ADONIS 030654569 100203B
British Journul of Obstetrics und Gymecology August 1991, Vol. 98, pp. 820-8823
Relation of fetal blood gases and data from computerassisted analysis of fetal heart rate patterns in small for gestation fetuses LUCIA S. M. RIBBERT, ROSALINDE J. M. SNIJDERS, KYPROS H. N I C O L A I D E S , G E R A R D H. A. VTSSER Summary. Fetal heart rate ( F H R ) monitoring and computer-assisted analysis were performed immediately before cordocentesis in 25 severely small-for-gestational age fetuses. T h e r e werc significant associations between FHR vilriation and both umbilical vein blood Po, ( r = 0 . 6 6 ) and pH (r=0.69).However, t h e wide scatter ofvalucs around t h e regression lines prevented accurate prediction of fetal blood gases from FHR patterns. Nevertheless, FHR variation I0 bcatdmin and duration 2 1 5 s) and dccclerations (amplitude >20 bcatshin and duration 230 s) was calculated. Whcn largc decelerations and accelerations wcrc absent, smaller dccclerations (210 beatshin, >60k) were also identiticd. Since in 95-97"/0 of normal third trimcstcr Zetuses thc FHR variation is >30 ms, this value was taken to bc thc lower limit of normality for our study (Dawcs et nl. 1985). Cordocentesis was performed as an outpatient proccdurc without matcrnal fasting, sedation or fctal paralysis (Nicolaides eta/. 1986). The cord vcssel sampled was identified as artery or vein by thc ultrasonic detection of the turbulence produced after the intravascular injection of normal
salinc (400 PI). In this study, only pregnancies in which the Umbilkdl vein was samplcd were included. Fetal blood (200 pl) was aspirated into heparinized syringes and blood gas measuremcnts used a Radiometer ABL 330 analyzer (Copenhagen, Denmark). The fetal tempcrature was assumed to bc 37°C (Soothill et al. 1987). Since in normal pregnancy thc umbilical vein blood Po?and pH dccrcase with gestation (Nicolaides rt al. 1989a). the results for the small for gcstational age (SGA) fetuses were expressed as the numbcr of SD by which the measured valucs differed from the appropriate normal mean for gestation (delta Poz and delta pH rcspcctively in SDs). Regrcssion analysis and unpaired Student's t-test were used to dcterminc the signiticance of thc rclation betwccn FHR variables and delta Po,, or delta pH. Results In this group of 25 SGA features, the mean Po? was 2.0 SD (range 0-2-3.7 SD) and the mcan pH 3.4 SD (range 0-7-10-7 SD) below the respectivc normal mean for gestation (Fig. 2). In 20 (80%) of the fetuses the Po2and/or pH were below the 5th centile for gestation. FHR variation was significantly associated with both dclta Po, ( n = 2 5 , r=0.66, p
British Journul of Obstetrics und Gymecology August 1991, Vol. 98, pp. 820-8823
Relation of fetal blood gases and data from computerassisted analysis of fetal heart rate patterns in small for gestation fetuses LUCIA S. M. RIBBERT, ROSALINDE J. M. SNIJDERS, KYPROS H. N I C O L A I D E S , G E R A R D H. A. VTSSER Summary. Fetal heart rate ( F H R ) monitoring and computer-assisted analysis were performed immediately before cordocentesis in 25 severely small-for-gestational age fetuses. T h e r e werc significant associations between FHR vilriation and both umbilical vein blood Po, ( r = 0 . 6 6 ) and pH (r=0.69).However, t h e wide scatter ofvalucs around t h e regression lines prevented accurate prediction of fetal blood gases from FHR patterns. Nevertheless, FHR variation I0 bcatdmin and duration 2 1 5 s) and dccclerations (amplitude >20 bcatshin and duration 230 s) was calculated. Whcn largc decelerations and accelerations wcrc absent, smaller dccclerations (210 beatshin, >60k) were also identiticd. Since in 95-97"/0 of normal third trimcstcr Zetuses thc FHR variation is >30 ms, this value was taken to bc thc lower limit of normality for our study (Dawcs et nl. 1985). Cordocentesis was performed as an outpatient proccdurc without matcrnal fasting, sedation or fctal paralysis (Nicolaides eta/. 1986). The cord vcssel sampled was identified as artery or vein by thc ultrasonic detection of the turbulence produced after the intravascular injection of normal
salinc (400 PI). In this study, only pregnancies in which the Umbilkdl vein was samplcd were included. Fetal blood (200 pl) was aspirated into heparinized syringes and blood gas measuremcnts used a Radiometer ABL 330 analyzer (Copenhagen, Denmark). The fetal tempcrature was assumed to bc 37°C (Soothill et al. 1987). Since in normal pregnancy thc umbilical vein blood Po?and pH dccrcase with gestation (Nicolaides rt al. 1989a). the results for the small for gcstational age (SGA) fetuses were expressed as the numbcr of SD by which the measured valucs differed from the appropriate normal mean for gestation (delta Poz and delta pH rcspcctively in SDs). Regrcssion analysis and unpaired Student's t-test were used to dcterminc the signiticance of thc rclation betwccn FHR variables and delta Po,, or delta pH. Results In this group of 25 SGA features, the mean Po? was 2.0 SD (range 0-2-3.7 SD) and the mcan pH 3.4 SD (range 0-7-10-7 SD) below the respectivc normal mean for gestation (Fig. 2). In 20 (80%) of the fetuses the Po2and/or pH were below the 5th centile for gestation. FHR variation was significantly associated with both dclta Po, ( n = 2 5 , r=0.66, p
