Assessment of the Smartpill, a Wireless Sensor, as a Measurement Tool for Intra-Abdominal Pressure (IAP).

Background: The SmartPill, a multisensor ingestible capsule, is marketed for intestinal motility disorders. It includes a pressure sensor, which could be used to study intra-abdominal pressure (IAP) variations. However, the validation data are lacking for this use. Material and Methods: An experimental study was conducted on anesthetized pigs with stepwise variations of IAP (from 0 to 15 mmHg by 3 mmHg steps) generated by laparoscopic insufflation. A SmartPill, inserted by endoscopy, provided intragastric pressure data. These data were compensated to take into account the intrabdominal temperature. They were compared to the pressure recorded by intragastric (IG) and intraperitoneal (IP) wired sensors by statistical Spearman and Bland-Altmann analysis. Results: More than 4500 pressure values for each sensor were generated on two animals. The IG pressure values obtained with the SmartPill were correlated with the IG pressure values obtained with the wired sensor (respectively, Spearman ρ coefficients 0.90 ± 0.08 and 0.72 ± 0.25; bias of -28 ± -0.3 mmHg and -29.2 ± 0.5 mmHg for pigs 1 and 2). The intragastric SmartPill values were also correlated with the IAP measured intra-peritoneally (respectively, Spearman ρ coefficients 0.49 ± 0.18 and 0.57 ± 0.30; bias of -29 ± 1 mmHg and -31 ± 0.7 mmHg for pigs 1 and 2). Conclusions: The SmartPill is a wireless and painless sensor that appears to correctly monitor IAP variations.

A better understanding of daily life abdominal wall mechanical solicitation: Investigation of intra-abdominal pressure variations by intragastric wireless sensor in humans.

Intra-abdominal pressure (IAP), as the main mechanical load applied to the abdominal wall, is decisive in the occurrence of ventral hernia. The objective of the study was to propose a comprehensive evaluation of IAP based on a limited risk and discomfort method. A prospective study was carried out in 20 healthy volunteers. The intragastric pressure, validated for estimating IAP, was assessed by an ingestible pressure sensor. Volunteers realized a set of supervised exercises, then resumed their daily activities with the pressure continuously recorded until gastric emptying. Coughing and jumping exercises resulted in the highest IAP levels with maximum peaks of 65 ± 35 and 67 ± 31 mmHg and pressure rates of 121 and 114 mmHg.s-1 respectively. The position did not affect the IAP variation. Men had significantly higher pressure values for pushing against a wall (P < 0.01), Valsalva maneuver and legs raising (P<0.05) exercises. During daily life, IAP greater than 50, 100, and 150 mmHg occurred on average five times, twice, and once per hour, respectively. This study provides a real-life characterization of the IAP allowing the quantification of mechanical solicitation applied to the abdominal wall and the identification of risk situations for the occurrence of ventral hernias.