MICropsampling for CAffeine in PREMature Newborns

Caffeine is one of the top five most prescribed drugs in neonatology. Caffeine has many beneficial impacts on preterm infants (cardiac, neurologic and pulmonary). One of these beneficial impacts is to prevent apnea. However, despite its use in routine neonatal practice, there is currently no consensus on standardized protocols for caffeine administration concerning timing and dose and there is a lack of knowledge in the most immature preterm. High caffeine concentrations may lead to serious adverse events such tachycardia while low caffeine concentrations may lead to an upsurge apnea, and as a consequence to the necessity of mechanical ventilation.

A study demonstrated that highly variable caffeine concentrations where observed when a standardized dose was administered to preterm infants. However, while no correlation between caffeine concentration and the number of apneas has been reported, there is a correlation between caffeine concentration and heart rate in preterm infants. In addition, a retrospective study demonstrated that in infants born before 29 gestational weeks with a caffeine concentration \> 15 micrograms/ml was associated with a lower incidence of chronic lung disease, persistent ductus arteriosus, lesser number of days of ventilation and shorter length of stay in hospital. Based on these observations, therapeutic drug monitoring (TDM) of caffeine could be particularly relevant in preterm infants, in order to manage the risk of overexposure to caffeine in patients who need higher doses to prevent apnea. However, we are limited by the risk of anemia associated with repeated sampling in preterm infants. In our hospital, Caffeine is measured when children make apnea despite a dosage of 5 mg/kg and when children have potentials adverse events such tachycardia.

To avoid anemia due to repeated blood test for TDM, microsampling devices allowing analyses in very small volumes of blood could be used. Recently, microsampling devices have been developed for home-based capillary blood sampling and their use has been validated in different contexts, in particular the TDM of immunosuppressive drugs. These devices allow the collection of dried blood spots and present the advantages of being less invasive than venipuncture and collecting low volumes of blood for analysis. The analysis of caffeine in dried blood spot (DBS) has been developed with a good agreement between DBS and plasma concentrations in neonates. However, changes in hematocrit levels may impact concentrations measured in DBS. To avoid this, volumetric micro sampling (VAMS) devices such as the Mitra ® (Neoteryx®) have been developed with good results. With caffeine, VAMS effectively assisted in eliminating the effect of hematocrit and have good correlation with blood standard dosage.

In this context, the investigator propose a pilot study in preterm infants, in whom the microsampling device Mitra ® will be used for capillary blood sampling to collect caffeine for TDM. The (i) feasibility (ii) nurse satisfaction iii) analytical performances will be evaluated.

The hypothesis is that the use of a microsampling device such as Mitra ® will render possible caffeine TDM thanks to a good feasibility and to good pre-analytical and analytical performances of a method developed.