Infants born extremely prematurely present significant clinical and population health challenges. Advances in clinical monitoring can potentially drive improvements in survival and long-term outcomes in this vulnerable population. In this study, a multi-function catheter with ECG, pressure, and temperature sensors is developed and the performance and ideal lead location are tested in a rat model. The ECG signals, transdiaphragmatic pressure, and core body temperature of the rat were recorded from a modified multi-electrode gastric feeding tube with one pressure sensor at the tip and another pressure sensor and temperature sensor at 6 cm from the trip.

The ECG signals were obtained from esophageal electrodes in multiple locations and eventually, optimal electrode locations were identified at 4 and 6 cm from the tip of the feeding tube. Reliable pressure signals at a pressure range of 0-0.2psi (0-14 cm H2O) were obtained from pressure sensors placed above and below the diaphragm. A core temperature of ~41°C was recorded from the temperature sensor which was elevated relative to the rectal temperature measurements due to the experimental setup used.

Our multifunction catheter proved to provide a reliable, strong, high resolution and low noise ECG signal from the esophageal electrodes in an animal model equivalent in size to the preterm infant. In addition, continuous pressure and temperature recordings can simultaneously be extracted, with all 3 sensors contained within a less than 3 mm diameter tube as is routinely used in this population. Integration of these multiple components into a feeding tube, which is already universally used in this population purely for nutrition, will provide significant advances in vital sign monitoring while reducing risk to vulnerable preterm infants.

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