**2.1 Thermoregulation**

ELBW infants are particularly prone to heat loss immediately after birth due to high body surface area to weight ratio, thin skin, decreased brown fat tissue and decreased glycogen supply. Studies have found significant association of hypothermia to in-hospital mortality, respiratory distress syndrome, necrotizing enterocolitis (NEC), and intraventricular hemorrhage in low birth weight/preterm infants [15, 16]. A retrospective observational study performed at 29 Canadian Neonatal Networks' neonatal intensive care units encompassing 9833 infants born at <33 weeks' gestation showed U-shaped relationship between admission temperatures and adverse neonatal outcomes. Lowest rates of adverse outcomes have been associated with admission temperatures between 36.5 °C and 37.2 °C [15]. Thermal management is crucial for survival of the ELBW infants and includes interventions such as drying, heating under a radiant warmer, placing a hat on the head and plastic film over the body [16, 17]. Frequent monitoring of temperature should be done to avoid iatrogenic hyperthermia, especially when applying multiple interventions simultaneously (e.g. plastic bags + thermal mattresses) [16].

### **2.2 Respiratory distress syndrome**

Respiratory distress syndrome (RDS) caused by surfactant deficiency is an early complication of extreme prematurity. Surfactant deficiency causes decreased pulmonary compliance, alveolar hypotension, and an imbalance between pulmonary ventilation and perfusion [17, 18]. Clinically marked by tachypnea, chest retractions, nasal flaring, cyanosis and grunting, this condition usually progresses to hypoventilation, hypoxemia and respiratory acidosis [17, 18]. RDS was recorded

#### *The Extremely Low Birth Weight Infant DOI: http://dx.doi.org/10.5772/intechopen.96921*

in 80% of babies born at 28 weeks' gestation and in 90% of those born at 24 weeks' gestation according to Vermont Oxford Network data during 2017 [18]. Common complications of RDS comprise air leak syndromes, bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP). Animal and synthetic surfactants have been widely used for the treatment of RDS which resulted with significant reduction in mortality. Also, a shift in practice has been noted towards non-invasive ventilation techniques such as continuous positive airway pressure CPAP [19]. Recent large trials showed a lower risk of chronic lung disease or death from early stabilization on CPAP with selective surfactant administration [20]. However, infants born at 23–24 weeks' gestation, may continue to have high need for intubation during initial stabilization.

The INSURE technique (Intubate-Surfactant-Extubate) for surfactant administration involves giving surfactant through an endotracheal tube while administering positive pressure inhalations, often with premedication. This method has been used since 1994 and efficacy has been replicated in many studies [21, 22]. LISA (Less Invasive Surfactant Administration) on the other hand, is a preferred new method that involves administering surfactant via a small intratracheal catheter, with the baby breathing spontaneously on CPAP or NIPPV support, without sedation [23, 24]. However, a recent study raised concerns over relatively low success rate of the first LISA attempt, often inadequate technical performance quality and recurrent desaturations [24].

Following the increasing use of CPAP, other non-invasive ventilation methods have been subjected to research, mostly nasal intermittent positive pressure ventilation (NiPPV) [25] and high-flow nasal cannula (HFNC). Trials have failed to show difference in rates of death and BPD when NiPPV was compared to CPAP [26, 27]. HFNC has been considered as an alternative non-invasive mode for post-extubating support [28]. Current mechanical ventilation (MV) tactics include shortening of duration of MV and the use of targeted volume ventilation (VT). VT results in shorter ventilation-time, fewer air-leaks and less BPD [17].
