UMEM Educational Pearls - By Mike Winters

Post-Arrest Tidal Volume Setting

• Most patients with ROSC from out-of-hospital cardiac arrest undergo endotracheal intubation and mechanical ventilation.
• Optimal management of mechanical ventilation for the post-arrest patient is currently not well defined.
• A recent retrospective cohort study sought to determine if a lower tidal volume (Vt) was associated with improved neurocognitive outcome at hospital discharge.
• Of 256 patients included in the study, investigators found:
  • 38% were ventilated with Vt > 8 ml/kg predicted body weight
  • Lower Vt was significantly associated with favorable neurocognitive outcome, decreased duration of mechanical ventilation, and decreased ICU length of stay
• Take Home Pearl: Pay attention to Vt in the post-arrest patient.

Show References

Hyponatremic Encephalopathy

• Hyponatremic encephalopathy is a true emergency and due to hypoosmolar-induced cerebral edema.
• In contrast to the asymptomatic patient with hyponatremia, treatment of hyponatremic encephalopathy is determined by symptoms and not the duration of hyponatremia.
• Clinical manifestations include nausea, vomiting, headache, confusion, seizures, respiratory failure, and coma.
• Hypertonic saliine is the treatment of choice
  • Administer 2 ml/kg 3% hypertonic saline (100 ml in many cases)
  • This will typically raise serum sodium 2 mEq/L
  • In most cases, a 4-6 mEq/L rise will reverse neurologic symptoms

Show References

Improving Resuscitation Performance

• Resuscitating the critically ill patient can often be quite stressful.
• Stress has been shown to decrease the quality and effectiveness of decisions, decrease the amount of information a person can process, and lead to short-term memory deficits.
• Recently, there has been emphasis on the use of performance-enhancing psychological skills (PEPS) to allow providers to think clearly, maintain situational awareness, recall important information, and perform skills efficiently.
• A recent article highlights 4 key elements of an EM model for PEPS that can be used to improve performance in resuscitations.
  • Breathe - consider tactical breathing
  • Talk - positive instructional or motivational self-talk
  • See - visualize the steps of a procedure before actually performing it
  • Focus - use a trigger word as a prompt to shift attention to a prioritized task

Show References

Ventilation During Cardiopulmonary Resuscitation  

• Cardiopulmonary resuscitations are often highly stressful and chaotic situations.  As a result, it is no surprise that ventilation rates can be as high as 60 breaths per minute.  
• Hyperventilation during cardiopulmonary resuscitation can increase intrathoracic pressure, impair venous return, decrease coronary perfusion pressure, and ultimately decrease survival.
• It is imperative that the team leader pay close attention to ventilation and ensure that approximately 8 to 10 breaths per minute are delivered.
• Once ROSC is achieved, the respiratory rate should be adjusted to maintain a PaCO2 between 40 and 45 mm Hg.  

Show References

Antibiotics in Sepsis

• Currently international guidelines for the management of sepsis and septic shock recommend antibiotic administration within 1 hour of recognition.
• With the persistent problem of ED boarding, many patients with sepsis and septic shock remain in the ED long after the initial dose of broad-spectrum antibiotics.
• A recent single center, retrospective cohort study demonstrated that 1 out of 3 patients with sepsis or septic shock experienced major delays in the time to the second dose of antibiotics.  In fact, over 70% of patients who were given an initial antibiotic with a 6-hr recommended dosing interval experienced major delays.
• Inpatient boarding in the ED was found to be an independent risk factor for major delays.
• Take Home Point: Don't forget to write for additional doses of antibiotics in your boarding patients with sepsis.

Show References

Ventilator Settings for the Post-Arrest Patient

• The majority of patients with ROSC from OHCA require intubation and mechanical ventilation.
• Correctly managing the ventilator in the post-arrest patient is critical for improving outcomes.
• As patients are at high risk for ARDS, use lung-protective ventilation with tidal volumes between 6 to 8 ml/kg of ideal body weight and PEEP of 5 to 8 cm H2O.
• There is a U-shaped relationship between neurologic outcomes and both PaO2 and PaCO2.
  • Target normoxia (SpO2 94% to 96%) and avoid hyperoxia and hypoxia.
  • Target normocapnia (PaCO2 40 to 50 mm Hg) and avoid hypercapnia and hypocapnia.
• Use an analgosedation approach with short-acting analgesics and sedatives, such as fentanyl and propofol.

Show References

DSI, Ketamine, and Apnea

• In recent years, delayed sequence intubation (DSI) with ketamine has been used in select patients to maximize preoxygenation and dinitrogenation. 
• Importantly, DSI is not well studied. In the only prospective trial of DSI, patients received approximately 1.4 mg/kg of ketamine.
• Driver, et al. report the abrupt onset of apnea in a patient who received a much lower dose of ketamine (25 mg) for DSI.
• Take Home Point: If DSI is a part of your preoxygenation armamentarium, apnea can occur even at low doses of ketamine.  Stand at the patient's bedside and be ready to immediately intubate the patient.

Show References

Preoxygenation in Critically Ill Patients

• Achieving adequate preoxygenation and denitrogenation prior to intubating critically ill patients can be challenging.
• Critically ill patients have physiologic alterations (i.e., derangements in oxygen consumption, anemia, reduced cardiac output, air space disease) that can markedly reduce safe apnea time.
• For patients with significant air space disease and shunt physiology, noninvasive ventilation (NIV) can decrease shunt fraction, increase functional residual capacity, improve PaO2, and lengthen safe apnea time.
• Importantly, NIV should be used for at least 3 minutes to achieve improvements in alveolar recruitment.
• It is also important to remove NIV just prior to larygnoscopy, as alveoli will begin to derecruit when NIV is removed.

Show References

Sepsis Mimics

• Emergency physicians are well versed in the resuscitation of patients with sepsis and septic shock.
• With the recent publication of the 2016 SSC Guidelines and the emphasis in meeting various quality measures, sepsis is routinely included in the differential diagnosis of critically ill patients.
• Notwithstanding, it is important to consider other disease states that can present similarly to sepsis or septic shock.  Some of these include:
  • Anaphylaxis
  • Adrenal insufficiency
  • DKA
  • Thyroid storm
  • Toxic ingestion or withdrawal

Show References

Epinephrine in Anaphylaxis

• Delayed administration of epinephrine for patients witih anaphylaxis is associated with increased morbidity and mortality.
• Providers are often hesitant to administered epinephrine to older patients with anaphylaxis for fear of precipitating an adverse cardiovascular event.
• A recent retrospective study of almost 500 patients demonstrated that older patients were significantly less likely to receive epinephrine, despite meeting the definition for anaphylaxis.
• Furthermore, cardiovascular complications occurred in just 9 patients, 6 of which received an excessive dose via the IV route.
• Take Home Point: There are no absolute contraindications (including age) for epinephrine in patients with anaphylaxis.  Give the initial dose IM into the anterolateral thigh.

Show References

PaCO2 and the Post-Arrest Patient

• Alterations in PaCO2 are common during the post-arrest period and have been associated with worse patient centered outcomes.
• Hypercarbia can dilate cerebral vessels, increase cerebral blood flow, and may increase intracranial pressure.
• Conversely, hypocarbia can constrict cerebral vessels and may reduce cerebral blood flow.
• Though the current evidence is primarily limited to observational trials, a recent meta-analysis found that "normocarbia" was associated with improved hospital survival and neurologic outcome. 
• Take Home: Adjust mechanical ventilation to target normocarbia (PaCO2 or ETCO2) in the post-arrest patient.

Show References

Mechanical Ventilation in the Obese Patient

• Obesity can result in decreased lung volumes, decreased lung and chest wall compliance, and increased work of breathing.
• Unfortunately, there is very little literature to guide the emergency physician on mechanical ventilation in obese patients.
• A recent study of intubated ED patients by Goyal, et al found that over 1 in 5 patients were ventilated with potentially injurious tidal volumes.
• Importantly, obesity increased the odds of inappropriate ventilator settings.
• In the intubated obese patient, be sure to set tidal volume based on ideal body weight and consider starting with a higher PEEP setting (i.e., 10 to 15 cm H2O).

Show References

What Matters in Cardiac Arrest?

• Approximately 500,000 adults suffer sudden cardiac arrest each year in the United States.
• The most important components of cardiac arrest care that have been shown to improve outcomes are:
  1. High-quality CPR with little to no interruptions
  2. Defibrillation for ventricular arrhythmias
  3. Optimal post-arrest care
     • Target an SpO2 of 94-98%
     • Target an ETCO2 of 35-40 mm Hg (PaCO2 of 40-45 mm Hg)
     • Targeted temperature management
     • Early cardiac catheterization

Show References

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)

Show References

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.

Show Additional Information

Show References

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.

Show References

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.

Show References

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.

Show References

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.

Show References

Show References