Best practice & research. Clinical anaesthesiology
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Best Pract Res Clin Anaesthesiol · Mar 2004
ReviewVascular access for dialysis in the intensive care unit.
Management of the vascular access (VA) for renal replacement therapy (RRT) in acute renal failure (ARF) patients is faced with a twofold problem: first, the creation of an angio-access that is adequate for RRT in the acute setting; second, the preservation of the patient's vascular network in order not to preclude further use of the vessel in the event of evolution to chronic renal failure. Central venous catheters are the preferred VA for RRT in the intensive care setting. Semi-rigid double-lumen polyurethane catheters may be considered for short-time use (up to 2-3 weeks). ⋯ Catheter handling and care should comply with best practice guidelines and should be part of a continuous quality improvement programme in order to reduce catheter-related morbidity. Preservation of the upper limb vascular network of the patient consists of sparing the native vessels (artery and vein) of the patient and preserving the functionality of the permanent VA in chronic renal failure patient. This 'lifeline' of chronic renal failure patients may be maintained by preventing inflammation, infection and thrombosis of the superficial vessels of the arm and forearm of patient.
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Best Pract Res Clin Anaesthesiol · Mar 2004
ReviewAcid-base balance in acute renal failure and renal replacement therapy.
The approach to acid-base balance based on the concept of strong ions, initially proposed by Stewart, is briefly overviewed. The anion gap and the strong anion gap are both discussed. ⋯ The consequences of renal metabolic acidosis are described. Finally, the impact of renal replacement therapy on acid-base balance is exposed; different modalities of renal replacement are considered in regard to their alkalinizing performance.
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Mechanical ventilation is a standard component of intensive care unit management of critically ill patients and is widely used for respiratory support. Recent animal and clinical studies have shown that positive pressure ventilation can worsen pre-existing lung injury and produce ventilator-induced lung injury, which has been linked with the development of systemic inflammation and multi-system organ dysfunction, including renal failure. ⋯ Interestingly, recent data are emerging which suggest that renal dysfunction also has a direct, adverse effect on pulmonary function. This chapter reviews the information in these areas and provides a framework for future investigation in this field.
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Protection of renal function and prevention of acute renal failure (ARF) are important goals of resuscitation in critically ill patients. Beyond fluid resuscitation and avoidance of nephrotoxins, little is known about how such prevention can be achieved. Vasoactive drugs are often administered to improve either cardiac output or mean arterial pressure in the hope that renal blood flow will also be improved and, thereby, renal protection achieved. ⋯ In the absence of such data, all that is available is based on limited physiological gains (changes in renal blood flow or urine output) with one or another drug in one or another subpopulation of patients. Furthermore, given our lack of understanding of the pathogenesis of ARF, it is unclear whether haemodynamic manipulation is an appropriate avenue to achieve renal protection. There is a great need for large randomized controlled trials to test the clinical, instead of physiological, effects of vasoactive drugs in critical illness.
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Because oliguria is a bad prognostic sign in patients with acute renal failure (ARF), diuretics are often used to increase urine output in patients with or at risk of ARF. From a pathophysiological point of view there are several reasons to expect that loop diuretics also could have a beneficial effect on renal function. However, clinical trials on the prophylactic use of loop diuretics rather point to a deleterious effect on parameters of kidney function. ⋯ On the other hand, such an effect cannot be excluded because the available trials lack statistical power. Possible explanations for the absence of a renoprotective effect are discussed. The evidence for a renoprotective effect of mannitol is restricted to the setting of renal transplantation.