Contributions to nephrology
-
The extracorporeal carbon dioxide removal (ECCO(2)R) concept, used as an integrated tool with conventional ventilation, plays a role in adjusting respiratory acidosis consequent to tidal volume (Vt) reduction in a protective ventilation setting. This concept arises from the extracorporeal membrane oxygenation (ECMO) experience. Kolobow and Gattinoni were the first to introduce extracorporeal support, with the intent to separate carbon dioxide removal from oxygen uptake; they hypothesized that to allow the lung to 'rest' oxygenation via mechanical ventilation could be dissociated from decarboxylation via extracorporeal carbon dioxide removal. ⋯ The future development of more and more efficient devices capable of removing a substantial amount of carbon dioxide production (30-100%) with blood flows of 250-500 ml/min is foreseeable. Moreover, in the future ARDS management should include a minimally invasive ECCO(2)R circuit associated with noninvasive ventilation. This would embody the modern mechanical ventilation philosophy: avoid tracheal tubes; minimize sedation, and prevent ventilator-induced acute lung injury and nosocomial infections.
-
Acute kidney injury (AKI) is a common complication of critical illness. While the etiology of AKI in critically ill patients is likely often multifactorial, sepsis has consistently been found an important contributing factor and has been associated with high attributable morbidity and mortality. Accordingly, the timely identification of septic AKI in critically ill patients is clearly a clinical priority. ⋯ In addition, several urinary biochemical tests, derived indices and microscopy have also been widely cited as valuable in the diagnosis and classification of AKI. However, the value of these urinary tests in the diagnosis, classification, prognosis and clinical management in septic AKI remains unclear, due in part to a lack of kidney morphologic changes and histopathology in human studies of septic AKI. This review will summarize the urinary biochemistry and microscopy in septic AKI.
-
Endotoxin removal by polymyxin B immobilized cartridge inactivates circulating proapoptotic factors.
Severe sepsis and septic shock continue to be major clinical challenges due to high associated mortality. Lipopolysaccharide (LPS) is a component of the cell membrane of Gram-negative bacteria, and is believed to initiate septic-induced signaling, inflammation and organ damage, including acute renal failure. Polymyxin B (PMX-B) hemoperfusion of septic patients can improve survival and decreasing organ dysfunction by removing circulating LPS. Unfortunately, some clinicians have been slow to adopt this novel therapy due to the lack of understanding of the cellular mechanisms involved in this treatment. Apoptosis, or programmed cell death, is known to contribute to acute renal failure and overall organ dysfunction during sepsis, and can be activated by LPS-initiated signaling pathways. Therefore, the protective renal effects associated with PMX-B hemoperfusion of septic patients may result from alterations in cellular apoptosis. This chapter will review recent data regarding the role of apoptosis prevention in the mechanism leading to the improved outcome and decreased acute renal failure associated with PMX-B hemoperfusion during sepsis. ⋯ The protective effects of extracorporeal therapy with PMX-B on the development of acute renal failure result, in part, through its ability to reduce the systemic proapoptotic activity of septic patients on renal cells.
-
Acute lung injury (ALI) and acute kidney injury (AKI) are complications often encountered in the setting of critical illness. Both forms of end-organ injury commonly occur in similar settings of systemic inflammatory response syndrome, shock, and evolving multiple organ dysfunction. Distant organ effects of apparently isolated injuries to the lungs, gut, and kidneys have all been discovered in recent years. In this review of the emerging evidence of deleterious bidirectional organ crosstalk between the lungs and kidney, we will focus on the role of ventilator-induced kidney injury in the pathogenesis of AKI in patients with ALI.
-
Blood purification in critical care can perform 2 main functions: as an artificial support for failing organs (such as artificial kidney or liver support) and as a remover of causative humoral mediators of critical illness (such as severe sepsis and acute respiratory distress syndrome). As an artificial kidney, continuous blood purification (such as continuous hemofiltration and continuous hemodiafiltration, CHDF) is widely applied in intensive care units. The intensity of renal replacement therapy, however, has been reported to have no impact upon the efficacy of the blood purification in terms of clinical outcome. ⋯ However, our understanding of the pathophysiology of sepsis has changed since the concept of pattern recognition receptors and pathogen-associated molecular patterns was introduced. According to this, CHDF with a cytokine-adsorbing polymethylmethacrylate membrane hemofilter is preferable and more effective than direct hemoperfusion with an endotoxin-adsorbing polymyxin-B immobilized column in the treatment of sepsis and septic shock. Blood purification in critical care is gaining popularity, and is widely for both renal and non-renal indications.