The Effect of 20 mL of Epidural Saline Predistention on Catheter Success and Quality and Spread of Sensory Blockade
Abstract Number: 272
Abstract Type: Original Research
Introduction: Malpositioned epidural catheters are a significant problem for obstetric anesthesiologists and occur in greater than 30% of laboring patients(1). Similarly, accidental intravascular placement of epidural catheters occurs in 7-16% of parturients, resulting in the need for additional catheter manipulation and possible replacement(2,3). Researchers have demonstrated benefits with smaller volumes of 5 or 10 mL of saline to distend the epidural space including reduced rates of intravascular placement and higher number of total dermatomes blocked(3,4). The optimal amount of saline for injection to achieve maximal benefit is clearly not known. The goal of this study is to compare in a controlled, randomized prospective fashion whether 0 versus 20 mL of epidural saline injection prior to catheter placement affects catheter success as measured by manipulation rate and quality and spread of sensory blockade.
Methods: Following IRB approval and informed consent, 240 healthy laboring parturients requesting epidural analgesia are planned for enrollment and randomization into one of two groups, 0 versus 20 mL. The epidural space will be identified with LOR to saline (2 mL) via a 17G needle. Prior to catheter insertion, either 0 or 20 mL of normal saline will be given and the plunger held for a count of 20 seconds. The primary outcome measure is epidural catheter manipulation rate, defined as any replacement or pulling back of the catheter for inadequate analgesia. Secondary outcomes include verbal analog pain scores, sensory block levels, need for boluses during labor, as well as intravenous catheter rates.
Results: To date, 34 of an anticipated 240 subjects have been enrolled. While sample sizes prohibit statistical analyses at this time, the frequency of iv catheters appears higher in the control (0 mL) compared to the intervention group (20 mL) (see Figure). In addition, sensory blockade may extend to a higher dermatomal level and be more evenly distributed in the intervention group at 15 minutes.
Discussion: Data collection is ongoing and will permit inferential analyses of primary and secondary outcomes. Early frequency results are promising and suggest that 20 mL of epidural saline predistention may prevent complications of iv catheters and uneven sensory blockade while speeding onset of block to T10 dermatomal levels.
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