What is the diagnosis for a newborn with severe hypercapnia, decreased oxyhemoglobin (O2) saturation, and reduced tidal volume during sleep?

From the Guidelines

This newborn requires immediate placement on respiratory support, likely continuous positive airway pressure (CPAP) or mechanical ventilation, to address the severe hypercapnia, decreased oxyhemoglobin desaturation, and reduced tidal volume during sleep, as indicated by the American Thoracic Society's clinical policy statement on congenital central hypoventilation syndrome 1. The infant's presentation suggests a possible diagnosis of congenital central hypoventilation syndrome (CCHS), a lifelong disease characterized by impaired respiratory control, particularly during sleep, leading to hypercapnia and hypoxemia 1. Key considerations in managing this newborn include:

• Providing supplemental oxygen to maintain oxygen saturation above 90%
• Implementing continuous cardiorespiratory monitoring
• Conducting a comprehensive evaluation, including chest X-ray, blood gases, and possibly polysomnography to assess breathing patterns during sleep
• Considering caffeine citrate (loading dose 20 mg/kg, maintenance 5-10 mg/kg daily) if apnea of prematurity is suspected The primary goal is to secure the airway and ensure optimal ventilation and oxygenation with artificial ventilation, as CCHS does not resolve spontaneously and requires chronic ventilatory support at home 1. The choice of ventilatory support, such as positive pressure ventilators via tracheostomy, bilevel positive airway pressure, negative pressure ventilators, or diaphragm pacing, depends on the individual case and should be guided by the latest clinical guidelines and expert opinion 1. It is crucial to emphasize that patients with CCHS may suffer complete respiratory arrest or severe hypoventilation at sleep onset, requiring continuous observation and/or monitoring to initiate ventilatory support with each sleep episode 1. Objective measures of oxygenation and ventilation, such as pulse oximeter and PETCO2 monitor, should be used continuously in the home during all sleep time and ideally for hourly/periodic checks during awake time, along with continuous care by a registered nurse trained and experienced in ventilator management 1.

From the Research

Newborn with Severe Hypercapnia

• A newborn with severe hypercapnia, decreased oxyhemoglobin desaturation, and reduced tidal volume during sleep may be experiencing respiratory distress, as seen in ventilated neonates with hypercapnia 2.
• Hypercapnia in ventilated infants can occur even if tidal volume and minute ventilation are maintained, and is often caused by an increase in physiological dead space 2.
• The relationship between dead space and partial pressure of carbon dioxide (PaCO2) has been investigated, and it has been found that PaCO2 is positively correlated with alveolar dead space and physiological dead space 2.

Effects of Hypercapnia on Newborns

• Permissive hypercapnia (PHC) or controlled ventilation is a strategy that minimizes baro/volutrauma by allowing relatively high levels of arterial CO2, provided the arterial pH does not fall below a preset minimal value 3.
• The benefits of PHC are primarily mediated by the reduction of lung stretch that occurs when tidal volumes are minimized, and it can be a deliberate choice to restrict ventilation in order to avoid overdistention 3.
• However, the current concept that PaCO2 levels of 45-55 mmHg in high-risk neonates are "safe" and "well tolerated" is based on limited data, and further prospective trials are needed to study the definition, safety, and efficacy of PHC in ventilated preterm and term neonates 3.

Management of Hypercapnia

• The pathophysiological mechanisms of hypercapnia include the decrease in minute volume, an increase in dead space, or an increase in carbon dioxide production per sec, and it is essential to know the triggers to provide therapy directed at the primary cause and avoid possible complications 4.
• The use of lower tidal volume ventilation was shown to improve survival in mechanically ventilated patients with acute lung injury, but may cause hypercapnic acidosis, and treatment options include optimizing the use of low tidal volume mechanical ventilation to enhance carbon dioxide elimination 5.
• Techniques to reduce dead space ventilation and physiological dead space, use of buffers, airway pressure release ventilation, and prone position ventilation may also be used to manage hypercapnia, and extracorporeal techniques may be used in patients where hypercapnic acidosis cannot be managed with lung protective mechanical ventilation 5.