Comparison of compound A concentrations with sevoflurane anaesthesia using a closed system with a PhysioFlex anaesthesia machine vs a low-flow system with a conventional anaesthesia machine

Sevoflurane anaesthesia was conducted using a totally closed circuit PhysioFlex anaesthesia machine (PhysioFlex group) or with a standard Modulus CD anaesthesia machine (Modulus group) (n = 8 in each group). The PhysioFlex was used under closed system conditions and the Modulus was used under low-flow system conditions (flow rate 1 litre min-1). Concentrations of sevoflurane degradation products and the temperature of soda lime were compared. Degradation products in the circuit were measured hourly, and the temperature of soda lime was monitored. The only degradation product detected was CF2 = C(CF3)-O-CH2F (compound A). Maximum concentrations of compound A were significantly lower (median 8.5 (range 5.4-15.9) ppm) in the PhysioFlex than in the Modulus group (21.2 (16.5-27.4) ppm) (P < 0.05). The maximum temperature of soda lime was also significantly lower in the PhysioFlex group (35.3 (32.1-36.3) degrees C vs 44.6 (43.0-47.1) degrees C, respectively) (P < 0.05). Hourly compound A concentrations were lower in the PhysioFlex group than in the Modulus group. End-tidal sevoflurane concentrations during measurement of degradation products were not different between groups. Therefore, use of the totally closed PhysioFlex system may significantly reduce compound A concentrations compared with low-flow anaesthesia using a standard anaesthesia machine.      

Intraoperative autotransfusion with a new disposable system

In the past 2 years we have used a simple, disposable set for Intraoperative autotransfusion. The system consists of a rigid plastic case with a flexible bag inside constituting a 600 ml reservoir which can be connected to any suitable vacuum source. We used it so far in 56 patients undergoing various vascular operations who were autotransfused a total of about 160 units of blood without any complications with regard to blood coagulation or hemolysis.     

Optimal control of a production system with periodic maintenance

In this paper we consider a production system consisting of one machine for which maintenance is performed on a periodic basis. When the machine is undergoing maintenance, the system is shut down and cannot produce. One part-type is produced and the demand rate is assumed to be constant. In order to make on-time delivery, the objective is to produce following the demand as closely as possible. However, the maintenance disruptions make the production deviate from the demand. We formulate the production flow control problem as an optimal control model and use Pontryagin's minimum principle to solve the special case of one up-down cycle. We then solve the general N-cycle problem based on the one-cycle solution.     

Fixation of a periprosthetic humeral fracture with CCG-cable system

We report a case of periprosthetic fracture of the shoulder, treated operatively. A special plate/cable system (ECG) was used with an excellent outcome. This easy technique is recommended for such fractures.     

A circle system with a rotating wick vaporizer

The humidity output of a circle system was raised to 28 mgH₂O/l by the use of a modified rotating wick vaporizer placed in the center of the soda lime canister and coaxial inspiratory and expiratory limbs. Both the fresh gas inflow and the expired gases passed through the lime and reached a compartment below it. The bag/ventilator connector, bearing a pressure relief valve, opened on the lateral wall of that compartment. Gases returning to the inspiratory valve passed: (1) through a tube in the canister connecting the inferior compartment to the vaporizer above water level, (2) through the upper portion of the vaporizer and around the rotating wick, and (3) through a tube emerging from the top of the vaporizer to reach the inspiratory valve. Thus inspired gases were humidified by the rotating wick constantly replenishing its water content warmed by the reaction of neutralization. The use of coaxial inspiratory and expiratory limbs reduced water condensation outside the canister.     

Experience with a programmable valve shunt system.

OBJECT: The goal of this study was to clarify the efficacy of the Codman Hakim programmable valve. Clinical data obtained in 179 patients with hydrocephalus or other intracranial fluid-accumulating diseases were analyzed. METHODS: Shunt placement operations were effective in 168 patients, approximately one half (50.6%) of whose devices required reprogramming of opening pressure postoperatively. This was a significantly larger number of shunts than the authors had thought would need reprogramming. Extremely narrowed ventricles observed on computerized tomography scans, as well as clinical symptoms related to inadequate or excessive cerebrospinal fluid drainage, improved in patients after shunt reprogramming. Shunt reprogramming frequently was necessary in patients with posthemorrhagic acute hydrocephalus; the programmable valve proved particularly beneficial for such patients. Subdural effusion and arachnoid cyst also proved to be good indications for use of the valve. Twelve patients (7%) suffered complications postoperatively. The most common complication was valve obstruction, which occurred in five patients, most of whom had brain tumors. CONCLUSIONS: The programmable valve was beneficial for the treatment of hydrocephalus and other intracranial fluid-accumulating diseases. It is important to be careful in selecting patients for treatment with the programmable valve, because complications involving the valve seem more likely in brain tumor cases. The valve proved to be poorly resistant to magnetic fields; therefore, it is essential to confirm opening pressure after every magnetic resonance imaging examination. The authors recommend that an identification system for patients be developed so that medical personnel will be aware of the presence of the valve and the previous setting of opening pressure.     

3D腹腔镜胃癌根治术

胃癌在中国是发病率最高的恶性肿瘤之一。但是,由于腹腔镜胃癌手术解剖层面多、淋巴清扫范围广泛、消化道重建多样,故在普外科领域腹腔镜下胃癌根治术为难度较高的手术。随着科技与设备的发展,3D腹腔镜逐步踏入普外科手术领域,提供了三维立体图像,使手术变得更加精细,降低操作难度,弥补了传统2D腹腔镜缺乏纵深感、立体解剖描述不足的劣势。立体视野能为主刀提供更加清晰的手术视野,协助术者完成精细操作,在胃癌根治术中使淋巴清扫、系膜解剖等变得更加流畅、精准。     

Ambulatory pH: monitoring with a wireless system

Background Currently, pH monitoring is the gold standard for assessing esophageal acid exposure in patients with gastroesophageal reflux disease (GERD). The shortcomings of 24-h pH-monitoring wires led to the development of a 48-h, catheter-free pH measurement system using the telemetry technique with the BRAVO capsule. This prospective study aimed to compare conventional 24-h pH monitoring with the BRAVO catheter-free pH-monitoring system in patients with GERD, patients after antireflux surgery, and a healthy control group. Methods A sample of 133 participants were enrolled in the current trial and divided into three subgroups. Group 1 consisted of 10 healthy volunteers. Group 2 consisted of 123 patients with symptomatic gastroesophageal reflux and endoscopic signs of esophagitis. Group 3 consisted of 43 GERD patients (extracted from group 2) who underwent a laparoscopic 360° “floppy” Nissen fundoplication. All the patients underwent both conventional 24-h pH monitoring and BRAVO catheter-free pH monitoring. The data for both methods were recorded and compared in line with the different patient groups regarding their validity and reliability. Additionally, all the patients were interviewed with a standardized questionnaire concerning their subjective perception of the two different methods. Results Both the 24-h pH monitoring and the 48-h BRAVO catheter-free pH monitoring could be successfully performed for all the patients. During measurement, 122 of the patients (92%) continued working or performing daily activities. A significant difference could not be found regarding objective outcome between the two measurement methods in the three patient groups. The two methods showed comparable results in terms of data and measurement reliability. The validity also was comparable, with no significant differences within the groups. Concerning the patients’ subjective estimation of the two methods, the patients reported reduced regular activities and a higher level of discomfort during measurement with the conventional 24-h pH-monitoring system (p < 0.001 and p< 0.0001, respectively). Conclusion Both conventional 24-h pH monitoring and the 48-h catheter-free pH monitoring are valid and reliable recording devices for measuring esophageal acid exposure. However, from the patients’ point of view, the BRAVO capsule affords less discomfort in the throat and allows more normal daily activities.     

Optimal maintenance of a system of machines with weakest-link-dependent performance

This paper considers the maintenance policy of a system of machines whose deterioration is dependent on the machines' quality states and maintenance efforts. The return of the system of machines, however, is dependent only on the machine with the lowest quality state. This becomes a realistic feature when the machines are arranged in series as part of an assembly line production. This feature also gives rise to an unconventional optimization problem with an interesting theoretical challenge. The problem is subsequently formulated as a constrained optimal control problem. It is first shown that the problem admits an optimal control. Then, by using the control parametrization approach, an efficient computational scheme is devised for solving the problem.     

Totally endoscopic Nissen fundoplication with a robotic system in a child

The Da Vinci robot device represents the latest advance in laparoendoscopic surgery. We report the case of an endoscopic Nissen fundoplication performed with the aid of a telemanipulation robot system in a 10-year-old girl. To our knowledge, this is the first such case to be reported. In addition to standard monitoring, we used invasive blood pressure monitoring during the 282-min period of general anesthesia. Arterial blood gas samples were analyzed at short intervals. During surgery, which included a 172-min period of intraperitoneal insufflation of carbon dioxide (CO2), no significant changes were observed in PH, arterial oxygen pressure (PaO2), arterial carbon dioxide pressure (PaCO2), heart rate, or mean arterial pressure. Body temperature was maintained with an external warming blanket. Total intravenous anesthesia with continously administered propofol, remifentanil, and mivacurium for continous muscle relaxation allowed extubation immediately after skin closure. The girl was discharged from hospital on postoperative day 6. Robot-assisted techniques have the potential to significantly improve the performance of laparoendoscopic surgery. However, despite our encouraging first results, the potential risks of robot-assisted surgery have not yet been definitively established. Therefore, patients submitted to this type of procedure require intensive and even invasive monitoring.