Initial cardiovascular response on change of posture from squatting to standing

Abstract

The immediate cardiovascular responses on active change from the squatting (control) to the standing position differ from those obtained in the lying-to-standing manoeuvre. Without exception, the first beat after changing from squatting to standing showed a decrease in systolic, diastolic and mean pressure by 2.0 +/- 1.1 kPa (14.6 +/- 8.3 mm Hg), 1.4 +/- 1.7 kPa (10.6 +/- 12.6 mm Hg) and 1.9 +/- 1.0 kPa (13.9 +/- 7.3 mm Hg), respectively. During the 4th or 5th pulse after standing the pulse pressure was significantly higher than when lying (P less than 0.01). Mean pressure reached a minimum of 7.7 +/- 1.9 kPa (57.8 +/- 14.4 mm Hg) after 7.1 +/- 1.1 s. Thereafter the blood pressure increased to a new level within about 15 s. 11 of 16 subjects demonstrated a biphasic heart rate (HR) response. The maximum HR was reached after 11.0 +/- 2.4 s of standing. In all experiments, the peaks in HR were distinctly delayed after the blood pressure dips. We conclude that an arterial baroreflex could be implicated in the immediate HR increase after a squatting-to-standing manoeuvre. The subsequent time course of the initial HR response, however, might be induced by other mechanisms.

Squatting test: A posture to study and counteract cardiovascular abnormalities associated with autonomic dysfunction

“…greatly facilitated the study of haemodynamic changes during dynamic tests (Rossberg & Penaz, 1988;Imholz et al, 1998;Imholz et al, 1990). Various posture tests are classically used to assess haemodynamic orthostatic adaptation and autonomic function.…”

“…Another active manoeuvre, the so-called squatting test, produces the strongest acute orthostatic stress when the subject stands up (Scheen et al, 1990; Marfella et al, 1994a). Careful analysis of BP and HR changes during both transition states, from standing to squatting and from squatting to standing, respectively, provides interesting information as far as performance of baroreflexes and haemodynamic homeostasis are concerned (Rossberg & Penaz, 1988). For instance, the analysis of HR and BP changes occurring during a squatting test has been used by our group to assess orthostatic hypotension (Scheen et al, 1990), cardiovascular autonomic neuropathy (CAN) (Philips et al, 2009) and pulsatile stress (Philips et al, 2008); Philips et al, 2010a; Philips et al, 2010b) in patients with type 1 diabetes mellitus.…”

“…The squat-stand transition induces profound haemodynamic changes (Rossberg & Penaz, 1988, Smith et al, 1994. When normal subjects stand up, systolic BP, diastolic BP, and PP invariably fall.…”

Squatting test: a dynamic postural manoeuvre to study baroreflex sensitivity

“…Non-invasive continuous monitoring of systolic and diastolic BP together with HR, using the servoplethysmomanometry and the volume clamp technique at the finger level (Finapres ® , Finometer ® ), has greatly facilitated the study of haemodynamic changes during postural tests in both clinical research and practice [5,6]. Similar information can be obtained with non-invasive Finapres ® BP recordings as with invasive intra-arterial pressure measurements (considered as the gold standard method) for the assessment of the continuous BP responses to orthostatic stress [5].…”

“…Alternatively, an active manoeuvre, the so-called squatting test, produces even a stronger acute orthostatic stress when the subject stands up [7]. Careful analysis of BP and HR changes during both transition states, from standing to squatting and from squatting to standing, respectively, provides interesting information as far as performance of baroreflexes and haemodynamic homoeostasis [6]. For instance, the analysis of HR and BP changes occurring during a squatting test has been used by our group in patients with diabetes mellitus to assess orthostatic hypotension [7], cardiovascular autonomic neuropathy [7,8] and pulsatile stress [8].…”