UMEM Educational Pearls - Critical Care

Mechanically ventilated patients can develop a condition in which air becomes trapped within the alveoli at end-expiration; this is called auto-PEEP.

Auto-peep has several adverse effects:

  • Barotrauma from positive pressure trapped within the alveoli 
  • Increased work of breathing
  • Worsening pulmonary gas exchange
  • Hemodynamic compromise secondary to increased intra-thoraic pressure

Auto-PEEP classically occurs in intubated patients with asthma or emphysema, but it may also occur in the absence of such disease. The risk of auto-PEEP is increased in patients with:

  • Short expiration times (i.e., inadequate time for the evacuation of alveolar air at end-expiration)
  • Bronchoconstriction
  • Plugging of the bronchi (e.g., mucus or foreign body) creating a one-way valve and air-trapping

Auto-PEEP may be treated by:

  • Reducing tidal volume
  • Reducing the respiratory rate
  • Decreasing inspiratory time
  • Increasing PEEP

Patients may need to be heavily sedated to accomplish the above ventilator maneuvers.

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Ventilator-associated Pneumonia

  • Ventilator-associated pneumonia (VAP) is a well known complication of mechanical ventilation (MV) and is associated with increased duration of MV, hospital length of stay, and cost.
  • VAP is commonly associated with multi-drug resistant organisms, including Pseudomonas, Acinetobacter, Klebsiella, and Enterobacteriaceae.
  • Given the significant impact upon morbidity, a number of organizations have recommended "bundles" of care for the prevention of VAP.
  • Important measures for the prevention of VAP include:
    • Strict hand hygiene
    • Head of bed elevation to 30-45 degrees
    • Closed endotracheal suctioning
    • Maintaining endotracheal tube cuff pressure > 20 cm H2O
    • Oral chlorhexidine rinses
    • Orogastric tube placement

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Excessive and improper administration of local anesthetic (a.k.a. local anesthetic systemic toxicity or L.A.S.T.) can lead to cardiac toxicity with symptoms ranging from benign arrhythmias to overt cardiac arrest. 

Administration of a 20% intra-lipid emulsion has been experimentally known to reverse L.A.S.T in animal models, but in 2006 the first documented human case of ILE was successfully used during cardiac arrest secondary to L.A.S.T. with hemodynamic recovery and good neurologic outcome. Many case reports have emerged since then, including the use of ILE in toxicity with other lipophilic drugs (e.g., calcium channel blockers, tricyclic antidepressants, etc.)

Several mechanisms have been proposed explaining how ILE works. They include:

  • binding circulating toxins in the blood stream, minimizing its exposure to tissues
  • improving mitochondrial metabolism (which is inhibited in L.A.S.T.) 
  • reducing re-perfusion injury and cellular apoptosis post cardiac-arrest

Dosing of ILE:

  • 1.5 mL/kg intravenous bolus of 20% ILE over 2-3 minutes (may be repeated, if necessary) then,
  • starting a continuous infusion of 0.25-0.5 mL/kg/min and continuing infusion for 10 minutes after vital signs return.

Check out this video by our own Dr. Bryan Hayes(@PharmERToxGuy) and Lipidrescue.org for more information.

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Managing Traumatic Hemorrhagic Shock

  • When managing the critically ill patient with traumatic hemorrhagic shock, the primary objectives are to stop bleeding, maintain tissue perfusion and oxygen delivery, and limit organ dysfunction.
  • Pearls to consider when resuscitating these patients include:
    • In the patient without brain injury, target an SBP of 80 - 100 mm Hg until major bleeding has been controlled.
    • Limit aggressive fluid resuscitation
    • Avoid delays in blood and blood component transfusion.  Transfuse early. Though the optimal ratio remains controversial, most transfuse PRBCs and FFP in a 1:1 ratio.
    • Consider point-of-care testing, such as thromboelastography (TEG), to assess the degree of coagulopathy and guide transfusion strategies.
    • Consider the use of tranexamic acid

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Propofol is generally a well-tolerated sedative / amnestic but occasionally it can lead to the propofol infusion syndrome (PRIS); a metabolic disorder causing end-organ dysfunction.

Suspect PRIS in patients with increasing lactate levels, worsening metabolic acidosis, worsening renal function, increased triglyceride levels, or creatinine kinase levels. End-organ effects include:

  • Myocardial dysfunction / Arrhythmias
  • Rhabdomyolysis
  • Acute renal failure

The true incidence of PRIS is unknown, however, certain risk factors have been identified:

  • Doses >4-5mg/kg/hour
  • <18 years of age
  • Critically-ill patients; especially receiving vasopressors or steroids
  • History of mitochondrial disorders
  • Infusions >48 hours

Prevent PRIS by using adequate analgesia (with morphine or fentanyl) post-intubation, which may reduce the overall dosage of propofol ultimately reducing the risk.

If PRIS develops, stop propofol and provide supportive care; IV fluids, ensuring good urine output, adequate oxygenation, dialysis (if indicated), vasopressor and inotropic support.

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Needle Decompression - Are we Teaching the Right Location?

  • Tension pneumothorax frequently results in circulatory collapse and may lead to cardiopulmonary arrest.
  • In the event that tube thoracostomy cannot be immediately performed, traditional teaching is to perform needle decompression in the second intercostal space, mid-clavicular line using a 5-cm angiocath needle.
  • Recent literature, however, has challenged the traditional location for needle decompression.  In fact, researchers found:
    • Needles placed in the second intercostal space often failed to enter the chest cavity and relieve tension physiology.
    • Needles placed in the fifth intercostal space in the anterior axillary line were more likely to enter the chest cavity with a lower failure rate.
  • Take Home Point: It may be time to reconsider the optimal position for needle decompression of tension pneumothorax.

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Category: Critical Care

Title: Hemodynamic Pearls from the Surviving Sepsis Guidelines

Posted: 1/29/2013 by Haney Mallemat, MD (Emailed: 1/30/2013) (Updated: 1/30/2013)
Click here to contact Haney Mallemat, MD

The updated Surviving Sepsis Guidelines have been released (click here) and here are some recommendations as they pertain to hemodynamic management (grades of recommendations in parenthesis).

Fluid therapy

  • An initial fluid bolus of at least 30 mL/kg is recommended; crystalloids should be the initial fluids (1B).
  • Consider albumin when “substantial” amounts of crystalloid have been given (2C).
  • Use of hydroxyethyl starch is not recommended (1B)

Vasopressors (targeting MAP of at least 65 mmHg)

  • Norepinephrine (NE) is the vasopressor of choice (1B)
  • Epinephrine (EPI) if an additional agent is required; can be added to or substituted for NE (2B)
  • Vasopressin (0.03 units/minute) can be added to NE; it should not be titrated or used as a single agent (ungraded).
  • In selected patients (e.g., bradycardia or low-risk of tachyarrhythmia), dopamine may be considered (2C). Low-dose dopamine (for renal protection) should not be used (1A).
  • Phenylephrine (PE) is not recommended, except if (1C):
    • Serious NE associated arrhythmias
    • Cardiac output can be measured and is increased with low MAP (PE can reduce cardiac output)
    • Other therapies cannot achieve the target MAP

Corticosteroids

  • Use if fluids and vasopressors cannot restore adequate perfusion
  • Total daily dose of 200 mg (2C) administered by continuous infusion (2D)
  • ACTH stimulation test is not recommended (2B)
  • Tapering hydrocortisone when vasopressors have been discontinued (2D)

Inotropic Therapy

  • Administer dobutamine if it is believed that cardiac filling pressures are elevated, cardiac output is low, or persistent signs of hypoperfusion despite other therapies (1C)

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Postintubation Hypotension

  • It is clear that preintubation hypotension is associated with increased mortality in critically ill patients who require mechanical ventilation.
  • Unfortunatley, the literature is less clear on the frequency and impact of hypotension that develops after intubation.
  • Two recent publications in the Journal of Intensive Care provide valuable information on postintubation hypotension.  Some highlights of the studies include:
    • Retrospective cohorts of over 300 patients who developed postintubation hypotension, defined as a SBP < 90 mm Hg within 60 min of intubation.
    • Postintubation hypotension occurred in almost 25% of patients.
    • Median time to hypotension was 11 minutes.
    • Patients with postintubation hypotension had a higher inhospital mortality (33% vs. 23%).
    • A preintubation Shock Index > 0.8 was the strongest predictor of cardiovascular collapse after intubation.
  • Take Home Point: Postintubation hypotension occurs frequently and may be associated with worse outcomes.

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Intra-aortic balloon pumps (IABP) are devices that provide hemodynamic support during cardiogenic shock; the balloon inflates during diastole (improving coronary artery perfusion) and deflates during systole (reducing afterload and improving systemic perfusion). Click here to see a 41 second video illustrating how it works. 

Several guidelines recommend placement of an IABP for patients in cardiogenic shock secondary to acute myocardial infarction (AMI), if early revascularization (e.g., CABG) is planned (Class I recommendation). Data behind this recommendation, however, is limited.

The IABP-SHOCK II trial was a randomized, multi-center, open-label study that enrolled 600 patients (598 in the analysis) with cardiogenic shock secondary to AMI (STEMI or NSTEMI). Patients were randomized to the control group (receiving standard therapy; N=298) or the experimental group (receiving IABP; N=300).

No significant difference was found between groups with respect to 30-day mortality (primary end-point), secondary end-points (e.g., time to hemodynamic stabilization, renal function, lactate levels, etc.), or complications (e.g., major bleeding, peripheral ischemic complications, etc.).

Bottom line: Perhaps it is time to reassess the approach to cardiogenic shock secondary to AMI when early revascularization is planned. At this time consultation with local expertise is recommended.

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The Crashing Cardiac Transplant Patient

  • Approximately 2000 patients receive a cardiac transplant each year in the United States.
  • With improvements in surgical techniques, immunosuppression, and management of complications, graft half-life is now approximately 13 years; thereby increasing the likelihood that a cardiac transplant patient will show up in your ED. 
  • In the crashing cardiac transplant patient, think of the following causes for acute decompensation:
    • Acute rejection
    • Primary graft failure
    • RV failure
    • Sepsis
  • For patients with primary graft failure initiate inotropic support with dobutamine, epinephrine, milrinone, or isoproteronol.  Those failing standard inotropes will likely require mechanical circulatory support (VAD) or ECMO.
  • Patients with acute RV failure will often require the combination of a pulmonary vasodilator (inhaled NO, prostaglandins) and inotropic agent. In addition, it is critical to avoid hypercapnia and hypoxia.  

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DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) or DIHS (Drug-Induced Hypersensitivity Syndrome) is a potentially life-threatening adverse drug-reaction.

Incidence is 1/1,000 to 1/10,00 drug exposures. It occurs 2-6 weeks after the drug is first introduced, distinguishing it from other adverse drug-reactions which typically occur sooner.

The syndrome classically includes:

  • Severe skin eruptions (typically morbilliform or erythrodermic eruptions)
  • Hematologic abnormalities (eosinophilia or atypical lymphocytosis)
  • Organ involvement; e.g., hepatic (most common), pneumonitis, renal failure, etc.
  • Fevers
  • Arthralgia
  • Lymphadenopathy

The most commonly implicated drugs are anticonvulsants (e.g., carbamazepine, phenobarbital, and phenytoin), sulfonamides, and allopurinol. 

Recovery is typically complete after discontinuing the offending drug; systemic steroids may promote resolution of the illness.

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VV-ECMO for Refractory Hypoxemia

  • In the absence of significant cardiac disease, patients with refractory hypoxic respiratory failure should be considered for venovenous extracorporeal membrane oxygenation (VV-ECMO).
  • Though indications vary slightly among organizations, the Extracorporeal Life Support Organization states that ECMO is indicated when the PaO2/FiO2 is < 80 mm Hg on FiO2 > 90% or safe plateau pressures (< 30 cm H2O) cannot be maintained.
  • A few pearls when initiating VV-ECMO:
    • Fluids are often needed in the first few hours after initiation of ECMO
    • Reduce tidal volumes to maintain plateau pressures < 25 cm H2O
    • Decrease FiO2 to maintain oxygen saturations > 88%
    • Use a hemoglobin threshold of 7-8 g/dL for blood transfusion

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Management of patients with severe traumatic brain injury (TBI) typically involves the use of invasive intra-parenchymal pressure monitors. Although use of these monitors is recommended by TBI management guidelines, good quality evidence of benefit is lacking.

A recently published study evaluated the outcomes of TBI patients using a management protocol incorporating either an intracranial pressure (ICP) monitor compared to use of the clinical exam PLUS serial neuroimaging; a total of 324 patients were prospectively randomized into either group.

The primary study outcome was a composite of survival, impaired consciousness, and functional status at both three and six months.

The results of the study did not show a significant difference in the:

  • Primary outcome  
  • Median length of ICU stay
  • Distribution of serious adverse events

Bottom line: This study suggests that clinical exam PLUS serial neuroimaging may perform as well as invasive intra-parenchymal monitors for guiding therapy in TBI patients.

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Ultrasound-Guided Pericardiocentesis

  • Though emergent pericardiocentesis is a relatively rare procedure in the ED, it is a critical intervention in patients with effusion and life-threatening instability/PEA arrest.
  • Ultrasound-guided pericardiocentesis is preferred over the traditional "blind" approach, as it allows the provider to choose an optimal position and is associated with fewer complications.
  • A few pearls when using ultrasound for emergent pericardiocentesis:
    • Consider placing an NGT for abdominal decompression.
    • Don't mistake the epicardial fat pad for an effusion; fat pads don't change size and usually move in concert with the ventricle.
    • The apical 4-chamber view tends to be the most common probe position, as the largest collection of fluid is usually around the apex.
    • If you are unsure about your needle location, inject 5-ml of agitated saline to confirm you are in the pericardial space.

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Category: Critical Care

Title: Labs in Anaphylaxis

Keywords: anaphylaxis, tryptase, diagnosis (PubMed Search)

Posted: 12/6/2012 by Ellen Lemkin, MD, PharmD (Updated: 1/27/2023)
Click here to contact Ellen Lemkin, MD, PharmD

  • Serum total tryptase measurements may be useful for confirmation of venom or drug induced anaphylaxis (not as useful for food induced)
  • Can send serial tryptase levels at the time of presentation, 1-2 hours later, and at resolution
  • This is NOT helpful for confirmation at the time of the episode, as it takes several hours to perform

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Category: Critical Care

Title: Management of AKI

Posted: 11/27/2012 by Mike Winters, MD (Updated: 1/27/2023)
Click here to contact Mike Winters, MD

Managing Critically Ill Patients with AKI

  • Acute kidney injury (AKI) occurs in almost 50% of hospitalized patients and is an independent risk factor for mortality. 
  • Updated guidelines have recently been published on the management of patients with AKI.
  • Pearls for the management of patients with, or at risk of, AKI include:
    • Optimize volume status and perfusion pressure
      • Crystalloids preferred over colloids
      • Consider vasopressors to maintain MAP > 65 mm Hg
    • Avoid nephrotoxic drugs
    • Control co-factors
      • Monitor intra-abdominal pressure
      • Avoid hyperglycemia - target glucose < 150 mg/dL

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A low-tidal volume (or protective) strategy of mechanical ventilation (i.e., tidal volume of 6-8cc/kg of ideal body weight) has previously been demonstrated to be beneficial in patients with acute respiratory distress syndrome (ARDS).

A meta-analysis was recently performed to determine whether this strategy of mechanical ventilation is also beneficial for patients without lung injury prior to initiation of mechanical ventilation.

Dr. Neto, et al. performed a meta-analysis of 20 studies (total of 2,822 mechanically ventilated patients) comparing a conventional ventilation strategy (average tidal volume was 10.6 cc/kg) to a protective ventilation strategy (average tidal volume was 6.4 cc/kg) of mechanical ventilation.

The authors concluded that patients ventilated with a protective lung-strategy had reductions in:

  • Mortality
  • Lung injury and ARDS
  • Atelectasis
  • Pulmonary infections          
  • Length of hospital stay

Bottom-line: This meta-analysis supports the notion that a strategy of low-tidal volume ventilation may have benefits for patients without ARDS, however prospective studies are needed.

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Burn Patients and Antibiotic Dosing

  • Burn patients have a number of abnormalities in the early postinjury phase that can significantly impact the efficacy of antimicrobial therapy.  These include hypovolemia, hypoalbuminemia, and increasing GFR.
  • A few pearls when dosing select antibiotics in burn patients:
    • Aminoglycosides: in the absence of renal impairment, consider more frequent dosing to achieve adequate concentrations.
    • Beta-lactams: typical doses often don't reach effective concentrations; increase the dose, frequency of administration, or duration of infusion.
    • Vancomycin: the typical dose of 1 gm is usually ineffective; use a larger loading dose (15-20 mg/kg).
    • Linezolid: standard doses are usually ineffective; use a higher initial dose.

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Previous pearls have described the increasing evidence against colloid (e.g., hydroxyethyl starch) use during resuscitation. Now it appears that the crystalloid 0.9% normal saline (NS) may be under fire. 

The use of large volumes of NS has been associated with hyperchloremic metabolic acidosis and harm in animal studies. The risk of harm in humans, however, has been less clear. 

Bellomo et al. conducted a prospective observational study in which patients being resuscitated in the control group received NS at the clinicians' discretion; i.e., chloride-liberal strategy. The use of NS was restricted in the intervention group, where other less chloride containing fluids were used for resuscitation (e.g., Ringer's Lactate); i.e., a chloride-restrictive strategy. 

The authors found that when compared to patients in the chloride-liberal group, the chloride-restrictive group had significantly less rise in baseline creatinine, less overall AKI, and a reduced need for renal replacement therapy.

Bottom line: Although this was only an observational study, the liberal use of normal saline during resuscitation may increase the risk of AKI and renal replacement therapy. 

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Category: Critical Care

Title: Serotonin Toxicity

Posted: 10/30/2012 by Mike Winters, MD (Updated: 1/27/2023)
Click here to contact Mike Winters, MD

Serotonin Toxicity in the Critically Ill

  • Serotonin toxicity (aka serotonin syndrome) can easily be overlooked and misdiagnosed in many of our critically ill patients.
  • Several common ED medications are associated with serotonin toxicity and include tramadol, linezolid, ondansetron, and metoclopramide.
  • Clues to the diagnosis include hyperthermia, increased muscle tone, hyperreflexia, dilated pupils and clonus.  Of these, clonus is the most sensitive and specific sign.
  • A few important treatment pearls:
    • Avoid physical restraints
    • Consider cyproheptadine: only available in PO form; initial dose is 12 mg
    • Avoid dopamine for those that need vasopressors
    • Avoid bromocriptine and dantrolene

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