- Email: [email protected]
Response to category II tracings: Does anything help?
Journal Pre-proof
Response to Category II tracings: Does anything help? Nandini Raghuraman MD MS PII: DOI: Reference:
S0146-0005(19)30154-5 https://doi.org/10.1016/j.semperi.2019.151217 YSPER 151217
To appear in:
Seminars in Perinatology
Please cite this article as: Nandini Raghuraman MD MS , Response to Category II tracings: Does anything help?, Seminars in Perinatology (2019), doi: https://doi.org/10.1016/j.semperi.2019.151217
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc.
Response to Category II tracings: Does anything help?
Nandini Raghuraman MD MS
Department of Obstetrics and Gynecology, Washington University School of Medicine in St Louis
Corresponding author: Nandini Raghuraman MD MS Center for Outpatient Health, 10th floor 4901 Forest Park Ave St Louis, MO 63110 Phone: 918 691 7389 Email: [email protected]
Dr. Raghuraman is supported by the Foundation for SMFM/American Association of Obstetricians and Gynecologists Foundation.
Abstract Electronic fetal monitoring (EFM) is the most commonly used tool to screen for intrapartum fetal hypoxia. Category II EFM is present in over 80% of laboring patients and poses a unique challenge to management given the breadth of EFM features that fall within this category. Certain Category II patterns, such as recurrent late or recurrent variable decelerations, are more predictive of neonatal acidemia than others. A key feature among many published algorithms for Category II management is the use of intrauterine fetal resuscitation techniques including maternal oxygen administration, amnioinfusion, intravenous fluid bolus, discontinuation of oxytocin, and tocolytic administration. The goal of intrauterine resuscitation is to prevent or
reverse fetal hypoxia. This is most likely to be successful if the etiology of the Category II EFM pattern is identified and targeted resuscitative measures are performed.
Introduction Electronic fetal monitoring (EFM) is a pervasive component of modern obstetric practice. EFM is used in over 80% of laboring patients making it the most common procedure performed on Labor and Delivery units throughout the United States.1, 2 The goal of intrapartum EFM in this setting is to identify and intervene on fetal hypoxia, thereby preventing the progression to acidemia and associated neonatal morbidity. 3 Nonreassuring fetal status as detected by EFM accounts for nearly a quarter of primary cesarean deliveries.4 This calls for a closer look at the interpretation of EFM and the available interventions for EFM related concerns.
History Prior to the introduction of EFM in the1960s, the standard of care for fetal assessment in labor was intermittent auscultation of fetal heart rate.5 Continuous EFM was first introduced in 1958 by American physician, Dr Edward Hon.6 Hon recognized that instantaneous fetal heart rate assessment via electrocardiography (ECG) was a more sensitive marker of fetal distress than an average rate obtained by intermittent auscultation. Soon thereafter, Callagan and colleagues introduced the concept of using Doppler technology (i.e. sound waves) to capture a continuous fetal heart rate.7 Contemporary EFM methods include Doppler mediated external fetal heart rate
monitors, transvaginal fetal ECG via scalp electrodes, and more recently, transabdominal fetal ECG.8, 9 Decision-support software or computerized interpretation have also been proposed as EFM adjuncts but thus far lack data demonstrating benefit. 10 Upon its introduction decades ago, EFM quickly became engrained in routine obstetric care despite lack of high quality scientific evidence to support its use. The results of studies investigating EFM’s ability to prevent adverse neonatal outcomes are mixed at best. Use of EFM in labor appears to reduce the risk of neonatal seizures.1, 11 However, rates of severe or long term neurodevelopmental outcomes including neonatal encephalopathy and cerebral palsy appear to be unaffected.11=Using a national birth cohort, Chen et al found that intrapartum EFM was associated with lower neonatal and infant mortality compared to no intrapartum EFM. This benefit appeared to be gestational age dependent, with 24-27 week gestations having the greatest benefit or lowest number needed to treat to prevent 1 neonatal death.1 Ananth et al observed a similar temporal decrease in preterm neonatal mortality as the use of EFM increased over time.12 These purported benefits come at the cost of more operative and cesarean deliveries particularly for the indication of nonreassuring fetal status.11, 13
Interpretation The interpretation of EFM, particularly in determining what was reassuring versus nonreassuring, lacked reproducibility when it was first rapidly integrated into obstetric practice. Several studies noted suboptimal inter- and intra-observer variability in the interpretation of fetal heart rate tracings.14-18 In a review of 100 fetal heart rate tracings by five clinicians, Chauhan and colleagues found poor agreement [weighted Kappa 0.15 (<0.20 considered poor agreement)} on
whether the tracing was reassuring or non-reassuring. Furthermore, the clinicians could not accurately use EFM to predict emergent cesarean delivery or neonatal acidemia.14 This degree of inconsistency in EFM interpretation led to the development of the National Institute of Child Health and Human Development (NICHD) EFM guidelines. These guidelines standardized EFM language and introduced a three tiered system of EFM categorization: Category I (predictive of normal fetal acid-base status), Category II (indeterminate in the prediction of abnormal fetal-acid base status), and Category III (predictive of abnormal fetal acid-base status).19 This was followed by subsequent American College of Obstetricians and Gynecologists recommendations for the management of each of these categories.20 Category II is, by far, the most common category observed in laboring patients, with more than 80% of fetuses demonstrating Category II EFM at some point in labor. Category II EFM as a whole has a positive predictive value for neonatal acidemia of 1.1%, primarily because it is a large, heterogeneous group of EFM patterns.15, 21 Within category II, there are features that may be more predictive of neonatal acidemia than others (Table 1). For example, in a cohort of laboring patients ≥37 weeks gestation, Cahill et al found that repetitive late decelerations, repetitive variable decelerations, one or more prolonged decelerations, baseline tachycardia and total deceleration area were associated with acidemia.21, 22
Additionally, increasing time in Category II appears to be associated with neonatal
morbidity.23 The presence of moderate variability, on the other hand, has proven reassuring and is unlikely to be associated with acidemia.19 The breadth of patterns within Category II poses a challenge for uniform and standardized management. Several algorithms have been proposed to standardize management of Category II EFM and perform targeted intervention to prevent fetal metabolic acidemia.24-26 Although the performance of these algorithms in preventing adverse outcomes is mixed, 27 a key element
common to all algorithms for Category II management is the optimization of fetal status via intrauterine resuscitation prior to proceeding with expedited delivery. This warrants a discussion on intrauterine resuscitation techniques and the available evidence for such measures.
Maternal lateral repositioning The goal of maternal repositioning is to maximize placental perfusion by relieving compression of maternal great vessels. Maternal position change may also be helpful in the setting of variable decelerations or prolonged decelerations by relieving umbilical cord compression. Maternal supine position is associated with compression of the inferior vena cava, a decrease in maternal cardiac output and lower fetal oxygen saturation compared to left and right lateral positions.28, 29 The presence of late decelerations in supine laboring patients has been described in the literature,30 although it remains unclear if lateral positioning resolves such decelerations. In the absence of demonstrable harm, however, maternal lateral repositioning appears to be a low risk, potentially helpful resuscitation technique.
Intravenous fluid administration In cases where Category II EFM are attributed to fetal hypoxia from poor placental perfusion, the use of intravenous (IV) fluid boluses theoretically optimizes maternal intravascular volume thereby maximizing placental perfusion and fetal oxygenation. In a randomized trial of 500mL versus 1000mL of IV fluids in laboring patients, the 1000mL bolus was associated with a significant increase in fetal oxygen saturation.31 IV fluids are most commonly administered preceding neuraxial anesthesia placement in an effort t to mitigate abrupt hypotension. There is a
10-12% incidence of hypotension following neuraxial anesthesia placement. However, anesthesia literature suggest no benefit in prevention of hypotension with routine preload of IV fluids.32 Furthermore, excessive IV fluid administration should be limited in patients predisposed to pulmonary edema including those with cardiac conditions or preeclampsia. A recent study by Lappen et al demonstrated a reduced risk of fetal heart rate abnormalities and post epidural hypotension when a 1500mL IV fluid bolus was administered to patients with narrow pulse pressures.33 The ideal choice of IV fluid type remains unknown. Together, these data suggest that routine, prophylactic IV fluid boluses are less likely to be helpful but that a targeted approach of hydrating volume-depleted patients may be beneficial.
Amnioinfusion Variable decelerations represent umbilical cord compression. Amnioinfusion is the process of using an intrauterine pressure catheter to back-fill the uterus with fluid and alleviate umbilical cord compression. Intrapartum amnioinfusion has been shown to reduce the occurrence of recurrent variable decelerations and cesarean delivery for nonreassuring fetal status.34-38 This technique has also been studied for the indications of meconium stained amniotic fluid and chorioamnionitis with results suggesting little to no benefit.35, 39, 40 Although this particular intrauterine resuscitation method has been studied the most, there are still questions about technique that remain unanswered including the type, temperature, and rate of fluid infusion that optimizes neonatal outcomes.
Maternal oxygen administration More than half of laboring patients receive supplemental oxygen for abnormal fetal heart rate tracings even in the absence of maternal hypoxia.41 The theoretic rationale behind this practice is that maternal hyperoxia increases oxygen transfer to the fetus, thereby improving fetal hypoxia and preventing the transition to acidemia. The available evidence for oxygen supplementation in labor suggests no benefit to the neonate and in fact, some randomized clinical trials demonstrate harm with oxygen including higher rates of neonatal acidemia and more infants requiring delivery room resuscitation.42-44 A recent noninferiority randomized controlled trial comparing oxygen to room air for Category II EFM, found no differences in umbilical cord gases, particularly umbilical artery lactate, a marker of fetal metabolic acidosis.45 In the absence of data demonstrating benefit, routine and liberal use of maternal oxygen supplementation in the absence of maternal hypoxia must be carefully considered particularly because excess oxygen exposure is associated with increased free radical activity and subsequent cell damage.46-48
Discontinue oxytocin or administer tocolytic With regular contractions, uterine blood flow becomes cyclic with constriction of the uterine spiral arterioles at the peak of a contraction and resultant temporary cessation of perfusion. During this peak, oxygen transfer to the intervillous space is limited.49 Therefore, it is important to consider uterine hyperactivity as a cause for fetal hypoxia. Tachysystole, defined by the NICHD as average of more than 5 contractions in 10 minutes, is observed in 11% of laboring patients and is associated with cesarean for nonreassuring fetal status and neonatal morbidity including NICU admission and acidemia.50-52 The management of tachysystole includes
administration of a tocolytic and/or discontinuation of oxytocin. In the presence of tachysystole, even without associated fetal heart rate changes, discontinuing or briefly holding oxytocin is a simple intervention that allows for decreased uterine activity and reperfusion. The ideal protocol for subsequent resumption of oxytocin after improvement of tachysystole remains unknown. Terbutaline, a beta agonist, is the most common tocolytic administered for intrapartum uterine relaxation in the face of tachysystole or prolonged contractions with abnormal fetal heart rate tracings. Administration of terbutaline is associated with improvement in intrapartum fetal heart rate abnormalities.53 It is important to note, however, that repeated terbutaline doses should not be given as it is associated with maternal cardiac complications. Uterine relaxation should be considered if the tocometer reveals prolonged contractions or tachysystole, particularly in combination with Category II EFM. However, several questions regarding this technique remain unanswered including the role of other uterine relaxation agents like nitroglycerine, and the effect of sudden reperfusion on neonatal outcomes and oxidative stress.
The cornerstone of Category II EFM management is identifying the cause the observed fetal heart rate patterns. This allows for targeted intervention that is directed at the source of the issue (i.e. cord compression, maternal hypotension, tachysystole) rather than simultaneous utilization of multiple techniques (Figure 1). Although many of these intrapartum techniques remain understudied, considering the etiology of the Category II EFM pattern is likely to lead to a successful resuscitative measure.
References
1.
2. 3.
4. 5. 6. 7. 8. 9.
10. 11.
12.
13.
14.
15.
16. 17. 18.
CHEN HY, CHAUHAN SP, ANANTH CV, VINTZILEOS AM, ABUHAMAD AZ. Electronic fetal heart rate monitoring and its relationship to neonatal and infant mortality in the United States. American journal of obstetrics and gynecology 2011;204:491.e1-10. BAILEY RE. Intrapartum fetal monitoring. American family physician 2009;80:1388-96. ANDRES RL, SAADE G, GILSTRAP LC, et al. Association between umbilical blood gas parameters and neonatal morbidity and death in neonates with pathologic fetal acidemia. American journal of obstetrics and gynecology 1999;181:867-71. BARBER EL, LUNDSBERG LS, BELANGER K, PETTKER CM, FUNAI EF, ILLUZZI JL. Indications contributing to the increasing cesarean delivery rate. Obstet Gynecol 2011;118:29-38. STOUT MJ, CAHILL AG. Electronic fetal monitoring: past, present, and future. Clinics in perinatology 2011;38:127-42, vii. HON EH. The electronic evaluation of the fetal heart rate. Preliminary report. 1958. American journal of obstetrics and gynecology 1996;175:747-8. BERNSTINE RL, CALLAGAN DA. Ultrasonic Doppler inspection of the fetal heart. American journal of obstetrics and gynecology 1966;95:1001-4. COHEN WR, S O, S H, et al. Accuracy and reliability of fetal heart rate monitoring using maternal abdominal surface electrodes. Acta obstetricia et gynecologica Scandinavica 2012;91:1306-13. FRUHMAN G, GAVARD JA, MCCORMICK K, WILSON-GRIFFIN J, AMON E, GROSS GA. Standard External Doppler Fetal Heart Tracings versus External Fetal Electrocardiogram in Very Preterm Gestation: A Pilot Study. AJP reports 2016;6:e378-e83. Computerised interpretation of fetal heart rate during labour (INFANT): a randomised controlled trial. Lancet (London, England) 2017;389:1719-29. ALFIREVIC Z, DEVANE D, GYTE GM. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. The Cochrane database of systematic reviews 2013:Cd006066. ANANTH CV, CHAUHAN SP, CHEN HY, D'ALTON ME, VINTZILEOS AM. Electronic fetal monitoring in the United States: temporal trends and adverse perinatal outcomes. Obstet Gynecol 2013;121:92733. VINTZILEOS AM, NOCHIMSON DJ, GUZMAN ER, KNUPPEL RA, LAKE M, SCHIFRIN BS. Intrapartum electronic fetal heart rate monitoring versus intermittent auscultation: a meta-analysis. Obstet Gynecol 1995;85:149-55. CHAUHAN SP, KLAUSER CK, WOODRING TC, SANDERSON M, MAGANN EF, MORRISON JC. Intrapartum nonreassuring fetal heart rate tracing and prediction of adverse outcomes: interobserver variability. American journal of obstetrics and gynecology 2008;199:623 e1-5. FREY HA, LIU X, LYNCH CD, et al. An evaluation of fetal heart rate characteristics associated with neonatal encephalopathy: a case-control study. BJOG : an international journal of obstetrics and gynaecology 2018;125:1480-87. BEAULIEU MD, FABIA J, LEDUC B, et al. The reproducibility of intrapartum cardiotocogram assessments. Canadian Medical Association journal 1982;127:214-6. DEVANE D, LALOR J. Midwives’ visual interpretation of intrapartum cardiotocographs: intra- and inter-observer agreement. Journal of Advanced Nursing 2005;52:133-41. HELFAND M, MARTON K, UELAND K. Factors involved in the interpretation of fetal monitor tracings. American journal of obstetrics and gynecology 1985;151:737-44.
19.
20. 21. 22.
23. 24.
25. 26. 27.
28. 29.
30. 31. 32. 33. 34. 35. 36.
37.
38.
MACONES GA, HANKINS GD, SPONG CY, HAUTH J, MOORE T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. Obstet Gynecol 2008;112:661-6. ACOG Practice Bulletin No. 106: Intrapartum fetal heart rate monitoring: nomenclature, interpretation, and general management principles. Obstet Gynecol 2009;114:192-202. CAHILL AG, ROEHL KA, ODIBO AO, MACONES GA. Association and prediction of neonatal acidemia. American journal of obstetrics and gynecology 2012;207:206.e1-8. CAHILL AG, TUULI MG, STOUT MJ, LOPEZ JD, MACONES GA. A prospective cohort study of fetal heart rate monitoring: deceleration area is predictive of fetal acidemia. American journal of obstetrics and gynecology 2018;218:523.e1-23.e12. JACKSON M, HOLMGREN CM, ESPLIN MS, HENRY E, VARNER MW. Frequency of fetal heart rate categories and short-term neonatal outcome. Obstet Gynecol 2011;118:803-8. CLARK SL, NAGEOTTE MP, GARITE TJ, et al. Intrapartum management of category II fetal heart rate tracings: towards standardization of care. American journal of obstetrics and gynecology 2013;209:89-97. PARER JT, IKEDA T. A framework for standardized management of intrapartum fetal heart rate patterns. American journal of obstetrics and gynecology 2007;197:26 e1-6. MILLER DA, MILLER LA. Electronic fetal heart rate monitoring: applying principles of patient safety. American journal of obstetrics and gynecology 2012;206:278-83. CLARK SL, HAMILTON EF, GARITE TJ, TIMMINS A, WARRICK PA, SMITH S. The limits of electronic fetal heart rate monitoring in the prevention of neonatal metabolic acidemia. American journal of obstetrics and gynecology 2017;216:163 e1-63 e6. CARBONNE B, BENACHI A, LEVEQUE ML, CABROL D, PAPIERNIK E. Maternal position during labor: effects on fetal oxygen saturation measured by pulse oximetry. Obstet Gynecol 1996;88:797-800. HUMPHRIES A, MIRJALILI SA, TARR GP, THOMPSON JMD, STONE P. The effect of supine positioning on maternal hemodynamics during late pregnancy. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstet 2018:1-8. ABITBOL MM. Supine position in labor and associated fetal heart rate changes. Obstet Gynecol 1985;65:481-6. SIMPSON KR, JAMES DC. Efficacy of intrauterine resuscitation techniques in improving fetal oxygen status during labor. Obstet Gynecol 2005;105:1362-8. KINSELLA SM, PIRLET M, MILLS MS, TUCKEY JP, THOMAS TA. Randomized study of intravenous fluid preload before epidural analgesia during labour. Br J Anaesth 2000;85:311-3. LAPPEN JR, MYERS SA, BOLDEN N, MERCER BM, CHIEN EKS. Maternal Pulse Pressure and the Risk of Postepidural Complications: A Randomized Controlled Trial. Obstet Gynecol 2017;130:1366-76. MIYAZAKI FS, NEVAREZ F. Saline amnioinfusion for relief of repetitive variable decelerations: a prospective randomized study. American journal of obstetrics and gynecology 1985;153:301-6. HOFMEYR GJ, LAWRIE TA. Amnioinfusion for potential or suspected umbilical cord compression in labour. The Cochrane database of systematic reviews 2012;1:Cd000013. PITT C, SANCHEZ-RAMOS L, KAUNITZ AM, GAUDIER F. Prophylactic amnioinfusion for intrapartum oligohydramnios: a meta-analysis of randomized controlled trials. Obstet Gynecol 2000;96:8616. STRONG TH, JR., HETZLER G, SARNO AP, PAUL RH. Prophylactic intrapartum amnioinfusion: a randomized clinical trial. American journal of obstetrics and gynecology 1990;162:1370-4; discussion 74-5. OWEN J, HENSON BV, HAUTH JC. A prospective randomized study of saline solution amnioinfusion. American journal of obstetrics and gynecology 1990;162:1146-9.
39.
40. 41. 42.
43.
44.
45.
46.
47.
48. 49. 50.
51. 52.
53.
XU H, HOFMEYR J, ROY C, FRASER W. Intrapartum amnioinfusion for meconium-stained amniotic fluid: a systematic review of randomised controlled trials. BJOG : an international journal of obstetrics and gynaecology 2007;114:383-90. SPONG CY, OGUNDIPE OA, ROSS MG. Prophylactic amnioinfusion for meconium-stained amniotic fluid. American journal of obstetrics and gynecology 1994;171:931-5. HAMEL MS, ANDERSON BL, ROUSE DJ. Oxygen for intrauterine resuscitation: of unproved benefit and potentially harmful. American journal of obstetrics and gynecology 2014;211:124-7. THORP JA, TROBOUGH T, EVANS R, HEDRICK J, YEAST JD. The effect of maternal oxygen administration during the second stage of labor on umbilical cord blood gas values: a randomized controlled prospective trial. American journal of obstetrics and gynecology 1995;172:465-74. NESTERENKO TH, ACUN C, MOHAMED MA, et al. Is it a safe practice to administer oxygen during uncomplicated delivery: a randomized controlled trial? Early human development 2012;88:67781. QIAN G, XU X, CHEN L, et al. The effect of maternal low flow oxygen administration during the second stage of labour on umbilical cord artery pH: a randomised controlled trial. BJOG : an international journal of obstetrics and gynaecology 2017;124:678-85. RAGHURAMAN N WL, TEMMING LA, WOOLFOLK C, MACONES GA, TUULI MG, CAHILL AG. Effect of Oxygen vs Room Air on Intrauterine Fetal Resuscitation: A Randomized Noninferioirty Clinical Trial JAMA Pediatrics 2018;In Press, Accepted April 2018. KHAW KS, WANG CC, NGAN KEE WD, PANG CP, ROGERS MS. Effects of high inspired oxygen fraction during elective caesarean section under spinal anaesthesia on maternal and fetal oxygenation and lipid peroxidation. Br J Anaesth 2002;88:18-23. HELMERHORST HJ, SCHULTZ MJ, VAN DER VOORT PH, DE JONGE E, VAN WESTERLOO DJ. Bench-to-bedside review: the effects of hyperoxia during critical illness. Critical care (London, England) 2015;19:284. DAMIANI E, DONATI A, GIRARDIS M. Oxygen in the critically ill: friend or foe? Current opinion in anaesthesiology 2018;31:129-35. GARITE TJ, SIMPSON KR. Intrauterine resuscitation during labor. Clinical obstetrics and gynecology 2011;54:28-39. HEUSER CC, KNIGHT S, ESPLIN MS, et al. Tachysystole in term labor: incidence, risk factors, outcomes, and effect on fetal heart tracings. American journal of obstetrics and gynecology 2013;209:32.e1-6. BAKKER PC, KURVER PH, KUIK DJ, VAN GEIJN HP. Elevated uterine activity increases the risk of fetal acidosis at birth. American journal of obstetrics and gynecology 2007;196:313 e1-6. AHMED AI, ZHU L, ALDHAHERI S, SAKR S, MINKOFF H, HABERMAN S. Uterine tachysystole in spontaneous labor at term. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstet 2016;29:3335-9. KULIER R, HOFMEYR GJ. Tocolytics for suspected intrapartum fetal distress. The Cochrane database of systematic reviews 2000:CD000035.
Table 1: Category II EFM features associated with metabolic acidemia
Category II Feature
Adjusted Odds Ratio (95% Confidence Interval)
Prolonged decelerations
3.02 (1.64-5.55)
Tachycardia
2.99 (1.55-5.77)
Recurrent late decelerations
2.46 (1.10-4.29)
Recurrent variable decelerations
1.91 (1.07-3.08)
Total deceleration area >95th percentile
3.79 (2.04-7.04)
Adapted from Cahill, A.G., et al., Association and prediction of neonatal acidemia. Am J Obstet Gynecol, 2012. 207(3): p. 206.e1-8.
Figure 1: Targeted Intrauterine Resuscitation
What is etiology of Category II tracing? Maternal position
Lateral positioning
Uterine activity
Hold oxytocin
Administer terbutaline
Maternal hypovolemia
IV fluid bolus
Umbilical cord compression
Reposition
Amnioinfusion
Maternal hypoxia
Maternal O2 administration
Response to Category II tracings: Does anything help? Nandini Raghuraman MD MS PII: DOI: Reference:
S0146-0005(19)30154-5 https://doi.org/10.1016/j.semperi.2019.151217 YSPER 151217
To appear in:
Seminars in Perinatology
Please cite this article as: Nandini Raghuraman MD MS , Response to Category II tracings: Does anything help?, Seminars in Perinatology (2019), doi: https://doi.org/10.1016/j.semperi.2019.151217
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc.
Response to Category II tracings: Does anything help?
Nandini Raghuraman MD MS
Department of Obstetrics and Gynecology, Washington University School of Medicine in St Louis
Corresponding author: Nandini Raghuraman MD MS Center for Outpatient Health, 10th floor 4901 Forest Park Ave St Louis, MO 63110 Phone: 918 691 7389 Email: [email protected]
Dr. Raghuraman is supported by the Foundation for SMFM/American Association of Obstetricians and Gynecologists Foundation.
Abstract Electronic fetal monitoring (EFM) is the most commonly used tool to screen for intrapartum fetal hypoxia. Category II EFM is present in over 80% of laboring patients and poses a unique challenge to management given the breadth of EFM features that fall within this category. Certain Category II patterns, such as recurrent late or recurrent variable decelerations, are more predictive of neonatal acidemia than others. A key feature among many published algorithms for Category II management is the use of intrauterine fetal resuscitation techniques including maternal oxygen administration, amnioinfusion, intravenous fluid bolus, discontinuation of oxytocin, and tocolytic administration. The goal of intrauterine resuscitation is to prevent or
reverse fetal hypoxia. This is most likely to be successful if the etiology of the Category II EFM pattern is identified and targeted resuscitative measures are performed.
Introduction Electronic fetal monitoring (EFM) is a pervasive component of modern obstetric practice. EFM is used in over 80% of laboring patients making it the most common procedure performed on Labor and Delivery units throughout the United States.1, 2 The goal of intrapartum EFM in this setting is to identify and intervene on fetal hypoxia, thereby preventing the progression to acidemia and associated neonatal morbidity. 3 Nonreassuring fetal status as detected by EFM accounts for nearly a quarter of primary cesarean deliveries.4 This calls for a closer look at the interpretation of EFM and the available interventions for EFM related concerns.
History Prior to the introduction of EFM in the1960s, the standard of care for fetal assessment in labor was intermittent auscultation of fetal heart rate.5 Continuous EFM was first introduced in 1958 by American physician, Dr Edward Hon.6 Hon recognized that instantaneous fetal heart rate assessment via electrocardiography (ECG) was a more sensitive marker of fetal distress than an average rate obtained by intermittent auscultation. Soon thereafter, Callagan and colleagues introduced the concept of using Doppler technology (i.e. sound waves) to capture a continuous fetal heart rate.7 Contemporary EFM methods include Doppler mediated external fetal heart rate
monitors, transvaginal fetal ECG via scalp electrodes, and more recently, transabdominal fetal ECG.8, 9 Decision-support software or computerized interpretation have also been proposed as EFM adjuncts but thus far lack data demonstrating benefit. 10 Upon its introduction decades ago, EFM quickly became engrained in routine obstetric care despite lack of high quality scientific evidence to support its use. The results of studies investigating EFM’s ability to prevent adverse neonatal outcomes are mixed at best. Use of EFM in labor appears to reduce the risk of neonatal seizures.1, 11 However, rates of severe or long term neurodevelopmental outcomes including neonatal encephalopathy and cerebral palsy appear to be unaffected.11=Using a national birth cohort, Chen et al found that intrapartum EFM was associated with lower neonatal and infant mortality compared to no intrapartum EFM. This benefit appeared to be gestational age dependent, with 24-27 week gestations having the greatest benefit or lowest number needed to treat to prevent 1 neonatal death.1 Ananth et al observed a similar temporal decrease in preterm neonatal mortality as the use of EFM increased over time.12 These purported benefits come at the cost of more operative and cesarean deliveries particularly for the indication of nonreassuring fetal status.11, 13
Interpretation The interpretation of EFM, particularly in determining what was reassuring versus nonreassuring, lacked reproducibility when it was first rapidly integrated into obstetric practice. Several studies noted suboptimal inter- and intra-observer variability in the interpretation of fetal heart rate tracings.14-18 In a review of 100 fetal heart rate tracings by five clinicians, Chauhan and colleagues found poor agreement [weighted Kappa 0.15 (<0.20 considered poor agreement)} on
whether the tracing was reassuring or non-reassuring. Furthermore, the clinicians could not accurately use EFM to predict emergent cesarean delivery or neonatal acidemia.14 This degree of inconsistency in EFM interpretation led to the development of the National Institute of Child Health and Human Development (NICHD) EFM guidelines. These guidelines standardized EFM language and introduced a three tiered system of EFM categorization: Category I (predictive of normal fetal acid-base status), Category II (indeterminate in the prediction of abnormal fetal-acid base status), and Category III (predictive of abnormal fetal acid-base status).19 This was followed by subsequent American College of Obstetricians and Gynecologists recommendations for the management of each of these categories.20 Category II is, by far, the most common category observed in laboring patients, with more than 80% of fetuses demonstrating Category II EFM at some point in labor. Category II EFM as a whole has a positive predictive value for neonatal acidemia of 1.1%, primarily because it is a large, heterogeneous group of EFM patterns.15, 21 Within category II, there are features that may be more predictive of neonatal acidemia than others (Table 1). For example, in a cohort of laboring patients ≥37 weeks gestation, Cahill et al found that repetitive late decelerations, repetitive variable decelerations, one or more prolonged decelerations, baseline tachycardia and total deceleration area were associated with acidemia.21, 22
Additionally, increasing time in Category II appears to be associated with neonatal
morbidity.23 The presence of moderate variability, on the other hand, has proven reassuring and is unlikely to be associated with acidemia.19 The breadth of patterns within Category II poses a challenge for uniform and standardized management. Several algorithms have been proposed to standardize management of Category II EFM and perform targeted intervention to prevent fetal metabolic acidemia.24-26 Although the performance of these algorithms in preventing adverse outcomes is mixed, 27 a key element
common to all algorithms for Category II management is the optimization of fetal status via intrauterine resuscitation prior to proceeding with expedited delivery. This warrants a discussion on intrauterine resuscitation techniques and the available evidence for such measures.
Maternal lateral repositioning The goal of maternal repositioning is to maximize placental perfusion by relieving compression of maternal great vessels. Maternal position change may also be helpful in the setting of variable decelerations or prolonged decelerations by relieving umbilical cord compression. Maternal supine position is associated with compression of the inferior vena cava, a decrease in maternal cardiac output and lower fetal oxygen saturation compared to left and right lateral positions.28, 29 The presence of late decelerations in supine laboring patients has been described in the literature,30 although it remains unclear if lateral positioning resolves such decelerations. In the absence of demonstrable harm, however, maternal lateral repositioning appears to be a low risk, potentially helpful resuscitation technique.
Intravenous fluid administration In cases where Category II EFM are attributed to fetal hypoxia from poor placental perfusion, the use of intravenous (IV) fluid boluses theoretically optimizes maternal intravascular volume thereby maximizing placental perfusion and fetal oxygenation. In a randomized trial of 500mL versus 1000mL of IV fluids in laboring patients, the 1000mL bolus was associated with a significant increase in fetal oxygen saturation.31 IV fluids are most commonly administered preceding neuraxial anesthesia placement in an effort t to mitigate abrupt hypotension. There is a
10-12% incidence of hypotension following neuraxial anesthesia placement. However, anesthesia literature suggest no benefit in prevention of hypotension with routine preload of IV fluids.32 Furthermore, excessive IV fluid administration should be limited in patients predisposed to pulmonary edema including those with cardiac conditions or preeclampsia. A recent study by Lappen et al demonstrated a reduced risk of fetal heart rate abnormalities and post epidural hypotension when a 1500mL IV fluid bolus was administered to patients with narrow pulse pressures.33 The ideal choice of IV fluid type remains unknown. Together, these data suggest that routine, prophylactic IV fluid boluses are less likely to be helpful but that a targeted approach of hydrating volume-depleted patients may be beneficial.
Amnioinfusion Variable decelerations represent umbilical cord compression. Amnioinfusion is the process of using an intrauterine pressure catheter to back-fill the uterus with fluid and alleviate umbilical cord compression. Intrapartum amnioinfusion has been shown to reduce the occurrence of recurrent variable decelerations and cesarean delivery for nonreassuring fetal status.34-38 This technique has also been studied for the indications of meconium stained amniotic fluid and chorioamnionitis with results suggesting little to no benefit.35, 39, 40 Although this particular intrauterine resuscitation method has been studied the most, there are still questions about technique that remain unanswered including the type, temperature, and rate of fluid infusion that optimizes neonatal outcomes.
Maternal oxygen administration More than half of laboring patients receive supplemental oxygen for abnormal fetal heart rate tracings even in the absence of maternal hypoxia.41 The theoretic rationale behind this practice is that maternal hyperoxia increases oxygen transfer to the fetus, thereby improving fetal hypoxia and preventing the transition to acidemia. The available evidence for oxygen supplementation in labor suggests no benefit to the neonate and in fact, some randomized clinical trials demonstrate harm with oxygen including higher rates of neonatal acidemia and more infants requiring delivery room resuscitation.42-44 A recent noninferiority randomized controlled trial comparing oxygen to room air for Category II EFM, found no differences in umbilical cord gases, particularly umbilical artery lactate, a marker of fetal metabolic acidosis.45 In the absence of data demonstrating benefit, routine and liberal use of maternal oxygen supplementation in the absence of maternal hypoxia must be carefully considered particularly because excess oxygen exposure is associated with increased free radical activity and subsequent cell damage.46-48
Discontinue oxytocin or administer tocolytic With regular contractions, uterine blood flow becomes cyclic with constriction of the uterine spiral arterioles at the peak of a contraction and resultant temporary cessation of perfusion. During this peak, oxygen transfer to the intervillous space is limited.49 Therefore, it is important to consider uterine hyperactivity as a cause for fetal hypoxia. Tachysystole, defined by the NICHD as average of more than 5 contractions in 10 minutes, is observed in 11% of laboring patients and is associated with cesarean for nonreassuring fetal status and neonatal morbidity including NICU admission and acidemia.50-52 The management of tachysystole includes
administration of a tocolytic and/or discontinuation of oxytocin. In the presence of tachysystole, even without associated fetal heart rate changes, discontinuing or briefly holding oxytocin is a simple intervention that allows for decreased uterine activity and reperfusion. The ideal protocol for subsequent resumption of oxytocin after improvement of tachysystole remains unknown. Terbutaline, a beta agonist, is the most common tocolytic administered for intrapartum uterine relaxation in the face of tachysystole or prolonged contractions with abnormal fetal heart rate tracings. Administration of terbutaline is associated with improvement in intrapartum fetal heart rate abnormalities.53 It is important to note, however, that repeated terbutaline doses should not be given as it is associated with maternal cardiac complications. Uterine relaxation should be considered if the tocometer reveals prolonged contractions or tachysystole, particularly in combination with Category II EFM. However, several questions regarding this technique remain unanswered including the role of other uterine relaxation agents like nitroglycerine, and the effect of sudden reperfusion on neonatal outcomes and oxidative stress.
The cornerstone of Category II EFM management is identifying the cause the observed fetal heart rate patterns. This allows for targeted intervention that is directed at the source of the issue (i.e. cord compression, maternal hypotension, tachysystole) rather than simultaneous utilization of multiple techniques (Figure 1). Although many of these intrapartum techniques remain understudied, considering the etiology of the Category II EFM pattern is likely to lead to a successful resuscitative measure.
References
1.
2. 3.
4. 5. 6. 7. 8. 9.
10. 11.
12.
13.
14.
15.
16. 17. 18.
CHEN HY, CHAUHAN SP, ANANTH CV, VINTZILEOS AM, ABUHAMAD AZ. Electronic fetal heart rate monitoring and its relationship to neonatal and infant mortality in the United States. American journal of obstetrics and gynecology 2011;204:491.e1-10. BAILEY RE. Intrapartum fetal monitoring. American family physician 2009;80:1388-96. ANDRES RL, SAADE G, GILSTRAP LC, et al. Association between umbilical blood gas parameters and neonatal morbidity and death in neonates with pathologic fetal acidemia. American journal of obstetrics and gynecology 1999;181:867-71. BARBER EL, LUNDSBERG LS, BELANGER K, PETTKER CM, FUNAI EF, ILLUZZI JL. Indications contributing to the increasing cesarean delivery rate. Obstet Gynecol 2011;118:29-38. STOUT MJ, CAHILL AG. Electronic fetal monitoring: past, present, and future. Clinics in perinatology 2011;38:127-42, vii. HON EH. The electronic evaluation of the fetal heart rate. Preliminary report. 1958. American journal of obstetrics and gynecology 1996;175:747-8. BERNSTINE RL, CALLAGAN DA. Ultrasonic Doppler inspection of the fetal heart. American journal of obstetrics and gynecology 1966;95:1001-4. COHEN WR, S O, S H, et al. Accuracy and reliability of fetal heart rate monitoring using maternal abdominal surface electrodes. Acta obstetricia et gynecologica Scandinavica 2012;91:1306-13. FRUHMAN G, GAVARD JA, MCCORMICK K, WILSON-GRIFFIN J, AMON E, GROSS GA. Standard External Doppler Fetal Heart Tracings versus External Fetal Electrocardiogram in Very Preterm Gestation: A Pilot Study. AJP reports 2016;6:e378-e83. Computerised interpretation of fetal heart rate during labour (INFANT): a randomised controlled trial. Lancet (London, England) 2017;389:1719-29. ALFIREVIC Z, DEVANE D, GYTE GM. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. The Cochrane database of systematic reviews 2013:Cd006066. ANANTH CV, CHAUHAN SP, CHEN HY, D'ALTON ME, VINTZILEOS AM. Electronic fetal monitoring in the United States: temporal trends and adverse perinatal outcomes. Obstet Gynecol 2013;121:92733. VINTZILEOS AM, NOCHIMSON DJ, GUZMAN ER, KNUPPEL RA, LAKE M, SCHIFRIN BS. Intrapartum electronic fetal heart rate monitoring versus intermittent auscultation: a meta-analysis. Obstet Gynecol 1995;85:149-55. CHAUHAN SP, KLAUSER CK, WOODRING TC, SANDERSON M, MAGANN EF, MORRISON JC. Intrapartum nonreassuring fetal heart rate tracing and prediction of adverse outcomes: interobserver variability. American journal of obstetrics and gynecology 2008;199:623 e1-5. FREY HA, LIU X, LYNCH CD, et al. An evaluation of fetal heart rate characteristics associated with neonatal encephalopathy: a case-control study. BJOG : an international journal of obstetrics and gynaecology 2018;125:1480-87. BEAULIEU MD, FABIA J, LEDUC B, et al. The reproducibility of intrapartum cardiotocogram assessments. Canadian Medical Association journal 1982;127:214-6. DEVANE D, LALOR J. Midwives’ visual interpretation of intrapartum cardiotocographs: intra- and inter-observer agreement. Journal of Advanced Nursing 2005;52:133-41. HELFAND M, MARTON K, UELAND K. Factors involved in the interpretation of fetal monitor tracings. American journal of obstetrics and gynecology 1985;151:737-44.
19.
20. 21. 22.
23. 24.
25. 26. 27.
28. 29.
30. 31. 32. 33. 34. 35. 36.
37.
38.
MACONES GA, HANKINS GD, SPONG CY, HAUTH J, MOORE T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. Obstet Gynecol 2008;112:661-6. ACOG Practice Bulletin No. 106: Intrapartum fetal heart rate monitoring: nomenclature, interpretation, and general management principles. Obstet Gynecol 2009;114:192-202. CAHILL AG, ROEHL KA, ODIBO AO, MACONES GA. Association and prediction of neonatal acidemia. American journal of obstetrics and gynecology 2012;207:206.e1-8. CAHILL AG, TUULI MG, STOUT MJ, LOPEZ JD, MACONES GA. A prospective cohort study of fetal heart rate monitoring: deceleration area is predictive of fetal acidemia. American journal of obstetrics and gynecology 2018;218:523.e1-23.e12. JACKSON M, HOLMGREN CM, ESPLIN MS, HENRY E, VARNER MW. Frequency of fetal heart rate categories and short-term neonatal outcome. Obstet Gynecol 2011;118:803-8. CLARK SL, NAGEOTTE MP, GARITE TJ, et al. Intrapartum management of category II fetal heart rate tracings: towards standardization of care. American journal of obstetrics and gynecology 2013;209:89-97. PARER JT, IKEDA T. A framework for standardized management of intrapartum fetal heart rate patterns. American journal of obstetrics and gynecology 2007;197:26 e1-6. MILLER DA, MILLER LA. Electronic fetal heart rate monitoring: applying principles of patient safety. American journal of obstetrics and gynecology 2012;206:278-83. CLARK SL, HAMILTON EF, GARITE TJ, TIMMINS A, WARRICK PA, SMITH S. The limits of electronic fetal heart rate monitoring in the prevention of neonatal metabolic acidemia. American journal of obstetrics and gynecology 2017;216:163 e1-63 e6. CARBONNE B, BENACHI A, LEVEQUE ML, CABROL D, PAPIERNIK E. Maternal position during labor: effects on fetal oxygen saturation measured by pulse oximetry. Obstet Gynecol 1996;88:797-800. HUMPHRIES A, MIRJALILI SA, TARR GP, THOMPSON JMD, STONE P. The effect of supine positioning on maternal hemodynamics during late pregnancy. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstet 2018:1-8. ABITBOL MM. Supine position in labor and associated fetal heart rate changes. Obstet Gynecol 1985;65:481-6. SIMPSON KR, JAMES DC. Efficacy of intrauterine resuscitation techniques in improving fetal oxygen status during labor. Obstet Gynecol 2005;105:1362-8. KINSELLA SM, PIRLET M, MILLS MS, TUCKEY JP, THOMAS TA. Randomized study of intravenous fluid preload before epidural analgesia during labour. Br J Anaesth 2000;85:311-3. LAPPEN JR, MYERS SA, BOLDEN N, MERCER BM, CHIEN EKS. Maternal Pulse Pressure and the Risk of Postepidural Complications: A Randomized Controlled Trial. Obstet Gynecol 2017;130:1366-76. MIYAZAKI FS, NEVAREZ F. Saline amnioinfusion for relief of repetitive variable decelerations: a prospective randomized study. American journal of obstetrics and gynecology 1985;153:301-6. HOFMEYR GJ, LAWRIE TA. Amnioinfusion for potential or suspected umbilical cord compression in labour. The Cochrane database of systematic reviews 2012;1:Cd000013. PITT C, SANCHEZ-RAMOS L, KAUNITZ AM, GAUDIER F. Prophylactic amnioinfusion for intrapartum oligohydramnios: a meta-analysis of randomized controlled trials. Obstet Gynecol 2000;96:8616. STRONG TH, JR., HETZLER G, SARNO AP, PAUL RH. Prophylactic intrapartum amnioinfusion: a randomized clinical trial. American journal of obstetrics and gynecology 1990;162:1370-4; discussion 74-5. OWEN J, HENSON BV, HAUTH JC. A prospective randomized study of saline solution amnioinfusion. American journal of obstetrics and gynecology 1990;162:1146-9.
39.
40. 41. 42.
43.
44.
45.
46.
47.
48. 49. 50.
51. 52.
53.
XU H, HOFMEYR J, ROY C, FRASER W. Intrapartum amnioinfusion for meconium-stained amniotic fluid: a systematic review of randomised controlled trials. BJOG : an international journal of obstetrics and gynaecology 2007;114:383-90. SPONG CY, OGUNDIPE OA, ROSS MG. Prophylactic amnioinfusion for meconium-stained amniotic fluid. American journal of obstetrics and gynecology 1994;171:931-5. HAMEL MS, ANDERSON BL, ROUSE DJ. Oxygen for intrauterine resuscitation: of unproved benefit and potentially harmful. American journal of obstetrics and gynecology 2014;211:124-7. THORP JA, TROBOUGH T, EVANS R, HEDRICK J, YEAST JD. The effect of maternal oxygen administration during the second stage of labor on umbilical cord blood gas values: a randomized controlled prospective trial. American journal of obstetrics and gynecology 1995;172:465-74. NESTERENKO TH, ACUN C, MOHAMED MA, et al. Is it a safe practice to administer oxygen during uncomplicated delivery: a randomized controlled trial? Early human development 2012;88:67781. QIAN G, XU X, CHEN L, et al. The effect of maternal low flow oxygen administration during the second stage of labour on umbilical cord artery pH: a randomised controlled trial. BJOG : an international journal of obstetrics and gynaecology 2017;124:678-85. RAGHURAMAN N WL, TEMMING LA, WOOLFOLK C, MACONES GA, TUULI MG, CAHILL AG. Effect of Oxygen vs Room Air on Intrauterine Fetal Resuscitation: A Randomized Noninferioirty Clinical Trial JAMA Pediatrics 2018;In Press, Accepted April 2018. KHAW KS, WANG CC, NGAN KEE WD, PANG CP, ROGERS MS. Effects of high inspired oxygen fraction during elective caesarean section under spinal anaesthesia on maternal and fetal oxygenation and lipid peroxidation. Br J Anaesth 2002;88:18-23. HELMERHORST HJ, SCHULTZ MJ, VAN DER VOORT PH, DE JONGE E, VAN WESTERLOO DJ. Bench-to-bedside review: the effects of hyperoxia during critical illness. Critical care (London, England) 2015;19:284. DAMIANI E, DONATI A, GIRARDIS M. Oxygen in the critically ill: friend or foe? Current opinion in anaesthesiology 2018;31:129-35. GARITE TJ, SIMPSON KR. Intrauterine resuscitation during labor. Clinical obstetrics and gynecology 2011;54:28-39. HEUSER CC, KNIGHT S, ESPLIN MS, et al. Tachysystole in term labor: incidence, risk factors, outcomes, and effect on fetal heart tracings. American journal of obstetrics and gynecology 2013;209:32.e1-6. BAKKER PC, KURVER PH, KUIK DJ, VAN GEIJN HP. Elevated uterine activity increases the risk of fetal acidosis at birth. American journal of obstetrics and gynecology 2007;196:313 e1-6. AHMED AI, ZHU L, ALDHAHERI S, SAKR S, MINKOFF H, HABERMAN S. Uterine tachysystole in spontaneous labor at term. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstet 2016;29:3335-9. KULIER R, HOFMEYR GJ. Tocolytics for suspected intrapartum fetal distress. The Cochrane database of systematic reviews 2000:CD000035.
Table 1: Category II EFM features associated with metabolic acidemia
Category II Feature
Adjusted Odds Ratio (95% Confidence Interval)
Prolonged decelerations
3.02 (1.64-5.55)
Tachycardia
2.99 (1.55-5.77)
Recurrent late decelerations
2.46 (1.10-4.29)
Recurrent variable decelerations
1.91 (1.07-3.08)
Total deceleration area >95th percentile
3.79 (2.04-7.04)
Adapted from Cahill, A.G., et al., Association and prediction of neonatal acidemia. Am J Obstet Gynecol, 2012. 207(3): p. 206.e1-8.
Figure 1: Targeted Intrauterine Resuscitation
What is etiology of Category II tracing? Maternal position
Lateral positioning
Uterine activity
Hold oxytocin
Administer terbutaline
Maternal hypovolemia
IV fluid bolus
Umbilical cord compression
Reposition
Amnioinfusion
Maternal hypoxia
Maternal O2 administration