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Respiratory system:
Restrictive diseases have all reduced
volumes and capacities. Decreased FEV1,
dec FVC, FEV1/FVC normal or high.
Vital capacity is max inspiration followed by
max expiration.
Problem in restrictive disease involvesinhaling.
VC is reduced in obstructive diseases, as
you can max inhale but cannot max exhale.
Decrease FEV1( forced expiratory volumein 1 sec). FEV1/FVC is decreased in
obstructive diseases. Therefore, RV
increases. TLC increases in obstructive
diseases.
Obstructive disease have problem with
getting air out of lungs. eg. Emphysema
and Chronic Bronchitis(COPD). Increase in
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AP diameter of chest(barrel chest).
FEV 25-75%(mid max expiratory flow) is
used to differentiate obstructive and
restrictive. It is reduced in pt with
obstructive disease.
Residual volume inc in obstructive and dec
in restrictive(as all volumes dec inrestrictive diseases).
In diseases of alveolar capillary
membrane(e.g.. Adult respiratory distress
syndrome, Emphysema) dec oxygen, incCO2 leading to acidosis.
DLCO(diffusion of lung carbon monoxide) if
it is dec think of Emphysema. In chronic
bronchitis, alveolar membrane is intact.
Simple way to measure gas exchange at
alveolar capillary membrane is by Aleolar-
arterial(A-a) O2 gradient.
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Send ABGs, find value of PH,
PCO2,PO2(80mmHg)
Alveolar O2 @ room temp = 150-1.2(PC02)
eg. pco2=40 Therefore, Alveolar O2=102
For A-a. 102-80= 18. Normal A-a is 5-
15mmHg.
Solitary Pulmonary nodule. Is a nodule less
than 6cm on CXR. If greater than 6cm, it is
a pulmonary mass. If nodule is found in
young, non smoker and less than 6cm,repeat cxr 3 months/2yr. if no change it is a
benign lesion.
Types of calcification in a pulmonary
nodule. PET scan is more sensitive to pick
calcification in a nodule than CXR.
pop-corn calcification: in
Hemartomas( mixed epithelial cell tumor)
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central calcification or Bull's eye:
granulomas(TB)
eccentric calcification: Malignacy( go for
biopsy).
If pt is older and smoker and you find a
solitary nodule go for biopsy.
Pleural Effusion: costophrenic angle is
obliterated. Earliest sign in Pleural Effusion.
Approx 300cc fluid is required to obliterate
costophrenic angle. If you find obliteratedangle on CXR, do decubitus CXR( on lying
down on side of effusion). Fluid will move to
dependant part of lung. Go for
Thoracocentesis. More the effusion, safer is
the thoracocentesis. if no fluid and you put
a needle in it. it will cause pneumthorax.
Look for LDH( normal 200) and pleural
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proteins to classify effusions.
Classify all pleural effusion based on
whether they are Transudate or Exudate.
Transudate caused by system diseases.
Eg. Congestive Heart Failure due to inc
pressure. or dec oncotic pressure(e.g.,
nephrosis, cirrhosis). dec LDH, dec proteinsin both pleural fluid and serum.
Exudate is caused by pulmonary diseases
in which pleura becomes leaky like CA, TB
and pulmonary embolus( transudate orexudate), pneumonia, infections.
If pleural fluid becomes
infectious(complicated) you need to drain
effusion with chest tube to prevent scarring
of the lung. Signs of complicated pleural
fluid- dec ph(acidic), pus(empyema), gram
stain showing polymorph, dec glucose in
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fluid. e.g., para pneumonic effusion.
Atelectasis: collapse of part of lung. within
24-48hrs of post-op. caused by pain
medications and anaesthesia that would
impair cough reflex and poor inspiration.
Also due to non surgery related cases likeCA, Foreign body.
S/S: tachycadia, dyspnea. Tracheal
deviation toward the lesion. treatment.
Incentive spirometry.