Simulation of cerebral hemodynamics for preoperative risk assessment.

BACKGROUND: An important part of the medical treatment of many cerebrovascular diseases is the occlusion of brain supplying arteries. Until now, the risk of this intervention can only be estimated by invasive diagnostics including the risk of cerebrovascular accidents. METHODS AND RESULTS: As a supporting tool, a computer model of the circle of Willis was designed. The model is based upon linear differential equations describing electrotechnical circuits extended non-linearly. By these means, time continuous simulations of different states and the online observation of all calculated state variables such as blood pressure and blood flow in every modeled vessel became feasible. For individual simulations, model parameters were determined by MR-angiography and boundary values by simultaneous Duplex-measurements in both carotid and vertebral arteries. State variables generated by the model behaved physiologically and the reaction of individual cerebrovascular systems in critical situations could be investigated by special scenarios. Inaccuracies concerning the determination of model parameters and boundary values of the used differential equations are likely to be resolved in the near future through a more careful and technically improved determination of these values. CONCLUSIONS: Computer models of subjects were created taking in account the individual anatomical and non-linear physical properties of real vascular systems supplying the brain. Thereby information could be obtained concerning the hemodynamic effects of an iatrogenic vascular occlusion.

Development of a method to analyze orthopaedic practice expenses.

The purpose of the current investigation was to present a standard method by which an orthopaedic practice can analyze its practice expenses. To accomplish this, a five-step process was developed to analyze practice expenses using a modified version of activity-based costing. In this method, general ledger expenses were assigned to 17 activities that encompass all the tasks and processes typically performed in an orthopaedic practice. These 17 activities were identified in a practice expense study conducted for the American Academy of Orthopaedic Surgeons. To calculate the cost of each activity, financial data were used from a group of 19 orthopaedic surgeons in Houston, Texas. The activities that consumed the largest portion of the employee work force (person hours) were service patients in office (25.0% of all person hours), maintain medical records (13.6% of all person hours), and resolve collection disputes and rebill charges (12.3% of all person hours). The activities that comprised the largest portion of the total expenses were maintain facility (21.4%), service patients in office (16.0%), and sustain business by managing and coordinating practice (13.8%). The five-step process of analyzing practice expenses was relatively easy to perform and it may be used reliably by most orthopaedic practices.

Manage indirect practice expense the way you practice medicine: with information.

PURPOSE: Surgeons are increasingly faced with the pressures of maintaining the highest quality of patient care, while at the same time maintaining financial viability. The purpose of this project was to provide a framework for analyzing practice costs for colorectal surgeons using an activity-based cost accounting model. METHODS: A survey of 11 practices that were diverse in terms of geography, managed care penetration, academic vs. private practice style, and case distribution was performed. In activity-based costing the assignment of typical costs such as staff salaries are assigned to the appropriate business process. The business processes employed in this study were service patients in the office, perform in-office procedures, schedule cases in facilities, service patients in the hospital, insurance authorization, maintain medical records, billing, collections, resolve billing disputes, interaction with third parties, maintain professional education, sustain and manage the practice, maintain the facility, teaching and research, and performing drug studies. The final step is to assign the cost associated with all appropriate business processes to the appropriate cost object. The cost objects in this study were defined as a charge office visit, no-charge office visit, charge hospital visit, in-office procedures, in-facility procedures, and performing drug studies. The data were then analyzed to allow a comparison of four similar practices within the study group. RESULTS: The data demonstrated that the cost of seeing a charge office visit ranged from $55 to $105. Similarly, the cost of seeing a no-charge office visit during the global period ranged from $43 to $100. The study analyzed possible explanations for the wide variability in these costs. CONCLUSIONS: It is essential that physicians clearly understand the sources of expenses generated by the operation of their practices. A clear comprehension of costs will lead colorectal surgeons to make appropriate decisions regarding such important issues as office staffing ratios, office square footage, and instrumentation acquisitions.

Using activity-based costing to track resource use in group practices.

Research shows that understanding how resources are consumed can help group practices control costs. An American Academy of Orthopaedic Surgeons study used an activity-based costing (ABC) system to measure how resources are consumed in providing medical services. Teams of accounting professors observed 18 diverse orthopedic surgery practices. The researchers identified 17 resource-consuming business processes performed by nonphysician office staff. They measured resource consumption by assigning costs to each process according to how much time is spent on related work activities. When group practices understand how their resources are being consumed, they can reduce costs and optimize revenues by making adjustments in how administrative and clinical staff work.

Suppression of normal speech disfluencies through response cost.

The speech disfluencies of five normal-speaking college students were modified in a series of 10 to 17 sessions by means of response cost. During Point-loss, each disfluency (repetition or interjection of a sound, syllable, word, etc.) resulted in the loss of a penny, as indicated on a screen in front of the subject. Disfluencies were suppressed and kept at very low levels for four of the subjects during the punishment procedures, and there was general resistance to extinction. Even though points were subtracted only during speech, there was a tendency for disfluencies to decrease, though not as markedly, during reading probes as well.