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Flow velocity waveforms in the fetal internal carotid artery relative to fetal blood gas and acid-base measurements in normal pregnancy
Early Human Development, 19 (1989) 11l-l Elsevier Scientific Publishers Ireland Ltd.
15
111
EHD 00947
Flow velocity waveforms in the fetal internal carotid artery relative to fetal blood gas and acid-base measurements in normal pregnancy E. Simonazzia, J.W. Wladimiroffb and J. van Eyckb 9epartment of Obstetrics and Gynaecology, Policlinico Monteluce, 06100 Perrugia (Italy) and bDeparttnent of Obstetrics and Gynaecologv, Academic Hospital Rotterdam-DijkZigt, Erasmus University Rotterdam (The NetherIands) Accepted for publication 19 July 1988
Summary Flow velocity waveforms in the fetal internal carotid artery during fetal behavioural state 2F were compared with blood gas and acid-base data from fetal scalp blood samples immediately following artificial rupture of the membranes in 17 normal term pregnancies. The pulsatility index in the fetal internal carotid artery was positively related to PO, and base excess suggesting that also under physiological conditions fetal cerebral vascular resistance may respond to changes in fetal oxygenation. flow velocity waveform; fetal internal carotid artery; fetal oxygenation.
Introduction Blood flow velocity waveforms in the fetal internal carotid artery have been shown to be dependent on fetal behaviour states [2] and helpful in the assessment of fetal growth retardation [ 131. The introduction of cordocentesis has opened the possibility of studying the relation between fetal blood flow and fetal blood gas measurements during normal and reduced fetal oxygenation [9, lo]. In the present study we correlated blood flow velocity waveforms in the fetal internal carotid artery with fetal blood gas and acid-base measurements obtained from scalp samples. Correspondence to: J.W. Wladimiroff, M.D., Professor of Obstetrics & Gynaecology, Academic Hospital Rotterdam-Dijkzigt, Erasmus University Rotterdam, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands. 0378-3782/89/$03.50 0 1989 Elsevier Scientific Publishers Ireland Ltd. Published and Printed in Ireland
112
Patients and Methods Seventeen normal subjects consented to participate in the study which was approved by the ethical committee. Gestational age was 39-40 weeks. Maternal age varied between 18 and 36 years, parity ranged from 1 to 4. No medication or cigarette smoking was allowed from the evening before induction. All subjects were in the supine position during the study period. Induction of labour was carried out for elective reasons. Cervical dilatation at the time of induction ranged between 2 and 3 cm. There were no regular contractions. Both before and after induction of labour there were frequent and periodic gross body-movements, the fetal heart rate (FHR) pattern depicted a heart rate with an oscillation band width > 10 beats/mm and repeated FHR accelerations (FHRP-B) indicating the presence of fetal behavioural state 2F according to the classification of Nijhuis et al. [6]. Labour was induced by artificial rupture of the membranes at 0900 h. Fetal blood was sampled from the scalp and collected into heparinized capillaries for immediate determination of pH, Pco,, PO, on the AVL 940 blood gas analyzer; the base-excess (BE) was calculated from these data. Immediately following scalp sampling flow velocity waveforms in the fetal internal carotid artery were recorded as previously described [12] using a combined 3.5 MHz combined mechanical sector and 3.0 MHz pulsed Doppler ultrasound system (Diasonics CV 400). In each pregnancy a total of five consecutive optimal maximum flow velocity waveforms was selected for quantification of the pulsatility of the waveform by calculating the mean pulsatility index (PI) [3]. This index does not change significantly at 39-40 weeks [ 131. Birthweights were between the 25th and 90th percentile for gestational age according to Kloosterman’s Tables [5] corrected for maternal parity and fetal sex.
Results The fetal heart rate (FHR) pattern before and after fetal scalp sampling was not essentially different. FHR during the flow velocity waveform recordings varied between 120 and 140 beats/min (mean FHR: 130.7 f 5.9 (S.D.) beats/min). The mean and range of the PI, PO,, Pco,, pH and BE values are presented in Table I. There was a significant positive correlation between the PI in the fetal internal carotid artery and PO, (R = 0.61; P< 0.01; Fig. 1) and BE (R = 0.68; P< 0.005; Fig. 2). No correlation could be established for the pH and PCO,. TABLE I Mean and range of PI, pH, Pco,, PO, and BE. PI ICA”
Mean Range WA,
1.3 0.98-1.95 internal carotid artery.
PH
7.35 7.25-7.43
PC% OnmHg)
% (mmHg)
BE
41.2 30-53
32.3 20-48
- 1.6 + 4.2 -
WW)
- 6.9
113
50
. .
45
40 ??
??
0
35
0
0
.
0 ??
30
??
. 25
0 .
.
20
1.1
1.0
1.2
1.3 PI
1.4
1.5
1.6
1.7
ICA
Fig. 1. The PI in the fetal internal carotid artery relative to fetal scalp
B.E.
+4
r2
tmEq/l)
:
-
.
.
-
0-
.
0
.
. -2
PD,.
-
?? .
. .
.
II\ ,.@ , , ‘, , , , , 1.0
1.1
1.2
1.3 PI
1.4
.
1.5
1.6
1.7
ICA
Fig. 2. The PI in the fetal internal carotid artery relative to fetal scalp base excess (BE).
114
Discussion In the present study blood gas and acid-base data were not essentially different from those obtained from the umbilical artery through cordocentesis [9]. Since the FHR-range was narrow (120-140 beats/min), we did not consider it necessary to standardize PI for FHR. All PI values in the fetal internal carotid artery were situated within the normal range (f 2 SD.). Artificial rupture of the membranes, therefore, appeared not to have any detrimental effect on the aforementioned parameters. Data on regulation of cerebral blood flow are only available from animal experimental work and mainly concern chemical, autoregulatory and metabolic regulation [ 11. Both in the human fetus [2] and in the fetal sheep [7] changes in internal carotid blood flow relative to fetal behavioural states have been documented. The observed changes in PI in the fetal internal carotid artery relative to PO, and BE can not be attributed to different behavioural states at the onset of the study, since in all instances state 2F according to the classification of Nijhuis et al. [6] was established. We are aware, though, that fetal eye-movements were not recorded. In a previous study, we were able to demonstrate the presence of the so called ‘brain-sparing’ effect in fetuses which were growth-retarded as a result of impaired utero-placental perfusion [ 131. The positive correlation between PI in the internal carotid artery and fetal PO, in the present study suggests that even under physiological conditions cerebral vascular resistance is affected by changes in fetal oxygenation. Similar observations were done in fetal lambs under controlled conditions, from which it would appear that PO, is an important factor in regulating resistance in the fetal cerebral circulation [4]. This PO, dependency may also explain the documented reduction in PI in the internal carotid artery during the last 4-5 weeks of gestation [l 11, which coincides with a drop in PO, as established in the umbilical artery during cordocentesis 191. Of interest is that whereas the PI in the internal carotid artery is positively correlated to the metabolical component (BE) of the acid-base status, this is not so for the Pco,. Fetal lamb studies have shown that although the fetal cerebral circulation is responsive to Pco, [4,8]; the degree of vasodilatation is only about half of that seen in the adult [RI. Relative to oxygen tension, PCO, is less effective a regulator of fetal cerebral blood flow 141.In conclusion, the present data suggest that also under physiological conditions, the flow velocity waveform in the fetal internal carotid artery may respond to changes in blood gas and acid-base level. References 1 2
3
Bissonette, J.M., Hohimer, A.R., Richardson, B.S. and Machida, C.M. (1984): Regulation of cerebral blood flow in the fetus. J. Dev. Physiol., 6,275-280. Eyck, J. van, Wladimiroff, J.W., Noordam, M.J., Wijngaard, J.A.G.W. van den and Prechtl, H.F.R. (1987): The blood flow velocity waveform in the fetal internal carotid and umbilical artery; its relationship to fetal behavioural states in normal pregnancies at 37-38 weeks of gestation. Br. J. Obstet. Gynaecol.. 94,736-741. Gosling, R.G. and Ring, D.H. (1975): Ultrasound angiology. In: Arteries and Veins, pp. 61-98. Editors: A.W. Marcus and L. Adamson. Churchill Livingstone. Edinburgh.
115
9 10
11
12 13
Jones, M.D. Jr., Rosenberg, A.A., Fraystman, R.J. and Koehler, R.C. (1982) Oxyhemoglobin dissociation and cerebal0, delivery in fetal sheep. Fed. Proc., 41,1527. Kloosterman. G. (1970): On intrauterine growth. Int. J. Gynaecol. Obstet.. 8,895-912. Nijhuis, J.G., Prechtl. H.F.R., Martin, C.B. Jr. and Bots. R.S.G.M. (1982) Are there behavioural states in the human fetus? Early Hum. Dev., 6, 177-195. Richardson, B.S.. Patrick, J.E. and Abduljabbar, H. (1985): Cerebral oxidative metabolism in the fetal lamb: relationship to electrocortical state. Am. J. Obstet. Gynecol., 153,426431. Rosenberg, A.A., Jones, M.D., Jr., Fraystman, R.J., Simmons, M.A. and Molteni, R.A. (1982): Response of cerebral blood flow to changes in pC0, in fetal, newborn and adult sheep. Am. J. Physiol., 242, H862-H866. Soothill, P.W., Nicolaides, K.H.. Rodeck Ch. and Campbell, S. (1986): Effect of gestational age on fetal and intervillous blood gas and acid-base values in human pregnancy. Fetal Ther., 1, 168-175. Soothill, P.W., Nicolaides, K.H., Bilardo, K., Hackett, G.A. and Campbell, S. (1986): Utero-placental blood velocity resistance index and umbilical venous PO,, pCO,, pH, lactate and erythroblast count in growth-retarded fetuses. Fetal Ther., 1, 176-179. Wijngaard, J.A.G.W. van den, Eyck, J. van, Noordam, M. J., Wladimiroff, J.W. and Strik, R. van (1989): The Doppler flow velocity waveforms in the fetal internal carotid artery with respect to fetal behavioural states; A longitudinal study. Biol. Neonate, 53,274-278. Wladimiroff, J.W., Tonge, H.M. and Stewart, P.A. (1986): Doppler ultrasound assessment of cerebral blood flow in the human fetus. Br. J. Obstet. Gynaecol., 93.471-475. Wladimiroff, J.W., Wijngaard, J.A.G.W. van den, Degani, S., Noordam, M. J., Eyck, J. van and Tonge, H.M. (1987): Cerebral and umbilical arterial blood flow velocity waveforms in normal and growth-retarded pregnancies; a comparative study. Obstet. Gynecol.,69,705-709.
15
111
EHD 00947
Flow velocity waveforms in the fetal internal carotid artery relative to fetal blood gas and acid-base measurements in normal pregnancy E. Simonazzia, J.W. Wladimiroffb and J. van Eyckb 9epartment of Obstetrics and Gynaecology, Policlinico Monteluce, 06100 Perrugia (Italy) and bDeparttnent of Obstetrics and Gynaecologv, Academic Hospital Rotterdam-DijkZigt, Erasmus University Rotterdam (The NetherIands) Accepted for publication 19 July 1988
Summary Flow velocity waveforms in the fetal internal carotid artery during fetal behavioural state 2F were compared with blood gas and acid-base data from fetal scalp blood samples immediately following artificial rupture of the membranes in 17 normal term pregnancies. The pulsatility index in the fetal internal carotid artery was positively related to PO, and base excess suggesting that also under physiological conditions fetal cerebral vascular resistance may respond to changes in fetal oxygenation. flow velocity waveform; fetal internal carotid artery; fetal oxygenation.
Introduction Blood flow velocity waveforms in the fetal internal carotid artery have been shown to be dependent on fetal behaviour states [2] and helpful in the assessment of fetal growth retardation [ 131. The introduction of cordocentesis has opened the possibility of studying the relation between fetal blood flow and fetal blood gas measurements during normal and reduced fetal oxygenation [9, lo]. In the present study we correlated blood flow velocity waveforms in the fetal internal carotid artery with fetal blood gas and acid-base measurements obtained from scalp samples. Correspondence to: J.W. Wladimiroff, M.D., Professor of Obstetrics & Gynaecology, Academic Hospital Rotterdam-Dijkzigt, Erasmus University Rotterdam, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands. 0378-3782/89/$03.50 0 1989 Elsevier Scientific Publishers Ireland Ltd. Published and Printed in Ireland
112
Patients and Methods Seventeen normal subjects consented to participate in the study which was approved by the ethical committee. Gestational age was 39-40 weeks. Maternal age varied between 18 and 36 years, parity ranged from 1 to 4. No medication or cigarette smoking was allowed from the evening before induction. All subjects were in the supine position during the study period. Induction of labour was carried out for elective reasons. Cervical dilatation at the time of induction ranged between 2 and 3 cm. There were no regular contractions. Both before and after induction of labour there were frequent and periodic gross body-movements, the fetal heart rate (FHR) pattern depicted a heart rate with an oscillation band width > 10 beats/mm and repeated FHR accelerations (FHRP-B) indicating the presence of fetal behavioural state 2F according to the classification of Nijhuis et al. [6]. Labour was induced by artificial rupture of the membranes at 0900 h. Fetal blood was sampled from the scalp and collected into heparinized capillaries for immediate determination of pH, Pco,, PO, on the AVL 940 blood gas analyzer; the base-excess (BE) was calculated from these data. Immediately following scalp sampling flow velocity waveforms in the fetal internal carotid artery were recorded as previously described [12] using a combined 3.5 MHz combined mechanical sector and 3.0 MHz pulsed Doppler ultrasound system (Diasonics CV 400). In each pregnancy a total of five consecutive optimal maximum flow velocity waveforms was selected for quantification of the pulsatility of the waveform by calculating the mean pulsatility index (PI) [3]. This index does not change significantly at 39-40 weeks [ 131. Birthweights were between the 25th and 90th percentile for gestational age according to Kloosterman’s Tables [5] corrected for maternal parity and fetal sex.
Results The fetal heart rate (FHR) pattern before and after fetal scalp sampling was not essentially different. FHR during the flow velocity waveform recordings varied between 120 and 140 beats/min (mean FHR: 130.7 f 5.9 (S.D.) beats/min). The mean and range of the PI, PO,, Pco,, pH and BE values are presented in Table I. There was a significant positive correlation between the PI in the fetal internal carotid artery and PO, (R = 0.61; P< 0.01; Fig. 1) and BE (R = 0.68; P< 0.005; Fig. 2). No correlation could be established for the pH and PCO,. TABLE I Mean and range of PI, pH, Pco,, PO, and BE. PI ICA”
Mean Range WA,
1.3 0.98-1.95 internal carotid artery.
PH
7.35 7.25-7.43
PC% OnmHg)
% (mmHg)
BE
41.2 30-53
32.3 20-48
- 1.6 + 4.2 -
WW)
- 6.9
113
50
. .
45
40 ??
??
0
35
0
0
.
0 ??
30
??
. 25
0 .
.
20
1.1
1.0
1.2
1.3 PI
1.4
1.5
1.6
1.7
ICA
Fig. 1. The PI in the fetal internal carotid artery relative to fetal scalp
B.E.
+4
r2
tmEq/l)
:
-
.
.
-
0-
.
0
.
. -2
PD,.
-
?? .
. .
.
II\ ,.@ , , ‘, , , , , 1.0
1.1
1.2
1.3 PI
1.4
.
1.5
1.6
1.7
ICA
Fig. 2. The PI in the fetal internal carotid artery relative to fetal scalp base excess (BE).
114
Discussion In the present study blood gas and acid-base data were not essentially different from those obtained from the umbilical artery through cordocentesis [9]. Since the FHR-range was narrow (120-140 beats/min), we did not consider it necessary to standardize PI for FHR. All PI values in the fetal internal carotid artery were situated within the normal range (f 2 SD.). Artificial rupture of the membranes, therefore, appeared not to have any detrimental effect on the aforementioned parameters. Data on regulation of cerebral blood flow are only available from animal experimental work and mainly concern chemical, autoregulatory and metabolic regulation [ 11. Both in the human fetus [2] and in the fetal sheep [7] changes in internal carotid blood flow relative to fetal behavioural states have been documented. The observed changes in PI in the fetal internal carotid artery relative to PO, and BE can not be attributed to different behavioural states at the onset of the study, since in all instances state 2F according to the classification of Nijhuis et al. [6] was established. We are aware, though, that fetal eye-movements were not recorded. In a previous study, we were able to demonstrate the presence of the so called ‘brain-sparing’ effect in fetuses which were growth-retarded as a result of impaired utero-placental perfusion [ 131. The positive correlation between PI in the internal carotid artery and fetal PO, in the present study suggests that even under physiological conditions cerebral vascular resistance is affected by changes in fetal oxygenation. Similar observations were done in fetal lambs under controlled conditions, from which it would appear that PO, is an important factor in regulating resistance in the fetal cerebral circulation [4]. This PO, dependency may also explain the documented reduction in PI in the internal carotid artery during the last 4-5 weeks of gestation [l 11, which coincides with a drop in PO, as established in the umbilical artery during cordocentesis 191. Of interest is that whereas the PI in the internal carotid artery is positively correlated to the metabolical component (BE) of the acid-base status, this is not so for the Pco,. Fetal lamb studies have shown that although the fetal cerebral circulation is responsive to Pco, [4,8]; the degree of vasodilatation is only about half of that seen in the adult [RI. Relative to oxygen tension, PCO, is less effective a regulator of fetal cerebral blood flow 141.In conclusion, the present data suggest that also under physiological conditions, the flow velocity waveform in the fetal internal carotid artery may respond to changes in blood gas and acid-base level. References 1 2
3
Bissonette, J.M., Hohimer, A.R., Richardson, B.S. and Machida, C.M. (1984): Regulation of cerebral blood flow in the fetus. J. Dev. Physiol., 6,275-280. Eyck, J. van, Wladimiroff, J.W., Noordam, M.J., Wijngaard, J.A.G.W. van den and Prechtl, H.F.R. (1987): The blood flow velocity waveform in the fetal internal carotid and umbilical artery; its relationship to fetal behavioural states in normal pregnancies at 37-38 weeks of gestation. Br. J. Obstet. Gynaecol.. 94,736-741. Gosling, R.G. and Ring, D.H. (1975): Ultrasound angiology. In: Arteries and Veins, pp. 61-98. Editors: A.W. Marcus and L. Adamson. Churchill Livingstone. Edinburgh.
115
9 10
11
12 13
Jones, M.D. Jr., Rosenberg, A.A., Fraystman, R.J. and Koehler, R.C. (1982) Oxyhemoglobin dissociation and cerebal0, delivery in fetal sheep. Fed. Proc., 41,1527. Kloosterman. G. (1970): On intrauterine growth. Int. J. Gynaecol. Obstet.. 8,895-912. Nijhuis, J.G., Prechtl. H.F.R., Martin, C.B. Jr. and Bots. R.S.G.M. (1982) Are there behavioural states in the human fetus? Early Hum. Dev., 6, 177-195. Richardson, B.S.. Patrick, J.E. and Abduljabbar, H. (1985): Cerebral oxidative metabolism in the fetal lamb: relationship to electrocortical state. Am. J. Obstet. Gynecol., 153,426431. Rosenberg, A.A., Jones, M.D., Jr., Fraystman, R.J., Simmons, M.A. and Molteni, R.A. (1982): Response of cerebral blood flow to changes in pC0, in fetal, newborn and adult sheep. Am. J. Physiol., 242, H862-H866. Soothill, P.W., Nicolaides, K.H.. Rodeck Ch. and Campbell, S. (1986): Effect of gestational age on fetal and intervillous blood gas and acid-base values in human pregnancy. Fetal Ther., 1, 168-175. Soothill, P.W., Nicolaides, K.H., Bilardo, K., Hackett, G.A. and Campbell, S. (1986): Utero-placental blood velocity resistance index and umbilical venous PO,, pCO,, pH, lactate and erythroblast count in growth-retarded fetuses. Fetal Ther., 1, 176-179. Wijngaard, J.A.G.W. van den, Eyck, J. van, Noordam, M. J., Wladimiroff, J.W. and Strik, R. van (1989): The Doppler flow velocity waveforms in the fetal internal carotid artery with respect to fetal behavioural states; A longitudinal study. Biol. Neonate, 53,274-278. Wladimiroff, J.W., Tonge, H.M. and Stewart, P.A. (1986): Doppler ultrasound assessment of cerebral blood flow in the human fetus. Br. J. Obstet. Gynaecol., 93.471-475. Wladimiroff, J.W., Wijngaard, J.A.G.W. van den, Degani, S., Noordam, M. J., Eyck, J. van and Tonge, H.M. (1987): Cerebral and umbilical arterial blood flow velocity waveforms in normal and growth-retarded pregnancies; a comparative study. Obstet. Gynecol.,69,705-709.