When neonatologist Randy Grubbs, MD, first rigged up a model of bubble continuous positive airway pressure to show colleagues at Harris Methodist Fort Worth Hospital in Texas, the initial response to his antiquated-looking system was anything but positive.
Listening as Grubbs extolled the benefits of the bubble CPAP technology he had used during his fellowship, Debbie Crump, RRT-NPS, neonatal supervisor, didn't think much of the idea.
"I was skeptical hearing about this relatively low-tech system and couldn't understand what it had to offer our patients," she admitted. "It wasn't very impressive to look at."
Rather than being offended by the initial response, Grubbs took the feedback in stride. "Bubble CPAP is a simple system without a lot of bells and whistles, and that simplicity makes it look like you're going back 40 years in medicine," he acknowledged. "Sometimes, however, simpler is better."
To get people on board with the idea, Grubbs took a small group of clinicians to the NICU at NewYork-Presbyterian Hospital/Columbia University Medical Center in New York City.
Interacting with clinicians there, Crump experienced a 180-degree change of heart. "That firsthand, hands-on experience convinced me of the value of bubble CPAP," she said. "What a difference it's made for our babies. I can't brag enough about it."
Traditional forms of CPAP are often used in premature infants to keep under-developed lungs open at the end of exhalation while allowing the baby to independently initiate breathing.
The bubble CPAP system delivers medical gases to a blender, through a flow meter, and into a heater/humidifier that conditions the gases to maintain the integrity of the baby's fragile mucous membranes.
The heated and humidified air is delivered to the baby in the isolette via clear corrugated tubing to the nasal prongs and removed from the baby's airway through blue corrugated tubing that is inserted into a bottle of water. The depth of the blue tubing within the bottle of water determines the pressure delivered via CPAP.
"The difference between bubble CPAP and other forms of CPAP is in the way the pressure is delivered," Grubbs said. "With bubble CPAP, the pressure is generated in the outlet tube that's placed into a bottle of water. The depth of the tube within the water determines the amount of pressure delivered. If we want 5 cm of CPAP pressure, we put the tube 5 cm down into the water."
The flow of air out of the tubing sends vibrations to the baby's chest; these recruit more alveoli to increase the baby's functional residual capacity. Because the shaken air molecules move in and out of the lungs more readily, they increase lung inflation and involve more lung tissue in the respiratory efforts.
"You can see, feel and hear the vibrations when you examine the baby, so we'd expect this would help loosen secretions, although that hasn't been demonstrated in the literature," Grubbs said.
The goal of bubble CPAP is to minimize the amount of time tiny babies spend on the ventilator, reducing the risk of chronic lung disease-one of the most common and debilitating outcomes for very low birth-weight premature babies.
"Although infant ventilators have become increasingly sophisticated over the past several years and are certainly necessary in many instances to save babies' lives, they remain one of the major factors associated with developing chronic lung disease," Grubbs explained, "which in turn raises the risk of long-term problems such as higher susceptibility to and severity of respiratory infections and asthma, and neurologic and developmental setbacks."
A Culture Change
The decision to use bubble CPAP at Harris Methodist to provide spontaneously breathing infants with the respiratory support they need came after a year-long analysis of clinical findings.
"We reviewed the medical research literature thoroughly and modeled our process after NewYork-Presbyterian Hospital/Columbia University Medical Center, which reports the lowest rate of chronic lung disease (in premature babies) in the world-6 percent compared to the national average of 24 to 30 percent," Grubbs said.
After the New York trip, an interdisciplinary team started a planning process to introduce bubble CPAP at Harris Methodist. To get started, staff members had to tackle discrepancies in practice patterns.
"We have 16 physicians in our neonatal group, and that means we had 16 different ways of doing things in the past," Grubbs said. "We had to establish agreement on one way to deal with these babies. We now place these babies on bubble CPAP right in the delivery room and then monitor them closely.
"We had to answer key questions, including, 'If the baby is not doing as well as we expect, when are we going to call it a CPAP failure and proceed to intubation and ventilator support?' Once we established those parameters, that consistency received rave reviews from the bedside staff."
Bubble CPAP became a reality in the NICU at Harris Methodist in September 2007. Along with implementing bubble CPAP, the team espoused a change in focus.
"We introduced a very large cultural change, using our clinical skills to determine how a baby is doing and relying a lot less on blood gases, labs and X-rays," Grubbs said. "That took some time, but now people are more attentive to the baby, relying more on their clinical observations and experience rather than on numbers. This change has advanced the care we're able to deliver to these infants."
The combination of bubble CPAP and the culture change has meant a more labor-intensive level of care for these tiny neonates.
"The bubble CPAP system requires a lot more time and attention from the bedside staff, both nurses and respiratory care practitioners," Grubbs said. "Folks at Columbia have been using this technology for 35 years, and they readily acknowledge its success depends completely on the direct care staff."
For RTs, the work begins with careful set-up of the bubble CPAP system.
"The whole secret is getting the right prong size and securing the tubing," Crump said. "You want the prongs real snug in the nares without touching the nasal septum. You might start out with a size 1 prong that fits very snug, and within an hour, you may need to change sizes. We have gone up three sizes on a baby sometimes within several hours. It has to do with the elasticity of the babies' nares."
Clinicians at Harris Methodist follow a special prep procedure to protect the baby's fragile skin while ensuring integrity of the system. "We use a 'mustache' on the upper lip that we make from the rough side of a Velcro strip; the prongs have the softer side of the Velcro to attach to the mustache," Crump said.
"The Velcro really helps secure it. We also place a snug hat on the baby and secure the tubing to that hat withpins and rubber bands. I originally had trouble with that idea, but it's been part of our success with maintaining pressures for the baby."
The bubble CPAP system itself requires monitoring. "We are constantly watching the water level in the bottle and have to remove water often; otherwise, you end up delivering more pressure than you want," Crump cautioned. "Also, if there are no bubbles, you have a leak, the prongs have become too small to keep the seal, or the baby is losing all of the pressure out of his mouth. If that happens, we use a chinstrap to keep their mouths closed. We also suction every three hours, making one pass down each nostril to assure we have airway patency."
The most important part of the treatment plan for babies on bubble CPAP is careful, ongoing assessment and critical thinking.
"You need to look at your baby," Crump emphasized. "We're back to emphasizing all of our clinical skills and critical thinking instead of focusing on the numbers on a ventilator. The bubble CPAP system requires quite a bit of tweaking and is pretty labor intensive for both nurses and RTs, but it keeps us focused on what's important."
Sandy Keefe is a California practitioner. <% footer %>