Managing pain and anxiety during transabdominal chorionic villus sampling. A noninferiority randomized trial of nitrous oxide vs local anesthesia

Abstract

Introduction: Transabdominal chorionic villus sampling (CVS) is an invasive proce-dure for prenatal diagnosis reported to be associated with anxiety and pain. In this context, the need for analgesia during CVS has been considered useful. Even though several authors have been interested in pain management during amniocentesis, no study has been published on pain reduction during CVS. Our objective was to evaluate pain and anxiety management during transabdominal CVS using nitrous oxide (N 2 O) and local anesthesia. Material and methods:In a randomized controlled noninferiority trial, self-administered nitrous oxide (N 2 O) inhalation (equimolar premix of oxygen and nitrous oxide) was compared with local anesthesia (1% lidocaine) before CVS. Primary outcome was pain and secondary outcome was anxiety, both measured on a visual analog scale 30-60 minutes before, immediately after (5-10 minutes) and 30-60 minutes after CVS. With a statistical power of 90%, type I error of 5% and two-sided test and potential exclusions, a sample size of 96 patients per group was enrolled and randomized. No patient was enrolled before the trial registration date.

Efficacy of nitrous oxide in adults undergoing puncture biopsy: A systematic review and meta-analysis of randomized controlled trials

“…Among the included trials, 542 underwent experimental arm and 528 patients were in the control arm. Among the selected trials, ten [ 21 – 27 , 29 , 30 , 32 ] were conducted in Europe, one [ 31 ] in Asia, and one [ 28 ] in South America. The participants in one trial [ 30 ] were only female, three [ 22 , 23 , 28 ] were only male, and the remaining eight [ 21 , 24 – 27 , 29 , 31 , 32 ] contained males and females.…”

“…Among the selected trials, ten [ 21 – 27 , 29 , 30 , 32 ] were conducted in Europe, one [ 31 ] in Asia, and one [ 28 ] in South America. The participants in one trial [ 30 ] were only female, three [ 22 , 23 , 28 ] were only male, and the remaining eight [ 21 , 24 – 27 , 29 , 31 , 32 ] contained males and females. Two trials included three groups, of which one trial [ 22 ] included N 2 O group, air group and blank group, and the other trial [ 23 ] included N 2 O group, lidocaine group and blank group.…”

“…Two trials included three groups, of which one trial [ 22 ] included N 2 O group, air group and blank group, and the other trial [ 23 ] included N 2 O group, lidocaine group and blank group. One trial [ 30 ] compared N 2 O with 1% lidocaine in transabdominal chorionic villus sampling. One trial [ 32 ] compared N 2 O with midazolam in patients undergoing bone marrow biopsy.…”

“…The remaining eight trials [ 21 , 24 – 29 , 31 ] compared N 2 O with placebo (Oxygen in five RCTs [ 21 , 24 , 26 , 28 , 31 ] and N 2 /O 2 in three RCTs [ 25 , 27 , 29 ]. The diagnostic procedures included PLB [ 21 , 25 ], TUSPB [ 22 , 23 , 28 ], bone marrow biopsy [ 24 , 26 , 32 ], LP [ 27 , 29 ], transabdominal chorionic villus sampling [ 30 ] and endoscopic ultrasound-guided fine needle aspiration for digestive tract diseases [ 31 ]. The characteristics and outcomes of included trials were presented in Table 1 .…”

“…Randomized sequence generation was fully described in nine trials [ 21 , 22 , 24 , 26 – 31 ] and was judged to be unclear in three trials [ 23 , 25 , 32 ] as a result of not being reported. Allocation sequence concealment was adequately conducted in six trials [ 22 , 24 , 26 , 27 , 29 , 30 ] through sequentially sealed envelopes or other hiding methods and the remaining six [ 21 , 23 , 25 , 28 , 31 , 32 ] was judged to be unclear based on the available data. Blinding of participants and personnel was conducted in three RCTs [ 22 , 24 , 27 ] and was not conducted in two RCTs [ 26 , 30 ].…”