Plasticizer, Di(2-ethylhexyl)phthalate (DEHP), exposure in neonatal ECMO vs. near-miss ECMO patients

Objective: The plastic used in many medical devices is composed primarily of the plastic polyvinyl chloride (PVC). PVC is made flexible by treating it with chemical compounds called plasticizers. The most commonly used plasticizer is di(2-ethylhexyl) phthalate (DEHP). The general population is exposed daily to DEHP and one of its many metabolites, mono(2-ethylhexyl) phthalate (MEHP), primarily through food and aerosolization of environmental exposure. Exposure rises dramatically in premature or ill neonates, who are exposed to medical devices including enteral, blood and infusion bags, tubes and infusion devices. The rate of leaching of DEHP depends on many factors, including contact with lipophilic solutions and the amount of DEHP found in the product. Highly lipophilic substances readily extract plasticizers from PVC bags and tubes. Our objective was to determine the concentration of DEHP and MEHP in the urine of infants undergoing extracorporeal membrane oxygenation (ECMO) and near-miss ECMO to determine if ECMO results in increased concentrations of DEHP and MEHP in the urine. Study design: Using an in vivo prospective comparative study design, we evaluated 12 term or near-term neonates requiring ECMO. Our control population included 17 neonates with similar underlying diagnoses, referred to our NICU for ECMO but who ultimately responded to maximal medical therapy without ECMO. Two baseline urine samples were collected on admission to the NICU for DEHP and MEHP analysis on both the ECMO and near-miss populations. Daily urine samples were collected sequentially for five days in both populations. Urine samples were collected prior to discharge/transfer for both populations. Urinary DEHP and MEHP analysis was performed using tandem mass spectroscopy. Demographic data was collected for each patient. Results: We enrolled a total of twenty-nine patients in the study. All patients were transported to our NICU from outside birthing centers. Twelve neonates required ECMO support. The other seventeen patients responded to maximal medical therapy without ECMO. The mean DEHP for the ECMO group was 38.0 (95% CI=29.6, 47.5) compared to 33.0 (95% CI = 26.6, 40.1) in the near-miss group. The mean MEHP for the ECMO group was 29.8 (95% CI=22.4, 38.2) compared to 26.1 (95% CI=20.6, 32.3) for the near-miss group. Conclusion: Even though urinary levels of DEHP and MEHP were slightly higher in the ECMO group compared to the near-miss group, these differences were not statistically significant.