UMEM Educational Pearls - Critical Care

Category: Critical Care

Title: Types of Respiratory Failure

Keywords: Respiratory failure (PubMed Search)

Posted: 6/21/2016 by Feras Khan, MD
Click here to contact Feras Khan, MD

There are 4 types of respiratory failure that all providers should be familiar with

Type 1: Hypoxemic, PaO2 <50; this can include shunt , V/Q mismatch, or high altitude. Pulmonary edema, ARDS, pneumonia are common causes of this type of failure.

Type 2: Hypercapnic respiratory failure; decreased RR or tidal volume. This includes neuromuscular disorders including GBS or Myasthenia Gravis, in addition to medication overdose. COPD and asthma can lead to this type of respiratory failure as well.

Type 3: Peri-operative; atelectasis; decreased FRC from being supine or obese during the operative period.

Type 4: Shock or hypoperfusion leading to increased work of breathing and respiratory failure.


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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  • Current guidelines recommend IV proton pump inhibitors in setting of acute upper GI hemorrhage as a bolus + infusion (e.g. 80 mg bolus + 8mg/hr infusion).
  • Recent meta-analysis comparing bolus + infusion versus intermittent bolus (most commonly 40 mg BID) demonstrated non-inferiority of intermittent bolus dosing.
  • In fact, there was a trend (though not significant) to superiority of intermittent bolus dosing, with decreases in rebleeding, mortality, repeat intervention.
  • From a practical standpoint, pantoprazole requires a dedicated IV line, and is not compatible with other common ICU infusions (fentanyl, propofol, norepinephrine, octreotide).

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  • Many clinicians use end-tidal CO2 to monitor respirations during procedural sedation or mechanical ventilation
  • Typically either the presence (or absence) of a "normal" waveform or the quantitative value is used, however a lot more information can be gathered from the actual shape of the waveform; below are a few examples.
  • For more examples of interpreting waveforms, click HERE.

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Category: Critical Care

Title: American Thoracic Society (ATS) Conference Highlights

Keywords: ATS, non invasive ventilation, aspirin, nighttime extubation, dialysis (PubMed Search)

Posted: 5/24/2016 by Feras Khan, MD (Updated: 7/18/2019)
Click here to contact Feras Khan, MD

American Thoracic Society (ATS) Conference Highlights

The ATS conference was last week in San Francisco and a few cool articles were presented. They are briefly summarized below:

1.     Using a helmet vs face mask for ARDS: Non-invasive ventilation is not ideal for ARDS for a variety of reasons. At the same time, endotracheal intubation and ventilation carries some risks as well. Could a new design of a "helmet" device make a difference? This one center study from the Univ of Chicago suggests that it would: decreased rate of intubation, increase in ventilator free days, and decrease in 90 day mortality. http://jama.jamanetwork.com/article.aspx?articleid=2522693

2.     Can aspirin prevent the development of ARDS in at risk patients in the emergency department? Unfortunately, it does not appear to help. http://jama.jamanetwork.com/article.aspx?articleid=2522739

3.     Should you start renal-replacement therapy (HD, CRRT etc) in critically ill patients with AKI sooner or later? Seems to have no difference and may actually lead to patients not needing any dialysis. Really a great read  if you have time.  http://www.nejm.org/doi/full/10.1056/NEJMoa1603017?query=OF&

4.    Should I extubate at night? Lastly, probably don’t extubate at night if you can avoid it. Or just be cautious. http://www.atsjournals.org/doi/abs/10.1164/ajrccmconference.2016.193.1_MeetingAbstracts.A6150

 


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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Category: Critical Care

Title: Zika Virus -- More than Fetal Microcephaly

Keywords: Zika, Guillain-Barre, GBS, ITP, Critical Care (PubMed Search)

Posted: 5/10/2016 by Daniel Haase, MD
Click here to contact Daniel Haase, MD

Zika virus has received significant media attention in the US due to its recent link with teratogenicity. But Zika is also associated with critical and life-threatening complications, including death. Differentiating it from other Flavivirus diseases such as Dengue or Chikungunya can be challenging.

Diagnosis

  • Clinical -- low-grade fever, maculopapular pruritic rash, arthralgias (small joints of hands and feet), non-purulent conjunctivitis [1,4]
  • Serum RT-PCR
  • Dengue --high fever, severe myalgias, no conjunctivitis, cytopenia common [2,4]
    • Dengue is a hemorrhagic fever, Zika and Chikungunya are not.
  • Chikungunya -- high fever, severe polyarthralgias, no conjunctivitis, no hemorrhage [2,4]

Complications

  • Guillian-Barre Syndrome (GBS) [1,3]
    • Responsible for majority of Zika deaths worldwide
    • Estimated at 1 in 4000 cases of Zika in French Polynesian study [3]
    • WHO estimates up to 4M cases in the Americas this year (~1k cases GBS)
  • Immune Thrombocytopenic Pupura (ITP) [2]
    • Thrombocytopenia leading to bleeding. Responsible for lone US death and deaths in Columbia
  • Meningoencephalitis, transverse myelitis, fetal microcephaly [2]

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Attachments

Zika_Dengue_Chikungunya.jpg (131 Kb)


Category: Critical Care

Title: Increasing Survival in In-hospital Cardiac Arrest

Keywords: in hospital cardiac arrest, cardiac arrest (PubMed Search)

Posted: 4/26/2016 by Feras Khan, MD
Click here to contact Feras Khan, MD

A recent survey looked at resuscitation practices that could help improve survival during in-hospital cardiac arrest

  • Monitoring for interruptions in chest compressions
  • Reviewing cardiac arrest cases monthly
  • Adequate resuscitation training

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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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Disclaimer: Talking about seizures/status that is NOT due to eclampsia

  • Propofol (Class B) -- though not recommended for obstetric use by manufacturer
  • Benzodiazepines (Class D) -- mostly due to fetal withdrawal syndrome, but some teratogenicity to prolonged exposure inconsistent in literature
  • Ketamine (No FDA class assigned but likely Class B Austrailia equivalent)
  • Levetiracetam (Class C) -- no clear evidence of major fetal malformations in humans
  • Phenytoin, phenobarbitol, carbemazepine, valproic acid and most other common AEDs (Class D due to teratogenicity)

TAKE HOME: While no AEDs are completely safe in pregnancy, treatment and stabilization of maternal status epilepticus is paramount for fetal health. Involve neurology/epileptology and OB/maternal-fetal medicine.

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  • Amiodarone and lidocaine are commonly used antiarrhythmics for ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). Their efficacy towards survival to hospital discharge and neurological outcome, however, has been questioned.
  • A recently published study in the NEJM evaluated these drugs by performing a double-blind, randomized, placebo-control trial. The trial evaluated patients presenting with out of hospital cardiac arrest secondary to VF or pulseless VT that is refractory to one or more shock.
  • The trial randomized 3,026 patients to receive amiodarone (974), lidocaine (993), or normal saline (i.e., placebo) (1,059); the primary outcome was survival to hospital discharge and the secondary outcome was favorable neurological outcome at hospital discharge. Several sub-group analyses were planned a priori.
  • No statistically significant difference was found in hospital survival or neurologic outcomes between any of the groups. Patients who had a witnessed arrest and bystander CPR had higher rates of survival with either lidocaine or amiodarone compared to saline while there was no difference between the two.

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Category: Critical Care

Title: What is cardio-renal syndome?

Keywords: cardiorenal syndrome, heart failure, kidney failure (PubMed Search)

Posted: 3/29/2016 by Feras Khan, MD
Click here to contact Feras Khan, MD

What is cardio-renal syndrome CRS?

  • Covers disorders where acute or long-term dysfunction of one organ can cause acute or long-term dysfunction of the other
  • Worsening renal failure, diuretic resistance in heart failure, and worsening kidney function during heart failure are all characteristic of the disease process

There are 5 types

1. Acute CRS: abrupt worsening of heart function leading to kidney injury

2. Chronic CRS: chronic heart failure leads to progressive kidney disease

3. Acute renocardiac syndrome: abrupt kidney dysfunction leading to acute cardiac disorder

4. Chronic renocardiac syndrome: chronic kidney disease leading to decreased cardiac function

5. Systemic CRS: Systemic condition leading to both heart and kidney disease

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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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Category: Critical Care

Title: Clevidipine for Hypertensive Emergencies

Keywords: Pharmacology, Hypertension, Vasoactive (PubMed Search)

Posted: 3/15/2016 by Daniel Haase, MD
Click here to contact Daniel Haase, MD

There are multiple vasoactive infusions available for acute hypertensive emergencies, many having serious side effect profiles or therapeutic disadvantages.

Clevidipine (Cleviprex) is rapidly-titratable, lipid-soluable dihydropyridine calcium channel blocker which has become increasingly used in the ICU in recent years [1]:

  • Onset of action 2-4 minutes
  • Duration of action 5-15 minutes (half-life of 1 minute)
  • Clevidipine is relatively inexpensive ($108/50mL bottle)
  • Side effects include hypertriglyceridemia, hypotension and reflex tachycardia

ECLIPSE trial compares clevidipine, nicardipine, nitroglycerin and nitroprusside in cardiac surgery patients. .

Clevidipine was as effective as nicardipine at maintaining a pre-specified BP range, but superior when that BP range was narrowed (also studied in ESCAPE-1 and ESCAPE2 with similar results) [2-3]

TAKE-HOME: Clevidipine is an ultra short-acting, rapidly-titratable vasoactive with favorable cost, pharmacokinetics, and side-effect profile. Consider its use in hypertensive emergencies.

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  • The RUSH exam is a rapid way to identify the cause of shock using ultrasound. What's the RUSH exam? Click here
  • The RUSH exam does not include an assessment of volume responsiveness (VR), but a new article by Blaivas, Aguiar, and Blanco suggests that it should be.
  • VR has classically been assessed by determining the stroke volume before and after a passive leg raise or a fluid bolus. Click here for a video on how to calculate the stroke volume (skip to 21:30 in the video)
  • The authors claim that VR can further be simplified by not measuring the left ventricular outflow tract (LVOT) and only comparing changes in the velocity-time integral (VTI). The assumption is that the LVOT is constant and doesn't change in most circumstances; a change of VTI that is greater than 15% suggests that the patient is VR
  • Further validation is required to determine the degree of benefit to adding VTI to the RUSH exam, however measuring VTI is a skill that can be done with relatively little training and is clinically helpful.

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  • A recent observational study was published looking at the ICU incidence and outcome of ARDS
  • This international prospective cohort study looked at 459 ICUs and over 29,000 patients
  • Incidence: 10.4% met ARDS criteria
  • Severe ARDS occurred in 23.4%
  • Clinical recognition of mild ARDS was only 51%
  • Less than 2/3rds of patients with ARDS received a TV of 8 mL/kg or less
  • Prone positioning was used in 16% of patients with severe ARDS
  • Recognition of ARDS was associated with higher PEEP, greater use of neuromuscular blockers, and prone positioning
  • Mortality ranged from 35% to 46%
  • Pneumonia was the biggest risk factor for ARDS

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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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  • Transthoracic echocardiography (TTE) is an essential tool during cardiac arrest because it identifies potentially reversible causes (e.g., tamponade, massive PE, etc.).
  • One of the limitations of TTE is that it is sometimes difficult to assess the heart in less than ten seconds (i.e., during a pulse check) and good views of the heart sometimes hard to obtain. Transesophageal echocardiography (TEE) offers the potential to overcome these obstacles.
  • TEE not only allows continuous visualization and better imaging of the heart during arrest, but it also allows the assessment of compression depth, and whether the heart is being correctly compressed during CPR.
  • Here is what a TEE probe looks like, here is an example of a TEE during arrest, and here is a podcast by @ultrasoundpodcast on the literature for using TEE during cardiac arrest.

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Category: Critical Care

Title: Acute Kidney Injury (AKI)

Keywords: aki, renal failure, acute kidney injury (PubMed Search)

Posted: 2/2/2016 by Feras Khan, MD
Click here to contact Feras Khan, MD

  • AKI can be seen in up to 40% of ICU patients
  • Around 5-10% require treatment with renal replacement therapies
  • The most common cause is acute tubular necrosis
  • Definition by KDIGO:
  1. Increase in Creatinine by 0.3 or more within 48 hours OR
  2. Increase in Cr to >1.5 x baseline, presumed to have occured within the prior 7 days
  3. Urine volume <0.5 mL/kg/hr x 6 hours

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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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