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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to medical diagnostic apparatus, and more
particularly to a computer based system for pulmonary diagnosis based on
measured performance of the lungs during selected testing.
The use of computer based systems in forming medical diagnoses, and more
particularly in diagnosing pulmonary function, is well known. Evaluation
of pulmonary condition involves measurement of the size of the lungs, the
limitation to air flow, e.g. flow rates, the adequacy of gas exchange
(diffusion), and response to aerosol drugs (bronchodilator response). Such
pulmonary function testing typically generates up to sixty parameters for
evaluation. Manual examination of the results of such testing is tedious
and time consuming. A computer program for calculating and interpreting
standard pulmonary function test data is disclosed by Ellis, Pareja and
Levin in 1975 (Chest Volume 68: Pages 209-213, 1975). This and like
systems were directed principally to identifying abnormal parameters.
While diagnosis can be simplified by focusing on key parameters, this
increases the risk of overlooking subtle anomalies.
As disclosed by Fallat and Snow (Comp. Med. Volume II, No. 3: Pages 14-18,
1984), a program designated "Micropuff" has been developed in an effort to
mirror a clinician's approach to analyzing pulmonary function data,
utilizing a personal computer. The Micropuff program aids interpretation
by first identifying various parameters among those tested as abnormal,
and then applying abnormality flags to a set of rules for generating
conversational text, tailored to the individual physician. Diagnostic
statements generated as a result of this analysis are subject to final
correction by or for the physician, for example through conventional word
processing techniques. Fallat and Snow reported the results of testing, in
which seventy-five percent of the computer generated interpretations were
accepted without modification. Further, substantial time is saved because
the physician edits, rather than creates, the diagnostic text.
While the Micropuff program has been successful in certain respects, it
also has shed light on the need to tailor pulmonary diagnostic systems to
the interpretation habits and syntax of individual physicians. Moreover,
the same physician may wish to interpret pulmonary function test
parameters based on different approaches tailored to special situations,
for example epidemiology studies.
Therefore, it is an object of the present invention to provide a pulmonary
function analysis system which can be modified by the physician in
accordance with his or her analytical approach.
Another object of the invention is to provide pulmonary function diagnostic
apparatus for identifying selected pulmonary function parameters as
abnormal, and further for identifying the degree or extent of abnormality,
in accordance with values predetermined by the physician.
Yet another object is to provide a pulmonary analysis system for generating
preliminary diagnoses of pulmonary function, including textual statements,
wherein the bases for selecting among the textual statements, and content
of the statements themselves, are subject to physician modification.
SUMMARY OF THE INVENTION
To achieve these and other objects, there is provided a diagnostic
apparatus including a first electronic data storage means, and a plurality
of expected values stored in the first data storage means, each expected
value representing a predicted normal level for a pulmonary function. The
apparatus also includes a first data input means for entering a plurality
of expected value ranges into the first data storage means. Each range
corresponds to and encompasses one of the expected values. The first data
input means includes user operable range input means for adjustably
determining the range corresponding to each expected value. Consequently
each range represents a pulmonary function at a level within a normal
range as determined by the user. A second data input means is provided for
entering a plurality of boundary values into the first data storage means.
The boundary values are arranged in sets of consecutively increasing
value, with each set corresponding to one of the ranges and determining,
with respect to the corresponding range, increasing degrees of departure
from the range. The second data input means includes user operable
boundary input means for adjustably determining the boundary values. As a
result, the degrees of departure corresponding to each range are
determined by the physician, and represent a pulmonary function at
increasingly abnormal levels as determined by the physician or user. A
pulmonary function testing means measures a plurality of pulmonary
functions and provides a plurality of performance values to the first data
storage means. Each performance value is based upon a measured pulmonary
function and corresponds to one of the expected values. A processing
means, operatively associated with the first data storage means, compares
each performance value with its corresponding value range, and generates a
first output indicating whether or not the performance value is within the
corresponding range. The processing means also compares each performance
value lying outside of its corresponding range with its corresponding set
of boundary values, and generates a second output indicating a degree of
departure from the corresponding range. A display means, operatively
associated with the processing means, presents the first and second
outputs in a form to facilitate user recognition.
Preferably each range is determined by upper and lower limits respectively
greater than and less than the corresponding predicted value. Degrees of
departure can then be defined by preselected increasing, discrete levels
for a quantity B determined in accordance with the following formula:
B=10(1-M/L)
where B is the extent of the departure, M is a measured performance value,
and L is one of the upper or lower limits, specifically the one nearest
the measured performance value.
A second data storage means can be provided for storing a plurality of
degree of severity labels, each corresponding to one of the degrees of
departure. Preferably a data entry means is connected with the second
storage means and operable by the physician for modifying the degree of
severity labels. The processing means then selects one of the severity
labels in accordance with the determined degree of departure, and
generates the selected label as the second output.
A third storage means can be provided for storing a plurality of pulmonary
condition diagnostic labels. Then, the processing means generates the
second output by providing one of the diagnostic labels and one of the
degrees of severity labels, both selected in accordance with particular
ones of the measured performance values outside of their associated
ranges, and the degree of severity for each of the particular measured
values.
A fourth storage means can include a plurality of textual statements of
pulmonary condition. The processing means selects at least one selected
statement from the available statements in accordance with the particular
ones of the measured performance values outside of their associated ranges
and the degree of abnormality of each particular measured performance
value. The data entry means is usable to selectively modify the textual
statements. The textual statements can relate either to the normality or
abnormality of pulmonary function such as total lung capacity, forced
expiratory volume, or residual volume, or to general pulmonary conditions
or diseases, such as obstructive airways disease or a type of such disease
such as emphysema.
Thus, in accordance with the present invention, a physician can select the
size of the "normal" range about a normal expected value for each measured
parameter. The physician can define ranges, beyond the normal range, of
stepped degrees of abnormality, and designate a label corresponding to
each degree and describing the abnormal condition, e.g. mild, moderately
severe, or severe. Finally, textual statements may be modified, for
example to change "obstructive airways disease" to "obstructive airways
defect", or to change "is normal" to "is within normal limits. Thus,
apparatus in accordance with the present invention substantially enhances
the computer assisted analysis of pulmonary function data, in that the
analysis can be modified in accordance with an individual physician's
analytical approach and syntax.
IN THE DRAWINGS
For a better appreciation of the above and other features and advantages,
reference is made to the following detailed description and drawings, in
which:
FIG. 1 is a block diagram of a pulmonary function analysis system
constructed in accordance with the present invention; and
FIGS. 2, 3 and 4 are flow charts illustrating the analysis of pulmonary
function parameters utilizing the system of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings, there is shown in FIG. 1 a system for
measuring parameters of pulmonary function, and generating a preliminary
diagnosis of pulmonary condition, based upon comparison of measured
parameters with expected values for such parameters. At the heart of the
system is a central computer 16, which can be a personal comptuer, for
example an IBM AT personal computer. Computer 16 receives and stores data
from a number of sources, including a data entry device 18, preferably a
keyboard operatively connected to the computer over a line 20. Data
entered over line 20 includes preliminary information prior to testing an
individual patient, for example the expected values for a multiplicity of
parameters reflecting normal levels for pulmonary functions and
conditions, for example air flows and lung volumes, based on the patient's
age, height and sex.
The system includes lung measurement equipment for providing data to
computer 16 during testing of the patient. A volume measuring device 22,
for example a plethysmograph nitrogen wash-out circuit, measures and
provides the computer with lung volume parameters such as slow vital
capacity (SVC), residual volume (RV), thoracic gas volume (TGV), total
lung capacity (TLC), and alveolar volume (VA).
Lung mechanics parameters are measured and provided to the computer by a
mechanics measuring device 24, typically a spirometer or flow device.
Parameters measured by the spirometer include forced vital capacity (FVC)
measuring vital capacity performed with a maximally forced expiratory
effort, forced expiratory volume (FEV.sub.T where T is the number of
seconds of FVC), forced expiratory flow (FEX.sub.X where X is the amount
of FVC exhaled when the measurement is made), and airway resistance
(R.sub.AW). Diffusion measuring equipment 26, for example a gas
chromatograph, measures and provides the lung diffusing capacity
(DL.sub.CO), based on a single breath or steady-state measurement.
Data entry device 18 also provides information for storage in a number of
data files, including a parameter limit file 28, a configuration file 30
and a statement file 32. These files, in turn, provide such information to
a processor 34 operatively connected to computer 16.
The output of computer 16 is provided to a printer 38, a video display
terminal 40 and a data storage medium such as a disk drive 41. The display
terminal permits the physician or other user to monitor preliminary
diagnostic results during testing, while the printer provides the same
results in permanent form. These results include the measured parameters,
the identification of particular parameters, if any, falling outside of a
chosen range for normal and therefore identified as "abnormal", and
textual statements, e.g. that the lung functions are normal, or that an
obstructive airways disease, for example asthma, is indicated. A diagnosed
disease or any other abnormal condition can be further identified as to
degree of severity.
A significant problem with prior art pulmonary diagnostic systems,
particularly computer enhanced systems, stems from the tendency in
individual experts to interpret the same data in different ways. Two
physicians may disagree as to whether a certain parameter is "abnormal",
or as to whether an abnormality is insignificant, or sufficiently severe
to merit attention. Names identifying various pulmonary conditions vary
among physicians and among different regions of the country.
In accordance with the present invention, a preliminary diagnosis can be
tailored in accordance with individual preferences and styles of
physicians or other experts. More particularly, data files 28, 30 and 32
are all subject to modification, with changes effected conveniently by the
user through keyboard 18.
Parameter limit file 28 stores a plurality of abnormality limits, each
limit related to a parameter. The parameter may correspond to a normal
value for a pulmonary function or condition, or may reflect the
relationship between or among two or more such values, for example
diffusing capacity divided by alveolar volume. The following Table I is
exemplary of the type of data stored in parameter limit file 28:
TABLE I
______________________________________
PARAMETER ABNORMALITY LIMITS
______________________________________
Lung Mechanics
FVC (l) 2.0
FEV (l) 2.0
FEV.sup.1 (l) 2.0
FEV.sup.3 /FVC (%) 0.2
FEF.sup.1 - 50%
(l/sec) 2.0
FEF - max (l/sec) 2.0
Lung Volumes
SVC (l) 2.0
RV (n.sub.2) (l) 3.0
TLC (n.sub.2) (l) 2.0
RV (pleth) (l) 2.0
TLC (pleth) (l) 2.0
TGV (pleth) (l) 2.0
R.sub.aw 2.0, 0.2-2.5
Diffusing Capacity
DL.sub.co (ml/min/mmHg) 2.0
Alveolar volume
(l) 2.0
TLC (SB) (l) 2.0
Blood Gases (Torr.) 2.0
P.sub.a O.sub.2
______________________________________
Other parameters may be included in file 28, the above being exemplary. The
data is arranged in three columns, with the first (left) column
identifying the parameter by its recognized acronym, the second column
identifying the units of measurement, and the third column identifying the
abnormality limit. For each of the parameters, processor 34 utilizes the
abnormality limit to define a normal range about an expected value of that
parameter, in accordance with the following formulas:
LL=P.times.(10-A/10)
UL=P.times.(10+A)/10
where LL is the lower limit of the normal range, UL is the upper limit, P
is the predicted or expected value of the parameter, and A is the
abnormality limit from the third column. Thus, for an abnormality limit of
2.0, LL is 80% of P, and UL is 120% of P.
It is the physician or other expert, selecting abnormality limits through
keyboard 18, who establishes the normal range for each parameter, based
upon what he or she considers an acceptable normal range about a given
expected parameter.
Configuration file 30 is used by processor 34 along with the parameter
limit file. The configuration file contains data in accordance with the
following Table II:
TABLE II
______________________________________
CONFIGURATION FILE
no significant bronchodilator response
label
a slight bronchodilator response
label
a good bronchodilator response
label
an excellent bronchodilator response
label
minimal degree of severity
label
mild degree of severity
label
moderate degree of severity
label
moderately severe
degree of severity
label
severe degree of severity
label
0.0 degree breakpoint
1.0 degree breakpoint
2.0 degree breakpoint
3.0 degree breakpoint
4.0 degree breakpoint
______________________________________
The configuration file can further provide for selecting normal ranges
based on standard deviation rather than on percent, and for selecting the
automatic system as opposed to a manual option.
All entries in the lefthand column of Table II can be modified using
keyboard 18. The first four entries are possible descriptions for a
measured improvement in lung performance, following administration of a
bronchodilator. The remaining entries are related to the contents of
parameter limit file 28, in that once a measured parameter (or a
calculated parameter based upon measured values) is found to be outside of
the expected normal range, its degree of abnormality is determined in
accordance with the breakpoint values in configuration file 30. The degree
of abnormality or extent of departure from normal is determined in
accordance with the formula:
B=10(1-M/L)
where B is the extent of departure, M is the measured performance value and
L is the particular one of the upper and lower limits (UL and LL) which is
nearest to the measured performance value. The degree of severity labels
are selected based on a comparison of the quantity B with the degree
breakpoints. For example, in accordance with Table II, if the quantity B
is greater than 0 and up to 1.0, the abnormality is defined as "minimal",
while if B is between 3.0 and 4.0, the abnormality is labeled "moderately
severe".
Accordingly, using keyboard 18 the physician can interchange labels, for
example substituting "no substantial" for "no significant", or by changing
one or more breakpoints. And, given the dependence of the breakpoint
formula upon values for the upper and lower limits of the normal range,
the physician in effect modifies the breakpoints when he or she modifies
an abnormality value.
Statement file 32 contains a "dictionary" of numbered textual statements
relating to pulmonary function or condition, and related diagnostic
information. The following Table III includes exemplary entries:
TABLE III - STATEMENT DICTIONARY
1. Lung volumes are within normal limits.
5. The TLC, FRC and RV are increased indicating over-inflation.
6. The lung volumes are reduced.
27. Following administration of bronchodilators, there is .sub.-- *.sub.--
response.
51. There is excess variability between efforts which makes it impossible
to adequately evaluate the flow volume loops.
55. The FVC, FEV.sub.1, FEV.sub.1 /FVC ratio, and FEF 25-75% are reduced
indicating airway obstruction.
64. The reduced diffusing capacity indicates a .sub.-- *.sub.-- loss of
functional alveolar capillary surface.
109. .sub.-- *.sub.-- airway obstruction and overinflation are present.
121. The MVV is reduced more than the FEV.sub.1 suggesting poor effort or
concurrent neuromuscular disease.
163. The TLC determined by plethysmography is inconsistent with the values
obtained by nitrogen wash-out and the diffusing capacity. Re-assessment of
the plethysmography value is suggested.
164. The alveolar volume determined by the single breath diffusing capacity
is larger than the total lung capacity. Reassessment of lung volume
measurements is suggested.
*: Replaced with a selected bronchodilator response label or severity label
from Table II
As seen from the above exemplary statements, statement file 32 contains a
variety of types of statements, including simple statements as to the
normality or abnormality of given parameters, relating to preliminary
diagnoses of conditions such as obstructed airways, and even statements
suggesting further testing based on lack of complete or incongruous
results. Statement file 32 also includes diagnostic labels for pulmonary
condition, for example normal pulmonary function, asthma, bronchitis, etc.
Processor 34 selects one or more labels from statement file 32 in
accordance with the settings in data files 28 and 30, and pursuant to
preselected algorithms as is later explained.
With expected parameter data appropriate to a particular patient entered
into computer 16, and with data files 28, 30 and 32 modified in accordance
with the preference of the physician, the patient is instructed
alternatively to breathe normally and in a forced manner, and lung
function and performance are measured with measurement equipment 22, 24
and 26. The output of the equipment is provided to computer 16, thus to
generate actual or measured parameters. Processor 34 compares the measured
parameters with the previously stored expected parameters, determining
abnormality and degree of abnormality in accordance with data files 28 and
30, and providing to computer 16 selected statements from data file 32 in
accordance with abnormality and degrees of abnormality, for output to
printer 38, disk drive 41 and display terminal 40.
In accordance with this method, the first step performed by processor 34 is
the detection of abnormalities, illustrated in FIG. 2. Measured pulmonary
data are evaluated in sequence, with spirometry data evaluated first as
indicated at 42. The evaluation consists of comparing each parameter with
its corresponding predicted value to determine whether it lies within or
outside of the corresponding normal range, as predetermined by the
physician when selecting the abnormality limit. At this stage for example,
the following lung mechanics parameters may be evaluated: FVC (forced
vital capacity), FEV.sub.t (timed forced expiratory volume, where t is the
time in seconds of FVC), FEF.sub.x (forced expiratory flow, where x is the
portion of percentage of the FVC curve), and MVV (maximal voluntary
ventilation). Each of these parameters is evaluated as either normal or
abnormal. If all variables are within their corresponding normal ranges, a
normal statement is generated. Alternatively, a poor effort is indicated.
Then the process moves to the next stage. An absence of data in any given
stage also results in a move to the next category.
At the next stage, one more lung mechanics parameter, R.sub.aw (airway
resistance), is evaluated individually at 44. If measured airway
resistance is greater than the upper limit of normal, then the abnormal
indication is given, while if the measured value is equal to or less than
the upper limit of normal, then the normal statement is the result.
As indicated at 46, the method for determining volume data is noted for
further evaluation if necessary, particularly as to whether the
methodology is plethysmography, nitrogen washout, or single breath
diffusion.
At the next stage, lung volume parameters are evaluated as indicated at 48.
The volume parameters include TLC (total lung capacity), SVC (slow vital
capacity), FRC (functional residual capacity), and RV (residual volume).
Relationships between parameters are also evaluated, for example RV/TLC
and FEV.sub.1 /FVC. The lung volume parameters are evaluated as abnormally
high, abnormally low, or normal, provided that measurements have been
taken and a statement is available.
The next stage, indicated at 50, occurs only if a bronchodilating
medication is administered during testing, and involves a re-measurement
of previously indicated parameters following such administration. A
significant response is indicated if pulmonary function experiences marked
improvement after bronchodilator administration, while a paradox is
indicated if performance is shown as worse after administration. The other
optional result based on actual data is an indication of no significant
response to the administration of a bronchodilator. Lung mechanics
parameters re-evaluated at this stage include FVC, FEV.sub.1, FEV.sub.3,
FEF (25-75%), TLC and R.sub.aw.
Diffusion is evaluated at 52 using DL.sub.CO (corrected for hemoglobin if
available), alveolar volume and the ratio of DL to alveolar volume
(DL/VA). Differences between alveolar volume measured during single breath
diffusing capacity procedure are compared with nitrogen wash-out or
plethysmography measurements of TLC. Diffusion is evaluated and reported
as increased, decreased or normal.
Thus, in accordance with the process illustrated in FIG. 2, processor 34
compares previously stored parameters with measured data to generate a
series of flags identifying various parameters as either normal or
abnormal. Further, however, processor 34 generates a clinical pattern
evaluation at 54, shown in greater detail in the flow chart of FIGS. 3 and
4. A significant feature of the present invention resides in the
reevaluation of primary flags based on the presence of multiple
abnormalities, determined in accordance with the flow charts of FIGS. 3
and 4.
The first step in clinical pattern evaluation is identifying the presence
of obstructive airways disease (OAD). The presence of OAD and its degree
of severity are determined in accordance with the following formula:
OAD degree=FEV.sub.1 /FVC+(FEF 25-75%/5)+(FEF 75%/20)
The degree of severity number (breakpoint) from data file 30 is used for
each quantity in this equation, e.g. FEV.sub.1 /FVC will equal 1, 2, 3 or
4 if abnormality is found and the breakpoints are set as indicated in
Table II above. Of course, if FEV.sub.1 /FVC was found to be normal, its
severity degree is 0. As indicated in FIG. 3, the pattern evaluation
process proceeds along one of two paths from an obstructed airways disease
(OAD) decision 56, depending upon whether OAD is indicated. While the
above mathematical algorithm for OAD is preferred, the scope of this
invention includes alternative algorithms.
In either event, the next step is to indicate whether or not diffusion
measurements were taken during testing, as indicated respectively at 58
and 60. If not, the alternative outputs are A and H, depending upon
whether OAD was previously indicated. If measurements were taken, the
final indication or resultant in FIG. 3 is based on whether the diffusion
is normal, increased, or reduced. Thus, the resultant of FIG. 3, which is
provided as the input to the program portion shown in FIG. 4 at 62, can be
one of eight alternatives as indicated at Table IV:
TABLE IV
______________________________________
A no DL.sub.CO, OAD
B increased DL.sub.CO, OAD
C normal DL.sub.CO, OAD
D reduced DL.sub.CO, OAD
E increased DL.sub.CO, no OAD
F normal DL.sub.CO, no OAD
G reduced DL.sub.CO, no OAD
H no DL.sub.CO, no OAD
______________________________________
The resultant, i.e. one of A-H, is re-evaluated as to whether lung volume
measurements were taken during testing, at 64. If not, and if no
bronchodilator was administered, a statement to that effect is indicated
as at 66. If a bronchodilator was administered, then a BD response at 68
is evaluated, with one of three resultants, i.e. either a significant
response, no significant response, or a paradoxical response to the
bronchodilator.
Alternatively, if lung volume measurements were taken (the "YES" output of
evaluation 64), total lung capacity is reevaluated at 70 for an indication
that it is increased, normal or reduced. Then, the presence of data
following bronchodilator administration is assessed in each case at 72, 74
and 76, respectively, and the nature of the bronchodilator response is
evaluated at 78, 80 and 82, respectively, yielding one of the three
results explained in connection with the evaluation at 68.
To summarize, the pattern recognition illustrated in FIGS. 3 and 4 proceeds
as follows:
(1) Is OAD indicated?
(2) Were diffusion measurements obtained?
If so, is diffusion normal, increased, or reduced?
(3) Were lung volume measurements obtained? If so, are volume parameters
normal, increased, or reduced?
(4) Was a bronchodilator administered? If so, was the response significant,
not significant, or a paradox?
Pattern recognition and initial abnormality detection (FIG. 2) are
preferably accomplished by processor 34, programmed in accordance with
computer programming techniques known to those skilled in the art.
To further explain the pattern evaluation of FIGS. 3 and 4, the following
examples are presented, each corresponding to the examination of a
particular patient.
EXAMPLE I
__________________________________________________________________________
MEDICAL GRAPHICS
350 OAKGROVE PARKWAY
ST. PAUL, MN 55110
Name: CONSULT Date: 1/17/86 ID: 119
Age: 47 yr Sex: M Height: 175.00 cm Weight: 101.00 kg
Dr. Technician: Room: OP
Pack Years: 15 yr Years quit: 10 yr Packs/Day: 0.00
Dyspnea History: Only ofter Severe exertion
Diagnosis:
CHRONIC BRONCHITIS
DYSPNEA ON EXERTION
__________________________________________________________________________
PRE-BRONCH POST-BRONCH
Pred
Pre
% Pred
# SD
Post
% Pred
% Change
__________________________________________________________________________
LUNG VOLUMES
SVC (L) 4.64
4.88
105 0.43
RV (Pleth) 2.01
1.42
71 -1.55
TGV (Pleth) 3.55
3.15
89 -0.71
TLC (Pleth) 6.64
6.30
95 -0.51
RV/TLC (Pleth)
30 23
TLC (N2) (L) 6.64
4.88
73 -2.63
Alveolar Volume (L)
6.61
7.42
112 0.98
LUNG MECHANICS
FEV1 (L) 3.66
4.01
110 0.70
FVC (L) 4.64
4.78
103 0.25
FEV1/FVC (%) 79 84
FEV3 (L) 4.65
FEF MAX (L/sec)
8.68
13.49
155 9.08
FEF 25-75% (L/sec)
3.67
3.89
106 0.88
FEF 75% (L/sec)
1.48
1.83
124 1.84
MVV (L/min) 148 146
99 0
Raw (cmH2O/L/s)
0.2-2.5
1.09
DIFFUSION
DLCO-unc (ml/min/mmHg)
33.24
28.64
86
DLCO-cor (ml/min/mmHg)
28.34
DLCO/VA 4.71
3.86
82 -1.16
__________________________________________________________________________
Interpretation: The FVC, FEV1, FEV1/FVC ratio and FEF25-75% are within
normal limits.
The MVV is within normal limits. The airway resistance is normal. The
alveolar volume
determined by the single breath diffusing capacity is larger than the
total lung capacity.
Re-assessment of lung volume measurements is suggested. Lung Volumes are
within normal
limits. The diffusing capacity is normal.
Pulmonary Function Diagnosis:
Normal Pulmonary Function
This preliminary report should not be used clinically unless reviewed and
signed by a physician.
John Smith, M.D.
__________________________________________________________________________
Lung volume, lung mechanics and diffusion parameters all were found to be
within normal limits. However, the lung volume measured by the single
breath diffusion method (VA) is indicated as larger than the lung volume
measured by plethysmography (TLC), indicating one of these measurements is
in error. Thus, in addition to statements from data file 32 indicating
normal parameters, a statement is added | | |
