Fetal Health Surveillance (FHS): Part 1 - Introduction Maternal Newborn Orientation Learning Module Reproductive Care Program of Nova Scotia Revised July, 2013

Objectives Review physiology influencing the fetal heart rate Describe tools for fetal surveillance Doppler The electronic fetal monitor (EFM) Review Intermittent Auscultation (IA) of the FHR

References: www.sogc.org

Physiology related to the FHR Intrinsic and extrinsic factors Homeostatic mechanisms

Internal mechanisms of FHR control Intrinsic Factors Internal mechanisms of FHR control Central Nervous System Medulla oblongata – controls HR, BP Mid-brain to cortex – controls FHR and changes that occur in response to fetal states and activity Autonomic Nervous System Sympathetic -  FHR, strength of cardiac contractions Parasympathetic -  FHR via vagus nerve

Intrinsic factors Hormones - catecholamines Epinephrine  HR, BP, stroke volume and cardiac output Norepinephrine  blood flow to vital organs during hypoxemia Angiotensin, aldosterone potent vasoconstrictors acting in response to hemorrhage or hypoxemia

Intrinsic factors Baroreceptors Chemoreceptors ‘pressure receptors’ located in aortic arch and carotid respond to changes in BP to  or  the FHR Chemoreceptors located in aortic arch, carotid, and medulla oblongata respond to changes in pO2 and pCO2 to  or  the FHR

Intrinsic factors Fetal behavioral states and development Quiet/active sleep, awake Advancing gestation Used with permission, 2013 NCAST University of Washington

Extrinsic factors Factors in the fetal environment that affect oxygen availability, fetal well-being, and the FHR Maternal health Placenta Umbilical cord

Extrinsic factors Maternal influences: pO2 – respiratory status, smoking O2 carrying capacity – Hgb, blood volume Uterine blood flow – circulation, venous return Uterine contractions – normal, tachysystole, hypertonus

Extrinsic factors - placenta Maternal arterioles

Extrinsic factors Normal placenta Calcified placenta

Extrinsic factors

Umbilical Cord Abnormalities Nuchal cord True knot

Extrinsic factors Umbilical cord influences

Homeostatic Mechanisms Regulating mechanisms that allow the fetus to adapt to the stresses of labour and birth Reflex responses Normal responses Compensatory responses Protect fetal integrity Dependent on fetal reserve Decompensation

Methods and tools for FHS William’s Obstetrics

1 2 Leopold’s Maneuver - an essential skill 4 3 William’s Obstetrics

Fetal Health Surveillance - Principles SOGC advises: (2007) ‘The normal, healthy fetus is well-equipped to withstand the repeated, transient hypoxia associated with labour contractions.’ ‘Intermittent auscultation (IA) is the preferred method of fetal surveillance for healthy women without risk factors for adverse outcomes’.

Decisions around methods of FHS Always consider a woman’s choice Use of EFM supported for pregnancies with complications Hypertension  Postmaturity >42 weeks  IUGR  Prematurity Multiple pregnancies Continuous EFM for augmentation / ‘mostly continuous’ for induction

Auscultation Auscultate the FHR q 15 minutes in active labour, q 5 minutes during second stage once active pushing has begun

Auscultation procedure 60-second count ‘results in greatest accuracy’ Baseline rate is assessed between contractions. Check maternal pulse to confirm FHR Record rate, rhythm (regular or irregular), and accelerations (abrupt increases) and/or decelerations (gradual or abrupt)

Ausculation classification Normal FHR: FHR 110 to 160 Regular rhythm Accelerations Abnormal FHR: Outside normal range Decelerations

Documentation – NS Partogram (RCP) http://rcp.nshealth.ca/publications/labour-partogram-companion-guide

If the FHR is abnormal on auscultation…. ‘Auscultate the FHR after the next contraction to confirm the characteristics’ (SOGC) Assess potential causes – attempt to eliminate or reduce the effect Recheck maternal pulse, V/S Initiate EFM

Part 2… Analysis and interpretation of EFM tracings Interventions recommended in the event of atypical or abnormal tracings

Thank you! We welcome your feedback. Please take a few moments to complete a short evaluation: http://rcp.nshealth.ca/education/learning-modules/evaluation If you have any questions, please contact the RCP office at rcp@iwk.nshealth.ca or 902-470-6798