Kim JH, et al. J Korean Med Sci. 2023 Feb;38(8):e64. https://doi.org/10.3346/jkms.2023.38.e64

Objective: To assess the efficacy and safety of perioperative melatonin and melatonin agonists in preventing postoperative delirium (POD). Methods: We conducted a systematic search for randomized controlled trials (RCTs) published through December 2022. The primary outcome was efficacy based on the incidence of POD (POD-I). Secondary outcomes included efficacy and safety according to the length of hospital or intensive care unit stay, in-hospital mortality, and adverse events. Subgroup analyses of POD-I were based on the type and dose of drug (low- and high-dose melatonin, ramelteon), the postoperative period (early or late), and the type of surgery. Results: In the analysis (16 RCTs, 1981 patients), POD-I was lower in the treatment group than in the control group (risk ratio [RR] = 0.57). POD-I was lower in the high-dose melatonin group than in the control group (RR = 0.41), whereas no benefit was observed in the low-dose melatonin and ramelteon groups. POD-I was lower in the melatonin group in the early postoperative period (RR = 0.35) and in patients undergoing cardiopulmonary surgery (RR = 0.54). Conclusion: Perioperative melatonin or melatonin agonist treatment suppressed POD without severe adverse events, particularly at higher doses, during the early postoperative period, and after cardiopulmonary surgery.

Background and Objective: There are a growing number of porcine models being used for orthopaedic experiments for human beings. Therefore, pain management of those research pigs using ultrasound (US)‐guided nerve block can be usefully performed. The aim of this study is to determine optimal US approaches for accessing and localizing the sciatic nerve at the midthigh level, a relevant block site for hindlimb surgery in female Yorkshire pigs.Methods: As a first step, we dissected the intubated, blood‐washed out pigs (n = 3) and confirmed the anatomical position of the sciatic nerve at midthigh level. After dissection, we found the sciatic nerve, connected with nerve stimulator, and checked the dorsiflexion or plantar flexion of the hindlimb. We matched the sciatic nerve location with the US image. After the pigs were euthanized, the neural structures of the sciatic nerve were confirmed by histological examination with H&E staining. In second step, a main US‐guided sciatic nerve block study was done in the intubated, live pigs (n = 8) based on the above study.Results: In lateral position, the effective US‐guided nerve block site was about 6 cm from the patella crease level; immediately proximal to the bifurcation of the sciatic nerve into the tibial nerve and common peroneal nerve. The distal femur was selected as the landmark. There were no vessels or other nerves surrounding the sciatic nerve. The needle‐tip was positioned less than 1 cm lateral from the distal femur and about 2 cm deep to skin. ‘Donut sign’ in US images was confirmed in all 16 nerves.Conclusions: Midthigh level sciatic nerve is located superficially, which enables nerve block to be easily performed using US. This is the first study to describe midthigh sciatic nerve block in the lateral position under US guidance in a porcine model from a clinical perspective.

This study uses machine learning and population data to analyze major determinants of blood transfusion among patients with hip arthroplasty. Retrospective cohort data came from Korea National Health Insurance Service claims data for 19,110 patients aged 65 years or more with hip arthroplasty in 2019. The dependent variable was blood transfusion (yes vs no) in 2019 and its 31 predictors were included. Random forest variable importance and Shapley Additive Explanations were used for identifying major predictors and the directions of their associations with blood transfusion. The random forest registered the area under the curve of 73.6%. Based on random forest variable importance, the top-10 predictors were anemia (0.25), tranexamic acid (0.17), age (0.16), socioeconomic status (0.05), spinal anesthesia (0.05), general anesthesia (0.04), sex (female) (0.04), dementia (0.03), iron (0.02), and congestive heart failure (0.02). These predictors were followed by their top-20 counterparts including cardiovascular disease, statin, chronic obstructive pulmonary disease, diabetes mellitus, chronic kidney disease, peripheral vascular disease, liver disease, solid tumor, myocardial infarction and hypertension. In terms of max Shapley Additive Explanations values, these associations were positive, e.g., anemia (0.09), tranexamic acid (0.07), age (0.09), socioeconomic status (0.05), spinal anesthesia (0.05), general anesthesia (0.04), sex (female) (0.02), dementia (0.03), iron (0.04), and congestive heart failure (0.03). For example, the inclusion of anemia, age, tranexamic acid or spinal anesthesia into the random forest will increase the probability of blood transfusion among patients with hip arthroplasty by 9%, 7%, 9% or 5%. Machine learning is an effective prediction model for blood transfusion among patients with hip arthroplasty. The high-risk group with anemia, age and comorbid conditions need to be treated with tranexamic acid, iron and/or other appropriate interventions.