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1.  Red blood cell transfusion in the critically ill patient 
Red blood cell (RBC) transfusion is a common intervention in intensive care unit (ICU) patients. Anemia is frequent in this population and is associated with poor outcomes, especially in patients with ischemic heart disease. Although blood transfusions are generally given to improve tissue oxygenation, they do not systematically increase oxygen consumption and effects on oxygen delivery are not always very impressive. Blood transfusion may be lifesaving in some circumstances, but many studies have reported increased morbidity and mortality in transfused patients. This review focuses on some important aspects of RBC transfusion in the ICU, including physiologic considerations, a brief description of serious infectious and noninfectious hazards of transfusion, and the effects of RBC storage lesions. Emphasis is placed on the importance of personalizing blood transfusion according to physiological endpoints rather than arbitrary thresholds.
doi:10.1186/2110-5820-1-43
PMCID: PMC3207872  PMID: 21970512
2.  Control of hypertension in the critically ill: a pathophysiological approach 
Severe acute arterial hypertension can be associated with significant morbidity and mortality. After excluding a reversible etiology, choice of therapeutic intervention should be based on evaluation of a number of factors, such as age, comorbidities, and other ongoing therapies. A rational pathophysiological approach should then be applied that integrates the effects of the drug on blood volume, vascular tone, and other determinants of cardiac output. Vasodilators, calcium channel blockers, and beta-blocking agents can all decrease arterial pressure but by totally different modes of action, which may be appropriate or contraindicated in individual patients. There is no preferred agent for all situations, although some drugs may have a more attractive profile than others, with rapid onset action, short half-life, and fewer adverse reactions. In this review, we focus on the main mechanisms underlying severe hypertension in the critically ill and how using a pathophysiological approach can help the intensivist decide on treatment options.
doi:10.1186/2110-5820-3-17
PMCID: PMC3704960  PMID: 23806076
Beta-blockers; Calcium channel blockers; Cardiac output; Diuretics; Mean arterial pressure; Vasodilators
3.  Urea for treatment of acute SIADH in patients with subarachnoid hemorrhage: a single-center experience 
Background
Hyponatremia occurring as a result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) or cerebral salt wasting syndrome is a common complication in patients with subarachnoid hemorrhage (SAH). The efficacy and safety of urea as treatment for SIADH-induced hyponatremia has not been reported in this population.
Methods
This is a retrospective analysis of all patients admitted to our department for nontraumatic SAH between January 2003 and December 2008 (n = 368). All patients with SIADH-induced hyponatremia (plasma sodium < 135 mEq/L, urine sodium > 20 mEq/L, and osmolality > 200 mOsm/kg; absence of overt dehydration or hypovolemia; no peripheral edema or renal failure; no history of adrenal or thyroid disease) routinely received urea per os when hyponatremia was associated with clinical deterioration or remained less than 130 mEq/L despite saline solution administration.
Results
Forty-two patients developed SIADH and were treated with urea. Urea was started after a median of 7 (IQR, 5–10) days and given orally at doses of 15–30 g tid or qid for a median of 5 (IQR, 3–7) days. The median plasma sodium increase over the first day of treatment was 3 (IQR, 1–6) mEq/L. Hyponatremia was corrected in all patients, with median times to Na+ >130 and >135 mEq/L of 1 (IQR, 1–2) and 3 (IQR, 2–4) days, respectively. Urea was well tolerated, and no adverse effects were reported.
Conclusions
Oral urea is an effective and well-tolerated treatment for SIADH-induced hyponatremia in SAH patients.
doi:10.1186/2110-5820-2-13
PMCID: PMC3488535  PMID: 22647340
Hyponatremia; SIADH; Sodium; Subarachnoid hemorrhage; Urea
4.  Microcirculatory alterations: potential mechanisms and implications for therapy 
Multiple experimental and human trials have shown that microcirculatory alterations are frequent in sepsis. In this review, we discuss the characteristics of these alterations, the various mechanisms potentially involved, and the implications for therapy. Sepsis-induced microvascular alterations are characterized by a decrease in capillary density with an increased number of stopped-flow and intermittent-flow capillaries, in close vicinity to well-perfused capillaries. Accordingly, the surface available for exchange is decreased but also is highly heterogeneous. Multiple mechanisms may contribute to these alterations, including endothelial dysfunction, impaired inter-cell communication, altered glycocalyx, adhesion and rolling of white blood cells and platelets, and altered red blood cell deformability. Given the heterogeneous nature of these alterations and the mechanisms potentially involved, classical hemodynamic interventions, such as fluids, red blood cell transfusions, vasopressors, and inotropic agents, have only a limited impact, and the microcirculatory changes often persist after resuscitation. Nevertheless, fluids seem to improve the microcirculation in the early phase of sepsis and dobutamine also can improve the microcirculation, although the magnitude of this effect varies considerably among patients. Finally, maintaining a sufficient perfusion pressure seems to positively influence the microcirculation; however, which mean arterial pressure levels should be targeted remains controversial. Some trials using vasodilating agents, especially nitroglycerin, showed promising initial results but they were challenged in other trials, so it is difficult to recommend the use of these agents in current practice. Other agents can markedly improve the microcirculation, including activated protein C and antithrombin, vitamin C, or steroids. In conclusion, microcirculatory alterations may play an important role in the development of sepsis-related organ dysfunction. At this stage, therapies to target microcirculation specifically are still being investigated.
doi:10.1186/2110-5820-1-27
PMCID: PMC3224481  PMID: 21906380

Results 1-4 (4)