Objectives: This meta-analysis aimed to determine the accuracy of the respiratory variations in aortic peak flow velocity (delta Vpeak) in predicting fluid responsiveness and the moderators of that accuracy. Data Sources: We performed searches for studies that used delta Vpeak as a predictor of fluid responsiveness in mechanically ventilated children in PubMed, Embase, Scopus, and CINAHL from inception to June 20, 2022. Study Selection and Data Extraction: Fifteen studies (n = 452) were included in this meta-analysis. The diagnostic test data of the included studies were synthesized as pooled sensitivity, specificity, and diagnostic odds ratio (DOR) and the area under the curve (AUC) of the summary receiver operating characteristic of delta Vpeak. Data Synthesis: The delta Vpeak cutoff values applied in these studies had a median of 12.3% (interquartile range, 11.50–13.25%). The pooled sensitivity and specificity of delta Vpeak were 0.80 (95% CI, 0.71–0.87) and 0.82 (95% CI, 0.75–0.87), respectively. The DOR of delta Vpeak was 23.41 (95% CI, 11.61–47.20). The AUC of delta Vpeak was 0.87. Subgroup analyses revealed that the accuracy of delta Vpeak was not moderated by ventilator settings, measures of delta Vpeak, gold standard index, the cutoff gold standard value of responders, type and volume of fluid, duration of fluid challenge, use of vasoactive drugs, general anesthesia, and cardiopulmonary bypass. Conclusions: By using the cutoff of approximately 12.3%, the delta Vpeak appears to have good accuracy in predicting fluid responsiveness in mechanically ventilated children. The moderators of delta Vpeak predictability are not found.

Highlights Abstract Aim: Pediatric femoral central venous catheter insertion is sometimes difficult due to small vein size. External iliac vein (EIV) compression may provide a tourniquet effect to the femoral vein (FV) and may facilitate catheterization. This study was conducted to determine the effect of EIV compression on FV size and femoral venous catheterization success rates. Methods: This study had 2 parts. The first part was a single-arm experimental study. The second part was a randomized controlled trial. Children weighing 2.5–15.0 kg were included. First part: All patients received the same intervention and measurements. FV anteroposterior and medial-lateral diameters were measured by ultrasound without EIV compression, after which EIV was compressed using the assistant’s finger, and FV diameters were measured. Second part: Patients were randomized into compression and control groups. The compression group received EIV compression during femoral venous catheterization. The control group did not receive the compression. Results: A total of 30 patients (15 in each group) participated. EIV compression significantly increased FV anteroposterior diameter (3.36 ± 1.01 mm with compression, 2.39 ± 0.76 mm without compression, mean difference = 0.97 mm, 95% CI = 0.73, 1.21, P < 0.001) and medial-lateral diameter (4.58 ± 1.40 mm with compression, 3.86 ± 1.32 mm without compression, mean difference = 0.72 mm, 95% CI = 0.43, 1.01, P < 0.001). Catheterization success rates were not different between groups. Conclusions: EIV compression increased FV size, but the effect on femoral venous catheterization success rates was inconclusive due to a small sample size.