Short-term postural reflexes in diabetic patients with autonomic dysfunction

Abstract

Aims/hypothesis. Assessment of autonomic dysfunction provides prognostic data in diabetic patients. Clinical tests are limited to heart rate variability and blood pressure measurements. We investigated whether a detailed analysis of postural reflexes of patients during short-term head-up tilting and standing erect (both for 3 min) would provide useful clinical data. Methods. We studied 14 control subjects and 56 patients with Type 2 diabetes, stratified into four matched groups: uncomplicated, micro-albuminuria, marco-albuminuria and autonomic neuropathy, who were tilted 55°three times and were standing erect. Non-invasive finger plethysmography blood pressure measurements, using the Portapres, and impedance cardiac output measurements, using the RheoCardioMonitor, were continuously recorded throughout the study. Wavelets of the response to tilting and standing were drawn. The wavelets for the three tilts were combined to improve definition. The degree of autonomic dysfunction was quantified by calculating the baroreflex sensitivity index from the heart-rate and bloodpressure variability data. Results. Baroreflex sensitivity data confirmed that autonomic dysfunction increased as diabetic complications worsened (p<0.001). Both standing and tilting resulted in an initial decrease in blood pressure followed by recovery, an increase in heart rate which was more pronounced with standing and a decrease in stroke volume. Characteristic and incremental changes in these responses were noted as the complications of diabetes worsened (p<0.001). These were a greater decrease in blood pressure with loss of the recovery phase, a reduced heart-rate response and paradoxically an increase in stroke volume. Conclusion/interpretation. Non-invasive blood-pressure and stroke-volume measurements recorded during short-term tilting and standing promises to be useful in assessing diabetic autonomic dysfunction. [Diabetologia (2004) 47:304-311]

Pulse transit time changes observed with different limb positions

“…Current methods of screening for autonomic dysfunction and impaired reflexes are limited to analysis of HR and BP responses to increased breathing efforts, changes of posture or the cold peripheral test (Jauregui-Renaud et al 2003, Zhang et al 2004). Such tests have the advantage that they can be easily done in clinics without a need for expensive equipment or timeconsuming analyses.…”

“…Such tests have the advantage that they can be easily done in clinics without a need for expensive equipment or timeconsuming analyses. Screening for these abnormalities has now become a routine practice in some pathological assessment clinics (Zhang et al 2004, von Baeyer et al 2005. However, current methods to assess BP changes can cause discomfort to patients and may not be suited for continual monitoring when required (Ng et al 2004).…”

Understanding Critically Ill Patients Hemodynamic Response to Mobilization

“…[26][27][28][29][30][31][32][33] Bed rest lessens carotid-cardiac baroreflex responsiveness, contributing to postural hypotension and tachycardia caused by reductions in stoke volume and cardiac output. 42,43 Another reason for hemodynamic instability in critically ill patients can be inferred from the gravity/spaceflight research. 26 Low vasoconstrictive reserve can occur secondary to the hypovolemia and lead to a lower capacity to buffer orthostatic changes.…”

Hemodynamic Instability: Is It Really a Barrier to Turning Critically Ill Patients?

“…The first area describes the impact of prolonged bed rest and/or space flight research where bed rest was used to simulate weightlessness and the effect that motion has on the cardiovascular system in healthy adults, elderly persons, and patients with diabetes. 1- 25 The second area is research performed on coronary bypass patients and other critically ill patients that examines the impact of a lateral turn and dangling the patient's legs on cardiovascular response and recovery. 21,22,[26][27][28][29][30][31][32] The third body of evidence is the most recent and includes studies of early mobility in critically ill patients that included data on feasibility, safety, and processes of care.…”

“…Autonomic dysfunction increases as diabetic complications worsen. 25 Another reason for hemodynamic instability in critically ill patients can be inferred from the research on gravity and space flight. Cardiovascular instability during a position change is often seen after patients spend prolonged lengths of time in a stationary position.…”