Ammonia and nutritional therapy in the critically ill: when to worry, when to test and how to treat?

PURPOSE OF REVIEW: Hyperammonaemia is almost always develops in patients with severe liver failure and this remains the commonest cause of elevated ammonia concentrations in the ICU. Nonhepatic hyperammonaemia in ICU presents diagnostic and management challenges for treating clinicians. Nutritional and metabolic factors play an important role in the cause and management of these complex disorders. RECENT FINDINGS: Nonhepatic hyperammonaemia causes such as drugs, infection and inborn errors of metabolism may be unfamiliar to clinicians and risk being overlooked. Although cirrhotic patients may tolerate marked elevations in ammonia, other causes of acute severe hyperammonaemia may result in fatal cerebral oedema. Any coma of unclear cause should prompt urgent measurement of ammonia and severe elevations warrant immediate protective measures as well as treatments such as renal replacement therapy to avoid life-threatening neurological injury. SUMMARY: The current review explores important clinical considerations, the approach to testing and key treatment principles that may prevent progressive neurological damage and improve outcomes for patients with hyperammonaemia, especially from nonhepatic causes.

Functional electrical stimulation with cycling in the critically ill: a pilot case-matched control study.

PURPOSE: The purpose was to determine (a) safety and feasibility of functional electrical stimulation (FES)-cycling and (b) compare FES-cycling to case-matched controls in terms of functional recovery and delirium outcomes. MATERIALS AND METHODS: Sixteen adult intensive care unit patients with sepsis ventilated for more than 48 hours and in the intensive care unit for at least 4 days were included. Eight subjects underwent FES-cycling in addition to usual care and were compared to 8 case-matched control individuals. Primary outcomes were safety and feasibility of FES-cycling. Secondary outcomes were Physical Function in Intensive Care Test scored on awakening, time to reach functional milestones, and incidence and duration of delirium. RESULTS: One minor adverse event was recorded. Sixty-nine out of total possible 95 FES sessions (73%) were completed. A visible or palpable contraction was present 80% of the time. There was an improvement in Physical Function in Intensive Care Test score of 3.9/10 points in the intervention cohort with faster recovery of functional milestones. There was also a shorter duration of delirium in the intervention cohort. CONCLUSIONS: The delivery of FES-cycling is both safe and feasible. The preliminary findings suggest that FES-cycling may improve function and reduce delirium. Further research is required to confirm the findings of this study and evaluate the efficacy of FES-cycling.

Pilot randomised double-blind controlled trial of high-dose spironolactone in critically ill patients receiving a frusemide infusion.

BACKGROUND: Hypernatraemia may develop during intravenous infusion of frusemide. Spironolactone is an aldosterone antagonist that promotes natriuresis and may attenuate such hypernatraemia, but its effect in this setting has not been previously studied. OBJECTIVE: To assess whether the administration of spironolactone to ventilated patients receiving a frusemide infusion attenuates the increase in serum sodium concentration. DESIGN AND SETTING: Randomised, double-blind, placebo-controlled trial (January 2005 to December 2006). PATIENTS: 20 patients with a serum creatinine concentration < 300 micromol/L who were undergoing mechanical ventilation in the intensive care unit and had begun a frusemide infusion as treatment for fluid overload within the previous 24 hours. METHODS: Patients were randomly allocated to receive either spironolactone (100 mg three times daily) or placebo by nasogastric tube for the duration of the frusemide infusion. Daily serum levels of urea and creatinine, 24-hour urine sodium and potassium levels, fluid balance and 24- hour blood levels of aldosterone, human atrial natriuretic peptide and plasma renin activity were measured throughout the period of frusemide infusion. RESULTS: Change in serum sodium concentration over 48 hours from baseline was 3.0 mmol/L for placebo versus 1.0 mmol/L for the spironolactone group (P = 0.08). Change in serum potassium concentration did not differ between the groups (0.125 mmol/L over 48 hours). There were no significant differences in total urinary sodium or potassium excretion. Serum creatinine, urea, urine volume, fluid balance, potassium requirements and hormone levels were similar in both groups. CONCLUSIONS: In this pilot study, the administration of high-dose spironolactone to ventilated critically ill patients receiving frusemide by infusion had no significant effects on serum sodium level, natriuresis or potassium balance when compared with placebo.