Biomedical subjects

P Volkert

Publications and source records attributed to P Volkert.

3 recordsLinked to original sources

PubMed1997

Comparison of free range and graded exercise testing.

Previous studies with athletes have demonstrated greater physiologic responses during free range (FR) compared with graded (GXT) exercise testing. Since the sensitivity of clinical exercise testing depends upon the magnitude of physiologic responses, we sought to determine whether FR might provoke greater responses than GXT in nonathletic individuals and patients. Healthy, physically active nonathletes and clinically stable CHD patients (N = 12) performed GXT on cycle ergometer (15 W + 15 W.min-1) and FR (minimal time for 75 kJ task) on a cycle ergometer. A starting power output was recommended for FR, but the patients were free to pedal at their own rates. During FR, VO2max (36.5 +/- 10.1 vs 34.1 +/- 9.4 mL.min-1.kg-1), HRmax (156 +/- 25 vs 144 +/- 27 beats.min-1), double product (31.4 +/- 4.9 vs 29.1 +/- 5.9) and VEmax (111 +/- 26 vs 94 +/- 17 L.min-1) were all significantly greater than during cycle GXT. The mean peak power output during GXT (180 +/- 45 W) was not significantly different than the mean power output during FR (204 +/- 45 W). During FR, successive "0.5 mile laps" (approximately 12.5 kJ) were accomplished at power outputs of 217 +/- 45, 217 +/- 52, 192 +/- 60, 194 +/- 65, 199 +/- 63, and 207 +/- 63 W. No patient experienced angina or ECG changes during either FR or GXT. The patients uniformly reported that FR felt like "hurrying" in the real world. Some patients had to make large reductions in their power output in mid ride to allow recovery from a too aggressive start, much as they would in the real world. We conclude that FR exercise provides a clinically useful method of exercise testing that is not only more like real world exercise patterns but also provokes greater physiologic responses than are achievable during conventional GXT.

Adult↗

PubMed1995

Fee-for-service versus capitation-based reimbursement: how the payment method affects utilization of echocardiographic services by referring physicians.

Historically, health insurance carriers (HIC) have reimbursed physicians on a fee-for-service basis for echocardiographic studies. With the emergence of managed care, the HIC now may have the option of paying on a capitation basis. To determine whether the method of reimbursement had any bearing on the types of patients referred for echocardiographic services, we conducted a two-phase (retrospective) study. In Phase One, we assessed two groups of ambulatory patients with regard to patient characteristics, medical reason for referral, and echocardiographic results. Group A (4,066 patients) had insurance plans that stipulated reimbursement for echocardiographic services as part of capitation for cardiology services. Group B (3,061 patients) had plans that reimbursed for echocardiographic services on a fee-for-service basis. In Phase Two, we assessed a total of 5,947 patients (3,833 from Group A and 2,114 from Group B) over a period of 40 months to determine the frequency of referral for a second echocardiogram within 2 years of a normal one and the repeat normalcy rate. The results showed that the capitation reimbursement group included younger, predominantly female patients who were referred more often for a more benign reason and who more frequently were diagnosed echocardiographically with less severe disease, higher rates of normalcy, and repeat normalcy. These findings suggest that in our geographic area the capitation method of reimbursement permitted more liberal utilization of echocardiographic services. In this era of cost awareness, the study suggests the need for better screening of patients referred for echocardiographic services.

Capitation Fee↗

PubMed1990

Fatal swine influenza pneumonia during late pregnancy.

Serious morbidity or death from swine influenza infection is unusual in the immunocompetent host. We present a fatal case of pneumonia caused by this virus in a previously healthy 32-year-old woman during her third trimester of pregnancy, and review all published case reports of swine influenza in United States civilians. Pregnancy may be a predisposing factor to fulminant infection with swine influenza virus.

Adult↗