Factors associated with prolonged duration of ultrasound-guided brachial plexus block for the upper limb fracture surgery: a cross-sectional study

BACKGROUND: Previous studies of factors associated with prolonged duration of ultrasound-guided brachial plexus block have included multiple surgical procedures or multiple anesthetic approaches, all of which are important confounders, and there is no study based on a single method of anesthesia exploring the factors affecting the resolution of brachial plexus block during upper limb surgery, especially in Asians. This study aimed to identify the risk factors affecting the prolonged duration of US-guided brachial plexus block in American Society of Anesthesiologists (ASA) I–II grade patients to improve postoperative analgesia. METHODS: This study enrolled patients scheduled to undergo surgery for upper limb fracture in Anting Hospital, Shanghai from May 2021 to September 2021. Inclusion criteria: (I) patients aged 18 years and above; (II) ASA I–II grade patients; (III) success of US-guided brachial plexus block. Based on the median duration of brachial plexus block, patients were divided into a <5-hour group and a ≥5-hour group. The factors were selected base on previous studies conclution and clinical demographic characteristics of patients. Multivariable logistic regression was used to estimate relevant influencing factors. RESULTS: A total of 129 patients (51.2% males; 51.01±16.54 years old) were analyzed. The duration of brachial plexus block was 2–12 hours, with a median duration of 5.09 hours. Multivariable analysis suggested that age 40–49 years [odds ratio (OR): 4.841; 95% confidence interval (CI): 1.033 to 22.695; P=0.045], 50–59 years (OR: 4.730, 95% CI: 1.149 to 19.474; P=0.031), 60 years (OR: 8.540; 95% CI: 1.605 to 45.449; P=0.012), gender (OR: 3.314; 95% CI: 1.330 to 8.257; P=0.010), alanine aminotransferase (ALT; OR: 5.817, 95% CI: 1.509 to 22.472; P=0.011), and glomerular filtration rate (GFR) <60 (OR: 22.700; 95% CI: 1.994 to 198.386; P=0.012) were the risk factors for the duration of brachial plexus block. CONCLUSIONS: It is advisable to use the lowest effective dose for the shortest possible time when using ropivacaine in upper limb fracture surgery patients with elevated ALT (≥40 U/L) and lower GFR (<60 mL/min) in male patients aged ≥60 years.