shock states

[bell412]

why is uptake quicker in low CO states? I think I understoood this concept awhile ago but all the other s..t I've learned has moved it out of my brain.

 

[UTSouthwestern]

why is uptake quicker in low CO states? I think I understoood this concept awhile ago but all the other s..t I've learned has moved it out of my brain.

With low output states, less anesthetic is taken up by the blood, and alveolar concentration increases more rapidly. Highly soluble agents (Halothane, Iso, etc.) are most affected. With a poorly soluble agent, the rate of F alveolar/F inhaled increase is rapid regardless of the cardiac output and thus is not as affected by a decrease in cardiac output. With highly soluble agents, a potentially dangerous positive feedback exists in that anesthetic-induced cardiac depression decreases uptake, increases alveolar concentration, and further depresses cardiac output.

The same principle applies to right to left shuntinng.

 

[powermd]

With low output states, less anesthetic is taken up by the blood, and alveolar concentration increases more rapidly. Highly soluble agents (Halothane, Iso, etc.) are most affected. With a poorly soluble agent, the rate of F alveolar/F inhaled increase is rapid regardless of the cardiac output and thus is not as affected by a decrease in cardiac output. With highly soluble agents, a potentially dangerous positive feedback exists in that anesthetic-induced cardiac depression decreases uptake, increases alveolar concentration, and further depresses cardiac output.

The same principle applies to right to left shuntinng.

Can you give some examples of real-life situations in which this principle is clinically relevant?

 

[UTSouthwestern]

Can you give some examples of real-life situations in which this principle is clinically relevant?

Uncompensated heart failure, shock (vasogenic, cardiogenic, hemorrhagic, etc.), cardiomyopathies, severe valvular pathology, arrythmias decreasing effective ejection, intrapulmonary shunts, intracardiac shunts with right sided pressures > left sided pressures, Eisenmenger or severe pulmonary hypertension, severe volume depletion, the list goes on and on.

 

[powermd]

So what do you do in these cases to avoid the previously mentioned positive-feedback loop? Do you avoid inhaled anesthetics all together? Do you favor a less soluble gas?

 

[jetproppilot]

So what do you do in these cases to avoid the previously mentioned positive-feedback loop? Do you avoid inhaled anesthetics all together? Do you favor a less soluble gas?

Not an issue today in the des sevo era.