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The Incidence of Maternal Artefact During Intrapartum Fetal Heart Rate Monitoring
LETTERS TO THE EDITOR
The Incidence of Maternal Artefact During Intrapartum Fetal Heart Rate Monitoring To the Editor: Paquette et al. make an important contribution to the literature on fetal heart rate monitoring.1 The fetal monitors used in the Paquette study are (to the best of my knowledge), Philips 50 series, the generation of fetal monitors which preceded the Philips Avalon Fetal Monitors. In 2009, an urgent recall of the Avalon fetal monitors FM20, FM 30, FM40, FM50 was issued by Philips.2,3 The letter warned of “a number of complaints of inaccurate ultrasoundderived fetal heart rate readings,” which included “switching between the fetal and maternal heart rates; doubling of the fetal heart rate (FHR); halving of the FHR; mismatch between audible and printed FHR; false decelerations; and noisy or erratic signals.”2 The recall further states that “all of these could result in serious injury or death to the mother or fetus,” that “the frequency of such complaints is greater for these devices than for the previous-generation Philips Series 50 fetal monitors,” but that “Philips does not believe there is a need to stop using Avalon fetal monitors at this time.”2 This coincided with a Type 2 recall from Health Canada and a Class 2 recall from the FDA (based on a decision that the product may cause medically reversible adverse events and/ or that the probability was remote of serious adverse events). Neilson et al. in 2008 reported fetal heart rate tracings in which the maternal and fetal signals are blurred with no clear transition point and listed the adverse outcomes which resulted.4 Neilson et al. stated: This problem is not confined to a single manufacturer or model and can be expected from any of the fetal monitors currently being used in hospital settings. We have discussed this with manufacturers and have notified the Food and Drug Administration of this problem.4 Roger K. Freeman is a co-author of the article by Neilson et al. and an author of the textbook Fetal Heart Rate Monitoring. In the 4th edition of that book, published in 2012, is the following: Since the publication of the third edition of this book, a problem caused by newer instrumentation of FHR monitors has come to our attention [Neilson
et al.5]. . . . With the newer monitors, the transition from fetal to maternal signals does not always transition with discontinuity of recording (signal loss) as with older monitors. There are now more than 20 documented cases of MHR rather than fetal recording from the abdominal Doppler transducer resulting in the birth of three stillborn fetuses and a dozen cases of severe fetal metabolic acidosis resulting in neonatal encephalopathy and later cerebral palsy. . . . This problem has been reported to the FDA, and because of this, some monitors have been recalled.”5 The only major recall of fetal monitors from this time period I have found is the Avalon recall. In retrospect, one wonders if, at least some of the tracings in the article by Neilson et al. are from the recalled Avalon monitors. There are two possible lessons which may be drawn. First, the actual hardware and signal processing algorithms of a given fetal monitor may affect the frequency and morphology of maternal heart rate artefact. Second, the Philips Avalon recall may have been less strong than ideal from a clinical standpoint. In particular the Health Canada/FDA classification as Type 2/Class 2 is questionable, given that most severe adverse birth outcomes are not reversible; and while they may be rare, even with a faulty monitor (due to very low baseline risk), the relative risk may be significant enough to justify urgent replacement. This underscores the need for rigorous critical appraisal of recalls and device alerts by clinicians, perhaps ideally on a national scale by organizations such as the clinical practice committees of the SOGC. Daniel J. Kiely, MDCM, MSc, FRCSC Department of Obstetrics and Gynaecology, Université de Montréal, Montreal QC
REFERENCES 1. Paquette S, Moretti F, O’Reilly K, Ferraro ZM, Oppenheimer L.The incidence of maternal artefact during intrapartum fetal heart rate monitoring. J Obstet Gynaecol Can 2014;36(11):962–8. 2. Philips Healthcare. URGENT—Medical Device Recall. Philips Avalon Fetal Monitors FM20, FM30, FM40, FM50. 2009 November 20. Available at: http://www.healthcare.philips.com/pwc_hc/main/shared/ Assets/Documents/patient_monitoring/avalon/FSN86201075_ AVALON_LETTER_FINAL.pdf.pdf. Accessed December 14, 2014. 3. Philips Avalon Monitors—Addendum—Additional information regarding ultrasound fetal monitoring—English. November 2009. Available at: http://www.healthcare.philips.com/pwc_hc/main/shared/Assets/ Documents/patient_monitoring/avalon/AV_ADD_ENG_ 453564191101.pdf. Accessed December 14, 2014.
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LetterS to the Editor
4. Neilson DR, Freeman RK, Mangan S. Signal ambiguity resulting in unexpected outcome with external fetal heart rate monitoring. Am J Obstet Gynecol 2008;198(6):717–24. 5. Freeman RK, Garite TJ, Nageotte MP, Miller LA. Fetal heart rate monitoring. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012:59–61.
J Obstet Gynaecol Can 2015;37(3):205–206
In Response To the Editor: We would like to thank Dr Kiely for his letter. We agree that he raises an important issue deserving of discussion. We confirm that in our study, the monitors used were mostly Philips Series 50 XM or older and did not have autodetection of maternal heart rate artefact. Artefact detection was performed solely by visual analysis. As Dr Kiely points
206 l MARCH JOGC MARS 2015
out, there are inherent technical issues and problems with the software algorithms’ ability to discriminate between fetal and maternal heart rates, especially in situations where the fetal and maternal heart rates are synchronous. Because of these concerns, one cannot solely rely on automated processes to avoid potential adverse events. This reinforces the need for dual monitoring, using visual cues, and best clinical judgement. Stephanie Paquette, MD Zachary M. Ferraro, PhD Lawrence Oppenheimer, MD Obstetrics, Gynecology and Newborn Care, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology University of Ottawa, The Ottawa Hospital, Ottawa ON
J Obstet Gynaecol Can 2015;37(3):206
The Incidence of Maternal Artefact During Intrapartum Fetal Heart Rate Monitoring To the Editor: Paquette et al. make an important contribution to the literature on fetal heart rate monitoring.1 The fetal monitors used in the Paquette study are (to the best of my knowledge), Philips 50 series, the generation of fetal monitors which preceded the Philips Avalon Fetal Monitors. In 2009, an urgent recall of the Avalon fetal monitors FM20, FM 30, FM40, FM50 was issued by Philips.2,3 The letter warned of “a number of complaints of inaccurate ultrasoundderived fetal heart rate readings,” which included “switching between the fetal and maternal heart rates; doubling of the fetal heart rate (FHR); halving of the FHR; mismatch between audible and printed FHR; false decelerations; and noisy or erratic signals.”2 The recall further states that “all of these could result in serious injury or death to the mother or fetus,” that “the frequency of such complaints is greater for these devices than for the previous-generation Philips Series 50 fetal monitors,” but that “Philips does not believe there is a need to stop using Avalon fetal monitors at this time.”2 This coincided with a Type 2 recall from Health Canada and a Class 2 recall from the FDA (based on a decision that the product may cause medically reversible adverse events and/ or that the probability was remote of serious adverse events). Neilson et al. in 2008 reported fetal heart rate tracings in which the maternal and fetal signals are blurred with no clear transition point and listed the adverse outcomes which resulted.4 Neilson et al. stated: This problem is not confined to a single manufacturer or model and can be expected from any of the fetal monitors currently being used in hospital settings. We have discussed this with manufacturers and have notified the Food and Drug Administration of this problem.4 Roger K. Freeman is a co-author of the article by Neilson et al. and an author of the textbook Fetal Heart Rate Monitoring. In the 4th edition of that book, published in 2012, is the following: Since the publication of the third edition of this book, a problem caused by newer instrumentation of FHR monitors has come to our attention [Neilson
et al.5]. . . . With the newer monitors, the transition from fetal to maternal signals does not always transition with discontinuity of recording (signal loss) as with older monitors. There are now more than 20 documented cases of MHR rather than fetal recording from the abdominal Doppler transducer resulting in the birth of three stillborn fetuses and a dozen cases of severe fetal metabolic acidosis resulting in neonatal encephalopathy and later cerebral palsy. . . . This problem has been reported to the FDA, and because of this, some monitors have been recalled.”5 The only major recall of fetal monitors from this time period I have found is the Avalon recall. In retrospect, one wonders if, at least some of the tracings in the article by Neilson et al. are from the recalled Avalon monitors. There are two possible lessons which may be drawn. First, the actual hardware and signal processing algorithms of a given fetal monitor may affect the frequency and morphology of maternal heart rate artefact. Second, the Philips Avalon recall may have been less strong than ideal from a clinical standpoint. In particular the Health Canada/FDA classification as Type 2/Class 2 is questionable, given that most severe adverse birth outcomes are not reversible; and while they may be rare, even with a faulty monitor (due to very low baseline risk), the relative risk may be significant enough to justify urgent replacement. This underscores the need for rigorous critical appraisal of recalls and device alerts by clinicians, perhaps ideally on a national scale by organizations such as the clinical practice committees of the SOGC. Daniel J. Kiely, MDCM, MSc, FRCSC Department of Obstetrics and Gynaecology, Université de Montréal, Montreal QC
REFERENCES 1. Paquette S, Moretti F, O’Reilly K, Ferraro ZM, Oppenheimer L.The incidence of maternal artefact during intrapartum fetal heart rate monitoring. J Obstet Gynaecol Can 2014;36(11):962–8. 2. Philips Healthcare. URGENT—Medical Device Recall. Philips Avalon Fetal Monitors FM20, FM30, FM40, FM50. 2009 November 20. Available at: http://www.healthcare.philips.com/pwc_hc/main/shared/ Assets/Documents/patient_monitoring/avalon/FSN86201075_ AVALON_LETTER_FINAL.pdf.pdf. Accessed December 14, 2014. 3. Philips Avalon Monitors—Addendum—Additional information regarding ultrasound fetal monitoring—English. November 2009. Available at: http://www.healthcare.philips.com/pwc_hc/main/shared/Assets/ Documents/patient_monitoring/avalon/AV_ADD_ENG_ 453564191101.pdf. Accessed December 14, 2014.
MARCH JOGC MARS 2015 l 205
LetterS to the Editor
4. Neilson DR, Freeman RK, Mangan S. Signal ambiguity resulting in unexpected outcome with external fetal heart rate monitoring. Am J Obstet Gynecol 2008;198(6):717–24. 5. Freeman RK, Garite TJ, Nageotte MP, Miller LA. Fetal heart rate monitoring. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012:59–61.
J Obstet Gynaecol Can 2015;37(3):205–206
In Response To the Editor: We would like to thank Dr Kiely for his letter. We agree that he raises an important issue deserving of discussion. We confirm that in our study, the monitors used were mostly Philips Series 50 XM or older and did not have autodetection of maternal heart rate artefact. Artefact detection was performed solely by visual analysis. As Dr Kiely points
206 l MARCH JOGC MARS 2015
out, there are inherent technical issues and problems with the software algorithms’ ability to discriminate between fetal and maternal heart rates, especially in situations where the fetal and maternal heart rates are synchronous. Because of these concerns, one cannot solely rely on automated processes to avoid potential adverse events. This reinforces the need for dual monitoring, using visual cues, and best clinical judgement. Stephanie Paquette, MD Zachary M. Ferraro, PhD Lawrence Oppenheimer, MD Obstetrics, Gynecology and Newborn Care, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology University of Ottawa, The Ottawa Hospital, Ottawa ON
J Obstet Gynaecol Can 2015;37(3):206