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Pulmonary Embryology
• Notochord develops in the 3rd week of gestation
• Brain develops in the 8th week of gestation
• 12th week of gestation the other organ systems begin to form
• Lung develops in 1st trimester
- • It is derived from the Foregut
- • From the lip → 2nd part of the duodenum, including the respiratory tract = FOREGUT
• Surfactant is not completely made until 32-34 wks.
- • Lecithin Sphigomyelin ratio is 2:1 to indicate maturity
- • < 2/1 = ↓ in surfactant → immature
- • Beclamethasone → (+) surfactant production
- • If preterm labor w respiratory distress → give synthetic surfactant via endotracheal tube → ↓ mortality
- • > 2/1 = ↑ in surfactant → enough for labor = mature lungs
- • Check for Phosphatidylglycerol →breakdown product of surfactant
- • Function
- • Surfactant acts as an oil
- • Main job is to decrease surface tension of alveoli → prevents collapse by keeping the alveoli open
- • If no sufactant → Atelectasis = collapse of the alveoli
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Atelectasis
• Diffusion problem
• Collapsed alveoli → no oxygen exchange → Respiratory Distress Syndrome = Pulmonary distress in a Premature Baby:
- • When a premature baby is born he goes into respiratory distress until his alveoli pop open.
- • Need to give baby Oxygen to create a concetnration gradient that will allow Oxygen to get into the lungs.
- • More O2= more free radical formation → lungs undergo metaplasia and will form a hyalin membrane
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Hyaline Membrane Disease
• Induced by giving O2 to a baby who is hypoxic due to atelectasis.
• Try to figure blood gasses:
- • ↓pO2 will cause
- • ↑respiration → ↓pCO2
- • ↑pH
• Restrictive lung disease
- • Need to put baby on a ventilator, PEEP/CPAP
- • This provides a positive airway pressure to keep the alveoli open → gives some RV
- • Complicaton: bilateral pneumothorax because of the increased pressure required to infuse the oxygen
- • Will need chest tube.
- • The free radicals made by oxygen will irritate the airway and stimulates mucous production
- • Goblet cell hyperplasia and hypertrophy
- • Narrow airway lumen = Obstructive lung disease → Bronchopulmonary dysplasia (abnormal growth)
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Bronchopulmonary Dysplasia
• common complication of Hyalin membrane disease
• obstructive lung disease
• Acts like asthma
• Treated the same
• Majority of children will outgrow O2 by age 2 (when their lungs are almost adult size)
• Will continue to have obstructive airway disease for the rest of their lives.
• Artifical surfactant is used to ↓ need for O2 and hospitalization
• 1st give mother beclamethasone to ↑ baby’s own surgactant production
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Adult disease
• ARDS –
- • Most common cause
- • Sepsis
- • Will need intubation and ICU
- • Will have same disease course and complications as child
- • 60% mortality rate
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Aspiration Pneumonia
• Most commonly involves the Right main stem bronchus & straight down into the right lower lobe
• If the kid is standing/sitting upright and aspirates, it will go straight down to the superior segment of the R lower lobe
• If the kid is laying down it will enter the posterior segment of the right lower lobe
• Only way to aspirate into the upper lobes is to aspirate the foreign body while lying down on their side
• Usually a seizure patient
• Always look for foreign body in recurrent R upper lobe pneumonia
• Diagnosis
- • Need to get Inspiratory/expiratory films
- • On inspiration everything inflates
- • On expiration one bronchus remains inflated
• Removal
- • For a child the best way is to lay them on their stomach and performa back thrust
- • For an adult → Heimliech Manuver
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3 Narrowings of the Trachea where objects get lodged
• Glottis
• Middle of the trachea (landmark → aortic arch)
• Bifuraction of the Trachea at T4
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Restrictive and Obstructive pattern
• MCC of Death → Bronchiectasis
• bronchi are thickened from inflammation and infection
• Restrictive Disease = problem in the interstitium
- • O2 diffusion will be affected the most
- • diffusion and perfusion limited
- • CO2 diffuses fast so it is airway limited
- • airway problems, ventilation problems
- • signs of :dyspnea(SOB), and tachypnea(rapid breathing)
- • ↓pO2 ↓pCO2 ↑pH
• Obstructive Disease = caused by Bacteria producing mucus in Airway
- • increased respiratory rate of dyspnea and tachypnea
- • normal pO2 ↑pCO2 ↓pH
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Amnionic Fluid
• Function:
- • Create negative pressure around the fetus and absorbs external trauma to the mother’s abdomen
- • In order for the lungs to inflate in the baby you need negative pressure within the amnionic sac.
- • Amnionic fluid is there to keep pressure off of the baby while the negative pressure inflate the lungs
• Composition
- • 80% is filtrate of mom’s plasma
- • Baby must be able to Swallow & digest → then process → adds 20% to it then urinates in the amniotic sac
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Polyhydramnios
• baby can’t swallow or absorb fluid (neurological, muscular problem, GI obstruction)
• Mom continues to make 80% of the amniotic fluid but the baby isn’t swallowing it = the baby has a Neuromuscular disease (swallowing is a reflex) or GI obstruction
• Think of Werdnig – Hoffman Syndrome
• Duodenal or esophageal Atresias can present this way.
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Oligohyramnios
• Low amnionic fluid
• Baby has renal defect (agenesis/obstruction) and can’t pee → can’t add 20%
- • Will cause increased pressure on the baby because there is no Amnionic fluid to protect the baby from any trauma
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• Potter’s syndrome
- • See the physical manifestation of oligohydramnios
- • ↑atmospheric pressure will cause facial deformity and baby’s facial features to be flattened (due to pressure) = smashed face
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Prune Belly
• No Abdominal wall muscles, therefore can’t bear down to pee, so there is no muscle to push fluid out creating pressure and a prune like appearance in baby
• This baby will dies of infections (UTI) because always has a catheter
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Anatomy of the Lungs
• Extrathoracic (outside chest cavity) and intrathoracic (inside chest cavity) are separated by glottis.
• Breath in → Extrathoracic collapses and intrathoracic expands
• Breath Out → Extrathoracic expands and intrathoracic narrows
• Main stem Bronchus
- • Breaks into parenchyma ½ way and gets smaller
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• After Main stain bronchi will divide into
- • large
- • medium
- • small bronchioles
• Terminal Bronchiole
- • Most dependent part of airway → therefore, most Lung Cancers like to form here
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• Will deposit in the terminal Respiratory bronchiole
- • Respiratory unit = the only 3 units where O2 Exchange occurs
- • Resp bronchiole
- • Alveolus
- • Alveolar duct
- • made of 1 layer of epithelium
- • Can have O2
• Physiologic Dead Space
- • Composed of all CO2
- • Taking a deep breath can clean out the dead space
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Ventilation
• Total ventilation = ventilation dead space + ventilation alveolar
- • TV = VDead Space + VAlveolar
- • VMinimum = TV x RR
- • Tidal Volume = 10 – 15 cc/kg
- • Example:
- • TV = 600 cc
- • RR = 12
- • VDS = 40%
- • What is the ventilation in the alveoli?
• The true measure of ventilation is in the pCO2 changes
- • If truly ventilating the pCO2 will drop
- • Patients presenting with SOB/tachypnea are not ventilating properly
• 500 cc is not universal!!!
• One can be breathing fast (tachypnic) but not ventilating properly!!!
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Chest Cavity
• Diaphragm normally develops Ventral (midline) → Dorsal (back)
• Diaphragmatic hernia=
- • Intestines are in thoracic cavity
- • Present with bowel sounds in the chest cavity
- • See a feeding tube curled into his chest on x-ray
- • Common types:
- • Bochtalek (90%)
- • Herniation is in the back
- • Morgagni (10%)
- • Herniation is in the front/mid-line
- • Complication
- • The lung won’t develop because the GI/Intestines are pushing down on the lungs and can’t inflate à pulmonary hypoplasia
- • Next step is to try and close the hole
- • Need at least 90% of the lung to develop in order to live.
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Lung Histology
• Trachea :
- • Top 1/3 = Squamous cells (protect against abrasion)
- • Middle 1/3 = Transition cells
- • Lower 1/3 = short colunmnar epitherlium
- • Beat upward → to swallow foreign debris and let stomach acid digest it
• Respiratory Epithelium
- • Tall columnar ciliated epithelium (bottom 1/3 and into bronchus)
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• Cilia
- • 9+2 (actin microtubules) configuration =
- • 9 microtubules surrounding 2 actin proteins)
- • Need a Dynein arm to have flexibility
• Dynein arm
- • Allow cilia to dissengage from mucus and push it forward to move it always is only one direction → toward the mouth → orad movement
- • When cough, mucus moves 1”/ cough
- • Sinus drainage → short cough
- • Bronchitis → deeper cough...
- • Also needed in sperm
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Kartagner’s Syndrome
• Defect of the Dynein Arm →not working = Can’t clear mucus
• Triad
- • Obstruction → Bronchiectasis
- • Infertility → because sperm are immotile
- • Situs inversus (liver/ kidney on other side= midgut rotation)
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Common bacteria in the back of the throat
• Strep Pyogenes
•S pneumonia - encapsulated
• H influenza - encapsulated
• Neisseria Cataralis - encapsulated
- • These bacteria can live in the back of throat because they contain IgA Protease to protect against IgA activity
- • Therefore, they are the MCC of sinusitis, otitis, bronchitis, and pneumonia
• Cilia prevents these bacteria from entering the lung but if the cilia is paralyzed they can enter
- • Viral infections can paralyze cilia and allow for the encapsulated organisms to come into the lung = SUPER – INFECTION
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Cell type
• Goblet cells:
- • Most numerous
- • serve to produce mucus
• Type I pneumocytes (95%) –
- • mostly macrophages
- • Found mostly in terminal bronchus where all the dust will settle
• Type II (5%) pneumocytes
- • produce surfactant
- • Found in alveoli, surrounding alveolar membrane
- • Can become type I, but can’t go the other way round. (Type I can not become Type II
• Dust/ Clara Cells
- • macrophages that ingest dust particles
- • found in terminal bronchus
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Smooth Muscle
• found throughout airway down to terminal bronchiole
• Can’t have anything in the way of O2 diffusion – so will stop in terminal bronchiole
• Most abundant in medium size bronchioles
- • Therefore, the most constriction and dilatation occurs here
- • analogous to blood vessels (contain the most β2 receptors)
- • Asthma is a small airway disease but the wheezing is coming from the Medium bronchioles
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Cartilage
• Tracheal and Laryngeal cartilage is of neural crest origin (septum)
• Trachea has 16-20 C shaped cartilage rings
• Why C-Shape: Opening always faces backwards so esophagus, when full can compress trachea so you are less likely to aspirate.
• Mid main stem bronchus – start fully circling cartilage
• Because of the lung tissue all around it, if it where not fully encircled it would collapse
• Stops at the Respiratory unit to allow for diffusion
• Terminal Bronchiole – end of cartilage (because has to be only one layer of cells)
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Lung Sounds
• Stridor: narrowing in extrathoracic airway
- Inspiratory sound only
- Problem is from Lip to the glottis
- need a lateral neck film
- Macroglossia (big tongue)
- storage disease
- hypothyroidism
- Down’s
- 2nd Brachial Arch problem è microagnathia (small jaw)
- Pierre-Robin
- Treacher Collins
• Wheeze: narrowing in intrathoracic airway
• Rhonchi: air moving over mucus
• Crackles: collapsed airways “popping” open
- • Surfactant is missing
- • Alveoli have been scarred down
• Decreased breath sounds: space between alveolus and chest wall is occupied
• Dullness to percussion: as above
• Increased fremitus: consolidation on same side or atelectasis on opposite side
• Bronchophony, egophony, or "ee" to "aa" changes: as above
• Tracheal deviation: towards atelectasis and away from a pneumothorax
• Hyperresonance: pneumothorax on same side or atelectasis on opposite side
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Lung Infections
• Croup
• Bronchiolitis
• Bronchitis
• Pneumonia
• tracheitis
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Croup
• Subglottic edema similar to bronchilitis.
• Presentation
- • Barking cough and Stridor
- • Steeple sign on neck X-ray
• Caused by:
- • Parainfluenze
- • RSV (send to ER immediately)
- • Adenovirus
- • Influenza
• Treatment
• Dexamethasone
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Bronchiolitis
• Infectious asthma
• Includes all symptoms of asthma with acute infection
• MC in children < 2 years old → can be able to grow out of it
• Caused by:
- • Parainfluenze
- • RSV (send to ER immediately)
- • Adenovirus
- • Influenza
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Bronchitis
• URI (Upper Respiratory Infection)
• Acute = ↑ sputem production
• Chonic = ↑ mucous production for at least 3 consecutive months for 2 consecutive years
• MCC:
- • pneumo.
- • influenza
- • Catarallis
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Airway Infections
• Epiglotitis: H. Influenza B
• Tracheitis: C. Diptheria
• Pneumonia
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Epiglotitis
• closure of trachea
• Presentation
• Child will be drooling, stridor, muffled voice and fever
• MCC → H. influenza B
• Treatment
- • Must make an airway → Intubate in the ER
- • Look for thumb sign on CXR
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Tracheitis
MCC → Diptheria → EF-2 ribosylation = gray pseudomembrane
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Tracheomalacia
Stridor since birth
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Pneumonia
• Inflammation in the alveolus
• MCC
- • Strep pneumonia: Rusty colored sputum
- • H flu: Staph Aureus
- • Neisseria
- • Klebsiella → currant jelly sputem, homeless alcoholic; likes fissures of lung
- • Common after flu → S. aureus
- • Actinomyces → sulfur granules
- • S aureus and pseudomonas → bullae production d/t elastase activity (pneumatocelle)
- • Anaerobic infection – foul smelling; (+) air/fluid levels, gas formation
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Interstitial Pneumonias
• Atypicals
• Fungus
• Pneumoconioses
• Nocardia
• Sarcoidosis
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Atypicals
• Chlamydia: from 0 to 2 mo
• Mycoplasma: from 10 to 30 y/o
• Legionella: over 40 y/o
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Fungus
• Histoplasmosis: midwest
• Blastomycosis: northeast
• Coccidiomycosis: southwest
• Paracoccidiomycosis: South America
• Aspergillus: moldy hay or moldy basement
• Sporothrix: rose thorn
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Pneumoconioses
• Asbestosis
• Silicosis
• Bissinosis
• berrylliosis
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Nocardia
the only G+ that is partially acid fast
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Sarcoidosis
• noncaseating granulomas; large hilar adenopathy; high ACE levels
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Respiratory Infections (others)
• Asthma
- • Intrinsic
- • Congenital
- • Cold air/Colds set this off
- • Extrinsic
- • Environmental
- • Offending agents
- • Dust mites >> Roach droppings >> Pet Dander
• Emphysema
- • Digestion of interstitium by elastase
- • Treat as an OBSTRUCTIVE disease but really is a restrictive disease
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Lung Cancers
• MC intrathoracic = Squamous cell → PTH secretion
• Small Cell Carcinoma
- • Anaplastic• Located at the carina• Produces 4 hormones:
• ACTH: 90% • ADH: 5% • PTH: 3% • TSH: 2%
• MC Primary Lung CA → Bronchogenic Adenocarcinoma
• Most common lung mass in children is: Hamartoma
• Most common lung mass in adults is: Granuloma
• Most common TUMOR: adenoma
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Physiologic parts to the lung
• Intrathoracic space
- • Chest wall
- • Pleural space
• Pulmonary vasculature
• Pulmonary airway
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Lung Volumes
• RV:
- • Residual volume
- • the amount of air left in the lungs AFTER forced expiration
- • Can not be physiologically forced out
- • Maintains some compliance in the airway
- • Keeps alveoli from collapsing
• ERV:
- • Expiratory reserve volume
- • the amount of air that can still be FORCED out AFTER a normal exhalation
- • Fills up the dead space at rest; decreases the tidal volume that you would have to take in
• FRC:
- • functional residual capacity
- • FRC = RV + ERV
• TV:
- • Tidal volume
- • the amount of air you take IN during a NORMAL inhalation effort
- • 10 – 15 cc/kg
• IRV:
- • inspiratory reserve volume
- • the amount of air you can FORCE INSPIRE after a normal inhalation effort
• TLC:
- • Total lung cap
- • ALL the air in your lungs at the END of a deep breath
- • RV + ERV +TV + IRV
• VC:
- • Volume cap
- • all the air you can breathe in AFTER forced exhalation
- • ERV + TV + IRV
• Obstructive Disease
- • RV changes 1st = ↓
- • In both TV changes last
• Restrictive Disease
- • VC drops 1st; TLC drops next
- • In both TV changes last
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Inspiration
• Beginning: expansile forces of the CHEST WALL is greater ( 0 to 49%)
• Middle: expansile forces of the LUNG is greater ( 50 to 99%)
• End: recoil force of the chest wall EQUALS the expansile force of the lung
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Expiration
• Beginning: recoil forces of the CHEST WALL are greater ( 0 to 49%)
• Middle: recoil forces of the LUNG are greater ( 50 to 99%)
• End: the recoil force of the lung EQUALS the expansile force of the chest wall
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Breathing in…
• FRC: baseline > intrathoraxic pressure is negative ( - 3 to – 5)
• TV: intrathoraxic pressure gets more negative ( -10 to -12)
• TLC: intrathoraxic pressure most negative (-20 to -25)
• Intrathoraxic Pressure should always be NEGATIVE
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Intrathoraxic Pressure
• Should ALWAYS remain negative
• Should decrease with inspiration
• If it gets positive, then it will resist any blood or air from entering the thorax
• If you do not breathe in, there will be NO pressure gradient for blood to enter the thorax
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Positive Intrathoracic Pressure
• Kussmaul sign: increased JVD with inspiration
• Pulsus paradoxicus: exaggerated drop in BP( more than 10mmHg) or pulse ( more than 10bpm) on inspiration
• Mcc: pericardial tamponade or pneumothorax
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Pericardial Tamponade
• is when fluid in the pericardium builds up
• if equal pressure on both sides of chest
• Mcc: trauma or cancer
• CXR: enlarged cardiac shadow
• ECHO: compressed small heart
• Tx: pericardiocentesis
• If recurrent: put in a pericardial window
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Pneumothorax
• if NOT equal pressure on both sides of chest
• Traumatic
• Spontaneous
- • Associated with estrogen use or collagen disease
- • Less than 25% occupation & asymptomatic
- • More than 25% occupation or symptomatic
• Tx: chest tube placement
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Flow ( Q )
• As you breathe in, the lung Inflates, pulling on traction fibers attached to vessels
• As vessels DILATE, flow increases
• As flow increases, oxygen dilates the vessels, significantly increasing Q
• The increased Q keeps the pulmonary valve open longer, INCREASING S-2 splitting
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Flow ( Q ) is greater to the bottom of the lungs because…
• (1) gravity
• (2) less resistance
• (3) more oxygen goes to the bottom of the lungs with each breath
• Normal RR = 12 to 16 breaths/min
• Q increases on inspiration and decreases on expiration.
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S-2 Splitting
• It is caused when the closure of the aortic valve (A2) and the closure of the pulmonary valve (P2) are not synchronized during inspiration
• Increases on inspiration due to Increased pulmonary blood flow
• Decreases on expiration due to decreased pulmonary blood flow
• This is why RIGHT sided heart sounds increase on INSPIRATION
• This is why LEFT sided heart sounds increase on EXPIRATION
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Oxygenation
• Directly related to DIFFUSION and PERFUSION
• More oxygenation is accomplished at the bottom of the lungs only on inspiration
• Most of oxygenation is accomplished at the top of the lungs > ALWAYS OPEN!
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Ventilation (V)
• Inversely related to pCO-2
• Definition: patent airway
• Measurement: pCO-2 ( on ABG’s)
• More V to the bottom of the lungs only on inspiration
• Most V at the top of the lungs because it is ALWAYS PATENT
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The Law of V / Q
• V /Q is greatest at the top of the lungs, equally matched in the middle, least at the bottom
• If you change one, you MUST change the other in the SAME direction
• ANY V / Q mismatch will lead to hypoxia
• Eisenmeger Syndrome
- • Pulmonary HTN that reverses blood flow
- • Rx: Nitrous Oxide → dilates pulmonary vessels
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Pulmonary Airway Pressure
• The Only Pressure That Gets Positive With Each Breath
• Pa = Patm at IRV and FRC
• Pa < Patm at inspiration
• Pa = Patm at end of deep breath
• Pa > Patm at expiration
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Compliance
• ability to distend and increase volume
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V/Q mismatch
• Black = normal
• Red = obstructive leaving air inside
• Blue = emphysema, trouble breathing in and breathing out. (obstruction)
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Respiration Bodies
• Carotid Body
- • located at the bifurcation of the internal and external carotids
- • Measures PO2, PCO2, pH, and H+ ions
- • Afferent (CN IX) and Efferent (CN X)
• AORTIC BODY
- • found in the arch of the aorta
- • Measures pCO-2, pH, and H+ ions
- • Afferent and Efferent are both CN X
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Signals from the lungs and chest wall
• J-receptors: found in the interstitium of lungs
- • Senses interstitial particles
- • Increases respiratory rate (Tachypnea)
• Slow adapting receptors: found in the ribs,especially the sternocostal junctions
- • Senses stretch and inflation of ribs
- • Causes exhalation
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Sinuses
• Maxillary
• Ethmoid
• Sphenoidal
• Frontal
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BRAIN IN RESPIRATION
• More sensitive to elevated pCO-2
• Hypoxia and Hypercarbia (abnormally elevated CO 2) are synergistic
• Forms of pCO-2:
- • regulated in pons
- • 90% in the form of HCO-3 (acid)
- • ↑HCO3 → metabolic alkalosis → low vol state
- • ↑pCO2 detected by pneumatic center
- • if u give O2 it will knock out apneustic center and kill the patient
- • 7% as carbaminohemoglobin and carboxyhemoglobin
- • 3% is dissolved ( .03pCO2 )
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Pons Components
• Pneumatic
• Apneustic
• Medulla
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Medulla
• Responsible for BASIC functions; has a RR of 8 to 10
• BRAIN DEAD: no function above the medulla and flat EEG but can still breathe
• COMATOSE: cerebral cortex is still alive, but patient unable to respond
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Apnea
• Central Apnea: NO inspiratory effort, with or without bradycardia, in 20 seconds or more
- • Apnea monitor
- • Tx: Caffiene; theophylline
• Obstructive Apnea: occlusion of airway during sleep, usually caused by obesity
- • Snoring will cause R sided hypertrophy and HF
- • Weight loss
- • Progesterone
- • CPAP
- • Surgery: Uvulopalatoplasty
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Pons
• RESPONDS to the environment
• Locked-In syndrome: damage to pons; patient only able to blink as response
• Most sensitive to osmotic shifts > Central Pontine Demylinolysis
• Apneustic center: senses hypoxia; causes inspiration
• Pneumotactic center: senses hypercarbia; causes exhalation (obst lung disease)
• pCO2 regulator
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Kussmaul Breathing
• RAPID, DEEP breathing
• ↑pCO2
• Means METABOLIC ACIDOSIS
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Apneustic Breathing
• Pneumotactic center is desensitized, as in COPD
• A lesion below the pneumotactic center but above the apneustic center
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Cheyne-Stokes Syndrome
• knock out the medulla
• Occurs when ↓ glucose and ↓ blood supply
• Remove ATP from medulla (when hungry)
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Thoracic Outlet Syndrome
• Born with a extra, high cervical rib
• When the child turns his head the cervical rib will impinge on the subclavian → a vacuum forms and forces blood to stop being shunted to vertebral artery
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Subclavian Steal Syndrome
• atherosclerosis of proximal subclavian
• Once they raise their arms cut off subclavian artery and pass out
• Seen in elderly
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Obstructive Lung Diseases
• Bronchitis
• Bronchiolitis
• Asthma
• Cystic fibrosis
• Bronchiectasis
• Emphysema
- • Panacinar
- • Centroacinar
- • Distoacinar
- • Bullous
• Staph aureus
• Pseudomonas
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