PHARMACOTHERAPY - I PHCY 310 University of Nizwa College of Pharmacy and Nursing School of Pharmacy PHARMACOTHERAPY - I PHCY 310 Lecture 7 Respiratory Disorders “Pulmonary Function Tests” Dr. Sabin Thomas, M. Pharm. Ph. D. Assistant Professor in Pharmacy Practice School of Pharmacy University of Nizwa

Anatomy and Physiology of Lungs Left and right lungs are in the pleural cavity of the thorax. Right lung has three lobes, but the left has only two lobes; space is thus provided for the heart. Lungs are connected to pharynx by trachea. Trachea splits into left and right main stem bronchi that deliver inspired air to respective lungs.

Main bronchi split into smaller bronchi, bronchioles, terminal bronchioles and finally alveoli. In alveoli, the lungs exchange carbon dioxide for oxygen across a thin membrane separating capillary blood from inspired air. Thoracic cavity is separated from abdominal cavity by diaphragm-a thin sheet of dome shaped muscles-contracts and relax during breathing.

Lungs are contained within the rib cage but rest on the diaphragm. Between the ribs are two sets of intercostal muscles-attach to each upper and lower rib. During inhalation, the intercostal muscles and diaphragm contracts, thereby enlarging the thoracic cavity. This generates a negative intrathoracic pressure, allowing air to rush in through nose and mouth down into pharynx, trachea and lungs. Purpose of lungs is to take oxygen from the atmosphere and exchange it for CO2 in blood.

Spirogram

Introduction Pulmonary Function Tests (PFTs) are useful - in diagnosing respiratory disorders. - to monitor therapy for patients with respiratory diseases.

Introduction Clinical uses of PFTs: Evaluate respiratory symptoms Screen for respiratory diseases Assess disease severity Monitor the cause of disease Evaluate the response to therapy Assess the risk of pulmonary exposure to environmental toxins

1. Forced expiratory volume (FEV1) using spirometer. Invistigations: 1. Forced expiratory volume (FEV1) using spirometer. 2. Forced vital capacity (FVC) using spirometer. 3. FEV1/FVC: it should be ≥ 75% for proper lung performance. 4. Peak expiratory flow rate (PEFR) using peak flow meter. FEV1: the forced expiratory volume in 1st second of exhalation (after maximum inspiration). FVC: the forced expiratory volume after maximum inspiration. spirometer

PEFR (self assessment): This is the speed of the air moving out of patient’s lungs at the beginning of the expiration, measured in liters per second.

Reversibility A significant reversibility is defined as an improvement of 12% and200 ml in FEV1 15 to 20 minutes post inhaled short acting β2 agonist. A lack of response to bronchodilator testing in the laboratory does not preclude a clinical response to bronchodilator therapy (ATS/ERS task force Euro Resp J 2005) A lack reversibility cannot asses the bronchoprotective property of medication