Measures of Systemic Innate Immune Function Predict the Risk of Nosocomial Infection in Pediatric Burn Patients.

Critical injury-induced immune suppression has been associated with adverse outcomes. This acquired form of immunosuppression is poorly understood in pediatric burn patients, who have infectious complication rates as high as 71%. Our primary objectives were to determine if thermal injury results in early innate immune dysfunction and is associated with increased risk for nosocomial infections (NI). We performed a prospective, longitudinal immune function observational study at a single pediatric burn center. Whole blood samples from burn patients within the first week of injury were used to assess innate immune function. Nosocomial infections were defined using CDC criteria. Immune parameters were compared between patients who went on to develop NI and those that did not. We enrolled a total of 34 patients with 12 developing a NI. Within the first 3 days of injury, children whom developed NI had significantly lower whole blood ex vivo LPS-induced TNFα production capacity (434 pg/mL vs 960 pg/mL, P = .0015), CD14+ monocyte counts (273 cells/µL vs 508 cells/µL, P = .01), and % HLA-DR expression on CD14+ monocytes (54% vs 92%, P = .02) compared with those that did not develop infection. Plasma cytokine levels did not have a significant difference between the NI and no NI groups. Early innate immune suppression can occur following pediatric thermal injury and appears to be a risk factor for the development of nosocomial infections. Plasma cytokines alone may not be a reliable predictor of the development of NI.

Abnormal lymphocyte response after pediatric thermal injury is associated with adverse outcomes.

BACKGROUND: Burns are a leading cause of morbidity in children, with infections representing the most common group of complications. Severe thermal injuries are associated with a profound inflammatory response, but the utility of laboratory values to predict infections in pediatric burn patients is poorly understood. MATERIALS AND METHODS: Our institutional burn database was queried for patients aged 18 y and younger with at least 10% total body surface area burns. Demographics, mechanism, laboratory results, and outcomes were extracted from the medical record. Patients were classified as having an abnormal or normal total white blood cell count, neutrophil percentage, and lymphocyte percentage using the first complete blood count drawn 72 or more hours postinjury. Outcomes were compared between groups. RESULTS: White blood cell data were available for 90 patients, 84 of whom had neutrophil and lymphocyte percentages. Abnormal lymphocyte percentage 72 h or more after burn injury was associated with a significant increase in infections (67.9% versus 32.3%, P = 0.003), length of stay (33.1 versus 18.8 d, P = 0.02), intensive care unit length of stay (13.1 versus 3.7 days, P = 0.01), and ventilator days (5.8 versus 2.3, P = 0.02). It was also an independent predictor of infection (odds ratio 7.2, 95% confidence interval 2.1-24.5). CONCLUSIONS: Abnormal lymphocyte percentage at or after 72 h after burn injury is associated with adverse outcomes, including increased infectious risk.

The systemic immune response to pediatric thermal injury.

BACKGROUND: The immune response to critical injury, including thermal injury, can heavily influence the recovery and long term prognosis for patients suffering such insults. A growing body of evidence supports that a suppressed immunologic state following critical injury can lead to adverse outcomes for adult and pediatric patients. METHODS: A Pubmed literature search was conducted to review areas of the immune system that are impaired after thermal injury and identify key immune players that are potential targets for therapeutic intervention. The focus was pediatric thermal injury; however, where pediatric studies were lacking adult studies were used as reference. RESULTS: Changes in cytokine profiles and immune cell phenotypes have been observed following thermal injury. Treatment with immunomodulatory stimulants, including IL-7 and GM-CSF, lead to improved outcomes in critically ill patients and may also be useful tools to improve immune function in pediatric burn patients. CONCLUSIONS: The innate and adaptive branches of the systemic immune system are impaired following thermal injury in adult and pediatric patients. Immunomodulatory therapies currently being used in areas outside of thermal injury may be useful tools to help improve outcomes following pediatric thermal injury.