11/01/2022
By Ruby Kandah

The Francis College of Engineering, Department of Biomedical Engineering and Biotechnology, invites you to attend a doctoral dissertation defense by Ruby Kandah on "Measuring propagation of extremely low-level (0.021 mm) whole-body vibration (WBV) delivered by a crib mattress to infants of differing weights and lying positions and to the trachea of a rabbit."

Candidate Name: Ruby Kandah
Degree: Doctoral
Defense Date: Nov. 14, 2022
Time: Noon to 2 p.m.
Location: Via Zoom
Thesis / Dissertation Title: "Measuring propagation of extremely low-level (0.021 mm) whole-body vibration (WBV) delivered by a crib mattress to infants of differing weights and lying positions and to the trachea of a rabbit"

Advisor:
Bryan Buchholz, Department of Biomedical Engineering, University of Massachusetts, Lowell

Committee Members:

  • David Paydarfar, Department of Neurology, the University of Texas at Austin
  • Craig Armiento, Department of Electrical and Computer Engineering, University of Massachusetts Lowell
  • Peter Grigg, Professor Emeritus, University of Massachusetts Medical School

Abstract:

Whole body vibration (WBV) devices have been extensively studied in adults. Recently, a new WBV device, a vibrating crib mattress, for infants experiencing Apnea of Prematurity (AoP) was introduced by Bloch-Salisbury et al. It was the first device of its kind to target the infant population with a vibration intensity (0.021 mm RMS) more than 50 times lower than any adult WBV device. The crib mattress also delivers a stochastic broadband of frequencies (30-60 Hz), known as Gaussian “noise” to infants. However, very little is known about the vibro-mechanics of propagation for this device; what acceleration does the crib mattress deliver? Do infant weight and lying position affect stochastic vibration transmission? Does vibration propagate to internal organ structures involved in breathing and respiration? To answer these questions, we sought to custom-design an accelerometer measurement unit capable of measuring extremely low-level vibration intensity and use this device in a clinical trial with 10 infants of differing weights and lying positions. We further affixed this device to an endotracheal tube (ETT) and inserted the tube down the trachea of a rabbit model to see if acceleration frequencies are detectable within inner organ structures. We were able to relate 0.021 mm RMS displacement to 0.04 g of acceleration delivered by the mattress stimulation area. We found a linear relationship between the weight of the infant and the acceleration intensity measured at the chest of the infant receiving WBV therapy. We found a small significance of lying position to the transmissibility of acceleration. We detected a resonance effect of acceleration intensity in the trachea of the rabbit. Sub-arousal, extremely low-level, 0.04 g, vibration acceleration delivered by the crib mattress device is the lowest intensity studied clinically in WBV therapy. This vibration travels to the head, chest, abdomen, and trunk body sites of the infant, attenuating at the head and chest while resonating at the abdomen and trunk. Heavier infants during the time of the study reduce the surface acceleration of the mattress and measure a lower acceleration intensity at the chest, signaling a need for a real-time acceleration measurement device. The lying position of the infant on a mattress has little effect on vibration transmission however, certain lying positions are favored clinically. The acceleration delivered by the mattress conclusively travels trans-corporeally, through internal organ structures which resonate with this low-level vibration intensity.