Graphic monitoring of labour B. NORMAN BARWIN, BAO, B CH, MD, MRCOG, FACOG; ANTHONY DEMPSEY, MB, CH B; GILLES D. HURTEAU, MD, FRCS[C]

The parturograph is a composite record designed for the monitoring of fetal and maternal well-being and the progress of labour. It permits the early recognition of abnormalities and pinpoints the patients who would benefit most from intervention. Observations are made from the time of admission of the mother to the caseroom and recorded graphically. Factors assessed include fetal heart rate, maternal vital signs and urine, cervical dilatation, descent of the presenting fetal part, and frequency, duration and intensity of uterine contractions. Le parturographe est un bilan multiple destind a Ia surveillance du bien-6tre maternel et foetal pendant le d.roulement du travail. II permet de reconnaitre rapidement les anomalies et de designer les patlentes les plus susceptibles de ben6ficier d'une Intervention. Les observations sont faltes das le moment de l'entr6e de Ia mare a Ia salle d'examen et enreglstr6es graphiquement. Les facteurs 6valu6s comprennent le rythme du coeur foetal, les signes vitaux maternels, Ia dilatation du col, Ia descente du b6b., et Ia fr6quence, Ia dur6e et l'intenslt6 des contractions ut6rines.

In modern obstetric practice it is essential that every attempt be made to ensure that the infant is born alive and that the potential for future intellectual growth is intact. Of the phases of intrauterine life from implantation to birth it is often the latter that is responsible for much preventable morbidity and mortality. The graphic analysis of labour has become a necessary part of the management of a patient in labour. We have designed a labour observaFrom the high-risk pregnancy unit, Ottawa General Hospital and department of obstetrics and gynecology, University of Ottawa Reprint requests to: Dr. B.N. Barwin, Ottawa General Hospital, 43 Bruyere St., Ottawa, Ont. KIN 5C8

tion chart, the "parturograph" (Fig. 1), based on the work of Friedman,1 Philpott2 and Notelovitz' and our clinical experience, to provide a graphic record of essential features of labour and to plot observed values against predicted values of normal. It is a reproducible method of documenting the progress of labour and simplifies teaching. The main advantage is that it permits the early recognition of labour abnormalities and pinpoints the patients who would benefit most from intervention. Basis of the monitoring system The three important aspects of labour to be monitored are (a) fetal well-being (the presence or absence of fetal distress), (b) maternal well-being (the response of the mother to the stress of labour) and (c) the progress of labour. Fetal well-being The behaviour of the fetal heart rate

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(FHR) during uterine contractions is an indication of the integrity of fetoplacental perfusion and of the response of the fetus to stress. Continuous FHR monitoring has been made possible with the development of the fetal cardiotachograph. Characteristic FHR patterns have been described by Hon4 and Caldeyro-Barcia and colleagues.5 The interpretation of these tracings depends on the following features: 1. Baseline FHR between contractions. 2. Increase or decrease of FHR during a contraction. 3. The timing of this change in relation to the contraction. 4. Recovery of FHR at the end of the contraction. 5. Beat-to-beat variation of FHR. Beard and colleagues have shown that important fetal acidemia and hypoxia are associated with baseline fetal tachycardia (heart rate greater than 160 beats/mm); appearance of late decelerations, with progressive increase in amplitude of the decelerations and repetition of this pattern; and, finally, baseline bradycardia (heart rate less than 120 beats/mm). Irregularities in FHR can thus be an early and fairly accurate sign of fetal distress, particularly if there are associated "risk" factors. Meconium staining of the amniotic fluid is a poor reflection of fetal acidbase status but fresh meconium may be an early warning sign and its presence should be recorded on the parturograph. Maternal well-being

FIG. 1-Parturograph: solid and broken curves represent normal progress of labour in multiparous and nulliparous women, respectively.

Labour imposes considerable physiological and psychological stress on the mother. If the supply of energy from carbohydrates is insufficient, fat is metabolized and ketosis develops. This may be detected by the presence of acetone in the maternal urine and clinical signs of ketosis and dehydration. The pulse rate is increased during labour but a rate exceeding 100 beats!

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mm may indicate maternal distress. The systolic blood pressure may increase by 10 to 20 mm Hg with each contraction. An increase in temperature should not occur unless there is ketosis, when the temperature may increase 0.5 0C, or intrauterine infection. Intrapartum proteinuria has been noted in 30% of patients without proteinuria on admission;7 urinary protein concentration should be less than 0.5 gIl and urine output should be normal provided hydration is adequate. Values for variables should be recorded on the chart and treatment instituted, as required, with sedation, analgesia, local anesthesia or intravenous dextrose solution (for adequate hydration). Treatment, in relation to time, should also be recorded. Progress of labour The average duration of the first stage of labour in healthy primigravidas is 12 hours.7 Prolongation of this stage in the absence of any obvious abnormality such as fetal malpresentation or disproportion is accepted by many obstetricians with "watchful expectance". Factors to account for the inefficient uterine action must be sought because early treatment will benefit both mother and fetus. Cervical dilatation: Friedman1 first offered a clear picture of this stage when he documented graphically cervical dilatation with time. From this parturograph he delineated the phases of labour onset, latent phase, active phase, rapid ascent and deceleration just before full dilatation. He showed that the mean duration of the latent phase - that is, the period when the cervix dilates to 2.5 cm - is 7 hours; dilation to 4 cm is accelerated, taking 90 to 120 minutes; and in the "active" phase, dilation (from 4 to 8 cm) progresses at 1.2 and 1.5 cm/h in primigravidas and multiparas, respectively. During the last two phases the patient is aware of contractions; their frequency and duration should be recorded. Once active labour has been established, cervical stasis (failure of the cervix to dilate progressively) indicates some abnormality, possibly cephalopelvic disproportion or incoordinate uterine action. Thus graphic analysis of the progress of labour permits earlier recognition of labour abnormalities and pinpoints the patients who would benefit from intervention. Few people dispute the value of this procedure; opinions vary instead on the timing and aggressiveness of intervention. Descent of the presenting part: Cervical dilatation is assessed in relation to descent of the presenting part. The position of the presenting part above or below the ischial spines ("zero sta-

tion") is indicated as -1, -2 or -3 cm, or +1, +2 or +3 cm, respectively. Descent depends on the size and position of the presenting part, the diameter and shape of the maternal bony pelvis, the resistance of the soft tissues of the pelvic floor and the efficiency of uterine contractions. Friedman and Sachtleben8 showed that when descent of the fetal head in a primigravida was arrested for an hour or more during active labour cephalopelvic disproportion was the cause in 26% of instances. Moreover, the incidence of respiratory depression of the infant at birth and perinatal mortality were higher when descent of the fetal head was delayed. The head is considered to be engaged when the maximum diameter (biparietal) of the fetal skull has passed the brim of the pelvis and the vertex is at the level of the ischial spines. However, caput formation and moulding may give false impressions of the degree of descent; hence it is important to record the degree of moulding and how much of the head is palpable in the lower abdomen. Uterine contractions: Frequency and duration of the contractions are recorded and their intensity is indicated as poor, mild, moderate or strong. When contractions are painful the pain is usually proportional to their intensity and the intrauterine pressure. Pain is usually experienced when the intrauterine pressure reaches 25 to 35 mm Hg - that is, when the contractions are well established. The use of the tocodynamometer has proven a reliable method of assessing the strength and frequency of contractions. Abdominal palpation and observation of the patient's response to the contractions as they increase progressively in strength and frequency will indicate a progressing, coordinated labour. The ideal contraction should include the entire uterus at the peak of the contraction and should last 40 to 90 seconds. Recording and interpretation of parturograph When the patient is admitted to the caseroom the maternal height, age, date of last menstrual period, expected date of delivery, and numbers of pregnancies, livebirths, stillbirths and abortions are noted on the chart, as are any medical or obstetric complications. The patient is then classified as being "normal" or "at risk". At the time of admission, "zero hour", baseline recordings are made of pulse, blood pressure and temperature, and whether the urine contains protein or acetone. An initial vaginal examination is carried out and the dilatation of the cervix and station of the presenting part are noted.

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The frequency of observations will vary according to the clinical situation. During normal labour the following observations are made half-hourly and the time noted: maternal pulse; blood pressure; frequency, duration and strength of uterine contractions; and fetal heart rate. Vaginal examination to monitor the level of the presenting part and cervical dilatation is performed every 2 hours. With this composite recording of the essential features of fetal and maternal well-being and progress of labour, the overall progress at any time can be assessed. If any abnormality is detected, more frequent observations are required and are noted in the appropriate space. The chart is also used for prescribing analgesics, sedatives and any other medication or treatment. The first warning of failure of progress in labour may be a delay of cervical dilatation. If the clinical pattern of uterine activity is not compatible with normal progress of labour, adequate steps must be taken. Weak, ineffectual contractions of short duration may require stimulation with oxytocin, provided there is no major cephalopelvic disproportion. Secondary cervical stasis and failure of the head to descend in the presence of moulding are warning signs of cephalopelvic disproportion. If there is evidence of fetal distress as indicated by deviation from the characteristic FHR pattern, a blood sample should be obtained from the fetal scalp for estimation of pH; if no correctable factor is present, delivery of the baby is indicated. Conclusion Graphic analysis of labour is a necessary part of the management of labour. The parturograph is a simple aid in monitoring labour. Provided observations are recorded meticulously, the graph's rational interpretation will permit early detection of developing abnormalities, so that corrective measures can be instituted. References 1. FRIEDMAN EA: Labour: Clinical Evaluation and Management, New York, Meredith, 1967, p 89 2. PHILPOTT RH: Graphic records in labour. Br Med 1 4: 163, 1972 3. Nom.ovrrz M: Graphic records in labour. S Ajr I Obstet Gynecol 11: 3, 1973 4. HON EH: Observations on pathologic fetal bradycardia. Am I Obstet Gynecol 77: 1084, 1959 5. CALDEYRO-BARCIA MENDEX-VAVER R, C, PosEIRA JJ, et al: in The Heart and Circulation of the Newborn and Infant, CASSELS DE (ed), New York, Grune, 1966, chap 10, p 7 6. BEARD RW, FILSHIE GM, KNIGHT CA, et al: The significance of the changes in the continuous fetal heart rate in the first stage of labour. I Obstet Gynaecol Br Commonw 78: 865, 1971 7. GREENHILL JP: Obstetrics, 13th ed, London, Saunders, 1965, p 346 8. FRIEDMAN EA, SACHTLEBEN MR: Dysfunctional labor. Obstet Gynecol 17: 135, 1961

Graphic monitoring of labour.

The parturograph is a composite record designed for the monitoring of fetal and maternal well-being and the progress of labour. It permits the early r...
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