Experimental and Numerical Study of a Thermal Expansion Gyroscope for Different Gases.

A new single-axis gas thermal gyroscope without proof mass is presented in this paper. The device was designed, manufactured and experimentally characterized. The obtained results were compared to numerical simulation. The working principle of the gyroscope is based on the deflection of a laminar gas flow caused by the Coriolis effect. A bidirectional hot air flow is generated by alternating activation of two suspended resistive micro-heaters. The heated gas is encapsulated in a semi-open cavity and the gas expands primarily inside the cavity. The thermal expansion gyroscope has a simple structure. Indeed, the device is composed of a micromachined cavity on which three bridges are suspended. The central bridge is electrically separated into two segments enabling to set up two heaters which may be supplied independently from each other. The two other bridges, placed symmetrically on each side of the central bridge, are equipped with temperature detectors which measure variations in gas temperature. The differential temperature depends on the rotational velocity applied to the system. Various parameters such as the heating duty cycle, the type of the gas and the power injected into the heaters have been studied to define the optimal working conditions required to obtain the highest level of sensitivity over a measurement range of around 1000°/s. The robustness of the device has also been tested and validated for a shock resistance of 10,000 g for a duration of 400 µs.

Overview of colorectal resections in a reference center in Curitiba - Brazil: experience with open and laparoscopic approach / Aspectos gerais da ressecção colorretal em centro de referência em Curitiba, Brasil: experiência com abordagens laparoscópica e a céu aberto

ABSTRACT Introduction: Minimally invasive approach has become the preferential option for the treatment of surgical diseases of the Gastrointestinal Tract, due to its numerous advantages. However, in the Colorectal Surgery field, the acceptance of videolaparoscopy was slower. For example, an American study showed that the percentage of laparoscopic cholecystectomy increased from 2.5% in 1988 to 73.7% in 1992, the rate of laparoscopic sigmoidectomy increased from 4.3% in 2000 to only 7.6% in 2004. Objecties: Our goal was to compare several variables between patients submitted to colorectal resections performed through open surgery or videolaparoscopy. Methods: This is a retrospective observational study performed in a Teaching Private Hospital of the City of Curitiba, Brazil, with the revision of 395 medical charts of patients subjected to colorectal resections from January 2011 through June 2016. Results: 349 patients were included in the study. 243 (69.6%) were subjected to laparoscopic colon resection (LCR) and 106 (30.4%) to open colon resection (OCR). Mean age was 62.2 years for patients undergoing LCR and 68.8 year for OCR (p = 0.0082). Among emergency procedures, 92.5% consisted of OCR and 7.5% were LCRs. Surgery duration was similar in both types of access (196 min in OCR versus 195 min in LCR; p = 0.9864). Diet introduction was earlier in laparoscopic surgery and anastomotic fistula rate was similar in both groups (OCR 7.5% and LCR 6.58%; p = 0.7438). Hospital stay was shorter in patients undergoing laparoscopic resections (7.53 ± 7.3 days) than in the ones undergoing open surgery (17.2 ± 19.3) (p < 0.001). In the OCR group, 70 patients needed ICU admission (66%), and stayed a mean of 12.3 days under intensive care. In the LCR group, however, only 30 needed ICU (12.3%), and the ones who needed it stayed a mean of 5.6 days (p < 0.001). Conclusions Videolaparoscopic approach is a safe and effective option in the treatment of colorectal diseases. Surgery duration and anastomotic fistula rates are similar to the open resections. Hospital stay and ICU stay durations, however, were shorter in patients submitted to laparoscopic colectomies.

RESUMO Introdução: Abordagens minimamente invasivas passaram a ser a opção preferencial para tratamento de doenças cirúrgicas do trato gastrointestinal, graças às suas numerosas vantagens. Contudo, no campo da cirurgia colorretal, a aceitação da videolaparoscopia foi mais lenta. Exemplificando, um estudo norte-americano demonstrou que o percentual de colecistectomias laparoscópicas aumentou de 2,5% em 1988 para 73,7% em 1992, enquanto que o percentual de sigmoidectomias laparoscópicas aumentou de 4,3% em 2000 para somente 7,6% em 2004. Objetivos: Nosso objetivo foi comparar diversas variáveis entre pacientes submetidos a ressecções colorretais realizadas por cirurgia a céu aberto, ou por videolaparoscopia. Métodos: Este é um estudo observacional retrospectivo realizado em um Hospital-Escola privado em Curitiba, Brasil, com revisão de 395 prontuários clínicos de pacientes submetidos a ressecções colorretais de janeiro de 2011 até junho de 2016. Resultados: 349 pacientes foram incluídos no estudo. 243 (69,6%) foram submetidos à ressecção laparoscópica de cólon por laparoscopia (RLC) e 106 (30,4%) foram tratados com ressecção de cólon a céu aberto (RCCA). A média de idade foi de 62,2 anos para os pacientes tratados com RLC e de 68,8 anos para RCCA (p = 0,0082). Entre os procedimentos de emergência, 92,5% dos pacientes foram tratados com RCCA e 7,5% com RLC. A duração da cirurgia foi similar para os dois tipos de acesso (196 min para RCCA versus 195 min para RLC; p = 0,9864). A introdução da alimentação ocorreu mais cedo nos pacientes tratados com a cirurgia laparoscópica, e o percentual de fístulas anastomóticas foi similar para os dois grupos (RCCA 7,5% e RLC 6,58%; p = 0,7438). A permanência no hospital foi mais curta para os pacientes tratados por ressecção laparoscópica (7,53 ± 7,3 dias) versus pacientes tratados com cirurgia a céu aberto (17,2 ± 19,3 dias) (p< 0,001). No grupo RCCA, 70 pacientes precisaram ser internados na UTI (66%), com permanência média de 12,3 dias em terapia intensiva. Mas no grupo RLC, apenas 30 pacientes necessitaram de internação na UTI (12,3%), e sua permanência em terapia intensiva foi de, em média, 5,6 dias (p < 0,001). Conclusões: A abordagem videolaparoscópica é opção segura e efetiva no tratamento de doenças colorretais. A duração da cirurgia e os percentuais de confecção de fístula anastomótica são similares ao observado nas ressecções a céu aberto. No entanto, a permanência no hospital e o tempo de permanência na UTI foram mais curtos para os pacientes tratados com colectomia laparoscópica.

Umbilical hernia in patients with liver cirrhosis: A surgical challenge.

Umbilical hernia occurs in 20% of the patients with liver cirrhosis complicated with ascites. Due to the enormous intraabdominal pressure secondary to the ascites, umbilical hernia in these patients has a tendency to enlarge rapidly and to complicate. The treatment of umbilical hernia in these patients is a surgical challenge. Ascites control is the mainstay to reduce hernia recurrence and postoperative complications, such as wound infection, evisceration, ascites drainage, and peritonitis. Intermittent paracentesis, temporary peritoneal dialysis catheter or transjugular intrahepatic portosystemic shunt may be necessary to control ascites. Hernia repair is indicated in patients in whom medical treatment is effective in controlling ascites. Patients who have a good perspective to be transplanted within 3-6 mo, herniorrhaphy should be performed during transplantation. Hernia repair with mesh is associated with lower recurrence rate, but with higher surgical site infection when compared to hernia correction with conventional fascial suture. There is no consensus on the best abdominal wall layer in which the mesh should be placed: Onlay, sublay, or underlay. Many studies have demonstrated several advantages of the laparoscopic umbilical herniorrhaphy in cirrhotic patients compared with open surgical treatment.