A study to determine the factors influencing the respiratory support in very low birth weight babies in a tertiary care hospital

 

 

Abstract               Background: Improved use of antenatal steroids, labour room CPAP, trial of CPAP before intubation and caffeine have changed the way a preterm baby with RDS is managed in the last decade¹. Many babies with RDS who used to receive prophylactic or early rescue surfactant are now managed with CPAP alone, others are administered surfactant only if they fail CPAP.^2,3 But, in this process of trial of CPAP, a few babies receive surfactant as “late rescue” after few hours of trial of CPAP. Objective: To evaluate factors determining long duration of respiratory support (CPAP / ventilation > 120 hours) in VLBW babies in Indian NICU. Methodology: A prospective longitudinal study was conducted at gadag institute of Medical Sciences, gadag from January 2018 to December 2018. All legally viable preterm babies < 32 weeks and < 1500 grams (inborn or out born admitted within 2 hours of birth) were included in the study. A total of 45 Babies were included in the study. Results: Out of 45 babies 4 babies were excluded from analysis due to major malformation in 3 and referral of one case. A definite association was noted between gestation (86 % of <28 weeks, 46 % of 29-30, 18 % of 31-32 weeks babies, p=0.02) and long duration of respiratory support. Boys vs girls (61 % vs 32%, p=0.06), babies born after spontaneous labor vs delivery for maternal / fetal reasons (67 % vs 32%, P0.06) were likely to require long duration of respiratory support. Conclusion: 50 % babies of very preterm babies required no / minimum respiratory support of <24 hours. Babies needing intubation before trial of CPAP, boys, preterm labor and with hsPDA are associated with long duration respiratory support.

Key Word: low birth weight.

 

 

INTRODUCTION

Improved use of antenatal steroids, labour room CPAP, trial of CPAP before intubation and caffeine have changed the way a preterm baby with RDS is managed in the last decade¹. Many babies with RDS who used to receive prophylactic or early rescue surfactant are now managed with CPAP alone, others are administered surfactant only if they fail CPAP.^2,3 But, in this process of trial of CPAP, a few babies receive surfactant as “late rescue” after few hours of trial of CPAP. Previous studies have addressed the tiniest of babies who are at high risk of CLD and hence, not intubating is critical. In India we manage mostly babies > 28 weeks and > 1000 grams. Hence, the incidence of CLD isn’t high. Studies from India⁴ have shown that surfactant followed by CPAP may be a better approach than CPAP trial followed by late surfactant. Interventions to prevent RDS should begin before birth and involve both paediatricians and obstetricians as part of the perinatal team. Often there is prior warning of impending preterm delivery, allowing time for interventions to be considered including in utero (maternal) transfer where appropriate. Ultrasound examination of cervical length and testing for the presence of fetal fibronectin in vaginal secretions can help to predict the risk of preterm birth⁵. Preterm babies at risk of RDS should be born in centres where appropriate skills are available for stabilization and ongoing respiratory support, including intubation and mechanical ventilation (MV) if indicated. Long-term health outcomes for extremely preterm babies are better if they receive their initial neonatal care in tertiary units. It is possible that some of the babies who are given surfactant late, after a trial of CPAP have milder RDS and this approach is appropriate. On the contrary, it is biological sense that denial / delaying surfactant, may be prolonging the naturally history of RDS. In this analytic study, we evaluate the determinants of “duration of ventilation” in VLBW babies in an Indian tertiary NICU, with primary interest in timing of surfactant. Although death / CLD is an ideal patient relevant outcome, longer hours (>120 hours in our study) are associated with risks of infection, mandate cost intensive device and skilled manpower use; and is an important outcome in a country like India where most of health care is not state sponsored, and family pays.

 

OBJECTIVES

To evaluate factors determining long duration of respiratory support (CPAP / ventilation > 120 hours) in VLBW babies in Indian NICU.

 

METHODOLOGY

A longitudinal prospective study was done in Gadag institute of Medical Sciences from January2018 to December 2018. All legally viable preterm babies < 32 weeks and < 1500 grams which were delivered in the same hospital or referred from other hospital or admitted in the NICU of the Hospital within two hours of delivery who required surfactant administration were included in the study.

Inclusion criteria: All legally viable preterm babies < 32 weeks and < 1500 grams (inborn or out born admitted within 2 hours of birth).

Exclusion criteria

1. Babies with associated surgical illnes
2. babies < 24 weeks gestation and < 400 grams birth weight)

All legally viable babies (>23 weeks and >400 grams) are offered optimal resuscitation and NICU care, we do not withhold ventilation or surfactant, if clinically indicated. Most of the preterm births are a planned activity, the obstetrician and neonatology team prepare for optimal care of a VLBW baby. Eligible babies included in the study were treated for respiratory distress according to unit’s standardized respiratory care policy. Data was collected prospectively for survival, duration of CPAP / ventilation, and all the determinants like gestation, weight, sex, antenatal steroids (ANS), cause for preterm birth (spontaneous preterm labor or planned delivery for maternal / fetal indication), ventilator associated pneumonia (VAP) and patent ductus arteriosus (PDA).

Surfactant policy

1. We do not administer prophylactic surfactant (in labor room, before onset of respiratory distress)
2. If a preterm baby (<32 weeks / <1500 grams) baby requires intubation (for resuscitation / severe apnea), surfactant is administered.
3. Surfactant is administered if a preterm baby has persistent respiratory distress in spite of PEEP of 6 or requires an Fio2 of > 30% after a trial of effective CPAP (for 1-2 hours after stabilization). This decision is taken by the treating team of residents and consultant. Data was entered in excel sheet and analyzed using SPSS v 20 and analyzed.

RESULTS

In our study a total of 45 eligible babies were enrolled during the study period. out of the 45 cases 4 cases were excluded (3 due to major malformation and 1 was referred to another hospital). Hence a total of 41 babies were enrolled for the study.

Table 1: Baseline characteristics of the study subjects

\The mean gestational age of the babies in the study group was 29.6 +1.8 weeks in our study, with majority of them (83%) had crossed 28 weeks of gestation. Nearly 41.5% of the babies weighed between 1001-1250 gms, 31.7 % weighed more than 1250 gms. The mean birth weight of babies in our study was 1150+ 217 gms. Boys constituted nearly 58.5% of the study population. Nearly 95.1% present with intramural and 82.9% of the babies were delivered by LSCS.

Table 2: Clinical features of the new born

16 babies (39 %) had risk of EONS, were delivered premature due to preterm labor / rupture of membranes, others for maternal or fetal indications. 26 (63.4%) babies received a complete course of ANS, and 14 one dose (34.1%). We have very high compliance to ANS for anticipated preterm birth. Intubation was done in 43.9% of the babies for the purpose of resuscitation.18 (44%) babies received LR CPAP. 17 (41.5%) babies received Early rescue surfactant (within 2 hours) and 6 (14.6%) babies received surfactant later. Nearly 53.6 % of the babies had Co2 of more than 30 always. the oxygen saturation of more than 89-95 % for more than 6 hours was seen in nearly 12.2 % of the individuals. 19.5% of the babies had CRP positive for the culture proven sepsis and nearly 24.4% of the babies received Antibiotics for more than 5 days.

 

Table 3: Respiratory Support Required

Type of support	Number(%)
Respiratory care in labor room
LR CPAP	18(44%)
Intubation in Labour room	9(22%)
Need for respiratory support in NICU
No need of respiratory support	10(24%)
<24 hrs Intubation / CPAP	14(34%)
Need for >120 hrs respiratory support	12(29%)

 

 

 

 

 

 

 

 

18 (44%) babies received LR CPAP, 9 (22%) babies required intubation in LR. 10 babies (24 %) required no respiratory support. Half the babies required brief respiratory support - 6 (14%) babies were managed on CPAP alone, 14 (34%) babies required less than 24 hours of intubation. 17 babies received Early rescue surfactant (within 2 hours) and 6 babies received surfactant later. 2 babies died, 3 babies developed CLD (12% death/CLD). 12 (29%) babies required more than long duration (ventilation / CPAP > 120 hours) of respiratory support.

Table 4: Factors determining need for Long Respiratory Support

 

A definite association was noted between gestation (86 % of <28 weeks, 46 % of 29-30, 18 % of 31-32 weeks babies, p=0.02) and long duration of respiratory support. Boys vs girls (61 % vs 32%, p=0.06), babies born after spontaneous labor vs delivery for maternal / fetal reasons (67 % vs 32%, P0.06 ) were likely to require long duration of respiratory support. Babies requiring intubation before trial of CPAP (60 % vs 18 %, p=0.03) required long duration respiratory support. This may merely be a reflection that these babies had a more severe RDS to begin with. Support / coin trials where babies were randomized trials, to early intubation or CPAP trail before intubation. Our respiratory care policy was to try CPAP if babies were not intubated in LR for resuscitation or for severe apnea. Babies with hsPDA (86 % vs 33 %, p=0.02) (7 babies were treated for ECHO proven hsPDA). In our unit, ECHO was performed only when PDA was suspected clinically based on poor perfusion or unresolving RDS. ECHO was performed by pediatric cardiologist, we do not do clinician performed ECHO for all these very preterm babies. Hence, this association may also be biased. We found no increase in death / CLD or duration of respiratory support in babies who received surfactant late, after a trial of CPAP. Following factors had no association with long duration of respiratory support in our study - birth weight of baby, doses of antenatal steroids, mode of delivery, timing of surfactant, risk of EONS or VAP. 8 babies had CRP / culture positive sepsis, in 10 babies possibility of infection couldn’t be excluded as antibiotics were continued / upgraded as more respiratory support was required, although infection markers were absent.

DISCUSSION

A total of 41 babies with pre maturity were analyses in our study. Increasing numbers of very preterm and VLBW infants are surviving because of advances in both perinatal and neonatal care over the past two decades⁶. The mean age of gestation in our study was 29.6 weeks among the premature mothers and mean birth weight was 1150 gms. The findings of our study was similar to the study findings of Daynia E Ballot et al⁷ where age of gestation was 29.9 weeks of pregnancy with mean birth weight of 1133.5 gms . In the study done by DenizAtalay et al⁸ the preferred mode of delivery followed was LSCS for 89.7% of the subjects which is similar to our study findings. In many cases, obstetrician-gynecologists teamed with neonatologists and contributed to saving ELBW infants, by delivering them via CS, thereby favorably influencing the outcome for the newborn⁹. Minguez-Milio et al¹⁰ reported that delivery mode did not affect survival; however, delivery via CS was associated with lower morbidity and better prognosis for neurodevelopmental long-term outcome in ELBW infants. Nearly 52 % of the study participants required resuscitation soon after birth in our study which is also similar to the study fidnings of DenizAtalay et al⁸. The sepsis was seen in nearly 19.15 of the babies in our study where in Deniz study⁸ sepsis was seen in nearly 80% of the babies. CPAP can be delivered via a face mask or a shortened endotracheal tube taped into the nasopharynx¹¹. T-piece devices enable a controlled delivery of a set background CPAP with a measured peak inspiratory pressure. If lung inflation is needed a single sustained inflation of about 25 cm H 2 O for about 15 s may be better than repeated manual inflations, although more research is needed for this intervention¹². Self-inflating bags do not require a pressurized gas supply to deliver air flow but cannot deliver CPAP, and the peak inspiratory pressure cannot be controlled beyond the use of the safety valve, which is usually set at about 40 cm H 2 O. Flow-inflating bags cannot deliver accurate CPAP and even in experienced hands produce variable gas volumes during lung inflation. MV can be avoided by using the ‘INSURE’ (INtubate – SURfactant – Extubate to CPAP) technique and this method has beenshown in randomized trials to reduce the need for MV and subsequent bronchopulmonary dysplasia (BPD)^13,14. Following surfactant administration there may, after a variable period of time, be a need for a further dose of surfactant. In randomized trials 2 doses are better than a single dose¹⁵ and a study with poractantalfa showed that up to 3 doses compared to a single dose reduced mortality (13 vs. 21%) and pulmonary air leaks (9 vs. 18%)¹⁶. It is practical to use a flexible dosing schedule basing the time of repeat doses on the baby’s clinical condition and oxygen requirements and there are pharmacokinetic data to support this approach¹⁷ Although clear evidence of long-term benefit is still lacking¹⁸, tolerating higher PaCO 2 levels can lead to reduced time on MV and is now accepted practice¹⁹. Implementation of a ventilation weaning protocol allowing a degree of hypercarbia can result in earlier extubation and overall reduction in the duration of MV²⁰. Several authors have reported low gestation to be a risk factor for poor responsiveness^21-23, while gender has not been reported by any. However, it has been shown that neonatal mortality, short-term morbidity and adverse neurodevelopmental outcomes are higher among male than female infants²⁴. In our study, PDA incidence was 86 % which is much higher when compared to the study findings of Deniz et al.⁸

 

CONCLUSION

50 % babies of very preterm babies required no / minimum respiratory support of <24 hours Babies needing intubation before trial of CPAP, boys, preterm labor and with hsPDA are associated with long duration respiratory support.

 

REFERENCES