Pulmonary Function Testing

   
Lecture Notes, etc.:

                            a. Mechanics & Types:

Prevalence of lung disease depends on the population, but in

general obstructive is 70%, restrictive is 20-25% and vascular is

5-10%. Only the latter cannot be screened for reliably with

PFT's. An ideal screening test would identify every patient with

a disease regardless of stage or severity (high sensitivity) and

exclude those without the disease (high specificity.)

Spirometry measures the volume of air that a subject inspires and

expires. The Spirometer has an accuracy of +/- 5% for FVC and

FEV1

Water seal, Rolling seal, Bellows/ diaphragm types...Computerized

Pneumotachnograph **

b. Vitalogram System

c. Quality Control

-leak proof connections *

-adequate, reproduceable effort

-pattern of volume/time tracing (dynamic & static)

-Need Syringe, Valve and tool... check at one liter intervals

-Need only recalibrate if excessive use (eg. mass screening) or

very infrequent use.

-Sterilization

When contamination (w/ TB or AIDS, etc.) is suspected

May replace the bellows and recalibrate or use cidex method.

d. Patient-Operator Relationship *

-Full cooperation of the patient

-Uninhibited performance in a loud voice; instruction,

encouragement, or exhortation

-Deliberate Malingerers; (insurance, pension, compensation, or

disability claims)

-Lightly Clothed (tight ties, collars, corsets, bras, etc.)

-Remove loose dentures

-Cough Spirogram

e. Technique

Same person doing PFT _ consistency. Experience in a hospital PFT Lab.

-Position * : standing, sitting/comfort (have a chair ready in case

of dizziness or need to rest); Debilitated patients may be examined

in a semirecumbant position (although different normal values may

be needed)

-Nose Clips (vs hold nose)/vs discomfort...cleft palate must have

nose clipped.

Static Test *

Expiratory Slow Vital Capacity...Inspiratory)...Maximal Inspiration

(topped-off with nose snorts)

* Closed circuit Helium dilution technique for FRC, RV,

TLC...Spirometer is filled with a known volume of oxygen to which

helium has been added to give 10% mix...Patient then rebreathes

this mixture until a new stable mixture occurs, usually w/in 3 min

and final He concentration is measured and FRC is calculated.

Dynamic Test *

(Forced Expiratory Flows): how fast you can blow after maximal

inspiration (from TLC!!)...Demonstrate thru a mouthpiece for the

patient (make it explosive hiss/wheeze by obstructing end) and

demonstrate effort "blow until I tell you to stop"...Lips closed

around mouthpiece, make sure tongue is not inside it/malingerers;

"faster! faster!! keep blowing!!!".

In normal individuals a standard 6 sec paper can be used; with

airways obstruction, a 12-second timing scale is needed. Child

can perform FVC in under 1 sec; teenager 1-2 seconds; adult athlete

in 1.5-3 sec; normal, nonsmoking adult 3-4 sec (increases with

age); cigarette smoker >=5 seconds; chest disease (COPD) 5-10

(severe 25 sec)...Note the curve is approaching horizontal when no

further volume change occurs and thus at FRC and the end of

FVC...Reproducible FVC by at least one repeat within 5% of the

highest tracing/ watch for fatigue and allow adequate recovery (vs

neuromuscular ds!!!) or paroxysms of a propagative cough in COPD

patient may limit reproducibility.

Allow 2 minutes between FVC, especially with severe airway

obstruction. The maneuver may precipitate bronchospasm and

tissues / MDI should be available.

-Experience with a hands on Pulmonary function lab is suggested.


Let Children practice thru the mouthpiece...Blow out a candle

technique...using a flash light. Pediatric PFT underutilized

despite asthma and chronic cough are quite common.

e. Sources of Error:

Lack of cooperation

very severe airway obstruction may make the patient too dyspneic

to cooperate

small children (pediatric mouthpiece!)

Valid Vitalgram curves * 1) FVC never concave left to right (a),

* 2) Should be steepest at the beginning (b), * 3) Should finish

horizontally at the end *

Poor effort:

1. FVC < SVC

2. FVC < 6-7 sec

3. PEFR is not sharp and rapid on Flow/Volume loop

4. If MVV is < .8 * 40 * FEV1 and FEF 200-1200 is normal

II. Pathophysiology

* There are 3 aspects of pulmonary function: Perfusion, the passage

of blood thru the pulmonary vasculature; Diffusion, exchange of

oxygen for carbon dioxide across the alveolar-capillary membrane;

and Ventilation, the exchange of air between the alveoli and the

atmosphere. Spirometry (plesthygography, planimetry, gas

dilution) assesses ventilation; arterial blood gases asess

perfusion; and DLco assesses diffusion.

Representation of the lung, thorax and airway dynamics. **

Lung Volumes * :

anatomical measurements

-Vital Capacity (VC) is the amount of air that can be expired after

a maximal inspiration (slow and forced)

-Residual Volume (RV) (+VC=TLC): air left in the lung after a

maximal expiration. (= anatomic + physiologic dead

space)...Increased in Emphysema at the expense of VC...Inc

TLC...Measured by He/N2 dilution curves and washout,

Plethysmography, or X-ray.

Static Lung Volumes...TLC= (IRC+TV+ERV+RV) (IC+FRC) (VC+RV)...%'s.

Sometimes FVC will improve post BD because of a decrease in RV by

relieving air trapping. If the SVC-FVC > 250 cc this suggests air

trapping especially in emphysema with the high expiratory force

collapsing the airways and not allowing all the air out. Also may

reflect effort. Air Trapping suggested when FRCplethsm / FRC Or

when FRCpleth - FRC He > 200cc, and RV/TLC > 120% * pred

* Surfactant and Radial Traction:

There are 300 million alveoli each lined with surfactant (which is

a surface liquid in which the molecules are more attracted to

themselves than they are to the surrounding air...this leads to

surface tension and keeps the fluid surface together.) The

surface tension from all of the alveoli accounts for a majority of

the elastic recoil of the lung (eg. the force to expire and draw

the surface together as well as keeping alveoli open.) This force

is transmitted through the lung tissue and acts as a force keeping

the airways open. This is radial traction. In emphysema, with

destruction of the alveolar sacs and septa by destructive factors

(cigarettes, Alpha 1 antitrypsin, oxygen radicals and pmns) the

surfactant is lost and radial traction. This occurs predominately

in expiration when a positive alveolar pressure is transmitted to

the airways and can no longer be countered by radial traction.

Dynamic Lung Volumes *

Dynamic Flows were introduced 35 yrs ago by Gaensler  Either a

Volume/Time or a * Flow/Volume format. Flow/Volume records

expiratory flow rates from TLC to RV in L/sec.

Maximum Expiratory flow rates depend on:

a. The size of the lungs (bigger=larger _ normals)

b. Lung Volume at which flow is measured (Max Flow at TLC is

higher than at FRC...At most lung volumes it is not true that the

harder one tries, the higher the FEF will be...only modest effort

is needed to reach flow limitation _ want PFT to be independent

of effort!!)

c. Lung Disease (asthma, COPD, CF)

In normal people about 85% of airway resistance is in the larger

airways * of 2mm or greater; although the small airways account for

the vast majority of total cross sectional area.

Increased Raw by: Upper airway lesions (tumors, foreign bodies,

granulomata) or Peripheral Airway lesions (bronchitis,

bronchiectasis, bronchiolitis and Asthma)

Increased compliance is seen with Emphysema

* PEFR is in the first .1 sec of FVC & is very effort dependent.

Peak Flow is at the top and is most effort dependent...cough

tracing...muscular!!! also the effort dependent segment is affected

by the caliber of the large central airways. Peak inspiratory

flow rate is slower than PEFR/ Upper airway obstruction. (Asthma

and bronchitis also have some inspiratory flow restriction,

emphysema typically does not)

When a person is breathing slowly or rapidly, his normal

expirations are passive (eg. no muscular contraction), depending

on the tendency of the chest wall and the lungs to recoil after

inspiration...Forced expiration is an effort and active (muscular)

process.

FEV (L) * is the greatest volume of air that a person can exhale

during a specific phase of expiration

FEF (L/min) is how rapidly can a person exhale a specific volume.

These flows are separate and sequential reflecting different

segments of the resp tree. FEF 25-75% = small airways (when FEV1

and FEV1% are normal).

III. * Why do Spirometry?

* Diagnosis: (not dx'tic)

Control: (30-50 cc/yr decrease in volume/ progression or recession)

Normal Individuals will lose 28 cc/ yr in FEV1 after the age of

18 yo...Pt with COPD have an 80-90 cc/yr accelerated loss in FEV1.

Use example of a saw mill worker with 218cc fall in FEV1 in one

yr and tx w/ steroids for complete reversal.

Classification: Obstructive or Restrictive or Mixed

Selection: Sx, Anaesthesia, NMT, Rehab, Exercise, etc.

Treatment: MDI, Theoph, Beta agonists, Atropine like, NMT, steroids


Prognosis: (post bd FEV1!!!) Abn FEV1/FVC is predictive of

survival.

Confirm or exclude a clinical diagnosis (asthma, obstruction, DLco

w/ ILD)

Provoke an abnormality (% change/mg of provoking agent)

Response to treatment...post BD, Asthma, Studies, post provokative

agent give BD...exercise

Surgical decisions by degree of abnormality / severity of

abnormality.

* Preoperative PFT

-Thoracic Sx

-Upper Abdominal Sx

-Heavy Cigarettes and Cough hx

-Obese Patients

-> 70 y.o.

-Pulmonary Disease

ABG's as well

Increases risk of Postop complications / morbidity and mortality


-TLC and all volumes decrease (not on extremity Sx...most with

thoracic/Upper abd)

* Check patient at his best and use as baseline lung function over

time, eg. destructive factors over time in cigarette

smokers...Objective evidence is necessary (just like ABG's must be

ordered to assess hypoxia) because the pt's assessment of flow

rates has been shown to be inaccurate

Value of specific drugs, eg steroids, theophylline, etc...immediate

and long term effects

Epidemiologic studies in specific populations (ideally to establish

a particular set of normals for the area and people you are

testing) or with industry (eg. asbestos exposure/ Firestone,

Farmer's...Air polution)...different races or genetic types

Claims in disability, impairment, compensation, insurance claims,

pension etc

Nasal provocation with nasal flow

Standard Screening

Additional Assessment

* Restriction

Obstruction

Reversible

Irreversible

Bronchial Hyperreactivity

Chronic Airways Obstruction

Asthma

Emphysema

Bronchiectasis

Kyphoscoliosis

Spondylitis

Pectus Excavatum

Diffuse Interstitial Fibrosis

Sarcoidosis

Refer to Complete PFT if:

-Interstitial Lung ds.

-Respiratory Muscle abn

-Apneas

-scoliosis

-Severe chronic lung ds

-congenital deformities

IV. Differential Diagnosis

Clinical diagnosis cannot be made by spirometry; but is often

supported or excluded. Obstruction and Restriction criteria.

* Obstruction:

When ventilation is disturbed by an increase in Raw (decrease in

Sgaw) an Obstructive Ventilatory Defect is present. Narrowing of

the airways, increasing airway resistance and decreasing airways

conductance slowing the speed of expired gas. In the first part

of the FES is very effort dependent (PEFR, FEV1, etc) and reflects

the function of the larger, upper airways. The smaller airways

are reflected in the middle expiratory rates (especially FEF

25-75%) and are less effort dependant. If obstruction is present

reversibility must be assessed with bronchodilator response (

>15-25% improvement for reversibility.) Provocation tests can be

attempted as well (eg. specific allergens, exercise, cold air, warm

air, drying, methacholine, histamine, etc.) Greater than 20%

decrease in FEV1.

Upper Airway Disease: Pharyngeal & Laryngeal tumor, edema, or

infection; foreign body; Tracheal tumors, collapse or stenosis.

Peripheral Airway Disease: Bronchitis, Bronchiectasis,

Bronchiolitis, Bronchial Asthma.

Pulmonary Parenchymal Disease: Emphysema

In Obstructive Defects, the more severe the obstruction, the

greater the increase in residual volume and the more likely that

vital capacity will be decreased. Emphysema produces the greatest

degree of air trapping and the greatest reduction in FVC is seen.


In patients with obstructive defects, the forced VC may be less

than the slow VC

Obstructive Lung Disease: typically incr RV _ incr TLC & incr

RV/TLC ratio (20yo RV/TLC=25%; 80yo RV/TLC=43%... thus an elevated

ration above predicted for age identifies overinflation.)...Gas

dilution vs Body box.

** Emphysema (pink puffer) & Chronic Bronchitis (blue bloater)

* Restriction:

When decreased chest expansion is present, a Restrictive

Ventilatory Defect is present. It is reflected in a decrease in

TLC as reflected in decreased vital capacity (FVC) reflected in a

proportional decrease in FEV1 so that the ratio of FEV1/FVC remains

normal.

Interstitial: Interstitial pneumonitis(hypersensitivity), Fibrosis,

Pneumoconiosis, granulomatosis, Edema

Space Occupying Lesions: Tumors, cysts, Lobectomy, pneumonectomy


Pleural Disease: Pneumothorax, TB, Hemothorax, Pleural Effusion,

Empyema, Fibrothorax

Chest Wall Disease: Injury, Fx, Kyphoscoliosis (>100 degrees),

spondylitis (ankylosing Spond + Upper lobe cavitary disease w/

hemoptysis= Aspergillous fungus ball), Neuromuscular disease

(Myasthenia, Eaton Lambert, Musc Dyst, ALS, Guillain-Barre

Syndrome, Cervical Cord Syndrome, paralysis of a hemidiaphragm)

Extrathoracic Conditions: Obesity, Peritonitis, Ascites, Pregnancy.


Raw= change Pressure (P) / change Flow (Q)

If Q is normal and Raw high then pressure must be high suggesting

low compliance as with restriction.

Restrictive Lung disease: Obesity, Ascites, pregnancy...decr TLC

80% (IC usually remains unchanged).

In Restrictive disease the expiratory driving force is increased

although TLC and VC are decreased. The FEV1 is also relatively

increased due to an increase in driving force but since they are

functioning at a lower lung volume, it and the FVC will be

proportionately lower with an increased or normal ratio of

FEV1/FVC. The increased driving force in these defects is

mediated by a decreased compliance of the chest wall or parenchyma

causing increased elastic recoil.

On the other hand in emphysema, the expiratory driving force is

decreased by a decrease in elastic recoil and an increase in total

compliance ( eg. alveolar septal destruction and loss of

surfactant.) This accounts in part for the decrease in FEV1

observed as well as obstruction and the decrease in FVC from an

increased RV (eg. air trapping).

If flow (Q) is low and Raw is normal then pressure (P) must be low

and compliance high as in emphysema.

* Combined Obstructive and Restrictive ventilatory defects.

* FEV1/FVC in All

In obstructive defects the increase in Raw causes a proportionately

greater decrease in FEV1 than FVC so the ratio falls in obstruction

and is the most sensitive measure of it.

In Restriction, the increase in driving force causes a relative

increase in FEV1 although both FVC and FEV1 are lower than

predicted. Therefore, the ratio rises since FVC is lowered and

FEV1 increases.

In combined defects, the ratio usually falls...use the ratio of

FEF25-75%/FVC% and if >.8 = Restrictive; < .3 = Obstructive; & .5

- .8 = Combined

* Diseases

Asthma................Inc Raw (decr FEv1)...Bronchial edema,

bronchospasm, obstructive mucus.

Bronchitis............Inc Raw (decr FEV1)...Bronchial edema,

bronchospasm, mucus obstruction

Emphysema.............Inc Raw (decr FEV1)...loss of radial traction

on respiratory airways due to destruction of the alveolar sacs

Kyphoscoliosis........Dec Expand (decr FVC)...Increase in elastic

resistance of the chest wall due to abnormal curvature of the spine


Muscular Dystrophy....Dec Expand (decr FVC)...weakness of the

inspiratory muscles

Obesity...............Dec Expand (decr FVC)...increase in elastic

resistance of chest wall and abdomen due to adiposity

Pneumoconiosis........Dec Expand (decr FVC)...increase in elastic

resistance of the lungs due to fibrosis of the parenchyma

Pulm. Congestion: Both...Obstructive from bronchial edema and

compression of respiratory airways due to increased interstitial

and intravenous fluid pressure.....Restrictive from increase in

elastic resistance of lungs due to increase in interstitial /

intravenous pressure

Combinations..........Both

V. * What is normal

Static Lung Volumes:

* Input % lung volume...Closing volume and atelectasis and

regression equation for TLC.

TLC= .2 * Ht" - 7.33 +.0032 * Age +/- 1.61

Va = Ve(1 - Vd / Vt)

* TLC is 100%

VT between 40-50% of TLC and is 10%

FRC at 40% TLC

RV at 25% of TLC

Closing Volume is within ERV

* Dynamic Lung Volumes:

The normal population range includes 2 standard deviations above

and below the mean...Extrapolated to +/- 20% of mean as an accepted

latitude

Exception with FEF 25-75%....

Intermountain Criteria using confidence intervals.

Multiple different standards by different investigators using

varying types of populations. The only truly normal for someone

is their own baseline and use them as a control.

Ethnic differences (eg. Blacks and Asians subtract 10% from normal

values). Asians & Blacks have a 10% reduction in predicted

normals for volume, flow rates and diffusing capacity

Children also have different normals.

Men vs Women / age, height & weight (??obesity on VC)

In a computerized system it is important to know which set of

normals is used and be able to reconfigure and customise to the

situation.

A patient may be statistically normal by accepted nomograms but be

abnormal compared to himself. For example, his baseline may be

100% predicted and on repeat he may be 80%; both "normal" but

obviously a significant change. People have looked at FVC, FEV1

and FEF 25-75% to determine what are statistically significant

changes over a period of days and weeks, etc....

FEV1/FVC: Normal Low High

young 75-85 < 75 > 85

older 65-75 < 65 > 75

Severity:

FVC/FEV1/MVV FEF25-75%

Mild 65-85% 60-75%

Moderate 50-64% 45-69%

Severe 35-49% 30-44%

Very severe < 30-35%


FEF 25-75% %pred Obstructive Combined Restrictive

---------------- : < .3 .5 - .8 > .8

FVC % pred


Asthma and Bronchitis are potentially reversible (to some degree)

while emphysema with destruction of alveoli is not. All three are

combined to varying degrees eg COPD ????...There is acute and

chronic reversibility; the former being bronchospasm directly, the

latter being inflammation, secretions, infections, and bronchial

edema. The rule of 20% (FEF25-75% = 25%).

Morris JF, et al. Spirometric Standards for Healthy Nonsmoking

Adults. Am Rev Respir Dis 103:57, 1971

Goldman HI, Becklake MR. Respiratory Function Tests. Normal Values

at Medium Altitudes and the Prediction of Normal Results. Am Rev

Tuberc 79: 457, 1959

Changes FVC FEV1 FEF25-75%

-Daily

Normal 5% 5% 13%

Obstruct 11% 13% 23%

-Weekly

Normal 11% 12% 21%

Obstruct 21% 23% 30%

PaO2 >= .9 * (104.2-.27*Age) Normoxemia

A - aDO2 <= 1.1 * (2.5 + .21 * Age)

Ve= 5-7 L/min (_ with large dead space ventilation, hypoxia,

hypercarbia, acidosis, and anxiety..._ severe airway obstruction,

hypocarbia, alkalosis, and respiratory center depression by drugs

etc eg w/ nor A-a gradient)

Vt= 5-8 cc/kg

RR = 12 / min

DLco nor = 21 cc/min/mm Hg

-Decreased in emphysema, Fibrosis, Sarcoid, Pneumoconiosis, O2 Tox,

Pulm Edema

-R/o Anemia, Carboxymethemoglobinemia

-R/o Causes which Increase DLco

Raw < 2 cm H2O/L/sec

SC= (1/Raw)/TGV (thoracic Gas volume) nor= .14-.35

VI. Spirographic Patterns

* Static and * Dynamic

ATPS: Ambient Temperature and Pressure fully Saturated with water

vapor (760 +/- 20 mm Hg)

BTPS: Body Temperature and Pressure fully saturated with water

vapor ( @ 23 +/- 2 degrees C) if temperature is different, a

different factor must be used to correct ATPS to BTPS.

Specific Volume/Time ***...Flow/Volume****

* Upper Airway Obstruction:

From hypopharynx to intrathoracic trachea...glottic, subglottic,

tracheal stenosis; tracheomalacia; intraluminal or extraluminal

mass; Obstructive Sleep apnea...Fixed, Variable Intrathoracic, and

Variable Extrathoracic...With Fixed, changes in airway pressure do

not affect airway caliber therefore a squared off pattern...


With Extrathoracic, there is a negative intraluminal pressure

with inspiration and a positive with expiration distal to the

obstruction...The trachea may collapse during inspiration.

With an intrathoracic obstruction distal lumenal pressure is

positive during inspiration being dominated by the negative

intrapleural dilating force and collapses during expiration due to

positive surrounding pressure leading to expiratory collapse.

Upper Airway Obstruction

-FEF50% / FIF50% > 1 (extrathoracic)

-FEV1 (cc) / PEFR (L/m) >= 10 cc/L/min

-FIF 50% <= 100 cc/min

-FEV1 / FEV.5 >= 1.5

Air Trapping:


FRC plethys

----------- >= 1.10

FRC He


FRC plthys - FRC He > 200 cc

RV/TLC > 120% predicted

SVC - FVC >= 200 cc


* Maximum Voluntary Ventilation (MVV)

-Maximum volume that can be breathed per minute by voluntary effort

(41* FEV1=MVV

+/- 20%...effort???...the assumption is that the patient could

perform 40 of these manuevers per minute!!)...Large standard

deviation in populations. The computer calculates the MVV for us

if we don't perform it.

Actually performed over 10 seconds of rapid ventilation as deeply

as possible...watch for vertigo etc... After a full inspiration,

breath out into the machine which elevates the stylus to the mid

position and from there perform the maneuver...

Minute ventilation ...MVV...Alveolar Ventilation...Dead Space

Ventilation

MVV is based on overall level of energy/ eg lifestyle, nutrition

or other diseases...level of motivation, work of breathing,

fatigue...

-MVV is sustainable for only 15 - 30 seconds, whereas 75% MVV can be

sustained for about 4 minutes and 60% MVV can be sustained for 15 minutes

ENDURANCE TIME.



Decreased Maximal Inspiratory Force (MIF)

also FEF 200-1200 Decreased

also decreased PEFR


A. Neuromuscular Disorder

-Myasthenia Gravis

-Guillain Barre

-Poliomyelitis

-High Cervical Trauma

B. Poor Effort

-Debility

-Weakness

-Malingering

-Lack of Cooperation

C. Extrathoracic Airway Obstruction

-Substernal Thyroid

-Tracheal Stenosis

-Tracheomalacia

-Laryngeal Paralysis




Criteria for Poor Effort


FVC < SVC (vs Air Trapping)

FVC < 6-7 sec

PEFR is not sharp or rapid

MVV < 41 x FEV1 +/- 20%

w/ norm FEF 200-1200

MIFR decreased (vs impairment)



VII. * Exercise Testing

Exercise especially in cool air with rewarming causes wheezing in

many asthmatics. Exercise the person outside until AR >= 170 or

80% of predicted maximum...A decrease of 10% or more of baseline

is considered significant from FEV1/PEFR and usually follows

exercise with peak bronchospasm 3-7 minutes after done

(rewarming)...Simple and safe but Dr. present at all times... MDI

with beta2 agent...Injectable Epi/Terbutaline available...If

baseline PFT is abn or is wheezing at rest do not do exercise

study.

VII. * Methacholine Inhalation Challenge

-To Assess the presence of Bronchial Hyperreactivity by measuring

the response in FEV1, FVC, Raw, TGV and PEFR to Bronchoprovocative

Drug (Methacholine)

-Spirometer

-Bard-Parker Moduflex Aerosol Nebulizer Set

-3cc's Methacholine, 25 mg/cc

-Source of pressurized oxygen

-Isuprel Mistometer

-one amp of 1:1000 aq Epi

-Baseline Spirometry+

-If Baseline is Abn do not perform the test (the FEF 25-75% may be

abn and still do the test)

-Place 3cc sterile saline in Neb

-Noseclips in place

-5 deep breaths, after 5 min repeat spirometry...if FEV1 has decr

by >= 20% stop the test

-Next empty Neb and put 3 cc Methacholine

(25mg/cc)...Noseclips...One deep breath...wait 5 min and

spirometry; if >= 20% decr FEV1 stop = asthma

-Take 4 more deep breaths...after 5 min repeat...stop...>=20% decr

@ this point = asthma

IX. * DLco

Increased DLco..Kco ( > 140% pred)

1. Lung Compression:

-Scoliosis

-Obesity

-PEctus Excavatum

2. High Airways Resistance

-Asthma

-Cystic Fibrosis

-Central Airway Obstruction

3. Pulmonary Vascular Congestion

-CHF

-Regurgitant Valves

4. Intrapulmonary Hemmorhage

-Pulmonary Hemosiderosis

-Goodpasteur's

-Hemothorax

-etc

5. Physiologic Leak

-Tympanic rupture

-Tracheoesophageal fistula

-BPF



Decreased DLCO


Normal DLCO/VA Decreased DLCO/VA


1. Poor distribution of Ventilation 3. Enlarged alveolar spaces w/

2. Loss of functioning alveoli or lung reduced gas exchange (EMPHYSEMA)

units (lung resection, fibrosis, 4. Decreased RBC / Hb Contact

scarring) eg. should be corrected (ANEMIA HEMOGLOBINOPATHY)

for by volume 5. Loss of Capillary Bed

(PE VASCULITIS)

6. Filling of Alveoli or thicken-

X. Closing Volume of alveolar capillary membrane

(FIBROSIS INFLAMMATION EDEMA)

XII. Isovolume pressure flow curves





Delta Pressure (P)

Airway Resistance (Raw) = ---------------------

Flow (Q)

-cmH2O/L/sec

-If Flow (Q) is normal (eg normal FEV1, FVC, FEF) but Raw is INCREASED must

indicate DECREASED Compliance of the Lung reflected by an INCREASED

Pressure change.

-If Q is decreased and Raw is Normal than INCREASED LUNG COMPLIANCE must be

present with a DECREASED Pressure Change (as in emphysema)


delta VOLUME

Compliance (C) = ---------------- L/cmH2O Cdyn; Cstat

delta PRESSURE


delta PRESSURE

Elastance = ------------------ cmH2O/L

delta VOLUME


FLOW

Conductance = -------- L/sec/cmH2O

PRESSURE




Maximal Respiratory Pressures (Normal Values)


9-18 19-49 50-69 >=70

Males

PI max -96 +/- 35 -127 +/- 28 -112 +/- 20 -76 +/- 27

PE max 170 +/- 32 216 +/- 45 196 +/- 45 133 +/- 42

Females

PI max -90 +/- 25 -91 +/- 25 -77 +/- 18 -66 +/- 18

PE max 136 +/- 34 138 +/- 39 124 +/- 37 108 +/- 28




Respiratory Muscles & Their Innervations


Inspiratory

Sternocleidomastoid XI, C1, C2

Diaphragm C3, C4, C5

External Intercostals T1 - T12

Expiratory

Inspir Intercostals T1 - T12

Adbominals T7 - L1




The human diaphragm contains 3 types of muscle fibers.

-Slow Twitch Oxidative Fibers (SO):

-comprise 1/2 adult diaphragm

-Type I

-High Endurance with high myoglobin, Oxidative enzymes,

& Mitochondria

-With Mild Effort first recruited

-Fast-Twitch Oxidative Glycolytic Fibers (FOG)

-1/4 of Diaphragm

-Type IIA

-With Increasing Effort Recruited

-Fast-Twitch Glycolytic Fibers (FG)

-1/4 of Diaphragm

-With Intense Effort

-Type IIB

-These are Stronger Fibers with poor endurance


The fact that Maximal Sustainable Effort (MSV) is below the MVV is attributed

to early fatigue of FOG fibers.


There is High Frequency Fatigue (50 to 100 Hz stimulation) &

Low Frequency Fatigue (10-40 Hz).

Email to Warren S. Goff, D.O.,P.A.,FCCP.