Neobook — clinical reference

Hypoxia, hyperoxia, target oxygen saturation monitoring

Hypoxia and hyperoxia are associated with increased morbidity and mortality in neonates. Based on research, the recommended target oxygen saturation for neonates on oxygen therapy is 90–94%. A patient on room air target oxygen saturation is ≥90%. While hypoxia is associated with high mortality rates, oxygen saturation above target level (hyperoxia) on patients on oxygen therapy is associated with increased risk of retinopathy of prematurity, chronic lung disease and preterm brain injury. Hence active weaning of oxygen therapy according to target oxygen saturation is of great importance.

Consider persistent hypertension of the newborn if there is differential oxygen saturation. This is defined as a difference of >10% of right hand oxygen saturation and foot oxygen saturation. This is commonly seen in patients with meconium aspiration syndrome.

Consider congenital cyanotic condition in patients with low oxygen saturation on 100% FIO₂ who are not in respiratory distress.

Methods for delivering oxygen

Nasal prong oxygen

Nasal prong oxygen should ideally be administered via an oxygen blender and humidified. This allows one to adjust the fraction of inspired oxygen (concentration of oxygen in gas mixture of oxygen and medical air, FIO₂). The concentration of oxygen in room air is 21%.

Indications for nasal prong oxygen therapy include all neonates with oxygen saturation <90% and or with features of mild respiratory distress on room air. Term neonates admitted for observation in 16B on nasal prong oxygen should be actively weaned off oxygen over 4 hours. Those babies failing to wean off oxygen during that time or develop features of worsening respiratory distress warrant admission. Babies needing FIO₂ ≥30% within 1 hour of life or who clinically deteriorate with features of respiratory distress may need NCPAP. All these patients are to be discussed with the registrar/consultant as other important information will determine candidacy for NCPAP e.g. life-threatening congenital abnormalities, NCPAP availability, etc. All neonates admitted to 16B on nasal prong oxygen should get a CXR, admission bloods, be started on antibiotics and should be reviewed later.

Babies who were previously on room air and change condition (develop signs of respiratory distress/apnoeas) or now require nasal prong oxygen should be worked up for possible nosocomial pneumonia. They should get a CXR, a septic workup and be started on second line antibiotics. They should be reassessed and put on the red flag list to monitor for signs of deterioration, follow-up septic workup results and have their CXR reviewed.

Nasal CPAP (continuous positive airway pressure)

CPAP involves delivering gas, ideally heated and humidified, with a measurable and controllable pressure which is transmitted using an interface such as short soft nasal prongs or mask, connected tightly to the baby's face creating a seal. It delivers positive end-expiratory pressure and maintains a set pressure throughout the breathing cycle. The benefits of CPAP include improving pulmonary mechanics by increasing functional residual capacity; improves pulmonary compliance and work of breathing; splinting the upper airway, maintaining lung expansion prevents alveolar collapse; reduce obstructive or mixed apnoea and improves gaseous exchange by increasing partial pressure of oxygen, reduces intrapulmonary shunting.

Indications for nasal CPAP include

Babies >750g in moderate respiratory distress needing FIO₂ ≥30% maintain oxygen saturation >90%. These patients should ideally be admitted to high care or NICU.
Babies weighing 700g–749g are offered NCPAP if in moderate respiratory distress and oxygen requirement exceeding 30%, however, this is administered in 16B and not NICU or high care.

Nasal CPAP is usually started at a pressure of 5 cm H₂O, flow of 5L/min and fraction of inhaled oxygen (FiO₂) of 30%. Following this, the CPAP is titrated to reduce the work of breathing, flow and FiO2 to achieve the saturation targets (90%–94% for preterm neonates). Correct placement of the CPAP mask and harness is necessary to prevent pressure sores. One should also ensure the humidifier is on and water is filled to the required level to prevent nasal mucosal injury. Always review patients on CPAP to ensure there is no deterioration in condition e.g., worsening respiratory distress, apnoea, increased FIO₂ requirements. Active weaning of FIO₂ to achieve target oxygen saturation level should be done to prevent complications of hyperoxia. Complications of NCPAP include trauma (related to mask and harness), air leak syndrome (e.g. pneumothorax, pneumomediastinum) and gas insufflation and abdominal distension.

Bi-level CPAP, Duo-PAP, or BIPAP

BIPAP: These are variants between CPAP and IPPV that use low pressure differences between inspiratory and expiratory phases at PIPs of 9–11cm H₂O at rates of around 20–30 per minute with inspiratory times of up to 1.0. The benefits include increasing alveolar recruitment, increased functional residual capacity, and decreased work of breathing. One can start with a low PEEP of 5. The high and low pressure difference of 3–4cm H₂O, inspiratory time 0.5–1.0 and rates 10–30/min.

Duo-PAP: The parameters for the Duo-PAP machine are PEEP 5 (starting)-8cm H₂O (maximum),PDuo 8 (starting)-15 (maximum),rate 20–30bpm and inspiratory time 0.5-1.0 sec.

Invasive mechanical ventilation: (neonates with a birthweight >900 g)

prolonged or recurrent apnoea
hypoxia (PaO₂ <50mmHg or oxygen Sats <90%) despite FIO₂ >0.6
PaCO₂ > 60mmHg with acidosis pH <7.25
Relief of increased “work of breathing” in an ill neonate

Surfactant therapy

Surfactant is used predominantly in preterm infants with respiratory distress syndrome due to developmental surfactant deficiency. There are conditions where surfactant is inactivated e.g. infants born to diabetic mothers, meconium aspiration syndrome and pulmonary haemorrhage.

Indications for surfactant therapy include neonates with respiratory distress syndrome on NCPAP for 1 hour with oxygen requirements of ≥30% FIO₂ or with features of worsening respiratory distress. To discuss all cases with the registrar on call.

The unit used the bovine sourced surfactant named “Survanta”. The dose for Survanta is 4ml/kg. The minimally invasive surfactant therapy (MIST technique) is the preferred method of delivery which is associated with better outcomes than using an endotracheal tube. The complications of surfactant include; transient increased oxygen requirements post-procedure, pharyngeal administration, surfactant given to one lung, pneumothorax and pulmonary haemorrhage. If the neonate shows signs of worsening respiratory distress to immediately check all vital signs, order a CXR and notify your senior.
A repeat dose of surfactant can be administered 6 hours after the administration of the 1st dose if the oxygen requirement remains ≥ 30% or worsening respiratory distress. Always order a CXR prior to administration of 2^nd dose of surfactant.

Rahima Moosa Mother and Child Hospital - Neonatal Care Handbook 2023; Oxygen therapy; Hypoxia, hyperoxia and target oxygen saturation monitoring, Methods of oxygen delivery
Last checked for updates: January 2024