Angulated Versus Traditional Peripheral Intravenous Cannulas: A Systematic Review and Meta-Analysis of Ease of Insertion, Flow Characteristics, and Catheter Longevity

Abstract

Background: Peripheral intravenous (IV) cannulation represents one of the most frequently performed invasive medical procedures worldwide, undertaken in 60–80% of all hospitalised patients. Despite its ubiquity, the procedure is associated with significant challenges, including first-attempt failure rates of 20–40%, patient discomfort, and premature catheter failure occurring in up to 40–50% of cases prior to therapy completion. The 5° angulated (preformed) venflon has emerged as a device innovation designed to improve anatomical alignment with peripheral veins, potentially enhancing procedural success and clinical performance. Objectives: To systematically evaluate and synthesise all available comparative evidence on the clinical performance of angulated (preformed) peripheral IV cannulas versus traditional straight venflons, with respect to ease of insertion, cannulation time, catheter longevity, patient-reported pain, and haemodynamic stability. Methods: This systematic review and meta-analysis was conducted in strict adherence with PRISMA 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Six electronic databases were searched (PubMed/MEDLINE, Cochrane CENTRAL, Embase, CINAHL, Scopus, and Google Scholar) from inception to December 2025. Eligible study designs included randomised controlled trials (RCTs) and prospective comparative cohort studies enrolling adult hospitalised patients requiring peripheral IV cannulation. Two independent reviewers performed screening, data extraction, and quality assessment. Risk of bias was evaluated using the Cochrane RoB 2 tool for RCTs. Pooled effect estimates were computed using the Mantel-Haenszel method for dichotomous outcomes (odds ratio, OR) and the inverse variance method for continuous outcomes (weighted mean difference, WMD). Heterogeneity was quantified using the I² statistic and Cochran’s Q test. Subgroup analyses and sensitivity analyses were pre-specified. Results: Four studies met the eligibility criteria for qualitative synthesis; one RCT (n = 100; 50 per group) contributed to quantitative meta-analysis. Angulated venflons demonstrated a statistically significant and clinically meaningful advantage in ease of insertion (68.0% vs. 2.0% classified as easy; OR = 120.4; 95% CI: 15.2–953.1; p < 0.001) and reduced cannulation time (WMD = −3.52 min; 95% CI: −3.88, −3.16; p < 0.001). Conversely, traditional venflons exhibited significantly superior catheter longevity (WMD = −15.68 h; 95% CI: −19.15, −12.21; p < 0.001), favouring conventional devices by approximately 15.7 hours of additional functional dwell time. Post-procedural Visual Analogue Scale (VAS) pain scores at 5, 15, and 30 minutes showed statistically significant but clinically marginal differences, with both groups remaining in the mild-discomfort range. Haemodynamic parameters (mean arterial pressure [MAP] and heart rate) were stable and comparable across all time points in both groups. Conclusions: The 5° angulated venflon provides clinically significant advantages in procedural ease and efficiency but is associated with reduced catheter longevity compared with traditional straight venflons. A context sensitive approach to cannula selection is recommended: angulated devices are preferred in emergency, perioperative, and high-turnover settings, while traditional venflons remain advantageous where prolonged IV therapy is anticipated. Large-scale, multicentre RCTs are urgently needed to consolidate the evidence base, inform device selection guidelines, and investigate design modifications that could combine the insertion benefits of angulated geometry with the durability of conventional straight cannulas.