Noninvasive single-beat determination of left ventricular end-systolic elastance in humans

OBJECTIVES: The goal of this study was to develop and validate a method to estimate left ventricular end-systolic elastance (E(es)) in humans from noninvasive single-beat parameters. BACKGROUND: Left ventricular end-systolic elastance is a major determinant of cardiac systolic function and ventricular-arterial interaction. However, its use in heart failure assessment and management is limited by lack of a simple means to measure it noninvasively. This study presents a new noninvasive method and validates it against invasively measured E(es). METHODS: Left ventricular end-systolic elastance was calculated by a modified single-beat method employing systolic (P(s)) and diastolic (P(d)) arm-cuff pressures, echo-Doppler stroke volume (SV), echo-derived ejection fraction (EF) and an estimated normalized ventricular elastance at arterial end-diastole (E(Nd)): E(es(sb)) = [P(d) - (E(Nd(est)) x P(s) x 0.9)[/(E(Nd(est)) x SV). The E(Nd) was estimated from a group-averaged value adjusted for individual contractile/loading effects; E(es(sb)) estimates were compared with invasively measured values in 43 patients with varying cardiovascular disorders, with additional data recorded after inotropic stimulation (n = 18, dobutamine 5 to 10 microg/kg per min). Investigators performing noninvasive analysis were blinded to the invasive results. RESULTS: Combined baseline and dobutamine-stimulated E(es) ranged 0.4 to 8.4 mm Hg/ml and was well predicted by E(es(sb)) over the full range: E(es) = 0.86 x E(es(sb)) + 0.40 (r = 0.91, SEE = 0.64, p < 0.00001, n = 72). Absolute change in E(es(sb)) before and after dobutamine also correlated well with invasive measures: E(es(sb)): DeltaE(es) = 0.86 x DeltaE(es(sb)) + 0.67 (r = 0.88, p < 0.00001). Repeated measures of E(es(sb)) over two months in a separate group of patients (n = 7) yielded a coefficient of variation of 20.3 +/- 6%. CONCLUSIONS: The E(es) can be reliably estimated from simple noninvasive measurements. This approach should broaden the clinical applicability of this useful parameter for assessing systolic function, therapeutic response and ventricular-arterial interaction.     

Continuous Measurement of Multiple Inert and Respiratory Gas Exchange in an Anaesthetic Breathing System by Continuous Indirect Calorimetry

A method was tested which permits continuous monitoring from a breathing system of the rate of uptake of multiple gas species, such as occurs in patients during inhalational anaesthesia. The method is an indirect calorimetry technique which uses fresh gas rotameters for control, regulation and measurement of the gas flows into the system, with continuous sampling of mixed exhaust gas, and frequent automated recalibration to maintain accuracy. Its accuracy was tested in 16 patients undergoing pre-cardiopulmonary bypass coronary artery surgery, breathing mixtures of oxygen/air and sevoflurane with/without nitrous oxide, by comparison with the reverse Fick method. Overall mean bias [95% confidence interval (CI)] of rate of uptake was 17.9 [7.3 to 28.5] ml min⁻¹ for oxygen, 0.04 [−0.42 to 0.50] ml min⁻¹ for sevoflurane, 10.9 [−16.1 to 37.8] for CO₂, and 8.8 [−14.8 to 32.4] ml min⁻¹ for nitrous oxide where present. The method proved to be accurate and precise, and allows continuous monitoring of exchange of multiple gases using standard gas analysis devices. Stuart-Andrews C, Peyton P, Humphries C, Robinson G, Lithgow B. Continuous measurement of multiple inert and respiratory gas exchange in an anaesthetic breathing system by continuous indirect calorimetry.     

Tinea Capitis: Fluconazole in Trichophyton tonsurans Infection

Abstract: Tinea capitis is the most common dermatophyte infection in children. Trichophyton tonsurans is the most common etiologic agent in the United States, and for more than four decades the standard therapy has been griseofulvin. The availability of newer, and often more effective, antifungal drugs creates the opportunity for choice and the ability to optimally tailor treatment for a particular patient. Fluconazole is an azole antifungal drug available in a pleasant, well-tolerated, liquid formulation ideal for the pediatric population. It has a good safety profile and is approved in the United States for use in children, although not for tinea capitis. We present five patients with tinea capitis successfully treated with fluconazole.     

Manipulation: investigation of a proposed mechanism

The purpose of this study was to investigate whether spinal manipulation alters the posteroanterior stiffness of the manipulated region. Thirty subjects with no history of thoracic pain or contraindication to manipulation participated. The manipulation studied was a posteroanterior thrust applied to the T_4–5 spinal level. The effect of the manipulation was compared to a control intervention of supine lying. The posteroanterior stiffness of all subjects was measured at the T₄ and T₅ levels initially, and remeasured after both the manipulation and control interventions. Change scores relating to the change in posteroanterior stiffness due to manipulation and due to the control intervention were computed. A t-test comparing the change scores between interventions revealed no significant difference. However, the posteroanterior stiffness at T₅ was found to be significantly greater than at T₄. It was concluded that in the case of asymptomatic subjects these results did not provide support for the hypothesis that posteroanterior stiffness is altered by manipulation.     

Onychomycosis and diabetes

Objective  This study aims to discuss factors specific to diabetics in the diagnosis and treatment of onychomycosis.
Discussion  Onychomycosis has the potential to cause severe complications in diabetics and should be treated promptly. The existence of comorbid conditions and potential for drug–drug interactions complicates the selection of an appropriate treatment regimen. The role of Candida in onychomycosis is controversial but may be of increased significance in the diabetic population due to an underlying vulnerability to this organism.
Conclusions  Terbinafine is an excellent choice in diabetics due to its low risk of drug–drug interaction and proven efficacy against the typical pathogens that cause onychomycosis. Itraconazole, while an effective treatment for onychomycosis, is not a first-choice therapy due to its black-box cardiac warning and numerous drug interactions. Larger studies are needed in diabetics to determine the frequency of candidal nail infections.