Brad Dalton

Sodium bicarbonate can be used as an ergogenic aid in high-intensity, competitive cycle ergometry of 1 h duration

Abstract The aim of this study was to determine whether a dose of 300-mg · kg−1 body mass of sodium bicarbonate would effect a high-intensity, 1- h maximal cycle ergometer effort. Ten male, well-trained [maximum oxygen consumption 67.3 (3.3) ml · kg−1 · min−1, mean (SD)] volunteer cyclists acted as subjects. Each undertook either a control (C), placebo (P), or experimental (E) ride in a random, double-blind fashion on a modified, air-braked cycle ergometer, attached to a personal computer to which the work and power data was downloaded at 10 Hz. Fingertip blood was sampled at 10-min intervals throughout the exercise. Blood was also sampled at 1, 3, 5, and 10 min post-exercise. Blood was analysed for lactate, partial pressure of Carbon dioxide and oxygen, pH and plasma bicarbonate (HCO−3) concentration. Randomly chosen pairs of subjects were asked to complete as much work as possible during the 60-min exercise periods in an openly competitive situation. The sodium bicarbonate had the desired effect of increasing blood HCO−3 prior to the start of the test. The subjects in E completed 950.9 (81.1) kJ of work, which was significantly more (F(2,27) = 5.28, P < 0.01) than during either the C [835.5 (100.2) kJ] or P [839.0 (88.6) kJ] trials. No differences were seen in peak power or in the power:mass ratio between these three groups. The results of this study suggest that sodium bicarbonate may be used to offset the fatigue process during high-intensity, aerobic cycling lasting 60 min.

Prevalence of pulmonary arterial hypertension in an Australian scleroderma population: screening allows for earlier diagnosis

Background:  We sought to determine the prevalence of pulmonary complications and especially pulmonary arterial hypertension (PAH) in an Australian scleroderma population.

The effects of creatine supplementation on high-intensity exercise performance in elite performers.

Abstract The aim of this research was to determine whether creatine supplementation at a dose of 20 g · day−1, given in 4 × 6-g doses (5 g creatine monohydrate and 1 g glucose) for 5 days, was effective in improving kayak ergometer performances of different durations. Sixteen male subjects with the following characteristics [mean (SEM)]: age 21 (1.2) years, height 170.2 (1.7) cm, weight 75.3 (2.3) kg, Σ8 skinfolds 59.3 (2.6) mm, and maximal oxygen consumption 67.1 ± (4.3) ml · kg · min−1, undertook three maximal kayak ergometer tests of 90, 150 and 300 s duration on a wind-braked kayak ergometer (CON). Two groups were then randomly formed, with one group taking the supplement (SUP) while the other took a placebo (PLAC). No pre-test differences existed between the SUP and the PLAC groups in any of the variables measured. After supplementation each group then repeated the same kayak ergometer tests as performed previously and after a 4-week “washout period” the groups took either the PLAC or SUP for another 5 days and then completed the final tests. The SUP group completed significantly more work than either the CON or PLAC groups in all of the tests (90 s, P < 0.01; 150 s, P < 0.001; 300 s, P < 0.05). Body mass remained stable throughout the test period in both the CON and PLAC groups, but both were significantly less than the SUP body mass of 77.3 (1.0) kg (P < 0.01). The results of this work indicate that creatine supplementation can significantly increase the amount of work accomplished during kayak ergometer performance at durations ranging from 90 to 300 s.

The bosentan patient registry: long-term survival in pulmonary arterial hypertension

Background/Aims: The Bosentan Patient Registry (BPR) was a prospective, multicentre, Australian registry funded by Actelion Pharmaceuticals. The primary aim of the registry was to collect survival data in patients with pulmonary arterial hypertension (PAH) treated with bosentan.

Survival after the initiation of combination therapy in patients with pulmonary arterial hypertension: an Australian collaborative report.

Background:  Several cellular pathways are implicated in the pathogenesis of pulmonary arterial hypertension (PAH) and attempts to arrest disease progression with a single drug would not be expected to succeed in the medium term. In clinical practice, combination therapy is often used in patients deteriorating on monotherapy, despite the absence of firm evidence from randomized controlled controls.

Efficacy, safety and tolerability of bosentan in Chinese patients with pulmonary arterial hypertension.

BACKGROUND Bosentan has an established role in the management of pulmonary arterial hypertension (PAH). This clinical trial assessed the benefits of bosentan in the Chinese population. METHODS We investigated the efficacy and safety of bosentan in 92 Chinese citizens (mean +/- standard deviation age, 29.0 +/- 3.8 years) with PAH for a minimum of 12 weeks. All received bosentan (62.5 mg twice daily) for 4 weeks; then, patients who weighed <40 kg received 62.5 mg bosentan twice daily and patients who weighed >40 kg received 125 mg twice daily. All patients were eligible to continue bosentan beyond 12 weeks. The primary end point was a change in exercise capacity from baseline to 12 and 24 weeks. Secondary end points included a change in World Health Organization (WHO) functional class and changes in cardiopulmonary hemodynamics. RESULTS At baseline, 66 patients (72%) were in WHO functional class III; presentation was 37 (40%) with idiopathic PAH (iPAH), 34 (37%) with PAH related to congenital heart disease (CHD), and 21 (23%) with PAH related to connective tissue disease (CTD). Exercise capacity increased to 67.8 m after 12 weeks and 92.6 m after 24 weeks (p < 0.001). After 24 weeks, WHO functional class decreased (-0.8 +/- 0.6; p < 0.001), mean pulmonary artery pressure and pulmonary vascular resistance decreased (p < 0.01), and cardiac output increased (p < 0.001). Twelve patients (13%) experienced at least 1 adverse event. CONCLUSIONS Bosentan improved exercise capacity, functional class, and cardiopulmonary hemodynamics in this patient cohort and was well tolerated.

Hemodynamics in pulmonary arterial hypertension (PAH): do they explain long-term clinical outcomes with PAH-specific therapy?

BackgroundPulmonary arterial hypertension (PAH) has witnessed dramatic treatment advances over the past decade. However, with the exception of epoprostenol, data from short-term randomized controlled trials (RCTs) have not shown a benefit of these drugs on survival. There remains a need to differentiate between available therapies and current endpoint responses which in turn, could be used to guide treatment selection and provide long-term prognostic information for patients.MethodsWe performed a systematic literature search of MEDLINE and EMBASE databases for RCTs of PAH-specific therapy published between January 1980 and May 2009. Articles were selected if they contained a placebo comparator and described hemodynamic changes from baseline. We applied the weighted mean change in hemodynamic variables to the equation developed by the National Institutes of Health (NIH) Registry to estimate long-term survival with each therapy.ResultsTen RCTs involving 1,635 patients met the inclusion criteria. Suitable hemodynamic data were identified for bosentan, sitaxentan, sildenafil, epoprostenol, beraprost and treprostinil. 77.6% of patients were female and the mean (SD) age was 46.5 ± 4.9 years. 55.5% of patients had idiopathic PAH (iPAH), 23.9% PAH related to connective tissue disease, and 18.2% PAH related to congenital heart disease. Based on the effects observed in short-term trials and, relative to placebo, all analyzed therapies improved survival. The estimated 1-year survival was 78.4%, 77.8%, 76.1%, 75.8%, 75.2%, and 74.1% for epoprostenol, bosentan, treprostinil, sitaxentan, sildenafil, and beraprost, respectively. These estimates are considerably lower than the 1-year observed survival reported in several open-label and registry studies with PAH-specific therapies: 88% - 97%.ConclusionWhen applied to the NIH Registry equation, hemodynamic changes from baseline appear to underestimate the survival benefits observed with long-term PAH therapy.

Screening and management of renal disease in human immunodeficiency virus-infected patients in Australia

Renal disease has become one of the most important comorbidities observed in the human immunodeficiency virus (HIV)‐infected patient cohort. Data are lacking on the current screening and management of renal disease in patients with HIV. We evaluated HIV‐infected Australian adults in primary care to determine current practices.

integrated care and optimal management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) may occur as an idiopathic process or as a component of a variety of diseases, including connective tissue diseases, congenital heart disease, and exposure to appetite suppressants or infectious agents such as HIV. Untreated, it is a potentially devastating disease; however, diagnosis can be difficult due to the non-specific nature of symptoms during the early stages, and the fact that patients often present to a range of different medical specialties. The past decade has seen remarkable improvements in our understanding of the pathology associated with the condition and the development of PAH-specific therapies with the ability to alter the natural history of the disease. This article reviews the evidence for screening and diagnosis of susceptible patient groups and discusses treatment selection and recommendations based on data available from randomized controlled trials. In addition, due to the complexity of the diagnostic evaluation required and the treatment options available, this review mandates for a multidisciplinary approach to the management of PAH. We discuss the roles and organizational structure of a specialized PAH center in Perth, Western Australia to highlight these issues.

Screening and management of cardiovascular disease in Australian adults with HIV infection

BACKGROUND Cardiovascular disease (CVD) is common in HIV infection. With no specific Australian guidelines for the screening and management of CVD in HIV-infected patients, best clinical practice is based on data from the general population. We evaluated adherence to these recommendations by primary care physicians who treat HIV-infected patients. METHODS Primary care physicians with a special interest in HIV infection were asked to complete details for at least 10 consecutive patient encounters using structured online forms. This included management practices pertaining to blood pressure (BP), blood glucose, electrocardiogram, lipid profile and CVD risk calculations. We assessed overall adherence to screening and follow-up recommendations as suggested by national and international guidelines. RESULTS Between May 2009 and March 2010, 43 physicians from 25 centres completed reporting for 530 HIV-infected patients, of whom 93% were male, 25% were aged 41-50 years and 83% were treated with antiretrovirals. Risk factors for CVD were common and included smoking (38%), hyperlipidaemia (16%) and hypertension (28%). In men aged >40 years and women aged >50 years without evidence of ischaemic heart disease, only 14% received a CVD risk assessment. Lipid and BP assessments were performed in 87% and 88% of patients, respectively. CONCLUSIONS This Australian audit provides unique information on the characteristics and management of HIV and CVD in clinical practice. We have found a high burden of risk for CVD in HIV-infected Australians, but current screening and management practices in these patients fall short of contemporary guidelines.