UMEM Educational Pearls - By Mike Winters

Intravascular Volume and the IVC

  • Point-of-care ultrasound (POCUS) assessments of the inferior vena cava (IVC) are frequently used in the fluid resuscitation strategy for critically ill patients.
  • Numerous factors determine the appearance of the IVC, including intraabdominal pressure, mean systemic filling pressure, central venous pressure, intrathoracic pressure, and right heart function.
  • Given these multitude of factors, it is not surprising that literature has demonstrated that the IVC is not a reliable marker of fluid responsiveness.
  • Rather, focus on the use of the IVC has shifted towards assessing fluid tolerance, venous congestion, and its use as a marker on when to stop fluid administration.
  • POCUS assessment of the IVC is commonly performed in the long axis a few centimeters distal to the diaphragm.  
  • Rola, et al. highlight that this location may be misleading and recommend  that a more appropriate assessment be a short axis scan through the entire intrahepatic segment of the IVC, while taking into account the intrapleural and intraabdominal pressures.

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Hepatorenal Syndrome

  • Emergency physicians evaluate patients with cirrhosis and ascites daily.
  • Patients with cirrhosis are particularly susceptible to acute kidney injury (AKI), which is associated with a significant increase in hospital mortality.
  • Hepatorenal syndrome (HRS) is a specific type of renal dysfunction in patients with cirrhosis and ascites.
  • The previous classification of HRS (Type 1, Type 2) has now been replaced by HRS-AKI, HRS-AKD, and HRS-CKD.
  • The diagnostic criteria for HRS-AKI include:
    • Increase in creatinine 0.3 mg/dL within 48 hrs or 50% from baseline value within the prior 7 days
    • Lack of improvement in creatinine or urine output within 24 hrs of adequate volume resuscitation
    • Absence of an alternative explanation for AKI
  • Management of HRS-AKI centers on accurate volume assessment, timely administration of a splanchnic vasoconstrictor (norepinephrine), administration of 20-25% albumin, and avoidance of additional nephrotoxins.

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Noninvasive Ventilation for Preoxygenation

  • Over 1 million critically ill patients are intubated each year in the United States.
  • Hypoxemia can occur in up to 20% of intubations and may lead to adverse outcomes such as peri-intubation cardiovascular collapse or cardiac arrest.
  • Appropriate preoxygenation is critical to increase the safe apnea time and decrease the risk of hypoxemia during rapid sequence intubation (RSI).
  • At present, the majority of critically ill patients undergoing RSI are preoxygenated with an oxygen mask.
  • In a randomized, pragmatic, parallel-group trial conducted in 7 EDs and 15 ICUs in the United States, Gibbs et al compared the use of noninvasive ventilation for preoxygenation to an oxygen mask on the incidence of hypoxemia during intubation.
  • In over 1,300 patients, the incidence of hypoxemia during the interval between induction and 2 minutes after intubation was markedly lower in patients preoxygenated with noninvasive ventilation compared to those preoxygenation with an oxygen mask.
  • Importantly, the greatest benefit to noninvasive ventilation for preoxygenation was seen in patients with acute hypoxemic respiratory failure, those requiring > 70% FiO2 prior to intubation, and those with a BMI > 30.
  • Lastly, the trial did not enroll patients who needed emergent intubation without time for at least 3 minutes of preoxygenation.

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Bag-Valve-Mask Ventilation During OHCA

  • Current OHCA resuscitation guidelines recommend a 30:2 strategy of CPR with BVM ventilations.
  • Idris and colleagues performed a secondary analysis of the Resuscitation Outcomes Consortium CCC clinical trial to determine the incidence of BVM ventilation during a 30:2 CPR strategy and assess the association of detectable ventilations with patient outcomes.
  • In 1,976 patients, the authors found that only 40% of patients had detectable ventilations (> 250 ml) in more than half of CPR pauses.
  • For those patients with detectable ventilations in more than 50% of pauses, there was an association with increased survival to hospital admission, increased survival to hospital discharge, and increased survival with favorable neurologic outcome.
  • The current study highlights the importance of proper BVM ventilation during OHCA resuscitation and the opportunity to improve performance of this vital skill.

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PEEP in the Ventilated COPD Patient?

  • Patients with acute respiratory failure secondary to COPD often have dynamic hyperinflation and intrinsic PEEP (PEEPi).
  • Both dynamic hyperinflation and PEEPi adversely effect pulmonary mechanics, markedly increase the work of breathing, impair respiratory muscle function, and can result in hemodynamic compromise.
  • It has traditionally been felt that the application of external PEEP in the intubated COPD patient may worsen hyperinflation.
  • Importantly, external PEEP has been shown to improve ventilator synchrony and decrease the work of breathing.
  • PEEPi is measured using an end-expiratory hold maneuver in a passive, relaxed patient.
  • External PEEP can then be set to approximately 70% of PEEPi, followed by frequent monitoring of plateau pressures in a volume-cycled ventilation mode.

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Acute-On-Chronic Liver Failure

  • Acute-on-chronic liver failure (ACLF) is defined as an acute deterioration of liver function in a patient with cirrhosis that is associated with organ failure and has high short-term mortality.
  • Key extrahepatic organ failures in ACLF include the renal, CNS, respiratory, circulatory, and coagulation systems.
  • With respect to CNS failure in ACLF:
    • Hepatic encephalopathy (HE) is the most common manifestation
    • A normal ammonia level makes HE unlikely
    • Benzodiazepines should be avoided
    • Primary triggers for HE include infection, GIB, and aggressive diuresis
    • Treatment of HE primarily consists of lactulose and rifaximin

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IV Fluid Resuscitation

  • IVF administration is one of the most common interventions in the resuscitation of critically ill patients.
  • The primary goals of IVFs are to augment cardiac output and increase O2 delivery.
  • The amount and type of IVF must take into account the patient's pathophysiology and type of shock.
  • Sepsis remains one of the most common causes of distributive shock in the ED and ICU.
  • Large volumes of IVF in sepsis often do not increase cardiac output and frequently lead to organ congestion.
  • Rather than a fixed dose, an individualized approach to IVFs in sepsis based on the patient's history, exam, labs, monitoring, and serial reassessments is likely to lead to better outcomes. 

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Pearls for the Patient in Cardiogenic Shock

  • Cardiogenic shock is generally defined as tissue hypoperfusion due to ineffective cardiac output.
  • Despite therapeutic advances, 30-day mortality for cardiogenic shock can reach 50%.
  • Though there are several different phenotypes and severity of staging, consider the following pearls in the initial resuscitation of patients with cardiogenic shock:
    • Early arterial line placement for accurate blood pressure monitoring.
    • Supplemental oxygen to maintain O2 > 90%.
    • NIPPV to reduce the work of breathing for patients with pulmonary edema.
    • Use of lung-protective ventilation for patients who require intubation and mechanical ventilation.
    • Vasopressor and inotrope therapy for hemodynamic support.
      • Norepinephrine is the preferred first-line vasopressor. 
      • Dobutamine or milrinone for inotrope support.
    • Early revascularization for patients with cardiogenic shock due to acute MI.

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Bicarbonate Use for Lactic Acidosis?

  • The administration of sodium bicarbonate to treat severe acidosis remains controversial and intensely debated.
  • Often, sodium bicarbonate is administered to critically ill ED patients with a lactic acidosis and pH < 7.2 while awaiting definitive therapy directed at the inciting event. 
  • Wardi and colleagues recently conducted a narrative review of the literature on sodium bicarbonate use in select critical conditions commonly encountered in the ED.
  • In their review, the authors found that sodium bicarbonate had no effect on mortality in critically ill patients with a pH < 7.2.  In addition, bicarbonate had no effect on hemodynamics in patients with a lactic acidosis receiving vasopressor therapy.
  • With the potential exception of patients with severe acidosis and AKI, the authors conclude that sodium bicarbonate is not recommended for the treatment of lactic acidosis or shock states.

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Things to Consider for Persistent or Worsening Septic Shock

  • Septic shock is one of the most common critical illnesses in emergency medicine and critical care.
  • Norepinephrine is recommended as the initial vasopressor of choice for patients with septic shock, with vasopressin or epinephrine commonly added as a second vasopressor for patients with refractory shock.
  • While vasopressors are being added and titrated, it is important to consider additional diagnoses in patients with worsening or persistent septic shock.  Some of these diagnoses include:
    • Undetected infection that requires emergent source control
    • Concomitant causes of shock: cardiogenic, PE, abdominal compartment syndrome, tamponade, adrenal insufficiency
    • Severe acidosis
    • MAP underestimation by a radial arterial line

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An Uncommon Cause of Shock

  • Sepsis is the most common cause of distributive shock encountered in the emergency department and intensive care unit.
  • Notwithstanding, it is important to consider other etiologies of shock, especially when the patient is not responding to resuscitation.
  • Adrenal crisis is one uncommon etiology of distributive shock whereby the diagnosis is often delayed.
  • Risk factors for adrenal crisis can include recent GI illness, thyrotoxicosis, recent surgery, and physical or psychological stress.
  • Patients often have nonspecific symptoms of generalized weakness, abdominal pain, vomiting, fever, and altered mental status.
  • Current guidelines recommend the administration of 100 mg of hydrocortisone in adults suspected of having adrenal crisis.   

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Transcutaneous Cardiac Pacing

  • Transcutaneous cardiac pacing (TCP) is often attempted while preparing for transvenous cardiac pacing in critically ill patients with symptomatic bradycardia unresponsive to medical therapy.
  • For TCP, pacer pads can be placed in either the anterolateral (AL) or anteroposterior (AP) positions.  
  • Current resuscitation guidelines from the American Heart Association and the European Resuscitation Council do not identify a preferred pacer pad placement for TCP.
  • In a recent study of patients who received TCP following cardioversion from atrial fibrillation or flutter, Moayedi and colleagues found that pacer pads placed in the AP position required less mA to capture and chest wall contractions were less severe when compared to the AL position.
  • In fact, capture was approximately 80% more likely with pacer pads placed in the AP position compared to the AL position.
  • Take Home Point: Consider placing the pacer pads in the AP position the next time you need to initiate TCP.

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Optimal Timing of Source Control in Sepsis

  • Sepsis is the most common critical illness encountered in the emergency department.
  • Much of the resuscitation of patients with sepsis is focused on early and appropriate antibiotic administration, appropriate fluid resuscitation, vasopressor support, and continued hemodynamic monitoring.
  • Another critical pillar in sepsis resuscitation is source control.  To date, there is varying literature on the optimal timing of source control in sepsis.
  • In a recent cohort study of approximately 5,000 patients with community-acquired sepsis, Reitz and colleagues report a 29% reduction in risk-adjusted odds of 90-day mortality for patients who had early source control (< 6 hours) compared to those with late source control (6-36 hours).
  • The greatest reduction in risk-adjusted 90-day mortality with early source control occurred in patients with gastrointestinal/abdominal and soft-tissue sources of infection.
  • Take Home Pearl: Early source control matters in sepsis resuscitation, especially in sicker patients with a GI or soft-tissue source of infection.

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Diastolic Blood Pressure

  • The diastolic blood pressure (DBP) is determined by vascular tone and remains relativley constant throughout the arterial system.
  • A low DBP (< 50 mm Hg) suggests vasodilation and may be associated with an increased risk of myocardial ischemia and left ventricular dysfunction.
  • In a recent trial, Ospina-Tascon and colleagues described the diastolic shock index (heart rate/DBP) and found that a DSI > 2.2 was associated with higher mortality in patients with septic shock.
  • Take Home Point: pay attention to the DBP and, when low, consider initiation of vasopressors concomitant with fluid resuscitation.

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Vasopressor Tips in the Critically Ill

  • Critically ill patients often require the administration of vasopressors to maintain adequate organ perfusion.
  • A few tips to consider when administering vasopressors include:
    • Titrate to mean arterial blood pressure (MAP) or diastolic blood pressure goals.  Systolic blood pressure (SBP) is not a key driver of perfusion pressure.
    • As vasopressors also result in venoconstriction and can increase venous return, early initation may limit the need for overly aggressive fluid resuscitation.
    • Vasopressors can be safely administered through an appropriately placed peripheral venous catheter.
    • There is no maximal dose of vasopressors.
    • Consider vasopressors with a different mechanism of action in patients with persistent shock refractory to the initial vasopressor agent.

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ED Low-Tidal Volume Ventilation

  • Low-tidal volume ventilation (LTVV) reduces mortality in patients with ARDS and may reduce mortality in patients without ARDS.
  • Recent literature has highlighted the importance of initial ED ventilator settings, as these often persist for many hours after ICU admission.
  • But..does the use of LTVV in the ED really make a difference?
  • A recent systematic review and meta-analysis sought to evaluate the use of LTVV in the ED and the impact upon clinical outcomes.
  • In short, the use of LTVV in the ED was associated with an increase in the use of LTVV in the ICU, decreased occurrence of ARDS after admission, shorter ICU and hospital lengths of stay, decreased duration of mechanical ventilation, and decreased mortality.
  • Take Home Point:  The use of LTVV in the ED makes a difference!

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Hyperglycemic Hyperosmolar State (HHS)

  • Though less common, HHS has a mortality rate that is 10x greater than DKA.
  • The hallmark features of HHS include severe hyperglycemia (> 600 mg/dL), hyperosmolality (> 320 mOsm/kg), minimal to no ketosis, and severe dehydration.
  • Though the management of HHS is similar to DKA and includes fluid resuscitation, correction of hyperglycemia, and correction of electrolyte abnormalities, it is important to also monitor serum osmolality.
  • Too rapid correction of serum osmolality can cause cerebral edema and worsen patient outcomes.
  • Current recommendations are to monitor serum osmolality every 1-2 hours with a correction of no more than 3 mOsm/kg/hr.

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The BOUGIE Trial

  • More than 1 million patients undergo endotracheal intubation each year in the US.
  • Up to 20% of intubations fail on the first attempt, thereby increasing the risk of adverse outcome.
  • Over the past several years, many have become comfortable using the bougie as a rescue device when the first attempt at intubation fails with an endotracheal tube with stylet.
  • In contrast to its use as a rescue device, should the bougie be used during the first attempt rather than an endotracheal tube with a malleable stylet?
  • The BOUGIE Trial compared the effect of using the bougie to an endotracheal tube with stylet on first attempt success in critically ill patients.
  • The trial enrolled 1106 patients in 7 EDs and 8 ICUs at 11 hospitals.
  • The primary outcome of first pass success was not statistically different between those randomized to bougie and those randomized to endotracheal tube with stylet for the first attempt at intubation.. 
  • Though the trial did not find a statistical difference in first pass success rates, the bougie remains an important device in our management of the critically ill airway.

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Initial Mechanical Ventilation Settings for the Intubated Asthmatic

  • Approximately 2% of adult patients who present with an acute asthma exacerbation will require intubation and mechanical ventilation.
  • It is critical to provide the intubated asthmatic with sufficient time for exhalation.
  • Initial recommended settings for mechanical ventilation include:
    • Tidal volume: 6-8 ml/kg ideal body weight
    • Respiratory rate: 6-10 breaths per minute
    • PEEP: 0-5 cm H2O
    • Inspiratory flow rate: 80-120 L/min
  • Permissive hypercapnea is tolerated to a pH of approximately 7.15

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Management of Intermediate-High Risk PE Patients

  • Though there are varying definitions, intermediate-high risk patients with a PE are generally defined as those who are hemodynamically stable, have radiographic or laboratory evidence of right heart strain, and an elevated PE risk score.
  • A few key management pearls include:
    • Be judicious with IVFs to avoid worsening septal shift and fruther decreases in LV cardiac output.
    • Consider dobutamine for severe RV dysfunction.
    • Administer norepinephrine, if needed, to achieve a MAP of 65 mm Hg.
    • Avoid initiation of positive pressure ventilation, if possible. 
    • If intubation is needed for clinical deterioriation avoid propofol for RSI.  Propofol has been associated with increased mortality in this patient population.

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