Effects of ultrafiltration, dialysis, and temperature on gas exchange during hemodiafiltration: a laboratory experiment

Nutritional management in the critically ill child with acute kidney injury: a review

Acute kidney injury (AKI) in critically ill children is frequently a component of the multiple organ failure syndrome. It occurs within the framework of the severe catabolic phase determined by critical illness and is intensified by metabolic derangements. Nutritional support is a must for these children to improve outcomes. Meeting the special nutritional needs of these children often requires nutritional supplementation by either the enteral or the parenteral route. Since critically ill children with AKI comprise a heterogeneous group of subjects with varying nutrient needs, nutritional requirements should be frequently reassessed, individualized and carefully integrated with renal replacement therapy. This article is a state-of-the-art review of nutrition in critically ill children with AKI.

Indirect Calorimetry: A Practical Guide for Clinicians

This review provides clinicians with a comprehensive overview of indirect calorimetry including the principles, methodology, technologic advancements, benefits, and challenges. Clinical applications for indirect calorimetry and the potential limitations are specifically addressed for both the inpatient and outpatient setting. Measurement of energy expenditure is the most accurate method to assess energy needs. Indirect calorimetry remains a gold standard in measuring energy expenditure in the clinical settings. The benefits of providing optimal nutrition for recovery from illness and chronic health management are well documented. Indirect calorimetry offers a scientifically-based approach to customize a patient's energy needs and nutrient delivery to maximize the benefits of nutrition therapy. With recent advances in technology, indirect calorimeters are easier to operate, more portable, and affordable. Increased utilization of indirect calorimetry would facilitate individualized patient care and should lead to improved treatment outcomes.

Effects of continuous venovenous haemofiltration-induced cooling on global haemodynamics, splanchnic oxygen and energy balance in critically ill patients

BACKGROUND

A number of haemodialysis studies have demonstrated beneficial effects of cooler dialysates on global haemodynamics in chronic dialysis patients. However, the effects of continuous venovenous haemofiltration (CVVH)-induced cooling on regional perfusion and energy metabolism in critically ill septic patients have not been well defined.

METHODS

Nine septic mechanically ventilated patients (age 40-69 years) were investigated during CVVH (ultrafiltration 30-35 ml/kg/h). Baseline data (=WARM 1) were collected when core temperature (Tc) was >37.5 degrees C; the second data set (=COLD) was obtained after 120 min of 'cooling'; and a third set (=WARM 2) was obtained after 120 min of 'rewarming'. During 'warming' (WARM 1 and 2, respectively), both substitution fluids (SFs) and 'returned' blood (RB) were warmed (37 degrees C), whereas during 'cooling', the SFs were at 20 degrees C and RB was not warmed. We measured hepatic venous (HV) haemoglobin oxygen saturation (ShvO(2)), blood gases, lactate and pyruvate. Gastric mucosal PCO(2) (PgmCO(2)) was measured by air tonometry and the gastric mucosal - arterial PCO(2) difference (PCO(2) gap) was calculated. Haemodynamic monitoring was performed with arterial and pulmonary arterial thermodilution catheters.

RESULTS

Tcs were significantly altered [WARM 1, 37.9 degrees C (37.6, 38.3); COLD, 36.8 degrees C (36.3, 37.1); WARM 2, 37.5 degrees C (37.0, 38.0); P<0.001; data are median, 25th and 75th percentiles, respectively]. Systemic vascular resistance significantly increased during cooling. As a result, mean arterial pressure increased. Cooling was associated with significant decreases in heart rate, cardiac output, systemic oxygen delivery and consumption. ShvO(2) did not change [WARM 1, 51.0% (44.0, 59.5); COLD, 49.0% (42.0, 58.0); WARM 2, 51.0% (46.0, 57.0); P = NS]. The splanchnic oxygen extraction ratio, the HV lactate to pyruvate ratio, HV acid base status and PCO(2) gap remained unchanged.

CONCLUSION

Mild core cooling induced by CVVH may not affect hepatosplanchnic oxygen and energy balance in septic critically ill patients, even though it affects global haemodynamics.