Capacity planning for cardiac catheterization: a case study

BACKGROUND: Excessive waiting for procedures such as cardiac catheterization is an important issue for health care systems. Delays are generally attributed to a mismatch between demand and available capacity. Furthermore, due to the dynamic nature of short-term referral rates, procedure times, and patients' medical urgency, all of which are important contributors to the problem of excessive waiting time, it has been difficult to predict capacity needs accurately. The objective of our paper is to demonstrate how such calculations could be performed. METHODS: After constructing a patient flow model and populating it with appropriate data from 16 consecutive months of operations (n=6215 referrals) of a regional cardiac centre in Ontario, we used computer simulation to simulate the operations of catheterization laboratories in several "what-if" scenarios. We divided the patients into three urgency categories: U1--hospitalized patients, U2--urgent outpatients, U3--elective outpatients. We tested the accuracy of the model by comparing a 1-year sample of computer simulation with actual data which resulted in a highly significant correlation of 0.94. RESULTS: We observed from the referral cohort that waiting times were long, both overall and within each urgency category. We observed from the simulation models that: (1) a one-time infusion of capacity to clear the backlog failed to reduce the waiting times; (2) targeting extra capacity to highest urgency categories reduced waiting times overall and also benefited low urgency patients for whom specific increased capacity was not earmarked; (3) there were no significant effects on waiting times if in some cases patients or referring physicians were able to choose their cath physician; and (4) in situations where the arrival rates increased overall or within specific urgency categories, waiting times increased dramatically and failed to return to baseline for several months to years for the low urgency patients. Efficiency of the labs within the existing capacity could be improved by: (1) reducing changeover time between cases (2) externalizing and standardizing many of the pre- and post-procedural management of the patients, and (3) more carefully balancing the booking to reduce both slack and overtime. INTERPRETATION: Capacity determination is a complex and dynamic process. A combination of available clinical and administrative data, along with a computer simulation model, helps predict capacity needs and is the most appropriate strategy to minimize waiting of patients for procedures. This approach is generalizable and can lead to more effective management of waiting lists for a variety of procedures.     

超声心动图二尖瓣及肺静脉血流图和心导管法评定左心室舒张功能的研究

目的为了评定冠心病左心室舒张功能变化,也为临床探讨一种较为可靠的左室舒张功能检测指标,本研究对冠心病患者左室舒张功能进行检测.方法 132例住院患者,分为正常组、心绞痛组和心肌梗死组,采用经胸超声心动图二尖瓣、肺静脉血流图和心导管法进行左室舒张功能检测.结果研究显示与正常组比较,心绞痛组左室舒张功能轻度异常,为驰张型舒张障碍,表现为AVTI增大、EVTI/AVTI降低、E/A＜1、AETp延长、AETp-AET＜0、T增大.心肌梗死组左室舒张功能中度异常,表现为E/A＞1、IVRT DT正常、LVEDP增高、AETp-AET＞0.结论心绞痛及心肌梗死均存在左室舒张功能异常,心肌梗死组重于心绞痛组,心绞痛组为轻度异常,心肌梗死组为中度异常,二尖瓣、肺静脉血流图联合应用可以估测大多数左心室舒张功能异常.     

彩色多普勒超声对主动脉夹层的诊断及临床价值

目的探讨彩色多普勒超声在主动脉夹层（AD）的诊断及临床应用价值。方法对15例手术确诊主动脉夹层患者的彩色多普勒超声检查资料进行分析。结果彩色多普勒超声能清晰显示撕裂的内膜、累及的范围、分辨真假腔及破口的位置,并能对主动脉夹层进行细分型。结论彩色多普勒超声可成为临床诊断主动脉夹层的首选检查方法,对临床选择治疗方案及疗效评价具有重要的价值。     

超声心动图二尖瓣及肺静脉血流图和心导管法评定左心室舒张功能的研究

目的：为了评定冠心病左心室舒张功能变化，也为临床探讨一种较为可靠的左室舒张功能检测指标，本研究对冠心病患左室舒张功能进行检测。方法：132例住院患，分为正常组，心绞痛组和心肌梗死组，采用经胸超声心动图二尖瓣，肺静脉血流图和心导管法进行左室舒张功能检测。结果．；研究显示与正常组比较，心绞痛组左室舒张功能轻度异常，为驰张型舒张障碍，表现为AVTI增大，EVTI／AVTI降低，E／A＜1，AETP延长，AETP－AET＜0，T增大，心肌梗死组左室舒张功能中度异常，表现为E／A＞1，IVRT DT正常，LVEDP增高，AETP－AET＞0。结论：心绞痛及心肌梗死均存在左室舒张功能异常，心肌梗死组重于心绞痛组，心绞痛组为轻度异常，心肌梗死组为中度异常，二尖瓣，肺静脉血流图联合应用可以估测大多数左心室舒张功能异常。     

Doppler echocardiography in the examination of normally functioning artificial mitral and aortic valves

Patients with prosthetic valves were investigated by Doppler echocardiography in 902 cases between November 1987 and February 1990. The parameters of 209 of 344 mitral and 258 of 299 aortic prosthetic valves were evaluated. No significant correlation was found between the type of aortic or mitral prosthetic valves and the measured gradient. As concerns the size of the valve and the measured gradient, a close correlation for aortic valve replacement was detected. For a normally functioning mitral prosthetic valve, a maximum early diastolic velocity of less than 2 m/s (16 mm Hg gradient) and a pressure half-time of less than 130 ms (mitral valve area 1.8 cm2) were characteristic. In cases of aortic valve replacements, the maximum velocity was less than 3 m/s (36 mm Hg gradient), except for the small-diameter valves. More than 95% of the cases met these criteria. (Even if small-diameter valves were included, a maximum velocity of more than 3 m/s occurred only in 8.9%.) Doppler echocardiography is a suitable tool for detecting normal prosthetic valve function, while colour Doppler allows the optimal alignment of jet direction and Doppler beam.     

Successful delivery of a patient with two artificial valves (mitral and aortic)

The authors report the case of the successful delivery of a 35-year old woman who underwent a double Sorin tilting disc valve replacement because of severe mitral and aortic valve disease in NYHA III-IV. functional class six years ago. Beside reporting on outcome of the case and complications, they mention the possible other complications too, endangering the life prospects of the mother and child that can come about as a result of the diminished pump function of the myocardium, blood coagulation changed during pregnancy and due to the hemmorrhagic and teratogenic consequences of anticoagulant treatment.     

两种方法监测紫外线灯辐照强度比较及效果评价

目的为观察紫外线灯辐照强度的常规监测法与改进后监测法比较,评价临床实际应用中的效果。方法将常规监测法即直接在临床现场进行紫外线灯辐照强度监测作为对照组,将改进后监测方法作为试验组。结果常规监测法对监测人员的眼睛和皮肤均有不同程度损伤,紫外线灯管辐照强度的合格率新灯管为93.3%,使用中灯管为90.4%;使用改进后监测方法,对监测人员不会造成皮肤和眼睛等损伤,紫外线灯管辐照强度的合格率新灯管为100.0%,使用中灯管为98.3%。结论使用改进后方法进行紫外线灯辐照强度监测不会伤害监测人员,方法规范,准确性高。     

Validity of conjoint analysis to study clinical decision making in elderly patients with aortic stenosis

OBJECTIVE: Written case simulations are increasingly being used to investigate clinical decision making. Our study was designed to determine the validity of written case simulations within a conjoint analysis approach. STUDY DESIGN AND SETTING: We developed a series of 32 written case simulations that differed with respect to nine clinical characteristics. These case simulations represented elderly patients with aortic stenosis. The clinical characteristics varied according to a fractional factorial design. We analyzed retrospectively all consecutive patients of 70 years of age or older with an aortic stenosis in three university hospitals. RESULTS: 34 cardiologists from three Dutch hospitals gave their treatment advice to each of these case simulations on a six-point scale (ranging from 'certainly no' to 'certainly yes' to surgical treatment). We compared the influence that the clinical characteristics had on the responses to these case simulations with their influence on the actual treatment decision for 147 actual patients in the same three hospitals. We found a strong agreement. This agreement was only slightly affected by the cut-off value used to dichotomize the treatment advice into a recommendation in favor of or against surgical treatment. CONCLUSION: Written case simulations reflect well how clinicians are influenced by specific clinical characteristics of their patients.     

Adoption of an innovation to repair aortic aneurysms at a Canadian hospital: a qualitative case study and evaluation

Background

Priority setting in health care is a challenge because demand for services exceeds available resources. The increasing demand for less invasive surgical procedures by patients, health care institutions and industry, places added pressure on surgeons to acquire the appropriate skills to adopt innovative procedures. Such innovations are often initiated and introduced by surgeons in the hospital setting. Decision-making processes for the adoption of surgical innovations in hospitals have not been well studied and a standard process for their introduction does not exist. The purpose of this study is to describe and evaluate the decision-making process for the adoption of a new technology for repair of abdominal aortic aneurysms (endovascular aneurysm repair [EVAR]) in an academic health sciences centre to better understand how decisions are made for the introduction of surgical innovations at the hospital level.

Methods

A qualitative case study of the decision to adopt EVAR was conducted using a modified thematic analysis of documents and semi-structured interviews. Accountability for Reasonableness was used as a conceptual framework for fairness in priority setting processes in health care organizations.

Results

There were two key decisions regarding EVAR: the decision to adopt the new technology in the hospital and the decision to stop hospital funding. The decision to adopt EVAR was based on perceived improved patient outcomes, safety, and the surgeons' desire to innovate. This decision involved very few stakeholders. The decision to stop funding of EVAR involved all key players and was based on criteria apparent to all those involved, including cost, evidence and hospital priorities. Limited internal communications were made prior to adopting the technology. There was no formal means to appeal the decisions made.

Conclusion

The analysis yielded recommendations for improving future decisions about the adoption of surgical innovations. ese empirical findings will be used with other case studies to help develop guidelines to help decision-makers adopt surgical innovations in Canadian hospitals.