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Adv DX Test 2
WilliamWall Adv DX chapt 8 PFT
| Question | Answer |
|---|---|
| How many lung volumes are there | 4 |
| how many lung capacities are there | 4 |
| what are lung volumes | distinc measurements that do not overlap each other |
| what are lung capacities | measurements containing two or more lung volumes |
| what volumes and capacities cannot be measured directly | RV, FRC and TLC |
| how do we measure RV, FRC and TLC | indirectly using helium dilution, nitrogen washout, body plethysmograph or radiologic estimation |
| Calculating TLC | IRV+VT+ERV+RV or VC+RV or IC+FRC |
| Calculating VC | IRV+VT+ERV or IC+ERV or TLC-RV |
| Calculating IC | IRV+VT or TLC-FRC or VC-ERV |
| Calculating FRC | ERV+RV or TLC-IC |
| TLC | total lung capacity, sum of VC and RV, based on age size and gender, increased w/obstructive and decreased with restrictive |
| VC | vital capacity, max exhaled volume after a deep breath (if forced it is called FVC) |
| what is the most important part of the FVC | coaching, bad coaching is bad results |
| the 3 phases of the FRC are | max inspiratory effort, initial expiratory blast, forceful emptying of the lungs |
| why do we not continue coaching and yelling during the forceful emptying portion of the FRC | may lead to airtrapping in obstructive pts |
| can a VC be to high? | no, the higher the better, just to low |
| how does obstructive disease cause a decrease in FRC | by causing a slow rise in the RV |
| IC | inspiratory capacity, measured with spirometer |
| FRC | functional residual capacity, (RV+ERV is FRC) resting volume in lungs following exhalation of VT |
| what volume represents the the force of the expanding chest wall and the contractile rebound of the lung tissue(elastic equilibrium) | FRC |
| what kinds of diseases cause a <FRC | pneumothorax, restrictive diseases, age, obesity |
| what kinds of diseases cause an >FRC | emphysema, any disease that causes a loss of lung tissue, obstruction |
| IRV | inspiratory reserve volume, measured with routine spirometer |
| VT | tidal volume, exhaled or inhaled in each breath, can be reduced in both restrictive or obstr |
| a decrease in VT with no change in RR will result in what | hypoventilation and >CO2 |
| What is the normal RR for a pt with restrictive disease | increased, because VT's are shallow, RR must be increased to proportional to loss of VT |
| SVC | slow vital capacity, test performed by having pt blow everything out slowly after max inspiration, allows for less airtrapping |
| what is the most important measurement for a preop pt | VC, significant reduction in VC indicates pt is at high risk for resp failure after surgery |
| ERV | expiratory reserve volume, (FRC-RV is ERV) max exhaled following passive exhalation, < obesity, poor performance and restrictive (limited clinical use) |
| RV | residual volume, amount left in lung after pt exhales all that is physically possible, < in restrictive and >in obstructive as airtrapping occurs |
| RV/TLC, what percent of TLC is normally RV | 25% |
| RV/VC, what percent of VC is normally RV | 33%, >33% COPD is present |
| What is the significance of a reduced RV/VC | none, there are no clinical states that reduce RV/VC only increase as with COPD (will be in normal range with restrictive disease state) |
| VE | RRxVT, best index of ventilation when used in conjunction with ABG. Should be up with exercise, fever, pain, hypoxia and acidosis |
| What does the expiratory side of the FVC curve provide | contractile state of the airways, FEV1, FEV3, FEF25-75, PEF (peak flow) |
| FEVt | forced expiratory volume timed in liters (t is commonly expressed in .5, 1, 2, 3 seconds) norm is relative to his FVC |
| FEV1 | max forced exhalation during 1st second, best indicator of obstructive disease, reflects the flow in larger airways, best express as a % of FVC (FEV1/FVC is FEV1%), norm is 75% of VC, <in acute or chronic COPD, norm in restrictive |
| FEV3 | looks at the 3 second point on the curve. |
| FEV.5 and FEV1 | used along with FEV200-1200 to assess the flow rates and disorders of the large airways, will be < with airway obstruction |
| FEV% | FEVT/FVC reduced with obstructive disorders |
| FEV1% | 75-85% <65% is is airway obstruction |
| FEV3% | 95% |
| FEF25-75% | sensitivity test expressed in L/sec (measures flow or speed of exhalation), middle 50% of the exhalation (not 50% point but total 50%) and reflects patency of airways, best early indicator of obstructive disease |
| PEF | max flow rate during PFT maneuver, steepest part of FVC, can be measured with spirogram or hand-held device at home or ER. Often used by asthmatics to measure severity of asthma obstruction |
| PEF measurements | <100 L/min is sever obstruction, 100-200 L/min is mod to severe obstruction, >200 is mild |
| Once treatment has been started in an asthma pt, what test can be given to help determine response to TX | PEF |
| spirometer | positive displacement-volume, used to measure volumes and flow rates |
| water-seal spirometer | measures volume and time |
| what is the best indicator of a restrictive disease? | Vital Capacity |
| how do we measure obstructive diseases | flow rates, FEV1, FEF200-1200, FEF25-75, PERF and FVC |
| what is the best indicator of obstructive disease | FEV1 |
| what is the best indicator of large airway obstruction | FEF200-1200 |
| what is the best indicator of a small airway obstruction | FEF 25-75 |
| what is the best indicator of airtrapping | FVC that is smaller than SVC |
| what is a PFT | determines the functional status of the lungs |
| what can PFT's be used for | presence of pulm disease, esp which pts will be harmed by smoking, evaluating pts before surgery, eval effectiveness of therapy, documenting progression of pulm disease, effects of exercise on lung function, measures degree of airway hyper-responsiveness |
| what is bronchoprovocation testing | PFT that measures degree of airway hyper-responsiveness |
| contraindications of PFT's | recent ab, thoracic or eye surgery, hemodynamic instability, symptoms indication acute sever illness, recent hypoptysis, pneumothorax, recent hx of ab thoracic or cerebral aneurysm |
| what tis the most important factor influencing lung size and predicted values | height |
| at what age does a persons lung size begin to shrink | 20yrs |
| what is the primary instrument used in PFT's | spirometer |
| what does a spirometer measure | the lung volume compartments that exchange gas with the atmosphere |
| spirograph | attaches to spirometer to graphically record PFT's |
| spirogram | the graphic tracing of the PFT |
| body plethysmograph | for total lung capacity and airway resistance studies |
| what are the 2 main categories of PFT abnormalities | obstructive and restrictive defects |
| how do obstructive disease present on PFT's | if expiratory flow is below normal |
| how do restrictive diseases present on PFT's | if lung volume is reduced |
| Upper airway obstruction will show up where on PFT | reduced flow rate in initial 25% of FEC |
| what portion of the flow/volume curve is effort Dependant | the first 1/3 |
| what portion of the flow/volume curve is effort independent | the later 2/3 |
| a restrictive disease is present when PFT | lung volumes are reduced to less than 80% of predicted levels |
| what are the two most common causes of restrictive disease | atelectasis and obesity |
| what are two examples of combined obstructive/restrictive disease | sarcoidosis and emphysema |
| sarcoidosis | unknown cause characterized by deposition of cicronodules called noncaseating granulomas throughout the body and lungs |
| what is the easiest way to distinguish between obstructive and restrictive diseases on a PFT | obstructive causes reduced expiratory flows, restrictive causes reduced lung volumes |
| 3 ways to measure TLC | body plethysmograph (body box), open-circuit nitrogen washout, or closed-circuit helium dilution |
| why is body box more accurate | it measures communicating and non-communicating/poor communicating spaces (volumes) |
| what are non communicating or poor communicating lung volumes | airtrapping (COPD, Asthma) or pneumothorax |
| (open-circuit) nitrogen washout | air in lungs is 79% nitrogen just like atmosphere, pt breaths 100% O2 for approx 7 mins, nitrogen is measured during exhalation for volume measurements |
| (closed-circuit) helium dilution | pt breaths helium for 7 minutes, when equilibrium is reached, helium is measured and lung volumes are calculated |
| why is helium used as a measuring gas | helium is an inert gas so not significantly absorbed |
| what PFT equipment uses an open-circuit system | nitrogen washout |
| what PFT equipment uses a closed-circuit system | helium dilution |
| what is the most accurate determination of gas volumes in the chest | plethsmograph/body box |
| MVV, max voluntary vent | rapid & full as possible for 12-15 seconds, total exhaled is obtained,repeat 4 or 5 times and multiplied to get a max volume for 1 minute (15x4 is 60), measures status of resp muscles, compliance and resistance, used prior to surgery, not generally useful |
| Flow volume loops (FLOOP) | flow and volume on a graph paper, V is horizontal, F is vertical, Inspiration is below horizontal, expiratory is above |
| how are FLOOPs used to show if response to medications | two flow volume curves superimposed on each other, one before bronchodilator and one after |
| FLOOPs are best used to look for patterns in what diseases | restrictive (<volume), large airway obstruction (<flow, norm volume), severe COPD (hockey stick or boot) |
| PFT's before and after bronchodilator | 2 of 3 must improve, FVC >10%, FEV1 15%, or FEV25-75 20-30%, best in asthmatics, misleading in COPD |
| DLCO | diffusion capacity of the lungs, <with emphysema and pulm fibrosis |
| RAW | normal w/out ETT tube .5-3.0 cmH2O/L/sec, as airways narrow, pressure of resistance increases |
| compliance | volume change per unit of pressure change, measured with balloon catheter |
| Dynamic compliance | measured when gas is flowing |
| static compliance | measured with no flow of gas |
| Total CL | lung tissue compliance + chest wall compliance, <CL as lungs become stiff, the more non-compliant the more stiff, |
| what is a flat top of the curve represent on a floop | stiff lungs-<CL, (less volume, more pressure) |
| what does a round top of the curve represent on the floop | emphysema, <elastance (more volume and less press) |
| RQ | respiratory quotient, norm is .8-.85, ratio of CO2 produced to O2 consumed. Fatty diet RQ is .7 and RQ is 1 for carbs, best used during weaning to adjust pt diet and <WOB |
| Bronchoprovocation | pt inhales histamine or methacholine, cold air and exercise, used to test pt for hyperactive airways |
| methacholine challenge | parasympathomimetic used to induce bronchospasm |
| most useful PFT tests as seen in table 8-1 | 1-VC, 2-FEV1 and FEV1%, 3-TLC, FRC, RV, RR, VE, FEV3, FEV25-75, DLCO, RAW and CL |
| Do PFT's measure the ability of the lungs to exchange resp gases | no, DLCO does and it is done in a closed circuit helium test with carbon monoxide |
| which of the following is least use PFT-A)documenting disease progression B) eval probability of getting a pulm disease C) exercise eval D) weaning from mech ventilation | B is |
| The tracing obtained from a PFT is called | spirogram |
| which is the most important factor in predicting PFT measurement age, weight, height, gender | height |
| PFT's are effort dependent T/F | True |
| What piece of equip is used to measure TLC and RAW | body plethysmography |
| which of the following are consistent with obstructive disease? > exp flows, <exp flows, <vol and flows, or >volumes and flows | <exp flow |
| an obstruction in the upper airway will affect which portion of the spirometric tracing | all of it, the initial the middle and the end, it is flat |
| which is true regarding restrictive disease-<volumes on PFT, can be caused by obesity, exp flow are usually normal | all (not sure on the flow) |
| VT can be > or < with restrictive or obstructive disease | VT is < with both restrictive and obstructive |
| what PFT is useful in determining the need for mech ventilation | FVC |
Created by:
williamwallace
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