['Little is known about the direct effect of pneumoperitoneum (PP) on microcirculation and its influence on the quality of tissue perfusion. This study aimed to investigate the intraoperative effects of carbon dioxide (CO2) gas PP on microcirculation density and perfusion in neonates receiving laparoscopic surgery for hypertrophic pyloric stenosis.', 'In a single-center observational study, the oral microcirculation in 12 neonates receiving laparoscopic pyloromyotomy was investigated. Intraoperative hemodynamic parameters, intermittent buccal mucosa capillary density measurements (pre- and postoperative), and continuous intraoperative sublingual microcirculation measurements (i.e., vessels with a diameter <25 μm) of total vessel density, perfused vessel density, proportion of perfused blood vessels, blood vessel diameters (BVd), and microvascular flow index were obtained before (at baseline), during, and after PP insufflation for all patients using sidestream dark-field imaging for the duration of the complete surgical procedure.', 'With the exception of a significantly elevated end-tidal CO2 (34 ± 4-40 ± 8 mmHg; p < 0.05 vs before [baseline], one-way analysis of variance [ANOVA]) during intraoperative insufflation, no significant differences were found between time points for the intraoperative hemodynamic parameters. Pre- and postoperative buccal capillary density showed no significant changes in mucosal perfusion. Analysis of continuous intraoperative sublingual microcirculation parameters exhibited a statistically significant increase in BVd during insufflation (8.8 ± 2.4-9.3 ± 2.5 μm; p < 0.05, one-way ANOVA) and a significant decrease after exsufflation (8.2 ± 2.3 μm; p < 0.01 vs during insufflation and p < 0.05 vs baseline, one-way ANOVA, respectively). No other significant differences were found between time points for the remaining microcirculatory parameters.'] Does carbon dioxide gas pneumoperitoneum induce minimal microcirculatory changes in neonates during laparoscopic pyloromyotomy?