Respiratory
Increasing ventilatory requirements that risk barotrauma
P to F ratio: how much PaO2 you get for an amount of FiO2 delivered
Oxygen Index = (Mean Airway Pressure * FiO2 * 100) / PaO2
OI 4-8: Mild lung injury
OI 8-16: Moderate
OI greater than16: Severe, with around 40% mortality
OI greater than 25: Strongly consider ECMO
OI greater than 40: ECMO
Consider heart function and adjunct therapies like prone positioning and oscillator or other ventilator settings.
In pulmonary hypertension, a trial of NO may be used.
Considerations:
Circuit availability
ECMO capabilities
Transport capabilities
If I am a trainee in the middle of the night, what do I need to know for a respiratory ECMO consult?
OI
Echo
To evaluate hemodynamics, what the underlying heart function is.
If heart function is only affected due to high ventilator requirements, different story.
RV dilation: may trial NO to see if it reduces pressures.
LV dilation: more concerning, maybe VV ECMO would be insufficient, even if first choice for respiratory failure ECMO.
CXR
Primarily looking for: adequate ventilation on both lung fields, pneumothorax.
If there’s a collapsed segment, bronchoscopy may be useful getting rid of mucus plugs.
Pressors
To decide how advanced their disease process is.
Underlying disease
Pneumonia, aspiration, sepsis?
Location of central access
Where am I going to cannulate?
Head ultrasound?
If there is time, it may be useful for prognostic value, especially if young enough. Hemorrhage grade 2 or lower, not a contraindication, ok to go on ECMO. If sutures are already
Grade 3 intracerebral hemorrhage would not be a great candidate for ECMO
Other contraindications:
Active bleeding would be a consideration.
Historically, long ECMO runs (longer than a week or two) would be strong consideration against ECMO. Now, it is considered higher risk but still performed if it is a reasonable option. Lungs may take longer to recover, but we are seeing success in long remodeling for respiratory ECMO.
Extreme prematurity, or prematurity under 30 weeks.
Patient under 1,200 grams.
Adequate size cannula not available.
Previous ECMO at that site may make it challenging.
Good time to set up arterial lines or other procedures before heparinization (chest tubes, Foleys, etc).
Sepsis
ECMO does a fantastic job for oxygenation and ventilation (functions of the lung); however, it is not great at maintaining vascular resistance.
In patients with low pressures, especially low diastolic, you may require flows over 150 per kilo, larger cannulas (including considering central cannulation), and consideration of VA ECMO.
More hesitation to go on ECMO for sepsis, attempt other therapies. Although you can replace the pump function, it is hard to replace tone.
eCPR
Adjunct to bystander CPR.
It’s an evolving field.
Great neurologic outcomes in centers with established experience.
Michigan does cardiac eCPR for known patients after cardiac surgery, hypothermic patients put in VA during rewarming.
Pre-hospital is too challenging at this time, although adult pre-hospital is more advanced.
CDH
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ECMO Modalities:
VV is more than adequate for respiratory failure.
VA in left sided heart disfunction, poor cardiac function with high dose pressors.
VA is an alternative for inadequate VV.
ELSO neurologic injury:
Stroke, death, seizures, brain death.
Highest rate in neonates, who have the highest rate of VA use.
Rate of neurologic injury decreases with age.
Risk of neuro injury 21% with VA and 16% with VV.
Risk of stroke is 5.1% for VA and 3.5% for VV.
Cannulation strategies:
Neonate with respiratory failure and adequate cardiac function:
VV modality
Right neck approach
Cut down open technique, ligate the internal jugular vein, and place an OriGen cannula.
Adolescent with respiratory failure and adequate cardiac function:
VV modality
Avalon cannula under fluoroscopy AND echocardiography guidance.
Can do bedside but prefer OR due to availability of rescue resources.
Use ultrasound to access internal jugular vein, use a micropuncture needle to place a straight wire and then exchange for a longer wire from the Avalon kit. If unable to advance to IVC, place KMP catheter with a bend in the end to thread it. The stiffest possible wire will prevent it from flipping out as advancing the Avalon. Dilate over the wire and place the catheter.
As soon as catheter in IVC, heparinize at 100 per kilo.
In position, use contrast through the reinfusion limb to place in RA above the diaphragm, above the IVC/RA junction, so that even when edema pulls catheter up it remains in position.
On fluoroscopy, the middle hepatic vein and IVC overlay; echo may help delineate this better……
