SYMPTOM MANAGEMENT IN PATIENTS WITH ESTABLISHED RENAL FAILURE MANAGED WITHOUT DIALYSIS

Increasing numbers of patients with chronic kidney disease Stage 5 (GFR <15ml/minute) are being managed without dialysis, either through their own preference or because dialysis is unlikely to benefit them. This growing group of patients has extensive health care needs. Their overall symptom burden is high, and symptom prevalence matches or exceeds that in other end of life populations, both with cancer and other non-cancer diagnoses. These symptoms may often go unrecognised and under-treated. Regular symptom assessment is necessary, together with pro-active management of identified symptoms. Pain can be managed using the principles of the World Health Organisation analgesic ladder. Not all opioid medications are recommended for these patients. Paracetamol, tramadol, and fentanyl are the most appropriate medications for steps 1, 2 and 3 respectively. There is limited evidence on the use of buprenorphine, oxycodone and hydromorphone. Methadone is safe but should only be prescribed by a clinician experienced in its use. Morphine and diamorphine are not recommended because of metabolite accumulation. Pruritus is also challenging to manage. The evidence for pharmacological interventions to alleviate pruritus is summarized, and a pragmatic approach to management suggested. Emollients, capsaisin cream, antihistamines, thalidomide and ondansetron may be helpful, according to the extent and pattern of pruritus. Symptoms may frequently be due to co-morbid conditions, not renal disease itself, and managing them is difficult because of the constraints on the use of medication which kidney failure imposes. Collaboration between renal and palliative specialists can help identify ways to achieve best care for these patients.

End-of-life care in end-stage renal disease: renal and palliative care

The numbers of patients with end-stage renal disease are growing, with a disproportionate increase among those who are elderly, dependent and with multiple co-morbidities. More of these patients are choosing to be managed conservatively, without dialysis. Palliative provision for these patients within UK renal services is limited, but the recent National Service Framework for Renal Services (Department of Health, 2005) has promoted service development. However, few models of service provision have been described. This article describes a retrospective review of a new service for conservatively-managed patients with end-stage renal disease. The range and complexity of the health needs of this population is demonstrated, and an example of service development described. A model of the stages of the conservative pathway and appropriate interventions was developed. The absence of research evidence prevented development of formal audit standards, and highlighted the urgent need for evaluation of models of care.

A cluster of melioidosis cases from an endemic region is clonal and is linked to the water supply using molecular typing of Burkholderia pseudomallei isolates

Nine cases of melioidosis with four deaths occurred over a 28-month period in members of a small remote Aboriginal community in the top end of the Northern Territory of Australia. Typing by pulsed-field gel electrophoresis showed isolates of Burkholderia pseudomallei from six of the cases to be clonal and also identical to an isolate from the community water supply, but not to soil isolates. The clonality of the isolates found in this cluster contrasts with the marked genetic diversity of human and environmental isolates found in this region which is hyperendemic for B. pseudomallei. It is possible that the clonal bacteria persisted and were propagated in biofilm in the water supply system. While the exact mode of transmission to humans and the reasons for cessation of the outbreak remain uncertain, contamination of the unchlorinated community water supply is a likely explanation.

Alterations in outward K(+) currents on removal of external Ca(2+) in human atrial myocytes

External divalent cations are known to play an important role in the function of voltage-gated ion channels. The purpose of this study was to examine the sensitivity of the voltage-gated K(+) currents of human atrial myocytes to external Ca(2+) ions. Myocytes were isolated by collagenase digestion of atrial appendages taken from patients undergoing coronary artery-bypass surgery. Currents were recorded from single isolated myocytes at 37 degrees C using the whole-cell patch-clamp technique. With 0.5 mM external Ca(2+), voltage pulses positive to -20 mV (holding potential = -60 mV) activated outward currents which very rapidly reached a peak (I(peak)) and subsequently inactivated (tau = 7.5 +/- 0.7 msec at +60 mV) to a sustained level, demonstrating the contribution of both rapidly inactivating transient (I(to1)) and non-inactivating sustained (I(so)) outward currents. The I(to1) component of I(peak), but not I(so), showed voltage-dependent inactivation using 100 msec prepulses (V(1/2) = -35.2 +/- 0.5 mV). The K(+) channel blocker, 4-aminopyridine (4-AP, 2 mM), inhibited I(to1) by approximately 76% and reduced I(so) by approximately 33%. Removal of external Ca(2+) had several effects: (i) I(peak) was reduced in a manner consistent with an approximately 13 mV shift to negative voltages in the voltage-dependent inactivation of I(to1). (ii) I(so) was increased over the entire voltage range and this was associated with an increase in a non-inactivating 4-AP-sensitive current. (iii) In 79% cells (11/14), a slowly inactivating component was revealed such that the time-dependent inactivation was described by a double exponential time course (tau(1) = 7.0 +/- 0.7, tau(2) = 90 +/- 21 msec at +60 mV) with no effect on the fast time constant. Removal of external Ca(2+) was associated with an additional component to the voltage-dependent inactivation of I(peak) and I(so) (V(1/2) = -20.5 +/- 1.5 mV). The slowly inactivating component was seen only in the absence of external Ca(2+) ions and was insensitive to 4-AP (2 mM). Experiments with Cs(+)-rich pipette solutions suggested that the Ca(2+)-sensitive currents were carried predominantly by K(+) ions. External Ca(2+) ions are important to voltage-gated K(+) channel function in human atrial myocytes and removal of external Ca(2+) ions affects I(to1) and 4-AP-sensitive I(so) in distinct ways.

L-type calcium current of isolated rat cardiac myocytes in experimental uraemia

BACKGROUND

End-stage renal failure is associated with a low-output cardiomyopathy, left ventricular hypertrophy and increased QTc dispersion. Cardiac dysfunction is prevalent in patients at the beginning of dialysis and is an important predictor of mortality. Ca(2+) influx through voltage-gated L-type Ca(2+) channels plays a key role in the excitation-contraction coupling of cardiac myocytes. The purpose of this study was to examine the effect of subtotal nephrectomy (SNx) in the rat on both cardiac L-type Ca(2+) currents and action potential duration.

METHODS

Wistar rats underwent two-stage SNx; control rats (C) underwent bilateral renal decapsulation. Animals were sacrificed after 8 weeks, and ventricular myocytes were isolated. SNx rats showed a 2-fold increase in plasma urea and creatinine compared with C rats. Whole-cell patch clamp techniques were used to examine L-type Ca(2+) channel currents in isolated cardiac myocytes at 37 degrees C. In separate experiments, the epicardial monophasic action potentials of isolated perfused whole hearts from C and SNx rats were recorded.

RESULTS

The amplitude and current-voltage relationships of the L-type Ca(2+) current were not significantly different in myocytes from C (n=11) and SNx (n=8) rats. However, the rate of inactivation of the Ca(2+) current was increased by approximately 15-25% (P<0. 05) in myocytes from SNx rats. The action potential duration (APD(33)) at the apex of the left ventricle was approximately 20% shorter (P<0.01) in hearts from SNx rats as compared with controls.

CONCLUSIONS

Renal failure is associated with rapid inactivation of cardiac ventricular myocyte L-type Ca(2+) currents, which may reduce Ca(2+) influx and contribute to shortening of the action potential duration.

Volatile anesthetics increase intracellular calcium in cerebrocortical and hippocampal neurons

BACKGROUND

An increase in intracellular calcium concentration ([Ca2+]i) in neurons has been proposed as an important effect of volatile anesthetics, because they alter signaling pathways that influence neurotransmission. However, the existing data for anesthetic-induced increases in [Ca2+]i conflict.

METHODS

Changes in [Ca2+]i were measured using fura-2 fluorescence spectroscopy in rat cortical brain slices at 90, 185, 370, and 705 microM isoflurane. To define the causes of an increase in [Ca2+]i, slices were studied in Ca2+-free medium, in the presence of Ca2+-channel blockers, and in the presence of the Ca2+-release inhibitor azumolene. The authors compared the effect of the volatile anesthetic with that of the nonanesthetic compound 1,2-dichlorohexafluorocyclobutane. Single-dose experiments in CA1 neurons in hippocampal slices with halothane (360 microM) and in acutely dissociated CA1 neurons with halothane (360 microM) and isoflurane (445 microM) also were performed.

RESULTS

Isoflurane at 0.5, 1, and 2 minimum alveolar concentrations increased basal [Ca2+]i in cortical slices in a dose-dependent manner (P < 0.05). This increase was not altered by Ca2+-channel blockers or Ca2+-free medium but was reduced 85% by azumolene. The nonanesthetic 1,2-dichlorohexafluorocyclobutane did not increase [Ca2+]i. In dissociated CA1 neurons, isoflurane reversibly increased basal [Ca2+]i by 15 nM (P < 0.05). Halothane increased [Ca2+]i in dissociated CA1 neurons and CA1 neurons in hippocampal slices by approximately 30 nM (P < 0.05).

CONCLUSIONS

(1) Isoflurane and halothane reversibly increase [Ca2+]i in isolated neurons and in neurons within brain slices. (2) The increase in [Ca2+]i is caused primarily by release from intracellular stores. (3) Increases in [Ca2+]i occur with anesthetics but not with the nonanesthetic 1,2-dichlorohexafluorocyclobutane.