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Background: Laparoscopic surgery is associated with a remark-ably high risk of post-operative nausea and vomiting. The reasons for this high rate of PONV include mechanical factors (such as pressure on the stomach and gut caused by the pneumoperitoneum), neural factors (such as vagal reflexes elicited by irritation of parasympathetic nerve endings in the abdomen), and chemical factors (which include speculative considerations regarding a possible influence of CO2 on PONV). Objective: To compare the effect of midazolam, ondansetron or dexamethasone on prophylaxis against PONV in patients undergoing laparoscopic abdominal surgeries. Patients and Methods: After approval of anesthesiology department, scientific and ethical committees in Ain Shams University Hospitals, patients were included in the study, and were divided into three groups (n = 40; each); group M (midazolam group) and Group O (ondansetron group) and group D (dexamethasone group). Results: The three groups were adequately monitored and assessed post-operatively and they were compared regarding post-operative nausea and vomiting outcome by recording the incidence of nausea and vomiting and recording the call for rescue antiemetic. Demographic data, intra-operative hemodynamics and post-operative pain score, occurrence of side effects, sedation score and patient satisfaction scores were also assessed, we found about 95% of (M) group achieve the complete response, that mean midazolam provided PONV prophylaxis comparable to dexamethasone and ondansetron in patients who underwent laparoscopic abdominal surgeries. Conclusion: From this study, we can conclude that the midazolam is as effective as ondansetron and dexamethasone in reducing the incidence of nausea and vomiting in post-operative period of laparoscopic abdominal surgeries. [ABSTRACT FROM AUTHOR]

The augmentation of the Global Navigation Satellite System (GNSS) by Low Earth Orbit (LEO) satellites is proposed as an effective method to improve the precision and shorten the convergence time of Precise Point Positioning (PPP). Serving as navigation satellites in the future, LEO satellites need to be provided with their high-accuracy orbits in real-time. This would potentially enable the high-accuracy real-time LEO satellite clock determination, and eventually facilitate the high-accuracy ground-based positioning. Studies have been performed to achieve such real-time orbits using a Kalman filter in both the kinematic and reduced-dynamic modes. Batch Least-Squares (BLS) adjustment delivers more stable orbits in near-real-time, as it performs better phase screening. However, it suffers from longer delays compared to the Kalman filter. With the LEO satellite orbit prediction strategies improved over time, this latency can be bridged by short-term orbit prediction. In this study, using real-time GNSS satellite products, the real-time LEO satellite orbits are obtained based on the batch least-squares adjustment and short-term prediction. LEO ephemeris parameters are generated within specific prediction time windows. Using real data from the 500 km GRACE C satellite and 810 km Sentinel-3B satellite, the near-real-time BLS Precise Orbit Determination (POD) results exhibit good accuracy with an Orbital User Range Error (OURE) of 2–4 cm using different real-time GNSS products. A range of delays of the BLS POD processes are assumed, based on tests performed on different processing machines, leading to various prediction windows, from 3–8 min to 12–17 min that correspond to the real-time usage. The orbital prediction errors are shown to be highly correlated with the orbital height and the prediction time. The computational efficiency thus becomes essential to reduce the prediction errors for a certain LEO satellite. For advanced processing units leading to a prediction window shorter or equal to 6–11 min, one can expect a total real-time orbital error budget of 3–5 cm, provided that an appropriate prediction strategy is applied and high-quality GNSS products are used. For a given fitting interval, the ephemeris fitting errors are generally related to the number of ephemeris parameters and the orbital height. Compared with the prediction errors, the ephemeris fitting errors do not play a significant role in the total error budget when using 22 ephemeris parameters. [ABSTRACT FROM AUTHOR]