Ultrasonic investigation of the effect of topical glyceryl trinitrate on peripheral arm vein diameter: Implications for intravenous nutrition

Background: It has been suggested that topical glyceryl trinitrate (GTN) ointment may cause venodilatation and hence deter thrombophlebitis. However, objective evidence of an increase in vein diameter has not been demonstrated. Methods: B mode ultrasonography was used to measure arm vein diameter. In a prospective study, measurements were taken before and after 24 hours of exposure to topical GTN. Results: Reproducibility of vein diameter measurement was demonstrated. Basilic veins were larger than cephalic veins, but exposure to GTN ointment for 24 hours was not associated with measurable venodilatation. Conclusions: Ultrasonography enabled noninvasive measurement of intraluminal vein diameter. It is unlikely that GTN prevents thrombophlebitis in superficial arm veins by causing venodilatation.