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

Abstract

word count = 225 words SUMMARYThe squatting test is an active posture manoeuvre that imposes one of the most potent orthostatic stresses. In normal subjects, the changes in blood pressure and heart rate are transient because of appropriate baroreflex homeostasis and do not provoke symptoms.However, in various pathological conditions, both the increase in blood pressure during squatting and the decrease in blood pressure during standing may be more important and sustained, potentially leading to complaints and adverse events. Squatting has been used to evaluate patients with tetralogy of Fallot, heart transplant, dysautonomia, including diabetic cardiovascular autonomic neuropathy, and individuals prone to vasovagal syncope. Careful analysis of changes in blood pressure and heart rate during the transition from standing to squatting and from squatting to standing allows the early detection of altered vagal and/or sympathetic function. Of note squatting position has been proposed as a therapeutic mean to counteract the fall in blood pressure in patients suffering from dizziness due to dysautonomia and orthostatic hypotension or presenting pre-syncope symptoms, such as soon after exercise.The aims of the present review are to analyse the haemodynamic pattern during a squatting test in various pathological situations and to describe what may be the negative and positive haemodynamic changes associated with this posture. We were especially interested in using the squatting test for the assessment of cardiovascular autonomic neuropathy associated with diabetes mellitus.

Squatting, a posture test for studying cardiovascular autonomic neuropathy in diabetes

“…In normal, healthy subjects, cardiac output increases over the first 5 s after standing from squatting position due to compression of the leg and abdominal vessels. Rapid (within 15-20 s) BP recovery implies baroreflex stimulation [8], which is associated with tachycardia and secondary peripheral vasoconstriction [12,15]. Propranolol can markedly attenuate reflex tachycardia in normal subjects, suggesting that sympathetic activation plays a key role in this abrupt HR rise [17].…”

“…Indeed, careful analysis of BP and HR changes during the transitions from standing to squatting and, even more interesting, from squatting to standing, provides invaluable information [8]. The squat test can be used to assess autonomic dysfunction especially through calculation ofthe so-called baroreflex gain [12,15]. Our research group [16], as with others [13,17,18], was particularly interested in applying this original potent posture test to assess diabetic CAN.…”

“…The most commonly used tests are the lying-to-standing active manoeuvre in clinical practice, and the head-up 70°-tilt table test passive manoeuvre in clinical research [11]. Another active test, the so-called squat test, produces the strongest orthostatic stress [10,12], more so than the head-up tilt [10,13,14], and can therefore be used to assess autonomic dysfunction [15]. Indeed, careful analysis of BP and HR changes during the transitions from standing to squatting and, even more interesting, from squatting to standing, provides invaluable information [8].…”

Squatting test: a dynamic postural manoeuvre to study baroreflex sensitivity

“…However, alterations in baroreflex function with age may explain the higher risk of postural hypotension in elderly people [2]. Furthermore, several pathological entities may be associated with autonomic disorders and dysregulation of BP homoeostasis leading to orthostatic hypotension and syncope as most obvious adverse events [3,4].…”

“…It aims at summarizing all the pertinent data published in the literature when using this active postural test to assess baroreflex sensitivity. This careful analysis of physiological changes during the transition from standing to squatting and from squatting to standing is a prerequisite before considering corresponding changes in subjects with autonomic dysfunction, such as diabetic patients with cardiovascular autonomic neuropathy [4].…”