• Mengzhu Li, Xiu Ni, Zhendong Xu, Fuyi Shen, Yingcai Song, Qian Li, and Zhiqiang Liu.
• From the Department of Anesthesiology, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China.
• Anesth. Analg. 2019 Jul 1; 129 (1): 155-161.

BackgroundSpinal anesthesia, which is commonly used in cesarean deliveries, is often difficult to perform in obese parturients because of poorly palpable surface landmarks and positioning challenges. This study aimed to evaluate the benefits of ultrasound-assisted technology for performing spinal anesthesia in obese parturients.MethodsParturients with a body mass index (BMI) ≥30 kg/m scheduled for elective cesarean delivery were randomized to undergo spinal anesthesia using the conventional landmark location technique (landmark group, n = 40) or prepuncture ultrasound examination (ultrasound group, n = 40). All participants underwent spinal anesthesia in the lateral position. The primary outcome was the first-attempt success rate. Secondary outcomes were the number of skin punctures and needle passes, procedure times, patient satisfaction, changes in the intended interspace, and incidence of complications.ResultsThe ultrasound group had a significantly higher first-attempt success rate (87.5% vs 52.5%; P = .001), fewer cases requiring >10 needle passes (1 vs 17; P < .001), and fewer skin punctures and needle passes (P < .001 for both). There was no statistically significant difference in the time taken to identify the needle insertion site between the 2 groups (202.5 vs 272.0 seconds; P = .580). Both the spinal injection time and total procedure time were significantly longer in the landmark group (P < .001). Patient satisfaction scores were significantly higher in the ultrasound group (P = .001). Among patients with BMI between 30 and 34.9 kg/m, there was no statistically significant difference in the first-attempt success rate (P = .407), number of cases with >10 needle passes (P = .231), spinal injection time (P = .081), or total procedure time (P = .729); however, more time was required to identify the needle insertion site in the ultrasound group (P < .001). For patients with BMI between 35 and 43 kg/m, the ultrasound group had a significantly higher first-attempt success rate (P ≤ .041), fewer cases with >10 needle passes (P ≤ .01), and shorter procedure times, including the time required to identify the needle insertion site (P < .001).ConclusionsPrepuncture ultrasound examination can facilitate spinal anesthesia in the lateral position in obese parturients (35 kg/m ≤ BMI ≤ 43 kg/m) by improving the first-attempt success rate, reducing the number of needle passes and puncture attempts, shortening the total procedure time, and improving patient satisfaction.

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