The choice of vasopressor and umbilical artery pH

  • Sun-Kyung Park
  • Won Ho KimEmail author
  • Jin-Tae Kim
Letter to the Editor


Phenylephrine Cesarean section Post-spinal hypotension 

To the Editor:

We read with great interest the study by Kaneko et al. [1]. Kaneko et al. first reported the influence of vasopressor in parturients with the hypertensive disorder of pregnancy. The authors correctly performed propensity score matching, which is known to exhibit more empirical power than logistic regression analysis when the number of events is low [2]. In their propensity score matching, parturients who administered phenylephrine or ephedrine were matched with those with ephedrine. To evaluate the effect of choice of vasopressor, those with phenylephrine should be matched with those with ephedrine. Furthermore, although there was no significant difference in the dose of ephedrine after matching, the use of statistical hypothesis test to evaluate balance before and after matching is widely criticized [3]. The simplest accepted method is to calculate the standardized difference. Therefore, we cannot be sure that there was no difference in the dose of ephedrine between the matched groups. Along with these methodological issues, as this was a retrospective study with no strict criteria regarding selection and use of vasopressor, a firm conclusion should be delayed until further prospective randomized trials.


Compliance with ethical standards

Conflict of interest

No competing interest declared.


  1. 1.
    Kaneko T, Kariya N, Hirose M. Association between intraoperative phenylephrine administration and umbilical artery pH in women with hypertensive disorders of pregnancy: a retrospective cohort study. J Anesth. 2018. Scholar
  2. 2.
    Cepeda MS, Boston R, Farrar JT, Strom BL. Comparison of logistic regression versus propensity score when the number of events is low and there are multiple confounders. Am J Epidemiol. 2003;158:280–7.CrossRefGoogle Scholar
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    Austin PC. Propensity-score matching in the cardiovascular surgery literature from 2004 to 2006: a systematic review and suggestions for improvement. J Thorac Cardiovasc Surg. 2007;134:1128–35.CrossRefGoogle Scholar

Copyright information

© Japanese Society of Anesthesiologists 2019

Authors and Affiliations

  1. 1.Department of Anesthesiology and Pain MedicineSeoul National University Hospital, Seoul National University College of MedicineSeoulRepublic of Korea

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