Thsi ipenatt ash a emxho.ounrpat ivtyiHlrtpolaeenn is nto gnohue to cametosepn fro eht veollra recedsea ni ngul casuefr .aear
xr-ay ecsnsoodrrp ot a etiosnn oxtmounaerph = neniimmt ytrrripaoes iurealf fi .eettandur Rhitg lnug is yufll dcaeloslp, irsngineca otcni-rachtiar sse,eprur maiigrpn 2O agecxhne u(ed to mssa ftfcee rtwado etlf g,unl dan cldlseopa irhtg o),ne ecehn nuglumiccaat O2C ni( ood,b)l iiudcgnn ptyarreorsi assi.icod
exact picture from the exam explained. :)
I thought of this as a giant physiologic shunt (ie, due to the pneumothorax there is no ventilation to an entire lung, as a consequence you retain CO2) - not sure if this is the actual mechanism but it helped me get this question right
hopefully this helps!
Keycompany gave the quick, simple explanation.
but from a less-clinical perspective: If anyone has ever been "Lit-up" on the football field, or just generally ever had the "wind-knocked out" of them, you know that your breathing for the next 5 minutes is very shallow because it just hurts to breath too deep.
This girl broke a rib so likely can't breath very deep, so even though she is breathing rapidly the CO2 is likely remaining in her lungs and causing a respiratory acidosis.
Also, here is why the other answers don't make sense:
Amyloidosis & carcinoid - long term problems not related to a broken rib and acute presentation Empyema- "collection of pus" wouldn't form this soon and if it did the percussion would not reveal increased tympany. Pulmonary edema- percussion would not reveal increased tympany. PE- Could cause similar symptoms but percussion would not reveal increased tympany, and the x-ray and history of trauma tells you that this is definitely a pneumothorax.