Critical Care and Shock

Review

Clevidipine: A Unique Agent for the Critical Care Practitioner

Clevidipine is a new third generation intravenous dihydropyridine calcium channel blocker. It is a specific arterial vasodilator developed for the acute reduction and control of arterial blood pressure in the perioperative period. This drug has an extremely short half life and is rapidly metabolized by tissue and plasma esterases. Clevidipine is a potent arterial vasodilator with very little or no effect of the myocardial contractility and venous capacitance and also minimal side effects. Clevidipine can also theoretically help to protect against organ reperfusion injury.

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IABP deployment in critical care

The Intra Aortic Balloon Pump (IABP) is an established support in addition to pharmacologic treatment of the failing heart after myocardial infarction, unstable angina, cardiac surgery and percutaneous coronary intervention (PCI). The indication for IABP in acute myocardial infarction expanded to include support of severely ill patient during acute cardiac catheterization and myocardial revascularization both percutaneous and surgical. An international randomized trial, SHould we emergently revascularized Occluded Coronaries for cardiogenic shocK?

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Lactate is the ultimate oxidative energy substrate in brain and elsewhere

Now-a-days, the focus on lactate is due to its being an oxidative substrate for energy metabolism in brain (and other tissues), rather than a useless end product of anaerobic glycolysis. Mounting evidence indicates that lactate does play a major role in aerobic energy metabolism in the brain, the heart, skeletal muscle and possibly in any other tissue and organ.

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Spontaneous breathing during mechanical ventilation in ARDS

The objective of mechanical ventilation used in the management of Acute Respiratory Distress Syndrome (ARDS) is to ensure adequate tissue oxygenation and alveolar ventilation while limiting the patients’ work of breathing and preventing further damage to the lungs. Although the “partial support” ventilation modes were initially developed to assist weaning or liberation from supported ventilation, they have gained increasing popularity as primary ventilation modes, even in patients in with severe acute pulmonary dysfunction.

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Is there any need for higher PEEP levels in ARDS patients?

Lung protective ventilation has been shown to reduce mortality in ARDS patients. Current guidelines are focussed on lowering tidal volumes and minimizing mean airway pressures. In this review we discuss possible future improvements to mechanical ventilation; especially the open lung maneuver. We discuss the rationale for the use of higher PEEP levels in ARDS patients, using data from animal and human studies. Finally, guidelines for future strategies and/ or investigations are presented.

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Fluid resuscitation: the good, the bad and the ugly

Fluid resuscitation is one of the most common therapeutic steps in the critically ill. In this brief overview, the goals and potential adverse effects of fluid resuscitation are addressed. The contention is that the value of many of the fluid resuscitation goals in hypovolemic patients has not been unequivocally established, that overhydration is a significant problem and that certain types of fluids can be associated with major adverse effects.

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Pyrexia in the critically ill

Temperature change is a conserved physiological response to infection. In animal studies cytokine responses associated with body temperature changes have been elucidated. In humans with sepsis, hypothermia appears to be associated with higher TNF-alpha concentrations and has a significantly higher mortality. However, the presence of pyrexia does not appear to influence outcome from infection.

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Hypoxic tissue damage and the protective effects of therapeutic hypothermia

Several molecules, chemicals and cells are involved in tissue damage during any hypoxic event, such as a cardiac arrest, a respiratory arrest or a cerebrovascular accident. Among them: calcium, protein kinase enzymes, calcium binding proteins, S-100â protein and adhesion molecules such as intracellular adhesion molecule-1 (ICAM-1) are frequently cited in the literature. Controversy exists as to whether these “hypoxic aggressors” can be modified favorably by the use of therapeutic hypothermia.

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Life-threatening hyponatremia in marathon runners: The Varon-Ayus syndrome revisited

Life-threatening hyponatremia can occur when sodium concentration falls to 125 mmol/L or less. Symptoms usually do not depend on the absolute sodium concentration but on the rate of fall. Estimates of mortality in acute hyponatremia are as high as 50%. Marathon runners are at particular risk of developing a syndrome which consists of severe hyponatremia, pulmonary edema and cerebral edema as originally described by Varon and Ayus. This syndrome, if not managed appropriately has a very high morbidity and mortality.

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Continuous renal replacement therapy in intensive care unit

Acute renal failure (ARF) requiring dialysis is a common complication of patients in intensive care unit (ICU). Dialysis can be performed with either intermittent hemodialysis (IHD) or continuous renal replacement therapy (CRRT). CRRT is associated with less hemodynamic instability. Therefore, it is preferred in critically ill and hypotensive patients in ICU. However, current evidence does not demonstrate the superiority of CRRT over IHD.

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