Research and optimization of hydrogen addition and EGR on the combustion, performance, and emission of the biodiesel-hydrogen dual-fuel engine with different loads based on the RSM.

Pollutants produced by engines are a significant source of environmental pollution, so the study of engine emissions is very important. In this study, with CONVERGE software, a diesel engine model of the engine was produced. To better obtain the characteristic results of the engine, this was coupled with an improved chemical kinetics mechanism. Then, the results of this model were verified experimentally. Additionally, the effects of four different EGR rates on the combustion, performance, and emissions of a dual-fuel diesel engine were investigated by the verified model under different (50 %, 75 %, and 100 %) load conditions. Lastly, the brake specific fuel consumption, NOx emission, and HC emission were optimized by the response surface methodology (RSM). The results show that the pressure, temperature, and NOx emission in the engine's cylinder can all be reduced by raising the EGR at three different loads. Besides, the optimization results show that the engine achieves the best operating conditions at 100 % load, hydrogen fraction of 6.92 %, and EGR rate of 7.68 %.

Epidural Filling with Crystal-colloid Solution for Post Accidental Dural Puncture Headache: A Case Series.

PURPOSE: Post dural puncture headache (PDPH) is a common anesthetic complication caused by expected spinal puncture or accidental dural puncture during intraspinal anesthesia operation. The purpose of this study was to retrospectively analyze the clinical features and outcomes of parturients with accidental dural punctures (ADP). METHODS: (All cesarean sections at the Chongqing Health Center for Women and Children (Chongqing, China) carried out under neuraxial anesthesia from January 1, 2017 to December 31, 2018 were reviewed and data from 20 parturients with ADP were collected and analyzed. RESULTS: Seventeen individuals received crystal-colloid solution fillers and three did not. The median epidural catheter retaining time was 40 hours; the median frequency of epidural filling was three times, with a median total volume of 60 ml. One patient developed tinnitus and three complained of head swelling during filling. The median bed-stay duration was 73 hours, with total intravenous infusion volume of 7.3 L in the first three postoperative days. Two patients complained of slight dizziness and mitigation, and five felt weak. One individual had intermittent headaches and dizziness till the seventh postoperative day. CONCLUSIONS: Epidural injection of crystal-colloid solution, combined with hydration, maybe a useful preven-tive strategy for ADP-induced headache after cesarean section.

ED50 of propofol in combination with low-dose sufentanil for intravenous anaesthesia in hysteroscopy.

OBJECTIVES: Sufentanil has favourable pharmacodynamic and pharmacokinetic properties as an opioid, and it is usually co-administered with propofol as intravenous anaesthesia for hysteroscopic examination or therapeutic surgery. However, the optimal dosage of propofol when it is co-administered with low-dose sufentanil has not yet been established. This study was designed to find the median effective dose of propofol for intravenous anaesthesia when combined with low-dose sufentanil. METHODS: Fifty-four patients were enrolled and randomized into two groups in this prospective study. Sufentanil 0.2 µg/kg (Group A) or 0.1 µg/kg (Group B) was given intravenously before speculum placement. The initial propofol dose was set at 2 mg/kg and varied by 0.1 mg/kg according to the sequential allocation up-and-down rule designed by Dixon and Massey. Respiratory depression, duration of initial dose of propofol, total drug quantity administered and recovery time were recorded. RESULTS: The ED50 of propofol was 1.651 mg/kg (95% CI, 1.561-1.722 mg/kg) in Group A and 1.991 mg/kg (95% CI, 1.902-2.081 mg/kg) in Group B. The ED95 of propofol was 1.827 mg/kg (95% CI, 1.746-2.236 mg/kg) in Group A and 2.153 mg/kg (95% CI, 2.070-2.73 7 mg/kg) in Group B. The initial and total dosage of propofol in Group A were significantly lower than those in Group B, but the incidence of respiratory depression in Group A (26.67%) was significantly higher than that in Group B (4.17%). CONCLUSION: The ED50 values for propofol when co-administered with low-dose sufentanil for intravenous anaesthesia in hysteroscopy were 1.651 mg/kg (sufentanil 0.2 µg/kg) and 1.991 mg/kg (sufentanil 0.1 µg/kg). (www.chictr.org.cn, registration number: ChiCTR1900021224).