Haemodynamic changes during a squat test, pulsatile stress and indices of cardiovascular autonomic neuropathy in patients with long-duration type 1 diabetes

Abstract

Aim. -Cardiovascular autonomic neuropathy (CAN) and pulsatile stress are considered to be independent cardiovascular risk factors. This study compared haemodynamic changes during an active orthostatic test in adult patients with type 1 diabetes (T1DM), using low versus high RR E/I ratios as a marker of CAN.Methods. -A total of 20 T1DM patients with low RR E/I ratios were compared with 20 T1DM patients with normal RR E/I ratios, matched for gender (1/1 ratio), age (mean: 46 years) and diabetes duration (22-26 years); 40 matched healthy subjects served as controls. All subjects were evaluated by continuous monitoring of arterial blood pressure (Finapres ® ) and heart rate using a standardized posture test (1-min standing, 1-min squatting, 1-min standing), thus allowing calculation of baroreflex gain.Results. -Compared with controls, T1DM patients showed lower RR E/I ratios, reduced baroreflex gains, higher pulsatile stress (pulse pressure × heart rate), greater squatting-induced pulse pressure rises, orthostatic hypotension and reduced reflex tachycardia. Compared with T1DM patients with preserved RR E/I ratios, T1DM patients with low RR E/I ratios showed reduced post-standing reflex tachycardia and baroreflex gain, and delayed blood pressure recovery, but no markers of increased pulsatile stress. Interestingly, decreased baroreflex gain was significantly associated with both pulsatile stress and microalbuminuria.Conclusion. -The use of RR E/I ratios to separate T1DM patients allows the detection of other CAN markers during an orthostatic posture test, but with no significant differences in pulsatile stress or microalbuminuria. In this context, squatting-derived baroreflex gain appears to be more informative. But. -La neuropathie autonome cardiaque (NAC) et le stress pulsatile sont considérés comme des facteurs de risque cardiovasculaire indépendants. Nous avons comparé les modifications hémodynamiques pendant un test actif d'orthostatisme chez des adultes diabétiques de type 1 (DT1) séparés selon la valeur de RR E/I ratio (basse versus élevée) comme marqueur de NAC. KeywordsMéthodes. -Vingt patients DT1 avec un ratio E/I abaissé ont été comparés à 20 patients DT1 avec un ratio E/I normal, appariés pour le sexe (1/1 ratio), l'âge (moyenne : 46 années) et la durée du diabète (22-26 années). Quarante sujets sains appariés ont servi de témoins. Tous les sujets ont été évalués par une mesure continue de pression artérielle (Finapres Résultats. -Comparés aux témoins, les patients DT1 ont un ratio E/I abaissé, un gain baroréflexe diminué, un stress pulsatile (pression puisée × fréquence cardiaque) accru, une augmentation plus marquée de pression puisée en position accroupie, une hypotension orthostatique et une tachycardie réflexe réduite. Comparés aux patients DT1 avec un ratio E/I préservé, les patients DT1 avec un ratio E/I abaissé ont une diminution de la tachycardie réflexe lors du redressement et une réduction du gain baroréflexe, un retard dans la correction de l'hypotension orthostatique, mais pas d'augm...

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

“…BRG measurements during a squat test have been used extensively by our group to assess CAN in diabetic individuals, mostly patients with T1DM. As summarized in Table 2, it was previously demonstrated that baroreflex gain is significantly reduced in T1DM patients with (a) longer disease duration [16], (b) greater age [26], (c) low R-R E/I ratios [28], (d) microalbuminuria (µA) [37], (e) increased pulsatile stress [26], (f) poor metabolic control [38] and (g) compared with age-matched middle-aged non-diabetic individuals (which was also the case for T2DM patients compared with weight-and age-matched healthy subjects) [27].…”

“…In a recent study [28], haemodynamic changes during a squat test were compared in 20 T1DM patients with low R-R E/I ratios during a deep-breathing test (used as a marker of CAN) and 40 matched healthy subjects. Compared with the controls, the diabetic patients had lower R-R E/I ratios ( …”

“…In a similar, more recent study [28], haemodynamic changes during an active orthostatic test were compared in 20 T1DM patients with low R-R E/I ratios during a deep-breathing test (used as a marker of CAN) and 40 matched healthy subjects. Compared with the controls, the diabetic patients did not exhibit any significantly greater initial BP drop but, instead, showed a delayed BP return to baseline after standing (33 vs 21s; P = 0.0167); this abnormal response may be explained by dampened reflex tachycardia and presumably by reduced sympathetic-driven vasoconstriction.…”

Does gradual change in head positioning affect cerebrovascular physiology?

“…Previous studies have used a variety of techniques to investigate hemodynamic parameters in response to postural change, for example: supine to sitting (Fagard et al 1994), squatting (Philips et al 2012), standing (Ewing et al 1978), or head-up tilt (Youde et al 2003). Uniquely, we used an electronic goniometer to record the degree of head position change on a standard hospital bed, which could enable medically unstable and cognitively impaired patients to comply with the protocol; ideal for AIS patient studies.…”

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

“…Moreover, almost there are no studies in Indians where this position is used by most of the population frequently. [20][21][22][23] Hence, careful analysis of alteration in hemodynamic parameters during the transition from standing to squatting and from squatting to standing helps in the early detection of altered vagal and/or sympathetic function.…”