UMEM Educational Pearls - By Mike Winters

Title: HLH in the ED

Category: Critical Care

Posted: 7/20/2021 by Mike Winters, MBA, MD (Updated: 12/12/2024)
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Hemophagocytic Lymphohistiocytosis (HLH)

  • HLH is a hematologic disorder that results from overactivation of the immune response (macrophages and cytotoxic T cells).
  • HLH is often underrecognized and has a mortality that can be as high as 75%.
  • Secondary HLH is most commonly associated with infection (sepsis), malignancy (lymphoma), and autoimmune disorders (SLE, RA).
  • Hallmark features of HLH include fever, splenomegaly, hepatomegaly, cytopenias, coagulopathy, elevated ferritin, elevated triglycerides, and decreased fibrinogen levels.
  • ED resuscitation of patients with suspected HLH includes Hematology consultation, treatment of the underlying disorder (infection), and potentially corticosteroids and chemotherapeutic agents.

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Refractory Anaphylaxis

  • Refractory anaphylaxis is defined as anaphylaxis that does not respond to at least 2 doses of 300 mcg of epinephrine given IM into the anterolateral thigh.
  • Refractory anaphylaxis can be due to several factors including patient comorbidities, delayed diagnosis, delayed epinephrine administration, or concomitant beta-blocker or ACE-inhibitor medication use.
  • Consider the following treatments in patients with refractory anaphylaxis, persistent hypotension, and shock:
    • Aggressive IVF resuscitation - patients may need up to 7L of IVFs
    • Epinephrine infusion (1-10 mcg/min) to target a MAP of 65 mm Hg
    • Glucagon (1-5 mg via slow IV push) for those taking a beta-blocker and who fail to respond to epinephrine
    • Norepinephrine, vasopressin, angiotensin II, methylene blue, or dobutamine can be administered with epinephrine for persistent hypotension. 
    • VA-ECMO - though there is no prospective evidence on the use of ECMO in anaphylaxis.

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Improving Compliance with Lung-Protective Ventilation

  • Approximately 250,000 ED patients are intubated and receive mechanical ventilation each year in the United States.
  • While emergency physicians understand the importance of providing lung-protective ventilation, current studies demonstrate that more than 40% of ED patients are placed on initial tidal volumes > 8 ml/kg of predicted body weight (PBW).
  • In many cases, this may be due to the inaccurate estimation of patient height when determining PBW.
  • In a recent single-center study, Tallman and colleagues evaluated a quality improvement intiative, whereby respiratory therapists were provided with a tape measure and an EHR BPA that reminded them to measure the patient's height for PBW.
  • In this study, these simple, low-cost interventions significantly increased compliance with lung-protective ventilation.
  • Take Home Pearl: Be sure to measure your intubated patient to accurately determine PBW and set the correct tidal volume.

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Mechanical Ventilation in COPD

  • Mechanical ventilation of the patient with obstructive lung disease can be challenging, primarily due to the presence of dynamic hyperinflation.
  • In the initial phase of ventilation, it is important to prevent complications of hyperinflation and not to target normalization of blood gas values.
  • Recommended initial ventilator settings include:
    • Mode: Volume assist-control
    • Inspiratory flow waveform: square
    • Tidal volume: 6-8 ml/kg PBW
    • RR: 12 bpm
    • Inspiratory flow: 60-90 L/min
  • The effect of PEEP is variable with each patient.  When titrating PEEP, be sure to frequently measure plateau pressure and discontinue titration should Pplat increase.

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PEEP in the Intubated Obese Patient

  • Obesity has numerous adverse effects on the respiratory system, most notably a reduction in lung volumes.
  • The reduction in lung volumes (i.e., FRC) often result in airway closure and atelectasis.
  • The application of PEEP in the mechanically ventilated patient helps maintain alveolar patency by preventing derecruitment.
  • Importantly, the typical initial PEEP setting of 5 cm H2O is insufficient for many ventilated obese patients.
  • Pearl: In the ventilated obese patient start with an initial PEEP of 10-15 cm H2O.

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Blood Pressure Management in Acute Ischemic Stroke

  • Blood pressure (BP) is elevated in many patients who present to the ED with an acute ischemic stroke (AIS).
  • Severe elevations in BP are associated with hemorrhagic transformation, as well as cardiac and renal complications.
  • As such, it is important to know the various BP goals for patients with an AIS.
    • Permissive hypertension with a BP less than or equal 220/120 mm Hg is recommended for patients not receiving IV-tPA or endovascular therapy.
    • BP should be lowered to less than or equal to 180/105 mm Hg for patients who have received IV-tPA.
    • BP goals for patients who have received endovascular therapy remain controversial and should be individualized based on the degree of recanalization.

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Ketamine In the Critically Ill Patient

  • Ketamine has become a popular agent in the ED for both RSI and procedural sedation.
  • Given the sedative, analgesic, dissociative, antidepressant, and anti-inflammatory properties, ketamine has also been used in a number of other critical illness conditions including:
    • Acute pain management
    • Status asthmaticus
    • Alcohol withdrawal syndrome
    • Status epilepticus
    • Acute agitated delirium
  • The authors of a recent review in Critical Care Medicine found that the evidence supporting the use of ketamine in the critically ill is most robust for adjunctive analgesia in the intubated patient.  Surprisingly, the data is very limited to support the use of ketamine in these other conditions.
  • Pearl: ketamine does have a myocardial depressant effect, which can be unmasked in states of catecholamine depletion and result in hypotension and bradycadia.

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Analgesics & Sedatives in the Critically Ill Obese Patient

  • Analgesic and sedative medications are frequently administered to critically ill patients.
  • Weight-based dosing regimens for these medications can lead to significant over-, or under-, dosing in the critically ill obese patient (BMI > 40 kg/m2).
  • In order to avoid harm, it is important to know when to use actual body weight (ABW), ideal body weight (IBW), or adjusted body weight in weight-based dosing regimens.
  • Recommendations for weight-based dosing regimens for commonly used analgesic and sedative medications include:
    • Opioids: use IBW or adjusted body weight
    • Ketamine: use IBW or adjusted body weight
    • Propofol: use IBW or adjusted body weight
    • Etomidate: use adjusted body weight or ABW
    • Midazolam: use IBW or adjusted body weight

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Vitamin C for Septic Shock?

  • In 2017, a single center before-and-after study demonstrated benefit for patients with sepsis who received vitamin C, hydrocortisone, and high-dose thiamine.
  • At present, there are more than 30 trials evaluating the use of vitamin C in sepsis.
  • The VITAMINS Trial was recently published and evaluated shock resolution in patients with septic shock who received vitamin C, hydrocortisone, and high-dose thiamine compared to those that received only hydrocortisone.
  • In this randomized controlled trial of 211 ICU patients, the authors found no difference in the primary outcome of time alive and free of vasopressors at 7 days between the two groups.
  • There was also no difference in the secondary outcomes of hospital, 28-day, and 90-day all-cause mortality.
  • Though we still await the results of ongoing trials, the VITAMINS Trial and the recent CITRIS-ALI Trial have not demonstrated benefit of vitamin C for select patient populations with sepsis.

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Mechanical Ventilation Pearls for Acute Ischemic Stroke

  • Patients with an acute ischemic stroke (AIS) may require intubation for various reasons.
  • Two main goals of mechanical ventilation in patients with an AIS are to maintain appropriate oxygen levels and tight control of PaCO2.
  • In terms of oxygenation:
    • Target normoxia
    • Administer O2 if the SpO2 is < 94%
    • Supplemental O2 is not recommended in non-hypoxic patients
  • In terms of CO2:
    • Target normocapnia
    • Hypercapnia increases the risk of intracranial hypertension
    • Hypocapnia can worsen cerebral perfusion

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Interventions Shown to Reduce Mortality in RCTs

  • Santacruz and colleagues recently performed a systematic review to determine which multicenter RCTs in critically ill patients have shown that an intervention was associated with a reduction in mortality.
  • Approximately 13% of the 212 trials included in this review reported a statistically significant reduction in mortality.  Unfortunately, many of the interventions were not associated with reduced mortality in subsequent studies.
  • Interventions consistently shown to reduce mortality in multicenter RCTs in critically ill patients were limited tidal volume in patients with ARDS, noninvasive ventilation in acute hypercapnic respiratory failure, and noninvasive ventilation following extubation in complex cases.
  • Corticosteroids in septic shock, selective digestive decontamination, and prone positioning in ARDS remain controversial.

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The Critically Ill Geriatric Patient with Sepsis

  • Due to the age-related physiologic change of immunosenescence, geriatric patients have an increased susceptibility to infection, a decreased ability to mount a response to infection, and an increased likelihood of atypical presentations.
  • Atypical presentations of sepsis in the geriatric patient include confusion, decreased functional status, generalized weakness, and failure to thrive.
  • In fact, up to 33% of geriatric patients with bacteremia will be afebrile upon presentation.
  • Consider sepsis in the differential diagnosis of geriatric patients with these nonspecific complaints.

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Critical Care Management of AIS

  • In addition to reperfusion therapy, the critical care management of patients with an acute ischemic stroke also includes airway and ventilation management, hemodynamic management, glucose control, anticoagulation management, and surgery in select cases.
  • Consider the following management pearls:
    • Mechanical ventilation
      • Target SpO2 > 94% (avoid supplemental oxygen for non-hypoxemic patients)
      • Target normocarbia (PaCO2 35-45 mmHg)
    • Hemodynamics
      • Target euvolemia with isotonic saline
      • Target BP < 185/110 mmHg for 24 hrs after tPA
      • Target BP < 220/120 mmHg if tPA ineligible
      • Target SBP < 160 mmHg after endovascular therapy
    • Glucose
      • Target serum glucose 140-180 mg/dL

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POCUS in the Critically Ill Pregnant Patient

  • POCUS can be a valuable tool in the assessment and management of critically ill pregnant patients.
  • Conditions to consider in the critically ill pregnant patient who presents with acute RUQ pain include acute fatty liver of pregnancy (AFLP), liver infarction, liver hematoma, and Budd-Chiari Syndrome.
  • POCUS findings for these conditions include:
    • AFLP: a "bright" liver
    • Infarction: a wedge-shaped hypoechoic area (late finding)
    • Hematoma: a heterogeneous fluid collection below the capsule or intraparenchymal
    • Budd-Chiari Syndrome: lack of blood flow or thrombus in a hepatic vein or within the IVC.

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Post-Arrest Prophylactic Antibiotics?

  • Pneumonia is the most common infective complication in post-cardiac arrest patients. It may develop in up to 60% of patients and is associated with an increased ICU length of stay.
  • Given the challenges in diagnosing pneumonia in the post-cardiac arrest patient, many clinicians consider prophylactic antibiotic administration.
  • A recent systematic review and meta-analysis sought to evaluate the effect of early antibiotic use on survival and survival with good neurologic outcome in adult patients resuscitated from cardiac arrest. Key study results include:
    • 11 studies (3 RCTs, 8 observational trials)
    • 6149 patients
    • No change in overall survival or survival with good neurologic outcome
  • Take Home Point: Current data does not support the prophylactic administration of antibiotics to adults resuscitated from cardiac arrest.

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Management of Coagulopathy in Acute Liver Failure

  • Patients with acute liver failure (ALF) frequently require rapid resuscitation to prevent decompensation and multiorgan failure.
  • The most common cause of ALF remains drug-induced injury (i.e., acetaminophen).
  • Though coagulopathy is common in patients with ALF, the prophylactic administration of blood products has not been shown to have clinical benefit.
  • The routine correction of coagulation abnormalities is not currently recommended, unless the patient undergoes a major procedure (e.g., liver transplant).

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Mechanical Ventilation in the Obese Critically Ill

  • Rates of obesity have steadily risen over the past three decades.  In fact, the prevalance of obesity in the ICU is now estimated at 20%.
  • Obesity affects numerous organ systems and impacts the resuscitation and management of these patients.
  • The pulmonary systems undergoes several changes that include decreased lung compliance, decreased chest wall compliance, increased O2 consumption, increased CO2 production, and increased work of breathing.
  • When initiating mechanical ventilation in the obese patient without ARDS, consider the following initial settings:
    • Tidal volume 6 ml/kg ideal body weight
    • PEEP of 10-12 cm H2O
    • RR to achieve a PaCO2 35-45 mmHg
    • FiO2 to maintain SpO2 92-95%
    • Driving pressure < 15 cm H2O

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The Lung Transplant Patient in Your ED

  • Infections are the most common reason for ICU admission in lung transplant patients.
  • Not surprisingly, healthcare-aquired pneumonia is the most common infection seen in lung transplant recipients.
  • In contrast to non-transplant patients, gram-negative bacteria (i.e., Pseudomonas aeruginosa) are the most common pathogens.
  • Be sure to include antimicrobial coverage for Pseudomonas in your lung transplant patients presenting to the ED with pneumonia.

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Hyponatremia in the Brain Injured Patient

  • Hyponatremia is the most common electrolyte disorder in neurocritical care and is associated with increased ICP.
  • The two most common causes of hyponatremia in this patient population are cerebral salt wasting syndrome and SIADH.
  • Symptomatic hyponatremia should be treated with hypertonic saline:
    • 30-45 ml of 10% NaCl or
    • 100-150 ml of 3% NaCl
  • In order to prevent osmotic demyelination syndrome (ODM), sodium should not be corrected by more than 10 mmol/L/day.
  • The risk of ODM is low when acute hyponatremia develops in less than 48 hours.

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A True Tracheostomy Emergency

  • Patients with a tracheostomy often present to the ED for evaluation of a potential complication.
  • Consider a tracheoarterial fistula in any patient with a tracheostomy who presents with brisk bleeding.
  • Most occur within 3 to 4 weeks following tracheostomy placement, and the most common location is the innominate artery.
  • Up to 50% of patients will present with a sentinel bleed - an episode of brisk bleeding that has usually stopped at the time of presentation.
  • For patients who present with active hemorrhage, overinflate the tracheostomy cuff in an attempt to tamponade the bleeding.
  • If that does not stop the bleeding, remove the tracheostomy and compress the artery against the poterior sternum with your finger.

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