Background

• Artificial nutrition is a staple of critical care
• Patients who are unable to eat, require enteral nutrition (preferred over parental nutrition)
• There are some formulas that are called "immunonutrition" which try to alter the inflammatory response seen in critical illness
• They may contain omega-3 fatty acids and essential amino acids such as arginine or glutamine, and anti-oxidants.

Data

• A recent trial (MetaPlus) was designed to see if immunonutrition could decrease the development of infections in the critically ill
• Compared to regular high protein formulas, there was no difference in mortality, duration of ventilation, or hospital length of stay

What to do

• Immuno-nutrition formulas cannot be routinely recommended
• Use regular high protein formulas
• Start within 48 hours of identifying a need

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Sepsis Pearls from the Recent Literature

• Sepsis remains one of the most common critical illnesses managed by emergency physicians and intensivists.
• Recent publications and meta-analyses (i.e., ProCESS, ALBIOS, SEPSISPAM) have further refined the management of these complex patients.
• A few pearls from the recent literature:
  • Early broad-spectrum antibiotics remains the most important factor in reducing morbidity and mortality.
  • Appropriate fluid resuscitation with a balanced crystalloid solution targeting 30 ml/kg. Use a dynamic measure of volume responsiveness to determine if additional fluid needed (i.e., PLR with a minimally invasive or noninvasive cardiac output monitor)
  • Maintain adequate tissue perfusion with IVFs and vasopressors (norepinephrine) targeting a MAP > 65 mm Hg.  Patients with chronic HTN may benefit from a higher MAP goal.  If the diastolic BP is < 40 mm Hg upon presentation, start vasopressors concurrent with IVF resuscitation.

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Should I Give My Patient with Septic Cardiomyopathy Fluids? 

The incidence of acute LV dysfunction in septic shock is estimated to occur in 18 - 46% of patients within the first 24 hours of shock.  Unlike the "classic" pattern of cardiogenic shock where LV filling pressure is high, in septic shock there are normal or low LV filling pressures.

Three therapeutic options should be strongly considered in the patient with a septic cardiomyopathy [CM]:

• FLUIDS:  Most patients with septic CM need fluids to restore adequate preload/afterload.  Severe vasoplegia requires volume resuscitation - even if the bedside ECHO suggests reduced contractility. Give fluids generously.
• Vasopressors: Catecholamine supplementation (norepi) improves patient's preload & afterload, but can often unmask septic CM. Consider epinephrine as a second line agent (over vasopressin) for inotropic support.
• Inotropes: Consider adding epinephrine (1 to 5 mcg/min) or dobutamine (start at 1-5 mcg/kg/min) to target an improved cardiac index (>2.5 L/min/m2) or ScVO2 > 70%.

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There are many ventilator modes to choose from, but almost every mode can be distilled down to its basic principles by understanding the “Three T's of Mechanical Ventilation”

Trigger: You must determine whether the vent or patient will trigger a mechanical breath. For example, machine-triggered breaths (a.k.a. control mode of ventilation) are used for paralyzed patients and will deliver a breath after a period of time has elapsed (e.g., if RR is 10/min, then a breath is given every 6 seconds). On the other hand, if a patient’s respiratory drive is intact (a.k.a. assist-mode) than the patient triggers the breath when the vent detects a patient induced change in airflow or airway pressure. These two modes can also be mixed together.

Target: Mechanical breaths must have a specific target, either a target airway pressure or a tidal volume. Because pressure and volume are directly related, pick the variable you want to target and the other parameter will vary depending on the patient’s intrinsic physiology. For example, if you choose to target a specific tidal volume, we may get one plateau pressure in a patient with normal lungs, but a higher plateau pressure in another patient with stiffer lungs.

Terminate: You must decide when the mechanical breath (i.e., inspiration) terminates and expiration begins. Termination occurs: 1) after a set inspiratory time has elapsed in certain pressure-targeted modes, 2) when a predefined target volume has been achieved (i.e., volume-cycled modes), or 3) when airflow has been reduced by a certain percentage (as in pressure-support ventilation; to be discussed separately)

Let’s put this all together by looking at an example: pressure control ventilation (rate = 12/min and target pressure 20cm H20). Trigger: Because this is a “control”, not assist mode, the machine will trigger a breath 12 times per minute or every 5 seconds. Target: Here we chose to have pressure be the target, so when the ventilator triggers a breath it will deliver a constant airway pressure of 20 cmH2O until we tell the vent terminate that breath. Terminate: the constant airway pressure will be turned off after a fixed period of time has elapsed; for this example we will set the inspiratory time as 1 second, then expiration begins. Now, after a few vent breaths we will observe the results of our settings and reassess; if the resulting tidal volume is lower than what we wanted, we will increase the target pressure to increase the tidal volume. If the tidal volume is higher than what we wanted, we will reduce the target pressure to reduce the tidal volume. We can also tweak the inspiratory time to manipulate the tidal volume, but this does so to a lesser degree.

Try to break down your favorite modes of ventilation using the Three T’s and see if this helps you understand vent modes better. 

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Observation after giving IM Epi for allergic reactions or anaphylaxis

Background

• Common practice is to observe patients who receive epinephrine for allergic reactions or anaphylaxis for several hours post-administration
• This can be from 4-24 hours depending on the institution
• This is to monitor for a biphasic reaction

Question

• Do we need to observe these patients?
• And if so, for how long?

Meta-analysis

• 2 urban Canadian EDs
• 5 year period
• Primary outcome was the amount of patients with a clinically important biphasic reaction
• Secondary outcome was mortality

Results

• 2819 encounters: 496 anaphylactic + 2323 allergic reactions
• 5 clinically important biphasic reactions (0.18%; 95% CI 0% to 0.17%)
• No fatalities
• Biphasic reactions tended to happen several hours (>24hrs) after ED discharge

Limitations

• If patients did not return to an ED in the region, then they would not be identified as a possible biphasic reaction

What to do?

• You can probably discharge most patients whose symptoms have resolved without a prolonged observation period (<4hrs)
• Patients with ongoing anaphylaxis and allergic reaction, should be observed longer or admitted
• Biphasic reactions are very rare

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Predicting Neurologic Outcome in Patients Treated with TTM

• Whether you target 36^oC or 33^oC, targeted temperature management (TTM) improves survival and long-term neurologic oucome in survivors of out-of-hospital cardiac arrest.
• TTM, however, can affect the accuracy and timing of commonly used tests to predict poor neurologic outcome.
• Golan, et al just published a meta-analysis evaluating the accuracy of select diagnostic tests to predict outcome in patients treated with TTM.
  • 20 studies (1,845 patients)
  • Most accurate tests to predict poor neurologic outcome were:
    • Bilaterally absent pupillary reflex (LR 10.45)
    • Bilaterally absent somatosensory-evoked potentials (LR 12.79)
  • Specificity of tests improved when testing was delayed > 72 hours
  • Other commonly used tests (i.e., corneal reflexes, GCS motor score, unfavorable EEG readings) had higher false positive rates and lower LRs

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Patient Positioning During Mechanical Ventilation

In any patient with acute respiratory failure, it is extremely important to consider patient positioning after initiating mechanical ventilation.  Both ventilation (V) and perfusion (Q) of the lungs can be significantly altered by manipulating the way you position your patient.  

• Routine Care: A good rule of thumb is to alays keep the patient's head of bed > 30 degrees whenever possible to maximize diaphragmatic excursion, increase lung expansion, and prevent downstream incidence of ventilator associated pneumonias.
   
• Lateral Decubitus Positioning: Severe unilateral lung disease may warrant alternative patient positiong.
  • Good lung DOWN: In general, the good lung should be placed in the dependent position to improve V/Q matching.
  • Good lung UP: Exceptions where the patient should be placed so the bad lung is in the dependent position include massive hemoptysis (prevent blood from filling the good lung), large pulmonary abscesses (prevent pus from filling the good lung), & unilateral emphysema (prevent hyperinflation)
     
• Reverse Trendelenburg:  In the morbidly obese patient, or those who must remain flat in bed, a trick of the trade to achieve a pseudo-semirecumbent position is to utilize reverse trendelenburg to > 30 degrees.

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• When considering starting a patient on non-invasive ventilation (NIV), ask yourself whether the patient is having a problem of oxygenation (Type I respiratory failure) or a problem of CO2 removal or ventilation (i.e., Type II respiratory failure); don’t forget both types can be present, simultaneously
• Examples of Type I problems are pneumonia and pulmonary edema; examples of Type II problems are COPD, drug overdose, and neuromuscular disease (e.g., myasthenia gravis). Once the underlying problem is identified, selecting the type of NIV is straight-forward. 
• There are only two interventions for type I disorders: 1) increase fio2 and/or 2) increase mean airway pressure (positive end-expiratory pressure; a.k.a. PEEP). There are only two interventions for type II disorders: 1) increase tidal volume and/or 2) increase respiratory rate 
• Continuous positive airway pressure (CPAP) only provides support for type I problems (i.e., can titrate FiO2 and PEEP); CPAP does not provide a tidal volume or a respiratory rate (needed for type II support)
• Bi-level positive airway pressure (BPAP) provides support for type II problems; tidal volume can be titrated by increasing the pressure support and a respiratory rate can be dialed in.

Editors note: The new Back 2 Basic series will review essential critical care concepts on the first Tuesday of each month. Want a specific topic reviewed? Contact us by email or Twitter.

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Risk of infection from Blood transfusions

• We are already moving to decreasing transfusions in general for most of our hospital patients
• But now there is evidence that more transfusions can lead to an increase in nosocomial infections

JAMA Meta-Analysis

• 18 randomized trials with 7,593 patients
• All tested higher vs lower transfusion thresholds in a variety of inpatient settings
• Hospital-acquired infections were the outcome

What they found

• Absolute risk for nosocomial infection was 17% among patients with a higher hemoglobin target compared to 12% with a lower target
• NNT to avoid an infection was 38 using a restrictive transfusion strategy

Bottom Line

• Potential cost savings to the healthcare industry with less transfusions
• For most patients, a hemoglobin > 7 g/dL is just fine

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Prophylactic FFP for Procedures?

• FFP is commonly transfused to correct abnormal coagulation studies prior to performing procedures in nonbleeding critically ill patients.
• Despite common practice, there is little to no supportive evidence to demonstrate a clinical benefit to transfusing FFP in this patient population.
• Muller, et al recently evaluated the use of FFP before invasive procedures in critically ill patients.  Brief highlights include:
  • Prospective, randomized, open-label study at 4 sites in the Netherlands
  • 76 adult ICU patients with INRs between 1.5 and 3.0
  • Procedures: central line placement, thoracentesis, percutaneous tracheostomy
  • Result: no difference in major bleeding events between those who received FFP and those randomized to no FFP
• Take Home Point: In the nonbleeding critically ill patient, routine transfusion of FFP to correct lab abnormalities prior to procedures is not indicated.

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Thrombelastography for Management of Non-Traumatic Hemorrhagic Shock

The use of thrombelastography (TEG, ROTEM) has traditionally been utilized and studied in the management of acute coagulopathy of trauma (ACoT) developed by patients in hemorrhagic shock secondary to trauma.

Functional coagulation tests such as the TEG may provide valuable information when resuscitating the hemorrhaging patient, especially if there is any concern for an underlying coagulopathy.  

The following is a TEG recently returned during the resuscitation of a 60 y/o male with a history of HCV cirrhosis presenting with hemorrhagic shock secondary to a massive upper GIB.  The University's Massive Transfusion Protocol was promptly activated and at this point, the patient had received approximately 4 units of PRBCs & FFP along with 1 liter of crystalloid.  His Hgb was 5, PT/PTT/INR were undetectable, and his fibrinogen was 80.

Below is a table that simplifies the treatment, based on the test's abnormalities:

• Prolonged R:  Fresh frozen plasma
• Prolonged K or reduced α angle: Cryoprecipitate
• Low MA: Platelets, desmopressin (DDAVP)
• Elevated LY 30%: Consider antifibrinolytics (aminocaproic acid, TXA)

After reviewing the initial TEG, all perameters were abnormal in addition to the presence of significant fibrinolysis.  The patient was given an additional 4 units of FFP, DDAVP, cryoprecipitate, a unit of platelets, and aminocaproic acid.  The patient still required significant resuscitation, however bleeding had significantly decreased as well has his pressor requirement.  Below is the patient's follow-up TEG 2 hours later.

There is growing enthusiasm for the use of functional coagulopathy testing in the patient with hemorrhagic shock.  Early resuscitation with blood products as your fluid of choice with limited fluid administration while arranging for definitive source control are critical, but also consider early thrombelastography to detect additional causes for uncontrolled hemorrhage.

References

1. Walsh M, Thomas SG, Howard JC, et al. Blood component therapy in trauma guided with the utilization of the perfusionist and thromboelastography. Journal of Extra-Corporeal Technology. 2011 Sep; 43(3):162-7.
2. The Use of TEG & Goal Directed Blood Component Therapy.  MarylandCCProject.org

Follow Me On Twitter: @JohnGreenwoodMD
email: johncgreenwood@gmail.com

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Emergent reversal of Dabigatran

What is it:

Direct thrombin inhibitor used for stroke prevention in non-valvular atrial fibrillation

When do I worry about reversal:

Patients can have clinically important bleeding (GI hemorrhage, or Intracranial bleeding) or need reversal for emergent surgery

Patients with renal failure can have a prolonged medication effect

What can I do:

1.     Activated charcoal: good for recent overdose or recent ingestion (within 2 hours)

2.     Hemodialysis:  around 60-65% can be removed within 2-4 hrs; putting in a dialysis line can be…bloody

3.     FFP: in rat studies, has been shown to reduce the volume of intracranial hemorrhage. Unknown in humans. No good evidence of use based on coagulation mechanisms. Still worth a try though. 

4.     Recombinant activated factor VII: Has been shown to correct the bleeding time in animal studies. Probably the best bet in severe bleeding

5.     Pro-thrombin complex concentrate: has been shown to decrease the bleeding time in animal studies

How do I monitor effect?

No great way here. Check aPTT and thrombin time (TT). At supra-therapeutic doses there is no good test. 

Coming attractions: Dabigatran-fab for emergent reversal (see previous pearl: https://umem.org/educational_pearls/2415/) 

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Are Intermediate Lactate Levels Concerning in Patients with Suspected Infection?

• It is well known that lactate levels > 4 mmol/L are associated with increased mortality in patients with suspected infection.
• What is unclear, however, is the prognostic value of intermediate lactate levels (2.0-3.9 mmol/L) in patients with suspected infection.
• Puskarich, et al. performed a systematic review to determine the risk associated with intermediate lactate levels.
  • 8 studies (> 11,000 patients) were included in the analysis
  • Mortality for patients with intermediate lactate levels but without hypotension was 15%
  • Mortality was > 30% for hypotensive patients with intermediate levels of lactate.
• Take Home Point: Patients with intermediate lactate levels have an increased risk of mortality.
• Though no current guidelines exist for the optimal care of these patients, aggressive care should continue until repeat levels demonstrate normalization.

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Carbapenem Resistant Organisms are HERE

We've all heard Dr. Bryan Hayes warn us that, "Vanc & Zosyn is NOT the Answer for Everything" but things just got a little more serious, on a whole 'nother level...

Within the past few months, 2 cases of NDM-producing carbapenem-resistant pseudomonas have been reported in the area - one in Delaware and one in Pennsylvania.  Previously, the only reported cases were found in Europe.  

It's important for EM physicians to be aware of carbapenem resistant organisms and infections because:

• They have been independently associated with an increase in mortality
•  Are increasing in frequency around the world
• Are a major threat to our antimicrobial armamentarium

Risk factors for carbapenem resistance 

• Stem cell transplant patients
• History of mechanical ventilation
• Recent ICU stay
• Previous exposure to antibiotics

Antimicrobial options

Few treatment options are currently available for carbapenem resistant organisms.  

• Polymixins (colistimethate & polymyxin B)
• Tigecycline
• Fosfomycin
• Some aminoglycosides (amikacin, gentamicin, & tobramycin)

Appear to have retained some in vitro activity against these organisms, but are generally used as, "drugs of last resort". 

What should you do about it?

Know it exists, take a good history, & know your local antibiogram.  Prior to selecting a broad spectrum antimicrobial regimen, try to obtain previous antimicrobial culture data for patients with resistant organism infectious risk factors.

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Prior literature has demonstrated the safety and feasibility of placing subclavian lines with ultrasound guidance; here's a link to a short educational video describing the technique. 

The literature has been varied, however, as to which approach is best for venous cannulation with ultrasound; the supraclavicular (SC) or infraclavicular (IC) approach (see references below)

A recent study evaluated both approaches in healthy volunteers in order to determine which approach is superior for cannulation using ultrasound.

98 patients were prospective evaluated by Emergency Medicine physicians with training in ultrasound. In each patient, both SC and IC views were evaluated on both the left and right sides; each view was given a grade for ease of favorability (no patients were actually cannulated)

Overall, it was found that the SC view was significantly more favorable compared to the IC view; the right SC was non-significantly preferred compared to the left SC.

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High Flow Nasal Cannula

What is it?

• High flow nasal cannula has been used in pediatrics for some time now
• It can be used in adults as well
• It is a simple nasal cannula setup with larger cannula sizes in both nares
• It is heated, humidified oxygen
• You can control your oxygen level and flow of oxygen

Benefits

• Small amount of PEEP provided to the patient (estimated 5-7 cm H20)
• Improves oxygenation (more reliable oxygenation than a non-rebreather face mask)
• Can provide some alveolar recruitment
• Increases FRC (functional residual capacity)
• Pharyngeal dead space washout

Who to use it on

• Acute hypoxemic respiratory failure
• Pre-intubation (can place before and during intubation in patients who have low oxygen saturation)
• Post-extubation
• Palliative care (DNI patients)

How to set it

• Flow rates: 0-60 L/min
• Spontaneously breathing patient with mild-moderate hypoxemia/respiratory distress:

            -15-30 L per minute

            -100% oxygen (wean as tolerated)

            -temp 35-40 C

            -when weaning decrease oxygen prior to flow

Bottom line: No evidence that it reduces intubation rates in patients with hypoxemic respiratory failure but may improve oxygenation issues while deciding on treatment options

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Antibiotic Timing in Severe Sepsis/Septic Shock

• Though the recent ProCESS trial has questioned the utility of central hemodynamic monitoring and protocol-based resuscitation, early antibiotic administration remains paramount in the care of patients with severe sepsis/septic shock.
• Retrospective studies have demonstrated that delays in antibiotic administration are associated with marked increases in hospital mortality.
• Notwithstanding, delays in antibiotic administration remain all too common.
• Ferrer et al, have just published the largest cohort to date analyzing the association of antibiotic timing to hospital mortality in patients with severe sepsis or septic shock.  The key findings include:
  • Retrospective cohort of 17,990 patients from the SSC database.
  • Hospital mortality rose linearly for each hour delay in antibiotic administration.
  • Odds ratio for hospital mortality increased from 1 to 1.52, as the delay increased from 0 to 6 hours after presentation.
• Key Point: Antibiotic timing matters!

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Direct vs. video laryngoscopy in the patient with an acute TBI

Hypoxia and hypotension are considered the "lethal duo" in patients with traumatic brain injury.  In a recent randomized control trial (by our own Dr. Dale Yeatts at the Shock Trauma Center) mortality outcomes were compared between 623 consecutive patients who were intubated with either direct laryngoscopy (DL) or video laryngoscopy (VL).  Here is what they found:

1. No significant difference in mortality for all comers (Primary Outcome)
2. In the subset of patients with severe head injuries, there was:

• A significantly higher mortality in patients with TBI if VL was used
• A significantly longer intubation duration for VL (74 sec) than DL (65 sec)
• A greater incidence of low oxygen saturations of 80% or less in the VL group (27 patients) than DL (15 patients) - objectively recorded data, not self reported.

There is a reasonable amount of literature that shows hypoxia and hypotension significantly contribute to morbidity & mortality in the TBI patient, and a growing body of literature that suggests intubation with VL takes longer than DL.

Bottom Line: When choosing a method of intubation for the TBI patient, remember the "Lethal Duo" and consider direct laryngoscopy with manual inline stabilization first.

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• Only 50% of hemodynamically unstable patients will improve their hemodynamics in response to a fluid bolus. However, because excessive fluid administration can lead to organ edema and dysfunction, it is important to give hemodynamically unstable patients only the necessary amount of fluids to improve their hemodynamics.

• There are two general categories of assessing a patient's response to volume administration; static and dynamic assessments (see referenced article below):

  • Static assessment (generally unreliable, but traditionally used):

    • Physical exam (dry mucus membranes, cool extremities, etc.)

    • Urine output

    • Blood pressure

    • Central venous pressure via central-line

  • Dynamic assessment (more reliable but more labor intensive)

    • Pulse Pressure Variation

    • IVC Distensibility Index

    • End-expiratory occlusion test

    • Passive Leg-Raise

• There is no simple way to accurately determine the need for a fluid bolus however the integration of the techniques above can help the clinician make better decisions.

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