Your Pregnancy Matters
Total body cooling: Saving babies' lives after emergency delivery
July 23, 2019
On the Your Pregnancy Matters blog, we talk about a lot of fun topics, like gender reveal parties and head-to-toe ultrasound tours. However, as your pregnancy resource, it’s important to touch on situations that can be scary, such as labor and delivery complications and how we support women and babies during these times.
One of the most common concerns our pregnant patients have about childbirth is that something might go wrong during labor, resulting in their baby having brain damage. While such emergencies are infrequent, one of the advantages of giving birth at a comprehensive facility like ours is that our patients have access to a state-of-the-art treatment that can serve to reduce the potentially devastating effects of hypoxic ischemic encephalopathy(HIE), or infant brain damage.
In the rare event an emergency occurs, our neonatal intensive care unit (NICU) offers total body cooling for newborns – the only therapy currently shown to reduce brain damage if started in the first six hours of life. The therapy can have dramatic effects on long-term outcomes for infants, reducing death and certain disabilities by more than 10%.
What is total body cooling?
Total body cooling (or whole-body hypothermia) is a process where the baby’s temperature is carefully lowered after a traumatic labor experience. Essentially, we’re protecting the brain by minimizing the production of toxic substances that can cause brain injury.
When the brain does not have enough oxygen or energy to function, it produces toxic chemicals which can ultimately damage a baby’s brain. When oxygen is restored to the brain, there is a time period where the brain attempts to recover from the injury. Unfortunately, a second wave of toxic chemicals is often released, which can further injure the brain.
Because of this, the majority of brain damage can occur during and after restoration of blood flow and oxygen to the brain – not necessarily during birth. Once the cooling therapy is completed, we slowly warm the baby back up to inhibit the production of additional chemicals and reduce the risk of brain damage.
Dramatic, long-term results
Our faculty participated in a multi-site trial published in the New England Journal of Medicine in 2005 that led to total body cooling becoming a mainstream therapy. The data showed that 13% fewer babies died in the cooling group compared with the control group and 11% fewer developed disabling cerebral palsy.
A subsequent study, the TOBY trial, found that 13% more infants who were cooled for HIE had an IQ of 85 or higher at age 6 or 7 compared with the control group. This study supported the potential for long-term positive effects from the therapy.
Which babies can benefit from total body cooling?
As soon as a labor emergency is identified, the delivery team contacts the NICU with details of the situation and to request they attend the delivery. After stabilizing the infant, the NICU doctor (neonatologist) examines the newborn for signs of possible brain injury or HIE, such as:
- Too much acid in the blood (a typical body response to low oxygen)
- Bloodwork that indicates kidney, heart, or liver injury
- Low Apgar scores that persist longer than 10 minutes
- Abnormalities on the baby’s neurologic exam including: Decreased spontaneous movement; abnormal breathing or heart rate pattern; inability to suck; poor tone (baby appears “floppy”) or decreased alertness
If the baby has several of these signs, we become concerned about possible brain damage from lack of oxygen. Under current standards of care, moderate to severe HIE qualifies for total body cooling. Studies are under way to determine whether babies with mild HIE might benefit as well.
How does the therapy work?
The goal is to start cooling within six hours of birth – the sooner the better. We place the baby on a special blanket that circulates water through it, which cools and eventually warms the baby. Then we place a small temperature probe in the baby’s esophagus to track his or her core temperature. This device is also connected to the water blanket – these devices “talk” to each other to maintain a stable environment for the baby.
We also place IV lines in the area where the umbilical cord was attached. Through these lines, we give the baby fluids and draw blood samples to monitor organ function. Next, we attach the baby to an EEG machine to monitor for seizures.
We slowly lower the baby’s body temperature to 33.5 degrees Celsius (92.3 degrees Fahrenheit). The baby will stay at that temperature for 72 hours, a standard based on a 2012 study published in the Journal of Clinical Neonatology. Interestingly, a 2014 study found that a cooler temperature or longer duration of cooling did not benefit babies.
After five to seven days, we perform an MRI to look for injured areas in the baby’s brain. As a team, NICU doctors and neurologists discuss the imaging, details of the birth event, and initial exam information to estimate the physical or cognitive challenges, if any, the baby might face down the road.
We typically recommend close follow-up as the baby grows. Infants have a remarkable ability to heal from brain damage – more so than adults – so it can be difficult to speculate the extent of long-term cognitive or physical issues after a traumatic labor event.
Labor emergencies that might warrant cooling therapy
We monitor patients closely during labor for signs of conditions that can lead to restricted blood flow and infant brain damage. Here are some examples of rare birth events that usually result in emergency delivery and the potential for total body cooling:
- Placental abruption: The placenta pulls away from the uterine wall before delivery, depriving the baby of blood, nutrients, and oxygen. This rare situation typically occurs in the third trimester and is characterized by abdominal pain, back pain, and vaginal bleeding. Placental abruption occurs in approximately 7 to 12 of 1,000 pregnancies in North America and is more prevalent in women with high blood pressure and in those who use drugs such as cocaine that cause spasms in the blood vessels.
- Uterine rupture: The uterus tears during labor, causing the placenta, baby, or both to leave the uterus and enter the abdomen. Uterine rupture typically occurs in women who attempt vaginal birth after cesarean section (VBAC). We monitor the fetal heart rate tracing and contractions to detect this emergency as soon as possible. Symptoms can include fetal distress and significant bleeding. Uterine rupture occurs in approximately 1 in 1,146 pregnancies. (The rate is typically higher among women who have had one or more uterine surgeries.)
- Umbilical cord prolapse: When the bag of water breaks at the onset of labor, the umbilical cord can slip through the partially dilated cervix. If the cord is squeezed between the baby’s and mother’s bodies, the baby might not receive enough blood and oxygen. In spontaneous labor, we can’t plan for the water breaking. However, in induced labor, we break the water when the head is low enough in the pelvis that it touches the cervix, leaving limited room for the cord to slip out. Umbilical cord prolapse occurs in 1 to 6 of 1,000 deliveries.
- Amniotic fluid embolism: If amniotic fluid enters a patient’s bloodstream, she can go into shock, essentially causing respiratory failure, cardiovascular collapse, and heavy bleeding. We watch for early warning signs, such as fetal distress, maternal agitation, and skin discoloration. This extremely rare condition occurs in approximately 1 in 40,000 deliveries in North America.
These labor emergencies are rare, and we monitor patients closely to catch these concerns at the first sign of trouble. The faster we can care for the mother and assess the baby for cooling therapy, the better.
The future of total body cooling
Today, total body cooling is recommended for babies who are 35 weeks gestation or older with moderate to severe HIE. In the future, we hope to determine whether more premature babies might benefit from cooling. We have limited data suggesting babies might benefit from the therapy at 34 weeks gestation, but we need further research.
A study on cooling for younger preemies is under way. However, it is slow-going – labor events that cause HIE are rare, so it’s uncommon to see younger preemies born under these circumstances. Along with this study, there is a trial under way to determine whether babies with mild HIE also might benefit from total body cooling.
As you are thinking through where you want to deliver your baby, ask each hospital or birth center whether they can detect and handle emergency labor situations. Ask whether they offer total body cooling should your baby need it.
Preemie reunion party
She came into this world weighing less than a pound. Now, Celeste Salgado is celebrating life as a healthy and vibrant 10-year-old. She and several other former preemies recently reunited with their Neonatal Intensive Care Unit heroes at UT Southwestern's William P. Clements Jr. University Hospital.