Living in San Diego makes the beach scene quite a familiar sight for me. Lying on the beach, after a swim, I viscerally recognize the importance of keeping warm after being in colder ocean waters. One of the beauties of the sandy beach is the thermal radiance that emanates from the ground that has stored up heat from the sun beating down onto it. Lying on a blanket, the heat is soothing; regardless of the wet skin’s exposure to wind it can feel extremely comfortable.
Moreover, the body seems to form fit into the sand, adding to this comfort. Sometimes this makes me think how our naked preemies fare on their “sandy beach” in the NICU and how we may have not figured it all out yet.
The ability to provide warmth to babies is a fundamental necessity for survival. We are taught through NRP guidelines the importance of establishing normothermia and how detrimental starting off cold can be affecting early metabolic stability and later susceptibility to morbidities.1 It has been well known that adults undergoing surgery suffer much higher infection rates if they have periods of hypothermia during the perioperative period.
So how do we heat our babies in the NICU? In the delivery room we rely on a combination of warm ambient room temperature, overhead radiant heating, use of plastic covers, and in more vulnerable situations such as less than 1000 gram birth weight, the use of a disposable chemical heating mattress to maintain temperature. In the NICU our incubators are sophisticated, thick-walled chambers that can introduce high humidity and reduce evaporative water losses that help to maintain an infant’s body temperature. The thick plastic exteriors trap heat and moisture inside. On rounds I often liken the incubator to a terrarium by its looks. However, there is one important difference: our incubators are never completely closed. Each time we open two-sided ports to access and examine our babies, the “seal is broken,” and we permit humidity and heat to escape. Further, every unit has sick infants in an open warming bed which are subject to convection currents of cold air every time someone walks by. Our current NICU at UCSD is getting quite old (new one in two years, finally!) and therefore can never get regional room temperatures stable most of time, which makes maintaining temperatures for babies in open beds even more challenging. The inefficiencies of how we warm infants has me perplexed; I’m not quite sure how we ended up heating babies like we do.
The ability to heat efficiently and effectively is not simple. Having grown up in Toronto, Canada, I was very familiar with radiator heating systems. This was because my wife and I had an affection for older Victorian style houses, and we lived in several different brick houses that dated between 70 to 80 years old. These old houses had radiant heat emanating from water radiator systems. This provided a nice steady heating method. The biggest liability with such radiator systems was that they were slower to warm and cool down, and therefore less responsive. Now, most houses and buildings are heated with warm air through air duct systems that blow warm currents (and dust) around. I always seemed to feel warmer in radiator systems once they got fired up. I much prefer radiant floor heating systems as are frequently used to heat homes in many parts of Asia because of the recognized comfort of this practice. For a couple of years in Toronto, my family had first-hand experience with radiant floor heating when we tried experiment living in a prototype eco-friendly house. I can tell you that there was nothing more comfortable in the midst of a Canadian winter than to be walking barefoot indoors on concrete.
Mothers know early on in pregnancy to recognize the positive impact of human contact and warmth. In the womb this comes in the form of a soothing voice, gentle movements and/or the surrounding warmth the fetus is bathed in. Immediately after birth we recognize that, for the healthy term or late preterm infant immediately after birth, providing skin-to-skin care (SSC) with baby on mother’s chest is the most natural way to maintain core body temperature and confer initial psychosocial bonding and breastfeeding cues.
The benefits of SSC are well described. Both preterm and term infants have been found to have better temperature regulation, reduced energy expenditure, higher and more stable blood glucose levels, improved sleep states, and better long-term neurodevelopmental outcomes. Recently I was reminded of this with one of our infants with severe chronic lung disease who had a high frequency of desaturations. The nurses and I noticed that each time a mother had SSC time, the desaturations frequently disappeared completely. I really don’t think that we fully maximize these type of benefits. Also it is impossible at present to measure some of the psychosocial benefits of being close to another human being other than inferring from differences in outcomes.
A few years ago I got a team of engineering students to build a warming mattress for babies. We got the materials figured out quickly but the generation of heat was particularly challenging. It was eye opening to see how much electrical power it took to maintain a warm surface, and this introduced some safety concerns, especially if the mattress were to get wet. The irony in all this is that the human furnace is the most natural and sustainable source of heat for small infants and is underutilized in the NICU at present.
Data also supports that physical touch supports improved growth; the mere increase in physical touch time appears to be important in triggering normalizing physiologic responses in vulnerable preemies in helping them grow.2 However, practically every day I am making rounds in the NICU I am kindly told by my neighborhood bedside nurse not to disturb our infants while they sleep. They need their developmental rest with peace and minimal handling. Leave them alone and keep the noise down. I feel somewhat handicapped when I examine an infant and recognize his/her innate instincts to be touched, recognizing that I cannot fully satisfy this need. Recent data suggests that sensory deprivation in quiet single patient room settings may not be such a good thing for our infants.3 Making the wholesale move to single patient rooms in an effort to supposedly improve newborn care, along with improved parental satisfaction, is now being questioned. In our NICU, as is with most within a 24 hour period, we are lucky to give human touch more than twenty percent of the time to most of our infants. The original intent of the Bogota experience, where kangaroo care was first introduced, was to provide human capital as an integral part of the medical care. Parents are very willing to give their time for their infants. Resolving this practical dichotomy is going to take some time as trading our current kind of overt medicalized care for a softer human one will require a huge paradigm shift.
So what does the future hold? Will our infants be wearing body suits just like the surfers in the Pacific Ocean in the middle of January to keep their core warm? I think more needs to be done by our profession to rethink how we do things and where we should go with infant warming. I stated in a past blog that we act as “baby whisperers,” trying to tune into the best needs of our infants. When it comes to keeping our babies warm, perhaps we need to listen a bit harder.
1. Neonatal Resuscitation. Textbook. American Academy of Pediatrics and American Heart Association. Sixth edition.
2. Field T et al. Potential underlying mechanisms for greater weight gain in massaged preterm infants. Infant Behav Dev. 2011 Jun;34(3):383-9.
3. Pineda RG et al. Alterations in brain structure and neurodevelopmental outcome in preterm infants hospitalized in different neonatal intensive care unit environments. J Pediatr. 2014 Jan;164(1):52-60.e2.