What Is the Best Dialysis Therapy for South Asia: HD or PD?

BACKGROUND: South Asian countries have a population of 1.7 billion and are classified as low-middle to poor income nations. Their health care systems cannot presently meet the growing need for renal replacement therapy (RRT), provided as haemodialysis or peritoneal dialysis (PD). Most patients cannot afford the treatment and quickly default. Furthermore, most of the population is located in rural areas, where there are few treatment centres; therefore, there is a huge gap between those treated and those in need. SUMMARY: PD can bridge this gap and can serve as a first line of therapy if it becomes more affordable. Government reimbursement schemes, the Once-in-a-Lifetime Payment Scheme, and PD insurance all provide strong impetus to dialysis programmes. Local manufacturing of PD fluid has also reduced the cost of therapy to some extent. PD may be preferable for patients with cardiovascular morbidity and it also obviates the risk of transmission of blood-borne diseases such as HIV, hepatitis B, and hepatitis C. In our own centre, automated PD is being used as initial RRT for acute kidney injury with good results. In prospective transplant recipients, PD has been found to decrease the risk of posttransplant graft dysfunction. Key Messages: Remote PD and home visits by PD clinical coordinators have brought faraway patients and their nephrologists closer with the use of technology. For these reasons, the current pressing need is to bring PD to the forefront of RRT in resource-poor countries in South Asia to enable universal treatment of patients with renal disease.

Model-based stability assessment of ventilatory control in overweight adolescents with obstructive sleep apnea during NREM sleep.

Obstructive sleep apnea (OSA) involves the interplay of several different factors such as an unfavorable upper airway anatomy, deficiencies in pharyngeal muscle responsiveness, a low arousal threshold, and ventilatory control instability. Although the stability of ventilatory control has been extensively studied in adults, little is known about its characteristics in the pediatric population. In this study, we developed a novel experimental setup that allowed us to perturb the respiratory system during natural non-rapid eye movement (NREM) sleep conditions by manipulating the inspiratory pressure, provided by a bilevel pressure ventilator, to induce sighs after upper airway stabilization. Furthermore, we present a modeling framework that utilizes the noninvasively measured ventilatory responses to the induced sighs and spontaneous breathing data to obtain representations of the processes involved in the chemical regulation of respiration and extract their stability characteristics. After validation with simulated data, the modeling technique was applied to data collected experimentally from 11 OSA and 15 non-OSA overweight adolescents. Statistical analysis of the model-derived stability parameters revealed a significantly higher plant gain and lower controller gain in the OSA group (P = 0.046 and P = 0.007, respectively); however, no differences were found in loop gain (LG) and circulatory time delay between the groups. OSA severity and LG, within the 0.03-0.04-Hz frequency band, were significantly negatively associated (r = -0.434, P = 0.026). Contrary to what has been found in adults, our results suggest that in overweight adolescents, OSA is unlikely to be initiated through ventilatory instability resulting from elevated chemical loop gain.

Noninvasive identification and assessment of functional brown adipose tissue in rodents using hyperpolarized ¹³C imaging.

OBJECTIVE: The recent identification of functional depots of brown adipose tissue (BAT) in adult humans has potential implications for the treatment of obesity. In order to evaluate new therapies aimed at inducing the production of more BAT or activating BAT in humans, it will be important to develop noninvasive methods to assess the functional state of the tissue in vivo. In this study, we investigate the feasibility of using hyperpolarized (13)C imaging to noninvasively identify functional, activated BAT in an in vivo rodent model, in less than 1 min, following an infusion of pre-polarized [1-(13)C] pyruvate. DESIGN: Hyperpolarized (13)C imaging was used to monitor BAT metabolic conversion of pre-polarized [1-(13)C] pyruvate in rats during baseline and norepinephrine (NE)-stimulated conditions. RESULTS: Activated BAT, stimulated by NE injection, can be detected in rats by increased conversion of pre-polarized [1-(13)C] pyruvate into its downstream products (13)C bicarbonate and [1-(13)C] lactate. The colocalization of the (13)C signal to interscapular BAT was validated using hematoxylin-eosin histological staining. CONCLUSION: The radiation-free nature and recent translation into the clinic of the hyperpolarized (13)C-imaging test may potentially facilitate trials of therapeutics targeting BAT activation in humans.

Assessment of abdominal adipose tissue and organ fat content by magnetic resonance imaging.

As the prevalence of obesity continues to rise, rapid and accurate tools for assessing abdominal body and organ fat quantity and distribution are critically needed to assist researchers investigating therapeutic and preventive measures against obesity and its comorbidities. Magnetic resonance imaging (MRI) is the most promising modality to address such need. It is non-invasive, utilizes no ionizing radiation, provides unmatched 3-D visualization, is repeatable, and is applicable to subject cohorts of all ages. This article is aimed to provide the reader with an overview of current and state-of-the-art techniques in MRI and associated image analysis methods for fat quantification. The principles underlying traditional approaches such as T(1) -weighted imaging and magnetic resonance spectroscopy as well as more modern chemical-shift imaging techniques are discussed and compared. The benefits of contiguous 3-D acquisitions over 2-D multislice approaches are highlighted. Typical post-processing procedures for extracting adipose tissue depot volumes and percent organ fat content from abdominal MRI data sets are explained. Furthermore, the advantages and disadvantages of each MRI approach with respect to imaging parameters, spatial resolution, subject motion, scan time and appropriate fat quantitative endpoints are also provided. Practical considerations in implementing these methods are also presented.

Peritoneal dialysis in developing countries.

Peritoneal dialysis (PD) is acknowledged worldwide as a well-accepted form of renal replacement therapy (RRT) for end-stage renal disease (ESRD). Ideally, PD should be the preferred modality of RRT for ESRD in developing countries due to its many inherent advantages. Some of these are cost savings (especially if PD fluids are manufactured locally or in a neighboring country), superior rehabilitation and quality of life (QOL), home-based therapy even in rural settings, avoidance of hospital based treatment and the need for expensive machinery, and freedom from serious infections (hepatitis B and C). However, this is not the ground reality, due to certain preconceived notions of the health care givers and governmental agencies in these countries. With an inexplicable stagnation or decline of PD numbers in the developed world, the future of PD will depend on its popularization in Latin America and in Asia especially countries such as China and India, with a combined population of 2.5 billion and the two fastest growing economies worldwide. A holistic approach to tackle the issues in the developing countries, which may vary from region to region, is critical in popularizing PD and establishing PD as the first-choice RRT for ESRD. At our center, we have been pursuing a 'PD first' policy and promoting PD as the therapy of choice for various situations in the management of renal failure. We use certain novel strategies, which we hope can help PD centers in other developing countries working under similar constraints. The success of a PD program depends on a multitude of factors that are interlinked and inseparable. Each program needs to identify its strengths, special circumstances, and deficiencies, and then to strategize accordingly. Ultimately, teamwork is the 'mantra' for a successful outcome, the patient being central to all endeavors. A belief and a passion for PD are the fountainhead and cornerstone on which to build a quality PD program.

Rapid ventricular assessment using real-time interactive multislice MRI.

A multislice real-time imaging technique is described which can provide continuous visualization of the entire left ventricle under resting and stress conditions. Three dynamically adjustable slices containing apical, mid, and base short axis views are imaged 16 times/sec (48 images/sec), with each image providing 3.12 mm resolution over a 20 cm field of view. Initial studies indicate that this technique is useful for the assessment of LV function by providing simultaneous real-time visualization of all 16 wall segments. This technique may also be used for stress LV function and, when used in conjunction with contrast agents, myocardial perfusion imaging. Magn Reson Med 45:371-375, 2001.