Category Archives: Concise Critical Appraisal

Cellular Mechanisms of Prevention of Ischemia-Reperfusion Injury

Ischemic preconditioning is the phenomenon whereby brief periods of sublethal ischemia protect against a subsequent, more prolonged, ischemic insult. In remote ischemic preconditioning, ischemia to one organ protects other organs at a distance. Olenchock et al created mouse models to ask if inhibition of the alpha-ketoglutarate-dependent dioxygenase Egln1, which senses oxygen and regulates the hypoxia-inducible factor transcription factor, could suffice to mediate local and remote ischemic preconditioning.

Using somatic gene deletion and a pharmacological inhibitor, they found that inhibiting Egln1 systemically or in skeletal muscles protects mice against myocardial ischemia-reperfusion injury.

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Dysbiosis Across Multiple Body Sites in Critically Ill Adult Surgical Patients

Current evidence suggests that symbiosis of commensal microflora play a significant role in health and illness. The effect that commensal microflora play in critical care is less well known. Yeh et al set out to assess the dynamics of colonization of critically ill surgical and trauma patients. The authors examined 32 critically ill surgical and trauma patients in a major tertiary care intensive care unit (ICU) and collected information on bacterial colonization at gastrointestinal, tracheal, urinary, oral, and skin sites.

Over the course of the study (and in comparison to healthy controls) colonization in the ICU group showed a decrease in diversity of microflora across multiple sites and a change in colonization from non-pathogenic to pathogenic bacteria.

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Long-Term Quality of Life Among Survivors of Severe Sepsis

Severe sepsis currently accounts for 10% of all intensive care unit admissions and is the leading cause of death in U.S. hospitals. Studies have shown that sepsis survivors suffer from many long-term after-effects. Among survivors, mobility and the ability to perform daily activities tend to be limited and are used as markers of quality of life (QoL). However, these prior studies have been small and have not taken into account high burdens of chronic disease prior to sepsis admission. A study conducted by Yende et al is a secondary analysis of two international, randomized clinical trials (A Controlled Comparison of Eritoran and placebo in patients with Severe Sepsis [ACCESS] and PROWESS-SHOCK), with the aim of describing QoL in sepsis survivors. The two cohorts analyzed included only adults with severe sepsis who were fully functional and living at home prior to sepsis hospitalization.

They found that approximately one-third of patients (as described above) who survived hospitalization for severe sepsis had died at six months. A further one-third had not returned to independent living by six months.

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Intensive BP Lowering in Patients with Acute Cerebral Hemorrhage

Limited data are available to guide the choice of a target for the systolic blood-pressure level when treating acute hypertensive response in patients with intracerebral hemorrhage. Qureshi et al therefore randomly assigned eligible participants with intracerebral hemorrhage and a Glasgow Coma Scale score of five or more to a systolic blood-pressure target of 110 to 139 mm Hg (intensive treatment) or a target of 140 to 179 mm Hg (standard treatment) in order to test the superiority of intensive reduction of systolic blood pressure to standard reduction.

They found that the treatment of participants with intracerebral hemorrhage to achieve a target systolic blood pressure of 110 to 139 mm Hg did not result in a lower rate of death or disability than standard reduction to a target of 140 to 179 mm Hg.

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The Efficacy of Platelet Transfusion

Platelet transfusion after acute spontaneous primary intracerebral hemorrhage in people taking antiplatelet therapy might reduce death or dependence by reducing the extent of the hemorrhage. Baharoglu et al therefore aimed to investigate whether platelet transfusion with standard care, compared with standard care alone, reduced death or dependence after intracerebral hemorrhage associated with antiplatelet therapy use.

They found that platelet transfusion seems inferior to standard care for people taking antiplatelet therapy before intracerebral hemorrhage.

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Sedatives and Their Associations with VAEs and Time to Extubation

Sedative selection is crucial to outcomes in critically ill patients. While benzodiazepines are known to be associated with a longer duration of mechanical ventilation compared to propofol and dexmedetomidine, little data exist comparing these sedatives in association with ventilator-associated events (VAEs). Klompas et al therefore aimed to evaluate the association between these sedatives, VAEs and time to extubation.

They found that sedatives vary in their associations with VAEs and time to extubation but not in their associations with time to hospital discharge or mortality.

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Peak Lactate and Patient Outcome Following High-Risk Gastrointestinal Surgery

The association between hyperlactatemia and adverse outcome in patients admitted to intensive care units (ICUs) following gastrointestinal surgery has not been reported. Creagh-Brown et al therefore set out to explore the hypothesis that in a large cohort of gastrointestinal surgical patients, the peak serum lactate (in the first 24 hours) observed in patients admitted to the ICU following surgery is associated with unadjusted and severity-adjusted acute hospital mortality and that the strength of association is greater in patients admitted following emergency surgery than in patients admitted following elective surgery.

They found that elevated lactate is independently associated with in-hospital mortality in the postoperative gastrointestinal surgical patient and is no less significant in the context of elective surgery.

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Delirium and the Efficacy of Dexmedetomidine

Some contend that effective therapy has not been established for patients with agitated delirium receiving mechanical ventilation. Therefore, Reade et al set out to determine the effectiveness of dexmedetomidine when added to standard care in patients with agitated delirium receiving mechanical ventilation.

They found that among patients with agitated delirium receiving mechanical ventilation in the intensive care unit, the addition of dexmedetomidine to standard care (compared with standard care alone [placebo]) resulted in more ventilator-free hours at seven days.

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Use of High-Flow Oxygen Therapy in Low-Risk Postextubation Patients

Studies of mechanically ventilated critically ill patients that combine populations that are at high and low risk for reintubation suggest that conditioned high-flow nasal cannula oxygen therapy after extubation improves oxygenation compared with conventional oxygen therapy. However, conclusive data about reintubation are lacking. Therefore, Hernández et al set out to determine whether high-flow nasal cannula oxygen therapy is superior to conventional oxygen therapy for preventing reintubation in mechanically ventilated patients at low risk for reintubation.

They found that among extubated patients at low risk for reintubation, the use of high-flow nasal cannula oxygen compared with conventional oxygen therapy reduced the risk of reintubation within 72 hours.

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Predicting Fluid Responsiveness by Passive Leg Raising

Passive leg raising creates a reversible increase in venous return, allowing for the prediction of fluid responsiveness. However, the amount of venous return may vary in various clinical settings, potentially affecting the diagnostic performance of passive leg raising. Therefore, Cherpanath et al performed a systematic meta-analysis determining the diagnostic performance of passive leg raising in different clinical settings with exploration of patient characteristics, measurement techniques and outcome variables.

They found that passive leg raising retains a high diagnostic performance in various clinical settings and patient groups. They also found that the predictive value of a change in pulse pressure on passive leg raising is inferior to a passive leg raising-induced change in a flow variable.

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Higher Versus Lower Blood Pressure Targets for Vasopressor Therapy in Shock

In shock, hypotension may contribute to inadequate oxygen delivery, organ failure and death. Lamontagne et al conducted the Optimal Vasopressor Titration (OVATION) pilot trial to inform the design of a larger trial examining the effect of lower versus higher mean arterial pressure (MAP) targets for vasopressor therapy in shock.

They concluded that their pilot study supports the feasibility of a large trial comparing lower versus higher MAP targets for shock. Further research may help delineate the reasons for vasopressor dosing in excess of prescribed targets and how individual patient characteristics modify the response to vasopressor therapy.

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Rate Control vs. Rhythm Control for Atrial Fibrillation after Cardiac Surgery

Atrial fibrillation continues to plague intensivists managing post-cardiac surgery patients. Large clinical trials in non-surgical populations have demonstrated that rhythm control offers no benefits over a simpler rate control strategy. However, it is unclear if these findings can be extrapolated to the post-cardiac surgical population. As such, Gillinov et al conducted a randomized controlled trial hoping to answer this very question.

They found that strategies for rate control and rhythm control to treat post-operative atrial fibrillation were associated with equal numbers of days of hospitalization, similar complication rates and similarly low rates of persistent atrial fibrillation 60 days after onset.

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Chronic Hypoxemia in Children with CHD Mars Airway Epithelial Na+ Transport

Ambient hypoxia impairs the airway epithelial Na+ transport, which is crucial in lung edema reabsorption. Whether chronic systemic hypoxemia affects airway Na+ transport has remained largely unknown. Kaskinen et al have therefore investigated whether chronic systemic hypoxemia in children with congenital heart defect affects airway epithelial Na+ transport, Na+ transporter-gene expression, and short-term lung edema accumulation.

They found that the impaired airway epithelial amiloride-sensitive Na+ transport activity in profoundly hypoxemic children with cyanotic congenital heart defect may hinder defense against lung edema after cardiac surgery.

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Expediting Transfer of Patients with Time-Sensitive Critical Illness

Time-sensitive, critical surgical illnesses require care at specialized centers. Trauma systems facilitate patient transport to designated trauma centers, but formal systems for nontraumatic critical illness do not exist. Scalea et al created the critical care resuscitation unit to expedite transfers of adult critically ill patients with time-sensitive conditions to a quaternary academic medical center, hypothesizing that this would decrease time to transfer, increase transfer volume, and improve outcomes.

They found that the critical care resuscitation unit dramatically increased the volume of critically ill surgical patients. It decreased transfer times, increased volume, and, for those who required urgent operation, decreased time from initial referral to the operating room.

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Risk Factors for Readmission for Sepsis Survivors

Hospital readmission is common after sepsis, yet the relationship between the index admission and readmission remains poorly understood. Sun et al sought to examine the relationship between infection during the index acute care hospitalization and readmission and to identify potentially modifiable factors during the index sepsis hospitalization associated with readmission.

They confirmed that the majority of unplanned hospital readmissions after sepsis are due to an infection. They also found that patients with sepsis at admission who developed a hospital-acquired infection, and those who received a longer duration of antibiotics, appear to be high-risk groups for unplanned, all-cause 30-day readmissions and infection-related 30-day readmissions.

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