(NOTE: I have not answered the question here, simply listed all the CVS effects of all the volatiles)
· Table
· Details of that table
· Guedel’s stage 2
|
|
Halothane |
Isoflurane |
Enflurane |
Desflurane |
Sevoflurane |
|
Contractility |
↓↓↓(A) |
↓ |
↓↓ |
- |
↓ |
|
HR (A) |
↓↓ |
↑↑ |
↑ |
↑ |
- |
|
SVR |
-/↓ |
↓↓ |
↓ |
↓↓ |
↓ |
|
mAP |
↓↓ |
↓↓ |
↓↓ |
↓↓ |
↓ |
|
Cerebral blood flow(B) |
↑↑↑ |
↑ |
↑ |
↑ |
↑ |
|
Splanchnic blood flow |
↓↓↓ (risk T1HH) |
|
↓ |
|
|
|
Sensitisation to catecholamines |
↑↑↑ |
|
↑ |
|
|
|
SNS stimulation (C) |
|
|
|
Y |
|
|
Anaesthetic preconditioning (D) |
Y |
Y |
Y |
Y |
Y |
|
Prolonged QTc (insignificant) |
|
Y |
Y |
|
Y |
|
(A)Heart rate:
|
· Halothane -> ↑PSNS tone and direct depressant effect · Others: ↓mAP -> reflex ↑HR (preserved baroreceptor reflex) |
|
(B)Cerebral blood flow: |
· <1MAC: ↓CBF (↓CMRO2 predominates) · >1MAC: ↑CBF (vasodilatation predominates) · Halothane: ↑ICP if MAC >0.6 · Desflurane: least of all volatiles |
|
(C) SNS stimulation |
· Rapid ↑[desflurane] -> SNS stimulation -> ↑HR/contractility/SVR · Especially >1.5MAC · ? Airway irritation ? Systemic effect (since occurs on CP bypass) |
|
(D) Anaesthetic preconditioning |
· Activation of mitochondrial and sarcolemmal ATP-sensitive K+ channels -> hyperpolarization · Occurs at MAC >0.25 · Mimics ischaemic preconditioning |
· ↑SNS output -> ↑HR, ↑cardiac output
· (Also irregular respiration, breath holding, laryngospasm etc.)