Medicine Notes

7/29/2019 Medicine Notes

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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.

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