Respiratory Care of Infants and Children: A Comprehensive Guide
Cold Stress
Cold stress (body temperature <36°C or hypothermia) increases O2 consumption and can cause hypoglycemia, metabolic acidosis, apnea, pulmonary vascular hypertension, and increase right to left shunt. The smaller the infant, the higher the temperature needed to maintain the neutral thermal environment (NTE). The renal system is immature, which makes it difficult to compensate for ventilatory acid-base imbalance. Due to the immaturity of the renal system, the acid-base balance status of the blood can quickly fluctuate. Infants require twice as many calories per kilogram than adults because of their high metabolic rates. Because of their immature immune system, critically ill infants are more susceptible to nosocomial infections.
Nosocomial Infections
Pseudomonas aeruginosa is a gram-negative infection caused by contaminated equipment used in respiratory care.
Oxygen Therapy
The goal of O2 therapy is to provide adequate tissue oxygenation at the lowest inspired FiO2.
Hypoxemia
Definition of hypoxemia in newborns older than 28 days is PaO2 < 60 mmHg, or SpO2 < 90%.
Hyperoxia
The growing lung is more sensitive to oxygen toxicity than the adult lung. Oxygen toxicity may contribute to the development of Bronchopulmonary Dysplasia and retinopathy in premature infants. Increased PaO2 levels in newborns promote constriction of the ductus arteriosus.
Flip-Flop Phenomenon
A larger than expected drop in PaO2 when the FiO2 is lowered. When the FiO2 is increased to the original levels, the PaO2 fails to improve, which is probably due to reactive pulmonary vasoconstriction. Decreasing FiO2 in small 1% to 2% increments can usually prevent flip-flop.
Safe Levels of O2
- FiO2 below 0.50 whenever possible
- PaO2 60 to 80 mmHg or SpO2 88% to 94% to minimize the risk to the infant.
Bronchial Hygiene Therapy
Indicated when accumulated secretions impair pulmonary function and infiltrates are visible on chest radiograph. Complications of bronchial hygiene therapy are rib fractures, subperiosteal hemorrhage, intraventricular hemorrhage, regurgitation, and absorption.
Humidity Therapy
Humidification of inspired gases for infants and children is important. Excessive gas temperature can result in hyperpyrexia and tachycardia. Inadequate gas temperature can result in hypothermia, apnea, acidosis, and stress. Continuous nebulization is avoided in infants and toddlers because of the risk of infection, fluid balance issues, and noise.
Intubation
Endotracheal intubation is a safe method of airway management in infants and children, even when used for extended periods. An inappropriately large endotracheal tube can cause mucosal and laryngeal damage. Complications of ET intubation are tube blockage and esophageal perforation. Because the tongue is large and the epiglottis is high in infants and small children, a Miller straight laryngoscope is best for intubation.
Suctioning
To avoid hypoxemia during tracheobronchial aspiration, infants and children should be pre-oxygenated and ventilated before suctioning. Pre-oxygenation with 100% O2 should be avoided in infants younger than 1 month because of the risk of hyperoxemia and retinopathies. Most clinicians recommend raising FiO2 by 10% to 15% for at least 1 minute before suctioning.
Suction Pressures
- Neonates: -60 to -80 mmHg
- Large infants and children: -80 to -100 mmHg (limited to 5 seconds)
Neonatal Resuscitation
During the protocol of resuscitation of a newborn, if there is no respiratory effort, you will have to give positive pressure ventilation (PPV) for 15-30 seconds.
CPAP
CPAP is indicated when arterial O2 is inadequate despite a high FiO2. This is accompanied by certain signs of respiratory distress.
CPAP in Infants
In infants, CPAP is often needed when the PaO2 is less than 50 mmHg while the infant is breathing an FiO2 of more than 60%, providing the PaCO2 is less than or equal to 50 mmHg and the pH is greater than 7.25. In preterm and term neonates, nasal prongs and nasopharyngeal tubes are used, and in children, a nasal or full-face mask is used. Initial CPAP levels are usually 5 to 6 cm H2O and are adjusted in increments of 1 to 2 cm H2O.
Weaning from CPAP
Weaning from CPAP is considered when:
- O2 is adequate at an FiO2 less than 0.30 to 0.40
- There is a sustained reduction in the work of breathing
- Chest radiograph and clinical assessment indicate resolution of the underlying disorder
The use of CPAP for prolonged periods in preterm infants aids in reducing episodes of apnea of prematurity. Long-term and intermittent use of CPAP is used in children with obstructive airway problems, chronic lung disease, and neuromuscular disorders. There is evidence in preterm and term neonates that using a nasal cannula at a flow of 2 to 8 L/min is as effective and easier to apply than a nasal CPAP system.