Putting baby on ice: a life-saving therapy
MONTREAL - As a 13-month-old toddler, Erika Nordby wandered out of her Edmonton house in the middle of a winter night and fell face down in the snow where she nearly froze to death. Several hours later she was brought back to life with no injury more serious than severe frostbite despite having no pulse when found.
Now the science behind the medical miracle of Erika’s survival is being used to treat babies who have suffered trauma at birth. Even before Erika’s recovery, it was already established that hypothermia protects against brain injury in animals deprived of oxygen. But would it be safe and effective for humans? As Erika was fighting back to health in 2001, British doctors were already experimenting with a new ice therapy. They hoped to stem brain damage in babies who had suffered a lack of oxygen during delivery by lowering their body temperature by four degrees immediately after birth. Naked except for diapers, the babies were chilled for three days on mattresses filled with ice water.
Hypothermia is more complicated than simply putting babies on ice. By the time Erika was found curled up in the snow in temperatures dipping to -20C, her toes had frozen together, she had no pulse and doctors had to restart her frozen heart.
Today, Erika is a healthy 12-year-old. The cold that nearly killed her also saved her life by slowing her body’s metabolism and reducing her brain’s need for fresh, oxygenated blood. Some babies who have been deprived of oxygen during a difficult birth are so ill that nothing will save them. But in moderate to severe cases, it is a way of buying time so the brain can heal on its own. A landmark study published in the New England Journal of Medicine in 2005 found total body cooling reduces the risk of death and disability in infants starved of oxygen.
Accidents like Erika’s have taught doctors how the science of ice can cheat death. Cooling therapy has since become routine care for birth trauma, and some stroke and cardiac patients. But the therapy is still in its infancy. There are many unknowns. What, for example, happens in the brains of such babies? A brain imaging project run out of the Montreal Children’s Hospital is working to find out.
Baby Kavanagh was born at St. Eustache hospital during a planned Caesarean in 2008. The delivery went smoothly but something was wrong with the baby. He was born limp. He wasn’t breathing. Later, doctors discovered the baby had meningitis. The baby needed to be resuscitated. In the controlled chaos that followed, nurses brought the incubator in which the baby was placed so his mother could see him.
At the Children’s neonatal intensive care unit, specialists suggested using an experimental treatment available to infants. They proposed cooling his core body temperature to 33.5 C - several degrees below the normal 37C - for 72 hours.
Therapeutic hypothermia has been shown to almost double the chance of normal survival - 40 per cent of treated babies developed no subsequent problems.
In 2008, the Children’s used the treatment on five babies; in 2009 there were 20; and in 2010 that number doubled to 41. Now nearly every large hospital centre offers hypothermia therapy for birth trauma, or makes arrangements to transfer babies to a facility that does, said neonatologist Nabeel Ali, who developed the Children’s program. St. Justine Hospital began using hypothermia therapy in 2009.
The window of opportunity to start treatment is six hours from the moment a baby is born, and newborns are sometimes flown in by air ambulance.
“I figured we had nothing to lose given the prognosis,” baby Kavanagh's dad said. “He was convulsing, he had bleeding in the lungs, severe asphyxia, cerebral meningitis and (doctors said) he had a 50% chance of survival.” In fact, the very first baby cooled at the Children’s in the fall of 2008 had died, not because of therapy but because he was too ill from the start, Ali explained. Asphyxia occurs in about four in 1,000 full-term babies. Trauma at birth can have many causes including a ruptured placenta, slow fetal heart beat, the umbilical cord is wrapped around the baby’s neck, the newborn’s head is out but its shoulders are stuck, or the infant is born not breathing.
“We’re not good at reversing damage, unfortunately,” Ali said. A portion of brain cells dies in the initial “insult” of oxygen starvation. Then there’s the second stage called “reperfusion injury.” That occurs when the blood supply returns to the brain with fresh oxygen and produces harmful toxins. The newborn’s brain can’t protect itself from chemical reactions such as lactic acid, free radicals and other toxins that continue to damage neurons.
Cold therapy stops this cascade of irreversible injury. Cooling slows the metabolism, lowers the body’s need for energy and gives the newborn time to cope with the toxic byproducts of asphyxia, Ali explained. Until recently, doctors could offer parents of sick newborns little hope for repairing brain damage. Some died. Some later developed hearing and vision problems, cerebral palsy, seizures and cognitive or developmental delays. The results of therapeutic hypothermia are promising - 40 per cent of cooled babies have no long-term consequences. The treatment is only offered in moderate to severe cases of asphyxia because these babies are most likely to benefit, studies show. But while some babies do well, others do not, and researchers at the Children’s are trying to understand what mechanisms underlie these injuries. Other teams in the U.S., for example, are looking at whether variations on existing hypothermia remedies- colder, deeper or longer - would be better.
“Our goal is to figure out why there is a difference and how we can improve the current treatment,” said neonatal neurologist Pia Wintermark, who was recruited from Boston nearly two years ago. Wintermark’s research focus is on profiling brain injury in newborns using advanced neuroimaging techniques. “We can repair damage to the heart and the lungs but not the brain - and that’s frustrating.”
Using MRI to measure blood flow, researchers can now see an injury within the first day of life - what’s normal, what’s abnormal and where exactly this is happening in the brain. “We’re trying to identify as early as possible the baby that might develop brain injury,” Wintermark said, with the idea of developing therapies, for example, medication to improve blood flow, and the outcomes of these newborns.
For her MRI study, Wintermark is also seeking babies who have not been cooled - the control group - to compare their brain images with babies that had been cooled.
Experiments with rats are attempting to alter brain blood flow and somehow staunch cerebral changes or damage. But for now, Wintermark said, the only therapy available for babies who had birth trauma is cooling.
Hypothermia infants cared for at the Children’s are followed until school age, examined by neurologists, occupational therapists and other specialists. They look at how these babies grow, their interactions with their parents and the physical world, and whether they are reaching developmental milestones according to schedule.
Considered the first baby to survive cooling at the Children, baby Kavanagh has since grown into a healthy boy. At 10 months, he stood and walked, faster than his two sisters. By his first birthday, a lung specialist had determined he was fine, and his motor skills have surpassed everyone’s expectations.
Source: Montreal Gazette 03.05.2012
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