Variation in the outer diameter of vascular sheaths commonly used in infant cardiac catheterization

Objective: To compare the outer diameter (OD) of conventional and radial sheaths from different manufacturers for sizes typically used in infant catheterization. Background: The smallest sheath size is recommended to minimize risk of arterial injury in infants. However, sheath size refers to its internal diameter (ID), but it is the larger OD that determines risk. The OD varies between manufacturers and is frequently not known to the end user. Methods: Three authors measured the OD of 3, 3.3, 4, 5, and 6 French (Fr) sheaths from different manufacturers using a Mitutoyo digital micrometer. Continuous variables are reported as mean ± SD. The midshaft and proximal-shaft sheath measurements were compared using an independent samples t test. Agreement between author measurements was tested using intra- and inter-rater reliability analysis. Manufacturer sheath OD measurements were obtained. Statistical significance was set at p <.05. Results: There was no difference in the measured sheath diameters at the midpoint and proximally (p <.05). The intra-rater and inter-rater reliability were excellent (Intraclass correlation coefficient 1.0). Among conventional sheaths the OD varied between manufacturers, Terumo sheaths had the smallest and Galt sheaths had the largest OD. Radial sheaths had the smallest OD (1 Fr smaller) when compared to similar sized conventional sheaths. For instance, the OD of 4 Fr radial sheath (1.610 ± 0.006 mm) is essentially the same as the OD of the conventional 3 Fr (1.644 ± 0.016 mm) and 3.3 Fr (1.635 ± 0.005 mm) sheaths. Conclusions: Our study shows variation in the OD of sheaths used in infant catheterization. The radial sheaths offer the smallest OD across sizes.