What Is CPAP for Newborns and Why Is It Used?

CPAP, or continuous positive airway pressure, is a form of breathing support that delivers a steady stream of pressurized air through a baby’s nose, keeping the lungs gently inflated so the newborn can breathe on their own without a ventilator tube. It is one of the most widely used respiratory interventions in neonatal intensive care, primarily given to premature babies whose lungs are too immature to stay open between breaths. The therapy has been a cornerstone of neonatal medicine for decades, and the evidence behind it has shaped how NICUs around the world manage fragile infants from their very first minutes of life.

How CPAP Keeps a Newborn’s Lungs Working

A premature baby’s lungs are underdeveloped. They lack adequate amounts of surfactant, the slippery substance that lines the air sacs and prevents them from collapsing like a deflated balloon at the end of each breath. Without help, these tiny air sacs (alveoli) stick shut every time the baby exhales, forcing the infant to re-inflate them with each breath. That takes enormous effort for a body that may weigh less than a bag of sugar.

CPAP solves this by maintaining a small amount of positive pressure in the airway throughout the breathing cycle. The pressure keeps alveoli from collapsing at the end of expiration, which improves tidal volume and the amount of air the lungs can hold at rest. It also reduces the effort required to breathe and helps prevent pauses in breathing known as apnea of prematurity.¹ The baby still does the breathing; CPAP simply makes each breath easier by acting as a kind of invisible splint inside the airways.

Which Babies Receive CPAP

The most common reason a newborn ends up on CPAP is respiratory distress syndrome, the breathing difficulty caused by surfactant deficiency in premature lungs. A Cochrane review of five trials involving over 300 preterm infants found that CPAP was linked to roughly half the mortality risk compared with supportive care without CPAP, and it cut the chance of needing mechanical ventilation by about a quarter.² Those numbers underscore why CPAP is now started almost reflexively in many NICUs the moment a premature baby shows signs of labored breathing.

Beyond prematurity, CPAP is used for transient tachypnea of the newborn, a condition in which leftover fluid in the lungs causes rapid breathing, usually in babies born by cesarean section. Researchers have tested early CPAP delivery in these babies to see whether it speeds fluid clearance, though results on that front have been mixed.³ CPAP is also used for apnea of prematurity, the episodes where a premature baby simply stops breathing for several seconds. The continuous pressure helps keep the airway from closing and provides a gentle nudge that reduces the frequency of these alarming pauses.⁴

Types of CPAP Devices

Not all CPAP machines work the same way. The three main types used in NICUs differ in how they generate and regulate the pressure delivered to the baby’s airway, and the choice of device can affect how hard the baby has to work to breathe.

Bubble CPAP

Bubble CPAP is the simplest and cheapest design. The expiratory tubing is submerged in a container of water, and the depth of the tubing sets the pressure level. As the baby exhales, gas bubbles through the water, creating small pressure oscillations. These tiny vibrations may actually help with gas exchange in the lungs, acting as a low-level form of chest physiotherapy.⁵ Engineering studies suggest that the oscillations could improve lung performance by reducing airway resistance at certain frequencies.⁶ In bench testing with a premature infant lung model, the mean airway pressure remained stable during oscillation, and the pressure swings stayed small, suggesting the technique is both effective and gentle.⁷

Variable-Flow and Constant-Flow Devices

Variable-flow CPAP devices use a specially designed nasal piece that redirects exhaled gas away from the baby’s airway, reducing the effort of breathing. In one study comparing the two approaches, variable-flow CPAP lowered the work of breathing by about 13 to 29 percent compared with constant-flow CPAP.⁸ Another trial found that babies on bubble CPAP had higher respiratory rates and more labored, asynchronous breathing compared with those on variable-flow devices, raising the possibility that some infants may do better on one system than the other.⁹

A recent bench study that tested 16 different neonatal CPAP devices confirmed that the mechanism of pressure generation matters. Bubble CPAP, variable-flow, and turbine-driven constant-flow devices all imposed low levels of extra breathing effort, while devices that use mechanical regulation or constant-resistance valves demanded substantially more work from the baby. The highest workload came from a simple T-piece device.¹⁰ In practice, most NICUs have a preferred device, and the choice often depends on cost, local expertise, and the clinical setting.

Masks Versus Prongs

CPAP reaches the baby through a nasal interface, and the two main options are short binasal prongs that sit inside the nostrils and small masks that fit over the nose. A Cochrane review of ten trials involving over a thousand infants found that masks reduced moderate-to-severe nasal injury by about 45 percent compared with prongs. Masks also appeared to lower the risk of CPAP treatment failure, though the evidence was rated low certainty. The choice of interface did not seem to affect mortality, the risk of air leak, or the likelihood of chronic lung disease.¹¹

A separate systematic review looking specifically at strategies to prevent nasal injury found that hydrocolloid dressings, thin protective patches placed on the skin under the interface, significantly reduced the rate of skin breakdown. Simply alternating between masks and prongs, a practice some units use, did not show a clear benefit in the pooled data.¹²

Long-Term Lung Outcomes

One of the biggest fears in neonatal care is bronchopulmonary dysplasia, or BPD, a chronic lung condition that develops in premature babies who need prolonged respiratory support. CPAP, by keeping babies off ventilators and their associated lung damage, has become central to BPD prevention strategies. A quality-improvement study of over 900 preterm infants found that after implementing a structured bubble CPAP program, survival without BPD improved from about 59 percent to 74 percent, and BPD rates dropped from roughly 25 percent to 7 percent.¹³ A separate multi-period study showed a similar trend: as an early bubble CPAP protocol was rolled out and refined, rates of death and severe BPD fell significantly over successive periods.¹⁴

Combining CPAP with newer surfactant delivery methods may push outcomes even further. A meta-analysis published in JAMA compared several noninvasive ventilation strategies and found that a technique known as less invasive surfactant administration (LISA), in which surfactant is given through a thin catheter while the baby stays on CPAP, had lower odds of death or BPD compared with CPAP alone. It also reduced the risk of air leaks.¹⁵

Side Effects and Complications

CPAP is far gentler than a ventilator, but it is not without downsides. The most visible complication is nasal injury. In one incidence study, over 90 percent of newborns on CPAP developed some degree of skin injury around the nose, although most cases were mild. Smaller and more premature babies were at the highest risk of severe injury, and longer time on CPAP increased the odds.¹⁶ Nurses in NICUs spend considerable effort adjusting interfaces, repositioning prongs, and applying barrier dressings to minimize this problem.

Another recognized side effect is abdominal distension, sometimes called “CPAP belly syndrome.” When pressurized air leaks past the throat and into the stomach, the gut fills with gas. In one early study, this occurred in over 80 percent of babies weighing less than about two pounds who were on nasal CPAP, compared with only 14 percent of larger infants. The distension was benign and did not lead to serious bowel problems, but it can alarm parents and temporarily interrupt feeding.¹⁷

Pneumothorax, a leak of air from the lung into the chest cavity, is a more serious concern. A large cohort study across three NICUs found that pneumothorax occurred in about 0.5 percent of all newborns, but the rate was roughly ten times higher in very premature infants. Importantly, the study found that NICU-based bubble CPAP itself was not associated with an increase in pneumothorax; rather, it was delivery-room interventions like initial CPAP at birth and intubation that carried the risk.¹⁸ In near-term and term babies, delivery room CPAP was more clearly linked to pneumothorax, which has led some units to develop protocols to reduce unnecessary early CPAP in babies who may not need it.¹⁹

Does CPAP Affect the Heart

Because CPAP increases pressure inside the chest, a natural question is whether it squeezes the heart and reduces blood flow. Studies in preterm babies have produced reassuring answers, with a caveat. At standard clinical pressures of up to about 7 cm of water, echocardiography showed no significant change in cardiac output, stroke volume, or heart function.²⁰ Even at elevated pressures up to 13 cm of water, one physiological study found cardiac output remained stable.²¹ However, an older study that pushed pressure as high as 10 cm of water did observe a significant drop in cardiac output at those upper levels, especially in low birth weight babies.²² The clinical takeaway is that at the pressures typically used, CPAP does not appear to compromise the circulation, but clinicians watch closely when pressures are raised above the usual range.

How Babies Come Off CPAP

Weaning from CPAP is less straightforward than turning a switch. There are several strategies, and the evidence on which works best is mixed. A systematic review compared gradual pressure reduction (stepping down pressure by 1 cm at a time), sudden discontinuation (simply taking CPAP off when the baby seems ready), and stepping down to lower-support devices like nasal cannula.

Gradual pressure weaning tended to succeed more often on the first attempt, but babies weaned this way came off CPAP about a week later in age. A step-down to nasal cannula achieved weaning about three weeks earlier, but those babies ended up on supplemental oxygen for about eight days longer. Interval training, where CPAP was cycled on and off for set periods, offered no clear benefit. None of the strategies changed the risk of chronic lung disease or the total time spent in the hospital.²³ A randomized trial confirmed that gradual pressure weaning was more successful on the first try than sudden removal, though the total duration of CPAP and hospital stay were similar between the two approaches.²⁴

CPAP Versus High-Flow Nasal Cannula

High-flow nasal cannula (HFNC) is a newer alternative that delivers heated, humidified air through small prongs without the sealed interface that CPAP requires. It is easier to set up, often more comfortable, and causes less nasal injury. A meta-analysis of trials comparing the two found that HFNC produced lower rates of air leaks, nasal trauma, and abdominal distension. Babies on HFNC also reached full enteral feeding sooner.²⁵

The catch is effectiveness. A large trial in nontertiary special care nurseries found that HFNC had about double the treatment failure rate of CPAP: roughly 20 percent versus 10 percent. Rates of mechanical ventilation and adverse events were similar between groups, but the trial could not demonstrate that HFNC was as good as CPAP for initial respiratory support.²⁶ For that reason, most guidelines still position CPAP as the first-line therapy for premature babies with respiratory distress, with HFNC as a reasonable step-down option or a choice for milder cases where the priority is comfort and reduced nasal injury.

CPAP in Low-Resource Settings

Bubble CPAP’s simplicity makes it one of the few high-impact neonatal technologies that works in hospitals with minimal infrastructure. It needs no electricity beyond what powers an oxygen concentrator (or even a compressor), and the underwater seal provides a self-regulating pressure mechanism that does not require sophisticated electronics. In a neonatal ward in Malawi, the introduction of a low-cost bubble CPAP system was associated with survival rates rising from about 44 percent to 71 percent among babies with respiratory distress, roughly tripling the odds of survival.²⁷ That kind of improvement from a single, affordable intervention is rare in global health, and it has driven major efforts to scale up bubble CPAP across sub-Saharan Africa and South Asia.

Transporting Babies on CPAP

When a newborn on CPAP needs to be transferred to a higher-level hospital, keeping respiratory support running during the ambulance or helicopter ride is a logistical challenge. A review of neonatal transfers by one regional transport service found that CPAP was a safe method of respiratory support during land-based ambulance trips for carefully selected infants, with only a small number requiring additional intervention en route.²⁸ Another group developed a transport-specific bubble CPAP protocol and found that after its introduction, fewer babies needed to be intubated for the trip, and those arriving on CPAP had similar rates of intubation in the first 12 hours after reaching the NICU, with no increase in pneumothorax.²⁹ These findings have encouraged more transport teams to keep babies on CPAP rather than defaulting to intubation for the journey.

What Parents Experience

For families, seeing a newborn attached to CPAP equipment is often frightening. The prongs or mask on the baby’s face, the constant bubbling noise (in the case of bubble CPAP), and the tubes and monitoring wires create an image that looks far more alarming than the relatively gentle therapy actually is. A qualitative study of caregivers in Malawi whose infants were on bubble CPAP found that parents felt anxious and fearful, with the main sources of distress being limited ability to hold or interact with their baby and the constraints of visiting hours.³⁰

NICUs that prioritize family-centered care try to mitigate this by encouraging skin-to-skin contact (kangaroo care) even while CPAP is running, explaining the equipment in plain terms, and reassuring parents that their baby is doing most of the breathing independently. Understanding that CPAP is not a ventilator, that the baby is breathing on their own with a bit of extra support, tends to ease the anxiety considerably. Many parents come to view the rhythmic bubbling of a bubble CPAP system as a reassuring soundtrack once they learn what it means.

Why Humidity and Temperature Matter

The air delivered through CPAP needs to be warmed and humidified before it reaches the baby’s airways. Premature infants are especially vulnerable to cold, dry gas because their airway linings are immature and their ability to regulate body temperature is limited. Inadequate humidification can impair surfactant production, slow fluid clearance from the lungs, and trigger inflammation. Cold inspired air can even contribute to hypothermia, which is independently linked to higher rates of complications in very preterm babies.³¹ Heated humidifiers are standard equipment alongside CPAP circuits, and NICU nurses routinely check the temperature and moisture levels in the tubing to ensure the gas reaching the baby is close to body conditions.