Pain threshold, anxiety and other factors affect intensity of postoperative pain in gastric cancer patients: A prospective cohort study

Objective: This prospective cohort study explored factors related to postoperative pain in gastric cancer patients.Methods: A total of 236 patients who underwent gastrectomy were enrolled. All patients enrolled in the study completed the Hospital Anxiety and Depression Scale(HADS) questionnaire and Life Orientation Test-Revised(LOT-R) questionnaire on the day before surgery. Heat pain threshold(HPT), cold pain threshold(CPT) and pressure pain threshold(PPT) were measured for all patients one day prior to surgery and demographic details were collected. All patients were connected to a patient-controlled intravenous analgesia(PCIA) pump at the end of the surgery. The occurrence of postoperative pain was used as a dependent variable, and multivariate logistic regression analyses were conducted to screen for factors affecting postoperative pain.Results: In total, 83 patients(35.2%) had postoperative pain. Body mass index(BMI) ≥28 kg/m^(2) [odds ratio(OR): 2.67;95% confidence interval(95% CI): 1.07-6.67], total gastrectomy(OR: 2.64;95% CI: 1.42-4.91),preoperative anxiety score ≥8(OR: 2.37;95% CI: 1.12-5.02), heat pain threshold ≤4.9 s(OR: 2.14;95% CI:1.06-4.32), pressure pain threshold ≤4 g(OR: 2.05;95% CI: 1.05-4.03), and female gender(OR: 1.99;95% CI:1.04-3.83) were risk factors for postoperative pain.Conclusions: Obesity, wide range of gastrectomy, high preoperative anxiety, low HPT and PPT, and female gender are associated with increased risk for postoperative pain.

Design of hollow core step-index antiresonant fiber with stepped refractive indices cladding

With the benefits of low latency,wide transmission bandwidth,and large mode field area,hollow-core antiresonant fiber(HC-ARF)has been a research hotspot in the past decade.In this paper,a hollow core step-index antiresonant fiber(HC-SARF),with stepped refractive indices cladding,is proposed and numerically demonstrated with the benefits of loss reduction and bending improvement.Glass-based capil-laries with both high(n=1.45)and low(as low as n=1.36)refractive indices layers are introduced and formatted in the cladding air holes.Using the finite element method to perform numerical analysis of the designed fiber,results show that at the laser wavelengths of 980 and 1064 nm,the confinement loss is favorably reduced by about 6 dB/km compared with the conventional uniform cladding HC-ARF.The bending loss,around 15 cm bending radius of this fiber,is also reduced by 2 dB/km.The cladding air hole radius in this fiber is further investigated to optimize the confinement loss and the mode field diameter with single-mode transmission behavior.This proposed HC-SARF has great potential in optical fiber transmission and high energy delivery.