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Lung Function Test: Basics & Interpretation

May 15 | 5:30 AM

PFTs are typically interpreted by comparing data collected in a single patient or subject to reference (predicted) values based on healthy participants. Predicted values should come from studies of normal or healthy persons with similar anthropometric characteristics. Lung volumes, spirometry and flow volume loops, and diffusing capacity are all components of PFTs. PFTs are commonly requested to: Look for indications of respiratory disease when patients report with respiratory symptoms (e.g. dyspnea, cough, cyanosis, wheezing, etc.), Assess for lung disease progression, monitor the efficacy of a specific treatment, and so on. Let's learn the fundamentals of PFT with Dr. Salil Bendre, a famous Medflix select faculty.

[Music] welcome back to one amazing session uh we all are always looking forward to your sessions and we get amazing feedback from all the audience so welcome back and i'm glad you could give us some time on sunday morning uh thank you so much uh so two new users uh i'll just introduce uh you to sir sir is amazing teacher sir metric select faculty service consultant physician transplant physician practicing at global hospital massena hospital uh and uh he has taken lot of sessions on pulmon in pulmonology uh and today we are back with amazing session on interpretation of the pulmonary function test basic and uh so we'll go through it as well so over to you sir yeah so good morning everyone so uh we will be starting with a session today which is going to be a little little tough for me i should say because to teach or to talk about lung function tests on a virtual platform where i know i can't really see you people it's going to be a little tough job for me but rucha thanks let's hope it goes well so uh so let's start with the first slide and i've i i want uh all the people who are listening to us today to please have a pen and paper or a diary because you need to note down few things without that it's not going to be possible to really learn interpretation of spirometry okay so i i would request all of you to take a pen and paper or a diary there will be certain uh digits to be written certain uh you know certain short forms to be mentioned volumes capacities so all those who are interested in really learning take it and we start from the basics of our breathing okay let's just start from the basics of breathing i assume that all of you who are locked in today are our students or practitioners or even for that matter uh consultants who are there with us and who are interested in respiratory system because finally it's all about the respiration and the respiratory system and when we talk of spirometry it is actually the physics of science okay it's actually the physics of science which we are going to discuss technicalities we are going to discuss a few definitions of what is a capacity what is the volume which as a clinician we pay attention but we are usually interested in knowing the diagnosis of the disease we are interested in knowing the complications of a disease we are interested in knowing the treatment of a disease but how does this spirometry help you is by imagining or having a patient in front of you who has got breathing problem okay breathing difficulty so he's got breathing difficulties breathing at a very fast rate what we call as tachypnea but when he's breathing fast his rate of breathing increases but the volume which he breathes in every breath reduces okay so the volume will reduce but his rate will increase and this volumes which are generated are going to be the basis of analyzing the problem in the lung function here we are not going to discuss or diagnose tb or pneumonia or ild we are going to see what is the defect in the lung functions so if you put the other way around if a person is having breathlessness whenever there is a inspiration it's an active process so the breath goes in by an active maneuver we breathe in actively but exhalation is by passive recoil it is by a natural instinct of the lung to recoil passively it doesn't have the pressure to exhale out the same amount of air which he had inhaled so there is lot of exhalation which is happening but it is going through a narrow passage when i say that the passive recoil is happening means the recoil is there there is a narrow passage but unfortunately the passage doesn't open during the exhalation and that's why the air has to pass through a narrowed airway so again what is happening in this situation where there is a narrowing in the airway is that the volume is taking a longer time to get exhaled okay the amount of air which he had inhaled say it was in a specific duration say five seconds or six seconds he is taking a longer time to exhale the same volume understand so these are the things which we are going to understand when we are trying to talk about spirometry so a patient who is breathless his technique he comes to you in front of you he is sitting his respiratory rate is a 34 per minute is breathing very fast but inadvertently the volume with which he is breathing in the volume of air with which he is breathing in is reducing and what is that volume called when he breathes normally or the volume of air which is breathing in his breath is called as a tidal volume so his tidal volume is reducing when he is taking when he is breathless and if there is an airway narrowing then the volume takes some more time to get exhaled so the time of acceleration increases during the expiratory phase in a patient who has got a narrowed airways so that's that's please try to understand that we'll go back to the basic diagram which we have all learned in physiology really long back maybe whoever have passed out really maybe few years back or five six years back but you need to remember this diagram and i wish that all of you read the different boxes which are mentioned here so there is a inspiratory reserve volume which is over and above a normal tidal breathing there is a expiratory reserve volume which is over and above the normal expiration so once you are breathing normally right now let's try this by all of you when you are breathing in normally and exhaling normally the volume of air is called as the tidal volume but if you take a breath over and above a normal breath it is called as the inspiratory reserve volume or irv in short form irv and when a person is exhaling over and above normal exhalation it is the erv expiratory reserve volume now at the end of expiration the lung doesn't close the lung doesn't deflate completely but some amount of air remains in the lung which doesn't allow the alveoli to close and that volume is called as the residual volume understood so remember there is an inspiratory user volume there is a tidal volume there is an expiratory user volume and there is a residual volume now if you see the next box it says that vital capacity is the total of inspiratory reserve volume plus the tidal volume plus the expiratory reserve volume so these three together form what is called as the vital capacity is vital for our gas exchange it is vital for our oxygenation it is vital for the carbon dioxide to be exhaled out so that's why it's called as the vital capacity the amount which is remaining in the lungs other than the vital capacity is the residual volume okay it's the residual volume and of course the vital capacity plus the residual volume is going to give us the total lung capacity i hope you are understanding i am going slow because as we proceed this this diagram is going to come again and again and again in front of you now if you have seen a spirometry being done okay we'll call it a spirometry we are not calling it lung function test we are going to call it spirometry if you are seen a spirometry being done then the person is told to take a deep breath zombie saski so he's taking a deep breath deep breath deep breath deep breath as deep as possible that means he is reaching to the inspiratory reserve volume and then he is told to forcefully exhale so he is told to exhale exhale exhale exhale exhale exhale as much as possible as much as possible so he exhales maximally so in short what are we measuring in that in this we are told the patient to take a deep breath and we have told the patient to exhale forcefully now at the end of forced exhalation what volume remains inside is the residual volume that we are not measuring we are only measuring the vital capacity and it is a forceful maneuver it is not the tidal volume it is not the tidal breathing we are forcing him to do it we are telling him take a deep breath we are telling him exhale forcefully it's a forced maneuver so the parameter is called as the forced vital capacity f v c so please write it down f v c fvc means forced vital capacity imagine that this is the lung and he is inhaling forcefully and exhaling forcefully okay and some air is remaining inside we are measuring this volume which is inhaling and exhaling which is the forced vital capacity if at all if at all we don't allow his lungs to inflate means there is something outside the lung imagine these are the lungs they are inflating exhaling but now i i don't allow the lungs to inflate so he is unable to inflate his lungs in short his tidal volume the inspiratory tidal volume is reducing and he is exhaling the same reduced tidal volume which is the expiratory tidal volume so there will be reduction in the vital capacity if the patient is unable to inflate his lungs there is something outside the lungs which is not allowing the lungs to inflate that will reduce the vital capacity i hope you are understanding this so what would be the diseases which reduce the forced vital capacity we are talking of f b c we are talking only of f we see forced vital capacity is getting reduced it is getting reduced because the lungs are not able to inflate why they are not able to inflate because there is something outside the lungs now let's get our anatomy straight the lungs we saw talk of the nose the trachea the bronchi the bronchioles and the alveolus the last unit the final unit of the lung is the alveolus the lung ends at the alveolus outside the alveolus everything and anything are going to cause reduction in the forced vital capacity so give me an example of a disease which is outside the alveolus and gives rise to reduction in the forced vital capacity can anyone give me an example which is outside the alveolus any any one of you who can try it let's try our guesswork is also fine so if anyone can yes so as dr viren has said interstitial lung disease okay interstitium so the immediately we we have outside the alveolus the space which is called the interstitial space so that will give rise to reduced forced vital capacity force vital capacity is reduced in an interstitial lung disease we move a still outwards outside the interstitium there is a pleura okay outside the interstitium is the pleura so in a plural disease again the lung will not be able to inflate so the forced vital capacity will reduce so a plural disease it could be plural effusion it could be pneumothorax it could be pleural thickening so any of these diseases will cause reduced forced vital capacity let's come still outwards from the pleura rib cage okay rib cage so if the rib cage is abnormal so ribcage is attached to the spine and it is important for having the bucket handle and the pump handle movement of respiration so if the ribcage is abnormally aligned or the spine is abnormally shaped even then the forced vital capacity will reduce example would be as dr manuel is saying kyphos scoliosis so kyphos scoliosis itself can give rise to decreased forced vital capacity but you understand the logic behind it perfect answers everyone is giving so kyphos cole is come outside so outside the spa the rib cage muscles so if there is a difficulty or problem or neuromuscular abnormality where the muscular movements are not happening in that situation also there could be reduction in the forced vital capacity yes as doctor she is also saying there is pectus excavatum means there could be an abnormality in the ribcage in the sternum in the spine and that may cause reduction in the forced vital capacity there could be motor neuron disease there could be myasthenia there could be parkinson's there could be dystrophies so neuromuscular diseases can give rise to decreased force vital capacity it is decreasing because the inspiratory tidal volume is decreasing it is decreasing because the volume which the patient is inhaling is decreasing all right there could be a disease of the diaphragm for that matter because for inhalation and for inspiration the diaphragms have to contract the diaphragms are convex if they contract or become flattened or they become nor the the curvature is less than the diaphragmatic diseases may give rise to a decreased forced vital capacity so there could be these diseases which could be restricting the inflation on the lung okay so the word is that it is restricting the inflation of the lung and that's why they are called as restrictive lung diseases so restrictive lung diseases are those which can reduce the forced vital capacity a patient will come to you with breathlessness so looking at him you will not know whether the problem is in the airways within the airways or it is problem is outside the alveoli but if you see that this patient's fvc is reduced okay the forced vital capacity is reduced you can actually say that the problem is outside the alveoli okay so our our clinician instinct has to be coupled with the knowledge of the physics of respiration it has to be put together so if one of you say dr muhammad is sitting and he's having a patient who says i am feeling breathless since last three months i don't know what is happening when i walk i feel breathless when i climb staircases i feel breathless i am using inhalers i am not help it's not helping me i change the inhalers it is not helping me and let's assume that you do this patient's spirometry and its spirometry shows that the forced vital capacity is reduced it means the problem is outside the alveoli and if the problem is outside the alveoli will inhalers work they will not work because inhalers are going through the air passage and working in the lumen of the passage whereas in the patient having the fpc which is reduced the problem is actually outside the alveoli so it may not be helpful so you may immediately say your inhalers are not going to use they are not going to be beneficial so you need to investigate further so it could be interstitial lung disease it could be a plural disease it could be a kyphoscoliosis it could be diaphragmatic disease it could be neuromuscular disease so any of these changes can give rise to reduced forced vital capacity so forced vital capacity is nothing but a force manual it is measuring the vital capacity only we are not measuring the residual volume so spirometry the word spirometry implies we are measuring the force vital capacity we are not measuring the residual volume there is a different test to include or to measure the residual volume i hope you are understanding so i hope all of you have noted down fbc i am going to go back to another disease now in now in this next disease which we are going to discuss the patient has a problem within the lungs okay the previous disease was a problem outside the lung now we are talking of a problem within the lungs now what problem can happen within the lungs so the lungs are made up of airways there are tubes and they narrow so the only problem where a disease can happen in the airways is to narrow the passage is to make the passage thinner or narrower or smaller now if that is happening then if he's inhaling i'm giving an example let's say if he's inhaling 500 ml of air this person whose airway passage is narrowed is breathing in 500 ml of air now he has to exhale the same amount of air but unfortunately because of the narrowing the 4 500 of ml of air is not able to come in the same time because the volume is going to become lesser and lesser and the time of exhalation is going to be more and more and more understood so in a disease where the airway is narrow the volume which is reducing is the volume in the exhaled air and that volume in the exhaled air is called as expiratory volume it's called as the expiratory volume ev so please note it down ev so expiratory volume is reducing in a patient in whom the lumen of the airway is narrowed again we are saying that exhaled volume but now in a spirometry maneuver we are telling him take a deep breath and forcefully exhale we are telling him to exhale forcefully so the volume which is reducing in a spirometry will be the forced expiratory volume it is the forced expiratory volume so the f e v that is the forced expiratory volume will reduce in a person in whose lungs the airway is narrow okay so narrower the airway lesser will be the forced expiratory volume air has to pass through the airway normally and naturally whenever the passage is narrowed we explain it or we describe it as obstruction to the air passage and we term it as obstructive airway disease so now putting it everything together obstructive airway disease means the forced expiratory volume will be low restrictive lung disease the forced vital capacity will be low fvc will be low i hope you are able to understand and note it down maybe i am going absolutely basics because there would be a mixed audience coming in but the forced vital capacity is a restrictive lung disease forced expiratory volume reducing indicates obstructive airway disease so fev and fbc if this is clear then we go ahead with the third parameter okay third parameter you actually need to remember that when a person exhales the first blast of air the first blast of air which comes out it comes out from the larger airway means it comes out from the trachea then the next blast of air will come from the bronchi the next blast of air will come from the lobar bronchi the next volume of air will come from the bronchioles and the next volume of air comes from the respiratory bronchioles the smaller bronchioles which are called as small airways so the volume of air exhaled in the first second okay in the first second he started exhaling so you told the patient he's sitting in front of you for a spirometry and you tell him okay take a deep breath take a deep breath take a deep breath as deep as possible now you exhale with force you exhale with force you exhale with force and he started exhaling forcefully the the volume which he exhales in the first second is called or denoted as forced expiratory volume in the first second f e v one f e v one so this is a very important parameter f e v one so if i put up a question to any of you okay let's see if a patient's f e b one is reduced will it be obstructive or will it be restricted let's see who can answer this if a patient's fev1 is reduced will you call it restrictive or obstructive yes very good so it will be obstructive and if a patient's fvc is reduced it will be restricted so now we are very clear with the understanding fvc low restriction fev1 low obstruction now try to see this slide it is again a replica of the same slide but i am just trying to you know emphasize the point that if you are inhaling a specific amount of air and you are exhaling a specific amount of air the expiratory volume will be a part of the vital capacity right the expiratory i think we'll stick to this only this was easier to understand so the expiratory volume will be a part of the vital capacity i hope you are understanding this concept we are going coming to the fourth point one is we talked about fvc second which we talked about fev only the explanatory volume third is we talked about the fev1 and what i am trying to explain now to you is that the expiratory volume is actually a part of the forced vital capacity because vital capacity is the total it's the addition of inspiratory razor volume tidal volume and the explanatory volume so obviously the expiratory volume is going to be a part of the forced vital capacity all right so now let me put a question to you can it happen that because the forced vital capacity is decreased the forced expiratory volume can also be decreased because we are saying the forced vital capacity the entire volume is getting less and expiratory volume is a part of that so naturally the force vital capacity decreases even though fev1 is going to decrease even the fev1 is going to decrease i hope you are able to understand it again i say try to write it down it's very tough to understand it you may like or think you have understood it right now when i'm speaking to you but by 12 pm 1 pm everything will be vanishing i don't want that to happen so write it down that if the fpc reduces it is restrictive agreed very good if the fev1 reduces there is could be a problem because this fev1 could have actually reduced because the fvc has reduced so we are not very sure by just looking at the fev1 that is it really obstructive so we take help of another parameter and that parameter is the most important parameter of a spirometry and that is actually a ratio of fev1 upon the fvc so fev1 in the numerator and fvc in the denominator so we find the ratio the fev1 upon the fvc this ratio determines whether there is a real obstruction actual obstruction or is the fev1 reducing because the fpc has reduced so for the people who are really intently listening one i'll just summarize it again before we go to actual reports fbc low restriction i'm sure everyone has agreed to that fev1 low could be restriction or obstruction but we don't want to get confused so we take help of the next parameter which is the fev1 upon the fbc if this ratio is decreased okay so if the fev1 upon fbc is decreased then it is confirming obstructive airway disease okay it is confirming no doubt about it all right so if i ask you a random question in a patient whom i saw i was told that the fvc is reduced i was also told that the fev1 has also reduced so would you want to see the ratio of fev1 upon fbc yes so we need to really we need to see the ratio there is someone who said no we have to see the ratio of the fev1 upon fvc do not rely only on the one parameter of fev1 value you need to see the ratio to confirm obstruction so low fbc restriction decreased ratio of fev1 upon sc fvc means obstruction now we come to the next slide which actually tells us how are we going to analyze these different different uh ratios and how are we going to think about applying or analyzing is to the patient so this is a rough idea about what exactly happens when we say that there is air trapping and why the fpc decreases so there could be a patient uh who's fbc and normal person you can see the fvc and the residual volume residual volume is still the air within the lungs and in a patient if there is a lot of increase in the residual volume then there could be a reduction in the fvc so there could be things happening like that which could actually give rise to a decreased fvc but it is happening because of the residual volume we will come to a little simpler examples yes there could be mixed diseases so let's go to the severity now i want each one of you to write this down or take a picture of this because these are very important points which will actually help you in grading the restriction so is it mild restriction is it moderate restriction or is it severe restriction okay these are very important aspects which you should know now a patient who comes to you has got a couple of questions in his mind do you talk of a pneumonia even if you talk of ild even if you talk of asthma what is he going to ask you is it much more or it is just the beginning how serious it is how severe is it so this parameter objectively helps you to tell this person whether it is mild or moderate or severe one bottom line you all should know that please do not see one spirometry and diagnose a disease spirometry the major use the bulk of the use of spirometry is to know the trend of the disease the trend of the disease is it improving is it worsening was it better is it worse now are your treatments helping should you change your doses should you change the inhaler or your diagnosis was wrong so it helps in knowing the prognosis the outcome the trend of the disease you should have serial spirometry results to decide about what is happening in the patient's lung it's almost like example of a blood sugar test you start with a parameter the fbs and plbs you monitor the sugars and then titrate the dosages of your medicines so spirometry is also supposed to help you in telling us about the disease now when i say mild moderate severe one very important point which dr desai is talking about is this on comparison with normal so yes it is absolutely on comparison with normal so a spirometry is a test which has got calibration and there are parameters which are for a comparative assessment of the same age same sex and same height weight and erase okay so you should have all of the reports which come up they are always giving a comparative assessment comparing to a normal of predicted means this is the normal which is predicted for a patient whom you are doing a test say you have a 54 year old man who is 66 kilos and you are doing a spirometry so the percentage predicted here which we are writing 60 to 80 45 to 80 less than 45 these are all called as percentage predicted okay they are predicted the percentage so if the prediction is that it should be say three liters and it is only coming to one point five liter then it would be fifty percent of the predicted so fbc is in all these values which we look out into have got many different one is called as the actual value means in liters you will get actual value means in liters and percentages will be in the percentage of the predicted so please remember this for the fvc then we come to as we were talking about the fev1 upon the fvc ratio so this ratio is very important we have understood why it is important please again write this down or note it down or take a picture what you need to do is see the ratio the fev1 upon fvc ratio less than 70 percent means there is a obstructive airway disease all right so you see obstructive air vertices you find that the fev1 upon fvc ratio is in a patient say it is 55 so it is less than 70 so you feel oh i'm sure this is the obstructive airway this is because the fev one upon fvc ratio is less than 70. you know the guidelines you know this lecture has been taken netflix has arranged it you have been taught also and then you remember that okay fev1 fvc ratio less than 70 that means obstructive now the patient asks you sir yoga is this will this be treated by medicines or no you are explaining him to the report okay see your fe 1 fpc is 55 or 60 so it is less than the predicted it is less than 70 that means you have got obstructive airway disease now he asks you but then will this get reversed or not will this get better or no now that you are telling me it is less so we need to do one more test in the part of the spirometry which is called as the post bronchodilator testing post bronchodilator so as the name suggests post bronchodilator means we give we give him a inhalation a metered dose inhaler with salvation which is a short acting beta to agonist or a short-acting bronchodilator so it dilates the airways immediately we need to wait for 15 minutes and then we repeat the spirometry okay we need to repeat the spirometry and in the repetition of the spirometry what should we see we should be seeing the f e v one post bronchodilator fev1 is very very very important and you can classify the change in the fev1 and according to what are called as the initiative of obstructive error the gold criteria for copd this chart will tell you whether it's a mild copd moderate copd cv or copd or very severe copd so fev were more than 80 fpv 150 to 80 fpv 1 3250 and fever less than 30. so this will tell you the that severity of the copd so maybe it's a little confusing but i am going back to the first 10 minutes of the presentation which we started off you have understood that fbc low means restriction restriction means disease is outside the alveoli outside the alveoli means interstitium pleura ribcage spine diaphragm uh the the muscle muscles the neuromuscular junctions so all the or obesity for that matter obesity will also reduce the tidal volume so all of them will give us to reduce force vital capacity and we will term it as restrictive lung disease then we said that the expiratory volume is low in a patient having airway narrowing which we call as obstructive airway first force expiratory volume in the first second fev1 and we also mentioned that if the fev1 reduces it means that there is a obstruction but since the exploited volume is part of the fvc we consultant to know about obstruction so the fev1 upon fvc becomes movement so the fev1 upon fvc becomes more important than anything else okay fever upon fbc less than 70 indicates obstruction and if there is an obstruction you please see the post bronchodilator changes in the fpv one so again it's the it means the same the stage one stage stage two stage three stage four copd this is more methodical to really understand about copd because as pulmonologists we consider the treatment based on the severity on the stage of the copd we can't have a uh same treatment for every patient of copd so we need to monitor these spirometry reports and we come to the asthma so asthma is another obstructive airway disease so we got mild persistent asthma moderate persistent asthma and severe persistent asthma based on the global initiative asthma that is the jina guidelines the fev one predicted so you have got the fpv one more than or equal to 80 60 to 80 and less than 60 as a criteria to call it mild persistent moderate persistent or severe persistent so most important point you all should know it is that you should see the fev1 upon fvc so if you all have written this then we will try to see how a report actually looks like okay so this is how a report will look like so let's go by each column there are many things in the report but there is you need to go by in each column so there is a predicted value which comes in so predicted is as we said it's the normal for the given patient okay fvc first uh first horizontal row is the fbc so predicted is 2.22 over here then you can see another parameter called as the lower limit of normal it is the lln lower limit of normal now this is a new parameter which is which is incorporated in the test new parameter in the sense now the guidelines which have come up have not only the predicted but you should also have the lower limit of normal so the comparison is always taking into consideration the lower limit of normal now here i need to tell that not all spirometry report comes with these parameters there could be some spirometry report where the lln is not mentioned and in that only the predicted values are mentioned but to be more specific and more correct you should be ideally having a spirometry report which should have a lower limit of normal mentioned in it so you have got that lower limit of normal then you can see many trials trials means the patient has been told to do it and whichever is the best trial is selected or the best trial is selected so i would suggest that if you are going through this particular report then first look at the fvc okay can you see the fvc in this report and if you can see the fpc report then first is the column of of predicted second away second is uh lln third is the best then fourth is the trial fifth is the trial then you can come to a column called as percentage predicted okay percentage predicted so what is percentage predicted so this is an important point to be seen when we are talking of the fbc the percentage of the predicted all right so in fvc see the percentage predicted you are given the report what are you going to do first find out the fvc value where is it mentioned and in that row see the percentage predicted now how much is the percentage predicted here it is 88 percent now is it normal go through the chart which we we saw some time back try to see the chart which is gone sometime back is this fbc of 88 percent normal or it is is it suggestive of restriction yeah so it is normal so there is no restriction in this that is definite okay this is what first thing you need to do look at the fvc now i would suggest you should look at the parameter which will tell us about obstruction which parameter tells us about obstruction the fev1 upon the fvc now look at the fev1 upon fvc now these are all these the fever upon fvc is the ratio okay it's the ratio so you are going to see in the third column which is the 55 that is underlined over there 55 here you are not going to see that percentage predicted because here actually it's the ratio of the both the percentages so you are going to see is the 55 so here the fev1 upon fbc and the topmost statement over there is pre-bronchodilation pre-bronchodilation means before giving the bronchodilator the fev1 upon fvc was 55 okay it was 55 cut it so it was 55 can you see that try to see it i'll take some time and i'll wait for you all of you to see the fever upon fvc ratio is this 55 now after you after that in the same same horizontal row in the same horizontal row if you see the post bronchodilator post bronchodilator can you see the post bronchodilator was bronchodilator can you tell me how much is it the post bronchodilator it's mentioned in green it's mentioned in green the post bronchodilator best trial if you can see how much is it yeah so it's 62.6 correct it is 62.6 it may be a little mathematics also in this but i can't help it spirometry is supposed to be this way there's nothing i can do about it so you need to see the post bronchodilator and you saw the post bronchodilator it is 62.6 so the fev1 upon fvc post bronchodilator is also remaining below 70 percent okay it is not moving ahead of 70 percent okay so first thing we got that the fpc fvc was normal so there was no restriction then next we saw was the fev1 upon fbc so it was less than 70 that means you knew that this is an obstructive problem this is obstructive airway disease now you will also have to see the fev1 simultaneously so what is seen in the fev1 try to see the fvv1 so in fvv1 you will have to see the percentage predicted just below the fpc percentage predicted you will see the percentage predicted is 68 68. okay you can see the percentage predicted is 68. okay yeah so there is a obstruction you can now classify it based on the box which we had given those criteria so at this point just remember from this report there was no restriction there was obstruction because the fev1 fvc was less than 70 and even post bronchodilator there was no change they did not go above 70 so there was definitely a obstruction even post bronchodilators was not improving more than 70 percent because of that we obviously see the fev1 and the fpv one is 68 so there is an obstruction further on we have to see the post bronchodilator improvement in the fev 1. now in this the percentage predicted you should see the fev 1 is 68 and then it is becoming 75 percent is predicted in the row of the fev1 post bronchodilator after 68 you go on the right side and you will find 75 so there is a change in the fev1 from 68 to 75 there is a change which is happening definitely it is happening but the change will will be considered as significant or we consider it reversible if this change is more than 12 percent or more than 200 ml okay there there has to be a change more than 12 or more than 200 ml so the further question as to how to calculate the change in ml one is you actually calculated by the values which are given and subtract the pre-bronchodilator actual values and the post bronchodilator actual values or in certain machines like the one which we have shown it here you can see a percentage change coming to 11 just next to 75 you can see 11 percent that means it is less than 12 percent we want the change to be more than 12 percent or more than 200 ml to say that it is a reversible obstructive airway disease and here the change is only 120 ml as you can see the last last column only 1.12 that is 120 ml so there is a definitely lesser change and because it is not more than 12 or more than 200 ml it is called as irreversible airway obstruction okay i don't know if all people are getting it but first we see the fpc next we also see the fev1 upon fvc you need to see the fev1 also you need to see the post bronchodilator fev1 also and then decide or analyze or give a report now let's take another example let's let's me put it this way this is already an answered example but you can still try it so try to see if the interpretation given is correct with what you thought about can you see the fbc so if you have seen the fec in the percentage predicted okay you need to see the percentage predicted column which is one two three four five sixth column from the left in the fvc so 98 percent so the fvc is 98 percent so there is restriction no there is no restriction now you see the fe v1 upon fbc and in that you are going to see the the best of the trials which is given so that is the pre post fe the sorry not the prepos fe 1 fvc ratio which is 59 so 59 means there is definitely a obstructive airway disease okay so if the bronchodilator minus three percent does not mean anything i mean you should not consider it to be that now the bronchodilator is not going to improve or not improve what we are concerned with the post bronchodilator is it going to reverse or not so at this in this spirometry the fev1 up if we see 59 so indicates that there is a obstructive airway disease now you should see the change which is happening so the change happening is that the post bronchodilator fev1 upon fvc is going to 72 can you see it 72 the post bronchodilator fev1 upon fpc is 72 so it means that there is an improvement above 70 and it means that there is a reversibility in the obstruction but is it really confirmed that can be have known only by seeing the fev1 so you see the fev1 and you can see that the predicted is 66 percent it is in the percentage predicted column fev1 percentage predicted it is 66 percent and how much is it happening post bronchodilator the fpv one how much is it improving to from 66 can you read that out yes it has gone to it has improved by 28 percent that means it is from 66 it has gone to 85 so there is a percentage change of 28 and absolute improvement of 480 ml 480 ml so when both are happening means we need for both bronchodilator we need to have both 200 ml improvement and more than 12 percent there has to be both present it is not either or it is both has to be present the post bronchodilator fpv one more than 12 percent and the post bronchodilator fever absolute value more than 200 ml so this indicates that there's a reversibility so this is a reversible obstructive airway disease now let me try this one now i'm not going to say anything i'm going to rest myself for some time and you are going to tell me what this report tells you let's see who can answer this anyone wants to try this okay let's go step by step so let's see what is the fvc percentage predicted in this so the fbc percentage predicted in this is 92 percent okay the percentage predicted fbc and this is 92 that means there is no restriction that is sure there is no restriction now did you all see the fev1 upon fvc so if you have seen the fev1 upon fvc how much is the value in this the fever upon fbc how much is this is it there in this no no it's not it's not 65.5 you see the fev1 upon fvc how much is the value of the fev1 upon fbc yeah it is it is 86.8 yeah it is 86.8 percent the fpv one upon fvc you hope which one you have to see the value of the one here it is underlined actually uh wait wait wait there is a confusion let me see uh sorry sorry sorry sorry there is a bit sorry yeah so this was the slide this is the slide i'm sorry no correct i think someone was answered correctly i only changed the slide earlier to that on the mobile so this is the report sorry this is the report which you need to interpret let's go back to that this report so fvc is 87 so it's normal now let's see the fev1 upon fvc ratio how much is the fpv upon fpc ratio in this 65.5 okay 65.5 perfect so this indicates there is an obstruction happening now you see the post bronchodilator fev1 upon fpc what is happening over here it is 67.9 post bronchodilator fever upon fpc is 67.9 that means it is definitely obstructive it is not improving also so now you need to see the fev1 how much is the fev1 given over here the percentage predicted it is 70. okay it is 70 and then you see the post bronchodilator fev1 it is 76 that means the improvement or percentage change is 9 or only 170 ml so it is nine percent and 170 ml so how do we interpret this will it be a irreversible obstructive airway disease yes so it is going to be a irreversible obstructive airway this is perfect perfect so if you have a patient now let's apply this to our patient that if you have a patient who comes to you saying i am getting this breathlessness for last couple of years and i feel breathless i get cough also i'm not improving i used to smoke long back you know that this could be copd because of his history and because of his available symptoms but when you do a spirometry you find that it is showing irreversible moderate obstructive airway disease so you can actually decide which bronchodilator should be given should we start him on some other oral theophilus is he worsening if you have a spirometry earlier and you find that it is worsening now then it means that whatever inhaler you were giving were not useful okay they are going to be not useful so you can't keep on giving the same inhaler again and again and again so there could be certain things which can be applied when you understand about this report we will just analyze one more repea report let's see if you can check this and tell me what what could be the try to check this individually try to find out so for those who have not been able to uh you know sort of analyze it first you need to see the fvc in the percentage predicted column and here the fpc is 92 percent that means there is no restriction the next thing you should see is the fev1 fvc in the pre-bronchodilator best trial is mentioned here it is 86.8 that means it is about 70 so there is no restriction there is no obstruction so it's a normal lung function test or normal spirometry and i will just put a slide before we try to close this session there are many things beyond i mean i have another 30 slides to show you where we have got flow volume loops and the time and flow and many things are there because spirometry is actually one book which which has been published so if anyone is interested in that book also you may contact richard i haven't spoken to rucha about it but we have got a book on a handbook on lung function test so maybe sometime we will be able to sort of you know distribute that as well but this flow chart is just to summarize uh the few ideas about fev1 and fvc and how to interpret them a little easier way simpler way so compare the fec then you check the fe1 fvc and likely restrict you likely obstruct you how much is the improvement whether there is an improvement in the fb of more than 12 percent and more than 200 ml that will also help you guide through the interpretation of a spirometry and there are things like this which maybe we will have to resort to going on with some another session because it would be in detail and as much important as those values and at the end of it you will actually have a flow volume loop also to be interpreted the spirometry values also to be interpreted and also the small area obstruction the time volume curve so everything will have to come together and then we can check what is called as the spirometry analysis but i think for today this is enough because it will be boomeranging back and forth and back and forth yeah so i think we will stop at that yeah definitely this is a really heavy topic and even after doing it again and again we tend to forget so definitely i guess this is enough for this sunday i am glad you all could join us today and on sunday morning you spend lot of time in learning uh so this is great uh so few of our team members have posted in comments too that you can inspire your peers your colleagues to learn uh so you can share it on social media inspire them invite them and as sir mentioned sir we can definitely do that uh distribution of the book so anyone who is interested he can reach out to us on our social handles and i will see how we can take it forward uh you can just uh reach out to us and then we will take it up i'll discuss it sir thanks a lot sir thank you thank you so much wonderful i'll just stop uh presentation here thank you and thank you so much for your time we will definitely continue this as part two uh whenever you have time so thank you bye-bye everyone

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dr. Salil Bendre

Dr. Salil Bendre

Pulmonologist & Transplant Physician, Nanavati Max Hospital, Global Hospital & Masina Hospital, Mumbai

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dr. Salil Bendre

Dr. Salil Bendre

Pulmonologist & Transplant Physician, Nanavat...

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