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Abstract

We thank Meyer and Giannopoulou for their comments. We agree that no firm statements about safety and, for that matter, efficacy can be made from a feasibility pilot trial of vasopressin (n = 10) vs dopamine (n = 10) as first-line therapy of early hypotension in extremely low birth weight (ELBW) infants. We were cautious not to overemphasize our results, and we unequivocally state that the performance of a larger randomized, controlled trial is in order. We did not implicitly state the initial dose of vasopressin that was used in our study, although it was implied by our infusion rate of 0.2 mL/kg/h, which translated to our starting dose of vasopressin 0.01 units/kg/h (0.0002 units/kg/min). Our dose range, from 0.01-0.04 units/kg/h, is well within the manufacturer's recommendation. We disagree, however, that a trial of vasopressin vs noradrenalin would have been more meaningful than our head-to-head comparison of vasopressin vs dopamine in ELBW infants. Dopamine is the most commonly used vasopressor and noradrenalin is rarely used.1Rios D.R. Moffett B.S. Kaiser J.R. Trends in pharmacotherapy for neonatal hypotension.J Pediatr. 2014; 165: 697-701Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar It was our intention to investigate a medication that could potentially replace dopamine as a first-line agent in hypotension to avoid potential side effects associated with dopamine use in this vulnerable population. Consistent with most other hypotension treatment studies in ELBW infants, we did not discriminate and enroll subjects according to the underlying etiology of hypotension. In our ongoing research, we will be investigating methods of objectively determining the etiology of hypotension in ELBW infants and agree that the topic is of utmost importance to efficiently and appropriately treat these infants. Further, even though Meyer and Giannopoulou observed that vasopressin may be helpful in improving blood pressure in catecholamine-refractory septic shock in ELBW infants with acute renal injury (n = 3) vs those without septic shock (n = 3),2Meyer S. Gottschling S. Baghai A. Wurm D. Gortner L. Arginine-vasopressin in catecholamine-refractory septic vs non-septic shock in extremely low birth weight infants with acute renal injury.Crit Care. 2006; 10: R71-R76Crossref PubMed Scopus (64) Google Scholar the population and intent of use of vasopressin was different than in our study. Although none of the infants in our study who received vasopressin had sepsis, 90% responded with improved blood pressure. We postulate that abnormal peripheral vascular regulation may also be present in ELBW infants with hypotension without sepsis, thereby potentially explaining the usefulness of vasopressin as a first-line agent. We agree that vasopressin pharmacokinetic data are important. We have since developed and validated a micro-volume assay3Zhang D. Rios D.R. Tam V. Chow D.S. Development and validation of a highly sensitive LC-MS/MS assay for the quantification of arginine vasopressin in human plasma and urine: application in preterm neonates and child.J Pharm Biomed Anal. 2014; 99: 67-73Crossref PubMed Scopus (15) Google Scholar that will be used in our future studies. Vasopressin in arterial hypotension in extremely low birth weight infantsThe Journal of PediatricsVol. 167Issue 2PreviewRios and Kaiser demonstrated that vasopressin is as effective as dopamine in increasing arterial blood pressure in extremely low birth weight infants with early arterial hypotension.1 We would like to comment on their work. Full-Text PDF