tet spells and knee-chest



F

Faisal Vali

Guest
[this may be a double post - i apologize, i'm still figuring out my news reader]

Can someone please explain to me why the knee-chest position helps when dealing with tet spells in
cyanotic tetralogy of fallot patients?

What I've been told is that it tends to increase systemic resistance - thus decreasing the R->L
septal shunt, and encouraging pulmonary flow.

I guess I don't see the physiology behind the knee-chest position increasing the systemic
resistance?

(Does it increase venous return? Is it some form of reflex that triggers vasoconstriction? Is it
increasing intrathoracic pressure (but that would decrease venous return) and thus increasing
arterial tone similar to the mech behing valsalva?)

thanks in advance! regards, Faisal Vali