Grand Rounds Recap 2.21.18

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Morbidity and mortality conference WITH DR. Lagasse

CASE 1:  Carbon Monoxide Poisoning

Background:

  • Carbon Monoxide poisoning responsible for >50,000 ED visits annually in the US
  • It is the #1 cause of poisoning death in the US
  • Physiology review
    • CO is a colorless, odorless, tasteless gas
    • It has 200 times greater binding affinity to hemoglobin than oxygen
    • Displacement of O2 leads to tissue hypoxia

Symptoms and sequelae:

  • Symptoms:  Often non-specific.  Can include headache, dizziness, weakness, upset stomach, vomiting, chest pain, confusion, muscle aches
  • Sequelae:  There are many, but the major systems affected are those with high metabolic/oxygen demands.  Can both persistent or delayed.
    • Neuro-psychiatric
      • Memory loss/difficulty (Primarily short term)
      • Ataxia
      • Vestibular disturbances
      • Dementia
      • Psychosis
    • Cardiac
      • Global LV dysfunction
      • Regional wall motion abnormalities can also be seen
        • This is more common in elderly patients with underlying CAD
        • Poorly perfused regions more greatly affected by global hypoxia in CO poisoning (Essentially like a failed stress test)
    • General
      • Patients with history of CO poisoning have been found to have reduced life expectancy.  Reason is unclear, but may be as a result of myocardial damage and predisposition to arrhythmia

Assessment:

  • Carboxyhemoglobin level
    • Value is a function of both concentration and time of exposure
    • Level in ED may not correlate with amount of exposure
    • Interpretation may change with smoking history
      • Non-smoker:  >3% abnormal
      • Smoker:  >10% abdmormal

Management

  • Remove from area of exposure
  • High oxygen therapy is mainstay of treatment
    • Half life of CO on room air:  6 hours
    • Half life of CO on non-rebreather mask:  90 minutes
    • Half life of CO in hyperbaric chamber:  30 minutes
  • Hyperbaric therapy (Chamber with 100% O2 and 1.4 atm absolute pressure)
    • Shown to more rapidly displace CO from hemoglobin/tissue
    • Actual utility in clinical management of CO poisoning is still debated
    • Review of current literature:
      • Weaver et al, NEJM 2002
        • Study evaluated the neuro-psychologic effects in patients following either hyperbaric O2 vs. O2 at normal atmospheric pressure
        • Found that patients who received hyperbaric oxygen had better neuropsychologic testing outcomes at 6 and 12 months
      • 2011 Cochrane review
        • Analyzed existing literature around hyperbaric oxygen for CO poisoning
        • Conclusion:  Not enough data to support routine use of hyperbarics
    • Current guidelines
      • Hyperbaric medical society recommends hyperbaric use in "Severe Poisoning," defined as one of the following:
        • Carboxyhemoglobin > 25%
        • Age > 36
        • AMS
        • Cardiac dysfunction
        • Severe acidosis
      • ACEP
        • Does not routinely recommend use of hyperbaric oxygen
        • Non Rebreather mask remains mainstay of treatment
    • General recommendation
      • Non rebreather is probably sufficient for most cases
      • Consider hyperbaric chamber/transfer for hyperbarics if:
        • Pregnant
        • Significant neurologic sequelae
      • Consider discharge in the following patients
        • Has received high flow oxygen on non-rebreather mask for 4-6 hours
        • No evidence of sequelae
        • The patient's social situation is appropriate (Has alternative place to stay / CO source has been eliminate)

Arrest from Carbon Monoxide Poisoning

  • Prognosis is dismal
  • Consider other poisoning (eg. cyanide in house fires)

CASE 2:  Medication Induced Hyperkalemia

Background:

  • Drug induced hyperkalemia is common, and is responsible for many the cases of hyperkalemia in hospitalized patients
  • Mortality of hyperkalemia in hospitalized patients is 1 per 1,000 patients

High Risk Patients

  • Moderate-Severe chronic renal insufficiency
  • History of HIV/AIDS
  • History of Rheumatologic disease
  • Hypo-aldosteronism
  • Elderly/polypharmacy

High Risk Medications

  • Beta Blockers:  Decrease activity of Na+/K+-ATPase pump and renin release
  • Digoxin:  Inhibition of Na+/K+-ATPase pump activity
  • NSAIDS:  Decrease of prostaglandin-mediated renin release, renal blood flow and glomerular filtration rate
  • Heparin:  Inhibits aldosterone synthesis
  • Bactrim:  Blockade of luminal sodium channels causing less of a gradient for potassium
  • ACE Inhibitors:  Inhibits aldosterone production leading to decreased renal potassium excretion

ACE Inhibitor and Bactrim Combination

  • 7 Fold increase in risk of hospitalization
  • Common combination in elderly patients with UTI
  • Increased risk of death in same population, likely due to hyper K+ and subsequent arrhythmia

CASE 3:  Spontaneous Heterotopic Pregnancy

Background

  • Heterotopic pregnancy is a multiple pregnancy with one embryo implanted in the uterus and another at an ectopic site
  • "Spontaneous" refers to this event occurring without fertility treatments or medications to induce ovulation
  • Rare, occurring in 1 in 30,000 cases
  • Usually diagnosed before 11 weeks gestation

Risk factors

  • Same as ectopic pregnancy

CASE 4:  Evaluation of the Suicidal Patient

Background:

  • Studies have shown that 6-10% of ED patients have had or currently have thoughts of suicide
  • JCAHO has mandated that all patients with psychiatric symptoms should be screened for suicidality/homicidality
  • Our ED's current practice is universal screening

Risk Factors for suicide:

  • Male sex
  • Older age (>44)
  • Sexual orientation
  • History of self harm
  • No history of outpatient psychiatric care
  • Education (High school or less)
  • Alcohol or substance abuse disorders
  • Specific occupations
    • Physician
    • Lawyer
    • Veteranarian

High risk time periods:

  • Interpersonal stress
  • Loss of a family member
  • Financial or legal difficulties
  • Physical illness

Protective factors:

  • Well developed social support network
  • Strong reasons for living
  • Responsibility for young children
  • Religiosity
  • Extroversion and optimism
  • Effective coping and problem solving

Approach in the ED:

  • Assess decision making capacity
  • Information gathering
    • Take history, assess risk and protective factors
    • Obtain collateral information from family/friends/other
    • Assess their access to lethal means
      • Firearms
      • Medications
      • Chemicals, etc
  • Use decision support tool / Screening tool
  • Disposition
    • Low risk patient:  Consider discharging if the following are met:
      • You can assure outpatient follow up
      • You are able to explain and distribute information on warning signs, crisis line
      • Involve the patient's family
      • Document risk level and rationale
      • Document a plan to reduce risk (Safe place to stay, reduce access to firearms, etc)
    • Moderate to high risk:  Transfer to psychiatric emergency services or admit for psychiatric evaluation

AIr care grand rounds organized by Dr. Dang and Dr. Renne

Balloon Pump Transfers:

Basic principles of balloon pump

  • Designed to augment cardiac output and diastolic pressure
    • Inflates during diastole => Increasing aortic pressure during diastole, leading to increased coronary perfusion
    • Deflates during systole =>  Creates vacuum in aorta helping to augment cardiac output (CO)
  • Positioning
    • Balloon should be situated between the left subclavian artery and the renal arteries within the aorta
    • Balloon is filled with helium
      • Less likely to form air embolus if balloon ruptures (Though still possible)
      • Better laminar flow
  • Contraindications
    • Aortic regurgitation
    • Severe peripheral vascular disease

Assessing the balloon pump patient

  • Review patients X-Ray if possible to assess for correct placement
  • Check pulses to make sure balloon is not occluding major artery
    • Best to check left radial pulse
    • Place pulse ox on left hand
  • Should have foley.  Monitor UOP to make sure not obstructing renal arteries

Transferring the balloon pump patient

  • Bring the pump in to the patient's bedside to make sure all equipment is compatible/present
  • Copy the hospital's settings for the balloon pump onto out machine
  • Best to keep on AUTO setting
  • Set augmentation alarm to 10mmHg below the augmented pressure
  • Transfer the balloon pump after organizing drips (Last thing along with vent)
    • Attach ECG cords
    • Attach pressure monitor (Fiber optic)
    • Transfer helium balloon
  • Keep lines together
  • Best to dedicate someone to moving the pump
  • Fasten in helicopter with holder (pilot will help install)
  • Have machine facing seats and not rear facing

Monitoring and troubleshooting

  • Power
    • Replacement batteries in the backpack
    • Plug in during flight
    • Batteries last 45 minutes each
  • Waveform
    • Waveform will be present on the screen
    • Will essentially look like A-line tracing when balloon not inflating
    • Will have an additional bulge upward when balloon inflated
    • Balloon can be set to inflate 1:1, 1:2, or 1:3
  • Helium
    • Helium level shown on the screen (Refilled by maintenance)
    • Waveform should look like a chair
    • Most common failure is a purge failure, which means helium us unable to empty from the balloon.  Usually caused from a kinked line
    • Solved by laying the patient flat
  • Balloon
    • Rust coloring in line suggests balloon leak
    • Turn off pump to avoid air embolus
    • Will need to re-inflate every 4-5 minutes to prevent clot
  • Timing
    • Common errors
      • Early inflation:  DANGEROUS.  Means it's inflating against an open aortic valve
      • Late inflation:  Fine, but means it's not optimized
      • Late deflation:  DANGEROUS.  Heart pumping against inflated balloon

Cardiac Arrest with Balloon Pump:

  • If patient is pulseless, balloon will default to pressure mode
  • IF PEA, balloon will still trigger.  Will need to switch it to pressure mode
  • If arrhythmia or fast heart rate => Switch to pressure mode
  • Can perform CPR in pressure mode

 

Impella Transfers

Device:

  • Different sizes (2.5 and 5), with 2.5 and 5L of CO augmentation respectively
  • Percutaneous line, usually through femoral artery (axillary also possible)
  • Parts
    • Pigtail catheter helps pump sit in ventricle
    • Pump portion in ventricle
    • Marking should be at level of valve
    • Outflow port in aorta
    • Lubricant / D5 flow at outflow port
    • Catheter through aorta out of groin.  Connects to control module
  • Control module is portable.  Weighs roughly 25 pounds

Transfer

  • Drive line attached to monitoring unit
  • Will also require several drips
    • D5 lubricant
    • Heparin
    • MUST BE MAINTAINED
  • Need to ensure that catheter protection sheath (Swandom) is secured

Monitoring

  • Monitor should show two lines
    • Aortic wave form:  Should mimic A-Line, should not look ventricular
    • Pump/Power wave form:  Should also look pulsatile as ventricle assists pump
  • Suction alarm
    • Common causes
      • May be due to placement
      • Low preload
      • RH failure
    • Solutions
      • Drop power
      • Give fluid
      • Keep CVP > 10 if monitored

Cardiac arrest with Impella

  • If CPR, turn down power/flow

EKOS Catheter

Device:

  • Dual purpose catheter
    • High frequency, low energy US helps break up clot
    • Catheter allows localized delivery of thrombolytics
  • Uses
    • Sub-Massive PE
    • Peripheral DVT

Transfer:

  • Control box does not transfer with patient
    • Curl up wires
    • Place in glove to keep dry
  • Things to consider
    • TPA must be maintained on pump
    • Coolant must be maintained on pump as well
    • Will need to be on heparin
    • The catheter itself is difficult to suture in because it can occlude TPA
      • Be careful when moving the patient

Left Ventricular Assist Device (LVAD)

Types of VADs

  • Axial flow pump
    • Heartmate II (Most common at UC)
  • Centrifugal flow pump
    • Heartware
    • Heartmate III

Basic mechanics

  • Inflow catheter from ventricle
  • Pump sucks blood from ventricle
  • Outflow catheter anastomosed into aorta
  • Right heart VADs also exist from RV to PA

Monitoring

  • LVAD creates continuous flow
    • BP needs to be obtained by doppler
    • Pulse ox not reliable for pulse
  • EKG should not be greatly affected by VAD

Common complications

  • Suction event
    • Give bolus
    • Decrease speed
    • SHOULD AUTOCORRECT
  • Thrombus
    • Spike in power
    • Decreased flow
  • Loss of flow
    • Low power / Loss of power
      • Batteries last 12 hours
      • Should have a line from each battery going into controller module
    • Drive line
      • Check and make sure connected

Cardiac arrest with VAD

  • Check device
    • Drive line plugged in
    • Batteries attached
    • Assess power, speed for signs of suction or thrombus
    • Depending on local protocol, may begin CPR, follow ACLS
      • Know that CPR has theoretical risk of dislodging VAD

Determining transfer location

  • Ideally transfer to medical home (Implanting facility)
    • Will have LVAD monitor/docking station/extra batteries
  • If unstable, closest ED