Intrapartum fetal asphyxia: Clinical characteristics, diagnosis, and significance in relation to pattern of development J. A.
LOW
S. R. PANCHAM W.
N.
D.
WORTHINGTON
J.
KARCHMAR
liingston,
PIERCY
Ontario,
Cannda
The clinical and fetal heart rates and acid-base characteristics and their sequelae have been reviewed in 587 patients. The relevant clinical factors in the asphyxia group were the preterm fetus, the intrauterine growth retarded fetus, maternal toxemia, and midforceps delivery. The duration of the developing metabolic acidosis in the asphyxia group ranged from terminal to the last two hours of labor. Marked patterns of total decelerations and moderate and marked patterns of late decelerations are of predictive value in the diagnosis of intrapartum fetal asphyxia with a trend to an increased incidence in the longer duration categories, between four and two hours prior to delivery, and a significant increase in all categories during the last two hours of labor. The significance of intrapartum fetal asphyxia to the newborn infant is evident from the low Apgar scores, increased incidence of moderate and severe respiratory distress syndrome, and central nervous system complications in the asphyxia group in relation to the normal group. (AM. J. OBSTET. GYNECOL. 129: 857,1977.)
PERINATAL ASPHYXIA is in the opinion of many investigators-4 the most important mechanism in injuries to the brain leading to long-term morbidity in surviving newborn infants. The significance of fetal asphyxia in perinatal mortality can be established with some precision by a review of perinatal deaths with postmortem examination. However, the relationship to short- and long-term morbidity is a more elusive question. This is in part due to the fact that the accurate diagnosis of fetal asphyxia is difficult and the response of the particular stressed fetus may be complex, and due in part to the fact that the relationship between the
episode of perinatal asphyxia and the morbidity, observed at a time remote from the event, may be difficult to establish. Thus, studies of the biological processes contributing to and the consequences of fetal asphyxia are of continuing importance. The specific issues are the clinical circumstances that give rise to asphyxia, the severity of asphyxia required to produce injury to the fetus and the newborn infant, and the wide range of physiologic alteration which underlies the diversity of the pathologic changes which occur. The objective of the present study is to provide further data in regard to the clinical circumstances related to the development of intrapartum fetal asphyxia, the fetal heart rate (FHR) characteristics which are of predictive value in the diagnosis, and the neonatal complications that have occurred, the data being derived from patients for whom a diagnosis of asphyxia has been established by means of an acid-base assessment at delivery with the duration of this developing process being documented by means of an acid-base assessment during labor.
.?3?
Low et a!.
Table
I. The
the
last
;nrd
the
Lkcember 15, 1975 Am. j. Obster. Gynecoi.
pH,
two
buffer
hours
threes
base
of labor
categories
(BB)
and
and
oxygen
in the
of the
tension
umbilical
asphyxia
vein
(PO*) and
in fetal
artery
capillary
blood
blood
at delivery
at midlabor
in the
and
normal
during
group
group Normal
group
‘4sphytia
group
Tmminal BB
P NO.
Mean
2 S.D.
Mean
2 S.D.
Mean
k S.D.
No.
Mean
2 S.D.
180 92 142 143 465 465
7.312 7.303 7.299 7.296 7.338 7.272
0.039 0.037 0.050 0.043 0.044 0.044
43.9 43.7 43.4 43.1 42.3 41.0
2.3 2.0 2.2 1.9 1.8 1.6
19.9 19.4 19.2 19.1 27.8 17.6
4.9 4.0 4.4 4.3 5.5 5.2
20 9 37 12 46 46
7.305 7.252 7.282 7.248 7.258 7.146
0.050 0.028 0.053 0.031 0.068 0.070
study
includes
Mid labor 61-120 min. 16-60 min. O-1.’ min. Umbilical vein llmbilical artery
Methods .I‘he
classified
present
tained
587 patients
from
sive
care
unit.
The
the
managed
criteria
requirement
sufficient
for
serial
livery acid-base
group
(465
oping
and
or
the
asphyxia
duration
of the
asphyxia
group.
in the obstetric,
labor,
recorded.
The
have
newborn
been infants
course of to morbidity.
The
FHR
each
been
reviewed The
baseline
FHR,
celerations
been
infant
has
obtained for
each
observations
The
with two-hour made
were
in
FHR
of contractions each
defined with
two-hour
as the a Mr.
period
percentage
deceleration
the and
the
in each
is expressed
labor
the in
last
the
liter
and
2.5
mEq.
liter.’
with
Late
than
or equal
to 30 per
ciated
\vith
a deceleration.
cent
to
blood
buffer
normal bilical
mean. i.e.. artery buffer
1 S.D.
below
the
liter. ‘The
fetal
asphyxia
whom
the
late derate
a decel-
decelerations associ-
two-hour
were
period. in each previousl) classified
cent of contractions were and “marked” if greater of contractions Lnfe
decelerations
were
fer
base
rwol
“asphvxia/onc
the hours an
Volume Number
129 8
Table
II. The
maternal,
fetal,
three
categories
of the
and
the
lntrapartum
and
labor
complications
asphyxia
in the
patients
of the
normal
group
Asphyxia
group
fetal asphyxia
661
group
Normal group (N = 465)
Terminal (N = 46)
(N = 122)
One hour (N = 40)
Two hour.7 (N = 36)
NO.
70
No.
7c
No.
70
No.
5%
284 181
61 39
31 15
67 33
22 18
55 45
26 10
72 28
29 20 15
16 11 8
2 0 2
0 6 2
0 15 5
3 3 0
18 17 35
4 4 7
6 0 6
1 3 0
2 7 0
8 11 14
75 17
16 4
19 9
8 1
20 3
36 4
49 48 26 6 0
10 10 6 1 0
17 13 17 2 4
17 20 22 2 0
19 14 22 3 0
153
33
16
35
17
42
18
50
144 11 10
31 2 2
12 1
33 2 2
4 1 1
11 2 2
20 2 1
56 6 3
418 47
90 10
39 6
85 15
30 9
75 25
29 7
80 20
270 133 1 55
58 29
14 28 3
14 14 2 9
35 35 4 22
II
12
30 61 2 6
30 22 3 44
Parity 0 51 Pregnancy complication Perinatal death Preterm neonate Intauterine growth-retarded neonate Medical complication Hypertension-renal Diabetes Other Obstetrical complication Toxemia A. P. H. Gestational complication Preterm Postterm Intrauterine growth retardation Congenital anomaly Rh-isoimmunization Clznicalfetal distrrcs Amiotic fluid Meconium Labor complications Abnormal uterine action Dystocia Abnormal uterine activity dystocia Anesthesia Regional or local General Delzzvq Spontaneous low forceps Midforceps Breech Ccsarean section
hour”
category
and
demonstrate marked per
significant. centages in the and
decelerations
the
During
the last
three
43 per for
while
the
tern
of total
asphyxia (34
There the
group
percentages
of
decelerations
per were fetus
hours
patients
than
52,
with
and
revealed tients
per-
(38,
than
cent)
three
(19
the
group
greater
61
per
the percentage
40.
pat-
cent)
are
normal
exhibited
in
the
asphyxia
no decelerations,
group two
in in the
of the
of
the
hours
late
“asphyxia/one A review
acid-base
differences patients
and
three
last
four
prior
in
group
these
asphyxia
are
relation
percentages decelerations
the last the three
presented
categories hours
10 pa-
group.
occurred
in of
of labor.
to delivery
of the
characteristics
among
of the
decelerations
associated with of the asphyxia the
in
hour”. and
asphyxia
late
increased
group;
three
deceleration characteristics during of labor in the normal group and
until two
tractions categories
tern
clinical
other
group
group
are
(p < 0.001).
10 patients
fetal
the
Random
and
group,
in “asphyxia/two
no distinctive and
normal
of the
in the
and
categories 3.
(p < O.OOl),
a marked
five
The late eight hours
in per-
categories
and
maternal
group
asphyxia”
hour,”
39 per
a deceleration
asphyxia (27 per
a
statistically
of labor, with
in the
(54, cent)
normal
“terminal
with
and
is not
significantly
the normal
greater
to the
of the
are
group
(37
difference two
category
of patients
associated
categories cent)
significantly group
in relation
however, of contractions
centage
\vhom
of total
respectively) cent):
hour”
percentage
pattern
cent,
“asphyxia/two
an increased
8 1 16
in Fig. both
the
the
asphyxia
Between
the percentages
four of con-
a late deceleration in the three group (4, 3, and 3 per cent) to
1 per
of patients in
the
cent
in
with
a marked
“asphyxia/one
the
normal pathour”
862
Low et al.
NORMAL
$ 3
NO
GROUP
135
87
TERMINAL
180
224
II
ASFtlYXIA
I9
27
ASPHYXIA
35
8
I HOUR I9
13
ASPHYXIA 27
IO
2 HOUR 13
18
31
2
0
6
4
2
Dekv
8
MODERATE
6
4
2
Delw
PATTERN
8
6
MARKED
4
2 D&v
8
6
4
2
Delw
PATTERN
Fig. 2. The average percentage of contractions associated with a deceleration and the range in individual patients and the percentage of patients with a moderate or a marked pattern of total decelerations for each two-hour period in the normal group and the three categories of.the asphyxia group.
Table
III. The
Apgar
group
and
three
the
scores
and
categories
resuscitation of the
characteristics
asphyxia
of the
newborn
infants
Norma.1 group (N = 465)
(I min. and 5 mrr~. J >7 >7 >7 27 Resuscitation with intubation Abnormal first-hour course
and
scow and and and
“asphyxia/two
lation
to those
increased. significant. centages tions
hour” in
the
However, During three
percentages
Yo
No.
383 56 16 4 8 54
84 12 3 1 2 11
27 10 7 2 3 12
(16
group
per
cent)
(4 per
in re-
cent)
are
associated
categories
with
of the
late
asphyxia
are all significantly group (4 per cent) of
patients
with
a
deceleragroup
(9,
greater than (p < 0.001). moderate
or
marked cent) mal
No.
74,
20 12 6 2 4 15
LOW
S. R. PANCHAM W.
N.
D.
WORTHINGTON
J.
KARCHMAR
liingston,
PIERCY
Ontario,
Cannda
The clinical and fetal heart rates and acid-base characteristics and their sequelae have been reviewed in 587 patients. The relevant clinical factors in the asphyxia group were the preterm fetus, the intrauterine growth retarded fetus, maternal toxemia, and midforceps delivery. The duration of the developing metabolic acidosis in the asphyxia group ranged from terminal to the last two hours of labor. Marked patterns of total decelerations and moderate and marked patterns of late decelerations are of predictive value in the diagnosis of intrapartum fetal asphyxia with a trend to an increased incidence in the longer duration categories, between four and two hours prior to delivery, and a significant increase in all categories during the last two hours of labor. The significance of intrapartum fetal asphyxia to the newborn infant is evident from the low Apgar scores, increased incidence of moderate and severe respiratory distress syndrome, and central nervous system complications in the asphyxia group in relation to the normal group. (AM. J. OBSTET. GYNECOL. 129: 857,1977.)
PERINATAL ASPHYXIA is in the opinion of many investigators-4 the most important mechanism in injuries to the brain leading to long-term morbidity in surviving newborn infants. The significance of fetal asphyxia in perinatal mortality can be established with some precision by a review of perinatal deaths with postmortem examination. However, the relationship to short- and long-term morbidity is a more elusive question. This is in part due to the fact that the accurate diagnosis of fetal asphyxia is difficult and the response of the particular stressed fetus may be complex, and due in part to the fact that the relationship between the
episode of perinatal asphyxia and the morbidity, observed at a time remote from the event, may be difficult to establish. Thus, studies of the biological processes contributing to and the consequences of fetal asphyxia are of continuing importance. The specific issues are the clinical circumstances that give rise to asphyxia, the severity of asphyxia required to produce injury to the fetus and the newborn infant, and the wide range of physiologic alteration which underlies the diversity of the pathologic changes which occur. The objective of the present study is to provide further data in regard to the clinical circumstances related to the development of intrapartum fetal asphyxia, the fetal heart rate (FHR) characteristics which are of predictive value in the diagnosis, and the neonatal complications that have occurred, the data being derived from patients for whom a diagnosis of asphyxia has been established by means of an acid-base assessment at delivery with the duration of this developing process being documented by means of an acid-base assessment during labor.
.?3?
Low et a!.
Table
I. The
the
last
;nrd
the
Lkcember 15, 1975 Am. j. Obster. Gynecoi.
pH,
two
buffer
hours
threes
base
of labor
categories
(BB)
and
and
oxygen
in the
of the
tension
umbilical
asphyxia
vein
(PO*) and
in fetal
artery
capillary
blood
blood
at delivery
at midlabor
in the
and
normal
during
group
group Normal
group
‘4sphytia
group
Tmminal BB
P NO.
Mean
2 S.D.
Mean
2 S.D.
Mean
k S.D.
No.
Mean
2 S.D.
180 92 142 143 465 465
7.312 7.303 7.299 7.296 7.338 7.272
0.039 0.037 0.050 0.043 0.044 0.044
43.9 43.7 43.4 43.1 42.3 41.0
2.3 2.0 2.2 1.9 1.8 1.6
19.9 19.4 19.2 19.1 27.8 17.6
4.9 4.0 4.4 4.3 5.5 5.2
20 9 37 12 46 46
7.305 7.252 7.282 7.248 7.258 7.146
0.050 0.028 0.053 0.031 0.068 0.070
study
includes
Mid labor 61-120 min. 16-60 min. O-1.’ min. Umbilical vein llmbilical artery
Methods .I‘he
classified
present
tained
587 patients
from
sive
care
unit.
The
the
managed
criteria
requirement
sufficient
for
serial
livery acid-base
group
(465
oping
and
or
the
asphyxia
duration
of the
asphyxia
group.
in the obstetric,
labor,
recorded.
The
have
newborn
been infants
course of to morbidity.
The
FHR
each
been
reviewed The
baseline
FHR,
celerations
been
infant
has
obtained for
each
observations
The
with two-hour made
were
in
FHR
of contractions each
defined with
two-hour
as the a Mr.
period
percentage
deceleration
the and
the
in each
is expressed
labor
the in
last
the
liter
and
2.5
mEq.
liter.’
with
Late
than
or equal
to 30 per
ciated
\vith
a deceleration.
cent
to
blood
buffer
normal bilical
mean. i.e.. artery buffer
1 S.D.
below
the
liter. ‘The
fetal
asphyxia
whom
the
late derate
a decel-
decelerations associ-
two-hour
were
period. in each previousl) classified
cent of contractions were and “marked” if greater of contractions Lnfe
decelerations
were
fer
base
rwol
“asphvxia/onc
the hours an
Volume Number
129 8
Table
II. The
maternal,
fetal,
three
categories
of the
and
the
lntrapartum
and
labor
complications
asphyxia
in the
patients
of the
normal
group
Asphyxia
group
fetal asphyxia
661
group
Normal group (N = 465)
Terminal (N = 46)
(N = 122)
One hour (N = 40)
Two hour.7 (N = 36)
NO.
70
No.
7c
No.
70
No.
5%
284 181
61 39
31 15
67 33
22 18
55 45
26 10
72 28
29 20 15
16 11 8
2 0 2
0 6 2
0 15 5
3 3 0
18 17 35
4 4 7
6 0 6
1 3 0
2 7 0
8 11 14
75 17
16 4
19 9
8 1
20 3
36 4
49 48 26 6 0
10 10 6 1 0
17 13 17 2 4
17 20 22 2 0
19 14 22 3 0
153
33
16
35
17
42
18
50
144 11 10
31 2 2
12 1
33 2 2
4 1 1
11 2 2
20 2 1
56 6 3
418 47
90 10
39 6
85 15
30 9
75 25
29 7
80 20
270 133 1 55
58 29
14 28 3
14 14 2 9
35 35 4 22
II
12
30 61 2 6
30 22 3 44
Parity 0 51 Pregnancy complication Perinatal death Preterm neonate Intauterine growth-retarded neonate Medical complication Hypertension-renal Diabetes Other Obstetrical complication Toxemia A. P. H. Gestational complication Preterm Postterm Intrauterine growth retardation Congenital anomaly Rh-isoimmunization Clznicalfetal distrrcs Amiotic fluid Meconium Labor complications Abnormal uterine action Dystocia Abnormal uterine activity dystocia Anesthesia Regional or local General Delzzvq Spontaneous low forceps Midforceps Breech Ccsarean section
hour”
category
and
demonstrate marked per
significant. centages in the and
decelerations
the
During
the last
three
43 per for
while
the
tern
of total
asphyxia (34
There the
group
percentages
of
decelerations
per were fetus
hours
patients
than
52,
with
and
revealed tients
per-
(38,
than
cent)
three
(19
the
group
greater
61
per
the percentage
40.
pat-
cent)
are
normal
exhibited
in
the
asphyxia
no decelerations,
group two
in in the
of the
of
the
hours
late
“asphyxia/one A review
acid-base
differences patients
and
three
last
four
prior
in
group
these
asphyxia
are
relation
percentages decelerations
the last the three
presented
categories hours
10 pa-
group.
occurred
in of
of labor.
to delivery
of the
characteristics
among
of the
decelerations
associated with of the asphyxia the
in
hour”. and
asphyxia
late
increased
group;
three
deceleration characteristics during of labor in the normal group and
until two
tractions categories
tern
clinical
other
group
group
are
(p < 0.001).
10 patients
fetal
the
Random
and
group,
in “asphyxia/two
no distinctive and
normal
of the
in the
and
categories 3.
(p < O.OOl),
a marked
five
The late eight hours
in per-
categories
and
maternal
group
asphyxia”
hour,”
39 per
a deceleration
asphyxia (27 per
a
statistically
of labor, with
in the
(54, cent)
normal
“terminal
with
and
is not
significantly
the normal
greater
to the
of the
are
group
(37
difference two
category
of patients
associated
categories cent)
significantly group
in relation
however, of contractions
centage
\vhom
of total
respectively) cent):
hour”
percentage
pattern
cent,
“asphyxia/two
an increased
8 1 16
in Fig. both
the
the
asphyxia
Between
the percentages
four of con-
a late deceleration in the three group (4, 3, and 3 per cent) to
1 per
of patients in
the
cent
in
with
a marked
“asphyxia/one
the
normal pathour”
862
Low et al.
NORMAL
$ 3
NO
GROUP
135
87
TERMINAL
180
224
II
ASFtlYXIA
I9
27
ASPHYXIA
35
8
I HOUR I9
13
ASPHYXIA 27
IO
2 HOUR 13
18
31
2
0
6
4
2
Dekv
8
MODERATE
6
4
2
Delw
PATTERN
8
6
MARKED
4
2 D&v
8
6
4
2
Delw
PATTERN
Fig. 2. The average percentage of contractions associated with a deceleration and the range in individual patients and the percentage of patients with a moderate or a marked pattern of total decelerations for each two-hour period in the normal group and the three categories of.the asphyxia group.
Table
III. The
Apgar
group
and
three
the
scores
and
categories
resuscitation of the
characteristics
asphyxia
of the
newborn
infants
Norma.1 group (N = 465)
(I min. and 5 mrr~. J >7 >7 >7 27 Resuscitation with intubation Abnormal first-hour course
and
scow and and and
“asphyxia/two
lation
to those
increased. significant. centages tions
hour” in
the
However, During three
percentages
Yo
No.
383 56 16 4 8 54
84 12 3 1 2 11
27 10 7 2 3 12
(16
group
per
cent)
(4 per
in re-
cent)
are
associated
categories
with
of the
late
asphyxia
are all significantly group (4 per cent) of
patients
with
a
deceleragroup
(9,
greater than (p < 0.001). moderate
or
marked cent) mal
No.
74,
20 12 6 2 4 15
