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PULMONARY FUNCTION TESTS Dr. Pooja Chopra

PULMONARY FUNCTION TESTS Dr. Pooja Chopra. poojadeep_dreamsin@yahoo.co.in. PFT tracings have: Four Lung volumes : tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume

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PULMONARY FUNCTION TESTS Dr. Pooja Chopra

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  1. PULMONARY FUNCTION TESTSDr. Pooja Chopra poojadeep_dreamsin@yahoo.co.in www.anaesthesia.co.in

  2. PFT tracings have: Four Lung volumes: tidal volume, inspiratoryreserve volume, expiratory reserve volume, and residual volume Five capacities:, inspiratory capacity, expiratory capacity, vital capacity, functional residual capacity, and total lung capacity Lung Volumes and Capacities Addition of 2 or more volumes comprise a capacity. www.anaesthesia.co.in

  3. Tidal Volume (TV): volume of air inhaled or exhaled with each breath during quiet breathing (6-8 ml/kg) Inspiratory Reserve Volume (IRV): maximum volume of air inhaled from the end-inspiratory tidal position.(1900-3300ml) Expiratory Reserve Volume (ERV): maximum volume of air that can be exhaled from resting end-expiratory tidal position.( 700-1000ml). Lung Volumes www.anaesthesia.co.in

  4. Residual Volume (RV): Volume of air remaining in lungs after maximium exhalation (20-25 ml/kg) (1700-2100ml) Indirectly measured (FRC-ERV) It can not be measured by spirometry Lung Volumes www.anaesthesia.co.in

  5. Total Lung Capacity (TLC): Sum of all volume compartments or volume of air in lungs after maximum inspiration (4-6 L) Vital Capacity (VC): TLC minus RV or maximum volume of air exhaled from maximal inspiratorylevel. (60-70 ml/kg) (3100-4800ml) Inspiratory Capacity (IC): Sum of IRV and TV or the maximum volume of air that can be inhaled from the end-expiratory tidal position. (2400-3800ml). Expiratory Capacity (EC): TV+ ERV Lung Capacities www.anaesthesia.co.in

  6. Functional Residual Capacity (FRC): Sum of RV and ERV or the volume of air in the lungs at end-expiratory tidal position.(30-35 ml/kg) (2300-3300ml). Measured with multiple-breath closed-circuit helium dilution, multiple-breath open-circuit nitrogen washout, or body plethysmography. It can not be measured by spirometry) Lung Capacities (cont.) www.anaesthesia.co.in

  7. VOLUMES, CAPACITIES AND THEIR CLINICAL SIGNIFICANCE • TIDAL VOLUME (TV): • VOLUME OF AIR INHALED/EXHALED IN EACH BREATH DURING QUIET RESPIRATION. • N – 6-8 ml/kg. • TV FALLS WITH DECREASE IN COMPLIANCE, DECREASED VENTILATORY MUSCLE STRENGTH. • INSPIRATORY RESERVE VOLUME (IRV): • MAX. VOL. OF AIR WHICH CAN BE INSPIRED AFTER A NORMAL TIDAL INSPIRATION i.e. FROM END INSPIRATION PT. • N- 1900 ml- 3300 ml. www.anaesthesia.co.in

  8. CONTINUED……… 3) EXPIRATORY RESERVE VOLUME (ERV): • MAX. VOLUME OF AIR WHICH CAN BE EXPIRED AFTER A NORMAL TIDAL EXPIRATION i.e. FROM END EXPIRATION PT. • N- 700 ml – 1000 ml 4) INSPIRATORY CAPACITY (IC) : • MAX. VOL. OF AIR WHICH CAN BE INSPIRED AFTER A NORMAL TIDAL EXPIRATION. • IC = IRV + TV • N-2400 ml – 3800 ml. www.anaesthesia.co.in

  9. CONTINUED……….. 4)VITAL CAPACITY: COINED BY JOHN HUTCHINSON. • MAX. VOL. OF AIR EXPIRED AFTER A MAX. INSPIRATION . • MEASURED WITH VITALOGRAPH • VC= TV+ERV+IRV • N- 3.1-4.8L. OR 60-70 ml/kg • VC IS COSIDERED ABNORMAL IF ≤ 80% OF PREDICTED VALUE www.anaesthesia.co.in

  10. FACTORS INFLUENCING VC • PHYSIOLOGICAL : • physical dimensions- directly proportional to ht. • SEX – more in males : large chest size, more muscle power, more BSA. • AGE – decreases with increasing age • STRENGTH OF RESPIRATORY MUSCLES • POSTURE – decreases in supine position • PREGNANCY- unchanged or increases by 10% ( increase in AP diameter In pregnancy) www.anaesthesia.co.in

  11. CONTINUED……… • PATHOLOGICAL: • DISEASE OF RESPIRATORY MUSCLES • ABDOMINAL CONDITION : pain, dis. and splinting www.anaesthesia.co.in

  12. FACTORS DECREASING VITAL CAPACITY • Alteration in muscle power- d/t drugs, n-m dis., cerebral tumours. • Pulmonary diseases – pneumonia, chronic bronchitis, asthma, fibrosis, emphysema, pulmonary edema,. • Space occupying lesions in chest- tumours, pleural/pericardial effusion, kyphoscoliosis • Abdominal tumours, ascites. www.anaesthesia.co.in

  13. 5) Depression of respiration : opioids/ volatile agents 6) Abdominal splinting – abdominal binders, tight bandages, hip spica. 7)Abdominal pain – decreases by 50% & 75% in lower & upper abdominal Surgeries respectively. 8) Posture – by altering pulmonary Blood volume. www.anaesthesia.co.in

  14. DIFFERENT POSTURES AFFECTING VC • POSITION • TRENDELENBERG • LITHOTOMY • PRONE • RT. LATERAL • LT. LATERAL • DECREASE IN VC • 14.5% • 18% • 10% • 12% • 10% www.anaesthesia.co.in

  15. VC CONTINUED……. • VC correlates with capability for deep breathing and effective cough. • So in post operative period if VC falls below 3 times VC– artificial respiration is needed to maintain airway clear of secretions. www.anaesthesia.co.in

  16. CONTINUED……. 6) TOTAL LUNG CAPACITY : • Maximum volume of air attained in lungs after maximal inspiration. • N- 4-6 l or 80-100 ml/kg • TLC= VC + RV 7) RESIDUAL VOLUME (RV): • Volume of air remaining in the lungs after maximal expiration. • N- 1570 – 2100 ml OR 20 – 25 ml/kg. www.anaesthesia.co.in

  17. CONTINUED…… 8) FUNCTIONAL RESIDUAL CAPACITY (FRC): • Volume of air remaining in the lungs after normal tidal expiration, when there is no airflow. • N- 2.3 -3.3 L OR 30-35 ml/kg. • FRC = RV + ERV • Decreses under anaesthesia • with spontaneous Respiration – decreases by 20% • With paralysis – decreases by 16% www.anaesthesia.co.in

  18. FACTORS AFFECTING FRC • FRC INCREASES WITH • Increased height • Erect position (30% more than in supine) • Decreased lung recoil (e.g. emphysema) • FRC DECREASES WITH • Obesity • Muscle paralysis (especially in supine) • Supine position • Restrictive lung disease (e.g. fibrosis, Pregnancy) • Anaesthesia • FRC does NOT change with age. www.anaesthesia.co.in

  19. FUNCTIONS OF FRC • Oxygen store • Buffer for maintaining a steady arterial po2 • Partial inflation helps prevent atelectasis • Minimise the work of breathing • Minimise pulmonary vascular resistance • Minimised v/q mismatch - only if closing capacity is less than frc • Keep airway resistance low (but not minimal www.anaesthesia.co.in

  20. Pulmonary Function Tests • The term encompasses a wide variety of objective tests to assess lung function • Provide objective and standardized measurements for assessing the presence and severity of respiratory dysfunction. www.anaesthesia.co.in

  21. GOALS • To predict the presence of pulmonary dysfunction • To know the functional nature of disease (obstructive or restrictive. ) • To assess the severity of disease • To assess the progression of disease • To assess the response to treatment • To identify patients at increased risk of morbidity and mortality, undergoing pulmonary resection. www.anaesthesia.co.in

  22. GOALS, CONTINUED…….. • To wean patient from ventilator in icu. • Medicolegal- to assess lung impairment as a result of occupational hazard. • Epidemiological surveys- to assess the hazards to document incidence of disease • To identify patients at perioperative risk of pulmonary complications www.anaesthesia.co.in

  23. INDICATIONS OF PFT IN PAC TISI GUIDELINES FOR PREOPERATIVE SPIROMETRY • Age > 70 yrs. • Morbid obesity • Thoracic surgery • Upper abdominal surgery • Smoking history and cough • Any pulomonary disease www.anaesthesia.co.in

  24. INDICATIONS FOR PREOPERATIVE SPIROMETRY • ACP GUIDELINES FOR PREOPERATIVE SPIROMETRY • Lung resection • H/o smoking, dyspnoea • Cardiac surgery • Upper abdominal surgery • Lower abdominal surgery • Uncharacterized pulmonary disease(defined as history of pulmonary Disease or symptoms and no PFT in last 60 days) www.anaesthesia.co.in

  25. BED SIDE PFT • Sabrasez breath holding test: • Ask the patient to take a full but not too deep breath & hold it as long as possible. >25 SEC.-NORMAL Cardiopulmonary Reserve (CPR) 15-25 SEC- LIMITED CPR <15 SEC- VERY POOR CPR (Contraindication for elective surgery) 25- 30 SEC - 3500 ml VC 20 – 25 SEC - 3000 ml VC 15 - 20 SEC - 2500 ml VC 10 - 15 SEC - 2000 ml VC 5 - 10 SEC - 1500 ml VC www.anaesthesia.co.in

  26. BED SIDE PFT 2) Single breath count: After deep breath, hold it and start counting till the next breath. • N- 30-40 COUNT • Indicates vital capacity www.anaesthesia.co.in

  27. BED SIDE PFT 3) SCHNEIDER’S MATCH BLOWING TEST: MEASURES Maximum Breathing Capacity. Ask to blow a match stick from a distance of 6” (15 cms) with- • Mouth wide open • Chin rested/supported • No purse lipping • No head movement • No air movement in the room • Mouth and match at the same level www.anaesthesia.co.in

  28. BED SIDE PFT • Can not blow out a match • MBC < 60 L/min • FEV1 < 1.6L • Able to blow out a match • MBC > 60 L/min • FEV1 > 1.6L • MODIFIED MATCH TEST: DISTANCE MBC 9” >150 L/MIN. 6” >60 L/MIN. 3” > 40 L/MIN. www.anaesthesia.co.in

  29. BED SIDE TEST 4) COUGH TEST: DEEP BREATH F/BY COUGH • ABILITY TO COUGH • STRENGTH • EFFECTIVENESS INADEQUATE COUGH IF: FVC<20 ML/KG FEV1 < 15 ML/KG PEFR < 200 L/MIN. VC ~ 3 TIMES TV FOR EFFECTIVE COUGH. A wet productive cough / self propagated paraoxysms of coughing – patient susceptible for pulmonary Complication. www.anaesthesia.co.in

  30. BED SIDE TEST 5) FORCED EXPIRATORY TIME: After deep breath, exhale maximally and forcefully & keep stethoscope over trachea & listen. N FET – 3-5 SECS. OBS.LUNG DIS. - > 6 SEC RES. LUNG DIS.- < 3 SEC www.anaesthesia.co.in

  31. BED SIDE PFT 6) WRIGHT PEAK FLOW METER: Measures PEFR (Peak Expiratory Flow Rate) N – MALES- 450-700 L/MIN. FEMALES- 350-500 L/MIN. <200 L/ MIN. – INADEQUATE COUGH EFFICIENCY. 7) DEBONO WHISTLE BLOWING TEST: MEASURES PEFR. Patient blows down a wide bore tube at the end of which is a whistle, on the side is a hole with adjustable knob. As subject blows → whistle blows, leak hole is gradually increased till the intensity of whistle disappears. At the last position at which the whistle can be blown , the PEFR can be read off the scale. www.anaesthesia.co.in

  32. MEASUREMENT OF TV & MV 8)Wright respirometer: measures tv, mv (15 secs times 4) • Simple and rapid • Instrument- compact, light and portable. • Disadvantage: It under- reads at low flow rates and over- reads at high flow rates. • Can be connected to endotracheal tube or face mask • Prior explanation to patients needed. • Ideally done in sitting pos. • MV- instrument record for 1 min. And read directly • TV-calculated and dividing MV by counting Respiratory Rate. • Accurate measurement in the range of 3.7-20l/min.(±10%) • USES: 1)BED SIDE PFT • 2) ICU – WEANIG PTS. FROM Ventilation. www.anaesthesia.co.in

  33. DEBONO’S WHISTLE www.anaesthesia.co.in

  34. BED SIDE PFT 9) MICROSPIROMETERS – MEASURE VC. 10) BED SIDE PULSE OXIMETRY 11) ABG. www.anaesthesia.co.in

  35. CATEGORIZATION OF PFT • MECHANICAL VENTILATORY FUNCTIONS OF LUNG / CHEST WALL: A) STATIC LUNG VOLUMES & CAPACITIES – VC, IC, IRV, ERV, RV, FRC. • DYNAMIC LUNG VOLUMES –FVC, FEV1, FEF 25-75%, PEFR, MVV, RESP. MUSCLE STRENGTH • VENTILATION TESTS – TV, MV, RR. www.anaesthesia.co.in

  36. CATEGORIZATION OF PFT 2) GAS- EXCHANGE TESTS: A) Alveolar-arterial po2 gradient B) Diffusion capacity C) Gas distribution tests- single breath N2 test. - Multiple Breath N2 test - Helium dilution method. - Radio Xescinitigram. D) ventilation – perfusion tests A) ABG B) single breath CO2 elimination test C) Shunt equation www.anaesthesia.co.in

  37. CATEGORIZATION OF PFT 3) CARDIOPULMONARY INTERACTION: A) Qualitative tests: - History , examination - Abg - Stair climbing test B) Quantitative tests - 6 min. Walk test (gold standard) www.anaesthesia.co.in

  38. STATIC LUNG VOLUMES AND CAPACITIES • SPIROMETRY : CORNERSTONE OF ALL PFTs. • John hutchinson – invented spirometer. • “Spirometry is a medical test that measures the volume of air an individual inhales or exhales as a function of time.” • Measures VC, FVC, FEV1, PEFR. • CAN’T MEASURE – FRC, RV, TLC. www.anaesthesia.co.in

  39. PREREQUISITIES • Prior explanation to the patient • Not to smoke /inhale bronchodilators 6 hrs prior or oral bronchodilators 12hrs prior. • Remove any tight clothings/ waist belt/ dentures • Pt. Seated comfortably If obese, child < 12 yrs- standing www.anaesthesia.co.in

  40. PREREQUISITES • Nose clip to close nostrils. • Exp. Effort shld last ≥ 4 secs. • Should not be interfered by coughing, glottic closure, mechanical obstruction. • 3 acceptable tracings taken & largest value is used. www.anaesthesia.co.in

  41. SPIROMETER • Double walled cylinder with water to maintain water tight seal • Inverted bell (9 l) attached to pulley which carries a counterweight and pen – moves up and down as volume of bell changes • BREATHING ASSEMBLY i.E. Unidirectional breathing valves with mouth piece. www.anaesthesia.co.in

  42. Flow-Volume Curves and Spirograms • Two ways to record results of FVC maneuver: • Flow-volume curve---flow meter measures flow rate in L/s upon exhalation; flow plotted as function of volume • Classic spirogram---volume as a function of time www.anaesthesia.co.in

  43. Normal Flow-Volume Curve and Spirogram www.anaesthesia.co.in

  44. Spirometry Interpretation: So what constitutes normal? • Normal values vary and depend on: • Height • Age • Gender • Ethnicity www.anaesthesia.co.in

  45. Acceptable and Unacceptable Spirograms (from ATS, 1994) www.anaesthesia.co.in

  46. Measurements Obtained from the FVC Curve • FEV1---the volume exhaled during the first second of the FVC maneuver • FEF 25-75%---the mean expiratory flow during the middle half of the FVC maneuver; reflects flow through the small (<2 mm in diameter) airways • FEV1/FVC---the ratio of FEV1 to FVC X 100 (expressed as a percent); an important value because a reduction of this ratio from expected values is specific for obstructive rather than restrictive diseases www.anaesthesia.co.in

  47. Obstructive Disorders Characterized by a limitation of expiratory airflow so that airways cannot empty as rapidly compared to normal (such as through narrowed airways from bronchospasm, inflammation, etc.) Examples: Asthma Emphysema Cystic Fibrosis Restrictive Disorders Characterized by reduced lung volumes/decreased lung compliance Examples: Interstitial Fibrosis Scoliosis Obesity Lung Resection Neuromuscular diseases Cystic Fibrosis Spirometry Interpretation: Obstructive vs. Restrictive Defect www.anaesthesia.co.in

  48. Normal vs. Obstructive vs. Restrictive (Hyatt, 2003) www.anaesthesia.co.in

  49. Obstructive Disorders FVC nl or↓ FEV1 ↓ FEF25-75% ↓ FEV1/FVC ↓ TLC nl or ↑ Restrictive Disorders FVC ↓ FEV1 ↓ FEF 25-75% nl to ↓ FEV1/FVC nl to ↑ TLC ↓ Spirometry Interpretation: Obstructive vs. Restrictive Defect www.anaesthesia.co.in

  50. FVC Interpretation of % predicted: 80-120% Normal 70-79% Mild reduction 50%-69% Moderate reduction <50% Severe reduction FEV1 Interpretation of % predicted: >75% Normal 60%-75% Mild obstruction 50-59% Moderate obstruction <49% Severe obstruction <25 y.o. add 5% and >60 y.o. subtract 5 Spirometry Interpretation: What do the numbers mean? www.anaesthesia.co.in

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