The Role of the CVP in a Post- “7 Mares” Era
 

The role for using central venous pressure (CVP) as a measure of volume responsiveness has largely fallen out of favor over the years.¹ There are certainly better indices for fluid responsiveness, but don’t be fooled – the CVP isn’t a one trick pony.  In fact, a high or rapidly rising CVP should raise a significant concern for impending cardiovascular collapse.

Consider the following differential diagnosis in the patient with an abnormally high or rising CVP ( >10 cm H₂O).

• Excessive pressures outside of the heart or impediments to venous return (juxta-cardiac pressures)
  • Cardiac tamponade
  • Auto PEEP or breath stacking during mechanical ventilation
  • Tension pneumothorax
• Venous return that’s more than the right ventricle can handle
  • RV failure
  • Severe tricuspid valve disease
  • Massive increase in pulmonary vascular resistance (massive PE, pulmonary hypertension, ARDS, LV failure)

Bottom Line: In a time where the utility of the CVP has been largely dismissed, remember that an abnormal CVP offers great deal of information beyond a simple measure of volume status.

References

1. Marik PE, Baram M, Vahid B. Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares. Chest. 2008;134(1):172-8.
2. Berlin DA, Bakker J. Starling curves and central venous pressure. Critical Care. 2015;19(1):55.

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Updates in preventative strategies in the ICU

Preventing Ventilator Associated Pneumonia (VAP)

• Traditionally ICUs use techniques such as head of bed elevation> 30 degrees, chlorhexidine mouth rinses, reduced sedation, and controlling cuff pressure between 20-30 cm H2O to reduce VAP
• A new trial confirms that subglottic suctioning also reduces VAP
• Endotracheal tubes are made with a suction line along the edge with fenestrations below the vocal cords and above the cuff
• This is hooked to wall suction removing secretions before they are aspirated
• VAP rates are very low in the US (most likely due to under-reporting)
• It is reported at around 15 VAPs/ 1000 ventilator days in Europe

The trial

• 5 ICUs in Belgium; 352 total patients with suctioning vs control were randomized
• Reduced incidence of confirmed VAP 9% vs 18%, decrease ventilator days 10 vs 20 and antibiotic use 7% absolute reduction

Bottom Line

• More expensive around $20 or more vs $1 for a regular ETT
• NNT around 11 to prevent one VAP: it is cost efficient
• Use them in patients who will remain intubated for > 48hrs (not elective surgical patients)

Daily bathing with chlorhexidine does not reduce health care associated infections

• It is believed that daily bathing with chlorhexidine antibiotic washes decrease rates of infection in the ICU; this is debatable

The trial

• One center, 5 ICUs, 9340 patients
• 10 week cleaning period followed by a two week washout then crossover to the alternate treatment (non-antibiotic washes)
• Looking for CLABSIs, CAUTIs, VAP and C. diff infections
• 55 infections occurred in the chlorhexidine group; 60 in the control goup.
• 2.86 per 1000 patient days (chlorhexidine group) vs 2.9 per 1000 patient days (control)

Bottom Line

• Does not appear to be helpful (perhaps specific patient groups such as bone marrow units may benefit)
• More expensive to use these washes and can lead to resistance
• Very well designed study with a variety of ICUs used (although one center)

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Hypertensive Emergency Pearls

• It is well known that a hypertensive emergency is not defined by an arbitrary blood pressure reading.  Rather, it is characterized by the presence of end-organ dysfunction, often due to a sudden increase in sympathetic activation.
• When treating patients with a hypertensive emergency, consider the following:
  • Many are hypovolemic due to a pressue-induced natriuresis - give them fluids and avoid diuretics.
  • BP should be reduced in a controlled manner using short-acting titratable intravenous agents. Rapid reductions in BP can lead to organ hypoperfusion.
  • Avoid oral, sublingual, and transdermal medications until end-organ dysfunction has resolved.
  • Clevidipine is the newest agent
    • A third-generation dihydropyridine
    • Relaxes arteriolar smooth muscle
    • Rapid onset (2-4 min) and short acting (5-15 min)
    • Compares favorably with nicardipine in available studies

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Extracorporeal Treatment Strategies for Acute Methanol Poisoning (When to Dialyze)

Methanol toxicity is classically included in the differential for the intoxicated patient presenting to the ED. Add a negative EtOH level, anion/osmolar gap, blindness and you have yourself a slam dunk diagnosis. The goal is to stop the liver from metabolizing methanol to formic acid. Outside of fomepizole (or old school ethanol therapy), dialysis is often discussed, but when should you actually get the nephrologist on the phone?

This month the Extracorporeal Treatments in Poisoning Workgroup released a systematic review and consensus statement to help clinicians decide when to pull the HD trigger. Their suggestions are below.

When to start HD:

1. Neurologic dysfunction: Coma, seizures, new vision deficits
2. Metabolic acidosis: blood pH ≤7.15 or persistent metabolic acidosis despite adequate supportive measures & antidotes
3. Serum anion gap higher than 24 mmol/L
4. Serum methanol concentration:
   • > 700 mg/L (21.8 mmol/L) if fomepizole therapy is given
   • > 600 mg/L or 18.7 mmol/L if ethanol treatment is given
   • > 500 mg/L or 15.6 mmol/L in the absence of an alcohol dehydrogenase blocker

Which Modality: Intermittent HD (IHD) should be used over continuous renal replacement therapies (CRRT), as you can clear the toxin faster with higher HD flows.

When to stop HD: Extracorporeal treatment can be terminated when the methanol concentration is less than 200 mg/L or 6.2 mmol/L and a clinical improvement is observed.

Bottom Line:  Consider early hemodialysis in most patients presenting with methanol toxicity.  Clinical exam and routine lab testing will likely provide enough information to determine the need for IHD, but specific methanol levels can be helpful to guide adjunctive treatment options.

Reference

Roberts DM, Yates C, Megarbane B, et al. Recommendations for the Role of Extracorporeal Treatments in the Management of Acute Methanol Poisoning: A Systematic Review and Consensus Statement. Crit Care Med. 2015;43(2):461-472.

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• Intraosseous (IO) is well-recognized as a venous line for delivering a variety of medications, including vasopressors. However, there is not a wealth of literature to support the use of IOs when administering medications for rapid sequence intubation (RSI).
• This prospective observational study was conducted to determine whether an IO can be used to reliably and rapidly administers medications during RSI in trauma patients.
• Thirty-four trauma patients were enrolled in the study and patients had a variety of traumatic mechanisms; blunt, penetrating, burns, and blast. The primate study outcome was the success rate of first-pass intubations using direct laryngoscopy.
• The authors demonstrated a first pass success rate of 97% with a grade I view on 91% of attempts.
• Bottom-line: This is yet another study demonstrating that when rapid and reliable access is needed, IO is an excellent option for venous access.

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Diaphragm weakness and its significance

• Acute respiratory failure is partially due to respiratory muscles inability to meet the demands of respiration that is strained by a medical condition
• Ventilation can have an adverse effect on respiratory muscles even after just 5-6 days (atrophy)

There are several ways to monitor diaphragm strength and function

• Airway pressure and flow waveforms
• Occlusion pressure
• Esophageal pressure waveforms
• Sniff maneuvers
• Ultrasound
• Diaphragm EMG
• Chest xray

Clinical Relevance

• Goal is to use these devices to limit the development of respiratory muscle atrophy because of disuse
• Prevent "overassist" from the ventilator
• Potential use in weaning trials to evaluate for respiratory muscle performance
• This is a new area of intensive care research that could lead to improvements in outcomes

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"PQRST" - Capnography in Cardiac Arrest

• Resuscitation of the patient in cardiac arrest can be stressful, chaotic, and variable depending on the setting.
• Capnography is a valuable tool in the management of patients in cardiac arrest.
• Heradstveit, et al. published a pneumonic for the use of capnography during cardiac arrest:
  • P - Position of the tube
    • The sensivity and specificity of capnography for endotracheal tube confirmation is superior to auscultation and capnometry.
  • Q - Quality of CPR
    • Early detection of poor-quality compressions.
  • R - ROSC
    • A sudden increase in end-tidal CO2 can indicate ROSC without interrupting CPR for pulse checks.
  • S - Strategy
    • May assist clinicians in determining underlying etiology of cardiac arrest.
  • T - Termination
    • An end-tidal CO2 value < 10 mm Hg after 20 min of resuscitation has been shown to be very accurate in predicting death.

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Cartoons Kill: A new high-risk patient for critical illness & death

This past month, the BMJ published an impressive retrospective review that analyzed nearly 80 years of data to find that animated characters in children’s films are in fact at a very high-risk for death when compared to characters in adult dramas.

Films ranged from 1937 (Snow White) to 2013 (Frozen) and were compared against the two highest gossing dramatic films in that same year.  The authors found that nearly two thirds of the children’s animated films contained an on-screen death of an important character compared to only half in adult dramas. 

Fatalities were most commonly the result of:

• Defenestration/falls (11%)
• Animal attacks (11%)
• Drowning (6.7%)
• Gunshot wounds (6.7%)
• Other mystical causes (6.7%)

Other high-risk animated characters include the parents of the protagonist (17.8% mortality) and nemeses (28.9% mortality).  Median survival time was approximately 90 minutes (much less than the usual ED LOS!)

Notable early on-screen deaths included Nemo’s mother being eaten by a barracuda 4 minutes into Finding Nemo, Tarzan’s parents being killed by a leopard 4 minutes into Tarzan, and Cecil Gaines’ father being shot in front of him 6 minutes into The Butler.

The author’s intention  was to point out the psychological impact of death on young children, but I think the authors also highlight an important, high-risk patient population that could present to your ED.

Bottom Line: Animated characters should be aggressively resuscitated and strongly considered for admission to a higher level of care should they present to your ED, as they appear to be at high-risk for death and rapid decompensation.

May all of you have a happy and safe 2015!

Reference

1. Colman I, Kingsbury M, Weeks M, et al. CARTOONS KILL: casualties in animated recreational theater in an objective observational new study of kids' introduction to loss of life. BMJ. 2014;349:g7184.

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Treating ischemic strokes with interventional therapies (e.g., clot retrievers, stents, intra-arterial tPA, etc.) is nothing new, but there has never been a randomized control trial demonstrating benefit until recently.

The prospective MR CLEAN trial evaluated whether interventional therapies (i.e., either mechanical intervention or intra-arterial tPA) would confer benefit; patients were included if there was an acute occlusion within the proximal intracranial portion of the anterior cerebral circulation.

90% of patients received alteplase prior to randomization; there were 233 patients in the intervention group (alteplase + intraarterial intervention) and 267 patients in the usual care care arm (alteplase only); all patients were treated within 6 hours of symptoms onset

The primary outcome was functional independence at 90 days; an absolute difference of 13.5 percentage points favoring the intervention group was found. There were no significant differences in mortality or symptomatic intracerebral hemorrhage.

Despite these exciting results, we must pause and ask why this was this the first randomized trial demonstrating benefit when previous trials could not? Here are three blogs posts that deep dive this question and raise even more questions:

• EM Nerd
• Emergency Medicine Literature of Note
• St. Emlyn's

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How does it present?

• Fever, cough, sore throat, runny nose, muscle aches, headaches, fatigue, diarrhea (in children especially)

Who cares…I got my vaccine! Does the vaccine work this year?

• There has been some antigenic drift this year in the influenza A (H3N2) type virus.
• 52% are anti-genically different than the H3N2 vaccine virus.
• So the vaccine is less effective this year but it can give some cross-protection (in addition to protection against the other strains used in the vaccine)
• CDC recommends still getting the vaccine  (http://www.cdc.gov/flu/protect/vaccine/vaccines.htm)
• 91% of samples reported to the CDC have been influenza A this year

Can I test for this?

• Rapid influenza diagnostic tests check for antigen detection
• Pooled sensitivity of 62%; specificity of 98%
• False negatives are common
• Good technique during sample collection is important

The CDC is recommending treatment...wait I thought we were done with Tamiflu?

• Benefits: shortens the duration of symptoms (day or less), reduces the risk of complications, reduces the risk of death among hospitalized patients
• Risks: side effects (see below)
• A recent Cochrane review revealed that treatment did not really help reduce complications and most of the data on anti-viral agents is biased (Roche funded) and hotly debated

Who is at risk/who deserves consideration for treatment?

• Hospitalized patients with influenza 
• Old people (>65)
• Children
• Pregnant women
• Chronic medical conditions (asthma, COPD, diabetes, or heart disease)
• American Indians and Alaskan natives
• Chronic immunosuppression
• Institutional outbreaks (nursing homes, correctional facilities)

Pearls of treatment

• Treat as early as possible (<48hours from symptom onset)
• 5 days of treatment; twice daily dosing. Wt based for children. Renally dosed.
• Oseltamivir: used for more severe influenza cases
• Zanamivir: 7 years or older; IV Zanamivir is currently in Phase III clinical trials

What are the side effects of anti-viral agents?

• Don’t use zanamivir in patients w/ pulmonary disease
• Transient neuropsychiatric events for oseltamivir
• Nausea, vomiting, diarrhea are common both both

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The Critically Ill Patient with Ebola Virus Disease

• The current outbreak of Ebola Virus Disease (EVD) is the largest ever recorded and has been declared "a public health emergency of international concern" by the WHO.
• Pearls regarding critically ill patients within the current EVD outbreak include:
  • Clinical Features
    • Tachycardia, tachypnea, oliguria, and alterations in mental status are common and generally seen about 7-12 days after symptom onset.
    • Shock is often due to profound hypovolemia from GI losses.
    • Hemorrhage is a late finding and most often manifests as lower GIB.
  • Labs
    • Common lab abnormalities include hypokalemia, hypocalcemia, hypoalbuminemia, and lactic acidosis.
  • Treatment
    • The mainstay of treatment is aggressive fluid resuscitation and electrolyte repletion (especially potassium).
    • Blood products can be administered for those with coagulopathy and hemorrhage.
    • Empiric antibiotics and antimalarial medications should be considered while awaiting confirmatory testing for EVD.

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Dynamic Measures of Intravascular Volume Assessment

The resuscitation of a patient in shock often requires the administration of intravenous fluid.  Excessive fluid resuscitation can lead to worsening pulmonary edema, systemic edema, acid-base disturbances, as well as many other complications. There are a myriad of techniques to try and figure out if the patient needs more intravascular volume, but each has it’s pitfalls.

Recently, experts have recommend that we move away from using static measures of preload assessment such as central venous pressure (CVP) and instead focus on using dynamic measures for volume responsiveness.

Volume Responsiveness Defined: An increase of stroke volume of 10-15% after a 500 mL IV crystalloid bolus over 10-15 minutes.

Below is a chart describing key values, requirements, and contraindications for each of these dynamic measures of non-invasive intravascular volume assessment. 

Important notes:  PPV and SVV require the patient to be intubated with controlled tidal volumes.  Arrhythmias and right heart failure make many of these measures invalid (except for PLR).  Other methods of assessment not discussed include systolic pressure variation, left ventricular outflow track velocity time integral (LVOT VTI), and end-expiratory occlusion pressure (EEO).

Bottom Line: None of these measures are perfect and shouldn't be used in isolation to determine if the patient’s “tank is full”.  Combine clinical judgment with these measures to get a best estimate of whether or not to give that next fluid bolus.  

Reference

1. Enomoto TM, Harder L. Dynamic indices of preload. Crit Care Clin. 2010;26(2):307-21, 

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Running a successful resuscitation not only means doing everything right, but also remembering all the things that can go wrong. A.E.I.O.U. is a simple mnemonic that can help you remember the simple things that are sometimes forgotten during a medical resuscitation.

A – Advanced airway equipment to bedside, as well as checking the correct placement of the Airway if a patient is intubated in the field. Also consider adding another A, for Arterial line; early placement can help with pulse checks and an accurate assessment of blood pressure should there be return of spontaneous circulation (ROSC); the femoral site is fast and accurate.

E – End-tidal CO₂ (ETCO₂) helps detect ROSC. Ask for the ETCO2 monitor to be set up right after you receive notification of an arrest in transit; ETCO2 requires time to set-up / calibrate

I – Intraosseous line(s); compared to peripheral or central venous access, IO’s are faster, safer, and any medication can be administered through it, including vasopressors / inotropes.

O – Order (i.e., “who’s who in the Resus room?); You may be the team leader or you may be assisting, but it is important that you, and everyone else in the room, know their role prior patient arrival. If you are leading the resus, be sure everyone knows who you are, and assign everyone in the room a specific task (e.g., chest compressions, IO placement, etc.). If you are assisting and have not been assigned a task, ask the resus leader what you can do to help. If there is nothing immediate for you to do then take the initiative to de-clutter the room and step outside; be nearby and ready to help, if needed.

U – Ultrasound; can help prognosticate and detect reversible causes (e.g., pericardial tamponade). Have the ultrasound machine in the room prior to patient arrival. It should be powered on, with the proper probe connected, and in the proper mode. The most experienced ultrasonographer should scan the patient during a pulse check; experience is vital because hands-off time should be minimized.

*Tips for the Resuscitationist (#TFTR) is a new series to help you to better manage your critically ill patients. Do you have an idea for a topic or do you have a tip you would like to share? Send it to us via twitter @criticalcarenow (use (#TFTR)). You can also email us here. 

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Tips for the inpatient management of community acquired pneumonia

• The best scoring system is the Pneumonia Severity Index (PSI) for deciding on ICU admission and inpatient treatment. You can also use the CURB-65 score or the SMART-COP score but these are less sensitive.
• In general, PSI score of 4 or 5 tends to require ICU admission

• No, not really. Just try to do it as fast as you reasonably can do without over-treating

• Beta-lactam plus a macrolide or a quinolone alone. These work pretty well, cure rate around 90% or so

• You can stick with a beta-lactam plus a macrolide or quinolone in some cases but should be aware of certain issues
• Consider influenza now that we have entered the flu season
• Consider Staph aureus coverage for patients with influenza or those on chronic glucosteroids. Use linezolid or vancomycin for this.
• Consider P. aeruginosa coverage in patients with COPD or bronchiectasis.

• This can vary based on clinician preference but there is good data to support treating for around 5-7 days
• Longer treatment for Staph aureus or gram negative bacilli.   

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Aminoglycosides in Critically Ill Patients

• Aminoglycosides remain an important class of antibiotics in critically ill patients, especially those infected with multidrug-resistant organisms (i.e., Klebsiella  and Pseudomonas spp.).
• Importantly, aminoglycosides are concentration-dependent antibiotics and a greatly affected by the increased volume of distribution and altered elimination commonly seen in the critically ill.
• As a result, recommended doses are often too low to be effective. 
• Initial doses of aminoglycosides should, therefore, be higher in critically ill patients.
  • Amikacin: 25-30 mg/kg
  • Gentamicin: 7-9 mg/kg
  • Tobramycin: 7-9 mg/kg
• Subsequent doses are based on drug level monitoring.

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Back 2 Basics Series: Your Simple RSI Checklist - SOAP ME

The use of a checklist during high stress medical procedures is often recommended.  Rapid sequence intubation (RSI) is a classic situation where having a checklist can ensure adequate preparation however, if you don’t have a checklist – this simple mnemonic will make sure you are well prepared for a successful intubation.

The SOAP ME mnemonic is a quick and useful technique to remember only the basics of airway management and preparation.  Always remember to also assign roles to team members and communicate clearly to maximize your chances of success.  

Choosing Wisely in the ICU

• There is a general overuse of medical tests and treatments
• This wastes healthcare resources
• The Choosing Wisely Campaign was developed to have providers of different specialties choose medical services that should be questioned

The Critical Care Societies Collaborative came up with this list for ICU providers

1.     Don’t order diagnostic tests at regular intervals (such as every day) but rather in response to specific clinical questions. Do you really need a daily INR check or CBC check in all ICU patients? Really?

2.     Don’t transfuse red blood cells in hemodynamically stable, non-bleeding ICU patients with a hemoglobin concentration greater than 7 g/dl. See last week’s Pearl!

3.     Don’t use parental nutrition in adequately nourished critically ill patients within the first seven days of an ICU stay. TPN is the Cinnamon Toast Crunch of fungi.

4.     Don’t deeply sedate mechanically ventilated patients without a specific indication and without daily attempts to lighten sedation. Use as little as possible when you can.

5.     Don’t continue life support for patients at high risk for death or severely impaired functional recovery without offering patients and their families the alternative of care focused entirely on comfort. Engage families early in the hospital stay regarding aggressive life-sustaining treatments. Get palliative care involved in the ED!

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Hemoglobin Threshold in Septic Shock

• Numerous trials have demonstrated the benefit of lower hemoglobin thresholds for blood transfusion in critically ill patients.
• The recently published Transfusion Requirements in Septic Shock (TRISS) trial evaluated the effects on mortality of a lower versus higher hemoglobin threshold in ICU patients with septic shock.
• The TRISS trial randomized 1005 patients to a lower hemglobin threshold (7 g/dL) or a higher hemoglobin threshold (9 g/dL). 
• Overall, there was no difference in 90-day mortality between groups.
• Patients randomized to the lower threshold received significantly fewer units without any increase in ischemic or adverse events.
• Take Home Point: A hemoglogin threshold of 7 g/dL for blood transfusion appears effective for most patients with septic shock.

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The ARISE Trial

Early, aggressive resuscitation and attention to detail are essential element of managing critically ill patients.  This past week the ARISE trial was published - a 2nd large, randomized control study to examine the benefit of protocolized vs. usual care in patients with severe sepsis and septic shock. 

What were the main findings?  After enrolling 1,600 patients who presented to the ED in severe sepsis or septic shock:

• They found no difference in mortality between the control (usual care) and treatment arm (early goal-directed therapy)
• Mortality was 18.6% vs. 18.8% at 90 days
• No evidence that continuous ScVO2, Hgb target > 10 mg/dL (check out the TRISS trial), or use of inotropes with a normal cardiac index improved mortality

Bottom Line:  Resuscitation goals for the patient with septic shock should include:

• Early antibiotics (source control)
• Adequate volume resuscitation (preferably balanced, crystalloid solution)
• End-organ perfusion (lactate normalization)

Additional therapeutic goals should be made on a patient by patient basis.  Reassess your patient frequently, pay attention to the details, and you will improve your patient’s mortality.

Suggested Reading

1. The ARISE Investigators and the ANZICS Clinical Trials Group.  Goal-Directed Resuscitation for Patients with Early Septic Shock. N Engl J Med. 2014. [PubMed Link]
2. Wessex ICS: The Bottom Line Review

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