Editor’s Note: Dr. Morgan Irwin-Weyant is a pediatric resident. She plans to pursue a career in pediatric emergency medicine.
-Rachel Y. Moon, MD, Associate Editor, Digital Media, Pediatrics
Several weeks ago during a single clinic day, we sent three 2-week-old infants to the emergency department (ED) for evaluation for hypothermia. Despite our best efforts with bundling and utilizing new thermometers, their body temperatures simply would not increase.
For each of these infants, we were concerned about a serious bacterial infection (SBI). However, the sepsis workup for each of the infants was negative for bacterial infection.
After this recent experience, I was intrigued to read a Research Brief by Dr. Christopher Graves from WakeMed Health and colleagues from four other institutions, entitled “Hypothermia in Young Infants,” which is being early released by Pediatrics this week (10.1542/peds.2022-058213).
The authors sought to determine diagnoses other than SBI that might be associated with temperature instability in infants.
This study evaluated 2,826 infants who were hypothermic, defined as children < 90 days of age with temperatures <36.4, from four pediatric EDs, using retrospective chart review to identify diagnoses unrelated to SBI that may explain these infants’ temperature instability. The infants were further stratified into admitted to the hospital or discharged from the ED, as well as by age: 0–30 days, 31–60 days, and 61 –90 days. Similar to my experience in clinic a few weeks ago, the most common diagnosis in infants under 31 days who were admitted is disturbances of temperature regulation of newborn. However, a surprising number of these infants, both admitted (17.9%) and discharged (11.1%), had elevated hyperbilirubinemia. Older infants who were hypothermic and admitted, both 31–60 days and 61–90 days, were more likely to be diagnosed with bronchiolitis, while those who were discharged were frequently diagnosed with nausea and vomiting.
The authors also found that among admitted infants, colder temperatures were significantly associated with a chronic condition, defined as one expected to last > 12 months and/or increase risk of hospitalization. Older infants were more likely to be diagnosed with a chronic condition than younger infants.
The authors speculate that physiologic factors, such as less subcutaneous fat and larger surface area, inherent in younger infants may make them more susceptible to environmental or other benign causes of hypothermia.
If you care for infants, this is a good study to review. While it does not entirely answer the question of what to do in these cases, this may broaden your differential diagnosis when considering an infant with hypothermia.