Usmle 1 Pulmonary Physiology

• 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

• • Decreases atmospheric pressure effect on alveoli
•   • PREVENTS ATELECTAS

• • Making surfactant if detect phosphatidylglycerol
•   • breakdown product of surfactant
•   • not completely made until 32-34 wks

• Increases compliance of alveoli

• • Compliance
•   • change in volume / change in pressure

• • Lecithin Sphingomyelin ratio is 2:1 (L/S)
•   • indicate maturity completion

• • If both are negative
•    • from  L / S ratio 2:1
•    • from phosphatidylglycerol
•      • Treat w Beclomethasone
•      • Treat w Betamethasone 

• • If baby still born early
•   • apply synthetic surfactant

• Diffusion problem

• • Collapsed alveoli 
•   • no oxygen exchange 
•   • Respiratory Distress Syndrome 
•   • Pulmonary distress in a Premature Baby

• • When a premature baby is born
•   • goes into respiratory distress
•   • until his alveoli pop open.

• • Need to give baby Oxygen to
•   • create a concentration gradient 
•   • will allow Oxygen to get into the lungs.

• • Too much O₂
•   • more free radical formation 
•   • lungs undergo metaplasia and
•   • will form a hyaline membrane

• First Restrictive lung 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

• • Need to put baby on a ventilator
•   • PEEP/CPAP
•   • JET VENTILATOR

• • JET VENTILATOR
•   • allows oxygenation and ventilation through an interrupted airway without obstructing the surgical field

• • PEEP/CPAP
•    • This provides a positive airway pressure 
•    • keeps the alveoli open 
•    • gives some RV

• • CPAP 
•   • Continuous Positive Airway Pressure

• • PEEP
•   • Positive End-Expiratory Pressure

• • Complication:
•   • bilateral pneumothorax 
•   • increased pressure required infuse the oxygen
•     • Will need chest tube.

• • The free radicals made by oxygen
•   • will irritate the airway
•   • stimulates mucous production

• • Free radicals damage Goblet cell
•   • hyperplasia 
•   • hypertrophy
•   • Narrow airway lumen 
•     • Obstructive lung disease 
•     • Bronchopulmonary dysplasia 
•       • abnormal growth

• • Kussmaul sign:
•   • increased JVD on inspiration

• • Pulsus paradoxus:
•   • exaggerated drop in BP 
•     • more than 10mm
•   • pulse rate 
•     • more than 10 bpm

• Loss of pulse and BP

• • Cyanosis
•   • lack of oxygen in the blood
•   • bluish or grayish discoloration of the skin 

• • Hamman’s sign:
•   • subcutaneous emphysema

• • Tx: 
•   • Ventilators

• 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

• • ARDS 
•   • Acute Respiratory Distress Syndrome
•   • severe inflammation in the lungs

• • Most common cause
•    • Sepsis
•       • Will need intubation and ICU
•       • Will have same disease course and complications as child
•       • 60% mortality rate

• 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 perform a back thrust
•   • For an adult → Heimliech Manuver

• Glottis

• Middle of the trachea (landmark → aortic arch)

• Bifuraction of the Trachea at T4

• • MCC of Death → Bronchiectasis
•   • bronchi are thickened from inflammation and infection

• • Restrictive Disease 
•   • problem in the interstitium

• • Obstructive Disease 
•   • caused by Bacteria producing mucus in Airway
•  

• • EVERY lung disease
•   • Presents SAME signs and symptoms !!!
•   • SOB & weakness
•     • dyspnea, and tachypnea

• Difficulty breathing OUT

• Problem with VENTILATION

• Too much airway mucus

• Airway thickening

• Goblet cell hyperplasia

• Increased Reid Index

• • Mcc of death:
•   • BRONCHIECTASIS

• • ABG:  (Arterial Blood Gas)
•   • Normal pO2 
•   • ↑ pCO2
•   • ↑ respiration 
•   • ↓ pH

• • EVERY lung disease
•   • Presents SAME signs and symptoms !!!
•   • SOB & weakness
•     • dyspnea, and tachypnea

• • Problem in the interstitium
•   • network of fluid-filled spaces 
•   • within tissues and organs

• • O2 diffusion will be affected the most
•   • diffusion and perfusion limited

• • CO2 diffuses fast so it is airway limited
•   • airway problems
•   • ventilation problems

• • ABG:  (Arterial Blood Gas)
•   • ↓ pO2 
•   • ↓ pCO2
•   • ↑ respiration 
•   • ↑ pH

• • Function:
•   • cushions the fetus from impacts
•   • regulates temperature
•   • allows for movement
•   • provides essential nutrients
•   • medium for waste removal
•   • possesses antimicrobial properties 
•   • safeguarding against infections

• • Composition
•   • 80% is filtrate of mom’s plasma
•   • Baby must be able to Swallow & digest it
•   • adds 20% to it then urinates in the amniotic sac

• • baby can’t swallow or absorb fluid 
•   • ANS
•   • Neuromuscular Disease
•      • Werdnig-Hoffman syndrome
•   • UGI atresia
•      • Esophageal atresia
•      • Duodenal atresia

• • autonomic nervous system (ANS)
•   • doesn't function properly

• Riley-Day syndrome

• Low amnionic fluid

• • Baby has renal defect 
•   • agenesis or obstruction
•   • can’t pee 
•     • can’t add 20%

• Potter’s syndrome

• Low amnionic fluid

• • low pressure effects on the fetus 
•   • everything is flattened
•   • smashed face

• • Will lead to issues due to the positive pressure
•   • pulmonary aplasia
•   • hypoplasia

• • No Abdominal wall muscles, therefore
•   • can’t bear down to pee, so there is
•   • no muscle to push fluid out
•   • creates ­pressure, prune appearance in baby

• • This baby will dies of infections (UTI)
•   • because always has a catheter

• • Positive pressure
•   • (high) P to push towards negative (lower)P

• • Negative pressure
•   • (lower) P to allow positive (higher) P to fxn

• • Extra thoracic 
•   • outside chest cavity 
•   • From the lips to the glottis
•   • NOT protected by the thoracic cage

• • intrathoracic 
•   • inside chest cavity are
•   • From the glottis to the alveoli
•   • Protected by the thoracic cage
•   • Has a vacuum surrounding it

• Intra & Extra separated by glottis

• • Breath in (inspiration)
•   • Extra thoracic collapses 
•   • intrathoracic expands

• • Breath Out (expiration)
•   • Extra thoracic expands
•   • intrathoracic narrows

 

• • Main stem Bronchus
•   • Breaks into parenchyma ½ way
•   • gets smaller

• • After Main stain bronchi will divide into
•   • large bronchioles
•   • medium bronchioles
•   • small bronchioles

• • Terminal Bronchiole
•   • Most dependent part of airway
•   • most Lung Cancers like to form here

• Will deposit in 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 cleans out the dead space

• The diaphragm forms from Ventral to Dorsal

• • Bochtalek defect
•   • rear defect

• • Morgagni defect
•   • anterior, midline defect
•   • Visible by sonography in utero
•   • Bowel sounds in chest exam
•     • Must repair surgically immediately after birth

• • Has 16 to 20 C-shaped cartilage rings
•   • opening to the C facing posteriorly
•     • This allows partial collapse of the airway during swallowing to prevent aspiration

• • Has three anatomic narrowing's
•   • The glottis
•   • Midway: due to anterior compression by aorta
•   • Carina: located at T4 (level of nipple)

• • If patient is unable to speak
•   • object is lodged in the trachea

• • LARGE OBJECTS tend to lodge at the glottis
•   • 90% of time

• Perform the Heimlich Maneuver

• Perform Back Thrusts if less than 2 y/o

• • If still unable to dislodge the object…
•   • Perform emergency cricothyroidotomy

• • Small objects tend to lodge
•   • in the right lower lobe

• • Recurrent RLL pneumonia:
•   • R/O FB aspiration
•   • Do inspiratory
•   • expiratory films

• • Right mainstem bronchus 
•   • larger and straighter than the left

• • If person is sitting or standing UP
•   • object will lodge in the superior segment

• • If patient is lying DOWN
•   • object will lodge in the posterior segment

• • Inspiratory film:
•   • all lobes are inflated

• • Expiratory film:
•   • lobe with aspirated object does NOT collapse

• • Tx:
•   • bronchoscopy

• True measure of ventilation is in 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!!!
• 

• • Normal Rate 12-16
•   • Restrictive needs more O₂ (I)
•   • Obstructive needs less  O₂ (E)

• • 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? 

• • Diaphragm normally develops
•   • Ventral (midline) to Dorsal (back)

• • Diaphragmatic hernia
•   • Intestines are in thoracic cavity
•   • Present with bowel sounds in the chest cavity
•      • See feeding tube curled in his chest on x-ray
•   • Common types:
•      • Bochdalek (90%)
•        • Herniation is in the back
•   • Morgagni (10%)
•      • Herniation is in the front/mid-line
•   • Complication
•      • The lung won’t develop bcs
•      • GI/Intestines are pushing down on the lungs and
•      • can’t inflate = pulmonary hypoplasia
•      • Next step is to try and close the hole
•         • Need at least 90% of the lung to develop in order to live.

• • Trachea 
•   • Top 1/3 
•     • Squamous cells (protect against abrasion)
•   • Middle 1/3 
•     • Transition cells
•   • Lower 1/3 
•      • short columnar epithelium
•      • Beat upward 
•        • to swallow foreign debris
•        • let stomach acid digest it

• • Tall columnar ciliated epithelium 
•   • bottom 1/3 and into bronchus

• • Cilia
•   • 9 microtubules surrounding 2 actin proteins 
•     • With a Dynein Arm for flexibility

 

• • Allow cilia to disengage from mucus
• • 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

• • 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

• Strep Pyogenes

• S pneumonia - encapsulated

• H influenza - encapsulated

• • Neisseria Catarrhalis - encapsulated
•   • These bacteria can live in the back of throat
•   • because they contain IgA Protease 
•     • protect against IgA activity
•   • MCC of:
•     • sinusitis
•     • otitis
•     • bronchitis
•     • pneumonia

• • Cilia prevents these bacteria from entering lungs
•   • if the cilia is paralyzed they can enter the lungs
•   • Viral infections can paralyze cilia 
•     • allow for the encapsulated organisms to enter

• Most numerous

• Serve to produce mucus to trap debris

• Mucus moves 1 inch per cough

• 95% of pneumocytes

• mostly macrophages  

• Found mostly in terminal bronchus    

• where all the dust will settle

• 5% of pneumocytes

• produce surfactant  

• Found in alveoli surrounding alveolar membrane

• • Can become type I. can’t go other way round    
•   • Type I can not become Type II

• macrophages that ingest dust particles  

• found in terminal bronchus

• • 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
•   •  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
•       • Medium bronchioles

• • Tracheal and Laryngeal cartilage
•   • neural crest origin (septum)

• • Trachea has 16-20 C shaped cartilage rings
•   • Why C-Shape:
•     • Opening faces backwards for 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 not fully encircled it would collapse

• • Stops at the Respiratory unit
•   • allow for diffusion
•   • Terminal Bronchiole 
•     • end of cartilage
•       • has to be only one layer of cells

• windpipe above your trachea 

• • make sounds
•   • called your voice box

• • Stridor:
•   • narrowing in extrathoracic airway
•   
• • Wheeze:
•   • narrowing in intrathoracic airway

• • Rhonchi:
•   • air moving over mucus

• • Crackles:
•   • collapsed airways “popping” open
•     • due to Surfactant gone
•     • due to Scarred down (fibrosis)

• • Decreased breath sounds:
•   • space between alveolus and chest wall occupied

• • Dullness to percussion: as above
•   • space between alveolus and chest wall occupied

• • Increased fremitus:
•   • due to consolidation on same side 
•   • due to atelectasis on opposite side

• Bronchophony

• Egophony

• • Tracheal deviation:
•   • towards atelectasis
•   • away from pneumothorax

• • Hyper resonance:
•   • due to pneumothorax on same side 
•   • due to atelectasis on opposite side

• above the glottis

• • narrowing in extra thoracic airway
•   • Inspiratory sound only
•   • Problem is from Lip to the glottis
•     • need a lateral neck film
•     • Macroglossia (big tongue) seen in:
•       • storage disease 
•       • hypothyroidism 
•       • Down’s

• • 2nd Brachial Arch problem 
•   • micrognathia (small jaw)
•     • Pierre-Robin
•     • Treacher Collins

• • heard through stethoscope during lung auscultation 
•   • an abnormal increase in the clarity 
•   • loudness of the patient's spoken voice

• change in the sound of the voice heard through a stethoscope during auscultation of the lungs,

• when a patient says "E" and it is heard as "A"

• Croup

• Bronchiolitis

• Bronchitis

• Pneumonia

• tracheitis

• 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

• 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:
•   • Parainfluenza
•   • RSV (send to ER immediately)
•   • Adenovirus
•   • Influenza

• • URI 
•   • Upper Respiratory Infection

• • Acute 
•   • ↑ sputum production

• • Chronic =
•   • ↑ mucous production 
•   • at least 3 consecutive months 
•   • 2 consecutive years

• • MCC:
•   • Streptococcus pneumoniae
•   • H. influenza
•   • Catarrhalis

• Epiglotitis: H. Influenza B

• Tracheitis: C. Diptheria

• Pneumonia

• closure of trachea

• • Presentation
•   • Child will be drooling
•   • stridor
•   • muffled voice 
•   • fever

• • MCC 
•   • H. influenza B

• • Treatment
•   • Must make an airway 
•   • Intubate in the ER
•     • Look for thumb sign on CXR

• • MCC 
•   • Diphtheria 
•     • EF-2 ribosylation 
•     • gray pseudo membrane

• Stridor since birth

• Inflammation in the alveolus

• • MCC
•   • Strep pneumonia: Rusty colored sputum
•   • H flu: Staph Aureus
•   • Neisseria
•   • Klebsiella 
•   • Common after flu 
•   • Actinomycin 
•   • S aureus and pseudomonas 
•   • Anaerobic infection

• • currant jelly sputum
•  
• • homeless alcoholic
•  
• • likes fissures of lung

• S. aureus

• sulfur granules

• • bullae production
•    • due to elastase activity
•      • pneumatocele

• • foul smelling
•     
• • (+) air/fluid levels
•     
• • gas formation

• Atypicals

• Fungus

• Pneumoconioses

• Nocardia

• Sarcoidosis

• Chlamydia: from 0 to 2 mo

• Mycoplasma: from 10 to 30 y/o

• Legionella: over 40 y/o

• Histoplasmosis: midwest

• Blastomycosis: northeast

• Coccidiomycosis: southwest

• Paracoccidiomycosis: South America

• Aspergillus: moldy hay or moldy basement

• Sporothrix: rose thorn

• Asbestosis

• Silicosis

• Bissinosis

• berrylliosis

the only G+ that is partially acid fast

• noncaseating granulomas; large hilar adenopathy; high ACE levels

• • 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 
•   • really is a restrictive disease

• • 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

• • MC lung mass in children
•   • Hamartoma

• • MC lung mass in adults is:
•   • Granuloma

• • MC Tumor:
•   • adenoma

• • Bronchogenic adenocarcinoma
•   • in the glandular cells

• Bronchioalveolar adenocarcinoma

• • Carcinoid syndrome
•   • flushing
•   • wheezing
•   • diarrhea
•   • Too much serotonin
•   • Measure 5-HIAA in the urine

• Large cell adenocarcinoma

• • Primary smoking
•   • Risk increases with amount AND duration
•   • If you STOP smoking:
•    • 5 yrs > reversal of damage visible
•    • 15 yrs > risk back to baseline

• Radon

• • Second hand smoke
•   • side stream smoke 
•   • mainstream smoke

• Pneumoconiosis

• • Intrathoracic space
•  • Chest wall
•  • Pleural space

• Pulmonary vasculature

• Pulmonary airway

• • RV:
• • ERV:
• • FRC: 
• • TV:
• • IRV:
• • TLC:
• • VC:
• • Obstructive Disease
• • Restrictive Disease

• Residual volume 

• amount air left in lungs AFTER forced expiration 

• Can not be physiologically forced out 

• Maintains some compliance in the airway 

• Keeps alveoli from collapsing

• 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

• Functional residual capacity 

• FRC = RV + ERV

• Tidal volume 

• • the amount of air you take IN  
•    • during a NORMAL inhalation effort 

• 10 – 15 cc/kg

• inspiratory reserve volume 

• • the amount of air you can FORCE INSPIRE  
•  • after a normal inhalation effort

• Total lung cap 

• ALL the air in lungs at the END of a deep breath 

• RV + ERV +TV + IRV

• Volume cap 

• All the air breathe in AFTER forced exhalation 

• ERV + TV + IRV

• RV changes 1st  ↓ 

• In both TV changes last

• VC drops 1st 

• TLC drops second 

• In both TV changes last

• • 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

• • 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

• 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

• 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

• Kussmaul sign: increased JVD with inspiration

• • Pulsus paradoxicus: on inspiration
•   • exaggerated drop in BP
•    • more than 10mmHg 
•   • pulse 
•    • more than 10bpm 

• • Mcc:
•   • pericardial tamponade 
•   • pneumothorax

• is when fluid in the pericardium builds up

• if equal pressure on both sides of chest

• If recurrent: put in a pericardial window

• Mcc: trauma or cancer

• CXR: enlarged cardiac shadow

• ECHO: compressed small heart

• Tx: pericardiocentesis

• if NOT equal pressure on both sides of chest

• • Traumatic
•  • injury to the chest wall 

• • Spontaneous
•  • often in tall, thin individuals 
•  • those with underlying lung conditions
•  • Associated with estrogen use or collagen disease
•  • Less than 25% occupation & asymptomatic
•  • More than 25% occupation or symptomatic

• Tx: chest tube placement

• • 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

• (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.

• 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

• 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!

• 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

• • 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

• The Only Pressure That Gets Positive With Each Breath

• P_a = P_atm   at IRV and FRC

• P_a < P_atm   at inspiration

• P_a = P_atm   at end of deep breath

• P_a > P_atm   at expiration

• ability to distend and increase volume

• Black = normal

• Red = obstructive leaving air inside

• Blue = emphysema, trouble breathing in and breathing out. (obstruction)

• • Carotid Body
•   • located at the bifurcation of the
•     • internal carotids
•     • 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

• • J-receptors:
•   • found in the interstitium of lungs
•     • Senses interstitial particles
•     • Increases respiratory rate (Tachypnea)

• • Slow adapting receptors:
•   • found in
•     • ribs, especially the sternocostal junctions
•   • Senses stretch and inflation of ribs
•   • Causes exhalation

• Maxillary

• Ethmoid

• Sphenoidal

• Frontal

• More sensitive to elevated pCO-2

• Hypoxia and Hypercarbia (abnormally elevated CO₂) 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 )

• Pneumatic

• Apneustic

• 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

• 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

• 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

• RAPID, DEEP breathing

• ↑pCO₂

• Means METABOLIC ACIDOSIS

• Pneumotactic center is desensitized, as in COPD

• A lesion below the pneumotactic center but above the apneustic center

• knock out the medulla

• Occurs when ↓ glucose and ↓ blood supply

• Remove ATP from medulla (when hungry)

• 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

• atherosclerosis of proximal subclavian

• Once they raise their arms cut off subclavian artery and pass out

• Seen in elderly

• Bronchitis

• • Acute
• • chronic

• Bronchiolitis

• Asthma

• • Intrinsic
• • extrinsic

• Cystic fibrosis

• Bronchiectasis

• Emphysema

• • Panacinar
• • Centroacinar
• • Distoacinar
• • Bullous

• Staph aureus

• Pseudomonas