lung sounds - semantic scholar · 2017. 11. 29. · sounds transmitted through the lung & chest...
TRANSCRIPT
![Page 1: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/1.jpg)
LUNG SOUNDSLUNG SOUNDS
![Page 2: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/2.jpg)
![Page 3: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/3.jpg)
![Page 4: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/4.jpg)
• Bronchus lumen that air has to pass away
![Page 5: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/5.jpg)
Normal Sound = Normal Sound = Breath SoundBreath Sound
• Produced by TURBULENT FLOW in the larger airways creates audible vibrations in the airways producing sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation (diff between bronchial & Vesicular)
![Page 6: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/6.jpg)
![Page 7: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/7.jpg)
Auscultation of the lung• listening for sounds produced in the lung
to identify normal or abnormal lung sounds• a stethoscope is designed for better
transmission of sounds to the examiner• the room should be quite• vesicular or normal, bronchovesicular,
tracheal, bronchial
![Page 8: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/8.jpg)
![Page 9: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/9.jpg)
![Page 10: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/10.jpg)
ABNORMAL Breath Sounds
BRONCHIAL • The Lung Increases in density
(Pneumonia, atelectasis) : Vesicular Bronchial
• Normal air filled lung becomes Consolidated Attenuation reduced similar sound (upper large airways & Consolidated lung)
![Page 11: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/11.jpg)
Abnormal Breath SoundsDiminished Breath sounds• Intensity of sound at the site of generation
(larger airways) is reduced . Ex : shallow or slow breathing pattern
• Increase Attenuation. Ex: Hyper inflated lung tissue, Obstructed airways (mucus plug)
• Reduce transmission of breath sounds through the chest wall. Ex : Air or fluid in pleural space, obesity
![Page 12: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/12.jpg)
Characteristic of Normal Breath Characteristic of Normal Breath SoundsSounds
Breath Sound Pitch Intensity LocationDiagram
Vesicular/normal Low Soft Peripheral Lung
Bronchovesicular Mod Mod Around upper part of Sternum,between Scapular
Tracheal High Loud Over Trachea
![Page 13: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/13.jpg)
![Page 14: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/14.jpg)
A. Anterior Bronchovesicular
B. Posterior Bronchovesicular
C. Anterior VesicularD. Posterior Vesicular
![Page 15: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/15.jpg)
![Page 16: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/16.jpg)
![Page 17: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/17.jpg)
Auscultation of the lungs
Adventitious sounds: abnormal lung sounds superimposed on normal Sounds
**discontinuous: cracles** continuous: wheeze , stridor, ronchi
(low pitch wheeze)
![Page 18: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/18.jpg)
![Page 19: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/19.jpg)
![Page 20: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/20.jpg)
WheezingWheezing
• Continuous ALS, easy recognized• Generated by
Vibration of the Walls of Narrowed or Compressed airway as air passed through at high velocity
• The pitch of Wheeze independent of the length of the airway BUT related directly to the degree of airway compression.
• The tighter compression the higher of the pitch
![Page 21: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/21.jpg)
• Airway diameter reduced may be caused byBronchospasm, mucosal edema, foreign object, compression extra lumen.
![Page 22: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/22.jpg)
Wheezing• When Wheeze identified Note : pitch, intensity,
the portion of respiratory cycle occupied by wheezing
• >> Narrowing ↑ ↑ pitch, >> intensity (louder) and > in portion of respiratory cycle occupied (inspiration & expiration).
• Improvement airway caliber ↓ pitch, < intensity, < respiratory cycle occupied (expiration only)
![Page 23: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/23.jpg)
STRIDOR• Life threatening sign• Mechanism = > to WHEEZING
Rapid airflow through a Narrow site of upper airway produce Vibration of lateral walls ↑ ↑ pitch sound, often heard without stethoscope
• Narrowed upper airways may be caused by infection (croup, epiglotitis), inflammation following extubation
![Page 24: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/24.jpg)
STRIDOR
• Most often heard during inhalation because :Upper airway tends to narrow with significant inspiratory efforts
• When severe obstruction & fixed ( airway opening not vary with breathing) Stridor Inspiratory & Expiratory
![Page 25: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/25.jpg)
Continuous ALS, Low pitched
• Ronchi = Ronchus (Ronki kering )
• Low pitched continuous sounds associated with Presence excessive sputum in the airways A sputum flap vibrating in the airstream low pitched wheezes , clear after patient cough
![Page 26: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/26.jpg)
CRACKLESCRACKLES• Discontinuous ALS• Produced by movement of excessive secretions
or fluid in the airways as air passes through Coarse crackles, heard during Inspiration and expiration. Often clear if the patient cough
• Crackles : without excessive secretions , but collapsed airways pop open during inspiration Produce explosive equalization of pressure between collapse & patent airways.Airway closure may occur in peripheral bronchioles or more proximal bronchi
![Page 27: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/27.jpg)
....CRACKLES
• Crackles in Early inspiratory :larger, more proximal bronchi close during expiration (caused by ↑ bronchial compliance or low retractive pressure around the bronchi) ex in COPD, asthma , emphysenma
![Page 28: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/28.jpg)
CRACKLES• Crackles occur late in inspiratory phase :
Peripheral alveoli & airways close during exhalation caused by ↑ surrounding intrathorax pressure. Crackles produced by sudden opening of periphearl airways ussualy occurs late in inspiration phase.May clear with changes posture, or several deep inspiration. Coughing or maximal exhalation produce reappearance of late inspiratory cracklesEx. Pulmonary edema, fibrosis that reduce lung volume, atelectasis, pneumonia
![Page 29: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/29.jpg)
Mechanism of Late inspiratory Crackles.Peripheral airways pop open when inspiratory effort is sufficient to overcome the forces causing the atelectasis
![Page 30: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/30.jpg)
PLEURAL FRICTION RUB• Creaking or grating type of sound, occurs when
pleural surfaces become inflamed and the roughened edges rub together during breathing
• May be heard during inhalation only but often in both (Inspiratory & Expiratory)
• Sound similar to Coarse crackles BUT not affected by coughing
• Intensity of pleural rubs may ↑ when deep breathing
![Page 31: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/31.jpg)
![Page 32: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/32.jpg)
![Page 33: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/33.jpg)
Adventitious Lung Sounds (ALS)
-Continuous (continuous sounds)
-Discontinuous(intermittent, crackling, bubbling sound , short
duration)
![Page 34: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/34.jpg)
WheezingWheezing
• Continuous ALS, easy recognized• Generated by Vibration of the Walls of
Narrowed or Compressed airway as air passed through at high velocity
• The pitch of Wheeze independent of the length of the airway BUT related directly to the degree of airway compression.
• The tighter compression the higher of the pitch
![Page 35: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/35.jpg)
• Airway diameter reduced may be caused byBronchospasm, mucosal edema, foreign object, compression extra lumen.
![Page 36: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/36.jpg)
Wheezing• When Wheeze identified, Note : The pitch,
Intensity, the portion of respiratory cycle occupied by wheezing
• More Narrowed airway caliber higher pitch, increase intensity (louder) and increase in the portion of respiratory cycle occupied (inspiration & expiration).
• Improvement airway caliber (ex. by treatment), decrease pitch, decrease intensity, decrease respiratory cycle occupied (expiration only)
![Page 37: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/37.jpg)
STRIDOR• Life threatening sign• Mechanism similar to WHEEZES Rapid airflow through a Narrow site of upper airway produce Vibration of lateral walls High pitch sound, often heard without stethoscope
• Narrowed upper airways may be caused by infection (croup, epiglottitis), inflammation following extubation
![Page 38: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/38.jpg)
STRIDOR
• Most often heard during inhalation because :Upper airway tends to narrow with significant inspiratory efforts.
• Stridor Inspir & Expir : When severe obstruction and fixed ( airway opening not vary with breathing)
![Page 39: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/39.jpg)
Continuous ALS, Low pitched
• Ronchi = Ronchus (Ronki kering ?)
• Low pitched continuous sounds associated with Presence excessive sputum in the airways A sputum flap vibrating in the airstream low pitched wheezes , clear after patient cough
![Page 40: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/40.jpg)
CRACKLESCRACKLES• Discontinuous ALS• Produced by movement of excessive secretions
or fluid in the airways as air passes through Coarse crackles, heard during Inspiration and expiration. Often clear if the patient cough
• Crackles : without excessive secretions , but collapsed airways pop open during inspiration Produce explosive equalization of pressure between collapse & patent airways.Airway closure may occur in peripheral bronchioles or more proximal bronchi
![Page 41: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/41.jpg)
CRACKLES
• Crackles in Early inspiratory :larger, more proximal bronchi close during expiration (caused by ↑ bronchial compliance or low retractive pressure around the bronchi) ex in COPD, asthma , emphysenma
![Page 42: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/42.jpg)
CRACKLES• Crackles occur late in inspiratory phase :
Peripheral alveoli & airways close during exhalation caused by ↑ surrounding intrathorax pressure. Crackles produced by sudden opening of periphearl airways ussualy occurs late in inspiration phase.May clear with changes posture, or several deep inspiration. Coughing or maximal exhalation produce reappearance of late inspiratory cracklesEx. Pulmonary edema, fibrosis that reduve lung volume, atelectasis, pneumonia
![Page 43: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/43.jpg)
Mechanism of Late inspiratory Crackles.Peripheral airways pop open when inspiratory effort is sufficient to overcome the forces causing the atelectasis
![Page 44: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/44.jpg)
PLEURAL FRICTION RUB• Creaking or grating type of sound, occurs when
pleural surfaces become inflamed and the roughened edges rub together during breathing
• May be heard during inhalation only but often in both (Insp & Exp)
• Sound similar to Coarse crackles BUT not affected by coughing
• Intensity of pleural rubs may ↑ when deep breathing
![Page 45: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/45.jpg)
Recommended Terminology for Lung sounds
Recommended Term Classification Other Term used
Crackles Discontinuous RalesCrepitations
Wheezes High-pitched Sibilant ralesContinuous Musical rales
Sibilant ronchus
Low-pitched Sonorous ralesContinuous Rhonchi
INDO : Ronki kering
![Page 46: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/46.jpg)
![Page 47: LUNG SOUNDS - Semantic Scholar · 2017. 11. 29. · sounds transmitted through the lung & Chest wall it is altered by Normal lung (normal lung tissue act as low-pass filter Attenuation](https://reader035.vdocuments.mx/reader035/viewer/2022071107/5fe1e11889ab6516e370f381/html5/thumbnails/47.jpg)