affect of shocked or paralyzed hemidiaphragm on Swan-Ganz readings

[deluded]

i was lucky enough to be accepted into a critical care internship following graduation two years ago and then hired to work in a unit that recovers two to three open heart cases each day. over the last year i've cared for a handful of patients who returned from surgery with shocked or paralyzed hemidiaphragms; these always seem to evolve into cases with multiple additional complications. this last week i had the same patient every day; the case involves a right-side elevated diaphragm to the mid-cardiac outline on cxr with the swan tip in that same side, of course. it is a very complicated case that has motivated me to study/research for several hours each night after my shift. the md continued to use the pad as a principle indication of fluid volume status, and with my lack of experience i kept my misgivings to myself (this is a doctor who i respect highly and who i generally am not afraid to prompt for bedside education, but with the delicate nature of the case i didn't feel comfortable taxing that relationship). i can not find information on how this particular pulmonary issue affects the reliability of the swan-ganz pressures or if the readings are useful at all. i can theorize on what the increased density of the pulmonary vasculature/tissue does to the pressures, but i'd like to hear what better educated/experienced nurses have seen or done in this not-too-infrequent set of circumstances. direction to any reference materials addressing this would be greatly appreciated, too.

thank you for your help, v

[Biffbradford]

Unless theories have changed in the 18 months since I last worked in CVICU, we never worried about a paralyzed diaphram affecting swan readings. It certainly was a problem when weaning from the vent. however.

[deluded]

thank you for the reply,

my thinking is that confining the lung to half of its normal volume must change the flow of blood through it (and so the pressures)... not to mention that with the vq mismatch there is sure to be secondary chemical effects on the pulmonary vascularity of that side, too.

[aCRNAhopeful]

thank you for the reply,

my thinking is that confining the lung to half of its normal volume must change the flow of blood through it (and so the pressures)... not to mention that with the vq mismatch there is sure to be secondary chemical effects on the pulmonary vascularity of that side, too.

Certainly a good thought. I would still think that the effects on pressure would be negligible since not all pulmonary vasculature is perfused at once. Even if the lung is half its normal volume I'd still be inclined to think that there would be some "reserve" of non perfused vasculature that blood could flow through.

[TakeBack]

Diaphragmatic paralysis/paresis causes significant basilar atelectasis and lobar collapse. This increases the amount of non-ventilated lung. Compression of these segments can increase right heart afterload and thus give mild pulmonary hypertension, though the effects in unilateral diaphragmatic paralysis are probably minimal. If you are trending PADs it's probably reliable.

[RN-ing, BSN, MSN, NP]

Are you able to check a CVP? If so, does it support your PAD readings?