Respiratory internal medicine

Respiratory Internal Medicine

Type I respiratory failure Type II Respiratory failure
Represents failure of oxygenation Represents a defect in ventilation
and is characterized by a low PaO2 (hypoventilation) and is
with normal or low PaCO2. characterized by decreased PaO2
PaO2 : Low (<60 mm Hg) with increased PaCO2.
PaCO2 : Normal or Low (≤49 mm PaO2 : Decreased (<60 mm Hg)
Hg) PaCO2 : Increased (>49 mm Hg)
PA-aO2 : Increased PA-aO2 : Normal
Causes: Causes:
This type is caused by conditions This type is caused by conditions
which affect oxygenation, like: causing hypoventilation as in :

 Parenchymal disease (V-Q  Obstructive lung disease: COPD,
mismatch) Foriegn.body
 Diseases of vasculature/shunts  Decreased central respiratory
Examples: drive e.g. CNS disorders like:-
- Pneumonia Brain injury, Meningitis
- ARDS  Weakness of respiratory muscles
- Emphysema e.g
- Right to left shunts - Peripheral N.S. disorders like:
M.gravis.
- Interstitial lung disease.
- MS disorders like
polymyositis.
- Rib cage disorders:
Kyphoscoliosis.

Type I respiratory failure Type II Respiratory failure
Hypoxemia with decreased PaCO2 Hypoxemia with increased PaCO2

Global institute of medical sciences


PRT Results Obstructive Pattern Restrictive Pattern
FEV1 Decreased (<80% predicted) Decreased (May be preserved)
(Decreased out of proportion to (Decreased in proportion to
FVC) FVC)
FVC Decreased (may by preserved) Decreased ((<80% predicted)
FEV1/FVC Decreased (<0.7) Normal or increased (>0.7)
(FEV1%)
FEF25-75 <50% predicted Decreased in proportion to loss
of lung volume
TLC Normal or elevated Decreased
DLCO Normal Decreased in intrinsic restrictive
Decreased in Emphysema lung disease.
Normal in neuromuscular or
musculoskeletal restrictive
disease.

Respiratory disease

Obstructive Restrictive
1. asthma
2. COPD – Chronic
bronchitis Parenchymal Extra parenchymal
Emphysema - sarcoidosis 1. Neuromuscular
3. Bronchiectasis - pneumoconiosis disease
4. Cystic fibrosis - idiopathic pulmonary - Diaphragmatic palsy
fibrosis - GB syndrome
5. Bronchiolitis
- drug/Radiation - Muscular dystrophy
induced interstitial - Cervical spine injury
lung disease. 2. Cest wall
- Kphoscoliosis
- Oesity
- Akylosing spondylitis



Obstructive lung disease Restrictive lung disease
Total lung capacity Normal to increase Decrease
Residual volume Increase Decrease
Vital capacity Decrease Decrease
FEV1/FVC Decrease (<0.7) Normal to increase (>0.7)
FEF 25-75% Decrease Normal
(forced expiratory flow
rate)
Diffusion capacity Normal (decrease in Decreased
emphysema)

FVC
The forced vital capacity (FVC) represents the total volume of gas exhaled with
maximum expiration following maximal inspiration. A reduced FVC suggests
pulmonary restriction.
FEV1% or FEV1/FVC
Note that FEV1 expressed as a percentage is actually FEV1/FVC.
The volume of gas exhaled during the first second while expiration from FVC is FEC1.
FEV1 is often represented as a ration of the FVC (often referred to as FEV1% rather than
FEV1/FVC)
Normal to increased FEV1% (FEV1/FVC) suggest restrictive lung disease
Decreased FEV1% (FEV1/FVC) suggests obstructive lung disease.
DLCO : (Diffusion capacity for carbon monoxide)
This reflects the ability of lungs to transfer gas across the alveolar – capillary interface.
Decreased DLCO is consistent with a diagnosis of:
 Interstitial lung disease
 Emphysema
 Pulmonary hypertension



Increased PaO2-PaO2
(alveolar arterial difference in oxygen)

Correctible with oxygen Not correctible with oxygen
V/Q Mismatch shunt
V/Q Mismatch: Shunt:
- Airway disease (Asthma, - Alveolar collapse
COPD) - Intra alveolar filling
- Interstitial lung disease 1. pneumonia
- Alveolar disease 2. pulm. Edema
- Pulmonary vascular disease - intracardiac shunt
- vascular shunt within lung

Decreased D LCO (diffusion capacity) Increased DLCO (diffusion capacity)
1. interstitial lung disease:- scarring 1. alveolar haemorrhage:- as a Good
of alveolar capillary units pasture‟s syndrome: haemoglobin
diminishes area of alveolar capillary contained in erythrocytes in
bed as well as pulmonary blood alveolar lumen binds Co so exhaled
volume carbon monoxide concentration is
2. emphysema:- alveolar walls are diminished & DLCO is increased.
destroyed so the surface area of 2. congestive heart failure:- may be
alveolar capillary bed is diminished elevated if pulmonary blood
3. recurrent pulmonary embolism volume is increased. Once
and primary pulmonary pulmonary edema ensues DLCO
hypertension:- disease causes a may decrease as and the net DLCO
decrease in cross sectional area and depends on the opposing influences.
volume of pulmonary vasculature



Asthma

Extrinsic asthma /allergic asthma Intrinsic asthma/Idiosyncratic
asthma
- History of atopy is present
- Attacks related to environmental - No history of atopy (concomitant
exposures nasal polyps are usually present
- IgE antibody levels are increased and patients may be aspirin
- Early onset of disease (young) sensitive)
- Usually is less severe, intermittent - Attacks not related to
asthma that may however progress environmental exposures: occur
to severe persistent asthma without provocation
- IgE antibody levels are normal
- Delayed onset of disease (adult
onset asthma)
- Usually have more severe
persistent asthma.

The microscopically identifiable features described in sputum are three ‘C’s
Charcot Leyden crystals : derived from granules of eosnophils and found only in asthma
Curshmann spirals : curiously twisted casts of airways : Whorls of shed epithelium
Creola bodies : clumps of cells or isolated metaplastic cells.

Hypoxia is the universal finding in Asthma
Hypocapnia and respiratory alkalosis is seen in most asthmatic patients
Hypercarbia and Respiratory acidosis are very late features of asthma and signify
severe obstruction and respiratory failure. These are not universal findings in Asthma.



Management of acute bronchial asthma:

Sit patient up and give high dose O2 (100%)

β2 agonist / Salbutamol (nebulized)

Alternate β2 agonist
Terbutaline
Fenoterol etc.

Steroids: hydrocortisone IV or Prednisolone orally

Additive treatment if life threatening features are present
1. anticholinergic : iprotropium bromide
2. methylxanthines : aminophyllines

Panacinar emphysema Centriacinar emphysema
- acini are uniformly involved - central or proximal parts of
from level of respiratory acini formed by respiratory
bronchiole to terminal blind bronchioles are affected
alveoli. whereas distal alveoli are
- Lsions are more common in spared
lower zone and bases - lesions are more severe and
- Occurs in association with common in Upper lobes
α1 antitrypsin deficiency - occurs predominantly in
smokers
- I the commonest pattern



Asbestos related lung disease

Pulmonary Pleural

Non malignant Malignant Non malignant Malignant
Diffuse Bronchogenic
interstitial - Pleural plaques - Mesothelioma
carcinoma - Diffuse pleural Both plerural
fibrosis
All histological thickening and peritoneal
(asbestosis)
subtypes of - Acute benign mesotheliomas
Asbestosis is
lung cancer pleural effusion develop in
defined as a
occur with - Rounded persons
diffuse interstial
increased atelectasis exposed to
fibrosing disease
frequency but asbestos
of lung caused by
adenocarcino
exposure to
ma has the
asbestos fibres.
highest
incidence

Silicosis has predilection for upper lobes
Radiographs typically show fine nodularity in the upper zones of the lung
Rounded opacities appear in the upper lobes on chest radiograph
Silicosis is associated with calcific Hilar adenopathy
Calcification of hilar lymph nodes may occur in as many as 20% oc cases and produce a
charachteristic “egg shell” pattern.
Silicosis is associated with tuberculosis
Because silica is cytotoxic to alveolar macrophages, patients with silicosis are at greater
risk of acquiring lung infections that involve these cells as a primary defense including
myocobacterium tuberculosis, atypical mycobacteria and fungi



Clinical spectrum of pulmonary aspergillosis

saprophytic infection invasive aspergillosis Allergic aspergillosis

aspergilloma (fungal - Invasive bronchial
ball) - Allergic bronchial
aspergillosis (IBA) asthma
- Chronic pulmonary - Allergic
aspergillosis (CPA) bronchopulmonary
- Invasive pulmonary aspergillosis(ABPA)
aspergillosis (IPA) - Extrinsic allergic
alveolitis (type to
hypersensitivity
pneumonitis)

kleibsella pneumonia

kleibsella pneumonia presents as a typical ‘air space’ pneumonia with
cough productive of purulent sputum. ‘purulent sputum production and
„air space‟ diseases X ray are typical‟
causes of atypical pneumonias:
1. mycoplasma pneumonias
2. viral pneumonias
- influenza
- RSV
- Adenovirus
- Rhinovirus
- Rubeola
- Varicilla
- Corona virus
3. Chlamydia pneumonia
4. coxiella burnetti
5. pneumocystis carinii


Crona virus is an infrequent cause of pneumonia.

Pneumocytic carinni pneumonia is characterized by a prominent
eosinophilic exudates and mild interstitial pneumonitis. These is
damage to type I pneumocytes and associated compensatory
hypertrophy of type II pneumocytes.

Classic histopathology in pneumocystis pneumonia

Intra alveolar changes interstitial changes

Mild interstitial pneumonitis
Prominent eosinophilic foamy, vacuolated
- Mononuclear interstitial cell
intra alveolar exudeate (HE staining)
infiltrate (mild)
- Intra alveolar exudates contains the
- Damaged type I pneumocytes
organisms, which can be identified in
- Hypertrophy / proliferation of type
various stages of development
II pneumocytis (reparative
(throphozoite and cystic stage) by the
response)
use of special stains such as
pneumocystis attaches to and
1. methamine silver / Toluidine stain
damages type 1 pneumocytes.
2. wright giemsa stain
There is associated
3. papanicolaou’s stain
compensatory hypertrophy of
type II pneumocytes.



Montoux test
Montoux test is carried out by injecting one tuberculin unit (1TU) of PPD in 0.1 ml
on the flexor surgace of forearm (PPD RT 23 with Tween 80)

Test is read after 72 hrs (not 48 hrs)

look for erythema and
induration

<6 mm 6-9 mm >10 mm
negative doubtful Positive

- a positive test indicates that patient is infected with M. tuberculosis. It
does not however prove that the person is ‘suffering’ from the disease
- studies indicate that 92% of new cases occur in persons who already
are tuberculin reactors
- 6-9 mm induration does not indicate high chances of developin
tuberculosis. Infact patients with 25 mm induration have more chances of
developing tuberculosis than those with 6-9 mm induration.



Sarcoidosis
Sarcoidosis is a chronic multisystem disorder of unknown causes characterized by
accumulation of T lymphocytes and mononuclear phagocytes in various tissues of body

Non caseating SARcoid granulomas in affected organs

Lung (90%) lymphnodes skin Others
(75-90%)
-Eye :- uveitis
- interstitial - Erythema
- B/L hilar - Kidney (rare):-
lung disease. nodosum
Lymphadenopathy renal
. fibrosis of lung - Lupus hypercalcemia
is the hallmark of perenium
parenchyma sarcoidosis with or without
- Pleura is (purple blue hypercalcuria
- Parotid shiny
involved in 5% of enlargement B/e - Skeletal :-
cases u/e swollen arthritis
involvement is the lesions on
pleural effusion vuli - Nervous
- Cavitation is nose,
system:-
rare cheeks, lips, peripheral
ears). neuropathy
- Heart :- cor
pulmonle

Inclusions seen in giant cells in sarcoidosis (remember as SARcoidosis)
- Schaumann bodies
- Asteroid bodies
- Residual bodies



Pneumothorax

traumatic
Spontaneous pneumothorax pneumothorax (non
spontaneous
pneumothorax)
-These
Primary spontaneous Secondary spontaneous penumothoraces occur
pneumothorax pneumothorax as a result of :
1. blunt trauma or
- Occur in persons with No • occurs in persons 2. penetrating trauma
clinical evidence of lung with an underlying - Iatrogenic
disease and without lung disease as a pneumothorax is
precipitating event. complicationof the subcategory of
- Most of these patients have underlying disease traumatic
occult lung disease (sub process pneumothorax
clinical) with subpleural blebs Causes of iatrogenic
on CT scan Etiology of pneumothorax
characterstics of affected
secondary - Thoracocentesis
people are :-
- tall, thin, males pneumothorax - Insertion of central
- smokers venous catheter
- Mechanical
- subpleural blebs on lungs
ventilation (IPPV,
assisted ventilation etc)
- Surgery

Obstructive lung disease
Malignancy
Interstitial lung disease
Connective tissue
Infection disease



Facts to remember

Most frequent histological type Adenocarcinoma

Most frequent histological type in India Squamous cell
carcinoma
Most common histological varieny in life time non-smokers Adenocarcinoma

Most common histological variety in young patients Adenocarcinoma

Most common histological variety in females Adenocarcinoma

Most common site for metastasis from Ca lung Liver

Most common endocrine organ to be involved by metastasis Adrenals
from Ca lung

Ca lung which metastizes to opposite lung Adenocarcinoma

Commonest tumor to metastise to heart Ca lung (Bronchognic
Ca)
Histological varieties that cavitate Squamous cell and
large cell
Histological varieties that are central in distribution Squamous cell and
small cell
Histological varieties that are peripheral in distribution Adenocarcinoma

Pancoost tumor is histologically Squamous cell
Most common variety associated with paraneoplatic syndrome Small cell variety
Most common variety associated with hypokalemia Small cell (presumably
d/t ACTH)
Most common variety associated with hypercalcemia Squamous cell
(presumably d/t PTH)
Histological variety most responsive to chemotherapy Small cell

Histological variety response to radiotherapy Small cell


Histological variety associated with hest prognosis Squamous cell

The most common malignancy of lung is adenocarcinoma (overall/world wide):-

Most common lung cancer worldwide is Adenocarcinoma
Most common lung cancer in India is swquammous cell carcinoma
Most common lung cancer in women is adenocarcinoma
Most common lung cancer in smokers is squammous cell carcinoma
Most common lung cancer in nonsmokers is adenocarcinoma
Most common lung cancer in young patients is adenocarcinoma
Most common lung cancer to metastasize is small cell carcinoma.

Ectopic hormones produced by small cell Paraneoplastic syndrome
carcinomas
- ACTH Cushings syndrome
- SIADH/ANP Hyponatremia
- Calcitonin Hypocalcemia
- Gonadotropins gynaecomastia


Respiratory internal medicine

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