Pulmonary function test, bedside pft.pptx

Pulmonary function test

1. PFT, Spirometry, Flow volume loops PRESENTER : Dr. MAMATHA MODI S (junior resident , anaesthesiology, GMC Kozhikode) ) MODERATOR : Dr. SHYAM KUMAR (assistant professor, , anaesthesiology, GMC Kozhikode)

2. Pulmonary function tests

3. USES OF PFT Screen for type of disease.. Quantify severity Follow progression of disease Observe response to therapy Predict post operative complications Obtain baseline information To determine further treatment goals Epidemiologic surveys

4. Contraindications of PFT… RELATIVE C/I MI within 1 month Unstable angina within 1 month Recent thoraco-abdominal surgery Recent ophthalmic surgery Thoracic, abdominal or cerebral aneurysm Current pneumothorax Active hemoptysis

5. TISI guidelines American college of physicians Age > 70 Lung resection Obese patients H/o smoking, dyspnea Thoracic surgery Cardiac surgery Upper abdominal surgery Upper abdominal surgery History of cough/ smoking Lower abdominal surgery Any pulmonary disease Uncharacterized pulmonary disease

6. p hysiological factors… Age Gender Height Weight Race

7. Classification of PFT

8. MECHANICAL VENTILATORY FUNCTION TESTS Bedside pulmonary function tests Spirometry static lung volumes and capacities dynamic lung volumes

9. Gas exchange tests Alveolar arterial p02 gradient Diffusion capacity Gas distribution tests single breath N2 test multiple breath N2 tests helium dilution method radio Xe scintigram

10. CARDIOPULMONARY INTERACTION: • Qualitative tests: 1) History , examination 2) ABG • Quantitative tests 1) 6 min walk test 2) Stair climbing test 3)Shuttle walk 4) CPET(cardiopulmonary exercise testing

11. Bed side pulmonary function tests

12. BEDSIDE PFT RESPIRATORY RATE Sabrasez breath holding test Sabrasez single breath count SCHNEIDER’S MATCH BLOWING TEST GREENE AND BEROWITZ COUGH TEST FORCED EXPIRATORY TIME Wright’s spirometer DE ‐BONO WHISTLE BLOWING TEST MICROSPIROMETERS Wheeze test Bedside pulse oximetry ABG

13. RESPIRATORY RATE Essential yet frequently undervalued component of PFT Imp evaluator in weaning & extubation protocols Increase RR ‐ muscle fatigue ‐ work load ‐ weaning fail 12-15 /MIN Newborn 30 to 60 Infant (1 to 12 months) 30 to 60 Toddler (1 to 2 years) 24 to 40 Preschooler (3 to 5 years) 22 to 34

14. Sabrasez breath holding test

15. Sabrasez breath holding test Ask the patient to take a full but not too deep breath & hold it as long as possible. Measures cardio pulmonary reserve • >25 SEC. ‐NORMAL Cardiopulmonary Reserve (CPR) • 15 ‐25 SEC ‐ LIMITED CPR <15 sec. - very poor cpr ( c/I 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 10 SEC ‐ 1500 ml VC

16. Sabrasez single breath count The patient is asked to take a deep breath followed by counting 1, 2, 3…… till he/she cannot hold breath Count 30-40 = normal vital capacity

17. SCHNEIDER’S MATCH BLOWING TEST

18. SCHNEIDER’S MATCH BLOWING TEST MEASURES Maximum Breathing Capacity . Ask to blow a match stick from a distance of 6” (15 cm) with Mouth wide open No purse lipping No head movement No air movement in the room Mouth and match at the same level

19. • 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

20. GREENE AND BEROWITZ COUGH TEST DEEP BREATH F/BY COUGH ABILITY TO COUGH STRENGTH EFFECTIVENESS INADEQUATE COUGH IF: FVC< 15 ML/KG PEFR < 200 L/MIN. A wet productive cough / self propagated paraoxysms of coughing – patient susceptible for pulmonary Complication

21. FORCED EXPIRATORY TIME

22. FORCED EXPIRATORY TIME After deep breath, exhale maximally and forcefully & keep stethoscope over trachea & listen. N/l 3 ‐ 5 SECS. OBS.LUNG DIS. ‐ > 6 SEC RES. LUNG DIS. ‐ < 3 SE

23. Wright’s spirometer

24. Wright’s spirometer Measures the Tidal Volume and Minute Volume of the patient Simple and quick assessment . can be connected to an endotracheal tube or face mask. Ideally done in the sitting position, the patient is asked to breathe through the instrument for one minute and the respiratory rate is noted. The minute ventilation is recorded and read directly from the instrument. The TV is calculated by dividing the MV by Respiratory rate. A fairly accurate measurement can be obtained within the range of 3.7 to 20 L (± 10%). It is very useful tool for bedside PFT and in ICU during weaning off patients from the ventilator.

25. DE ‐BONO WHISTLE BLOWING TEST MEASURES PEFR . Patient blows down a wide bore tube at the end of which is a whistle is present. 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.

26. MICROSPIROMETERS Measures Vital capacity

27. Wheeze test 5 deep expiration/inspiration Auscultated Chest expansion n/l = 4-5 cm in adults

28. Bedside pulse oximetry ABG

29. SPIROMETRY

30. Corner stone of all PFT • 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.” • CAN’T MEASURE – FRC, RV, TL

31. Procedure Pt inhales as much as air as possible and then exhales rapidly Exhalation should be done rapidly and forcefully for as long as flow can be maintained The patient should exhale for at least 6 seconds At the end of forced exhalation the patient inhales again fully and as rapidly as possible

32. Acceptable spirometry… Begins from full inflation Shows minimal hesitation at start of forced exhalation Show explosive start of forced exhalation Absence of coughing during the first second of forced exhalation Meets one of three criteria at end of the test Smooth curvilinear rise of volume-time tracting to a plateau of at least 1 second duration Forced expiratory time >15seconds in the absence of an expiratory plateau Termination of the forced exhalation due to medical complications.

33. Tidal volume Volume of air moving inhaled or exhaled during quiet respiration 6-8ml/kg 500 ml in adults female,  IBW = 45.5 + 0.9 * (height [cm] - 152) male,  IBW = 50 + 0.9 * (height [cm] - 152) .

34. Inspiratory reserve volume Maximum volume of air inhaled from end inspiratory tidal position 3.2-3.6 L

35. Expiratory reserve volume Maximum volume of air exhaled from end expiratory tidal position Around 1.2 L

36. RESIDUAL VOLUME The volume of air remaining in lungs after maximal exhalation constitutes RV Rv cannot be measured directly by spirometry FRC-ERV 1.2-2 l in adults 20-25ML/KG

37. Total Lung Capacity (TLC) Sum of all volume compartments or volume of air in lungs after maximum inspiration (4‐6 L)

38. Vital capacity maximum volume of air exhaled from maximal inspiratory level TLC – RV (60‐70 ml/kg) 5000ml VC reduced in both obstructive and restrictive lung disease

39. Inspiratory capacity maximum volume of air that can be inhaled from the end‐expiratory tidal position is IC. (2400‐3800ml). TV +IRV

40. Functional residual capacity

41. Functional residual capacity Volume of air remaining in lung at end of normal passive expiration a key component in the measurement of lung volumes.  Cannot be measured by simple spirometer FRC= RV+ERV Approximately 2400ml for a 70kg adult 30-35ml/kg 40% of TLC

42. PHYSIOLOGY Reserve of oxygen during apnea during APNEA, FRC oxygenates blood passing through lung Prevention of airway collapse keeps the alveoli partially inflated at end-expiration this prevents airway collapse and atelectasis Minimizes pulmonary vascular resistance since FRC prevents airway collapse, it helps in keeping small intra- alveolar vessels patent effect on ventilation perfusion relationship FRC reduction causes atelectasis and lung collapse results in venous admixture and arterial hypoxemia

43. Significance Gas exchange Dilute inhaled toxic gases Preoxygenation fills FRC FRC filled with o2 500 to 2400ml

44. Preoxygenation A normal adult lying supine (i.e. with an FRC of about 2000 mL) with a typical O2 consumption (250 mL/min) will exhaust the O2 within their lungs in just over 1 min. Critical hypoxemia occurs even more rapidly in patients with reduced FRC or an increased rate of O2 consumption .Pre-oxygenation involves the patient breathing 100% O2 for a period of time (traditionally 3 min)prior to induction of anaesthesia. Over time, N2 molecules within the FRC are replaced by O2 molecules. If the same supine patient as above had an FRC full of O2, their lungs would contain 1800 mL of O2. The increased O2 reservoir would allow the anaesthetist 8 min to secure the airway before onset of hypoxemia.

45. Factors affecting FRC INCREASED FRC increasing height male gender peri-bronchial fibrosis obstructive lung disease increased peak end expiratory pressure open chest prone position

46. DECREASED FRC Short stature female gender restrictive lung disease ARDS pulmonary edema tb, sarcoidosis pregnancy ,ascites major abdominal surgery anaesthesia /sedation neuromuscular diseases b/l diaphragmatic palsy supine trendelenberg position obesity

47. Effects of anaesthesia FRC reduced by 20% FRC reduced both in controlled and spontaneous ventilation Mechanism loss of inspiratory muscle tone loss of tone of accessory muscles loss of tone of diaphragm absorption atelectasis due to high Fi02

48. CONSEQUENCES atelectasis postoperative hypoxia Causes of post-operative decrease in FRC incisional pain diaphragmatic dysfunction bowel distension ,local irritation , pneumo peritoneum

49. Prevention 30 degree head up PEEP CPAP

50. RESTORATION OF FRC Early and active lung expansion maneuvers deep breathing incentive spirometry CPAP recruitment maneuvers sighs: can generate upto 40 H20 pressure Adequate analgesia

51. BODY PLETHYSMOGRAPHY GOLD STANDARD Measure FRC using BOYLES LAW Pt placed in a body box /pneumotachometer Changes in volumes are determined by changes in pressure within body box. however this method requires sophisticated and expensive equipment Also measures air which is trapped behind closed airways

52. Helium dilution method Measures dilution of air present in lungs at end expiration by inhaled helium. Spirometer is filled with 10% helium in oxygen Amount of helium at beginning of test (c1) Initial volume of helium-oxygen mixture –v1 Patient is asked to breathe normally starting from end tidal expiration The helium enters lungs and spreads to new concentration C2 V2 is unknown volume in lungs

53. Helium dilution is calculated by using conservation of mass principle V2 = v1(c1-c2) c2 Does not measure air which is trapped behind closed airways Older, simpler, less accurate

54. Nitrogen washout method Aka fowlers method Based on washing out nitrogen by breathing in 100% oxygen Subject inhales 100% 02 for 7 minutes and exhales through a one-way valve Total quantity of n2 washed out of lungs by breathing in oxygen is measured When the N2 level falls to zero, all N2 present in the lungs at the beginning of the test has been washed out.

55. The total volume of gas expired and N2 in the expired gas is measured. FRC= (volume of N2 washed out) – (N2 tissue extraction) initial – final N2 concentration. N2 tissue extraction is calculated as (Body Surface Area x 96.5) + 35 0.8

56. Other methods CT scan Multiple breath SF6 procedure

57. DYNAMIC LUNG TESTS

58. FORCED VITAL CAPACITY (FVC) The FVC is the maximum volume of air that can be breathed out as forcefully and rapidly as possible following a maximum inspiration.   It is characterized by full inspiration to TLC followed by abrupt onset of expiration to RV  indirectly reflects flow resistance property of airways . Normal patients, FVC = VC Measurements of FVC depends on patient effort and cooperation IN OBSTRUCTIVE LUNG DISEASE = FVC REDUCED IN RESTRICTIVE LUNG DISEASE = FVC REDUCED FVC <15ML/KG increases risk of postoperative pulmonary complications

59. Taking into consideration factors like age, sex and ethnicity, the value of FRC is predicted and the Forced spirogram is interpreted as the percentage of the predicted. 80-120% of predicted – Normal, 70-79% – Mild reduction 50%-69% – Moderate reduction.

60. FORCED EXPIRATORY VOLUME (FEV t ) Volume of gas expired over a given time interval during the fvc manuevar. “t” time elapsed in seconds from onset of expiration ..Measure of flow It is a useful measure of how quickly the lungs can be emptied and thus measures the general severity of the airway obstruction. Depends of patients effort and cooperation Reduced in both obstructive and restrictive diseases FEV 0.5 50-60% FEV 1 75-85% FEV 2 94% FEV 3 97%

61. FEV1/FVC Represents the ratio of FEV 1 /VC during the first second of FVC maneuver Normally at least 75% of VC exhaled out during the 1 st second Reduced values are observed in obstructive disorders NORMAL in restrictive disorders >75% -Normal, 60% ‐ 75% Mild obstruction 50% ‐ 59% depicts moderate obstruction.

62. Forced expiratory flow Measure of how much volume can be expired from lungs as a flow rate. Each quartile of fvc expressed as FEF value FEF 25% amount of air forcefully expelled out in first 25% of FVC test FEF 50% amount of air expelled out from lungs during first half of FVC test

63. (FEF25%) Forced Expiratory Flow at 25% of FVC   indicative of the condition of fairly large to medium size bronchi . 

64. (FEF50%) Forced Expiratory Flow at 50% of FVC  This landmark is at the midpoint of the FVC indicates the status of medium to small airways.

65. FEF75% Forced Expiratory Flow at 75% of FVC This landmark indicates the status of small airways The damage done by most chronic pulmonary diseases show up in the smallest airways first and early indications of this damage begin to appear toward the end of the expiratory part of the Flow Volume Loop.

66. Peak expiratory flow rate

67. Peak expiratory flow rate Maximum flow rate during an FVC manoeuvre occurs in initial 0.1 s and the expiratory flow at this time is termed as PEFR. Useful to measure response to bronchodilator therapy 450 ‐ 700 l/min in males 300 ‐ 500 l/min in females.

68. Post –bronchodilator spirometry Used to determine reversibility of airflow limitation Indications Asthma Copd Evidence of airway obstruction on baseline spirometry Increase in FEV1 >12% OR 200ml suggests acute bronchodilator responsiveness

69. Procedure MDI ALBUTEROL 4 inhalations of 90-100ug proper MDI technique is vital 15min after b/d spirometry is repeated

70. Limitations of spirometry not disease specific cannot be used as sole screening tool variable values depending upon age , sex, gender effort dependent results Specific measurements do not predict post-op pulmonary complications

71. FLOW VOLUME LOOPS

72. Graphic analysis of inspiratory and expiratory flow rates against lung volume X axis- lung volume Y axis – flow rates Expiratory flow rate – above the horizontal Inspiratory flow rate – below the horizontal Changes in shape of loop – aid in diagnosis and localization

73. Procedure Pt is instructed to: take forceful inspiration upto total lung capacity take forceful expiration to residual volume

74. Normal curve

75. EXPIRATORY CURVE Characterized by a rapid rise in the curve to peak flow rate, Followed by linear fall in flow rate as patient exhales towards RV Expiratory curve divided into 4 quarters Flow rate at which 25% VC has been exhaled =FEF 25 Flow rate at midpoint of VC =FEF50 75% VC FEF75 During exhalation maximal flow occurs during first 25% Flow rates decreases progressively First 1/3 rd VC effort dependent

76. INSPIRATORY CURVE Symmetrical saddle shaped curve Flow rate at midpoint – FIF50

77. Obstructive lung disease

78. Scalloping of expiratory limp of loop Asthma , bronchioloitis, bronchiectasis, Increased TLC, reduced PEFR , Curvilinear expiratory limp with upward concavity Reduction in flow rate in effort independent part Initial part of expiratory curve represents large airway usually emptied quickly

79. Restrictive lung disease

80. Interstitial lung disease Kyphoscoliosis , Obesity, Lung Resection, Neuromuscular diseases, Cystic Fibrosis reduction in TLC, FRC, RV. Rapid decrease in inspiratory flow rate Increased expiratory flow rate peak flow rates reduced

81. Variable intrathoracic obstruction Inspiratory limb normal Flattening of expiratory limb Retrosternal goitre Intrathoracic tracheal tumors Intrathoracic tracheomalacia Bronchial tumors Bronchogenic cysts Mechanism : pleural pressure negative during inspiration, pressure becomes positive during expiration E/I <1

82. Variable extr athoracic obstruction Normal expiratory limb Flattening of inspiratory loop Vocal cord palsy Laryngomalacia Obstructive sleep apnea syndrome Pharyngeal muscle weakness Neuromuscular disorders E/I>1

83. Fixed upper airway obstruction Can result in intrathoracic or Ext rathoracic obstruction Tracheal stenosis Goitre Tumors No significant change during inspiration and expiration Flatt ening of both inspiratory and expiratory loop E/I = 1

84. TESTS FOR GAS EXCHANGE FUNCTION

85. ALVEOLAR‐ARTERIAL O2 TENSION GRADIENT: Sensitive indicator of detecting regional V/Q inequality N value in young adult at room air = 8 mmHg to up to 25 mmHg AbN high values at room air is seen in asymptomatic smokers & chr. Bronchitis (min. symptoms) A‐a gradient = PAO2 ‐ PaO2 PAO2 = alveolar PO2 (calculated from the alveolar gas equation) PaO2 = arterial PO2 (measured in arterial gas)

86. DIFFUSION CAPACITY   It implies the maximum transfer ability of the lung and is governed by its structural and functional properties. The gas has to travel through several barriers as it moves from the alveolus to the haemoglobin binding site • Normal‐ 20‐30 ml/min/mm Hg • Depends on: ‐ thickness of alveolar -capillary membrane ‐ hemoglobin concentration ‐ cardiac output

87. SINGLE BREATH TEST USING CO • Pt inspires a dilute mixture of CO and hold the breath for 10 secs. • CO taken up is determined by infrared analysis: DLCO = Vco PACO-PCCO, Vco is rate of disappearance of CO, PACO is alveolar concentration of CO, PCCO partial pressure of CO in blood. • DLO2 = DLCO x 1.23

88. • Why CO? its uptake is easy to measure it follows the same diffusion pathway that of oxygen. High affinity for Hb which is approx. 200 times that of O2 , so does not rapidly build up in plasma Under N condition it has low bld conc ≈ 0 Therefore, pulm conc.≈ 0

89. DECREASE(< 80% predicted) INCREASE(> 120‐140% predicted) Anemia Polycythemia Carboxyhemoglobin Exercise Pulmonary embolism Congestive heart failure Diffuse pulmonary fibrosis Pulmonary emphysema

90. Tests for cardiopulmonary reserve

91. Incremental Shuttle walk test

92. Incremental Shuttle walk test • The patient walks between cones 9 meters apart with increasing pace  in time to a set of auditory beeps . Initially, the walking speed is very slow, but each minute the required walking speed progressively increases. The patient walks for as long as they can until they are either too breathless or can no longer keep up with the beeps, at which time the test ends. • The subject walks until they cannot make it from cone to cone between the beeps. • Less than 250m or decrease SATURATION> 4% signifies high risk

93. 6 min walk test   100-ft hallway This test measures the distance that a patient can quickly walk on a flat, hard surface in a period of 6 minutes (the 6MWD)  test is a global assessment and does not specifically identify the respiratory system as the source of the limitation. A 6MWT < 600 m corresponds to a VO2 max of 15 ml/kg/min.

94. Stair climbing and 6 ‐minute walk test • This is a simple test that is easy to perform with minimal equipment.

95. CONCLUSION PFTs is an important tool which add to or aid in exclusion of a diagnosis. A combination of patient’s clinical history as well as supporting data with required knowledge of interpretation of tests will help in proper evaluation of patient prior to surgery and develop an anaesthetic plan of management for better outcome.

96. FAQ Bedside PFT *** FRC*** SPIROMETRY

97. Thank you