RESPIRATORY PATHOLOGY

Normal Lung Function: exchange of gases between inspired air and blood Right lung - 3 lobes Left lung- 2 lobes Double arterial supply to lungs (pulmonary and bronchial arteries)

The major function of the lung is to excrete carbon dioxide from blood and replenish oxygen. Trachea ↓ Principal Bronchi ↓ Bronchi ↓ Bronchiole ↓ Terminal Bronchiole ↓ Respiratory Bronchiole ↓ Alveoli

– Acinus is the functional unit of lung whereas alveoli are the chief sites of gaseous exchange. – Lobule is composed of 3-5 terminal bronchioles with their acini. – Alveoli are lined by type I pneumocytes (forming 95% of alveolar surface) and type II pneumocytes (responsible for secretion of surfactant and repair of alveoli after type I pneumocyte destruction). The alveoli wall has the presemce of pores of KohnQ for allowing the passage of bacteria and exudate between adjacent alveoli.

The entire respiratory tract is lined by pseudostratified, tall, columnar ciliated epithelial cells except vocal cords (these have stratified squamous epithelium. Bronchioles do not have cartilage and submucosal glands in wall like bronchi. Terminal bronchiole contain maximum smooth muscle relative to the wall thickness..

This bronchus has a surrounding ring of cartilage (hyaline) plus sub-mucus glands (upper right).

This is normal lung microscopically. The alveolar walls are thin and delicate. The alveoli are well-aerated and contain only an occasional pulmonary macrophage (type II pneumonocyte).

Microscopic structure of the alveolar wall. Note that the basement membrane (yellow) is thin on one side and widened where it is continuous with the interstitial space. Portions of interstitial cells are shown.

Clinical signs symptoms of lung Cough Dyspnea Cyanosis Chest pain Hemoptysis

Physical examination of the chest Inspection Movements-symmetry Accessory muscle of respiration Palpation Percussion Auscultation

Tachpnea Chest palpation Trachea position Tactile vocal fremitus Percussion Dullness Hyper resonant

Auscultation Normal vesicular breath sounds Brobchial breathing Added sounds/adventitious sounds Crackles Wheeze Rhonchi Inspiratory stridor Pleural friction rub Grunting

Investigations: Sputum,and Pleural fluid Microbes; culture and sensitivity malignant cells FNAC CT guided biopsy Pleural biopsy/Pleural tap

Imaging Chest X- ray CT scan MRI Bronchography Arteriography

Investigations Bronchoscopy: - visualize, - cytology - biopsy - broncho alveolar lavage

Investigations Ventilation scan Perfusion scan V/Q ratio-

Tests of pulmonary function Arterial blood gases pCO 2, pO 2 Spirometry - Ventilatory function - Total Lung Capacity - Vital Capacity – Residual Volume

Tests of pulmonary function Forced Vital Capacity - FVC Forced Expiratory Volume - FEV1 FEV1 : FVC ratio (normal > 75%)

General Categories Congenital Anomalies Atelectasis Pulmonary Vascular Disorders Pulmonary Infections Obstructive and Restrictive Diseases Pulmonary Tumors Diseases of the Pleura

Atelectasis Definition- incomplete expansion of the lung or collapse of the previously inflated lung, leading to airless pulmonary parenchyma. Types Acquired –Resorption or Obstruction – Compression – Contraction And patchy atelectasis

Resorption atelectasis occurs when an obstruction prevents air from reaching distal airways. The air already present gradually becomes absorbed,and alveolar collapse follows. Depending on the level of airway obstruction, an entire lung, a complete lobe, or one or more segments may be involved. The most common cause of resorption collapse is obstruction of a bronchus by a mucous or mucopurulent plug. postoperatively bronchial asthma, bronchiectasis, chronic bronchitis, tumor, or foreign body aspiration, particularly in children.

Compression atelectasis. called passive or relaxation atelectasis) is usually associated with accumulation of fluid, blood, or air within the pleural cavity, which mechanically collapses the adjacent lung. pleural effusion, caused most commonly by congestive heart failure (CHF). Leakage of air into the pleural cavity (pneumothorax) also leads to compression atelectasis. Basal atelectasis resulting from the elevated position of the diaphragm commonly occurs in bedridden patients, in patients with ascites, and during and after surgery.

Patchy atelectasis due to surfactant deficiency Hyaline membrane disease And Adult respiratory distress syndrome

Contraction atelectasis Contraction (or cicatrization) atelectasis occurs when either local or generalized fibrotic changes in the lung or pleura hamper expansion and increase elastic recoil during expiration. Contraction atelectasis is irreversible. The other types of atelectasis are Reversible.

A 16-year-old boy is rushed to the emergency room after sustaining a stab wound to the chest during a fi ght. Physical examination reveals a 1-cm entry wound at the right 5 th intercostal space in the midclavicular line. His temperature is 37°C (98.6°F), respirations are 35 per minute, and blood pressure is 90/50 mm Hg. A chest X-ray shows air in the right pleural space. Which of the following pulmonary conditions is the expected complication of pneumothorax arising in this patient? (A) Atelectasis (B) Chylothorax (C) Diffuse alveolar damage (D) Empyema (E) Pyothorax