Influence of extra-abdominal and -thoracic pressure on intra-abdominal and -thoracic pressure reported by an intra-cavital pressure measurement method.

Kind of research: basic research in fundamental sciences
Study-design: evaluator-blinded, experimental pilot study
Questions asked: In this study we want to examine if a certain extra-abdominal and extra-thoracal pressure has an influence on the intra-abdominal and intra-thoracal pressure. The extra-abdominal and extra-thoracal pressure wil be registered by sensors and the intra-abdominal and  intra-thoracal pressure will be reported by an intra-cavital pressure measurement method. 

Abstract

van Dun P.L.S.^1; Putseys H.; Van Alsenoy C.; De Backer W.A. ²; Devolder A.²; Willemen M.³; Vandenbril D.³; Serneels S.⁴ ;

 
Introduction This study is part of a research project in which we want to investigate the role of pressure in body cavities and their possible function on physiological processes. In this pilot-study we wanted to examine to what extent a certain extra-abdominal and -thoracic pressure influences the intra-abdominal and -thoracic pressure. We also wanted to look if we could influence intra-abdominal and -thoracic pressure by acting on the respective cavities.

Methods  In this study, 20 volunteers (age 21 -61, mean: 44) received three different weights (1, 3 and 5 kg) on the abdomen and afterwards on the thorax. Our intra-cavitary pressure method, a combination of gastral and esophageal method, was used to measure intra-abdominal and -thoracic pressure. This method consists of a tube with 5 sensors (ECCE Medical, Schoten, Belgium) connected to a double pressure transducer (type RespSponce III, Synetics Medical, Sweden). All signals were lead to a digital converter (DI 220; DATAQ instruments inc.,Akron, Ohio, USA;14 BIT, 500hz) with a resolution of 0,0076 mV or 0,0076 mbar and were saved on a computer (Windaq DI-220, DATAQ instruments INC., Akron, Ohio, USA). The signals were analyzed with browser software (Windaq waveform browser, DATAQ instruments Inc., Akron, Ohio, USA) and then roughly read into Matlab, a software program for statistical analysis.
Furthermore, we investigated how much external manual pressure was needed on the abdomen and subsequently on the thorax to produce a measurable intra-abdominal and –thoracic pressure change. The external pressure was measured by means of a sensor (16 to 3 cm with 100 sensors; RSscan® International, Olen, Belgium) that was placed on the abdomen and afterwards on the sternum. The measurements were then transmitted by means of Bluetooth to our computer.

Results The weights of 1, 3 and 5 kg on the abdomen resulted in a significant increase in pressure of 0,57 mbar; 1,71 mbar and 2,54 mbar respectively in the abdominal cavity (p<0,01).  The weight of 5 kg on the abdomen also resulted in a significant increase of pressure of 2,80 mbar in the thoracic cavity (p<0,01). The weight of 3 kg on the thorax resulted in a significant increase in pressure of 0,17 mbar in the abdominal cavity and 0,89 mbar in the thoracic cavity (p<0,02). The weight of 5 kg on the thorax resulted in a significant increase in pressure of 0,36 mbar in the abdominal cavity and 1,07 mbar in the thoracic cavity (p<0,01). The minimal manual pressure threshold for the abdomen was 8,18 kg and for the thorax 9,05 kg.

Conclusions  In this study we experimented with an intra-cavitary pressure method that was able to measure pressure in two different cavities simultaneously with only one device. Intra-cavitary pressure augmented linearly with the applied extra-cavitary pressure. The results also support previous studies which state that pressure changes in one cavity influences another cavity. Further studies will be needed to confirm these findings and to refine our measuring method. Still much fundamental research is to be done to investigate the influence of manual pressure on body cavities and its possible physiological consequences.