UMEM Educational Pearls - By Mike Winters

Dynamic LVOT Obstruction

  • Recent literature has indicated that dynamic LVOT obstruction can occur in critically ill patients without hypertrophic cardiomyopathy. In fact, a recent study found that this condition may be present in many patients with septic shock.
  • Risk factors for  LVOT obstruction include any condition that decreases afterload, decreases preload, or increases heart rate.
  • Consider LVOT obstruction when your ultrasound demonstrates close approximation of the lateral wall and septum plus systolic anterior motion of the anterior mitral leaflet.
  • The treatment of patients with dynamic LVOT obstruction includes:
    • Increasing preload with aggressive IVFs
    • Increasing afterload (phenylephrine may be a good choice)
    • Avoiding inotropes
    • Decreasing heart rate (often with esmolol)

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Category: Critical Care

Title: Oxygen-ICU

Posted: 10/11/2016 by Mike Winters, MD (Updated: 8/17/2022)
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Takeaways

Oxygen-ICU Trial

  • Recent observational trials have demonstrated an association between hyperoxia and worse outcomes in select critically ill patient populations.
  • The Oxygen-ICU Trial was just published online in JAMA, and was an RCT to assess whether a conservative protocol for oxygen supplementation could improve outcomes in critically ill ICU patients compared with usual care.
  • A total of 236 patients were randomized to the conservative oxgyen group (PaO2 target 70-100 mm Hg, SpO2 94-98%), whereas 244 were randomized to the usual care group (PaO2 up to 150 mm Hg, SpO2 97-100%).
  • The results demonstrated that ICU mortality was lower in patients treated witih a conservative oxygen strategy, with an absolute risk reduction of 8.6%.
  • Take Home Point: Be careful with the tiration of oxygen therapy and avoid hyperoxia in many of your critically ill patients.

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Category: Critical Care

Title: Passive Leg Raise

Keywords: passive leg raise, arterial pressure, pulse pressure variation, volume responsiveness, fluid resuscitation (PubMed Search)

Posted: 9/20/2016 by Mike Winters, MD
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Pitfalls with PLR

  • The passive leg raise (PLR) test has become a popular method to assess volume responsiveness in critically ill patients.
  • PLR mobilizes a volume of approximately 150-300 mL and can be used in spontaneously breathing patients, those receiving positive pressure ventilation, or those with various arrhythmias. 
  • In order to properly perform the PLR, you must have a method to monitor cardiac output. (See previously pearl on 7/26/16).
  • Pitfall: Simply monitoring arterial blood pressure alone is not a sufficient method to assess a positive PLR.
  • Pitfalls:Risks of performing a PLR include increased intracranial pressure, reduced cerebral blood flow, and decreased pulmonary compliance.

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Category: Critical Care

Title: Refractory Status Epilepticus

Keywords: refractory status epilepticus, ketamine, propofol, siezure, midazolam (PubMed Search)

Posted: 8/30/2016 by Mike Winters, MD
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Ketamine for RSE?

  • Up to 43% of patients with status epilepticus may progress to refractory status epilepticus (RSE).
  • Propofol, midazolam, and barbituates are often recommended for patients with RSE.
  • Importantly, all of these medications may be limited by hypotension and respiratory depression.
  • Ketamine is emerging as adjuvant therapy for patients with RSE.
  • The loading dose of ketamine ranges from 0.5 to 3 mg/kg, followed by a maintenance infusion of 0.3 to 4 mg/kg/h.

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Category: Critical Care

Title: A Warning to Critical Care Physicians

Keywords: Zika Virus, Guillain-Barre (PubMed Search)

Posted: 8/9/2016 by Mike Winters, MD
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Zika Virus-associated GBS

  • Zika virus has been shown to trigger Guillain-Barre Syndrome (GBS) at a rate similar to Campylobacter jejuni infections.
  • In patients with Zika virus-associated GBS, neurologic deterioration has been rapid, with approximately 33% of patients developing respiratory distress.
  • For patients who have required intubation, the duration of mechanical ventilation and length of ICU stay has been very long.
  • Consider Zika virus-associated GBS in patients with muscle weakness, facial palsy, or paresthesias in the setting of a travel or exposure history to the virus.

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Predicting Fluid Responsiveness with ETCO2

  • It is well known that almost 50% of critically ill patients do not respond to fluid resuscitaiton. For those that do not respond, indiscriminate fluid administration may be harmful.
  • There is increasing emphasis on the use of dynamic markers of fluid responsiveness, namely passive leg raise (PLR), pulse pressure variation, respirophasic changes in the IVC, and many others.
  • ETCO2 can also be used to assess fluid responsiveness in mechanically ventilated patients with no spontaneous respiratory effort.
  • An increase in ETCO2 of at least 5% with a PLR has been shown to outperform arterial pulse pressure as a measure of fluid responsiveness.

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Fentanyl and the Neurologically Injured Patient
  • Emergency providers routinely care for neurologically injured patients, such as those with a SAH or TBI.
  • Many of these patients will require airway management. In these patients, it is important to minimize any increase in ICP, as this can adversely effect cerebral perfusion pressure.
  • When intubating the neurocritical care patient, consider a dose of fentanyl (2 to 5 mcg/kg) prior to intubation. This has been shown to decrease the sympathomimetic response to laryngoscopy.

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LVADs and RV Failure

  • Acute RV failure can be seen in up to 10% of patients after LVAD implantation.
  • The treatment of RV failure in the LVAD patient consists of the following:
    • Fluids: avoid aggressive fluid administration, as this can displace the septum and impair LVAD function
    • Inotropes: consider early initiation of dobutamine, milrinone, or epinephrine to augment RV function
    • Vasopressors: target a MAP higher than 60 to 70 mmHg to maintain RV perfusion pressure
  • If intubated, avoid hypoxia, hypercarbia, high PEEP, and high ventilator pressures.  These can increase pulmonary vascular resistance and further worsen RV function.

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Heat Stroke

  • Heat stroke is critical illness defined as a core body temperature greater than or equal to 40oC and altered level of consciousness.
  • Mortality from heat stroke can be as high as 30%.
  • Numerous methods exist to rapidly cool patients below 39oC.
  • Of these methods, ice-water immersion cools patients the fastest and is highly effective in young patients with exertional heat stroke.
  • There is currently insufficient evidence to routinely recommend antipyretic agents, intravascular cooling devices, body cavity lavage, or the use of ice packs in the groin/axilla/neck. In addition, dantrolene is not recommended in the treatment of heat stroke.

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Situations Where ECMO Will Likely Fail

  • As many EDs and ICUs begin to develop protocols for the use of ECMO, it is important to note select conditions when this therapy is unlikely to be succesful.
    • Chronic respiratory or cardiac disease with no hope of recovery
    • OHCA with prolonged no blood flow
    • Severe aortic regurgitation
    • Type A aortic dissection
    • Refractoroy septic shock with preserved LV function
    • Stem cell transplant patients
    • Advanced age with ARDS
    • Prolonged pre-ECMO mechanical ventilation (> 7 days)
    • Center inexperienced with ECMO

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Can NIV be Used in ARDS?

  • Mechanical ventilation can cause lung injury and increase patient morbidity and mortality.
  • Noninvasive ventilation (NIV) is well-known to decrease intubation rates and improve patient outcome in select disease states (i.e., COPD, acute CHF).
  • For patients with acute respiratory distress syndrome (ARDS), NIV may reduce the work of breathing by opening collapsed alveoli, increasing FRC, and improving oxygenation.
  • To date, there are only a few RCTs that have evaluated the use of NIV in ARDS.
  • Unfortunately, these trials have failed to demonstrate improved patient outcome or decreased intubation rates in patients with ARDS.
  • Clinical Bottom Line: Intubate patients with ARDS who are difficult to oxygenate with standard oxygen therapy.

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Cerebral Venous Thrombosis

  • Approximately 25% of patients with cerebral venous thrombosis (CVT) will experience neurologic deterioration.
  • This is most commonly due to an increase in ICP that results in transtentorial herniation.
  • While heparin remains the treatment of choice for CVT, consider the following alternative strategies in the acutely decompensating patient:
    • Endovascular thrombolysis
    • Mechanical thrombectomy
    • Decompressive hemicraniectomy

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Sepsis-3

  • After nearly 2 decades, the definitions for sepsis and septic shock have been updated.
  • Key findings from the Task Force convened by SCCM and ESICM include:
    • Sepsis
      • Definition: life-threatening organ dysfunction due to a dysregulated host response to infection
      • ICU patients: organ dysfunction is defined as an increase of 2 points or more in the Sequential Organ Failure Assessment (SOFA) score
      • ED patients: 2 or more of the following new qSOFA (quickSOFA) score may identify patients with increased mortality
        • SBP less than or equal to 100 mm Hg
        • RR greater than or equal to 22
        • Altered mental status
    • Septic Shock
      • Definition: a subset of patients with sepsis and profound circulatory, cellular, and metabolic abnormalities
      • Clinical Criteria:
        • Persistent hypotension requiring vasopressors to maintain MAP greater than or equal to 65 mm Hg despite adequate volume resuscitation
        • Lactate greater than or equal to 2 mmol/L
    • The term "severe sepsis" is no longer used

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Shock Index

  • The shock index (SI) is calculated as the ratio of heart rate to systolic blood pressure and is often used in the assessment of critically ill patients.
  • A SI > 0.8 has been shown to be an independent predictor of post-intubation hypotension during emergency airway management.
  • Kristensen and colleagues performed a retrospective review in a single-center in Denmark to evaluate the ability of SI to predict 30-day mortality.
  • In over 110,000 patients, they found a weaker association of SI with 30-day mortality in patients > 65 years of age, those taking a beta-blocker or calcium channel blocker, or those with a history of hypertension.
  • Notwithstanding, a SI > 1 was a significant predictor of mortality across all patient populations and should be considered a warning of serious illness.

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Category: Critical Care

Title: Sickle Cell Disease in the ICU

Posted: 12/29/2015 by Mike Winters, MD (Updated: 8/17/2022)
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Acute Chest Syndrome

  • Acute chest syndrome (ACS) accounts for the most common cause of ICU admission and the most common cause of death in sickle cell patients.
  • Important pearls for ACS include:
    • Chlamydophila pneumonia is the most common bacterial cause of ACS in adults, whereas Mycoplasma pneumonia is the most common bacterial cause in children.
    • CXR abnormalities may be absent early in disease.
    • Children are more likely to have middle lobe disease, in contrast to adults who often have lower lobe involvement.
    • Acute RV failure is a well recognized complication of ACS - use ultrasound to evaluate the RV and be careful with fluids.

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Mechanical Ventilation for Septic Patients in Resource-Limited Settings

  • An international team of physicians just published a series of recommendations for ventilatory support of septic patients in resource-limited settings.
  • Pearls from these recommendations include:
    • Elevate the head of the bed to 30o - 45o
    • Consider tidal volumes of 5 - 7 ml/kg PBW in all patients
    • Use minimum levels of PEEP ( 5 cm H2O) in all patients with sepsis and acute respiratory failure (unless the patient has moderate to severe ARDS)
    • Lower FiO2 to target SpO2 > 88% or PaO2 > 60 mm Hg
    • Use lung ultrasound to evaluate pulmonary edema when CXR is not available
    • Consider using SpO2 to FiO2 (S/F) as an alternative to P/F when blood gas analyzers are not available

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Pain Management in the Critically Ill Patient

  • Pain is common, often underappreciated, and routinely undertreated in our critically ill patients.
  • Poorly treated pain has been shown to adversely affect both short- and long-term outcomes.
  • Key pearls when treating pain in the critically ill:
    • Vital signs should not be used in isolation to assess pain
    • Use a validated assessment tool to objectively quantify pain (i.e., Critical Care Pain Observation Tool)
    • An analgosedation strategy (analgesics before sedative medications) has been shown to decrease duration of mechanical ventilation and decrease ICU LOS
    • Opioids have no maximum or ceiling dose. The appropriate dose is that which controls pain with the fewest side effects.

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Hyperoxia in the Critically Ill

  • Oxygen is liberally administered to many critically ill patients, thereby exposing them to supranormal arterial oxygen levels.
  • Hyperoxia results in the formation of reactive oxygen species, which adversely affect the pulmonary, vascular, cnetral nervous, and immune systems.
  • Though the optimal PaO2 remains unknown, recent evidence indicates that hyperoxia is associated with increased mortality in post-cardiac arrest, CVA, acute coronary syndrome, and traumatic brain injury patients.
  • Take Home Point: Carefully titrate oxygen to the lowest tolerable level to meet the patient's needs.

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Is It Really ARDS?

  • Recent literature suggests that the incidence of ARDS in intubated ED patients may be as high as 10%.
  • The Berlin Definition of ARDS includes the acute onset of bliateral opacities (CXR or chest CT) that is not fully explained by pulmonary edema or fluid overload.
  • Emergency physicians and Intensivists are well versed in lung-protective ventilator settings for patients with ARDS.
  • However, several diseases can appear simliar to ARDS and may require different ventilator strategies and treatments.
  • In the absence of clinical risk factors for ARDS (e.g., sepsis, trauma), consider the following in your differential:
    • Idiopathic pulmonary fibrosis
    • Interstitial pneumonitis
    • Granulomatosis with polyangitis (Wegener's)
    • Diffuse alveolar hemorrhage
    • Goodpasture's syndrome

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Blood Pressure Management in Severe Preeclampsia

  • Severe preeclampsia (preeclampsia + at least one severe complication) accounts for almost 40% of deaths in obstetrical ICU admissions.
  • Systolic arterial hypertension is the most important predictor of morbidity in patients with severe preeclampsia.
  • First-line agents to reduce blood pressure in severe preeclampsia are nicardipine and labetalol.
  • Hydralazine is no longer recommended as first-line therapy.
  • Magnesium is used as an anticonvulsant and should not be considered an antihypertensive.

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