Background and Goal of Study: Neuraxial analgesia depends on the correct placement of the needle. Optimal technique for localizing the epidural space has not been described, so anesthesiologists usually choose whether to use air or saline for loss of resistance based on personal experience. This study compares loss of resistance of the epidural space using air and saline ≤ 3 mL.

Materials and Methods: This randomized clinical trial included pregnant to term women between the ages of 18 and 40. Patients were assigned to the groups of loss of resistance with either air or saline in a 1:1 proportion. Items evaluated were the correct placement of the catheter, pain control, maternal satisfaction, block characteristics and adverse effects.

Results and Discussion: 208 patients were included. No statistically significant differences were found regarding successful identification of the epidural space (p=0.56). Pain control, maternal satisfaction, block characteristics and incidence of adverse effects were similar for both groups. Time to insertion of the epidural catheter was not taken into account, which may have affected the results; because a long procedure may influence the quality of analgesia and patient satisfaction.

Conclusion: No statistically significant differences were found regarding pain and obstetric outcomes. Neither technique showed an increased occurrence of complications.   

09 / Epidural analgesia: a randomized clinical trial comparing loss of resistance to saline versus low volume of air