Herbert Sherman

Protocols for physician assistants. Management of diabetes and hypertension.

Abstract Physician assistants used problem-oriented protocols in management of patients with diabetes and hypertension. The protocols directed the physician assistant in determining what data to co...

Pitfalls in the serial assessment of cardiac functional status: How a reduction in “ordinary” activity may reduce the apparent degree of cardiac compromise and give a misleading impression of improvement

Because the New York Heart Association (NYHA) classification system categorizes patients based on subjective impression of the degree of functional compromise, a reduction in exercise might make a patient seem improved because the new lower level of ordinary activity produced fewer symptoms. To test this hypothesis, we studied three different sets of patients and compared their NYHA classes to their functional classes as determined by a new Specific Activity Scale (SAS) that is based on the metabolic equivalents of oxygen consumption required for activities the patient actually performs. Among ambulatory patients referred for exercise tests, the NYHA class was higher (i.e. indicated the patient was more limited) in 28% of patients and the SAS class was higher in 14% (p less than 0.001). Among patients interviewed at or near the time of catheterization for chest pain, the NYHA was higher in 20% and the SAS class was higher in 20% (p = NS). In both medically and surgically treated patients interviewed 1--3 yr after cardiac catheterization, the NYHA class was higher in only 4%, whereas the SAS class was higher in 28% (p less than 0.001). The SAS class was significantly more likely to be higher in patients who were not working full time and in patients who described their present activity level as sedentary or light. When the NYHA and SAS systems disagreed as to whether a patient was improved, SAS was significantly more likely to correlate with the patients self-assessment. These findings suggest that some patients restrict their activity as their cardiac disease progresses; the resultant change in the definition of ordinary activity may reduce the apparent degree of cardiac compromise and thus give a false impression of improvement by NYHA criteria.

New Technique for Determining Instantaneous Myocardial Force-Velocity Relations in the Intact Heart

A new technique is described for the instantaneous determination of myocardial force-velocity relationships. The method employs electronic differentiation of the logarithm of intraventricular pressure, which yields a continuous on-line record of (dP/dt)P−1 (the ratio of the rate of rise of ventricular pressure [dP/dt] to the simultaneous ventricular pressure [P]). A further technique is described for the automatic projection of force-velocity vector loops, displaying (dP/dt)P−1 on the ordinate against ventricular pressure on the abscissa in a beat-to-beat fashion. An excellent correlation (r=0.982) was demonstrated between (dP/dt)P−1 determined by conventional methods and that derived electronically by use of the logarithmic amplifier circuit. Experimental studies are described which document the responsiveness of (dP/dt)P−1 determined by the present method to interventions known to affect myocardial contractility. An increase in (dP/dt)P−1 was observed following infusions of CaCl2, norepinephrine, and glucagon, and a decrease following pentobarbital. Insofar as (dP/dt)P−1 is a valid index of myocardial contractility, the present method permits on-line, beat-to-beat evaluation of changes in ventricular function under a variety of circumstances.

Clinical utility and management impact of M-mode echocardiography☆

To determine the clinical utility and management impact of M-mode echocardiography, 182 echocardiograms were analyzed at a university teaching hospital. The physicians who ordered the echocardiograms said that 12 percent provided crucial information that was not available from other tests and that 26 percent resulted in a change in patient management. According to two independent board-certified cardiologist-reviewers, 86 percent of echocardiograms were appropriately ordered, but only 15 echocardiograms (8 percent) were actually needed for a change to a new and appropriate management. According to the reviewers, the 77 Group I M-mode echocardiograms (those ordered to evaluate left ventricular function, left atrial size, potential cardiac sources of emboli, or the possibility of bacterial endocarditis, or those ordered in patients who, according to the ordering physician, had undergone or would undergo catheterization regardless of the results of echocardiography) were less likely than the 105 Group II M-mode echocardiograms (those ordered to evaluate possible mitral valve prolapse, hypertrophic cardiomyopathy, valvular function, or the pericardium) to be ordered appropriately, to provide helpful information, or to provide crucial results. Group I echocardiograms had reviewer-assessed appropriate management impact in only one case (1 percent) compared with a 13 percent rate of management impact for Group II M-mode echocardiograms (p less than 0.01). Although echocardiography can be accurate and valuable with yields similar to those of other noninvasive procedures, 77 (42 percent) of 182 M-mode echocardiograms in this hospital could be predicted at the time of ordering to be in a low-yield group.

Quality, Efficiency, and Cost of a Physician-Assistant-Protocol System for Managment of Diabetes and Hypertension

Briefly trained physicians assistants using protocols (clinical algorithms) for diabetes, hypertension, and related chronic arteriosclerotic and hypertensive heart disease abstrated information from the medical record and obtained history and physical examination data on every patient-visit to a city hospital chronic disease clinic over a 18-month period. The care rendered by the protocol system was compared with care rendered by a “traditional” system in the same clinic in which physicians delegated few clinical tasks. Increased thoroughness in collecting clinical data in the protocol system led to an increase in the recognition of new pathology. Outcome criteria reflected equivalent quality of care in both groups. Efficiency time-motion studies demonstrated a 20 per cent saving in physician time with the protocol system. Coct estimates, based on the time spent with patients by various providers and on the laboratory-test-ordering patterns, demonstrated equivalent costs of the two systems, given optimal staffing patterns. Laboratory tests were a major element of the cost of patient care,and the clinical yield per unit cost of different tests varied widely.

A pocket diagnostic calculator program for computing Bayesian probabilities for nine diseases with sixteen symptoms: Part A

Abstract We have demonstrated the use of a tape-controlled hand calculator for the bedside calculation of Bayesian probabilities for the differential diagnosis of up to 9 diseases and 16 symptoms. We have indicated the maneuvers required to store the requisite data as well as the effects of these maneuvers on the calculated results.

Measurement of Mitral Regurgitation by IndicatorDilution Tecirniques

Methods for quantifying mitral regurgitation that require the measurement only of the area enclosed by the indicator-dilution curves offer the advantage of being computationally simpler than the others. Furthermore, distortions in the shape of the curve will not necessarily induce significant error in the area enclosed by the curve. Since such methods require sampling from the atrium as well as from the ventricle, or proximal aorta, they will be successful only if meaningful samples of indicator concentration can be obtained from these chambers. The question remains to be answered: Is the mixing in the cardiac chambers sufficient to allow meaningful sampling in both atrium and ventricle? A review of the literature on this subject has been inconclusive.12–17 We are not aware of any experiments in which all of the conditions affecting cardiac chamber mixing have been controlled without seriously disturbing normal cardiac physiology. Such an experiment should control the nature of injection (i.e., one or many successive pulses), the number and placement of the orifices at the tip of the injection catheter, and the timing of the injection with the cardiac cycle. Experiments indicate that the optimum mixing conditions exist at the beginning of ventricular filling and that injection should be timed to coincide with this point in the cycle. It is of interest to note that, in the dye curve experiments by Sinclair et al.18 in which animals were used, the time at which injections were made was found to be unimportant. This important difference between the mixing characteristics of the mechanical model and an animal heart illustrates the difficulties encountered in the application of model results and observations to the human heart. It seems reasonable to conjecture, however, that the well-established mixing properties of flows through valves and orifices in rigid systems will be enhanced in the deformable wall situation encountered in the heart. Further experiments using the indicator-dilution technique on both normal and abnormal hearts are evidently required to determine the nature and extent of the dependence of measurement reliability on the sampling site location.

Surveillance Effects on Community Physician Test Ordering

The announcement that orders for long-term electrocardiograms were the subject of study in a community hospital was followed by a decrease in ordering rate of 30% from the corresponding quarter in the previous year. In succeeding quarters the decrement from corresponding quarters in the prior year was 21%, 27%, and 6%. Thereafter the ordering rate began to increase at a rate of 75% per year. In another community hospital in a contiguous town in which no surveillance was undertaken, the ordering rate for long-term electrocardiogram grew persistently at the rate of 42% per year over the same 3-year interval. The cardiologists at the community hospital under study behaved no differently as a group than other physicians in the community. The data strongly suggest that announced surveillance had the effect of diminishing long-term electrocardiogram tests ordered by community physicians by at least 20% for a period that lasts up to 9 months.

The Selective Impact of a Cardiology Data Bank on Physicians' Therapeutic Recommendations

We asked the physicians and medical students caring for 60 patients with symptomatic coronary artery disease, immediately after reviewing cardiac catheterization data, to choose medical or surgical therapy and to estimate prognosis one and three years after either therapy. The next day, each participant was given prognostic estimates generated from a large coronary artery disease data bank and again asked to estimate prognosis and choose therapy. Participants unanimously chose medicine for 20 patients (Group I) and surgery for 21 patients (Group III). For 19 patients (Group II), participants were divided on their choice of therapy. After seeing data bank estimates, participants rarely changed recommendations for Group I or Group III, but changed ten percent (9/90, p less than 0.01) of their Group II recommendations. Changes of recommendations by far (9/12, p = 0.02) favored medicine, causing the majority recommendation to change to medicine for two Group II patients. Therapeutic recommendations were guided mostly by pathoanatomy and the chance of improving medical regimens. Computer-generated prognostic data selectively influenced choices among the Group II cases where recommendations had been divided, resulting in changes toward less costly therapy.

Dissecting the hospital stay: a method for studying patient staging in hospitals.

A methodology is proposed and tested for the staging of patients thorugh a hospital stay. Measurements in a university-affiliated hospital and a community hospital in the Boston area showed similar staging patterns with about half of the sample having abnormal signs and symptoms while under treatment. The second-largest sample group in both hospitals, consisting of 11% of the sample, occupied beds although ready for discharge. The methodology indicated those patient-time units in the hospital which might be amenable to further reduction and gave upper bounds on that compression. Contrary to prior expectations, 90% of the patients sampled followed a well-defined sequence from admission to discharge with only 10% having complications of the admitting diagnosis, new diagnosis or iatrogenic illness.