Respiratory distress in Full and Post term neonates: Prevalence, Etiologies and Outcomes in a Tertiary Health Center in Yaoundé

Introduction Respiratory distress (RD) is a common condition for admission of newborns in neonatal care unit (NCU), in both preterm and full-term neonates. Our objective was to describe the clinical features, causes and treatment of RD in full term neonates in a tertiary health center in Yaoundé, the Essos Hospital Centre (EHC). Patients and Method We conducted a cross sectional retrospective study. Full term neonates with RD at EHC from January 2017 to December 2018 were included, assuming clinical signs of RD prior to 48 hours following admission. Factors evaluated: incidence of RD, main etiologies, short term outcomes and risk factors for severity. Data were collected using a chart, then analyzed using software Stata Version 13. Results 186 full term neonates out of 2312 newborn babies admitted in NCU, met the inclusion criteria giving a prevalence rate of RD of 8%. Sex ratio of 2.15 was favoring males; median age at admission was 7.25 hours and 89.2 % were born at a median gestational age of 38 weeks. Clinical signs of RD were dominated by signs of respiratory control with a Silverman score above 4/10 in 64%. The most common etiologies were neonatal infection / pneumonia (45.9%), followed by transient tachypnea. Clinical management was performed using nasal cannula oxygen and antibiotics. Perinatal asphyxia, cyanosis and caesarian section were found to be associated with severe RD in this setting. Mortality rate was 10.4%. full in this setting, with neonatal infection as preeminent etiology; the mortality rate is high and the management still inappropriate.


Introduction
Respiratory distress is a common condition in neonates requiring admission in a neonatal care unit (NCU) [1]. It can occur in both preterm and full-term neonates affecting both morbidity and mortality rates [2,3]. The main medical diagnoses that are related to these conditions are transient tachypnea, meconium inhalation syndrome, respiratory distress syndrome also known as hyaline membrane disease and pneumonia [4]. Due to increasing meconium inhalation, respiratory distress syndrome, although seen primarily in preterm babies, is also seen increased in full-term neonates and deserves more attention [5].
Sparse data of surgical causes of RD in sub-Saharan Africa may be due to shortage in antenatal diagnosis, including limited performance of routine third trimester echographies during pregnancy plus low capacity of clinical diagnosis in the labor room. Consequently, many RD cases are medical pulmonary diseases and/or due to congenital cardiovascular conditions [4]. In recent years, the widely used antenatal corticosteroids have resulted in a reduction of hyaline disease especially in preterm babies. However, in parallel the increasing rate of caesarian section has led to more recorded cases of RD in full-term neonates [6]. In Cameroon, the General Hospital-Douala team, JN Tochie et al in 2016, reported that RD represented the main cause of neonatal admission (47.5%) in the NCU [7]. Elsewhere, in Nepal, RD contributed a third of NCU admissions, an incidence of around 4% [8]. Overall, data remain scarce in low resource settings especially for full term neonates with an incidence rate recorded between 1.2 to 7.2% in term live births. In addition, RD morbidity in low resource settings seems to be greater compared to data of high-income countries [9]. As epidemiological trends show an increasing rate of RD in full-term newborns [10,11] we designed this study with the primary objective to assess and describe clinical aspects, causes and management of RD in full and post-term neonates in a tertiary facility in Yaoundé.

Method
Type, site, duration and population We conducted a cross sectional retrospective study over a 24 month-period at Essos Hospital Centre.
Neonates ≥ 37 weeks, aged less than 28 days were included, assuming admission in NCU for RD during the rst 48 hours of life.

Data collection
Files of neonates eligible were extracted from the neonatal inpatient registry. Data collection lasted for 6 months from January to June 2019. For each newborn, the following variables were recorded: maternal sociodemographic characteristics, clinical features, treatment and early outcomes. Clinical assessment of severity was based on Silverman score quotation. In this study RD was de ned as the presence of abnormalities of F (frequency of breathing), T( V(ventilation), O( oxygenation). RD with Silverman score above 4 was considered severe. The criteria listed below were retained for the main diagnosis. To investigate the RD in this NCU, le analysis included: clinical assessment = rate of breathing, cyanosis, and Silverman score and pulse oximetry. Other investigations recorded were full blood count, C-reactive protein, and chest radiography as soon as the baby was transportable. The key conditions retained for diagnosis in our study based on clinical and chest x-ray were : transient tachypnea (rapid onset of RD after birth with super cial tachypnea with favorable outcomes within 24 to 48 hours), meconium aspiration syndrome (established in case of RD in full or post-term newborns with a story of perinatal asphyxia and meconium stained amniotic uid), congenital pneumonia (in the presence of isolated RD or associated with any feature of neonatal sepsis), respiratory distress syndrome (de ned as onset of RD before 24 hours of life without honey moon period with lung (thorax) retraction, pulmonary hypertension in case of RD with critical cyanosis with no criteria for infection, congenital heart disease( in case of RD plus heart murmur or abnormalities at echocardiography); surgical conditions were suspected in presence of asymmetry at clinical auscultation and/or clinical improvement at crying plus results of medical imaging. Each diagnosis suspected was con rmed by a senior pediatrician in the medical le of the patient after viewing of the chest x-ray and/or cardiac echography done following admission.

Data analysis
After collection, data were transfered in software Cs pro version 7.1 then analyzed using software Stata

Clinical characteristics and main etiologies
Amongst the neonates included, almost 9 of 10 had an Apgar score below 7 at 5mn of life and 2 of 3 ( 64%) had a Silverman score quoted above 4 on admission. Clinical cyanosis was present in 54%, with normal pulse oximetry above 94% for 8.1% (table 2). The main etiologies of RD in this setting were pneumonia (44%), followed by transient tachypnea (35.4%) and meconium aspiration syndrome (16.6%).
Surgical causes were few, representing 1.6% of cases. (See table 3) Management, outcomes and associated factors Nasal oxygen was widely provided to the neonates with antibiotics as adjunct using 2 drugs given by intravenous infusion. Supportive treatment included parenteral perfusion on the rst day of treatment while the baby was put on an oral diet. In this setting, the mortality rate was 10.2%. Not surprisingly, being cyanotic increased the risk of severe RD (OR=6.509; P=0.000); having an Apgar score below 7/10 at 5 mn increased the risk of severe RD 9 fold (OR=9.412, P=0.005). Lastly, neonates born by C-section had a lower risk of severe RD than those born vaginally (OR=0.412; P=0.050), as shown in table 4.

Discussion
This study could be a pioneering one in analyzing the pro le of RD in neonates born after 37 weeks of gestation in Cameroon. As rst nding, our rate of RD admissions in NCU of 8% was slightly higher than the global record, around 5 to 7% of term live births including data observed in Saudi Arabia and Baghdad in a tertiary level NCU of 1.64% -2.78% [12,13]; these discrepancies can be explained by exclusion of post term neonates and/or inclusion in neonatal units versus maternities. On the other hand, our prevalence rate was lower than those recorded in Egypt and Karachi [3,14], where neonates were included irrespective of gestational age. Of note, we found a preeminence of RD in males in our setting. This nding was consistent with two studies showing susceptibility of the male gender for RD without any clear explanation [14,15]. With regards to the causes, pneumonia stood as the rst cause of RD of in this setting thus con rming previous data; this is easily understandable as neonatal infection is a leading cause of morbidities and mortality in our environment [16]. In second position, transient tachypnea was posting a rate concordant with the level of practice of caesarian sections (31.7%) in this population, though the speci c rate of elective caesarian sections was not known. Of note, this preeminent TT among this population also t with the 10% of mothers having a history of maternal diabetes and/or foetal macrosomia [17][18][19]. Following TT, meconium aspiration syndrome(MAS), was the third cause of RD; unfortunately this diagnosis of MAS can lead to respiratory distress syndrome in fullterm neonates and be challenging to manage in absence of exogen surfactant and bubble CPAP [20,21]. We can attest than other causes of RD (diaphragmatic hernia, oesophageal atresia,choanal atresia) were relatively scarce. This scarcity can be attributed to the delay in diagnosis and/or limited access to diagnosis. Regardless of the very limited means available for optimal management of infants in RD (oxygen and antibiotics), notably the lack of positive expiratory pressure known to be helpful in many cases of RD, the mortality rate observed around 10% was quite laudable in our context [22,23].
Looking at the associated factors of severity, a surprising nding in this study was the protection conferred by Caesarian sections, but we can explain this by the fact that many C sections were done emergently, reducing the risk of perinatal asphyxia and therefore protective for the newborn.
In conclusion, RD in neonates born after 37 weeks gestation is mainly due to neonatal infection and pneumonia ; the outcome is still critical with 10.4% mortality rate due to lack of optimal management thus supporting extended access to positive expiratory pressure devices.