The critical care literature 2020.

Given the dramatic increase in critically ill patients who present to the emergency department for care, along with the persistence of boarding of critically ill patients, it is imperative for the emergency physician to be knowledgeable about recent developments in resuscitation and critical care medicine. This review summarizes important articles published in 2020 that pertain to the resuscitation and care of select critically ill patients. These articles have been selected based on the authors annual review of key critical care, emergency medicine and medicine journals and their opinion of the importance of study findings as it pertains to the care of critically ill ED patients. Several key findings from the studies discussed in this paper include the administration of dexamethasone to patients with COVID-19 infection who require mechanical ventilation or supplemental oxygen, the use of lower levels of positive end-expiratory pressure for patients without acute respiratory distress syndrome, and early initiation of extracorporeal membrane oxygenation for out-of-hospital cardiac arrest patients with refractory ventricular fibrillation if resources are available. Furthermore, the emergency physician should not administer tranexamic acid to patients with acute gastrointestinal bleeding or administer the combination of vitamin C, thiamine, and hydrocortisone for patients with septic shock. Finally, the emergency physician should titrate vasopressor medications to more closely match a patient's chronic perfusion pressure rather than target a mean arterial blood pressure of 65 mmHg for all critically ill patients.

Neurovascular unit and the effects of dosage in VEGF toxicity: role for oxidative stress and thrombin.

Bidirectional communication between neurons and vascular cells is important to the maintenance of the central nervous system (CNS) milieu. Vascular endothelial growth factor (VEGF), through its ability to affect both vascular and neuronal cells, is likely a key protein in this process. Despite considerable literature documenting a neuroprotective function for VEGF, overexpression of this protein has also been shown in a wide variety of CNS diseases, including Alzheimer's disease (AD). Increased oxidative stress and elevated thrombin levels have also been documented in AD, specifically in the microvasculature. The aim of the current study is to examine endothelial cells and neurons in vitro to determine the effects of oxidative stress and thrombin on VEGF release as well as the effects of low and high dose VEGF on neuronal viability. The data show that microvessels isolated from AD patients secrete significantly higher levels of VEGF compared to control-derived vessels. Exposure of brain endothelial cells to oxidative stress (sodium nitroprusside, menadione, or hydrogen peroxide) or thrombin significantly increases VEGF expression. Exposure of cultured neurons to oxidative stress increases expression of thrombin. Treating rat cortical neurons with high dose VEGF (≥500 ng/ml) decreases neuronal survival and expression of the anti-apoptotic protein Bcl-2 while increasing proapoptic proteins caspase 3 and phosphorylated p38 MAPK. High dose VEGF also negates the decrease in amyloid-ß evoked by low dose VEGF. These results suggest that despite literature supporting neuroprotective effects of this protein, caution is warranted prior to implementation of VEGF as a therapeutic in the brain.

Dietary uridine enhances the improvement in learning and memory produced by administering DHA to gerbils.

This study examined the effects on cognitive behaviors of giving normal adult gerbils three compounds, normally in the circulation, which interact to increase brain phosphatides, synaptic proteins, dendritic spines, and neurotransmitter release. Animals received supplemental uridine (as its monophosphate, UMP; 0.5%) and choline (0.1%) via the diet, and docosahexaenoic acid (DHA; 300 mg/kg/day) by gavage, for 4 wk, and then throughout the subsequent period of behavioral training and testing. As shown previously, giving all three compounds caused highly significant (P<0.001) increases in total brain phospholipids and in each major phosphatide; giving DHA or UMP (plus choline) produced smaller increases in some of the phosphatides. DHA plus choline improved performance on the four-arm radial maze, T-maze, and Y-maze tests; coadministering UMP further enhanced these increases. (Uridine probably acts by generating both CTP, which can be limiting in phosphatide synthesis, and UTP, which activates P2Y receptors coupled to neurite outgrowth and protein synthesis. All three compounds also act by enhancing the substrate-saturation of phosphatide-synthesizing enzymes.) These findings demonstrate that a treatment that increases synaptic membrane content can enhance cognitive functions in normal animals.

Diminished renal kallikrein responses to mineralocorticoid stimulation in African Americans: determinants of an intermediate phenotype for hypertension.

BACKGROUND: Hypertension is a complex trait with an ill-defined genetic predisposition, in which renal mechanisms seem to be involved even at the early stages. Renal kallikrein excretion is diminished in patients with hypertension, and perhaps even in the early, prehypertensive phases of the syndrome. African Americans, a group at increased risk of developing hypertension, have especially diminished kallikrein expression, coupled with decreased renal excretion of K(+), a known stimulant of kallikrein expression, suggesting an environmental mechanism for their kallikrein deficit. We, therefore, tested whether short-term indirect (K(+)) or direct (fludrocortisone) stimulation of mineralocorticoid activity might be capable of restoring kallikrein excretion in African Americans. METHODS: Nineteen healthy normotensive young men (n = 10 white, n = 9 African Americans) were treated with the following sequence of four oral medications, each for 1 week: placebo, KCl (120 mEq/day), placebo, and the mineralocorticoid fludrocortisone (0.4 mg/day). At each stage, we measured vital signs, excretion of kallikrein, aldosterone and electrolytes, and serum renin. Results were evaluated by two-way, repeated measures ANOVA. RESULTS: African Americans had diminished urinary excretion of not only kallikrein (P =.007), but also K(+) (P <.001) and aldosterone (P =.015). Kallikrein responses to mineralocorticoid stimulation were substantially blunted in African Americans, whether achieved indirectly (by supplemental K(+); P =.019) or directly (by the exogenous mineralocorticoid fludrocortisone; P =.027), despite achievement of substantial increments in K(+) excretion after KCl (P =.002), and multiple other mineralocorticoid effects after fludrocortisone (P =.005). The kallikrein increment after KCl was best predicted by renin activity (P =.001) rather than ethnicity. Potassium chloride did not lower blood pressure (BP) in either group (P >.4). CONCLUSIONS: Restoration of K(+) and aldosterone secretion to levels found in whites does not normalize kallikrein excretion or lower BP in African Americans, at least in the short term. Nor does exogenous mineralocorticoid stimulation fully restore kallikrein expression in African Americans. Therefore, the diminution of kallikrein biosynthesis in African Americans seems to involve mechanisms at or distal to the aldosterone receptor, and perhaps at the level of the kallikrein gene itself.