The Doppler Study
Research type
Research Study
Full title
Feasibility study to evaluate a new hands-free doppler heart rate monitor normally used to measure the fetal heart rate
IRAS ID
322466
Contact name
Heather Elphick
Contact email
Sponsor organisation
Sheffield Hallam University
Duration of Study in the UK
0 years, 5 months, 22 days
Research summary
During pregnancy, ultrasound doppler is used to determine the heart rate of the fetus (unborn baby). This has been established practice throughout the world for over 40 years. It is accurate and audible, which means that anyone in the room can immediately hear if there is a problem with the fetal heart rate. After birth the heart rate of the new born baby is traditionally detected using a stethoscope over the baby’s chest. This is an inferior technique in that it is only heard by one person, requires a degree of mental arithmetic to calculate the heart rate and is undocumented. In the last few years, studies have shown that the ultrasound doppler used to determine fetal heart rate can also provide an accurate heart rate in the newborn baby. This can be readily recorded for documentation, can be heard by the whole clinical team (and parents), and is much more sensitive than the human ear if the heart beat is slow or weak.
As the previous studies have shown, the fetal doppler works very well on the newborn baby but, as with the stethoscope, it requires one dedicated member of the team caring for the baby to keep the ultrasound probe on the chest. It may be difficult to ensure sufficient but not excessive pressure is being applied to the chest and a varying angle may affect the quality of the signal. Ideally, the sensor needs to be hands-free.
Professor Saatchi’s team have developed a modified fetal doppler probe which provides hands-free monitoring. The probe is linked to the doppler device by a 12-inch length of soft flexible wiring. The small probe sits on the baby’s chest immediately over the heart and is held in place by the normal ultrasound gel used on the mother’s abdomen during labour. The gel ensures a good signal and is thick enough to keep the transducer in position. The chest can be covered with a towel or polythene wrap to keep the baby warm. The heart rate is continuously recorded and wirelessly transferred to a nearby computer. As with a stethoscope the probe is cleaned before use to ensure there is no risk of infection.
We propose an initial small study on 15 children being admitted to the sleep unit at Sheffield Children’s Hospital where Dr Elphick’s clinical team investigates up to 500 children a year. The hands-free doppler will be placed on baby’s chest and the audible signal of the doppler heart sounds will be used to confirm the best positioning of the transducer. The child’s heart rate will be measured over a period of about five minutes with both the hands-free doppler and with the usual method of monitoring on the sleep unit which uses ECG. The rates from the two systems will be compared to evaluate the accuracy of the research method. Information will also be collected from the parent(s) to determine their opinion on the acceptability of the hands-free transducer. This will help us to establish whether the method can be used as a diagnostic tool for use in the future.
REC name
South Central - Oxford C Research Ethics Committee
REC reference
23/SC/0059
Date of REC Opinion
2 Mar 2023
REC opinion
Favourable Opinion