High-volume aspiration as a supplemental scavenging method for reducing ambient nitrous oxide levels in the operatory: a laboratory study

Occupational exposure to low levels of nitrous oxide (N2O) have been associated with adverse health effects. The National Institute for Occupational Safety and Health has established a threshold guideline of 25 ppm N2O. The purpose of this laboratory study was to determine the effectiveness of a high-volume dental aspirator as a supplemental device to reduce ambient N2O levels in the operatory. The investigation evaluated four experimental groups that were assigned based on whether or not the aspirator was used and on the rate at which operatory ventilation was established (5 or 10 room air exchanges per hour). Ambient N2O levels were monitored at 30 cm from the nasal hood using an infrared spectrophotometer. The room air exchange rate was measured with a flow hood and then manipulated to the desired ventilation rate. N2O levels were detected with a spectrophotometer and data were recorded with a microprocessor that continuously collected data. The results demonstrated that both utilization of supplemental oral aspiration and increased operatory ventilation significantly reduced ambient N2O levels. It was concluded that a high-volume aspirator, when used in conjunction with the normal scavenging system, can significantly reduce ambient N2O levels to within the guidelines established by the National Institute for Occupational Safety and Health.     

New technique for lesser saphenous vein harvesting

A new technique using the Thompson self-retaining retractor system (Thompson Surgical Instruments, Inc, Traverse City, MI) to harvest lesser saphenous veins is presented. This modification, used in 10 patients undergoing redo myocardial revascularization, provided a rapid, comfortable, and convenient method for harvesting lesser saphenous veins.     

Changing clinical practice. Prospective study of the impact of continuing medical education and quality assurance programs on use of prophylaxis for venous thromboembolism

OBJECTIVE: To determine the effect of continuing medical education (CME) with and without a quality assurance component (CME+QA) on physician practices in the prevention of venous thromboembolism. METHODS: A communitywide study was performed in 15 short-stay hospitals in central Massachusetts. The study population included 3158 patients in acute-care hospitals with multiple risk factors for venous thromboembolism. Study hospitals were randomly assigned to one of two educational strategies or to a control group that received no intervention. RESULTS: The proportion of patients at high risk for venous thromboembolism who received effective methods of prophylaxis increased significantly from 29% in 1986 to 52% in 1989 (P < .001). This increase was seen in all study groups: control hospitals, 40% to 51% (P < .001); CME hospitals, 21% to 49% (P < .0001); and CME+QA hospitals, 27% to 55% (P < .0001). The increase in prophylaxis use from 1986 to 1989 was significantly greater among patients cared for in hospitals whose physicians participated in a formal CME program (an increase of 28%) than in control hospitals (an increase of 11%) (P < .001). There was no significant difference in the use of prophylaxis in hospitals whose physicians received CME+QA interventions compared with hospitals whose physicians received CME interventions alone (identical increases of 28%). CONCLUSION: A formal CME program significantly increased the frequency with which physicians prescribed prophylaxis for venous thromboembolism. We believe the key factor in our CME interventions that motivated clinicians to change their practices was the provision of hospital-specific data demonstrating a compelling need for improvement. Despite the substantial investment by hospitals in QA, traditional QA intervention appeared to provide no additional benefit. Even after extensive CME/QA interventions, prophylaxis for venous thromboembolism remained underutilized, suggesting the need to develop new approaches to changing clinical practice.     

The development of an interdepartmental audit as part of a physics quality assurance programme for external beam therapy

A cost-effective audit system has been developed that will both detect systematic error in data and procedures and evaluate the quality assurance programme provided by a physics department for radiotherapy. The audit has been developed for external beam radiotherapy and assesses one modality and one treatment machine per year. The audit is carried out on an interdepartmental basis and can be undertaken by two physicists from each department in one working day. The method of assessing the quality assurance programme and the schedule of measurements are described. The process is illustrated using the results of trial audits between the medical physics departments at Coventry and Leicester.