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Cooling Therapy Raises Survival in Area Babies With Asphyxia

Monday November 17, 2008
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Nia'Keyia Williams arrived into the world at Ochsner Medical Center, New Orleans, on Oct. 5, but the Cesarean section launch was far from perfect. Nia'Keyia suffered asphyxia due to her mother's premature placental abruption. Fortunately, the skilled team at Ochsner was ready, and Nia'Keyia became the first baby at the hospital to receive therapeutic hypothermia. Now, Nia'Keyia is home with her mom, both are doing well and the baby does not appear to have any neurological deficits to date.

Timing is Everything

Although therapeutic hypothermia is just now making inroads as a treatment for cardiac arrest in adults, its use in perinatal asphyxia has been studied for several years. "It has substantial benefit," says Judy LeFlore, PhD, RNC, NNP, CPNP-PC, CPNP-AC, associate clinical professor and director of the pediatric and acute care pediatric nurse practitioner programs at the University of Texas at Arlington.

These benefits include increased survival and reduced incidence of neurological morbidity from perinatal hypoxic-ischemic encephalopathy. Morbidities include cerebral palsy, blindness, deafness and severe retardation. "More mature babies — greater than 36 weeks — have better outcomes than younger ones," says LeFlore.

A Cochrane review of eight randomized controlled trials found that the use of therapeutic hypothermia in neonates with hypoxic-ischemic encephalopathy resulted in a statistically significant reduction in mortality and neurodevelopment disabilities in survivors. However, more research is needed, particularly to determine benefits after 18 months of age.

Neonatal therapeutic hypothermia must be started within the first six hours so cell death is stopped. "Every cell you save makes a big difference," says Phillip Gordon, MD, PhD, section head of neonatology in the department of pediatrics at Ochsner.

"A neonate's brain has a lot of plasticity," adds LeFlore. "One area of the brain can take on the function of another." In essence, the remaining brain cells may be able to compensate for areas that are damaged.

"The best candidates are those with moderate to moderately severe brain injury," Gordon says. "If it's mild, it will usually correct itself, and if it's too severe, nothing will work." Ochsner has a list of diagnostic criteria that physicians use to determine if a baby is a candidate for cooling.

It's difficult to estimate just how many babies will be candidates for therapeutic hypothermia. However, Gordon treated more than 30 babies over two years at the University of Virginia Health System before moving to Ochsner.

Gordon says another important part of postresuscitation care if the baby is at risk of anuria is a single dose of IV aminophylline administered very slowly. The drug blocks renal adenosine receptors and subsequent anuria caused by DNA lysis and high adenosine levels.

A Close Eye

Ochsner uses the Blanketrol III Hypo-Hyperthermia System, manufactured by Cincinnati Sub-Zero for whole-body cooling. Another common technique is selective cooling with the Olympic "Cool Cap" System, manufactured by Olympic Medical, but Gordon says the blanket is "easier, cheaper, and just as effective." More research is needed to determine which method is best.

Babies on the hypothermia blanket are typically cooled at 33 to 33.5 degrees Celsius for 72 hours. Nursing care includes frequent turning to prevent skin breakdown and monitoring temperature, vital signs, and cardiac rhythm, says Shelley Thibeau, MSN, RNC, clinical coordinator for Ochsner's Neonatal ICU. Other areas to monitor are electrolytes, liver function, complete blood count, bleeding measures (i.e., PT, PTT) and blood gases, says LeFlore.

"You also need to monitor the baby's comfort level," says Thibeau. "You can only use a thin blanket between the hypothermia blanket and the infant, so we used blankets under the hypothermia blanket to create a nest for Nia'Keyia." Other comfort measures included gentle touch and a pacifier.

Shivering is uncommon but may occur, particularly when the temperature is first lowered. A bigger flux in temperature causes more shivering, which is usually not treated. "It's hard to watch kids shiver," says Gordon, "but better that than to have them have special needs from neurological problems." Even for postresuscitation babies who aren't being cooled, the temperature should be kept normal to low normal. "Overheating is the worst possible scenario with brain damage," he says. "Even a little overheating can damage brain cells."

At the end of 72 hours, the baby is rewarmed by 0.2 degree C every 30 minutes until the temperature is 36 degrees C rectally. During rewarming, the baby's temperature should increase no more than 0.5 degree per hour.

Be Prepared

Thibeau took the lead in preparing nurses for the first neonatal therapeutic hypothermia. She adapted a clinical practice guideline from the University of Virginia Health System where Gordon previously practiced. Education was the next step. "We set up a learning station for several months so nurses could learn how to use the equipment," she says. The self-instruction station included the cooling equipment and a booklet that was useful not only for learning, but for a resource when Nia'Keyia arrived on the scene. "Of course, it was a weekend," notes Thibeau wryly.

With a busy 36-bed ICU, the challenge was to ensure every nurse visited the station. Attendance was encouraged at staff meetings and through newsletters and clinical updates.

More to Come

Nurses in the Ochsner NICU are looking forward to treating more infants who meet the criteria for therapeutic hypothermia. "It's an exciting program," Thibeau says. "For a select group of infants, it has very nice results."


Cynthia Saver, RN, MS, is a freelance writer.To comment on this article e-mail editorSC@nurseweek.com.