What is Gentle Ventilation for CDH?

When NICU doctors say they are using gentle ventilation, they mean they are using the lowest possible pressure on the breathing machine to support your baby without damaging their fragile, underdeveloped lungs ^[1][2]. Because babies with congenital diaphragmatic hernia (CDH) have smaller, more delicate lungs, forcing air into them at high pressures can cause tears or long-term damage ^[2]. To keep the pressure safely low, doctors use a strategy called permissive hypercapnia, which simply means they intentionally allow your baby’s blood carbon dioxide (CO2) levels to be higher than what is normally considered perfect ^[3][4].

Why CDH Lungs Need a Gentle Approach

Babies born with CDH have lungs that did not fully grow during pregnancy, a condition called pulmonary hypoplasia ^[5].

In the past, doctors tried to make a baby’s blood oxygen and carbon dioxide levels look perfectly normal on lab tests, often using high pressures on the ventilator to achieve this. However, this approach forced too much air into tiny, stiff lungs, often leading to a complication known as ventilator-induced lung injury (VILI) ^[1][2].

Today, the standard of care prioritizes protecting the lungs over achieving “normal” lab numbers ^[1][6]. Gentle ventilation provides just enough support to keep your baby safe, using small breaths and low pressures to minimize stress on the lung tissue ^[3][4]. During daily rounds, you may hear the medical team discuss keeping your baby’s Peak Inspiratory Pressure (PIP) low—often trying to keep this number below 25—to ensure the ventilator is not pushing too hard ^[1][2].

What is Permissive Hypercapnia?

Permissive hypercapnia goes hand-in-hand with gentle ventilation. When we breathe, we take in oxygen and breathe out carbon dioxide (CO2). If a ventilator is set to a low pressure to protect the lungs, it doesn’t clear out as much CO2 with each breath ^[4].

• Permissive means allowing or tolerating.
• Hypercapnia means higher-than-normal levels of carbon dioxide in the blood.

Therefore, doctors permit the CO2 to rise rather than turning up the ventilator pressure to blow it off ^[3]. A healthy newborn without CDH typically has a CO2 level between 35 and 45 mm Hg. However, according to major medical consensus guidelines, such as the CDH EURO Consortium, it is perfectly safe and recommended for babies with CDH to have a CO2 level between 50 and 70 mm Hg ^[7]. This trade-off significantly lowers the risk of lung damage while the baby’s lungs mature and heal.

What Else Changes With Gentle Ventilation?

Because the goal is to be gentle on the infant’s body, the targets for oxygen and blood tests will look different than those for a healthy newborn. The exact ventilator settings will be customized to your baby’s unique physiology, but standard guidelines often include ^[6][8]:

• Targeted Oxygen Saturation: Instead of aiming for 100% oxygen, guidelines suggest maintaining oxygen levels safely between 80% and 95% in the blood going to the brain (preductal saturation), and above 70% in the lower body (postductal saturation) ^[7]. The preductal oxygen level is usually measured by a glowing pulse oximeter sticker on your baby’s right hand or wrist, while the postductal level is measured by a sticker on their foot. These numbers can be different because high blood pressure in the lungs (pulmonary hypertension) causes some blood to bypass the lungs entirely.
• Choosing the Right Ventilator: Doctors often use conventional mechanical ventilators as their first choice, prioritizing physiological stability ^[1][7]. However, if your baby needs more support, the team may switch to a high-frequency ventilator (like an oscillator or jet ventilator). This is just a different way to be gentle—it uses rapid, tiny vibrations instead of standard breaths to keep the fragile lungs open and protected.

By accepting these adjusted numbers and specialized strategies, the medical team ensures the ventilator works with your baby’s lungs, rather than forcing them to work beyond their current capacity.