Novel sulfonated poly (vinyl alcohol)/carboxy methyl cellulose/acrylamide-based hybrid polyelectrolyte membranes.

Novel polyelectrolytic hybrid membranes are prepared by blending carboxy methyl cellulose (CMC)-polyvinyl alcohol (PVA)-acrylamide (AA). Succinic acid and chlorosulfonic acid (CSA) are employed as crosslinkers and modifiers, respectively. Additionally, carboxylated carbon nanotube (CCNT) and sulfonated activated carbon (SAC) as fillers are used to attain appropriate chemical and mechanical stability for use as polyelectrolyte membranes (PEM). CMC, PVA, and AA are mixed and treated with CSA, CCNT, and SAC in different concentrations. First, CMC/PVA/AA solution is modified using CSA to produce a sulfonated polymeric matrix. Second, a different amount of CCNT or SAC was added as a filler to enhance the ion exchange capacity (IEC), ionic conductivity, and chemical stability. Third, the solution is cast as polyelectrolytic membranes. Chemical interactions between CMC, PVA, AA and other membrane components were confirmed using various characterization techniques such as Raman scattering spectroscopy and Fourier Transform Infrared (FTIR). Furthermore, mechanical strength, methanol uptake, gel fraction, ion exchange capacity (IEC), proton conductivity (PC), chemical and thermal stability were determined as functions of varied membrane modification components. Results reveal that the increase of CSA, CCNT and SAC is leading to increase the IEC values reaching 1.54 mmol/g for (CMC/PVA-4% CSA), 1.74 mmol/g for (CMC/PVA-4%CSA-2%CCNT) and 2.31 mmol/g for (CMC/PVA-4% CSA-2% SAC) comparing to 0.11 mmol/g for non-modified CMC/PVA/AA membrane. Sequentially, the proton conductivity value is changed from 1 × 10-3 S/cm in non-modified CMC/PVA/AA membrane to 0.082 S/cm for (CMC/PVA-4% CSA), 0.0984 S/cm for (CMC/PVA-4%CSA-2%CCNT) and 0.1050 S/cm for (CMC/PVA-4% CSA-2% SAC). Such results enhance the potential feasibility of modified CMC/PVA/AA hybrid as polyelectrolytic membranes.

Heart Rate Variability as A Predictor of Hypotension Following Spinal Anesthesia for Elective Caesarian Section in Preeclamptic Parturients: A Descriptive Observational Study.

AIM: In this study we aimed to find out the heart rate variability measuring using electrical cardiometry is not reliable as a predictor for hypotension following spinal anesthesia in preeclamptic parturients undergoing elective cesarean section. METHODS: Electrical Cardiometry system was used to measure Heart rate variability (HRV) at five different time points before fluid loading (T0, baseline), after fluid loading (T1), 5 min after spinal anaesthesia (T2), 15 min after spinal anaesthesia (T3) and 30 min after spinal anaesthesia (T4). Traditional HRV measurement was determined using time-domain analysis. This Observational descriptive cohort study was conducted in Kasr Al-Ainy Hospital, Faculty of Medicine, Cairo University from February 2018 till June 2019, after approval of the Ethical Committee and written patients consent. RESULTS: The main finding of the current study is that heart rate variability measuring using electrical cardiometry is not reliable as a predictor for hypotension following spinal anaesthesia in preeclamptic parturients undergoing elective cesarean section. CONCLUSION: Heart rate variability cannot be used as a predictor for hypotension following spinal anaesthesia in preeclamptic patients undergoing elective caesarean section using electrical cardiometry.