Evaluating Precision of Therapy - Milrinone

The proposed trial is a pilot of an open label, randomized trial of milrinone therapeutic drug monitoring in patients < 18 years treated with milrinone following open-heart surgery for congenital heart disease at the Hospital for Sick Children, Toronto. We will randomize patients to (1) receiving therapeutic drug monitoring or (2) control patients who receive standard care. Standard care involves titration of milrinone infusion based on clinical examination by the treating team. Control patients will have milrinone plasma levels drawn but not analysed until the end of the study. The intervention is (1) regular measurement of milrinone levels; and (2) physician feedback of plasma levels in experimental arm by the ICU pharmacist. After obtaining consent, eligible subjects will be allocated to a trial group by random assignment (sealed envelopes) within 3 strata in a 1:1 allocation. These strata are < 2 years, 2- 10 years and > 10 years to ensure equal distribution of these age ranges in each group for pharmacokinetic analysis. For the intervention group, sampling for milrinone levels will occur at 0 hours (upon arrival to ICU with routine admission blood collection) and approximately every 6- 8 hours (whenever the line is accessed for routine blood work). The last sample will be taken 6-8 hours after cessation of infusion, or if the patient leaves the ICU, or the maximum amount of blood sampling has been reached or after 7 days for children weighing more than 8 kgs (or 5 days for children weighing less than 8 kgs), which ever comes first. Follow-up will be exclusively during the period of hospitalization in the ICU until ICU discharge. An optional algorithm with a proposed titration for milrinone will be provided for use at the discretion of the treating team. Clinical outcomes will be measured as a composite outcome of dysrhythmia, LCOS and death.