UMEM Educational Pearls - Critical Care

Lung Protective Ventilator Settings Still Underutilized

  • It's been over 10 years since the publication of the ARDSnet trial, which demonstrated an 8.8% absolute reduction in short-term mortality for patients with ARDS ventilated with "lung protective" settings (tidal volume 6 ml/kg, plateau pressure < 30 cm H20).
  • A recent study in the BMJ evaluated the association of these settings with 2-yr survival in patients with acute lung injury.
  • The study, carried out in 13 ICUs from 4 academic hospitals in Baltimore, found some surprising results:
    • In patients whose ventilator settings were 100% compliant with lung protective settings, there was an 8% absolute reduction in mortality.
    • For each increase of 1 ml/kg above recommended tidal volume there was an 18% relative increase in mortality.
    • 37% of patients never received lung protective ventilation.
  • Take home point: lung protective settings appear to confer not only short-term but also long-term mortality benefit for patients with acute lung injury, yet remain underutilized even in major academic centers.

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Crystalloids (i.e., 0.9% saline and lactated ringers) have been used during resuscitation for more than a century. Their invention, however, was more accidental than intentional.

Crystalloids were first used during the European Cholera epidemic of 1831. Hartog Hamburger later modified this solution in 1896 to the solution we know today as "normal" saline. Hamburger's solution was only intended for in vitro study of RBC lysis and was never intended for clinical use.  

Around this time, Sydney Ringer was testing several fluids to use for physiologic studies. Ringer's lab assistant was erroneously substituting tap water for distilled water when preparing these solutions. Ringer later discovered that this tap water contained minerals making the solution "physiologic", isotonic, and safe for human use; Alexis Hartmann later added sodium lactate to create Ringer's Lactate. 

Since the invention of crystalloids, many types of resuscitation fluids have been created and studied (i.e., albumins, gelatins, and starches); all have been shown to be more expensive, with no more benefit, and with possibly more harm when compared to crystalloids. 

The "perfect" resuscitation fluid still alludes us today, but of all of the solutions marketed crystalloids are arguably the best...despite their accidental history.

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Category: Critical Care

Title: Steroids and Septic Shock

Posted: 7/24/2012 by Mike Winters, MD (Updated: 4/22/2024)
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Steroids and Septic Shock

  • Do low-dose steroids improve mortality or shock reversal in patients with septic shock?
  • A recent systematic review published in the Journal of Emergency Medicine found:
    • A statistically significant improvement in shock reversal (RR 1.17)
    • A favorable, but not statistically significant, mortality benefit for patients with refractory septic shock (RR 0.92; CI 0.79-1.07)
  • Most guidelines recommend against steroids for septic patients that are responding to fluid resuscitation and vasopressor therapy.
  • Updated guidelines from the Surviving Sepsis Campaign (soon to be published) will continue to recommend low-dose IV corticosteroids (200 mg over 24hrs) for those who are refractory to fluids/vasopressors.

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Wernicke encephalopathy (WE) is a neurologic disorder secondary to prolonged thiamine deficiency; it is characterized by confusion, ataxia, and ocular abnormalities. 

Traditional medical teaching advises against the administration of glucose (or glucose containing fluid) in thiamine deficient patients, without first giving thiamine, as this may precipitate WE. 

This teaching is problematic, however, in hypoglycemic patients who require the immediate administration of glucose while simultaneously being suspected of thiamine deficiency (e.g., malnourished alcoholics). Delays in treating hypoglycemia may be more harmful (e.g., seizures, permanent neurologic deficits, etc.) than the risk of WE.

Schabelman et. al performed a literature search to unearth the origins of this teaching. Nineteen papers related to this topic were found consisting of case reports, animal studies, and expert opinion; there were no randomized trials, cohort studies, or case-control studies.

Bottom-line: The available evidence does not support withholding glucose treatment until thiamine can be administered and educators should consider abolishing this dogmatic teaching until better evidence is available.

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Category: Critical Care

Title: Anaphylaxis

Posted: 7/10/2012 by Mike Winters, MD (Updated: 4/22/2024)
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Anaphylaxis

  • The incidence of anaphylaxis appears to be rising.
  • Recall that death can occur anywhere from 5 to 30 minutes after allergen exposure.
  • A few important pearls in management:
    • Epinephrine is the drug of choice and should be given intramuscularly (not subcutaneous) in the mid-anterolateral thigh.
    • Be aggressive with IV fluids, as up to 35% of circulating volume can be extravasated within 10-15 minutes of symptom onset.
    • Get an ECG ASAP! Mast cells are located around the coronary arteries.  The release of mediators can induce vasospasm and precipitate an acute coronary syndrome.

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Category: Critical Care

Title: Decisions, Decisions...Crystalloid or Colloid?

Keywords: hydroxyethyl starch crystalloid, colloid, lactated ringers, normal saline, resuscitation, sepsis, hypotension (PubMed Search)

Posted: 7/3/2012 by Haney Mallemat, MD
Click here to contact Haney Mallemat, MD

Septic patients with hemodynamic instability often require intravenous fluids as part of their resuscitation. Major debate has occurred whether the optimal resuscitation fluids are crystalloids (e.g., normal saline) or colloids (e.g., albumin).

In theory, colloids are more potent intravascular expanders than crystalloids because their oncotic pressure is higher and should increase intravascular volume similarly to larger amounts crystalloid (i.e., colloids require less volume during resuscitation). 

Despite these theoretical benefits, the colloid hydroxyethyl starch (HES), has come under scrutiny after prior studies have linked its use with adverse outcomes. 

A recent prospective randomized-control trial compared the use of HES to lactated acetate for resuscitating septic patients and found that HES significantly increased both the incidence of renal-replacement therapy and mortality at 90 days (both primary end-points in the study).

Bottom line: There is no convincing data that HES performs superiorly to crystalloid for resuscitation in sepsis and there is increased harm with its use. Furthermore, the increased cost of HES compared to crystalloids does not justify its routine use.

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Acute Kidney Injury and Tumor Lysis Syndrome

  • Tumor lysis syndrome (TLS) is characterized by hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia.
  • Acute kidney injury in TLS increases patient mortality and can be caused by an obstructive uropathy from calcium phosphate crystalluria or uric acid crystal precipitation.
  • Fluid resuscitation remains the primary treatment for TLS.
  • Urine alkalinization, however, is no longer recommended, as it can result in calcium phosphate crystal precipitation. 
  • Recombinant urate oxidase rapidly decreases uric acid levels and should be given to patients at high-risk for TLS and those with pre-existing kidney disease and high uric acid levels.

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Two recently presented abstracts at the 2012 Society of Critical Care Medicine conference suggest that the combination of vancomycin and piperacillin-tazobactam may lead to acute kidney injury (AKI) in the critically ill. There may also be evidence to suggest that piperacillin-tazobactam alone increases the risk of AKI.

Both abstracts retrospectively compared patients who received either vancomycin alone or the combination of vancomycin and piperacillin-tazobactam. In both studies, the rates of AKI were significantly lower in patients treated with vancomycin alone as compared to patients receiving both vancomycin and piperacillin-tazobactam.

Bottom line: Although the current evidence does not support a change in our clinical practice, more prospective studies exploring this topic are necessary.

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Category: Critical Care

Title: Anion Gap in DKA

Posted: 6/13/2012 by Mike Winters, MD (Updated: 4/22/2024)
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Use the Measured Sodium Concentration!

  • During a recent shift, a question arose regarding whether to use the measured or corrected sodium to calculate the anion gap in a critically ill patient with DKA.
  • Recall that the anion gap provides an estimation of unmeasured anions - in this case acetoacetate and beta-hydroxybutyrate.
  • Glucose is electrically neutral and therefore does not affect the anion gap.
  • When calculating the anion gap in a patient with DKA, use the actual (measured) serum Na, rather than the corrected value.

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Category: Critical Care

Title: Rhabdomyolysis and Heat Exposure

Posted: 6/4/2012 by Haney Mallemat, MD (Emailed: 6/5/2012) (Updated: 6/5/2012)
Click here to contact Haney Mallemat, MD

Consider rhabdomyolyisis secondary to heat exposure as summertime approaches; have a low threshold to screen patients if they are at risk (e.g., people exercising in high-ambient temperatures).

Symptoms include muscle tenderness, cramping, and swelling with associated weakness. Patients with altered mental status (e.g., heat stroke) should be examined for limb induration, skin discoloration (i.e., ischemia), or compartment syndrome.

Complications:

  • Electrolyte abnormalities (e.g., hyperkalemia and hypocalcemia) and malignant cardiac arrhythmias
  • Metabolic acidosis
  • Disseminated intravascular coagulation (release of tissue factor from muscle cells)
  • Acute renal failure (myoglobin directly causes nephrotoxicity)

Treatment

  • External cooling to cease the inciting process
  • Aggressive fluid resuscitation with normal saline (avoid lactated ringers) for goal urine output of 200 to 300 ml/hour; foley catheters should be placed to monitor urine output.
  • Start dialysis if potassium levels are elevated, acidosis, or oliguric renal failure. There is very limited evidence for the use of dialysis before the presence of these signs.
  • There are no randomized controlled trials to support the use of mannitol (free radial scavenger and diuretic) or bicarbonate (to alkalinize the urine); their use is controversial.

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Category: Critical Care

Title: Severe UGIB

Posted: 5/29/2012 by Mike Winters, MD (Updated: 4/22/2024)
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Severe UGIB

  • Differentiating between upper and lower GIB can be challenging. 
  • A recent review evaluated the accuracy of historical features, symptoms, signs, and lab values in distinguishing between UGIB and LGIB. 
  • Features with the highest likelihood for identifying UGIB included:
    • Melenic stool on exam (LR 25)
    • A prior history of UGIB (LR 6.2)
    • Serum urea:creatinine ratio > 30 (LR 7.5)
  • Features that increased the likelihood of severe UGIB (defined as requiring blood transfusion, need for urgent endoscopy, surgery, or interventional radiology) included:
    • Heart rate > 100 bpm (LR 4.9)
    • Hemoglobin < 8 g/dL (LR 6.2)
    • History of cirrhosis or cancer (LR 3.7)
  • For patients with an UGIB, the Blatchford Score can be used to determine the need for urgent intervention.  Those with a Blatchford Score of 0 have a low likelihood for severe UGIB and may not need emergent intervention.

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Category: Critical Care

Title: Carcinoid-induced Heart Failure

Posted: 5/21/2012 by Haney Mallemat, MD (Emailed: 5/22/2012) (Updated: 5/22/2012)
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Carcinoid tumors are neuroendocrine malignancies typically located in the GI tract; most commonly in the terminal ilium and appendix.

Carcinoid tumors produce serotonin, histamine, bradykinin, and/or prostaglandin that result in diarrhea, facial flushing, or bronchospasm. These vasoactive substances may also lead to hypotension and vasodilatory shock.

The tumor may also affect the tricuspid and pulmonary valves leading to right-heart failure secondary to valvular regurgitation, stenosis or both.

Treatment is directed at controlling the malignancy (e.g., octotrotide and tumor resection) as well as managing the right-sided heart failure when it occurs (e.g., inotropes, diuretics, vasopressors, etc.).

 

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Balloon Tamponade for Variceal Bleeding

  • Despite advances in pharmacology and endoscopy, placement of a balloon tamponade device is occasionally required to stabilize a patient with acute variceal bleeding.
  • Currently, there are 3 devices available: the Linton-Nachlas (gastric balloon only), the Blakemore (gastric and esophageal balloons), and the Minnesota (gastric and esophageal balloons) tubes.
  • The tube should initially be passed at least to the 50-cm mark and preferably to the maximum depth allowed by the length of the tube.
  • Once the gastric balloon is inflated and correct position confirmed, traction must be applied to keep the gastric balloon engaged in the cardia and fundus of the stomach.
  • An overhead pulley system is the preferred method to deliver traction.  If you don't have weights for the pulley system, a 1-liter bag of crystalloid provides the desired 1.0 kg of traction.


Severe acute pancreatitis (SAP) is a life-threatening form of pancreatitis, with up to 30% mortality.

SAP may lead to hypovolemic shock (secondary to vasodilation and capillary leak), hypoxemia (from acute respiratory distress syndrome), and multi-organ failure.

Suspect SAP with signs and symptoms of pancreatitis plus any of the following:

  • Hypotension
  • Hypoxemia
  • Elevated hematocrit (secondary to hemoconcentration)
  • Metabolic acidosis
  • Decreased ionized calcium

Treatment of SAP should focus on:

  • Hemodynamic support including intravascular volume repletion
  • Respiratory support to correct hypoxemia
  • Screening for abdominal compartment syndrome (risk increased with SAP)
  • Prophylactic antibiotics are not recommended

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Category: Critical Care

Title: SBP, HRS, and Albumin

Keywords: spontaenous bacterial peritonitis, hepatorenal syndrome, albumin (PubMed Search)

Posted: 5/1/2012 by Mike Winters, MD (Updated: 4/22/2024)
Click here to contact Mike Winters, MD

SBP, HRS, and Albumin

  • Spontaneous bacterial peritonitis (SBP) is the most common infection in patients with end-stage liver disease (ESLD).
  • In critically ill patients, SBP can precipitate type 1 hepatorenal syndrome (HRS), which, if not treated, carries a mortality > 90%.
  • Infusion of albumin at 1.5 g/kg at the time of SBP diagnosis (and a second dose of 1 g/kg on day 3) has been shown to significantly decrease the incidence of type 1 HRS and decrease mortality.
  • In your next critically ill patient wth ESLD, strongly consider giving albumin at the time of SBP diagnosis.

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Mediastinitis is an infection of the mediastinum; a rapidly fatal surgical emergency if not recognized and treated early.

Causes include esophageal perforation, oropharyngeal infections (e.g., Ludwig’s angina), prevertebral or carotid space infections, and iatrogenically (endoscopy, hypopharyngeal perforations during intubation, etc.).

Plain films (neck / chest) may serve as a screening tool, but CT best defines the source and extent of disease; the CT below demonstrates gas within the soft-tissues and the mediastinum (red arrrows).

Infections may be polymicrobial and broad-spectrum antibiotics with anaerobic coverage (e.g., pipercillin-tazobacam) should be started initially.

Immediate treatment should also include:

  • Intubation (with co-existing soft tissue swelling)
  • Fluid resuscitation and hemodynamic support
  • Surgical consult for necrotic tissue debridement

 

Bonus Pearl

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Cuff Pressures and the Prevention of VAP

  • As highlighted in a recent pearl, ventilator-associated pneumonia (VAP) is the second most common nosocomial infection in the US and is associated with increases in ICU length of stay and mortality.
  • With increasing ED lengths of stay for many critically ill patients receiving mechanical ventilation, measures to prevent VAP should be initiated in the ED.
  • In addition to elevating the head of the bed to 30-45 degrees, another low cost intervention is the measurement of endotracheal tube cuff pressures.
  • Cuff pressures below 20 cm H2O increase the risk of VAP.
  • Measure cuff pressure within 4 hours of inflation and maintain between 20-30 cm H2O.

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Category: Critical Care

Title: Reducing nosocomial sepsis

Posted: 4/9/2012 by Haney Mallemat, MD (Emailed: 4/10/2012) (Updated: 8/12/2014)
Click here to contact Haney Mallemat, MD

Sepsis is one of the top 10 causes of death in the U.S. and its incidence is on the rise.

The financial burden of sepsis is also growing; it is estimated that between 2000 and 2005 the overall cost of ICU hospitalization rose from $56.6 billion to $81.7 billion per year with severe sepsis accounting for $16.7 billion.

Although we may not be able to immediately modify the incidence of community-acquired sepsis, hospital-acquired sepsis can be reduced; for example, many cases of nosocomial sepsis are associated with catheter blood stream infections secondary to central-lines.

There are several simple strategies to prevent catheter-related blood-stream infections:

  • Ensure proper hand hygiene prior to central-line insertion
  • Use maximum sterile procedures during insertion of central venous catheters
  • Use skin antiseptics and proper dressings at catheter insertion sites
  • Rapid discontinuation of central venous catheters once no longer needed

Remember: We play a large role in reducing nosocomial sepsis; be vigilant about your sterile techniques during central catheter insertions and question the need for every single line.

 

Bonus pearl (only for iPhone): MDRNTools is a FREE app (that’s right, FREE!) with lots of ED and ICU applications such as an IV med calculator, an RSI handbook, a Stroke Scale calculator, and more.

Download http://itunes.apple.com/us/app/mdrntools/id505794224?mt=8&ls=1

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Transferring Multidrug-Resistant Organisms

  • Hospital-associated infections are a major cause of morbidity and mortality, especially among the critically ill.
  • Worldwide, the emergence of multidrug-resistant (MDR) bacteria has caused significant problems.
  • A recent study from the University of Maryland examined the impact of environmental contamination on the rate of transfer of MDR bacteria to healthcare workers clothing.
  • Two important findings from this study of ICU patients were:
    • Up to 8% of healthcare workers entered a patient's room with MDR bacteria on their hands
    • Almost 5% of healthcare workers had MDR bacteria (most notably Acinetobacter) on their hands upon exiting the room despite using gloves and a gown
  • Take Home Point: Be sure to use hand hygiene upon entering and exiting a patient's room who is colonized with MDR bacteria!

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Category: Critical Care

Title: Want more apnea time during Rapid Sequence Intubation? Raise the head of the bed.

Keywords: apnea time, rapid sequence intubation, atelectasis, crticial care, intubation, hypoexemia, obesity (PubMed Search)

Posted: 3/26/2012 by Haney Mallemat, MD (Emailed: 3/27/2012) (Updated: 3/27/2012)
Click here to contact Haney Mallemat, MD

The supine position during rapid sequence intubation may result in posterior lung atelectasis thereby reducing lung volumes, oxygenation reserve, and ultimately apnea time.

Several studies have shown that elevating the head of the bed by at least 20 degrees or placing a patient in reverse Trendelenberg position (for patients with contra-indications to elevating the head of the bed) during RSI may significantly increase apnea time.

Elevating the head of the bed may be especially helpful for patients with BMIs >35

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