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Au scu ltatory Percussion
S im p le M e t h o d t o D e t e c t P le u r a l E f f u s io n
JOH N R. GUARINO MD JOE C. GUARINO PhD PE
Object ive T o assess a ne w t echn ique f o r t he de t ec t i on o f f 'r ee p l eu r a l
fluid.
Design
1 1 8 c o n s e c u t i v e i n p a ti e n t s w i t h r a d i o lo g i c e v i d e n c e o f f r e e
p l eu r a l fl u id and a con t r o l g r oup o f 175 r andom ly se l ec t ed i npa t i en t s
w e r e e x a m i n e d o v e r a t h r e e -y e a r p e r i o d i n a p r o s p e c t i v e b l i n d s tu d y
by auscu l t a to r y pe r cuss ion ( AP) f o r ev iden ce o f p l eu r a l e ff usion. T he
cu to f f i n t he pe r cuss ion no te by AP is s t ri k ing ly l oud and shar p a t t he
f lu id l eve l and a l l ows p r ec i se d e l inea t ion o f even m in imal amoun t s o f
p l eu r a l fl u id . T he f l u id l eve l was meas u r ed in r e f e r ence t o t h e l a s t r i b .
T he c r i t e r ion f o r de t ec t i on o f p l eu r a l e f f usion by AP was a demo n-
s t r ab le ho r i zon ta l f l u id l eve l a t t he so und cu to f f ac r oss t he pos t e r io r
hemi tho r ax above the l a s t r ib t ha t sh i f t ed wi th l a t e r a l t il t.
Set t ing
A gener a l med ica l and su r g i ca l un ive r s it y - a ff i li a t ed t each ing
Veterans A ffairs hosp ital.
Pa t i e n t s~ p a r t i c i p a n t s Al l inpa t i en t s w er e e l i g ib le . Ready ava i l ab i l i ty
o f examiner s was essen t i a l . Ro ta t i ng t h i r d - and f ou r th - year med ica l
students, reside nts, and senior staf f me mb ers par t icipated .
In t e rv e n t i o n s None .
Ma j o r re su l t s 113 o f t he 118 pa t i en t s wi th r ad io log ic ev iden ce o f
p l eu r a l e f f usion had a d i s t i nc t ho r i zon ta l f l u id l eve l above the l a s t r ib
tha t sh i f ted wi th l a t e r a l ti l t ( sens i t i v i t y = 95 .8 ) . No ne o f t he 175
c o n t r o l p a ti e n ts e x a m i n e d a t r a n d o m s h o w e d e v i d e n c e o f p le u r a l e f-
f us ion by AP examina t ion , wh ich was co nf i r med by ches t r ad iog r aphy
( spec i f i c it y = 100 ) . N ine o f t he 175 pa t i en t s wi th ou t r ad io log ic
ev iden ce o f p l eu r a l e f f us ion had e l e va t ed d i aphr agms tha t s imu la t ed
a f lu id l eve l i n t he exam ina t ion b y AP . E ach o f t he n ine pa t i en t s ,
however , had no sh if t i n t he l eve l wi th l a t e r a l t il t. Subp u lmon ic e f -
f usions w er e r ead i ly d i sp l aced and iden t i f i ed by th i s me th od o f AP .
C o n c l u s i o n s E xamina t ion by AP i s h igh ly sens i t i ve and spec i f i c f o r
the de t ec t i on o f f ree p l eu r a l f lu id , eve n in t he p r e senc e o f obes i t y ,
t h i ckened p l eu r a , l ung masses , pneu monia , and assoc i a t ed l ung d i sease .
T he exam ina t ion co r r e l a t es c lose ly wi th s t andar d and l a t e r a l decub i tus
chest radiography. Pleural ef fusion unsuspected by convent ional means
o f phys i ca l exam ina t ion and und e tec t ab l e by s t andar d ches t r ad iog -
r a p h y c a n r ea d i ly b e d e t e c t e d b y t h e m e t h o d o f AP . T h e e x a m i n a t io n
i s easy t o do and i s pa r t i cu l a rly su i t ed t o en hance de t ec t i on o f p l eu r a l
e f fus ion . As l it t l e a s 50 mL o f f r ee p l eu r a l f l u id can be de t ec t ed .
K e y w o rd s auscu l t a to r y pe r cuss ion ; p l eu r a l e f f us ion ; examina t ion o f
ches t ; auscu l t a ti on o f ches t ; pe r cuss ion o f ches t .
J GEN INTERN MED 1994;9;71 74.
PLEUR LE FFU SIO N i s a f r e q u e n t m a n i f e s t a t i o n o f s e r i o u s
p l e u r o p u l m o n a r y , c a r d i a c , o r e x t r a t h o r a c i c d i s e a s e a n d
n e c e s s i t a t e s s p e c i f i c d i a g n o s is . W h e n t h e p a t i e n t i s u p -
r i gh t , 3 0 0 t o 5 0 0 m L o f f r e e p l e u r a l f l u i d m a y c o l l e c t i n
t h e p o s t e r i o r c o s t o p h r e n i c s u l c u s b u t r e m a i n o b s c u r e d
b y t h e d i a p h r a g m b e f o r e i t b e c o m e s d e t e c t a b l e b y th e
u s u a l m e a n s o f p h y s i c a l e x a m i n a t i o n a n d r o e n t g e n o -
g r a p h i c s t u d i e s . 1 -3 T h e c o n v e n t i o n a l p h y s i c a l e x a m i -
Rece ived f r om the Un iver s i t y o f Wa sh ing ton Schoo l o f M ed ic ine ( JRG) ,
Seat t le , Washington, and the Veterans Affai rs Medical Center ( JRG,
JCG ) and the D epar tm en t o f E ng ineer ing , Bo i se St a te U n iver s i t y ( JCG) ,
Boise, Idaho.
Addr ess co r r espondence and r ep r in t r eques t s t o Dr . Guar ino :
M ed ica l Se r v i ce , VA M edica l C en te r , 500 W est F o r t S t r ee t, Bo i se , I D
83702 .
n a t io n i n c l u d i n g d u l l n e s s t o p e r c u s s io n , d i m i n i s h e d b r e a t h
s o u n d s , v o c a l r e s o n a n c e , a n d t a c t i l e f r e m i t u s i s n o t a t
a ll s e n s i t i v e a n d n o t s u f f i c ie n t l y s p e c i f i c f o r d e t e c t i o n o f
p l e u r a l e f f u s io n . T h e s i g n s m a y b e i m p o s s i b l e t o d is t in -
g u i s h f r o m p l e u r a l t h i c k e n i n g a n d u n d e r l y i n g l u n g d i s- .
e a se . T h e y c a n b e a b s e n t i n p a t i e n t s w i t h o b e s i t y , a t h i c k
c h e s t w a l l , o r s m a l l p l e u r a l e f fu s i o n s. A p h y s i c a l e x a m -
i n a t i o n t h a t i s s i m p l e a n d d i s t i n c t i v e w o u l d b e o f c li n i c a l
v a l u e .
PRIN IPLES
T h e m e t h o d i s b a s e d u p o n t h e p r in c i p l e s o f a u s-
c u l t a to r y p e r c u s s i o n ( A P ) u s e d i n t h e p h y s i c a l e x a m i -
n a t i o n o f t h e c h e s t , h e a d , a n d u r i n a r y b l a d d e r , a n d f o r
t h e d e t e c t i o n o f a s c i te s . 4 -9 W h e n t h e p a t i e n t i s e r e c t ,
f r e e p l e u r a l f lu i d g r a v i t a t e s t o t h e b a s e o f t h e l u n g a n d
c r e a t e s a m a r k e d a c o u s t i c i m p e d a n c e m i s m a t c h b e t w e e n
a i r - c o n t a i n i n g l u n g a n d t h e f lu i d i n t e r f a c e . T h e p o s t e r i o r
c o s t o p h r e n i c s u lc u s , t h e m o s t d e p e n d e n t p a r t o f t h e
t h o r a c i c c a v i ty , i s a d e e p , r e l a t i v e l y i n c o m p l i a n t s l it b e -
t w e e n t h e c h e s t w a l l a n d t h e b o w o f t h e d i a p h r a g m . I n-
v i t ro e x p e r i m e n t s p e r f o r m e d i n o u r l a b o r a t o r y w i t h in -
f l a te d b a l l o o n s i n c o r p o r a t e d w i t h i n t r a n s p a r e n t p l a s t i c
c o n t a i n e r s s i m i l a r in s h a p e a n d c a p a c i t y t o t h e p o s t e r i o r
c o s t o p h r e n i c s u l c u s h a v e s h o w n t h a t m i n i m a l f l ui d v o l-
u m e s p r o d u c e a d i s p r o p o r t i o n a t e r i s e i n t h e f l u i d l e v e l
t h a t c a n b e p r e c i s e l y d e l i n e a t e d a n d m e a s u r e d b y t h e
m e t h o d o f A P . I n an a n e s t h e t i z e d 3 0 - k g s h e e p s u p p o r t e d
u p r ig h t , w e d e m o n s t r a t e d t h a t t h e i n t r o d u c t i o n o f o n l y
2 5 m L o f p h y s i o l o g i c a l s a l i n e s o l u t i o n t h r o u g h a c h e s t
t u b e i n t h e p l e u r a l s p a c e p r o d u c e d a h o r i z o n t a l f lu i d
l e v e l t ha t w a s r e a d i l y d e t e c t e d b y A P . A r i s e in t h e f l u i d
l e v e l w a s d e l i n e a t e d b y A P w i t h e a c h i n c r e m e n t o f 2 5
m L o f t h e p h y s i o l o g i c a l s a l in e s o l u t i o n . W h e n t h e s h e e p
w a s t i l t e d l a te r a l ly a p p r o x i m a t e l y 3 5 f r o m t h e p e r p e n -
d i c u l a r t o w a r d t h e s i d e o f i n f u s io n , t h e f l u i d l e v e l q u i c k l y
s h i f te d t o t h e d e p e n d e n t s i d e a n d r a is e d t h e l e v e l a l o n g
t h e l a t e ra l b o r d e r w i t h a s i m u l t a n e o u s f al l i n t h e l e v e l
m e d i a l l y .
TE HNIQUE
W i t h t h e p a t i e n t s i t t i n g o r s ta n d i n g , h i s o r h e r b a c k
f a c i n g t h e e x a m i n e r , t h e u p p e r e d g e o f t h e t w e l f t h r ib
i s m a r k e d o n e a c h s i d e o f t h e t h o r a x . A f t e r a p p r o x i l n a t c l y
5 m i n u t e s u p r i g h t , f r e e p l e u r a l f l u id g r a v i t a te s t o t h e
b a s e o f t h e l u n g . T h e d i a p h r a g m a t i c p i e c e o f t h e s t e t h -
o s c o p e i s p l a c e d p o s t e r i o r l y w i t h i t s u p p e r e d g e a p -
p r o x i m a t e l y 3 c m b e l o w t h e la s t r i b i n t h e m i d c l a v i c u l a r
71
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7 Guarino Guarino PLEURALEFFUSIONDETECTION
P TI EN T S N D M E T H O D S
F I GU R E 1 . M e t h o d o f a u scu l t a t o ry p ercu ss io n t o d e t e c t t h e l eve l o f
p leura l e f fus ion a r r o w , l e f t s /d e ) a n d t o d e l in e a t e h e p a ra ve r t e b ra l r i a n g l e
o f Gro cco a r ro w , r i g h t s i d e ) .
line. Direct percussion is applied with the free hand
preferably by finger flicking or with the pul p of a finger,
along three or m ore parallel lines from the apex of each
hemithorax perpendicularly down toward the base Fig.
1 ). In the absence of pleural effusion, the percu ssion
note perceived through the apposed stethoscope sounds
dull and remains unchanged, but changes sharply to a
loud note that is striking at the last rib, forming a hor-
izontal baseline across the posterior hemithorax. In the
presen ce of pleural effusion a similar sharp change to a
loud percussion note occurs at the interface of air-con-
taining lung and pleural fluid, approxima ting a horizontal
line across the posterior hemithorax clearly above the
baseline at the last rib. In the a bsence of air in the pleural
space, the fluid level is usually highest laterally towards
the axilla. The distance between the level and the upper
border of the last rib is measured and used as a guide
for thoracentesis and for estimation of fluid volume.
Applying the same technique to the hemithorax op-
posite the effusion, a sharp change to a loud percussion
note clearly defines the borders of the paravertebral
triangular area of Grocco , 1 whos e apex lies along the
spine and who se base ex tend s 6 to 10 cm at a right angle
to the spine Fig. 1). The triangular area can be dull to
conventional percussion but may be difficult to define
with this modality. It is easily and sharply delineated
by AP.
Over a three-year period 19 89- 199 2) , 118 con-
secutivc inpatients with pleural effusion recognizabl e on
chest radiographs and 175 inpatient control subjects
selected at rand om from the medical and surgical wards,
ranging in age from 32 to 96 years mean 64 years),
were examined by AP. Ninety percent of the patients
were men. The technique was developed and taught at
the bedside by the senior investigator on patients with
and without radiologic evi dence of pleural effusion. Pa-
tients with pleural effusion who were teaching cases for
trainees were not part of the study group. Finger-flicking
percussion was done rapidly and gently at about 5-mm
intervals along three parallel lines that ran perpendic-
ularly from the apex of the hemit hora x to its base. Body
contact with only the tip of the fingernail ensures pre-
cision. The examination was usually completed within
5 minutes and required only minimal skill. When the
patient was maintained in the erect position with the
fluid level at equilibrium, the endpo int of the ausco-
percussive note was characteristically sharp, loud, and
precise. A common, inexpensive S prague-Rappaport type
of steth oscope was used in the examination. When the
examiners became proficient and able to identify the
endpoint with eyes closed and with consistent accuracy,
they were asked to examine patients and to mark the
cndpoint in the auscopercussive note. The marked sites
were measured and compared by the examiners. Each
of the 118 inpatients with pleural effusion as well as
each of the 175 randomized con trols was evaluated by
two to three examiners separately and independently.
In the three-year period, 60 medical students, 15 resi-
dents, and five senior staff memb ers wer e trained par-
ticipants. The exam iners we re unaware of the history,
physical, and radiologic findings prior to their evalua-
tion. Which patients had plcural effusion was obtained
from a central source and was known only to the senior
investigator. There was no commun icati on between the
examiners and the senior investigator during the ex-
amination. All patients had a standard physical exami-
nation and standard posterior-anterior and lateral ra-
diography of the che st up on admission. Lateral decubi tus
radiographs were obtained when pleural effusion was
suspected by the radiologist after examining the stan-
dard radiographs. Ultrasonography and computerized
tomography of the chest wer e done for several patients
unrelated to this study. Patients with a horizontal level
above the last rib in the examination by AP suggestive
of pleural effusion wer e tilted laterally with suppo rt ap-
proximately 35 from t he perp endicular , and the ex-
amination was repeated. Corresponding shifts in the level
and changes in the size of the paravertebral triangle of
Grocco in the contralateral lung base were also noted.
To avoid false-positive examinations results, it was
essential to mark the last rib and to keep the upper edge
of the diaphragm atic pie ce wel l b elow this rib. False-
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JOURNAL OF GENERAL NTERNAL MEDICINE V o l u m e 9 February) , 9 9 4 7 3
negative results can occur when patients are examined
too quickly upon arising from recumbency, i.e., before
settling of the pleural fluid. Five minutes upright was
considered sufficient time to establish a fluid level in
nearly all patients with free pleural fluid. With the dia-
phragmatic piece held as described below the last rib,
the location of the diaphragm at the pe riphery at end-
inspiration and end-expiration was easily identified by
a sharp cutoff produc ing a suddenly loud auscopercus-
sive note below and above the last rib, respectively.
RESULTS
All examiners re ported their findings independently
to the senior investigator (JRG). One hundred thirteen
of the 118 patients with pleural effusion accor ding to
the standard and lateral decubitus chest radiographs had
a demonstrable fluid level above the last rib according
to the examinati on by AP, and a distinct shift in the level
by lateral tilt (sensi tivit y = 95.8% ). Of note, a back war d
tilt prod uce d a distinct rise in the fluid level; conversely,
a forward tilt caused a fall in the level. The five patients
who yielded false-negative findings in the initial exam-
ination by AP had been supine approximately two hours.
The fluid level was not discernable until the patients
were upright for 25 to 30 minutes. The chest radiog raphs
for each patient showed fluid loculation, and subsequent
thoracentesis revealed viscous fluid. Each of the five
patients were re-examined by AP at lO-minute intervals
in the erect position. The sensitivity of the AP test for
pleural effusion may thus increase whe n the e xaminati on
is repeated.
Each of eight patients in the study suspe cted to have
subpulmonic effusion by chest radiography, confirmed
by lateral decubitus radiography, had a distinct fluid
level above the last rib in the examination by AP that
shifted with lateral tilt. They were readily identified by
the meth od of AP.
Pleura] effusion was not specifically identified in the
standard conventional physical examinations of the chest
for any of the 118 patients in the admitt ing examination.
The 175 control patients examined at random included
patients with lung masses, pneumonia, lobectomy, dia-
phragm elevation, and unspecified lung disease. None
had evidence o f pleural effusion in the exami nation by
AP or by chest radiograph.
Nine of the control patients with unilateral dia-
phragmatic elevation visible on the chest radiograph had
a horizontal level above the last rib in the examination
by AP, suggesting pleura] effusion. However, none of
these patients had a shift in the level with lateral tilt,
thus none constituted false-positive AP test results for
pleura] effusion (spec ific ity = 100% ).
The paravertebral triangle of dullness of Grocco was
easily elicited in all patients in this study wi th unilateral
pleura] effusion and in those patients with unilateral
diaphragmatic elevation. A lateral tilt of 35 toward the
side with effusion quickly obliterated the triangular area
of dullness in the contralatera l hemithor ax, shifted the
fluid to the dependent side, and raised the fluid level
along the lateral border. The maneuver with a slight
backward tilt facilitated thoracente sis of small effusions
at the posterior axillary line. Within the triangular area
of dullness of Grocco, breath sounds were diminished
to absent. Muffled e-to-a changes may be elicited, and
distant bronchovesicular breathing could be heard in
some patients, suggesting pneumoni c consolidation. The
abnormal findings were quickly obliterated with lateral
tilt toward the side with pleura] effusion, with disap-
peara nce of dullness and e-to-a changes, and return of
normal breath sounds.
Diaphragmatic excursions were easily and precisely
identified at the periphery by AP and normally ranged
from 5 to 6 cm. Of the 118 cases of pleural effusion, 57
were due to malignant neoplasms, 32 to congestive heart
failure, eight to pneumonia, two to empyema, five to
acute pancreatitis, two to pancreatic abscess, three to
ascites, two to nephrotic syndrome, two to traumatic
rib fractures with hemothorax, one to subphrenic ab-
scess, two to lung abscess, and two to pulmonary in-
farctions. Pleural effusion was bilateral in 22 patients,
18 of wh om had conge stiv e heart failure.
For all the patients except the five who had viscous
or loculated fluid, the examiners uniformly concurred
100% o f the time t hat the cutoff in the percussi on note
was striking and precise at the fluid level. When the
patient was maintained in the erect position with the
fluid level at equilibrium, the endpoint in the exami-
nation of the same patient by different examiners varied
by 0.5 cm.
DIS USSION
Subpulmonic effusions are common and often un-
suspected.- They simulate an elevated diaphragm in the
chest radiograph and can be difficult to recognize. The
infrapulmonic fluid is quickly displaced by lateral tilt of
the chest and readily identified by the m eth od o f AP.
Small pleura] effusions obscured in the posterior cos-
tophrenic sulcus or too thin to be recognized in the
lateral decubitus radiograph can bc demonstrate d in the
examination by AP.
Awareness of the triangle of Grocco has clinical
significance. The abnormal physical findings within the
triangle have been mistaken for pneumonic consolida-
tion in the physical examination. The mechanism of
Grocco's triangle is unclear. T ~2 The triangular config-
uration of dullness may be due to compression of the
contralateral lung by the hydrostatic pressure of the
pleura] effusion. When the patient is upright, compres-
sion of the lun g is least at the apex whe re the hydrost atic
pressure is low and maximal at the base where the hy-
drostatic pressure is high. The triangular area is not vis-
ible in the chest radiographs but is sharply delineated
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7
Guarino Guarino PLEUR LEFFUSIONDETECTION
by AP. The lack of radiopaci ty in an area of what is
thought to be compressive atelectasis is confusing. How-
ever, i t should be noted that the radiographic factors for
defini t ion 13 differ from the acoust ic factors i nvolv ed in
the trans missio n of sou nd vibrat ion. 7, 14
The me chanis m of AP involves the ef fec t on the
passage of sound vibr at ions throu gh differe nt media. The
transmission of sound vi brat ions depe nds up on the dif-
ference in the acous t i c impedance values between the
media . The acous t i c impeda nce (Z) o f a mater ia l is the
produc t o f the sound veloci ty (c) wi th in the par t i cu lar
mediu m and the dens i ty (p ) o f the medium:
Z = c - o .
T h e t r a n s m i s s i o n o f s o u n d f r o m a m a t e r i a l w i t h l o w
a c o u s t i c i m p e d a n c e i .e . a i r o r g a s t o a m a t e r i a l w i t h
high acoust ic impedance, i .e. , water or body fluids, is
grea t ly inh ib it ed , permi t t ing sharp del ineat ion of the
boundary a t the a i r - f lu id in ter face in the AP examina-
t ion. Applicat ion of the s te thos cop e confin es and pre-
ven t s d i spersion of sound v ibra t ions genera ted by the
percuss ive no te and markedly enhances the prec i s ion
of the AP examinat ion.
In contrast to AP, the radiographi c factors are chem-
ica l and depend upon e lec t ron dens i ty . The opaci ty o f
the image i s p ropor t ional to the c ube of the a tomic
num ber of the material .
The AP examinat ion is considered a valuable sup-
p leme nt to the convent ional ches t examinat ion to detec t
pleural effusion. The AP examinat ion is highly sensi t ive
and specific and corre lates close ly with the s tandard and
lateral decubi tus chest radiographies . Small amounts of
pleural f luid may yield posi t ive AP examinat ion resul ts
in cases with negat ive radiologic f indings. Serial AP ex-
aminat ions showing a change in the fluid level confirm
the pres enc e of pleural effusion. The AP examinat ion is
especial ly useful to alert the cl inician to the possibi l i ty
of unsuspected p leuropulmona ry , cardiac , o r sys temic
disease, and prompts further s tudy and fol low-up.
The cooperation and assistance of the Medical, Surgical, and Nursing
Services of the Boise Veterans Affairs Medical Center are gratefully
acknowledged. The authors thank Wayne L. Kirk for his laboratory
assistance and Barry Cusack, MD, for review of the manuscript. They
are especially grateful to Paula Carvalho, MD, for her assistance in the
preparation of the manuscript.
R E F E R ENC E S
1. Hinshaw HC, Garland LH. Diseases of the pleura. In: Diseases of
the Chest, 2nd ed. Philadelphia: W. B. Saunders, 1963;592-638.
2. Felson B. The pleura. In: Fundamentals of Chest Roentgenology.
Philadelphia: W. B. Saunders, 1960;183--93.
3. Vladutiu AO. Clinical signs of pleural effusion. In: Pleural Effusion.
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