Influence of serum epidermal growth factor on mechanical ventilation and survival in patients with acute respiratory distress syndrome

How does blood glucose control with metformin influence intensive insulin protocols? Evidence for involvement of oxidative stress and inflammatory cytokines

INTRODUCTION

Recent investigations have revealed that control of hyperglycaemia with insulin improves outcomes. The cornerstone of hyperglycaemia in critically ill patients is insulin resistance and it remains refractory to intensive insulin protocols. We designed this study to evaluate the efficacy and safety of a new intensive insulin therapy (IIT) protocol combined with metformin.

METHODS

Twenty-one patients with systemic inflammatory response syndrome and a blood glucose level of >120 mg/dl admitted to an intensive care unit (ICU) were randomised to receive either intravenous infusion of IIT alone (n=11) or combined with metformin (IIT+MET; n=10) to maintain a blood glucose level (BGL) of 80-120 mg/dl. Blood samples were obtained at baseline and at 48 hours, 96 hours and 7 days after initiation of the study. Samples were analysed for interleukin-6 (IL-6), tumour necrosis factor alpha (TNF-alpha) and nitric oxide (NO) as inflammatory mediators; plasminogen activation inhibitor-1 (PAI-1) as a coagulation mediator; and thiobarbituric reactive substances (TBARS), total antioxidant power (TAP) and total thiol molecules (TTM) as oxidative stress parameters.

RESULTS

The addition of metformin to the IIT protocol decreased insulin requirement and concentration of insulin and C-peptide. With both treatments at most time points, the mean plasma levels of IL-6, TNF-alpha, NO, PAI-1 and TBARS were found to be significantly lower compared with baseline. Antioxidant activity was increased in both arms with increasing TAP and TTM (P<0.05). There was no significant difference between the two groups regarding reported beneficial effects on these parameters. Therapeutic Intervention Scoring System-28 (TISS-28) score, an index of nursing workload and number of therapeutic interventions, decreased in the IIT+MET group (P<0.01). We did not observe any occurrence of hyperlactataemia or acidosis in the IIT+MET group.

CONCLUSION

Metformin plus insulin appears to lower the incidence of insulin resistance, lower insulin requirement while maintaining blood glucose level control, and consequently lower the incidence of adverse effects related to high-dose insulin therapy, particularly hypoglycaemia, and also declined nursing workload. Both treatment protocols showed improvements in inflammatory cytokine levels. Further studies with larger sample sizes are warranted to determine the undiscovered facts of insulin-sensitising agents in critically ill patients.

Improvement by N-acetylcysteine of acute respiratory distress syndrome through increasing intracellular glutathione, and extracellular thiol molecules and anti-oxidant power: evidence for underlying toxicological mechanisms

In acute respiratory distress syndrome (ARDS), there is extensive overproduction of free radicals to the extent that endogenous anti-oxidants are overwhelmed, permitting oxidative cell damage. The present study examined the benefit of the anti-oxidant compound N-acetylcysteine (NAC) in the management of ARDS by measuring patient's intracellular glutathione (inside red blood cells) and extracellular (plasma) anti-oxidant defense biomarkers and outcome. Twenty-seven ARDS patients were recruited from the intensive care unit of a teaching Hospital and randomly divided into two groups. Both groups were managed similarly by regular treatments but 17 patients received NAC 150 mg/kg at the first day that followed by 50 mg/kg/day for three days and 10 patients did not receive NAC. Treatment by NAC increased extracellular total anti-oxidant power and total thiol molecules and also improved intracellular glutathione and the outcome of the patients. In conclusion, patients with ARDS are in a deficient oxidant-anti-oxidant balance that can get a significant benefit if supplemented with NAC.