Initial Orthostatic Hypotension Induced by Standing up From Squatting

Krediet, C. T. Paul; Wieling, Wouter

doi:10.1002/9780470995013.ch44

Cited by 3 publications

(7 citation statements)

References 6 publications

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“…Another observation that must be taken into consideration when searching for an explanation of IOH is that rising from squatting results in a deeper BP trough compared with standing up from supine ( Figure 5) [6,30,31,[69][70][71]. On average, BP in healthy young adults falls by 60 mmHg SBP (systolic BP) and 40 mmHg DBP (diastolic BP) with a nadir approx.…”

Section: Active Standing From a Squat Evokes More Severe Transient Hymentioning

confidence: 99%

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Initial orthostatic hypotension: review of a forgotten condition

et al. 2007

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Several studies have shown that standing up is a frequent (3-10%) trigger of loss of consciousness both in young and old subjects. An exaggerated transient BP (blood pressure) fall upon standing is the underlying cause. IOH (initial orthostatic hypotension) is defined as a transient BP decrease within 15 s after standing, >40 mmHg SBP (systolic BP) and/or >20 mmHg DBP (diastolic BP) with symptoms of cerebral hypoperfusion. It differs distinctly from typical orthostatic hypotension (i.e. BP decrease >20 mmHg SBP and/or >10 mmHg DBP after 3 min of standing) as the BP decrease is transient. Only continuous beat-to-beat BP measurement during an active standing-up manoeuvre can document this condition. As IOH is only associated with active rising, passive tilting is of no diagnostic value. The pathophysiology of IOH is thought to be a temporal mismatch between cardiac output and vascular resistance. The marked decrease of vascular resistance during rising is similar to that observed at the onset of leg exercise and is absent during head-up tilting. It is attributed to vasodilatation in the working muscle through local mechanisms. Standing up causes an initial increase in venous return through the effects of contraction of leg and abdominal muscles. The consequent sudden increase in right atrial pressure may contribute to the fall in systemic vascular resistance through a reflex effect. This review alerts clinicians and clinician scientists to a common, yet often neglected, condition that occurs only upon an active change of posture and discusses its epidemiology, pathophysiology and management.

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Section: Active Standing From a Squat Evokes More Severe Transient Hymentioning

confidence: 99%

“…On average, BP in healthy young adults falls by 60 mmHg SBP (systolic BP) and 40 mmHg DBP (diastolic BP) with a nadir approx. 7 s after rising [31,71]. Mild symptoms of transient light-headedness are often present [7].…”

Section: Active Standing From a Squat Evokes More Severe Transient Hymentioning

confidence: 99%

Initial orthostatic hypotension: review of a forgotten condition

et al. 2007

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“…Further by Rossberg and Penaz and Krediet and Wieling added that on standing and loss of compression of the legs, there would be an immediate reduction in leg vascular resistance due to already existing locally mediated vasodilatation. [26][27][28][29] Moreover, also supported by studies by Tschakovsky and Sheriff as the muscular effort involved in standing up from a squat position is considerable, it has been demonstrated that rapid vasodilatory mechanisms act in proportion to contraction intensity. [30] This would be expected to cause further vasodilatation.…”

Section: Discussionmentioning

confidence: 81%

“…The leg and buttock muscles are active and there is a restriction of blood flow due to elevated intramuscular pressure compression of the vasculature during squatting. [26,27] This combination of compression of blood vessels, leading to relative ischemia and active muscle contraction, is likely to result in local vasodilatation of the leg and buttock muscle vasculature. Further by Rossberg and Penaz and Krediet and Wieling added that on standing and loss of compression of the legs, there would be an immediate reduction in leg vascular resistance due to already existing locally mediated vasodilatation.…”

Section: Discussionmentioning

confidence: 99%

Squatting maneuver - an easy and efficient method to evaluate postural effect on human arterial blood pressure regulation

Kate¹,

Shanmukhaiah²,

Farheen³

et al. 2017

Natl J Physiol Pharm Pharmacol

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Background: It is always been never ending process to search for the ideal method for cardiovascular autonomic function tests. However, some considerations of the feasible application of the squatting tests seem justified. Squatting is an active posture test that can be used to assess baroreflex sensitivity. Indeed, the shift from squatting to standing imposes a major orthostatic stress leading to rapid and large changes in arterial blood pressure (BP) and heart rate allowing precise baroreflex assessment.[1] Aims and Objectives: The aim of this study is to assess: (1) The frequency of an abnormally large fall in BP on standing from supine and (2) the underlying hemodynamic mechanisms of this fall in BP on standing from supine and from squatting. Materials and Methods: Sample size selected was 100 from first year medical students. Basal hemodynamic parameters were recorded in sitting and squatting position, then alteration in these hemodynamic parameters after standing was noted. The mean of three readings of BP obtained, respectively, in each position was considered representative for that position. Statistical analysis is done. Result: The change in the position from supine to standing causes a fall in the systolic as well as diastolic BP which was not statistically significant, whereas change in position from squatting to standing, the fall in the systolic and diastolic BP were statistically significant. Conclusion: The squatting test is an active posture maneuvers that impose one of the most potent orthostatic stresses. This careful analysis in healthy individuals should help in the understanding of disturbances that may be observed in patients with autonomic dysfunction.

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“…This postural change imposes an effective load on circulatory dynamics. [23][24][25][26][27] The mean value of continuous measurements such as CBF and beat-to-beat SBP in each body posture were taken as representative values and defined as follows:…”

Section: Study Protocol For Measurement Of Hemodynamics During Posturmentioning

confidence: 99%