1. 3. University of North Carolina at Chapel Hill, USA
The effect of posture and fasting state on blood pressure responses in individuals with normotension and stage 1 hypertension
Andy Mitchelmore, MSc1, Simon Jobson, PhD1, Danielle Lambrick PhD2, Lee Stoner, PhD3 & James Faulkner, PhD1
Department of Sport & Exercise, University of Winchester, UK; 2. Faculty of Health Sciences, University of Southampton, UK;
3. University of North Carolina at Chapel Hill, USA
Introduction
Oscillometric devices now offer central blood pressure and arterial stiffness readings non-invasively. These measures may be superior to peripheral blood pressure in assessing cardiovascular outcomes (Wang et al., 2009). The SphygmoCor XCEL has been shown to be reliable in a young, healthy population (Young et al., 2015). Accordingly, the purpose of this study was to assess the effect of posture [seated vs. supine] and fasting state [fasted vs. non-fasted] on peripheral and central blood pressures in an older hypertensive or normotensive population. The study is also interested in assessing the reliability of the SphygmoCor XCEL with this population.
Figure 1: SphygmoCor XCEL pulse wave analysis
Results
Posture:
There were no significant differences in seated and supine peripheral BP for normotensive or hypertensive participants (P > .05). Similarly there were no significant differences for central BP (P > .05; Table 1).
Fasting:
There were no differences in fasted and unfasted peripheral BP for normotensive or hypertensive participants (P > .05). Similar findings were observed for cSBP (P > .05; Table1).
The criterion intraclass correlation coefficient value of 0.75 was exceeded for peripheral BP ( ), central BP ( ) and AIx ( ) for all conditions.
Figure 2: SphygmoCor XCEL data output
Method
Eighteen participants (m=6, f=12; age 57±5y) were randomised into supine-first or seated-first conditions. Participants were classified as normotensive (<140/90mmHg) or stage 1 hypertensive (>140/90 mmHg). In the supine-first group, participants adopted a supine position for fifteen minutes. Two measurements were taken (supine + fasted condition). If peripheral systolic blood pressure was >5mmHg different and augmentation index was >4% different, a third measure was recorded. After fifteen minutes seated, these measures were repeated (seated + fasted condition). Participants consumed breakfast and the protocol was repeated in supine + non-fasted and seated + non-fasted conditions. This protocol was repeated on three mornings (7-10am).
The effects of posture and fasted state on central and peripheral BP were assessed using repeated measures analysis of variance. The reproducibility of parameters was assessed using intra-class correlation coefficient.
Table 1 : Means for normotensive and hypertensive groups
Condition
Group
Fasted
Unfasted
Supine
Seated
NormoT PSBP (MmHg)
124 σ9
123 σ12
123 σ10
124 σ11
HyperT PSBP (MmHg)
160 σ20
158 σ20
159 σ18
159 σ21
NormoT CSBP (MmHg)
114 σ9
111 σ10
113 σ9
113 σ10
HyperT CSBP (MmHg)
147 σ18
145 σ18
146 σ16
146 σ20
NormoT Aix (%)
35 σ10
26 σ8
32 σ8
30 σ11
HyperT Aix (%)
32 σ6
27 σ7
31 σ6
29 σ8
Summary and Conclusion
The present study demonstrates that there may be no significant difference between having blood pressure measured fasted or non-fasted, and supine or seated. The table of means suggests some small differences between conditions but none sufficient to meet statistical significance.
The study also demonstrates acceptable reliability of the SphygmoCor XCEL, with peripheral and central blood pressures more reliable than Aix measures.
Although further research is necessary when considering central BP, these findings may be important within a clinical setting.
References
Wang, K.L., Cheng, H.M., Chuang, S.Y., Spurgeon, H.A., Ting, C.T., Lakatta, E.G., Yin, F.C., Chou, P. & Chen, C.H. (2009) ‘Central or peripheral systolic or pulse pressure: which best relates to target organs and future mortality?’, Journal of Hypertension, 27 (3), pp
Young Y.Y., Abdolhosseini, P., Brown, F., Faulkner, J., Lambrick, D., Williams, M.A., Stoner, L. (2015). Reliability of Oscillometric Central Blood Pressure and Arterial Wave Reflection Readings: Effects of Posture and the Fasted State. Journal of Hypertension. 33,