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• Re: Handheld Doppler use for measuring newborn HR has been described in the literature
  Amanda Dyson
  Published on: 21 July 2016
• Handheld Doppler use for measuring newborn HR has been described in the literature
  David J Hutchon
  Published on: 14 June 2016

• Published on: 21 July 2016

  Re: Handheld Doppler use for measuring newborn HR has been described in the literature

  • Amanda Dyson, Dr
  • Other Contributors:
    • Michele Jeffrey and Martin Kluckow

  We thank Dr Hutchon for his interest in our article and acknowledge his contribution to developing this technique of measuring heart rate rapidly and efficiently in newborns. We were particularly interested to hear of his experience with a Doppler that displays an averaged heart rate. We can see that having a displayed rather than counted Doppler heart rate would be highly practical in the delivery room providing that...

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  We thank Dr Hutchon for his interest in our article and acknowledge his contribution to developing this technique of measuring heart rate rapidly and efficiently in newborns. We were particularly interested to hear of his experience with a Doppler that displays an averaged heart rate. We can see that having a displayed rather than counted Doppler heart rate would be highly practical in the delivery room providing that it is accurate, able to detect heart rates of <60bpm and has a suitably short averaging time. During our study we found that counting the audible Doppler sound was considerably more accurate than using the displayed heart rate provided by our Doppler machine Hadeco Smartdop 45(Hadeco--2-7- 11 Arima, Miyamae-ku, Kawasaki, 216-0003, Japan) (1) and cannot find other published data to the contrary. We also agree that there are clearly practical and ergonomic advantages to having a hands free transducer as has been described by Dr Hutchon, particularly if this can be used with a Doppler that is used for fetal heart rate monitoring and therefore already present in the delivery room.

  We think that the focal depth of the probe is likely to have an impact on the accuracy of the device given the variation in size of the neonatal population and found that our 8MHz probe was more accurate in smaller babies <1.5kg (1). We found that while it has been shown that the using a 2MHz probe is effective in detecting the heart rate in newborns over 35 weeks gestation in the delivery room (2), we wonder if the focal depth of 10cm of a 2MHz probe might make it difficult to obtain accurate measurements in smaller preterm newborns and feel that this should be a direction of further research.

  1. Dyson A, Jeffrey M, Kluckow M, Measurement of Newborn Heart Rate Using Handheld Doppler ultrasound, Arch Dis Child Fetal Neonatal Ed doi:10.1136/archdischild-2016-310669

  2. Goenka S, Khan M, Koppel RI, Heiman HS. Precordial Doppler Ultrasound Achieves Earlier and More Accurate Newborn Heart Rates in the Delivery Room. Pediatric Academic Societies and Asian Society for Pediatric Research 2014; 590p.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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• Published on: 14 June 2016

  Handheld Doppler use for measuring newborn HR has been described in the literature

  • David J Hutchon, Retired Obstetrician

  We read this article with considerable interest as it confirms that Precordial Doppler Ultrasound (PDU) can detect the neonatal heart rate within seconds of birth, much earlier than is possible with oximetry and much more reliably than with auscultation. As the authors state "Handheld Doppler use for measuring newborn HR has been described in the literature" (by Goenka et al and by Hutchon) "but needs further investigat...

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  We read this article with considerable interest as it confirms that Precordial Doppler Ultrasound (PDU) can detect the neonatal heart rate within seconds of birth, much earlier than is possible with oximetry and much more reliably than with auscultation. As the authors state "Handheld Doppler use for measuring newborn HR has been described in the literature" (by Goenka et al and by Hutchon) "but needs further investigation before being used clinically.". Dyson et al chose to use a Hadeco Smartdop 45 (Hadeco--2-7-11 Arima, Miyamae-ku, Kawasaki, 216-0003, Japan), which is a bidirectional handheld Doppler usually used for measuring arterial and venous blood flow in the extremities although it can also detect a fetal HR. In 2014 we demonstrated the use of a readily available and low cost dedicated fetal doppler machine and found the 2mHz probe readily detected the neonatal heart rate when placed on the chest(1). We reported on the Contec Sonoline C2 Pocket Fetal Doppler which also provides a digital display of heart rate and records the signal for subsequent computer download, and documentation and review.

  We have also shown that if the transducer is separated from the hand held probe of the machine and connected with light flexible wiring, the lightweight transducer can sit on the neonate's chest held in place simply by the surface tension of the ultrasound gel. This allows hands-free use and avoids the risk of excessive pressure by a handheld probe on the neonate's chest. The position of the transducer on the chest is not critical and can easily be adjusted. By aligning with the skin the transducer automatically scans at 90 degrees.

  https://www.youtube.com/watch?v=ut0vpZxkidI

  Precordial Doppler Ultrasound (PDU) can be readily adapted to provide a measurement of the neonatal heart rate at caesarean section without compromising the sterile surgical field. The Doppler machine is connected to a bluetooth transmitter and placed inside a sterile polythene bag ensuring that transducer is coated in ultrasound gel and in contact with the wall of the bag. The transducer can then be handled by a member of the scrubbed team and applied to the neonatal chest through a further application of ultrasound gel. The signal is received by a matching bluetooth receiver outside the sterile field. This can be used to provide an audible signal to the neonatologist and team and recorded for documentation and audit.

  For the preterm neonate at risk of hypothermia it is important to avoid exposure of the skin and PDU can be carried out through the recommended polythene wrap without the exposure of the neonatal skin required by ECG or oximetry.

  Although we reported on the Contec Sonoline C2 Pocket Fetal Doppler, other machines without a recording facility have been shown to be as effective. After a few minutes when oximetry is functional the PDU becomes redundant.

  References

  Goenka S, Khan M, Koppel RI, Heiman HS. Precordial Doppler Ultrasound Achieves Earlier and More Accurate Newborn Heart Rates in the Delivery Room. Pediatric Academic Societies and Asian Society for Pediatric Research 2014; 590p.

  Hutchon DJR. Technological Developments in Neonatal Care at Birth. J Nurs Care 2014; 3: 218.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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