Respiratory Lecture 1 Flashcards
ventilation, diffusion, perfusion, Oxy Hgb dissociation curve, V/Q mismatch, pathophysiology
Where does Canada stand as far as resp compromise in comparison to other developed countries
considered mid-range
- 2.5 - 3 million have asthma
- 750 000 - 1 million have COPD
What is anatomical dead space
-total vol of the conducting airways from the nose to terminal bronchioles that fills with air that is exhaled again before gas exchange can occur. ~ 150 ml
What is minute volume respiration
vol of gas inhaled or exhaled from lungs in a minute
What is tidal volume
normal vol of air displaced during normal inhalation and exhalation
What is residual volume
vol of air still in lungs after most forceful expiration possible
-aka residual air
What is inspiratory reserve volume
max amount of additional air that can be inspired after normal inspiration
What is expiratory reserve volume
max amount of air that can be forcefully expired after normal expiration
What is total lung capacity
amount of gas in lungs after maximum inhalation
What is vital capacity
max vol of air that can be expelled from lungs after taking the deepest inspiration possible
What is functional residual capacity
Vol of air in lungs after normal expiration
-ERV + RV
What is inspiratory capacity
vol of gas that can be taken in on a full inhalation
-TV + IRV
What is forced expiratory volume
measures how much air can be exhaled during a forced breath
What are intrinsic factors
Factors that are within or influence by PT system.
-out of PT control
Examples of intrinsic factors
- genetic predisposition
- COPD, asthma, lung CA
- cardiac or circulatory conditions
- stress
What are extrinsic factors
Factors that are external to PT
-environmental
-Lifestyle
-
Examples of extrinsic factors
- smoking (cigarettes, vape, pot)
- enviro pollutants and toxins
What is the physiological process of repiratory system
- it is to exchange gases with the environment
- O2 diffuses into blood for use in cell metabolism
- CO2 (waste product) eliminated from body
What is the process that allows gas exchange to occur
- ventilation
- Diffusion
- Perfusion
What is ventilation
Mechanical process of moving air in and out of the lungs
What are the 2 phases of ventilation
- Inspiration
- Expiration
What 4 body structures must be intact for ventilation to occur
- chest wall
- nerve pathways & brainstem
- Diaphragm
- Pleural cavity
What is Diffusion
Movement of molecules through a membrane from an area of high concentration to an area of low concentration
gases move btw what two structures in diffusion
alveoli and pulmonary capillaries
What is the PO2 in alveoli
104mmHG
What is PO2 in pulmonary capillaries before gas exchange
40mmHg
What is movement of O2 in lungs
Moves from high concentration in alveoli to low concentration in RBC’s moving through capillaries
What is PCO2 in pulmonary capillaries
45mmHg
What is PCO2 in alveoli
40mmHg
What would increase the amount of O2 moved from alveoli into blood
a greater difference in concentration (increase concentration gradient)
What structures must be intact for adequate diffuion to occur
- alveoli (no damage/collapse)
- Resp membrane (thickness .5 - 1 micrometer)
- Interstitial space (no increase as you see w/ pulmonary edema or pneumonia)
- endothelial lining of capillaries
- no fluid accumulation of inflammation
What is perfusion
the circulation of blood through the capillaries
What are 4 conditions perfusion is dependant on
- adequate blood vol
- intact pulmonary capillaries
- efficient pumping of blood by heart
- concentration of Hb
What are the 2 ways O2 in transported
- 98% by Hb
- 2% dissolved in plasma (PO2)
What is Hemoglobin (Hb)
the transport protein that carries O2 in blood
What is structure of Hb
- 4 Heme molecules containing iron - where O2 binds and is transported
- 1 globin portion containing protein
How does O2 binding change the overall structure of Hb
- causes it to more readily bing to other O2 molecules
- forms oxyhemoglobin (HbO2)
What happens once Hb begins to release O2
it will more rapidly shed additional O2 as well
What happens when PO2 is >70 mmHg
saturation is essentially 100% and additional O2 will not make a significant difference
Why is Oxygen dissociation curve helpful
for understanding how the body carries and release O2
What does oxygen dissociation curve tell you
- relates O2 saturation (SO2) & PO2 in blood
- shows how eagerly Hb binds and releases O2 molecules into surrounding fluid
When does oxygen bind easily to Hb
in area of high O2 pressure like lungs
When does Hb release O2 more readily
-in area of low O2 pressure like the tissues
What happens when Hb releases O2
CO2 starts binding to it
When do you get and upward left shift on O2 dissociation curve
when increased affinity for O2
When do you get downward right shift on O2 dissociation curve
when you have decreased affinity for O2
What causes changes in O2 dissociation curve
- body temp
- blood PH
- PCO2
What are the 3 ways CO2 is transported from cells to lungs
- mostly as bicarbonate ions
- bound to globin part of Hb molecule
- dissolved in plasma PCO2
How is CO2 transported as bicarbonate ion
CO2 released into capillaries
- enters RBCs
- the enzyme carbonic anhydrase causes CO2 + H2O to become 2 hydrogen ions and bicarbonate (HCO3)
- the HCO3 can now leave RBC to enter plasma and be transported to lungs and be release as CO2 in gas exchange
What would cause the O2 dissociation curve to shift up and left
- increase in PH
- decrease in PCO2
- decrease in temp
What would cause the O2 dissociation curve to shift up and right
- decrease in PH
- increase in PCO2
- increase in temp
What structures must be intact for adequate perfusion
- pulmonary capillaries must be open/ not occluded (so no pulmonary emboli)
- heart must pump efficiently through pulmonary capillaries (ex. acute pulmonary edema)
What is respiration
the exchange of gases btw a living organism and its environment
-pulmonary respiration
Where does pulmonary respiration occur
- in the lungs
- gases exchanged btw alveoli and the RBCs in pulmonary capillaries through membranes
What is cellular respiration and where does it occur
- exchange of gases btw RBCs & various tissues
- occurs in peripheral capillaries
What does the V and Q stand for in V/Q mismatch
V= ventilation Q= Perfusion
When does V/Q mismatch occur
- when anything increases / decreases ventilation of the lungs or perfusion of the lungs
- Anything that interferes with ability of fresh air to get to alveoli or prevents blood flow to the capillaries
What are the 7 possible causes of V/Q mismatch
- Decreased ambient O2 supply
- Mechanical Ventilations
- Perfusion mismatch
- Decreased surface area
- Cardiac output
- Hb issues
- Histotoxin
What is decreased ambient O2 supply
Inadequate O2 available in atmospheric air
- CO poisoning
- Altitude
- Confined space
- Drowning
- Noxious exposure
What are mechanical ventilations
Breathing mechanics are interrupted which interferes with process of bringing in the air
- foreign body airway obstr.
- CNS disruption
- chest wall injury
- lung injury
- neuromuscular diseases interfering w/ muscle action (MS, MD)
What is perfusion mismatch
Blood isnt getting to alveolar surface to pick up O2
- Hypovolemic shock
- Pulmonary embolism
- dehydration
What is decreased surface area
Total area O2 can come across has been reduced
- decrease in surfactant (=atelectasis)
- emphysema
- lung CA
- aspiration
What is cardiac output (re: V/Q mismatch)
Heart is not pumping out the blood to get it to the lungs, cant get to destination for gas exchange
- AMI
- Overdose
- shock
- valve failure
- pericarditis
- cardiac tamponade
- dysrhythmia
- cardiac arrest
What are the Hb issues re: v/q mismatch
Hb not functioning properly or malformed or absent
- sickle cell anemia
- anemia
- hemorrhage
- iron deficiency
- CO poisoning
What is histotoxin
the actual cells cannot use the O2 that is delivered to them because of cellular damage
- cyanide poisoning
- Smoke inhalation of household fires during the burning of rubber and plastic predominantly
- Cyanide inhibits mitochondrial cytochrome oxidase
- Blocks electron transport, resulting in decreased oxidative metabolism and oxygen utilization.
Respiratory disease limits the body’s ability to do what
get rid of waste products
-results in disruption of ventilation, diffusion, perfusion
What 3 areas can cause disruption in ventilation
- upper/lower respiratory tract
- Chest wall & Diaphragm
- Nervous sytem
What can cause obstructed air flow in upper/ lower resp tract
- trauma (bleeding, swelling)
- infections (epiglottitis, tonsillitis, abscess)
- foreign body aspiration
- mucous accumulation (asthma)
- smooth muscle constriction (COPD, asthma)
- airway edema (inf, burns)
What affect does upper resp tract obstruction have on respiratory system
- diseases that affect upper tract will obstruct air flow to lower structures
What are mechanical components essential for normal ventilation
chest wall & diaphragm
How do traumatic injuries disrupt mechanics of chest wall and diaphragm
Cause loss of neg pressure within pleural space = limited ability to expand thoracic cavity
- pneumothorax
- flail chest
- diaphragmatic rupture
How do infectious processes & inflammatory conditions disrupt mechanics of chest wall and diaphragm
simillar symptoms as traumatic - loss of pressur in pleural space reducing thoracic cavity ability to expand
-emphysema
How do neuromuscular diseases disrupt mechanics of chest wall and diaphragm
they impair muscle function
How can nervous system disrupt ventilation
any disease process that impairs nervous system’s regulation of breathing can alter ventilation
What issues in nervous system can cause disruption to ventilation (examples)
- CNS depressant (alcohol, benzodiazepines, barbiturates)
- stroke, disease, injury to resp center in CNS
- damage to major PNS that supply diaphragm (phrenic) & intercostal muscles (intercostal nerve): chest sx, penetrating trauma
Describe Cheyne-strokes respirations
tidal volume progressively get deeper and more rapid then is followed by decline in volume and periods of complete apnea at end of expiration
- about 30 to 2 mins of dysrhythmic respirations followed by a period of apnea
What are causes of cheyne-strokes respirations
- older Pts with terminal illness
- Brain injuries
Describe Kussmaul’s respirations
Deep, laboured, rapid breathing
-corrective measure against metabolic acedosis
What are causes of Kaussmaul’s respirations
- diabetic ketoacidosis (most common)
- renal failure
Describe central neurogenic hyperventilation
- deep & rapid breaths at a rate of at least 25 bpm
- respiratory alkalosis often present
- increasing irregularity of this respiratory rate generally is a sign the Pt will enter coma
What causes central neurogenic hyperventilation
- stroke
- injury to the brainstem
Describe ataxic (Biot’s) respirations
- repeated episodes of gasping ventilations, separated by periods of apnea
- irregularly irregular breathing
What causes Ataxic (Biot’s) respirations
- damage to the medulla oblongata (stroke)
- increased intracranial pressure
Describe apneustic respirations
- deep, gasping inspirations w/ a pause at full inspiration followed by a brief insufficient release
- seperated by periods of apnea
what causes apneustic respirations
- stroke
- CNS diseases
What is hypoxia
a state in which insufficient O2 is available to meet the O2 requirements of the cell
What causes hypoxia
- any changes to concentration of O2 in alveoli (high altitude)
- disease that affect # of usable alveoli (environmental pathogens, COPD, inhalation injury)
How does alteration of thickness of respiratory membrane disrupt diffusion
Accumulation of fluid and inflammatory cells in the interstitial space create high pressure in pulmonary cap’s which pushes fluid out of the circulatory system
What are the 2 cardiogenic causes that disrupt diffusion
- L sided heart failure (increased venous pressure from poor L ventricle function)
- Pulmonary hypertension (high resting pressure in pulmonary circulation causing R sided heart fail)
How do non-cardiogenic genic causes disrupt diffusion
changes in permeability (leakiness) of pulmonary capillaries
What are some non-cardiogenic causes for disruption in diffusion
- adult respiratory distress syndrome
- asbestos
- environmental pathogens
- near drowning
- prolonged hypoxia
- inhalation injury
What conditions alter capillary endothelial lining (disrupting diffusion)
atherosclerosis
Alterations in normal blood flow through pulmonary capillaries limits what?
normal gas exchange in lungs (disrupting perfusion)
Problems reducing circulatory volume disrupt what process
perfusion
What are some problems that cause a reduction in circulatory volume
= Hypovolemia
- trauma
- hemorrhage
- dehydration
- shock
What would a reduction in normal circulating Hb disrupt
Perfusion
What could cause anemia
- acute blood loss
- iron or vitamin deficiency
- malnutrition
- chronic disease
What is pulmonary shunting
when an area of the lung is appropriately ventilated but no cap diffusion
-the available O2 is not moved into circulatory system
What is a pulmonary embolism
-blood clot that develops in the body (often legs) and then travels to lung artery where it suddenly blocks blood flow
How does pulmonary embolism disrupt perfusion
- the blockage prevents perfusion of the lung segment supplied by that branch of the artery
- there may be a significant shunt of unoxygenated blood to the pulmonary venous circulation
