To the Editor:
We read with interest the article by Simpao et al.1 on fasting times and incidence of low blood pressures. The study found that prolonged clear fluid fasting was associated with increased odds of low blood pressure during the preincisional phase in anesthetized children, interestingly, in a nonlinear fashion. The definition of hypotension was based on the percentile reference curves from intraoperative blood pressure nomograms, reported by de Graaff et al.2 These reference curves were derived from the electronic anesthetic records of healthy American Society of Anesthesiologists (ASA; Schaumburg, Illinois) physical status I, II children.2 The study identified 889 patients with low systolic blood pressure during the surgical preparation phase, and 697 patients during the anesthesia preparation phase. Although ASA III, IV comprised only 9.2% (n = 1,433) of the entire study cohort (n = 15,543), we do not know if they contributed disproportionately to the hypotension results, as might be expected from a greater incidence of hemodynamic instability in ASA IV adult patients.3 This might affect the interpretation of the study results, and be of interest to journal readers.
Competing Interests
The authors declare no competing interests.