Perinatal asphyxia in a rural Nigerian hospital: Incidence and determinants of early outcome

Abstract

BACKGROUND:

Perinatal asphyxia is an important cause of morbidity and mortality in the neonatal period, accounting for 20–30% of neonatal mortality. A substantial proportion (estimated at 26%) of the 1 million annual intrapartum stillbirths result from asphyxia. Probably higher than the mortality is the plethora of morbidity associated with asphyxia, especially long term neuro-developmental problems including cerebral palsy.

The real burden of perinatal asphyxia is difficult to establish because of paucity of information from the rural communities where the majority of neonatal morbidity and deaths occur. Extended Apgar scores and HIE grade have been identified as predictive tools in prognosticating asphyxia, however HIE staging require a certain level of medical expertise which is not widely available.

AIM:

To determine the incidence of asphyxia, the mortality rate and factors associated with mortality in Irrua Specialist Hospital.

METHOD:

It was a descriptive, retrospective study of neonates admitted into the special care baby unit (SCBU) between October 2013 and September 2014 with diagnosis of perinatal asphyxia. Data was obtained from babies’ and mother’s case notes. The outcome was classified as survived or died.

RESULTS:

Perinatal asphyxia accounted for 45 out of 347 (13%) of admissions within the review period. The mean gestational age and birth weight of the subjects were 39.2±2.2 weeks and 3020±520 grams respectively. The mortality rate was 31.1% and the factors significantly associated with mortality include lack of antenatal care and HIE stage III.

CONCLUSION:

The burden of perinatal asphyxia in Irrua Specialist Hospital is comparable to figures from similar settings in the developing world. Lack of antenatal care and HIE stage III are associated with mortality. Continuous efforts should be made to improve the uptake of antenatal care and high risk pregnancies should be delivered in centres with facilities for neonatal care.

Keywords

Asphyxia incidence outcome

1 Introduction

Perinatal asphyxia is an important cause of morbidity and mortality in the neonatal period, accounting for 20–30% of neonatal mortality [1, 2]. It is also an indicator of the social, educational and economic standards of a community [3]. A substantial proportion (estimated at 26%) of the 1 million annual intrapartum stillbirths result from asphyxia [4]. Probably higher than the mortality is the plethora of morbidity associated with asphyxia, especially long term neuro-developmental problems including cerebral palsy.

The death of an infant from perinatal asphyxia is frequently avoidable. In developed countries with optimally-functional health services, these deaths are rare and ways to prevent them are widely understood and applied [3]. Optimal antenatal care, effective resuscitation of compromised neonates and therapeutic hypothermia are modalities which have significantly improved the outlook of affected babies in developed countries.

In developing countries however, mortality is still unacceptably high, ranging from 4.6 per1000 in Cape Town, South Africa to 26 per 1000 in Nigeria. Perinatal asphyxia is the cause of 23% of all neonatal deaths worldwide (WHO, 2005). It is the fifth largest cause of the death of children younger than 5 years of age [5].

Perinatal asphyxia carries high morbidity and mortality. The reported mortality rate is about 20% in full-term asphyxiated infants, while the incidence of neurological impairments in survivors is estimated to be about 25% [6 –8]. The real burden is difficult to establish because of paucity of information from the rural communities where the majority of neonatal morbidity and deaths occur. Extended Apgar scores and HIE stage have been identified as predictive tools in prognosticating asphyxia, however HIE staging require a certain level of medical expertise which is not widely available.

This study describes the incidence of asphyxia in Irrua Specialist Hospital, the mortality rate as well as the socio-demographic and clinical determinants of mortality.

1.1 Aim

To determine the incidence of asphyxia, the mortality rate and factors associated with mortality in Irrua Specialist Hospital.

2 Subjects and methods

Irrua Specialist Hospital is located in a suburban part of South-South Nigeria. The special care baby unit (SCBU) has a capacity for 26 neonates; with an average annual admission rate of 500. Passive cooling was instituted for some of the babies admitted within six hours of birth. The neonatal unit is manned by pediatric and general nurse practitioners as well as trainees and consultant pediatricians. There is no facility for nitric oxide, extracorporeal membrane oxygenation (ECMO) or therapeutic hypothermia. The labor ward is a major referral center for high risk pregnancies and is staffed by midwives, trainees and consultant obstetricians. This is a descriptive, retrospective study of neonates admitted into SCBU between October 2013 and September 2014. Some of the babies were referred from peripheral hospitals. Babies with diagnosis of perinatal asphyxia were recruited. Data was obtained from the case notes. The data obtained include demographic characteristics such as gender, gestational age, birthweight, postnatal age at admission, presence and stage of encephalopathy were documented. HIE was graded using the Sarnat and Sarnat staging [9]. Outcome was classified as survived or died. Maternal characteristics such as age, level of education, booking status and mode of delivery were also recorded.

2.1 Data handling

Data was entered onto an MS-Excel spreadsheet and then imported to the statistical software SPSS version 20 for analysis using standard statistical methods. The analysis of patient demographics and baseline outcome variables was summarised using descriptive study methods and expressed as means (±standard deviations (SDs)) and frequencies and percentages for categorical variables. Discharged and deceased subjects were compared; p value less than 0.05 was considered to be statistically significant.

2.2 Subjects

All neonates with the diagnosis of perinatal asphyxia based on APGAR scores of ≤3 at 5 minutes of age as defined by the task force American College of Obstetricians and Gynecologists and The American Academy of Pediatrics were eligible for inclusion [10]. Babies with other causes of low Apgar scores other than perinatal asphyxia, such as obvious congenital abnormalities of the central nervous system, sedation and conditions incompatible with life, were excluded from the study.

2.3 Results

The details of the characteristics of the subjects and mothers are shown in Tables 1 and 2. Sixty percent were inborn and 40% were referrals. Of the total patients, 62% were males. Term infants were 71.1%, while the preterm and post-term accounted for 15.6 and 13.3% respectively.

Table 1
Demographic characteristics of the subjects

Infant characteristics Frequency (%)

Gender

Male 28 (62)

Female 17 (38)

Gestational age (wks)

<37 7 (15.6)

37–42 32 (71.1)

>42 6 (13.3)

Birth weight (gm)

<2500 4 (8.9)

2500–3999 37 (82.2)

≥4000 4 (8.9)

Infant characteristics	Frequency (%)
Gender
Male	28 (62)
Female	17 (38)
Gestational age (wks)
<37	7 (15.6)
37–42	32 (71.1)
>42	6 (13.3)
Birth weight (gm)
<2500	4 (8.9)
2500–3999	37 (82.2)
≥4000	4 (8.9)

Table 2

Demographic and obstetric characteristics of the mothers

Maternal characteristics	Frequency (%)
Age(yrs)
<20	5 (11.1)	mean: 28.8±5.6
21 –30	25 (55.6)
31 –40	15 (33.3)
LOE Primary	17 (37.8)
Secondary	19 (42.2)
Tertiary	9 (20)
Booking status Booked	10 (22.2)
Un-booked	17 (37.8)
Outborn	18 (40)
Mode of delivery SVD	24 (53.3)
Assisted VD	1 (2.2)
CS	20 (44.4)

LOE: level of education, SVD: spontaneous Vaginal Delivery, VD: vaginal Delivery, CS:caeserian section.

Fifteen (33%) had hypoxic ischemic encephalopathy of different severity, three (6.7%) had disseminated intravascular coagulation (DIC). The mortality rate was 31.1% and the factors significantly associated with mortality include lack of antenatal care, outborrn and HIE stage III. Details of the factors affecting the outcome are in Tables 3 and 4.

Table 3

Relationship between HIE and outcome

Outcome (n = 45)	Survived	Died	Total
No HIE	25 (83.6)	5 (16.7)	30
HIE II	3 (75)	1 (25)	4
HIE III	3 (27.3)	8 (72.7)	11

P < 0.05.

Table 4

Relationship between maternal characteristics and neonatal outcome

Maternal characteristics	Outcome
	Survived	Died	P value
Age(yrs)
<20	3 (6.7)	2 (4.4)	0.81
21 –30	18 (40)	7 (15.6)
31 –40	10 (22.2)	5 (11.1)
Booking Status
Inborn
Booked	5 (11.1)	7 (15.6)	0.02
Un-booked	3 (6.7)	12 (26.7)
Mode of delivery
Vaginal	17 (37.8)	8 (18)	0.66
Caesarean	15 (33.3)	5 (11.1)

3 Discussion

From this study, asphyxia is a major cause of neonatal admission in our centre. It accounted for 13% of the admissions which was lower than 25% and 30% reported in Pakistan and Enugu, Nigeria respectively [11, 12]. The incidence of asphyxia from different studies is quite difficult to compare because of the variable criteria used in defining it based on APGAR scores. Some centres still use the first minute score and some use scores less than 7 at the fifth minute to define asphyxia. Furthermore the assessment of an infant’s Apgar score is quite subjective and fraught with inter-observer variation.

The gestational age and birth weight of the subjects in the present study are similar to that reported from Johannesburg, South Africa [3]. The male preponderance of the asphyxiated babies in our centre is corroborated by other studies [3 , 12]. It is not clear whether this is reflective of the gender distribution of the population or an inherent susceptibility to asphyxia in the male neonate.

Fifteen (33%) of the subjects in the current study had HIE (stages II and III), which was similar to the 32.5% reported by Ekta and Nayan from Pakistan [11], but much less than 77% from Johannesburg and 85% by Shazia and Seema from another Pakistani cohort [3, 13]. The HIE rate in the present study may be an underestimation because only stages II and III were identified. It is possible that some of the infants in stage I were missed as the signs are subtle and easily missed by inexperienced clinicians.

The mortality rate of 31% among asphyxiated babies in this study was in the same range reported from Pakistan and Enugu, Nigeria [11, 12], but much higher than 15% and 13% from Johannesburg and another work in Pakistan respectively [3, 13]. In this study, only patients with Apgar scores of ≤3 at the fifth minute were recruited whereas the Johannesburg and Pakistani groups used scores less than 6 and 7 in the fifth minute respectively to define asphyxia [3, 13]. The subjects enrolled in our study were in the category defined as severe asphyxia in the other studies; the high mortality in the present study may therefore be expected.

Survival of the infant with asphyxia is not just a function of the degree of compromise; it can also be significantly determined by quality of care in terms of cardio-respiratory support and cooling practices. In our centre, none of the babies had invasive ventilation, nitric oxide or brain cooling. Infants with HIE II and III in the Johannesburg study were ventilated; details of the care given in other cohorts were not documented. Mortalities from Persistent pulmonary hypertension of the newborn (PPHN) can be significantly reduced by mechanical ventilation with/without nitric oxide administration.

Skilled resuscitation and appropriate referral of high risk pregnancies and compromised infants are key measures in the reduction of the morbidity and mortality attributable to perinatal asphyxia. Severe HIE (stage III) was found to be significantly associated with mortality in our study with a fatality rate of 73% (HIE II- 25%, HIE I- 17%). The high mortality associated with severe HIE is well documented [14 –16]. The advent of therapeutic hypothermia has led to a drastic reduction in mortality in developed countries [14 –19]. Passive cooling is recommended in settings where the former is not feasible; however this is yet to be actualized in most health facilities in developing countries [20].

Babies born to mothers who did not receive antenatal care were more likely to die in the present study; this was contrary to the Johannesburg findings where antenatal care had no bearing on outcome. They however found the place and mode of delivery to be determinants of outcome. In the present study, while mortality from vaginal delivery (32%) was higher compared to Caesarean delivery (25%), it was not statistically significant. The age of the mothers of the subjects in the present study did not affect the outcome.

3.1 Limitations

The limitations of this study include the retrospective nature, which made standardisation of data difficult. In addition, booking status, details of intrapartum events, resuscitation and postnatal interventions (some of which may have had a bearing on the outcome) were not available for many of the outborn subjects. The study population is too small to make far reaching conclusions. Furthermore, APGAR scores, which was the major tool in the diagnosis of asphyxia in this study is subject to inter-observer variation.

4 Conclusions

The burden of perinatal asphyxia in our centre is high like many others in the developing world. Lack of antenatal care and HIE III were predictive of mortality. Continuous efforts should be made to improve the uptake of antenatal care. Extensive training of relevant health workers in neonatal resuscitation is an important modality towards reducing the scourge.

Conflict of interest

None declared

Funding

None declared

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Perinatal asphyxia in a rural Nigerian hospital: Incidence and determinants of early outcome

Abstract

BACKGROUND:

AIM:

METHOD:

RESULTS:

CONCLUSION:

Keywords

1 Introduction

1.1 Aim

2 Subjects and methods

2.1 Data handling

2.2 Subjects

2.3 Results

Table 1 Demographic characteristics of the subjects Infant characteristics Frequency (%) Gender Male 28 (62) Female 17 (38) Gestational age (wks) <37 7 (15.6) 37–42 32 (71.1) >42 6 (13.3) Birth weight (gm) <2500 4 (8.9) 2500–3999 37 (82.2) ≥4000 4 (8.9)

3.1 Limitations

4 Conclusions

Conflict of interest

Funding

References

Table 1
Demographic characteristics of the subjects

Infant characteristics Frequency (%)

Gender

Male 28 (62)

Female 17 (38)

Gestational age (wks)

<37 7 (15.6)

37–42 32 (71.1)

>42 6 (13.3)

Birth weight (gm)

<2500 4 (8.9)

2500–3999 37 (82.2)

≥4000 4 (8.9)