Factors that affect longevity of intravenous cannulas: a prospective study

Background: Few guidelines exist to guide medical personnel on the most successful means of achieving sustained intravenous cannulation. This study examines the impact of gauge and site of intravenous cannulas (IC) on the longevity of ICs in hospitalized patients. Methods: A prospective study was conducted on 500 ICs inserted into patients of St Vincent's Private hospital from December 2005 to June 2006. Patients were followed until the IC had been removed or changed. Statistical analysis was performed using Cox proportional hazards. Results: Of the 500 ICs inserted, 37% were 18g, 46% were 20 g and 18% were 22 g. Gauge of IC was the most significant predictor of increased longevity of IC (P=0.0002, RR=1.17, 95% CI 1.08-1.27). The median survival of 18, 20 and 22 g were 57 h (95% CI 49-72), 43 h (95% CI 36-48.5) and 29 h (95% CI 24-40.5), respectively. The site of IC placement influenced the longevity of ICs (P = 0.005, RR = 0.7, 95% CI 0.55-0.9), as did male gender (P = 0.03, RR=0.76, 95% CI 0.6-0.97). However in subgroup analysis, the most marked effect on IC longevity was evident in those patients with 18g placed in the forearm/wrist (median 72h) with less marked changes in other site/gauge combinations. In contrast, 22 g ICs placed in the hand had a median lifespan of 29 h. Conclusion: IC gauge and site of placement are important factors in determining IC longevity. 18 g ICs placed in the forearm/wrist can considerably increase the longevity of ICs and should be attempted in patients who require sustained cannulation.