Comparing the performance of a new disposable pneumatic tocodynamometer with a standard tocodynamometer

The goal was to test a newly developed pneumatic tocodynamometer (pTOCO) that is disposable and lightweight, and evaluate its equivalence to the standard strain gauge-based tocodynamometer (TOCO).

The equivalence between the devices was determined by both mechanical testing and recording of contractile events on women. The data were recorded simultaneously from a pTOCO prototype and standard TOCO that were in place on women who were undergoing routine contraction monitoring in the Labor and Delivery unit at the University of Arkansas for Medical Sciences. In this prospective equivalence study, the output from 31 recordings on 28 pregnant women that had 171 measureable contractions simultaneously in both types of TOCO were analyzed. The traces were scored for contraction start, peak and end times, and the duration of the event was computed from these times.

The response curve to loaded weights and applied pressure were similar for both devices, indicating their mechanical equivalence. The paired differences in times and duration between devices were subjected to mixed-models analysis to test the pTOCO for equivalence with standard TOCOs using the two-one-sided tests procedure. The event times and duration analyzed simultaneously from both TOCO types were all found to be significantly equivalent to within ±10 s (all p-values ≤0.0001).

pTOCO is equivalent to the standard TOCO in the detection of the timing and duration of uterine contractions. pTOCO would provide a lightweight, disposable alternative to commercially available standard TOCOs.