September, 1960 P H Y S I O T H E R A P Y Pulmonary Function Tests Page 5 B y D r . L . D . E R A S M U S , M .B ., B .C h . ( R a n d ) , M .D . ( P r e to r ia ). M e m b e r o f th e F a c u l t y o f M e d ic in e , P r e to r ia U n iv e r s ity A L e c tu r e g iv e n to D e le g a te s a n d M e m b e r s o f th e S o u th A fr ic a n S o c ie ty o f P h y s io th e r a p y o n the f i r s t d a y o f th e “ C h e st C o u rse , w hich w a s h e ld a t th e P r e to r ia H o s p ita l P h y s io th e r a p y S c h o o l o n M a y 2 1 th a n d 2 8 th , i9 6 0 . PU L M O N A R Y f u n c tio n te s ts a r e o f c o n s id e ra b le v a lu e is a s se s s in g t h e p h y s io lo g ic a l s t a te o f th e lu n g s a n d c a n b e u se d in m a n y in s ta n c e s a s a d ia g n o s tic to o l. F r e ­ q u e n tly , h o w e v e r, it is u se d to a s se s s t h e d e g re e o f d is a b ility a n d in o th e r in s ta n c e s to a s se s s p ro g re s s m a d e w ith tr e a tm e n t. Specific d ia g n o s tic p r o b le m s in c lu d e th e in v e s tig a tio n o f cases o f p o ly c y th a e m ia , o b e s ity a n d th e h y p o v e n tila tio n sy n d ro m e . T h e y a r e s o m e tim e s u se d a ls o t o as se s s th e efficiency o f t h e r e s p ir a to r y m u sc le s. Tt is c o n v e n ie n t to c o n s id e r p u lm o n a r y f u n c tio n te s ts u n d e r t h e h e a d in g s o f v e n tila to ry a n d r e s p ir a to r y f u n c tio n . Ventilatory Function. T h e b a s ic a p p a r a t u s r e q u ire d is a s p ir o m e te r w ith a r e c o r d in g d r u m a n d a m e th o d f o r a s se s sin g re s id u a l v o lu m e b y a g a s m ix in g te c h n iq u e . B e fo re p r o c e e d in g a n d f u r th e r , h o w e v e r, I w o u ld lik e to r e m in d th e a u d ie n c e o f th e b a sic d iv isio n s o f lu n g v o lu m e a c c o r d in g to th e so -c a lle d “ N e w ’' T e rm in o lo g y o f P a p p e n h e im e r , in tro d u c e d in 1950. S im p le s p ir o m e tr ic m e a s u re m e n ts c a n giv e c o n s id e ra b le in f o rm a tio n in a m a t t e r o f m in u te s . T h u s a ll th e d iv is io n s o f to ta l lu n g c a p a c ity e x c e p t th e re sid u a l v o l u m e c a n b e d e te rm in e d b u t th e re s id u a l v o lu m e h a s to b e in d ire c tly d e te rm in e d b y a g a s m ix in g te c h n iq u e . T O T A L lu n g c a p a c ity V ita l c a p a c ity I n s p i r a t o r y re se rv e I n s p i r a t o r y c a p a c ity T id a l v o lu m e E x p ir a t o r y R e s e r v e v o lu m e F u n c tio n a l R e s id u a l C a p a c ity R e s id u a l v o lu m e Vital Capacity. -D e te rm in a tio n o f th e v ita l c a p a c ity is f re q u e n tly v a lu a b le b u t h a s a lim ite d a p p lic a tio n . C o n s id e r a b ly m o r e v a lu e is i n tr o d u c e d i f a tim e f a c t o r is a ls o c o n s id e re d . F o r e x a m p le t h e v ita l c a p a c ity in e m p y s e m a a n d b r o n c h ia l s p a s m m a y b e n o r m a l b u t if th e 2 -se c o n d v ita l c a p a c ity is m e a s u re d , a c o n s id e ra b le r e d u c tio n is u s u a lly f o u n d . D e te r m i n a t i o n o f th e tim e d v ita l c a p a c ity a f te r th e re n e w a l o f s p a s m u s in g a b r o n c h o - d ila to r d r u g is a ls o v a lu a b le in d is tin g u is h in g b r o n c h ia l s p a s m f r o m p e r m a n e n t o r g a n ic c h a n g e . In g e n e ra l it c a n b e sa id t h a t r e s tric tiv e p u l m o n a r y le s io n s ' 4 THE BIRTCHER MEGASON VI ULTRASONIC UNIT To t he m o re t h a n 20,000 p h y s ic ia n s now u s in g u l t r a ­ sonic th e r a p y in th e t r e a t m e n t o f a h o s t of a c u te a n d c h ro n ic c o n d itio n s, th is p re c isio n in s tr u m e n t a d d s new d im en sio n s o f a c c u ra c y a n d t r e a t m e n t ease. D escrip tives and m edical jo u rn a l rep rin ts on request. (PTY.) LTD. “ Cape Y ork” , 252 Jeppe S t., Johannesburg P .O . B ox 3378 „ . , . „ __ a n d a t President H ouse, 20 Barrack Street, Cape Town. P .O . B ox 195. Telephone 41-1172 Telephone 23-8106 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) Page 6 P H Y S I O T H E R A P Y September, 1960 r e d u c e th e v ita l c a p a c ity a s s u c h a n d o b s tr u c tiv e p u lm o n a r y le s io n s r e d u c e th e tim e d v ita l c a p a c ity . I n th is f a s h io n o b s tr u c tiv e a n d re s tr ic tiv e le s io n s a r e e a s ily d is tin g u is h e d a n d c o m b in a tio n s o f th e tw o c a n b e r e c o g n ise d . T h e fo llo w in g illu s tr a tio n s s h o w n o r m a l e x p ir a tio n w ith a tim in g d e v ic e , th e n a n e x p ir a tio n f r o m a p a tie n t w ith a n o b s tr u c tiv e p u l m o n a r y le s io n a n d th e n a n e x p ir a tio n f ro m a p a t i e n t w ith a re s tr ic tiv e p u l m o n a r y le sio n . N O R M A L E X PIR A T IO N OBSTRU C TIV E LESION RESTR IC TIV E LESION Jr T h e c u r v e o f t h e o b s tr u c tiv e le s io n sh o w s ty p ic a l a ir tr a p p in g . M a x im u m B r e a th in g C a p a c ity . T h is is d e te r m in e d b y g e ttin g th e p a t i e n t to b r e a th e as r a p id ly a n d a s d e e p ly a s p o s s ib le w h ile th e r e s p ir a to r y e x c u r s io n s a r e r e c o r d e d . A n o r m a lly p e r fo r m e d m a x im u m b r e a t h i n g c a p a c ity w ill g iv e a c u r v e a s fo llo w s a n d th is is fo llo w e d b y a n o t h e r c u r v e sh o w in g ty p ic a l a ir tr a p p in g . r A I R T R A P P I N G I t is v a lu a b le to r e p r e s e n t r e s tric tiv e a n d o b s tr u c tiv e le s io n s in th e f o llo w in g f a s h io n : Prediclcd Norm al Vital Capacity I \ O B S T R U C T IV E L E S iO N S \ N O R M A L C \ \ \ v - C O M B IN F .D L E S IO N S R E S T R IC T IV E L E S IO N S JO 20 30 40 50 60 70 80 90 100 110 120 V iliil Capacil> (Pcrccniage Normal) U s in g th is m e th o d o n e c a n d is tin g u is h z o n e s o f .d is a b ility a n d in t h e g r a p h s h o w n z o n e A sh o w s re la tiv e ly n o r m a l p a tie n ts , z o n e B th o s e w ith a m o d e r a te d e g re e o f p u lm o n a r y d is a b ility a n d z o n e C g ro s s d is a b ility . T h is m e th o d h a s a ls o b e e n u s e d f o r a s se s sin g th e d e g re e o f o p e r a tiv e r is k fo r p a tie n ts u n d e r g o in g o p e r a t i o n a n d th o s e in g r o u p C a r e v e ry p o o r ris k s . T h o s e in g r o u p B a ls o a r e p a tie n ts a t ris k a n d c o m p lic a tio n s r e la tin g t o t h e lu n g s a r e t o b e .e x p e c te d . I t is p a r tic u la r ly in th is g r o u p w h e re p h y s io th e r a p y is lik e ly t o b e o f m o s t v a lu e . A d d itio n a l in f o r m a tio n is g iv en b y v a r io u s re fin e m e n ts o f th e p u lm o n a r y f u n c tio n tests. R e s id u a l V o lu m e. T h is m u s t b e m e a s u re d in d ire c tly u sin g a n in d ic a to r g as u s u a lly h e liu m . T h e in d ic a to r g a s is m e a s u re d a n d m ix ed w ith th e p a t i e n t ’s f u n c tio n a l re sid u a l c a p a c ity w h ic h is th e n m e a s u re d f r o m t h e d e g re e o f d ilu tio n o f t h e i n d ic a to r gas. In tra p u lm o n a r y M ix in g a n d D is trib u tio n o f G a se s. A b n o r m a ltie s h e re a r e f o u n d p a r tic u la rly in e m p h y s e m a . T h e t h e o r y is t h a t e v e ry b r e a th ta k e n is e v e n ly d is tr ib u te d t h r o u g h o u t n o r m a l lu n g s a n d th is e v e n d i s t r ib u tio n is g ro s s ly d is tu r b e d in p a tie n ts w ith e m p h y s e m a . E la s ta n c e a n d C o m p lia n c e . T h is im p lie s a m e a s u re m e n t o f th e e la s tic p r o p e rtie s ( o r la c k o f e la s tic p r o p e rtie s ) o f th e lu n g . T h is is m e a s u re d w ith t h e a s s is ta n c e o f a n air-fllled b a llo o n in th e o e s o p h a g u s a n d d e p e n d s o n th e p h y sic a l p rin c ip le o f th e d e g re e o f c h a n g e o f v o lu m e p r o d u c e d b y c h a n g e o f p re s s u re in th e th o r a x . C h a n g e s in t h e c o m p lia n c e o f th e lu n g is f o u n d p a r tic u la r ly in e m p h y s e m a a n d in fib ro s is o f th e lu n g . D iffu sin g C a p a c ity . T h is m e a s u re s t h e c a p a c ity o f th e a lv e o la r m e m b r a n e to a llo w g a sse s to p a s s th r o u g h it to a n d f ro m th e a r te ria l b lo o d . T h is m a y b e m e a s u re d f o r o x y g e n a n d in d ic a to r g a s e s su c h a s c a r b o n m o n o x id e . B lo o d C h e m is try C h a n g e s. T h e s e a r e o f th e g r e a te s t im p o rta n c e a n d th e fa c to rs m e a s u re d a r e th e p 0 2 a n d p C 0 2 o f th e b lo o d a n d o f th e a lv e o la r a ir a s w ell a s th e p la s m a b ic a r b o n a te . O x im e tr y . A r te ria l o x y g e n levels a r e m e a s u re d b e fo re a n d a f te r e x e rc ise a n d a r e f o u n d to fa ll c o n s id e ra b ly in p a tie n ts h a v in g a d e fe c tiv e d iffu s in g c a p a c ity . B ro n c h o s p iro m e try . T h e f u n c tio n o f th e lu n g s m a y b e m e a s u re d s e p a ra te ly u s in g a sp e c ia l d o u b le - lu m e n tu b e w h ic h is p a s se d in to th e le ft m a in b r o n c h u s w h ic h is o b s tr u c te d w ith a n in f la ta b le b a llo o n a t th e e n d o f th e tu b e . T h e o x y g e n u p ta k e o f th e two. lu n g s is m e a s u re d se p a ra te ly . A p p lic a tio n o f P u lm o n a ry F u n c tio n T e sts. D ia g n o s is : E m p h y se m a : M a n y c a se s o f g ro ss e m p h y s e m a a r e e a sily d ia g n o s e d b u t it is so m e tim e s q u ite s u r p r is in g h o w th e c lin ic a l a n d r a d io lo g ic a l a s se s sm e n t m a y b e n o r m a l w h e re p u lm o n a r y f u n c tio n te s ts s h o w a c o n s id e ra b le d e v ia tio n f r o m n o r m a l. T o ta l lu n g c a p a c ity is fre q u e n tly n o r m a l b u t re s id u a l v o lu m e is c o n s id e ra b ly in c re a se d . T h e o t h e r d e v ia tio n s in c lu d e a m a r k e d re d u c tio n in tim e d v ita l c a p a c ity w ith a ir - t r a p p i n g a n d d e la y e d m ix in g o f th e g a sse s in th e lungs.I C o m p lia n c e is re d u c e d a n d th e m a x im u m b r e a th in g c a p a c ity u s u a lly m a r k e d ly re d u c e d w ith a n a i r - tr a p p in g p h e n o m e n o n . B lo o d c h e m is tr y re v e a ls a n a c id o s is w ith in c re a se d p la s m a b ic a r b o n a te , r e d u c tio n in th e a r te ria l o x y g e n level a n d a n in c re a se in th e c a r b o n d io x id e level. F ib ro sis o f th e L u n g s: T o ta l lu n g c a p a c ity is f r e q u e n tly re d u c e d a n d u s u a lly a ll d iv is io n s o f lu n g v o lu m e p a r t a k e in th is r e d u c tio n , th u s th e v ita l c a p a c ity is re d u c e d a n d a l t h o u g h th e tim e d v ita l c a p a c ity is re d u c e d , th is is n o r m a l in p r o p o r t i o n to th e m e a s u re d v ita l c a p a c ity . N o a ir - t r a p p i n g is f o u n d a n d m ix in g is u s u a lly d e la y e d w ith a r e d u c tio n o f p u lm o n a r y c o m p lia n c e . M a x im u m b r e a th in g c a p a c ity is r e d u c e d b u t n o a ir - tr a p p in g p h e n o m e n o n is se en . B lo o d c h e m is tr y is u su a lly n o r m a l e x c e p t fo r a r e d u c tio n o f a r te ria l o x y g e n levels. T e sts f o r d iffu s in g c a p a c ity o f th e lu n g s u s u a lly s h o w a w e ll-m a rk e d re d u c tio n . G ross o b e s ity : T h is is a v e ry in te r e s tin g p h e n o m e n o n . A ll th e d iv is io n s o f p u lm o n a r y f u n c tio n a r e r e d u c e d b u t th is e s p e c ia lly a p p lie s to th e tid a l v o lu m e so t h a t a c o n s id e ra b ly re d u c e d m in u te v o lu m e o c c u rs . A lv e o la r v e n tila tio n b e c o m e s s o m u c h r e d u c e d t h a t a r te r ia l o x y g e n lev els fa ll a n d th e a n o x a e m ia c a u s e s p u lm o n a r y h y p e r te n tio n , r ig h t v e n tr ic u la r h y p e r tr o p h y a n d in so m e ca se s e v en c a r d ia c f a ilu re a n d d e a th f r o m c o r p u lm o n a le . S e c o n d a r y p o ly c y th a e m ia m a y R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) o c c u r T h e in te r e s tin g th in g is t h a t a ll th e s e a b n o r m a litie s c a n r e tu r n to n o r m a l if th e p a t i e n t lo se s th e e x c e ss w e ig h t. H y p o v e n tila tio n S yn d ro m e: 1 P ic k w ic k ia n s y n d r o m e . T h is is v e ry s im ila r t o th e p a t t e r n p ro d u c e d b y g ro s s o b e s ity a n d , in f a c t, g ro s s o b e s ity is o n e o f th e c h a r a c te r is tic s o f th is s y n d r o m e . I n a d d itio n th e re is m a r k e d s o m n ile n c e , c y a n o s is a n d p o ly c y th a e m ia . T h e s y n d r o m e d e riv e s its n a m e , o f c o u r s e , f ro m th e fa t b o y o f ‘T h e P ic k w ic k P a p e r s ’ (C h a r le s D ic k e n s). 2 D a m a g e to th e r e s p ir a to r y c e n tr e . T h is m a y o c c u r a s a re su lt o f e n c e p h a litis a n d th e s e p a tie n ts m a y p re s e n t w ith n o p u lm o n a r y d is a b ility b u t w ith p o ly c y th a e m ia a n d c y a n o sis. O n c e a g a in , th e c h a r a c te r is tic fin d in g is t h a t o f a lv e o la r h y p o v e n tila tio n . P o ly c y th a e m ia : T h e se p a tie n ts a r e f re q u e n tly b r o u g h t fo r p u lm o n a r y f u n c tio n te s ts w ith a view to d e c id in g w h e th e r th is is a p r im a ry d e v ia tio n o f th e b o n e m a r r o w o r s e c o n d a r y to p u lm o n a r y p a th o lo g y . F o r t h e m o s t p a r t, a r t e r i a l o x y g e n levels a r e n o rm a l in p r im a r y p o ly c y th a e m ia a n d c o n s id e ra b ly re d u c e d in p o ly c y th a e m ia d u e t o p u l m o n a r y p a th o lo g y . A fu ll ra n g e o f p u l m o n a r y f u n c tio n te s ts f r e q u e n tly p r o v id e s th e a n s w e r in th is ty p e o f p r o b le m . A ssessm ent o f P ro g r e s s . T h e d e g re e o f b r o n c h o s p a s m is e a sily e s tim a te d u sin g so m e f o rm o f tim e d v ita l c a p a c ity o r m a x im u m b r e a th in g c a p a c ity a n d th e n c o m p a r in g th e r e s u lts b e f o re a n d a f te r a b r o n c h o - d ila to r d r u g . P e r io d ic e s tim a tio n s a ls o giv e a v e ry g o o d id e a o f lo n g te r m th e r a p y . Chronic Bronchitis and Emphysema B y D r . L . D . E R A S M U S , M .B .,B .C h . ( R a n d ) M .D . ( P r e to r ia ) M e m b e r o f t h e F a c u l t y o f M e d ic in e , P r e t o r i a U n iv e r s ity . A L e c tu r e g iv e n to D e le g a te s a n d M e m b e r s o f th e S o u th A fr ic a n S o c ie ty o f P h y s io th e r a p y o n th e f i r s t d a y o f th e “ C h e st C o u r se” , w hich w as h e ld a t th e P re to r ia H o s p ita l P h y sio th e r a p y S c h o o l o n M a y 2 7 th a n d 2 8 th , 1960. A lth o u g h e i th e r o f th e s e c o n d itio n s m a y o c c u r s e p a ra te ly th e y a r e so f re q u e n tly a s s o c ia te d a s a lm o s t to a p p e a r in ­ s e p a ra b le . A n a lle rg ic f a c t o r o r f r a n k b r o n c h ia l a s t h m a is a f re q u e n t a c c o m p a n im e n t. C h r o n ic b r o n c h itis a n d e m p h y s e m a a r e c o n d itio n s o f p a r a m o u n t im p o r ta n c e b e c a u s e o f th e h ig h m o r b id ity a n d e v e n m o r ta lity b r o u g h t a b o u t by a c u te e x a c e rb a tio n s a n d c o m p lic a tio n s . T h e y o c c u r f r e ­ q u e n tly a n d re s u lt in te n s o f t h o u s a n d s o f lo st m a n - h o u r s ev e ry y e a r a n d tr e a t m e n t is f r e q u e n tly e x p e n s iv e , d r a w n o u t a n d u su a lly r e q u ire s h o s p ita liz a tio n .- lin ical H is to ry . E s ta b lis h e d c h r o n ic b r o n c h itis a n d e m p h y s e m a is u s u a lly p re c e d e d fo r se v e ra l y e a r s b y c h r o n ic c o u g h w h ic h is u s u a lly p r o d u c tiv e a n d f o r se v e ra l y e a r s b e f o re th e p a t t e r n b e c o m e s e s ta b lis h e d f re q u e n t a t t a c k s o f a c u te w in te r b r o n c h itis o c c u r. A tta c k s o f a s th m a a r e n o t in f re q u e n t. L a te r p e r s is te n t e x e rtio n a l d y s p n o e a o c c u r s a n d th is m a y be in te rs p e rs e d w ith m o r e a c u te a t t a c k s o f b r o n c h o s p a s m . T h e a t ta c k s o f b r o n c h itis m a y b e s u p p u r a tiv e in n a tu r e d u e to se v ere s e c o n d a r y in fe c tio n a n d e s p e c ia lly in th e e ld e rly d is a b lin g a n d e v e n fa ta l a t t a c k s o f b r o n c h o - p n e u m o n ia m a y o c c u r. T h e s e a t t a c k s f r e q u e n tly p r e c ip ita te c o n g e s tiv e c a rd ia c fa ilu re w h ic h a ls o o c c u r s p a r t i c u l a r l y in th e o ld e r ag e g r o u p w h e n a r te rio s c le r o s is a n d h y p e r te n s io n h a v e b e c o m e e s ta b lis h e d a n d h a v e a d d e d a n o t h e r b u r d e n . S e c o n d a r y p o ly c y th a e m ia f r e q u e n tly in c re a s e s t h e b lo o d v isc o sity a n d o c c a s io n a lly p a p ilo e d e m a a n d b lin d n e s s m a y fo llo w . A etiology. E x te rn a l f a c to r s -are f r e q u e n tly o f th e g r e a te s t im p o r ta n c e a n d th e in c id e n c e o f c h r o n ic b r o n c h itis is h ig h e s t in th o s e a re a s w h e re th e r e is p o l lu tio n o f th e a t m o s p h e r e b y in ­ d u s tr ia l g a se s a n d d u s t. C h r o n ic b r o n c h itis is a ls o m o r e f re q u e n t in h e a v y s m o k e rs . P o l l u t io n o f th e a tm o s p h e r e is ° f ° m i n g a w o r ld w id e p r o b le m . W e b r e a th e a s m u c h a s f h a ' r ^ w e ‘g h t in 24 h o u r s , e q u a l in w e ig h t to tin o o d w e c o n s u m e , b u t f o r m a n y y e a rs it h a s n o t o c c u r r e d to September, 1960 E m p h y s e m a is u s u a lly p e r m a n e n t a n d f re q u e n tly p r o ­ g re ss iv e a n d it is f r e q u e n tly o n ly a s s o c ia te d b r o n c h o s p a s m o r in f e c tio n t h a t c a n b e in flu e n c e d b y t r e a tm e n t. P u lm o n a r y f u n c tio n te s ts h a v e b e e n stu d ie d b e f o re a n d a f t e r th e a p p li­ c a tio n o f p h y s io th e r a p y to th e s e p a tie n ts a n d it a p p e a r s t h a t t h e d e g re e o f p u l m o n a r y f u n c tio n d e v ia tio n is n o t in flu e n c e d b y p h y s io th e r a p y . P a tie n ts w ith p le u r is y a n d p le u r a l e ffu s io n s h o w c o n s id e r ­ a b le im p r o v e m e n t in th e ir v ita l c a p a c ity a s th e c o n d itio n im p ro v e s . C o n g e s tiv e c a r d ia c fa ilu re . T h e d e g re e o f p u lm o n a r y o e d e m a is in d ic a te d b y a r e d u c tio n in t h e v ita l c a p a c ity . I n s o m e in s ta n c e s p u l m o n a r y c o n g e s tio n c a n b e d e te r m in e d a t a n e a r ly s ta g e b y m e a s u r in g th e v ita l c a p a c ity . T h e p ro g re s s o f p a tie n ts w ith w e a k n e s s o f th e r e s p ir a to r y m u sc le s c a n s o m e tim e s b e e ffe c tiv e ly f o llo w e d b y d o in g th e m a x im u m b r e a th in g c a p a c ity te s t. T h is is r e p e a te d a t s h o r t in te r v a ls a n d f a tig u a b ility w ill b e in d ic a te d b y p r o ­ g re ss iv e r e d u c tio n in s u b s e q u e n t te s ts. A s im ila r c lu s te r o f te s ts c a n b e d o n e a t a n in te r v a l o f d a y s o r e v e n w e e k s a n d p r o g re s s fo llo w e d in th is fa s h io n . I n c o n c lu s io n it m a y b e s a id t h a t p u l m o n a r y f u n c tio n te s ts d o n o t re p la c e o t h e r m e th o d s o f a s s e s sin g th e c o n d itio n o f t h e p a t i e n t ’s lu n g s b u t th e y a r e in m a n y in s ta n c e s a v ery v a lu a b le a d ju n c t. Page 7 m e n t o be a s f a s tid io u s a b o u t t h e a i r th e y b r e a th e a s t h e fo o d th e y e a t. W e w ill p r o b a b l y h a v e to p u t u p w ith g ro ss ly c o n ta m in a te d a t m o s p h e r e s f o r m a n y y e a rs t o c o m e . I r r i ­ ta t i o n f r o m d u s t in d u s ty o c c u p a tio n s s u c h a s m in in g is a ls o o f c o n s id e ra b le im p o rta n c e . A n in fe c tiv e a g e n c y is im p o r t a n t a n d t h e c o m m o n e s t in fe c tin g o r g a n is m is H . influenzae b u t a m ix e d b a c te ria l f lo ra is f re q u e n tly f o u n d . I n d iv id u a l p r e d is p o s in g f a c to r s in c lu d e a h e r e d ita r y te n d e n c y a n d a lle rg y . B a sic P a th o lo g y . I t is c o n v e n ie n t to c o n s id e r t h e r e s p i r a t o r y u n it a s c o n ­ sis tin g o f a te r m in a l a n d a r e s p ir a to r y b r o n c h io le le a d in g t o th e a lv e o la r sa c s. T h is m a y b e r e p re s e n te d in th e fo llo w in g f a s h io n in th e n o r m a l a n d th u s w h e n th e r e is b r o n c h ia l in f la m a tio n o r s p a s m i.e., w ith a n o b s tr u c tiv e f a c t o r in tro d u c e d . W ith e m p h y s e m a to u s d ila tio n , r u p t u r e a n d c o a le s c e n c e o f a lv e o la r sa c s o c c u r a s t h e re s u lt o f d e g e n e r a tiv e c h a n g e s in th e e la s tic fib re s o f th e a lv e o la r w a lls. T h e f a c t o r o f b r o n c h ia l o b s t r u c t i o n a n d in f e c tio n is f re q u e n tly s u p e r a d d e d a n d th e re m a y b e a s s o c ia te d i n te r -a lv e o la r fib ro s is. T h e s e c h a n g e s r e s u lt i n : — 1. A m e c h a n ic a l v e n tila to r y d e fic ie n c y w h e r e e x p ir a tio n e s p e c ia lly is d iffic u lt d u e to b r o n c h i o l a r o b s t r u c t i o n , lo ss o f e la s tic tis s u e a n d th e p a t i e n t h a v in g to e x p ire f r o m a n in itia l level o f h y p e r in fla tio n . 2 . In effic ie n t d is t r i b u t i o n o f th e a ir w ith in th e a lv e o la r sa c s o c c u r s a n d t h e im p a ire d d iffu s io n o f t h e g a sse s ■ o c c u r s . 3. I n t u r n a n o x a e m ia a n d c a r b o n d io x id e a c c u m u la tio n o c c u r s in th e b lo o d r e s u ltin g in a c id o s is a n d in c o m p e n ­ s a to r y in c re a s e o f th e b lo o d b ic a r b o n a te . I n te rm s o f p u l m o n a r y f u n c tio n te s ts t h e lu n g v o lu m e m a y r e m a in th e sa m e (a s w ill t h e v ita l c a p a c ity in m a n y in s ta n c e s ) b u t e x p i r a t o r y d iffic u lty r e s u lts in a i r tr a p p in g , {C o n tin u ed o n P a g e 14). P H Y S I O T H E R A P Y R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )