Poster V17 - A Novel Abdominal Compression Device and its Effects on Vital Signs in Healthy Individuals

Introduction: Dysautonomia is characterized by an intolerance to changes in body position causing weakness, nausea, and loss of consciousness. In some forms of dysautonomia, such as postural orthostatic tachycardia syndrome (POTS), compression garments are recommended to reduce symptoms. Our group has developed a novel compression device that can provide patient-adjusted pressure to the abdomen. The device is made of an air bladder attached to the interior of a rigid weight belt and is worn with the air bladder contacting the upper abdomen (Figure 1). Inflation of the air bladder applies circumferential pressure to the abdomen up to 40 mmHg.

There are minimal data on the effects of abdominal compression on the vital signs of healthy individuals. Our goal was to determine how abdominal compression impacts blood pressure (BP) and heart rate (HR) in healthy participants. Characterizing this physiologic response will help to contextualize how abdominal compression benefits patients with dysautonomia.

Materials and

Methods: Healthy adult participants were recruited. Exclusion criteria included: having hypertension or other cardiovascular disease, being pregnant, or a history of medical implants.

In each trial, participants laid supine for 3 minutes and were then asked to stand for 3 minutes. BP and HR data were collected once while supine and in 1-minute increments after standing. Additional HR data was collected 15 and 30 seconds after standing. A control trial was done followed by a trial with participants wearing our device inflated to 40 mmHg. BP was measured with an automated blood pressure cuff and HR with a pulse oximeter. Standing BP and HR data were normalized against supine measurements for each trial.

A repeated measures model adjusted for baseline value, time, group and time x group interaction compared the change in normalized BP and HR at each time point between control and abdominal compression trials.

Results, Conclusions, and Discussions: In total, 47 individuals participated. Mean age was 24.0±2.8 years and 63.8% of participants were female. Racial makeup was 55.3% (n=26) Asian, 34% (n=16) White, 8.5% (n=4) Black, and 2.1% (n=1) Hispanic. Average abdominal girth was 79.3±9.4 cm and average BMI was 22.6±3.1 kg/m2. Change in HR was significantly higher (8.7 bpm, 95%CI 5.4 to 12.0, p< 0.001) in the control trial compared to abdominal compression when participants initially stood (t = 0 seconds) (Figure 1). At 15, 30, 60, 120, and 180 seconds after standing, heart rate was decreased when wearing abdominal compression compared to control trials without reaching statistical significance. Across all time points, there was no difference in normalized diastolic BP between control and abdominal compression trials (Figure 2). Change in systolic BP was significantly lower in the control trial at 180 seconds after standing (-3.5 mmHg, 95%CI -6.0 to -0.99, p=0.006) compared to abdominal compression (Figure 3). Across all other time points, systolic BP was not significantly different between treatments.

Our novel abdominal compression device was associated with blunted physiologic heart rate increases immediately after standing. Abdominal compression likely provided increased venous return to the heart leading to transiently improved cardiac output. After an initial increase in preload, venous return returned to baseline resulting in a normalization of heart rate. Abdominal compression had no significant effect on diastolic pressure. This implies that our device does not impact arterial tone as diastolic pressure is a function of arterial resistance. Our device was associated with long-term increases in systolic blood pressure. These changes, however, were not seen in the short-term after standing (0 to 120 seconds).

POTS is a condition within dysautonomia that causes significant increases in heart rate after standing. Individuals with POTS have chronic hypovolemia, venous pooling, and neuroendocrine dysfunction causing decreased preload when changing body position. Our novel abdominal compression device may be a means to increase venous return to help stabilize heart rate in these patients. More research is needed to determine the effects of our novel device on the heart rate, blood pressure, and symptom burden of POTS patients.

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