A comparison of different methods of lubrication of glass syringes used to identify the epidural space.

Measurement of loss of resistance in glass syringes is a method widely used to locate the epidural space in epidural anaesthesia. Static and dynamic forces were measured under four experimental conditions in new glass syringes: unpolished, dry; polished, dry; unpolished, saline lubricated; and polished, saline lubricated. The unpolished saline lubricated syringes had a mean (SD) static force of 53.18 (15.0) g and dynamic force of 40.88 (15.2) g. These values were significantly greater than for polished dry syringes where the values were 5.27 (2.1) g and 4.38 (0.94) g, respectively. The results show that the least amount of resistance to plunger movement is obtained by dry polishing glass syringes.