Conference Paper

A Haptic Mouse Design with Stiffening Muscle Layer for Simulating Guarding in Abdominal Palpation Training

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Abstract

A patient would contract surface muscles as a reaction called muscle guarding when experiencing discomfort and pain during physical palpation. This reaction carries important information about an affected location. Training physicians to regulate palpation forces to elicit just enough muscle guarding is a challenge using real patients. Tunable stiffness mechanisms enabled by soft robotics can be effectively integrated into medical simulator designs for effective clinical education. In this paper, we propose a controllable stiffness muscle layer to simulate guarding for abdominal palpation training. Designs with soft, fine and rigid granular jamming, stretchable and non-stretchable layer jamming mechanisms were tested and evaluated as methods to create controllable stiffness muscle. User studies have been carried out on 10 naive participants to differentiate the guarding and non-guarding abdomen with the proposed jamming mechanisms. Muscle samples made of ground coffee (fine granular jamming) and latex layers (stretchable layer jamming) show good usability in simulating abdomen with different stiffness with average success detection rate over 70% for both tested palpation gestures (single finger and multiple fingers) after short pretraining.

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Inspection consists of visual examination of the abdomen with note made of the shape of the abdomen, skin abnormalities, abdominal masses, and the movement of the abdominal wall with respiration. Abnormalities detected on inspection provide clues to intra-abdominal pathology; these are further investigated with auscultation and palpation. Auscultation of the abdomen is performed for detection of altered bowel sounds, rubs, or vascular bruits. Normal peristalsis creates bowel sounds that may be altered or absent by disease. Irritation of serosal surfaces may produce a sound (rub) as an organ moves against the serosal surface. Atherosclerosis may alter arterial blood flow so that a bruit is produced. Palpation is the examination of the abdomen for crepitus of the abdominal wall, for any abdominal tenderness, or for abdominal masses. The liver and kidneys may be palpable in normal individuals, but any other masses are abnormal.
Palpation is a widely used diagnostic method in medical practice. The sensitivity of palpation is highly dependent upon the skill of clinicians, which is often difficult to master. There is a need of simulators in palpation training. This paper summarizes important work and the latest achievements in simulation for palpation training. Three types of simulators; physical models, Virtual Reality (VR) based simulations, and hybrid (computerized and physical) simulators, are surveyed. Comparisons among different kinds of simulators are presented.
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