Opfer‐Gehrking, Tonette L.

The objective of the present study was to evaluate the influence of posture on the responses of blood pressure (BP) and heart rate (HR) to the Valsalva manoeuvre (VM). Neurohumoral activation, as well as changes in intravascular and intracardiac volumes and pressures, are well known effects of orthostatic stress. These changes are likely to have significant effects on cardiovascular reflexes, such as the response to the VM. However, the influence of posture on the VM has not been intensively evaluated, except for a few studies involving small sex- and age-selected case series. We therefore investigated the effects of posture on the VM in a larger non-selected group of healthy control subjects. In 19 healthy volunteers (ten female/nine male; age range 20–72 years, mean age 43 years), two reproducible VMs (40 mmHg; 15 s) were performed after 10 min of supine rest, 10 min of sitting and 10 min of standing. HR and BP were monitored continuously. End-diastolic volume, total peripheral resistance and cardiac output were calculated at baseline for each position. We found that assuming an upright position resulted in increases in total peripheral resistance and HR, accompanied by decreases in end-diastolic volume and cardiac output. The fall in BP during early phase II and the BP overshoot during phase IV were clearly more pronounced with increasing orthostatic stress, whereas the rise in BP during late phase II remained unchanged; pulse pressure was more compressed during phase II, but higher during phase IV. The Valsalva ratio was not significantly affected, but baroreflex gain (calculated from early phase II) was significantly decreased in the upright position. While a reduced late phase II was observed on one occasion in each of the lying and sitting positions, three abnormal responses were observed during standing. We conclude that posture has a significant influence on BP responses to the VM, probably resulting from changes in the intrathoracic blood volume. Standing results in a lower rate of ‘flat-top’ responses, but also seems to reduce the specificity of this test. Sympathetic activation in the upright position seems to blunt baroreflexes, leading to similar HR responses in spite of larger changes in BP.

OBJECTIVE—The prevalence of autonomic symptoms and deficits in certain systems is known, but a comprehensive autonomic symptom profile in diabetes is not available. We aimed to estimate this using a laboratory evaluation of autonomic function and a validated self-report measure of autonomic symptoms in patients and matched control subjects from the population-based Rochester Diabetic Neuropathy Study. RESEARCH DESIGN AND METHODS—Participants included 231 patients with diabetes (type 1, n = 83; type 2, n = 148) and 245 healthy age-matched control subjects. We assessed symptoms using a validated self-report instrument (Autonomic Symptom Profile) and evaluated the severity and distribution of autonomic deficits (cardiovagal, sudomotor, adrenergic) with the objective, laboratory-based Composite Autonomic Severity Score (CASS). RESULTS—Autonomic symptoms were present more commonly in type 1 than in type 2 diabetes, with symptoms of orthostatic intolerance, secretomotor, urinary control, diarrhea, and sleep disturbance and pupillomotor, vasomotor, and erectile dysfunction significantly increased over healthy control subjects in type 2 diabetic patients. The prevalence of autonomic impairment was 54% in type 1 and 73% in type 2 diabetic patients. Severity of autonomic failure was mild overall (mean CASS 2.3; maximum 10), with orthostatic hypotension occurring in 8.4 and 7.4% of type 1 and 2 diabetic patients, respectively. Fourteen percent of patients had a CASS ≥5, indicating moderate to severe generalized autonomic failure. The correlation of symptoms with autonomic deficits (CASS) was better in type 1 than type 2 diabetic subjects and was weak overall. CONCLUSIONS—These findings indicate that autonomic symptoms and deficits are common in diabetes, but mild in severity, and that the correlation between symptom scores and deficits is overall weak in mild diabetic neuropathy, emphasizing the need to separately evaluate autonomic symptoms.