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RESPIRATORY PHYSIOLOGY

Pulmonary Function Testing—cont'd

Mguimol «pBu!oc>    Spitomeief ot

(WyoIuiih* cwvr    pneumojachoyaph

breaMng 60% He    to tecofd flow and

and 20% O,    V iw V y-okone

Closjng volumr Ctoung capacity

Airways iti the Iowcr lung zoncs closeat Iow lung yplumes and only those abeoli ar top ol lungs conlinue to empty. ffw.mie ronrnntratmn of N_? In abeoli of upprr ronr*> is big) ter. tln- slope u! ihp mrvo abruptjy incteases (plute lVl. Pha^e IV' bcgins at larger lung yulumrs in indbiduaU willi men minor degrees of airway obslruclioo increasmg bolli CV and CC

Vol<%VC)    Voli%VC|

$ Dunng a maxunal esplratory maneuwr, resisrance to aeflow b nor maiły due to turtwlcnce and coflvettive $ accełeratinn. Hrr-.irhing I In, wh*rh is less deiise llian air. luwcrs resisłance and increases flow at .di bul thr S townJ yolumcs. In smali airway disease, resistancc to laniinar flow makt-s up largrr portion of total tesistancc £| and airflow s telatheły Independent of gasdenaly. Inueasc m exfxrj(ory fiówat 50% of VC wbili* bre.ithing f, He-Oj iJiVnia» sol will ho less, and yufome al whirfi flows whilc broalhlng Me-Oj andwłiile htoaihing airare « identiral (V iso Vi will be higher iii (Jiirients with smali airway disease tlun in norin.d mdwiduals

Ga* enchange Partia! pressute ot O, In arteria! blood	ro.	Arteria) bćood i*, collectcd ar-aetobioilb In	Normal values 60 to 100 mm Hg brcalbing ronm air at sca k-vcl; falls slightfy with ag<	Abnormalities 1 lyponcmia indicarlye Ol yentiLition/perfiision abnornulities. sliunK diffuSłon detect. abeoiar bypneentilalioo
Partial pressure of CO, in arteria! Uuod		hrparinired syn/łgo	36 to 44 mm Hr	P<«.. prnporliorul to ineiabołic rale tCO.. productioni and inveneły relalcil lo volume ot' aKeotir ventilation
Ai te? ml titoad pH	pH		7.35 lo 7.45 pH	Acidosts (pH <7.35) Keswatory linadesjuale abeolar viMUilatk>nl Metabolic (gam of add and/Oe loss or basel Alkalosts (pH >7.43) Respiratory <excessive abeolar yentiblionl Metabolit. (gam of lwic or loss ot addl
AlveOłai-.irtPJVil Oj drffcrcncc-	i A-aOa, t A^Po,		c 10 mm Hg breathing	Ptiiiuiily reileciN nK>m,itching oł ventilation and perfusinn amf/or shunts; may abo bc atrected by diffusioii defccts
Ui*ad space/tkiol y-oiiime talio	Vo/Vt	Derwmined finm .eterial and fnlKcd ©tpiredPco,	<0.3	flcvated ratio inrikaleswasteli vent2.1tinn; i.*.*., tbat tolwne of gatwbieb dnes not lakę pait in gas t*xchanRc
Shunt fraccio n	Qt/Qr	Oelermincd from Po, after a period of breathing 100% O,	<5%	Elev.ition indicalcs mtreasod amount ot mixed vm<Kis blood entering systemie ctrculatioo wilhnut i oming into cnntacl with aboolar ait. eitlier beeause ot sbunting of blood past lungs to left Side ol he.irt or perńrsion of repom of lung wh*h are not vent2at«l

IW

Figurę 5.28 Tests oe Pulmonary Function—cont'd_

This figurę illusiraies pulmonary function tests and comparalivt? values for normal lungs and diseased lungs (obstructive or restriciive disease).

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