We determined pulse oximetry and heart rate at baseline (after pain relief intervention but before beginning circumcision) and at 1-minute intervals during the procedure. Total procedure time and crying time were assessed later by viewing a videotape of the infant. Pain behavior scores were also independently determined at 30-second intervals by each investigator during videotape reviews using the MBPS.24
Continuous variables were compared using analysis of variance (ANOVA) and the Student t test. We compared pain behavior scale determinations at each 30-second mark with a 3-way ANOVA using time as repeated measures and a Scheffe test for pair-wise comparisons between groups.
Results
The baseline values are shown in Table 2. The DPNB group differed at baseline with respect to the D50 group in time since last fed and heart rate. No other significant differences were noted.
Table 3 shows the data obtained from the circumcision procedures. Mean heart rate differed significantly among the 3 groups, with the D50 group having the highest mean heart rate. However, the percentage increase in heart rate did not differ between the D50 group and the placebo group. No other differences were noted between the D50 group and the placebo group. Mean pulse oximetry measurements and percentage of crying time also differed significantly between the DPNB group and the other 2 groups.
The data from the modified behavioral pain scale confirmed the findings from the crying time, heart rate, and pulse oximetry measurements. The 3-way ANOVA test showed that the MBPS score varied significantly by patient group and by the time when it was measured (P <.001). The Scheffe test for pair-wise comparisons showed that the DPNB group exhibited significantly less pain behavior than either the placebo or dextrose groups (P <.001).
Discussion
Administration of concentrated dextrose solution before circumcision does not offer adequate analgesia. For all pain-related measures (heart rate, pulse oximetry, crying time, and MBPS), there were no statistically significant differences detected between the placebo group and the D50 group.
The baseline differences between the 3 groups studied include the time since last feeding and heart rate. The time since last feeding does not seem to be clinically significant. The higher heart rate in the D50 group may be a result of the high glucose load. The findings of the experiment should not be affected by these differences.
The DPNB group showed significant differences in heart rate, pulse oximetry, crying time, and pain scale scores compared with the other 2 groups during circumcision. This fact reinforces that the study size was adequately powered to detect differences in these parameters and that DPNB provides pain relief for neonatal circumcision. No comparison was done using a topical agent or the circumferential ring block, although previous research has shown these methods to be similar, or in some cases superior, to DPNB.14
Our results differ from those of Herschel and colleagues,23 who found a benefit from sucrose administered through a pacifier. Their study compared changes in heart rate, oxygen saturation, and pain-related behavior among 3 study groups: no treatment, DPNB, and delivery of a 50% sucrose solution through a nipple held in place during the procedure. They found significant improvement in pain measures with the sucrose pacifier group. A potential flaw in this study is use of a nipple to deliver the sucrose. The suckling action of the infant on the pacifier alone may have produced analgesia. Our study eliminates the potential effects of suckling on pain-related behavior and physiologic responses.
Limitations
One drawback to our study concerns the use of D50 versus a concentrated sucrose solution. We chose D50 because of its ready availability, compared with a nonstandard solution like sucrose, and because in animal studies the specific type of oral solution used (eg, milk, various sugars, fats) did not alter the measured analgesic effect.25 Further study using a concentrated sucrose solution should be considered before dismissing this form of analgesia entirely.
Conclusions
Future study comparing concentrated sucrose, DPNB, or superficial ring block, and topical local anesthetics would further clarify the issues brought up by our study. Also, the antinociceptive properties of suckling during circumcision should be evaluated. For now, the readily available concentrated glucose solutions, such as 50% dextrose, do not offer any advantage over placebo in relieving the pain associated with neonatal circumcision, and are inferior to a DPNB.