treatment also generalized to natural situations involving injections, and were sustained at a follow-up 4 years after treatment.

Systolic blood pressure and a simple reaction time task.

ABSTRACTCardiovascular changes during a reaction time task have been hypothetically related to the speed of response with implications for a close connection between the two, but little research has attempted to characterize the pressor response in this situation. In this study, continuous measures of heart rate, respiration, and systolic blood pressure (using a noninvasive tracking‐cuff system) were made in 12 subjects during a visually signalled reaction time task with a fixed foreperiod of 6 sec. Consistent and significant changes were shown over the course of the foreperiod–an increase in systolic pressure, a multiphasic pattern in heart rate, and a decrease in respiration amplitude. There was a nonsignificant increase in respiration rate. Correlations between response latency and various indices of physiological level and change during the foreperiod were low and nonsignificant. The changes in heart rate and systolic blood pressure during the foreperiod appeared independent of one another. Interrelationships between the physiological measures in their phasic and tonic changes, and the implications of the findings for cardiovascular‐behavioral interactions are discussed.

1337 EFFECTS OF CHANGES IN CIRCULATION ON TRANSCUTANEOUS PCO2 (TcPCO2)

We compared TcPCO2 with arterial CO2 (PaCO2) & continuous measures of heart rate (HR) & blood pressure (BP) (T°) in 14 infants (mean GA=32.7 weeks, mean wt.=2011 gms & mean postnatal age=1.76 days). The Novametrix heated electrode was mounted on the chest after calibration (mean calibration time=16.5 min.). The equilibration time (mean=12.15 min.) was directly correlated with GA (r= .74 p <.005). The correlation coefficient for TcPCO2 vs PaCO2 (n=29) was 0.76. The slope of the regression line was 1.15±0.18 with an intercept of 19.18±8.56. HR & BP, indirect measures of tissue perfusion, were related to TcPCO2 using time series & cross correlation analysis. Mean BP, accumulated HR & TcPCO2 were calculated for 3 min. intervals in 4 infants. The relationship between changes in variables was examined following correction for biologic & methodologic lags. The change in TcPCO2 between successive 3 min. intervals was strongly correlated with the changes in HR (Δ TcPCO2 vs Δ HR), range r= -.58 to -.76 & occasionally with the change in BP range r= -.09 to -.46. These results indicate that much of the variability in TcPCO2 can be accounted for by changes in circulation. Variation in tissue perfusion occurring independently of changes in PaCO2 could make estimates of PaCO2 from TcPCO2 highly misleading.

Continuous measurement of heart rate as an indicator of the energy expenditure of sheep.

1. The relationship between the heart rate and the energy expenditure of four sheep, S6, S7, S8 and S1, was studies under conditions known to increase energy metabolism.2. A close relationship between heart rate and energy expenditure was shown to exist in three of the four sheep tested when energy expenditure was increased by cold exposure and by increased levels of food intake.3. The source and magnitude of the errors associated with this relationship were studied by analysis of the variation occurring in the O2 pulse (ml O2/heart beat) of the sheep in response to factors other than those directly related to changes in heart rate. In two sheep, S8 and S6, variations in O2 pulse were random. The errors associated with the estimation, from heart rate measurements, of the energy expenditure of these sheep were ±6.8% and ±8.1% respectively. In the other two sheep, S7 and S1, O2 pulse tended to vary significantly during the experiments, in a way that was not directly related to changes in heart rate. The errors of the relationship in these sheep were ±8.6% and ±13.8% respectively.4. Indirect evidence was obtained to suggest that continuous measurements of heart rate continued to reflect with reasonable accuracy the energy expenditure of the three sheep, S6, S7 and S8 when they were standing and lying and when they were eating.5. Direct measurements were made of the O2 consumption and heart rate of sheep S7 and S1 during the act of eating. The energy expenditure of sheep S7 estimated from its O2 consumption was close to that estimated from measurements of its heart rate. Large errors were noted between these two estimates in sheep S1.6. It was concluded that sheep S8 and S6 would be suitable for long-term experiments designed to predict energy expenditure from heart rate measurements made in the field. Sheep S7 was considered to be of limited value for short-term experiments. Sheep S1 was considered to be unsuitable.