High energy deficits due to underfeeding are frequently observed during critical illness and are associated with significant morbidity and mortality. Adequate determination of energy requirements is imperative for optimizing nutrition. For this goal, indirect calorimetry is considered to be the gold standard but it is expensive, time-consuming, and not readily available in many hospitals. As an alternative, most ICU physicians use bedside formulas to predict calorie needs. Some equations are obtained during resting metabolism in healthy humans and “corrected” by adding stress or injury factors. Others are derived from regression analysis in patients whereby various static and dynamic variables are identified and eventually adjusted for type of patient and/or disease. Few studies have evaluated the accuracy of predictive equations in critically ill patients. The largest prospective study to date identified the Penn State equation, including a modified version for obesity, as being the most accurate. Whether the systematic use of (a) particular formula(s) for estimating calorie needs may influence morbidity or outcome in ICU patients remains to be determined.
Polymyxins are ‘‘old’’ antimicrobials which were abandoned for almost 30 years because of significant renal and neurological toxicity. However, the alarming rise of multi-resistant Gramnegative bacterial infections worldwide has revived interest in these ‘‘forgotten’’ agents. Colistin (polymyxin E) is one of the main antibiotics of this class. It is most often administered as the pro-drug colistimethate sodium. Doses for treatment of systemic infections in adults range between 3 and 9 million IU per day. Colistin is increasingly used for treatment of pneumonia and bacteremia in critically ill patients. During their ICU stay, many of these subjects will need continuous renal replacement therapy (CRRT) because of acute kidney injury or an unstable hemodynamic condition. Based on recent pharmacological data and own experience, we postulate that patients undergoing CRRT may receive substantially higher doses of colistin (i.e., a high loading dose, followed by a maintenance dose up to 4.5 million IU tid). Treatment can be continued for a prolonged time period without increasing toxicity. CRRT counteracts colistin accumulation because the drug is continuously filtered and also significantly adsorbed in the bulk of the dialysis membrane. Implementing such ‘‘CRRT rescue’’ therapy does require the strict use of highly adsorptive dialysis membranes in association with citrate anticoagulation to increase membrane performance.
Sepsis-induced acute kidney injury (SAKI) remains an important challenge for intensive care unit clinicians. We reviewed current available evidence regarding prevention and treatment of SAKI thereby incorporating some major recent advances and developments. Prevention includes early and ample administration of “balanced” crystalloid solutions such as Ringer’s lactate. For monitoring of renal function during resuscitation, lactate clearance rate is preferred above ScvO2 or renal Doppler. Aiming at high central venous pressures seems to be deleterious in light of the novel “kidney afterload” concept. Noradrenaline is the vasopressor of choice for preventing SAKI. Intra-abdominal hypertension, a potent trigger of acute kidney injury in postoperative and trauma patients, should not be neglected in sepsis. Renal replacement therapy (RRT) must be started early in fluid-overloaded patients refractory to diuretics. Continuous RRT (CRRT) is the preferred modality in hemodynamically unstable SAKI but its use in more stable SAKI is increasing. In the absence of hypervolemia, diuretics should be avoided. Antimicrobial dosing during CRRT needs to be thoroughly reconsidered to assure adequate infection control.
Statins essentially are cholesterol-lowering drugs that are extensively prescribed for primary and secondary prevention of cardiovascular disease. Compelling evidence suggests that the beneficial effects of statins may not only be due to its ability to control cholesterol levels but also due to a pleiotropic cholesterol-independent anti-inflammatory, antioxidant, endothelial-protective and plaque-stabilizing activity. Along this line, statins may also exert acute and long-term effects on renal function. We present a narrative literature review that summarizes arguments in favor of or against the preventive and/or therapeutic use of statins in kidney-related diseases or complications. We also highlight the ongoing controversy regarding statin therapy in chronic and end-stage kidney disease.