Category Archives: Concise Critical Appraisal

Examining Very Short Antibiotic Courses

Many patients started on antibiotics for possible ventilator-associated pneumonia (VAP) do not have pneumonia. Patients with minimal and stable ventilator settings may be suitable candidates for early antibiotic discontinuation. Therefore, Klompas et al set out to compare outcomes amongst patients with suspected VAP but minimal and stable ventilator settings treated with one to three versus more than three days of antibiotics.

Very short antibiotic courses (one to three days) were associated with outcomes similar to longer courses (more than three days) in patients with suspected VAP but minimal and stable ventilator settings.

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High-Flow Nasal Cannula vs. Noninvasive Ventilation

High-flow conditioned oxygen therapy delivered through nasal cannulae and noninvasive mechanical ventilation (NIV) may reduce the need for reintubation. Therefore, Hernández et al set out to test if high-flow conditioned oxygen therapy is noninferior to NIV for preventing postextubation respiratory failure and reintubation in patients at high risk of reintubation.

They found that among high-risk adults who have undergone extubation, high-flow conditioned oxygen therapy was not inferior to NIV for preventing reintubation and postextubation respiratory failure.

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Efficacy of Combined Intravenous Thrombolysis and Thrombectomy

Mechanical thrombectomy (MT) improves clinical outcomes in patients with acute ischemic stroke (AIS) caused by a large vessel occlusion. However, it is not known whether intravenous thrombolysis (IVT) is of added benefit in patients undergoing MT. Coutinho et al set out to address this unknown.

The results indicate that treatment of patients experiencing AIS due to a large vessel occlusion with IVT before MT does not appear to provide a clinical benefit over MT alone.

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Culture Negative Severe Sepsis: Nationwide Trends and Outcomes

Although 28% to 49% of severe sepsis hospitalizations have been described as being “culture negative,” there are very limited data on the epidemiology and outcomes of those with culture negative severe sepsis (CNSS). The objectives of a study by Gupta et al were to investigate the proportion and trends of CNSS and its association with mortality.

They found that CNSS among hospitalized patients is common, and its proportion is on the rise. They also found that CNSS is associated with greater acute organ dysfunction and mortality.

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Effects of Epinephrine on Cerebral Oxygenation during CPR

Epinephrine has been presumed to improve cerebral oxygen delivery during cardiopulmonary resuscitation (CPR), but animal and registry studies suggest that epinephrine-induced capillary vasoconstriction may decrease cerebral capillary blood flow and worsen neurological outcome. The effect of epinephrine on cerebral oxygenation during CPR has not been documented in the clinical setting. Therefore, Deakin et al examined the effect of epinephrine on cerebral brain oxygenation during in-hospital cardiac arrest.

They found that 1 mg intravenous epinephrine, administered during advanced life support resuscitation, was not associated with a clinically significant change in cerebral tissue oxygenation.

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Airway Driving Pressure and Lung Stress in ARDS Patients

Since the first description of acute respiratory distress syndrome (ARDS) in the 1960s, numerous studies have sought the optimal tidal volume, positive end-expiratory pressure, plateau pressure, and inspired fraction of oxygen to reduce ventilator-induced lung injury. Chiumello et al set out to evaluate if airway driving pressure could accurately predict lung stress in ARDS patients.

They found that airway driving pressure can detect lung overstress with an acceptable accuracy.

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EIP Prolongation in ARDS Patients

End-inspiratory pause (EIP) prolongation decreases dead space-to-tidal volume ratio and partial pressure of carbon dioxide in arterial blood (PaCO2). We do not know the physiological benefits of this approach to improve respiratory system mechanics in acute respiratory distress syndrome (ARDS) patients when mild hypercapnia is of no concern. Aguirre-Bermeo et al, therefore, set out to address this unknown.

They found that prolonging EIP allowed a significant decrease in tidal volume without changes in PaCO2 in passively ventilated ARDS patients. This produced a significant decrease in plateau pressure and driving pressure and significantly increased respiratory system compliance, which suggests less overdistension and less dynamic strain.

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Examining Pantoprazole or Placebo for Stress Ulcer Prophylaxis

Pantoprazole is frequently administered to critically ill patients for prophylaxis against gastrointestinal bleeding. However, comparison to placebo has been inadequately evaluated, and pantoprazole has the potential to cause harm. Therefore, Selvanderan and colleagues set out to evaluate benefit or harm associated with pantoprazole administration.

They found no evidence of benefit or harm with the prophylactic administration of pantoprazole to mechanically ventilated critically ill patients anticipated to receive enteral nutrition.

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Assessing Impact of Conservative vs. Conventional Oxygen Therapy

Among critically ill patients, is a conservative oxygenation strategy aimed to maintain arterial saturation within physiologic limits more beneficial than a conventional strategy? Girardis et al set out to answer this question.

They found that among critically ill intensive care unit patients with a length of stay of 72 hours or longer, a conservative protocol for oxygen therapy may be beneficial; however, because the trial they initiated was terminated early, these findings must be considered preliminary.

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Assessing Tissue Oxygenation and Microvascular Reactivity in ICU Patients

Impaired microcirculatory perfusion and tissue oxygenation during critical illness are associated with adverse outcome. The aim of a study by Donati et al was to detect alterations in tissue oxygenation or microvascular reactivity and their ability to predict outcome in critically ill patients using thenar near-infrared spectroscopy (NIRS) with a vascular occlusion test (VOT).

They found that in critically ill patients, NIRS with a VOT enables identification of alterations in tissue oxygen extraction capacity and microvascular reactivity that can predict mortality.

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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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