Wireless, remote solution for home fetal and maternal heart rate monitoring

Abstract

BACKGROUND: Access to prenatal care can be challenging due to physician shortages and rural geography. The multiple prenatal visits performed to collect basic fetal measurements lead to significant patient burden as well. The standard of care tools for fetal monitoring, external fetal heart rate monitoring with cardiotocography, as used today, must be applied by a medical professional in a healthcare setting. Novel tools to enable a remote and self-administered fetal monitoring solution would significantly alleviate some of the current barriers to care. OBJECTIVE: To compare maternal and fetal heart rate monitoring data obtained by 'Invu system' (a wireless, wearable, self-administered, fixedlocation device containing passive electrical and acoustic sensors) to cardiotocography, toward a true remote fetal monitoring solution. MATERIALS AND METHODS:A prospective, open-label, multicenter study evaluated concurrent use of Invu and cardiotocography in pregnant women, aged 18 to 50 years, with singleton pregnancies !32þ0 weeks' gestation (NCT03504189). Simultaneous recording sessions from Invu and cardiotocography lasted for !30 minutes. Data from the 8 electrical sensors and 4 acoustic sensors in the Invu belt were acquired, digitized, and sent wirelessly for analysis by an algorithm on cloud-based servers. The algorithm validates the data, preprocesses the data to remove noise, detects heartbeats independently from the two data sources (electrical and acoustic), and fuses the detected heartbeat arrays to calculate fetal heart rate (FHR) and maternal heart rate (MHR). The primary performance endpoint was Invu FHR limit of agreement within AE 10 beats per minute (bpm) of FHR measured with cardiotocography.RESULTS: A total of 147 women were included in the study analysis. The mean (SD) maternal age was 31.8 AE6.9 years, and the mean gestational age was 37.7 AE2.3 weeks. There was a highly significant correlation between FHR measurements from Invu and cardiotocography (r ¼ 0.92; P<0.0001). The 95% limits of agreement for the difference, the range within which most differences between the two measurements will lie, were -8.84 bpm to 8.24 bpm. Invu measurements of MHR were also very similar to cardiotocography and were highly significantly correlated (r ¼ 0.97; P<0.0001). No adverse events were reported during the study. CONCLUSION: Although captured by very different methods, the FHR and MHR outputs wirelessly obtained by the Invu system through passive methods were very similar to those obtained by the current standard of care. The limits of agreement for FHR measured by Invu were within a clinically acceptable AE 8 bpm of cardiotocography FHR. The Invu device uses passive technology to allow for safe, non-invasive and convenient monitoring of patients in the clinic and remotely. Further work should investigate how remote perinatal monitoring could best address some of the recent challenges seen with prenatal care and maternal and fetal outcomes.

A systematic scoping review to identify the design and assess the performance of devices for antenatal continuous fetal monitoring

“…Ten of the 43 studies were from the UK [ 25 – 27 , 35 , 37 – 39 , 49 , 50 , 55 ], 22 from other European countries [ 24 , 28 – 33 , 36 , 40 , 42 – 44 , 48 , 51 – 54 , 56 , 57 , 61 , 64 , 65 ], five from Japan [ 41 , 59 , 60 , 62 , 63 ], one from India [ 45 ], one from Australia [ 66 ], three from the United States of America (USA) [ 46 , 47 , 58 ], and one study from both the Netherlands and USA [ 34 ]. The included studies were heterogeneous, they had a median sample size of 34.5 participants (range 1–657) and a median number of recordings of 63 (range 1–657).…”

“…Three studies investigated both fECG and fPCG devices, all of which were unnamed [ 32 , 37 , 41 ]. The remaining study used a combined fECG/fPCG device named the Invu system [ 46 ].…”

“…All fPCG devices utilised different signal processing methods. ECG data was collected in parallel for three studies [ 32 , 37 , 40 ] for either validation or to aid signal recovery, with one study using a US-based Doppler instrument for reference purposes [ 45 ].The single combined fECG/fPCG device used a combination of electrodes and acoustic sensors, secured to the abdomen using a wireless belt, to monitor the FHR [ 46 ]. The FHR was independently detected by both methods and the signals combined to produce a reliable FHR trace.…”

“…However, fECG devices have been more widely investigated and hence offer a greater opportunity to be optimised and implemented into routine clinical practice than the other technologies. This may be because fECG devices are well established and the included fECG studies date back to 1980 [ 25 ], in comparison to more recent advances made in alternative devices such as fPCG (2008) [ 45 ], fVCG (2008) [ 64 ], accelerometers (2011) [ 66 ] and combined fECG/fPCG devices (2020) [ 46 ]. There has been increasing interest in CFM over the years; Fig 6 shows the studies included in this scoping review only.…”

“…Performance of combined fECG/fPCG devices. Mhajna et al [46] assessed the accuracy of the Invu system at recording the FHR using simultaneous CTG; a highly significant correlation was reported been the two modalities (r = 0.92, p<0.0001).…”