pulmonary function tests pt cardooo3.pdf

PT for Cardiovascular Pulmonary Disease and Surgery (4242) Dr: Magda M. Rashid Objectives : Lung volumes Air flow Ratios Flow volume curves Arterial blood gases Pulse oximeter Diffusing lung capacity(DLCO)  Pulmonary function tests: noninvasive tests that show how well the lungs are...

PT for Cardiovascular Pulmonary Disease and Surgery (4242) Dr: Magda M. Rashid Objectives : Lung volumes Air flow Ratios Flow volume curves Arterial blood gases Pulse oximeter Diffusing lung capacity(DLCO)  Pulmonary function tests: noninvasive tests that show how well the lungs are working.PFTs are designed for assessment of airway and parenchymal diseases of lungs through measurement of lung volumes and capacities. Indications of pulmonary function test: To assess symptoms such as dyspnea To confirm a diagnosis based on history, physical examination, or imaging. To determine the extent of impairment of a known lung disease. To monitor disease course and response to therapy ,environmental pollutants, and occupational toxins. To establish prognosis and risk in patients with lung disease. To screen for early asymptomatic lung disease in hig risk populations. To assess risk of thoracic and extra-thoracic surgery. Lung volume and capacities: Lung volume and capacities are related to person’s age , weight , sex and body position and are altered by disease. A basic understanding of these measurements and what its values reflect, is useful for a therapist treating patients with pulmonary dysfunction. 1-Static respiratory volumes: Static lung volumes are determined by methods in which airflow velocity does not play a role. The parameters assessed are: 4-volumes 4- capacities  Tidal volume TV: Volume of air inhaled and exhaled during normal quiet breathing(500 ml). Inspiratory reserve volume IRV: Volume of air that can be forcefully inspired after a normal quiet inspiration(3100 ml). Expiratory reserve volume ERV :Volume of air that can be forcefully expired after a normal quiet expiration(1200ml). Residual volume RV : Volume of air remaining in the lungs after a forceful expiration (1200ml).  Vital Capacity (slow vital capacity) (SVC) Maximal amount of air that can be slowly exhaled after a maximal inspiration 4800 cc TV+IRV +ERV= VC Functional residual capacity FRC Volume of air remaining in the lungs after a normal quiet expiration 2400 cc ERV+RV=FVC Inspiratory capacity IC Maximal amount of air that can be inhaled after a normal exhalation 3600 c TV +IRV=IC Total lung capacity TLC maximum amount of air that can fill the lung ( Total volume of lungs) 6000 cc TV+IRV+ERV+RV=TLC 2-dynamic lung volumes: Spirometry is used to measure the rate at which the lung changes its volumes during forced breathing maneuvers. These include several parameters as: 1-Forced expiratory vital capacity (FVC) is Volume of air that can be forcefully , quickly and maximally exhaled after a maximal inhalation. the majority of FVC can b exhaled in < 3 second in normal people it is measured in liters L Forced expiratory volume FVC1: is maximum amount of air you can forcefully exhale in one second. Normal people can exhale more than 75-80 % of their FVC in the first second so FEV1/FVC ratio can be used to diagnose lung disease. 2-FEV1/FVC ratio :The amount of air exhaled in the 1st second as a fraction of the FVC. interpretation of pulmonary function test: The first step in interpretation is to identify the type of lung disease which is usually of two types: 1. Obstructive lung disease : Increased resistance to airflow due to partial or complete obstruction at any level of the airway leading to impairment of exhalation, e.g. bronchial asthma, emphysema. 2. Restrictive lung disease : When the lung tissue or chest wall (or both) cannot expand enough to accommodate the amount of air required by the patient, e.g. interstitial lung disease, idiopathic pulmonary fibrosis 3-Maximum Voluntary Ventilation (MVV): is the maximum volume of air that is moved in and out of the lungs by voluntary effort in 1 minute. –Instructed to breath as hard as possible for 12-15 seconds ,then extrapolated to 1 minute. -Significance:.Index for respiratory efficacy and physical fitness.Respiratory muscle assessment.pre-operative assessment -Normal: male :80-200L/min, female 60-160 L/min. Air flow: The peak expiratory flow (PEF)also Peak expiratory flow rate PEFR is a Person maximum speed of expiration, Measured with peak flow meter , as small, Hand held device used to monitor a person Ability to breath out air Arterial Blood Gases: Arterial blood gas (ABG) analysis is an essential part of diagnosing and managing a patient’s oxygenation status and acid–base balance ABG evaluate ❑ Acid base balance PH , PaCO2 ,HCO3 ❑Oxygenation status PaO2 ,SaO2 ❑Adequacy of ventilation PaCO2 Acid base balance: body cells need steady state between acids and base lungs and kidney excrete metabolic acids produced in the body, break down of this process leads to acid bases disorders the pH of the human body ranges between 7.35 to 7.45, with the average at 7.40. Why this number? A pH at this level is ideal for many biological processes Due to the importance of sustaining a pH level in the needed narrow range, the human body contains compensatory mechanisms to maintain it in its normal range CO2+H2O ↔ H2CO3 ↔ H++HCO3 The human body experiences four main types of acid-based disorders: metabolic acidosis metabolic alkalosis respiratory acidosis respiratory alkalosis. If one of these conditions occurs, the human body should induce a counterbalance in the form of an opposite condition. The most important normal values on an ABG: pH = 7.35 to 7.45 pH < 7.35 is an acidemia pH ˃ 7.45 is an alkalemia PCO2 = 35 to 45 mmHg partial pressure of carbon dioxide, dissolved gas in plasma. it is the respiratory component of acid base status HCO3 = 22 to 26 mEq/L the metabolic component of acid base status regulated by renal system as a compensatory response to changes in PCO2 oxygenation status : PaO2 partial pressure of oxygen ,dissolved gas in plasma normal value 80 -100 mmHg 60 -79 mild hypoxaemia 40-59 moderate hypoxaemia < 40 sever hypoxaemia SaO2 oxygen saturation percent of hemoglobin that is saturated with oxygen normal ˃95 % determined from pulse oximeter. Pulse oximeter non invasive ,painless, general indicator of oxygen delivery to the peripheral tissues (as finger, ear lobe or nose) interpretation of ABG: Look at the pH if pH < 7.35 = acidosis ,pH ˃ 7.45 is an alkalosis look at PaCO2 level which determines respiratory contribution, PaCO2 ˃ 45 = respiratory acidosis that means the respiratory system is lowering the pH. PaCO2< 35 = respiratory alkalosis that means the respiratory system is elevating the pH. HCO3- level determine metabolic/kidney effect. An elevated HCO3˃ 26 is raising the pH = metabolic alkalosis. and HCO3