This paper describes the design, fabrication, packaging, and performance characterization of a conformal helix antenna created on the outside of a $\text{10\,mm\,}\times \,\text{30\,mm}$ capsule endoscope designed to operate at a carrier frequency of 433 MHz within human tissue. Wireless data transfer was established between the integrated capsule system and an external receiver. The telemetry system was tested within a tissue phantom and in vivo porcine models. Two different types of transmission modes were tested. The first mode, replicating normal operating conditions, used data packets at a steady power level of 0 dBm, while the capsule was being withdrawn at a steady rate from the small intestine. The second mode, replicating the worst-case clinical scenario of capsule retention within the small bowel, sent data with stepwise increasing power levels of –10, 0, 6, and 10 dBm, with the capsule fixed in position. The temperature of the tissue surrounding the external antenna was monitored at all times using thermistors embedded within the capsule shell to observe potential safety issues. The recorded data showed, for both modes of operation, a low error transmission of 10−3 packet error rate and 10−5 bit error rate and no temperature increase of the tissue according to IEEE standards.
Failure to provide effective analgesia to animals in noxious studies contravenes the obligation to refine animal experimentation and, by increasing ‘noise’ in physiological data sets, may decrease the scientific validity of results. Pig models of surgical conditions are becoming increasingly important and used for translational work. This review aimed to determine the extent to which the recent biomedical literature describes pain assessment and alleviation in pigs recovering from experimental surgery. Three databases (Medline, Web of Knowledge, and Google Scholar) were searched to find relevant studies published from January 2012 to March 2014. Information on pain assessment and peri- and postoperative analgesia was extracted. The review identified 233 papers meeting selection criteria. Most articles (193/233, 83%) described use of drugs with analgesic properties, but only 87/233 (37%) described postoperative analgesia. No article provided justification for the analgesic chosen, despite the lack of guidelines for analgesia in porcine surgical models and the lack of formal studies on this subject. Postoperative pain assessment was reported in only 23/233 (10%) articles. It was found that the reporting of postoperative pain management in the studies was remarkably low, reflecting either under-reporting or under-use. Analgesic description, when given, was frequently too limited to enable reproducibility. Development of a pain-scoring system in pigs, together with the mandatory description of pain management in submitted articles, would contribute to improved laboratory pig welfare.
5 July 2018 in IEEE Transactions on Biomedical Engineering
Clinical endoscopy and colonoscopy are commonly used to investigate and diagnose disorders in the upper gastrointestinal tract and colon respectively. However, examination of the anatomically remote small bowel with conventional endoscopy is challenging. This and advances in miniaturization led to the development of video capsule endoscopy (VCE) to allow small bowel examination in a non-invasive manner. Available since 2001, current capsule endoscopes are limited to viewing the mucosal surface only due to their reliance on optical imaging. To overcome this limitation with submucosal imaging, work is under way to implement microultrasound (μUS) imaging in the same form as VCE devices. This paper describes two prototype capsules, termed Sonocap and Thermocap, which were developed respectively to assess the quality of μUS imaging and the maximum power consumption that can be tolerated for such a system. The capsules were tested in vivo in the oesophagus and small bowel of porcine models. Results are presented in the form of μUS B-scans and safe temperature readings observed up to 100 mW in both biological regions. These results demonstrate that acoustic coupling and μUS imaging can be achieved in vivo in the lumen of the bowel and the maximum power consumption that is possible for miniature μUS systems.