The air elimination capabilities of pressure infusion devices and fluid-warmers

Pressurised infusion devices may have only limited capability to detect and remove air during pressurised infusions. In order to assess pressure infusion systems with regard to their actual air elimination capabilities four disposable pressure infusion systems and fluid warmers were investigated: The Level 1 (L-1), Ranger (RA), Gymar (GY), and the Warmflo (WF). Different volumes of air were injected proximal to the heat exchanger and the remaining amount of air that was delivered at the end of the tubing was measured during pressurised infusions. Elimination of the injected air (100-200 ml) was superior by the RA system when compared to L-1 (p < 0.01). The GY and WF systems failed to eliminate the injected air. In conclusion, air elimination was best performed by the RA system. In terms of the risk of air embolism during pressurised infusions, improvements in air elimination of the investigated devices are still necessary.     

Accurate continuous drug delivery at low infusion rate with a novel microvolumetric infusion pump (MVIP): pump design, evaluation and comparison to the current standard

Infusion devices for continuous and precise drug administration are indispensable tools in anaesthesia and critical care medicine. Problems such as start-up delays, non-continuous flow and susceptibility to hydrostatic pressure changes at low infusion rates resulting in accidental bolus release or prolonged flow interruption are inherent to current infusion technology. In order to improve precise drug delivery, an innovative technical concept has been realised in a novel microvolumetric infusion pump (MVIP) device. The MVIP principle includes repeated filling and emptying of a non-compliant microsyringe without the use of valves. The performance of the MVIP prototype has been evaluated and compared with standard syringe infusion pump assemblies. The novel MVIP concept has thereby proven to eliminate most problems during infusion start-up, steady state flow and vertical pump displacement, and has the potential of revolutionising infusion technology and setting a new dimension in patient safety.     

The effect of meniscus compression on the biomechanical properties of repaired meniscal lesions

Introduction The objective of the present study was to investigate the influence of meniscus compression, as it occurs with weight-bearing, on the biomechanical behavior of different repair types.Materials and methods Young human meniscal tissue specimens were fitted with a single Bionx Arrow, a Innovasive Meniscal Screw, or a vertical suture (Ethibond 2–0) according to standard clinical practice. Test specimens then underwent repetitive loading with 10 N under 1 N pretension up to a maximum of 1182 cycles and were finally loaded to failure. Half of the cases in each group were additionally subjected to synchronized intermittent compression during the test. The main variables investigated were the number of cycles survived and ultimate failure load. To reduce the complexity, investigations were limited to the peripheral repair site.Results The number of cycles survived was significantly affected by compression and the type of repair. Arrows and Screws survived 311 and 52 cycles, respectively, without compression, while 983 and 1182 cycles were survived with added compression. In the suture group, no premature failure occurred either with or without compression. Both compression and the type of repair had a significant effect on the ultimate failure load. It increased about twofold in the Arrow and Screw group, while the suture group was not affected.Conclusions Compression of the meniscus can substantially increase the pullout resistance of meniscal repair implants and thus seems not to be a factor negatively influencing the stability of the repair.     

The rigid nasendoscope as a tool for difficult tracheal intubation: a manikin study

We examined the use of the 30 degrees rigid nasendoscope in aiding difficult tracheal intubations. A Cormack and Lehane grade 4 difficult intubation (no view of glottis or epiglottis) was set up on a manikin. After 10 s of tuition, 40 anaesthetists attempted to pass a standard gum elastic bougie between the cords, with and without the nasendoscope, in randomised order. A bougie curved to an 'optimal curve' was also tested. Using the standard bougie 13/40 (33%) passed the bougie between the cords without the nasendoscope, compared with 31/40 (78%) when using the nasendoscope (p < 0.001). The 'optimal curve' bougie resulted in 29/40 (73%) and 39/40 (98%) success rates without and with the nasendoscope, respectively (p = 0.004). The nasendoscope is a simple and easy to use tool in grade 4 intubation, and results are improved further by the use of an 'optimal curve' bougie.     

Re-use of equipment between patients receiving total intravenous anaesthesia: a postal survey of current practice

In order to establish current practice with regard to the reuse of infusion equipment between patients receiving total intravenous anaesthesia (TIVA), a postal survey of 393 consultants was carried out. Additionally, consultants' awareness of relevant guidelines was assessed. Overall, 46% of consultants change all equipment between cases, 37% change one-way valves and 17% change distal lengths of the infusion tubing. Only 13% of consultants reported knowledge of any guidelines. In the absence of any data relevant to the current techniques of administering TIVA, the level of risk associated with the reuse of infusion components is impossible to quantify. Disposal of all equipment between cases incurs a 26% greater cost when compared to changing one-way valves alone. Variation in practice between consultants creates the potential for system errors. Practice should be standardised and, to comply with the published guidelines, should involve disposal of all equipment between cases.     

The effect of mechanical cleaning and thermal disinfection on light intensity provided by fibrelight Macintosh laryngoscopes

The increased use of thermal decontamination procedures for fibrelight laryngoscope blades, to comply with international guidelines, will have considerable economical effects. We evaluated the effect of mechanical cleaning plus thermal disinfection at 90 degrees C, with or without subsequent steam sterilisation at 134 degrees C, on light intensity provided by fibrelight laryngoscopes. After mounting the blades in a special frame with a built-in light source, light intensity was measured using radiometer/photometer. In total, 14 blades provided by 11 companies were tested. The majority of fibrelight laryngoscope blades were fairly resistant to the damaging effects of machine washing plus disinfection at 90 degrees C (mean [range] reduction in light intensity 34.6%[2.1-78.3%]). However, when exposed to an additional sterilisation procedure at 134 degrees C, the majority of blades were unable to withstand the combined treatment for 300 cycles (mean [range] reduction in light intensity 86.5%[32.0-98.7%]). This study stresses the need for fibrelight laryngoscope blades which are more resistant to thermal decontamination procedures than those available at present.     

Eliminating protein from reusable laryngeal mask airways. A study comparing routinely cleaned masks with three alternative cleaning methods

Laryngeal mask airways (LMAs) have the potential to act as a vector for the transmission of prion diseases. This study was undertaken to define the problem of protein contamination and to investigate three alternative cleaning methods. Forty-eight LMAs were allocated to one of four groups, stained with erythrosin and given a total stain score and a grid stain score in order to determine the degree of protein contamination. Eighteen randomly selected LMAs that had been routinely cleaned and sterilised (group 1) were compared with 12 LMAs that had been washed and scrubbed with the benefit of prior staining (group 2), 13 that had been washed and scrubbed without any visual guide (group 3) and 13 that had been cleaned using a Biosonic ultrasonic cleaning system (group 4). The results show that none of the cleaning methods achieved optimal results, as all methods left proteinaceous material on some masks. The study showed that: (i) staining as a guide to cleaning does not lead to more effective removal of proteinaceous material; (ii) systematic cleaning and scrubbing does lead to more effective removal of proteinaceous material from surfaces other than the grid area; and (iii) ultrasonic cleaning was more effective than other methods of cleaning for the removal of proteinaceous material from those areas of the mask most inaccessible, such as the grid.     

Mechanisms contributing to the vaso-active effects of prilocaine in human skin

We investigated the roles of the endothelial nitric oxide and cyclo-oxygenase pathways in mediating the vasoactivity of prilocaine in the skin. We injected prilocaine 1% intradermally into forearm skin of 10 healthy, male subjects. Nitric oxide synthesis was inhibited at a second site by co-injecting prilocaine with l-NAME 1%. We then repeated the injections while blocking the cyclo-oxygenase pathway with aspirin (4 x 600 mg). We measured blood flow responses to the injections using laser Doppler imaging. We found that, after the traumatic effects of injection had subsided, l-NAME reduced the vascular response to prilocaine by a third (p = 0.012), indicating an influence specifically on the drug response. Aspirin had no effect on the response (p = 0.588). We conclude that the vasoactive effects of prilocaine in human skin are mediated partly through the release of endothelial nitric oxide and, although other mechanisms might also be involved, the cyclo-oxygenase pathway does not appear to play a role.     

等离子灭菌设备及其控制过程的设计

分析了等离子灭菌的原理,并据此给出了过氧化氢低温等离子灭菌的过程及设备的工作流程图;提出了系统设计的要求,并据此架构了系统组成框图;根据对密封门运动过程的分析,提出了可编程逻辑器件控制其运动的状态图;微控制器是整个系统的主控制器,通过微控制器控制系统工作的程序流程图也给出。     

医院大型影像设备机房建设及安装准备工作探讨

分析了当前医院大型影像设备房屋建设及安装准备工作中存在的问题;阐述了医院影像科在选址、布局、房屋建设、安全防护及环境控制等方面应遵循的原则及要求;对大型影像设备安装及房屋设计、改建,提出新的观点和建议。