VV ecmo

[coffeebythelake]

Would a conscious patient who is put on essentially 100% VV ecmo have any drive to breathe?

Perhaps more of a hypothetical question. I would think no?

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[bigtuna]

Short answer is yes they do.
There really isnt such a thing as “100% vv ecmo”. The post oxygenator blood may have a very high oxygen content but it is still mixing with some normal venous blood.

A lot of times patients that are on vv ecmo for an ards type picture have very small tidAl volumes to prevent ventilator induced lung injury. Sometimes this results in an incredible drive to breathe. Sometimes it seems to respond to increasing sweep (decreasing pCO2) and sometimes not.

 

[dchz]

Short answer: yes. The respiratory drive is more dependent on pH.

Long answer: it would depend on the pts lungs, sweep speed on VV ecmo, and other physiologic processes that might affect pH. The drive will be there when the pH is low.

Also they don't have to be conscious, theoretically.

 

[vector2]

Your question presupposes that the respiratory drive only follows pH, but in actuality each person has an intrinsic respiratory drive (like a junctional escape rhythm, ventilatory neurons are not capable of going to zero tonic activity no matter the pH) that is subsequently adaptive based on peripheral mechanoreceptors and peripheral/central chemoreceptors. For instance, a healthy person walking around on room air with doesnt have a cyclic slowing of the respiratory rate until acidemia builds and then a quickening to compensate for it. Rather, they just breathe at an intrinsic rate of ~12 and then slightly slow or speed up depending on various inputs.

Similarly, I would expect that the body on hypothetical 100% VV ecmo with a normal pH would go about business as usual with a tonic RR that is close to baseline.

 

[T-burglar]

Irritant receptors in the lung probably cause dyspnea even with a normal blood has if that theory is correct

 

[Modanq]

Yes, think of awake patients on VV ECMO as a bridge pre-lung transplant.

Pointers: ICU + CV Anesthesiologists have scope of practice to cannulate VV ECMO.
At our institution we cannulate and do this routinely.



Also: From this month Sept 2019 Anesthesiology

Venovenous Extracorporeal Membrane Oxygenation for Rigid Bronchoscopy and Carinal Tumor Resection in Decompensating Patients

Patients with obstructive tracheal masses may have long-standing dyspnea before presenting with respiratory distress. Indeed, a mass may be missed if dyspnea is attributed to other pathophysiological mechanisms. We present a computed tomography scan revealing a 2.4 × 2.1 cm mass causing near...

anesthesiology.pubs.asahq.org

 

[psychbender]

Yes, and it's an interesting exercise titrating sweep on an awake, extubated pt on VV (or VA) ECMO.

 

[coffeebythelake]

Yes, think of awake patients on VV ECMO as a bridge pre-lung transplant.

Pointers: ICU + CV Anesthesiologists have scope of practice to cannulate VV ECMO.
At our institution we cannulate and do this routinely.



Also: From this month Sept 2019 Anesthesiology

Venovenous Extracorporeal Membrane Oxygenation for Rigid Bronchoscopy and Carinal Tumor Resection in Decompensating Patients

Patients with obstructive tracheal masses may have long-standing dyspnea before presenting with respiratory distress. Indeed, a mass may be missed if dyspnea is attributed to other pathophysiological mechanisms. We present a computed tomography scan revealing a 2.4 × 2.1 cm mass causing near...

anesthesiology.pubs.asahq.org

This was actually the kind of scenario that made me ask this question. We dont do this type of thing at my institution.

 

[abolt18]

This was actually the kind of scenario that made me ask this question. We dont do this type of thing at my institution.

We don't either, but then again most of our patients on VV ECMO have such severe ARDS we've got them on 100% O2 on the vent and on ECMO just to maintain a PaO2 in the 50s.