Respiratory Apex Review Flashcards
What does oxygen content (CaO2) tell you?
How much oxygen is present in 1 deciliter (100 mL) of blood
What is the formula for CaO2?
CaO2 = (1.34 x Hgb x SaO2) + (PaO2 x 0.003)
What does DO2 tell you?
How much O2 is delivered to the tissues per minute
What is the formula for DO2?
DO2 = CaO2 x CO x 10
___ is needed for oxygen delivery but not oxygen-carrying capacity.
CO
What is the reference value for CaO2?
20 mL O2 /dL
What is the reference value for DO2?
1,000 mL O2 per minute
What is the definition of oxygen consumption?
The difference between the amount of O2 that leaves the lungs and the amount of O2 that returns to the lungs
What is the formula for VO2?
VO2 = CO x (CaO2 -CvO2) x 10
What is the reference value for VO2?
250 mL/min or 3.5 mL/kg/min
What is 1 deciliter equal to?
100 mL
What two ways is oxygen transported by the blood?
- reversibly w/ Hgb (97%)
- Dissolves in the plasma (3%)
What percentage of oxygen reversibly binds with Hgb?
97%
What percentage of oxygen is dissolved in the plasma?
3%
Each gram of Hgb molecule can carry a theoretical max of ___ mL of molecular oxygen.
1.39
What is the normal Hgb for a male?
15 g/dL
What is the normal Hgb for a female?
13 g/dL
What is the normal Hct for a male?
45%
What is the normal Hct for a female?
39%
How is dissolved O2 measured?
By PaO2
What does PaO2 determine?
Gas exchange in the lungs (not a measure of oxygen content in the blood)
Oxygen dissolves in the plasma according to ____ law.
Henry’s
What is the solubility coefficient for oxygen?
0.003 mL/dL/mmHg
Oxygen is _____x less soluble than CO2.
20
What is the driving mechanism of DO2?
CO
VO2 stands for ______
oxygen consumption
What principle can be used to calculate oxygen consumption?
Fick’s principle
What does the oxyhemoglobin dissociation curve tell us?
the tendency of Hgb to bind to oxygen
A right-shifted curve of the oxyhemoglobin dissociation curve means Hgb has a ____ affinity for oxygen.
lower (right = release)
A left-shifted curve of the oxyhemoglobin dissociation curve means Hgb has a ____ affinity for oxygen.
higher (left = love or locked in)
What is the P50?
When Hgb is 50% saturated by oxygen
A low P50 indicates a ____ shifts of the oxyhemoglobin dissociation curve.
left
A high P50 indicates a ____ shifts of the oxyhemoglobin dissociation curve.
right
A left shift of the oxyhemoglobin dissociation curve is caused by _____, ______ temperature, and _______ 2,3-DPG.
alkalosis, decreased temperature, and decreased 2,3-DPG
A right shift of the oxyhemoglobin dissociation curve is caused by _____, ______ temperature, and _______ 2,3-DPG.
acidosis, increased temperature, increased 2,3-DPG
What three hemoglobin species can cause a left shift of the oxyhemoglobin dissociation curve?
- fetal hemoglobin
- methemoglobin
- carboxyhemoglobin
Above a PaO2 of _____ mmHg, hemoglobin is fully saturated with oxygen.
100
What does the Bohr effect say?
An increased partial pressure of CO2 and decreased pH cause Hemoglobin to release O2
Max O2 loading occurs at a PaO2 of what?
100 mmHg
Tissues with a high metabolic rate consume more ___ and produce more _____, ______, and ______.
O2; CO2, hydrogen ions, and heat
When is 2,3-DPG produced?
during RBC glycolysis (Rapoport-Luebering pathway)
What increases 2,3-DPG production?
Hypoxia
2,3 DPG is an important compensation mechanism during chronic ____.
anemia
In _____, the concentration of 2,3-DPG falls.
banked blood
What does not respond to 2,3-DPG?
Hgb F
What is the energy currency in the body?
Adenosine triphosphate (ATP)
What is the primary substrate used for ATP synthesis?
Glucose
What 3 key processes are involved in aerobic metabolism?
- glycolysis
- krebs cycle
- oxidative phosphorylation
How many ATP are gained with glycolysis?
net gain of 2 ATP
How many ATP are gained with Krebs cycle?
Net gain of 2 ATP
How may ATP are gained with oxidative phosphorylation?
net gain of 34 ATP
Anaerobic metabolism occurs when?
in the absence of oxygen
In the absence of oxygen, ______ is converted to lactic acid.
Pyruvate acid
Why does lactic acidosis occur during the absence of oxygen?
B/c pyruvate acid is converted to lactic acid during anaerobic metabolism
How is ATP produced?
by the oxidation of proteins, carbohydrates, and fats
The phosphate bond in ATP is a _____ energy bond.
high
Why must ATP be continuously replenished?
It cannot be stored
Which form of metabolism produces much more ATP?
aerobic
What is the primary goal of glycolysis?
to convert 1 glucose to 2 pyruvic acid molecules
The fate of pyruvic acid depends on whether or not _____ is available.
oxygen
In the absence of O2, pyruvic acid is converted to lactate where?
in the cytoplasm
If oxygen is present, where is pyruvic acid transported after glycolysis?
the mitochondria
During glycolysis of aerobic metabolism, the 2 molecules of pyruvic acid are converted into what?
2 molecules of acetyl coenzyme A
When is 2,3-DPG produced?
about halfway through glycolysis
During what pathway is 2,3-DPG produced?
the rapoport-luebering pathway
Where does the Krebs cycle take place?
in the matrix of the mitochondria
The krebs cycle is also known as what?
citric acid cycle
During the krebs cycle, the reaction begins when _____ and ______ react to produce citric acid.
acetyl coenzyme A
and
oxaloacetic acid
The Krebs Cycle reaction ends with the production of ____, ____, and _____.
oxaloacetic acid, NADH, and CO2
What is the primary goal of the krebs cycle reaction?
to produce a large quantity of H+ ions in the form of NADH
What is the primary goal of glycolysis and the Krebs cycle?
to liberate hydrogen from glucose
The NADH produced during the Krebs cycle is split into what?
NAD+, H+, and 2 electrons
During oxidative phosphorylation, the electrons produced from NADH are fed into the chemiosmotic mechanism. And a proton gradient is generated across a membrane which drives ________ with the help of ______.
ATP synthesis; ATP synthase
What serves at the final electron acceptor during oxidative phosphorylation?
oxygen
What are the 2 end products of oxidative phosphorylation?
- 34 ATP molecules
- water
What is the end product of anaerobic metabolism?
lactic acid
How much ATP molecules are created from pyruvic acid during the lactic acid pathway?
2 ATP
What type of acidosis is lactic acidosis?
anion gap metabolic acidosis
Why is there altered homeostasis in the setting of acidosis?
the body’s enzymes tend to not function properly in an acidic environment
How is serum lactate cleared?
the liver
What is the primary by-product of aerobic metabolism?
Carbon dioxide
What are the 3 primary ways that CO2 is transported/buffered in the blood?
- as bicarbonate
- bound to Hgb
- dissolved in the plasma
What % of CO2 is transported/buffered as bicarbonate?
70%
What % of CO2 is transported/buffered bound to Hgb?
23%
What % of CO2 is transported/buffered dissolved in the plasma?
7%
What is the enzyme that facilitates the formation of carbonic acid (H2CO3) from H2O and CO2?
Carbonic anhydrase
To maintain electroneutrality, for every molecule of HCO3- that leaves the erythrocyte, 1 _____ ion is transported in.
Cl-
What is the Hamburger shift?
To maintain electroneutraility, for every molecule of HCO3- that leaves the erythrocyte, 1Cl- ion is transported in.
Why is venous blood slightly more acidic?
The PvCO2 (venous blood) is about 5 mmHg higher than the PaCO2 (arterial blood).
What is the normal venous pH?
7.36 (as opposed to normal arterial pH = 7.4)
Metabolically active tissues create a more _____ environment.
acidic
A more acidic environment, enhances _____ from hemoglobin (Bohr effect) and _____ loading on hemoglobin (Haldene effect).
O2 offloading; CO2 loading
What is the Haldene effect?
CO2 loading onto Hgb in acidic environment
What is the Bohr effect?
O2 offloading in acidic environment
How is CO2 eliminated from the pulmonary blood?
alveolar ventilation
What is the Bicarbonate - Carbonic Acid Buffer Reaction?
H2O + CO2 <—> H2CO3 <—> H+ + HCO3-
What is required for the bicarbonate - carbonic acid buffer reaction to take place?
carbonic anhydrase
Where is carbonic anhydrase present? And where is it not?
Present in the erythrocyte
NOT present in the plasma
Why does the formation of carbonic acid reaction have to be fast?
RBCs only remain in capillary blood for a short period of time
What facilitates the formation of carbonic acid (H2CO3)?
Carbonic anhydrase
What is H2CO3?
Carbonic acid
Carbonic acid rapidly dissociates into ____ and _____.
H+ and HCO3-
What happens to the dissociates of carbonic acid?
the H+ is buffered by Hgb
the HCO3- is transported to plasm to act as a buffer
Where does the chloride shift (Hamburger shift) happen in reverse?
in the lungs as CO2 is excreted from the body
Venous Hct is _____ than arterial Hct.
@3% higher
Why is venous Hct higher than arterial Hct?
The chloride shift adds osmotically active ions (Cl-) to the erythrocyte in venous circulation. Water follows isosmotically, causing the erythrocyte to swell. The cell volume is increased relative to the plasm volume.
What is the carbamino compound buffer?
CO2 binds with amino groups on Hgb as well as other plasma proteins
What is the solubility coefficient of dissolved CO2?
0.067 mL/dL/mmHg
CO2 is 20x more soluble in the blood than what?
O2
The Haldene effect states that in the presence of deoxygenated Hgb, the CO2 dissociation curve shifts ____.
to the left
What does the Haldane effect describe?
CO2 carriage
The Haldane effect states that oxygen causes the erythrocyte to release ____.
CO2
The presence of oxygenated Hgb shifts the CO2 dissociation curve to the ____.
Right
The presence of deoxygenated Hgb shifts the CO2 dissociation curve to the ____.
left
What does the Bohr effect describe?
O2 carriage
The Bohr effect says what?
That CO2 and decreased pH cause the erythrocyte to release oxygen.
Why does oxygenated Hgb shift the CO2 dissociation curve to the right?
Blood can hold less CO2
Why does deoxygenated Hgb shift the CO2 dissociation curve to the left?
Blood can hold more CO2
Where in the body is the CO2 dissociation curve right shifted?
the lungs
Why is the CO2 dissociation curve right-shifted in the lungs?
This facilitates CO2 elimination
Where in the body is the CO2 dissociation curve left-shifted?
The systemic capillaries
Why is the CO2 dissociation curve left-shifted in the systemic capillaries?
This facilitates CO2 loading and transport by Hgb
Hypercapnia is defined as a PaCO2 > than ____mmHg.
45
What are the 3 etiologies of hypercapnia?
- increased CO2 production
- decreased CO2 elimination
- rebreathing
Sepsis, MH, thyroid storm, burns, and shivering are all causes of _____ CO2 production.
increased
Airway obstruction, ARDS, COPD, and opioid OD are all causes of ______ CO2 _____.
decreased CO2 elimination
What are some causes of rebreathing?
exhausted soda lime, faulty unidirectional valve in a circle system, or inadequate FGF in a Mapleson circuit
What are some consequences of hypercarbia?
hypoxemia, acidosis, cardiac depression, SNS stimulation, increased ICP
What is the formula for PaCO2?
PaCO2 = CO2 production / alveolar ventilation
With hypercapnia, the oxyhemoglobin curve shifts ____.
right
CO2 is a ______ depressant.
myocardial
CO2 directly ____ the peripheral vasculature
dilates
CO2 activates the ____ and increases ____ release from the adrenal medulla
SNS; catecholamine
With mild acidosis, the SNS stimulation r/t hypercapnia offsets what other s/e?
cardiac depression and direct peripheral vasodilation
CO2 is a smooth muscle dilator with the exception of what?
pulmonary vasculature
CO2 has what affect of PVR?
Hypercapnia increases PVR
An increased PVR increases the workload of the ____
right heart
Hypercapnia activates the ____ pump
H+/K+ …. Buffers CO2 acid in exchange for releasing K+ into plasma
What electrolyte effects does hypercapnia cause?
Increased K+ and increased Ca+
With acidosis, plasma proteins buffer H+ and release _____.
Ca+
Can CO2 freely diffuse across the BBB?
yes
Hypercapnia _____ ICP
increases
CO2 narcosis occurs when the PaCO2 is greater than what?
90 mmHg
During respiratory acidosis, the kidneys do what?
excrete H+ and conserve bicarbonate to return pH to normal
With acute respiratory acidosis, for every PaCO2 10 mmHg increase above 40 mmHg, pH decreases by ____.
0.08
With chronic respiratory acidosis, for every PaCO2 10 mmHg increase above 40 mmHg, pH decreases by ____.
0.03
Why is the decrease in pH less for chronic respiratory acidosis versus acute respiratory acidosis?
With chronic respiratory acidosis, there is HCO3- retention built up by the kidney
The carbon dioxide ventilatory response curve describes the relationship between ____ and ______.
PaCO2 and minute ventilation
What is the primary monitor of PaCO2?
the central chemoreceptor in the medulla
What are secondary monitors for PaCO2?
the peripheral chemoreceptors in the carotid bodies and transverse aortic arch
Where are the peripheral chemoreceptors that monitor PaCO2 located?
carotid bodies and transverse aortic arch
What conditions shift the CO2 response curve down and to the right?
- volatiles
- opioids
- NMBD
- metabolic alkalosis
- CEA
What conditions shift the CO2 response curve to the left?
- hypoxemia
- metabolic acidosis
- surgical stimulation
- intracranial HTN
What is the apneic threshold?
the highest PaCO2 at which a person will not breathe (once exceeded, the patient will begin to breathe)
Minute ventilation increases w/ PaCO2 in a linear fashion when PaCO2 is between ____ - ____ mmHg.
20-80
CO2 is a respiratory depressant when PaCO2 exceeds ____ - _____ mmHg.
80-100 mmHg
MAC of CO2 = _____ mmHg
200
What does the slope of the carbon dioxide ventilatory response curve represent?
The sensitivity of the entire respiratory apparatus to PaCO2
A left shift and increased slope of the carbon dioxide ventilatory response curve indicates what?
That Ve is higher than expected for a given PaCO2. This creates respiratory alkalosis
A right shift and decreased slope of the carbon dioxide ventilatory response curve indicates what?
That Ve is lower than expected for a give PaCO2. This creates respiratory acidosis.
What is the pacemaker for normal breathing?
Dorsal respiratory center
Where is the respiratory center located?
In the reticular activating system in the medulla and pons
The respiratory center receive afferent input from the central and peripheral chemoreceptors as well as _____.
Stretch receptors in the lungs
What two respiratory groups are a part of the medullary respiratory centers?
dorsal respiratory group and ventral respiratroy group
When is the dorsal respiratory group active?
During inspiration
When is the ventral respiratory group active?
During expiration
What two centers are part of the pontine respiratory centers?
pneumotaxic center and apneustic center
Where is the pneumotaxic center located?
upper pons
Where is the apneustic center located?
lower pons
What center inhibits the DRG?
pneumotaxic center (upper pons/of pontine)
What center stimulates DRG?
apneustic center (lower pons/pontine)
The respiratory rate & pattern are determined by what?
Medulla, Carotid bodies & Aortic arch & Lung baroreceptors
Where is the neural control of respiration located?
Respiratory center of medulla
The locations for chemical control of respiratory rate & pattern are determined by?
central chemoreceptors - medulla
peripheral chemoreceptors - carotid bodies and aortic arch
Where do the efferent pathways of the respiratory system terminate?
diaphragm, intercostals, and accessory muscles
What can modify the efferent response of the respiratory center?
The cerebral cortex
What is located in the medulla?
Dorsal respiratory group and ventral respiratory group
When is the DRG (dorsal respiratory group active)?
primarily active during inspiraiton
The respiratory pacemaker function is performed by the central pattern generator, which includes the ____, ______ (in the VRG), and other medullary strucutres.
DRG, pre-Botzinger complex (per Apex, if you see a question on this on the exam, first pick pre-botzinger complex if it is an option, if not pick DRG)
When is the ventral respiratory group active?
primarily active during expiration
When does the ventral respiratory group become more important?
during exercise or stress
What is located in the pons?
pneumotaxic center and apneustic center
What does the pneumotaxic center do?
inhibits the DRG (inhibits the pacemaker)
What does the apneustic center do?
stimulates the DRG (stimulates the pacemaker)
Is the pneumotaxic center located in the upper or lower pons?
Upper
What is the function of the pneumotaxic center?
To trigger the end of inspiration by inhibiting DRG
A strong stimulus of the pneumotaxic center promotes what kind of breathing?
rapid, shallow
A weak stimulus of the pneumotaxic center promotes what kind of breathing?
slow and deep
The apneustic center is located in the ____ pons.
lower
The apneustic center _____ the pneumotaxic center which causes inspiration.
antagonizes
What receptors are pulmonary stretch receptors?
J receptors
The action of the apneustic center is inhibited by what?
pulmonary stretch receptors/J receptors
What does the DRG do?
cause inspiration
Where is the DRG located?
Medulla
Where specifically in the medulla is the DRG located?
nucleus tractus solitarius
What does the VRG do?
causes expiration
Where is the VRG located?
medulla
Where specifically in the medulla is the VRG located?
nucleus ambiguous and nucleus retroambigus
The VRG has ___ and ___ function
inspiration and expiration
What does the VRG cause?
Expiration
When is the VRG primarily active?
expiration
What contains the pre-botzinger complex?
The Ventral Respiratory Group
Central chemoreceptors resond indirectly to what?
PaCO2
The BBB separates ___ from ____
blood from CSF
Which of the following can freely diffuse through the BBB: CO2, H+, and HCO3-?
Only CO2
After CO2 enter CSF, what does it do?
Dissociates into H+ and HCO3- (the rise in H+ is what stimulates respiration)
Respiratory changes to correct acidosis occur _____
within minutes
Can non-volatile (such as lactic acid) acids pass through BBB?
NO
How long is therapeutic hyperventilation (to reduce ICP) effective for?
A few hours to approximately 2 days
What respiratory technique is used to reduce ICP?
hyperventilation
What stimulates the central chemoreceptor?
hyeprcarbia and hypoxemia
What depresses the central chemoreceptors?
PROFOUND** hypercarbia and hypoxemia
Where are the central chemoreceptors located?
a few microns below the surface of the anterolateral aspect of the medulla
Ions, glucose, and amino acids can freely cross the BBB. T/F
False, are carried via active transport
What drives the respiratory pacemaker in the DRG?
H+
Do non-volatiles acids influence Ve on a short-term or long-term basis?
longer-term
HCO3= equilibrates between the blood & CSF - this process begins after a _____ and peaks at ____.
few hours; @2 days
What is the normal pH of CSF?
7.32
Where do peripheral chemoreceptors reside?
in the carotid bodies and aortic arch
What part of the carotid bodies do peripheral chemoreceptors reside?
bifurcation of the common carotid artery
What part of the aortic arch do peripheral chemoreceptors reside?
transverse aortic arch
What is the chief responsibility of the carotid body?
Monitor hypoxemia (PaO2 <60 mmHg)
Does the carotid body respond to SaO2 or CaO2?
No, neither - they respond to PaO2/hypoxemia
What is severed during CEA?
the afferent limb of the hypoxic ventilatory response
Why don’t we do bilateral CEA simultaneously or very close to each other?
B/c CEA severs the afferent limb of the hypoxic ventilatory response and it takes time for the body to recalibrate
What do sub-anesthetic doses of inhalation and IV anesthetics (0.1 MAC) do to the hypoxic ventilatory drive?
Depress the hypoxic ventiltory drive
What are secondary responsibilities of the carotid bodies?
monitoring of PaCO2, H+, and perfusion pressur
PaO2 <60 mmHg closes the ______ channels in ____ cells.
oxygen-sensitive K+; Type 1 Glomus
During the hypoxic ventilatory response, an action potential is propagated alon what nerve?
Hering’s nerve
Herings’s nerve –> _______ nerve
Glossopharyngeal nerve
CN 9 is what nerve?
Glossopharyngeal
The afferent pathway of the hypoxic ventilatory response terminates ______.
in the inspiratory center in the medulla
Volatile anesthetics impair ____,___,and ____ muscle function.
diaphragmatic, intercostal, and upper airway muscle function
CaO2 is reduced w/ these two processes but PaO2 usually remains normal: _____ and _____
anemia and carbon monoxide poisoning
Why does anemia and carbon monoxide poisoning not stimulate the hypoxic ventilatory response?
Even though CaO2 is reduced, PaO2 usually remains normal
Which reflex prevents alveolar overdistension?
Hering-Breuer inflation reflex
What receptors in smooth airway muscle in the lung influence respiratory pattern?
stretch receptors
What does the Hering-Breuer inflation reflex do?
Lung hyperinflation turns off the respiratory drive
What does the Hering-Breuer inflation reflex help to avoid?
overinflation
What is the Hering-Breuer deflation reflex?
Activates the respiratory drive when lung volume is too small
What does the Hering-Breuer deflation reflex help to prevent?
Atelectasis
J receptors are also known as _____ receptors
pulmonary C-fiber receptors
What increases the RR in the setting of pulmonary embolism or CHF?
J receptors (J receptors are activated by things that Jam traffic in the pulmonary vasculature).
What causes a newborn baby to take her first breath?
Paradoxical reflex of Head
What is the paradoxical reflex of head?
it causes a newborn to take its first breath
How do stretch receptors in the smooth airway muscle work?
they transduce pressure conditions inside the airway
Stretch receptors transmit pressure conditions along the _____ nerve to the _______.
vagus nerve; DRG
What is CN 10
Vagus
When does the Hering-Breuer Inflation reflex “turn off” the DRG/inspiration?
when lung inflation >1.5 L above FRC or 3x normal TV
J receptor stimulation causes _____
tachypnea
What is HPV?
A local reaction that occurs in response to a reduction in alveolar oxygen tension (not arterial PO2)
What is the goal of HPV?
To improve matching of ventilation and perfusion (aka minimize shunt)
What is the only region in the body that responds to hypoxia with vasoconstriction?
the pulmonary vasular bed
HPV is inhibited by volatile anesthetics > ____ MAC
1.5
What types of medications inhibit HPV?
phosphodiesterase inhibitors and dobutamine, vasodilators, and some CCB
Does hypervolemia or hypovolemia inhibit HPV?
Hypervolemia
_____ PEEP and _____ TV inhibits HPV.
Excessive; large
HPV is or is not inhibited by Ketamine, Propofol, and opioids?
HPV is NOT inhibited
HPV response begins within ____ and achieves full response in ____.
seconds; 15 minutes
HPV selectively increases the pulmonary vascular resistance in ______ areas to minimize shunt flow to these areas.
poorly ventilated
Neo, Epi, and Dopamine ____ shunt flow
Increase
What may distended constricted vessels in pulmonary vasculature and increase shunt flow?
Hypervolemia (LAP >25 mmHg) and elevated CO
Excessive PEEP or high TV increase what that would reduce optimal V/Q matching?
dead space
What 3 chemicals contribute to increased airway resistance?
- inositol triphosphate
- phospholipase C
- leukotrienes
The ___ of the airway has the most significant contribution to airflow resistance.
radius
What contributes to bronchoconstriction?
PNS (vagus nerve) and mast cells & non-cholinergic PNS
Non-cholinergic PNS (Nitric oxide) –> broncho____
dilation
SNS (circulating catecholamines) –> broncho____
dilation
Mast cells & non-cholingergic PNS –> broncho____
constriction
PNS (vagus nerve) –> broncho____
constriction
The vagus nerve supplies what kind of innervation to airway smooth muscle?
Parasympathetic
Stimulation of the ____ receptor produces bronchoconstriction
M3
What Mu receptor when stimulated produces bronchoconstriction?
M3
There are no sympathetic or para-sympathetic nerve endings in airway smooth muscle?
sympathetic
There is no ____ nerve endings in airway smooth muscle.
sympathetic
What receptors embedded in airway smooth muscle are activated by catecholamines in systemic circulation?
B2
Smooth muscle contraction –> _____ airway diameter
decreased
Decreased airway diameter –> increased ____
airway resistance
Smooth muscle relaxation –> ____ airway diameter
increased
The ____ nerve supplies parasympathetic innervation to airway smooth muscle.
Vagus nerve
Cholinergic nerve endings release Ach on to M3 receptors - parasympathetic or sympathetic?
Parasympathetic
What is a M3 receptor coupled to?
Gq protein
M3 receptor activation turns on the ___ protein, and this activates ____.
Gq; phospholipase C (PLC)
PLC activates what?
Inositol triphosphate (IP3) (ex of second messenger…. M3 –> PLC —> IP3)
What does IP3 stimulate and from where?
Release of Ca+2 from sarcoplasmic reticulum
Increased iCa2+ activates ____, and this enzyme enables the contractile mechanism –> bronchoconstriction.
myosin light chain kinase
Are mast cells in smooth airway epithelium?
Yes, highly concentrated
Coughing, allergy, or infection activate ____, ___, and ____, which in turn amplify the inflammatory response.
IgE, cytokines, and complement
__________-fibers release chemicals that promote bronchoconstriction.
Non-cholingergic c-fibers
Mast cell mediator?
histamine
B2 receptor is coupled to a ___ protein in airway smooth muscle
Gs
Activation of B2 receptor turns on Gs protein and this activates what?
Adenylate cyclase
Adenylate cyclase activates ____ (the second messenger)
cAMP
What does cAMP reduce?
release of Ca+2 from the sarcoplasmic reticulum
The bronchodilation pathway is turned off when _______ deactivates cAMP by converting it to AMP.
phosphodiesterase 3
NO is a potent smooth muscle ____
relaxant
Non-cholingergic PNS nerves release what onto airway smooth muscles?
vasoactive intestinal peptide
What increases NO production?
VIP
What does NO stimulate?
cGMP
What does cGMP do regarding the airway smooth muscle?
Smooth muscle relaxation and bronchodilation
What drug class is theophylline?
Methylxanthine
What drug class is zafirlukast?
Leukotriene modifier
What drug class is cromolyn?
mast cell stabilizer
What drug class is triamcinolone?
corticosteroid
What are the 3 types of pulmonary medications?
- bronchodilators
- anti-inflammatories
- methylxanthines
What are the 2 types of direct acting bronchodilators?
- beta 2 agonists
- anticholingergics
Beta __ agonists are bronchodilators
2
What are some beta 2 agonist examples?
albuterol, metaproterenol, salmeterol
What are some anticholinergics that are direct acting bronchodilators?
Atropine, glycopyrrolate, ipratropium
Anti-inflammatories that are pulmonary medications include: _____, ____, and ______.
inhaled corticosteroids, cromolyn, and leukotriene modifiers.
What are examples of leukotriene modifiers?
zileuton and montelukast
What are examples of inhaled corticosteroids?
beclomethasone, fluticasone, triamcinolone
Methylxanthines include what?
Theophylline
_____ and _____ are anesthetics with bronchodilating properties.
Volatile anesthetics and ketamine
What is the MOA of beta 2 agonists?
beta 2 stimulation –> increased cAMP –> decreased iCa2+
What are s/e of beta 2 agonists?
tachycardia, dysrhythmias, hypokalemia, hyperglycemia, tremors
Beta 2 agonists stabilize ______
mast cell membranes (which decrease mediator release)
What is the MOA of anticholingergics?
M3 antagonism –> decreased IP3 –> decreased iCa2+
What are s/e of anticholingergics?
inhibits secretions, urinary retention, blurry vision, cough
Anticholingergics increase ______ with narrow angle glaucoma.
intraocular pressure
Beclomethasone, Budesonide, Flunisolide, Fluticasone, and Triamcinolone are all what?
inhlated corticosteroids
What is the MOA of inhlaed corticosteroids?
stimulation of intracellular steroid receptors; regulates inflammatory protein synthesis (lowers airway inflammation and hyperresponsiveness)
S/e of inhaled corticosteroids?
dysphonia, myopathy of laryngeal muscles, oropharyngeal candidiasis, possible adrenal suppresion
What is the MOA of cromolyn?
Stabilizes mast cell membrane
What are the s/e of cromolyn?
neglibible s/e
Zileuton, Montelukast, Pranlukast, and Zarfirlukast are all what type of drug?
Leukotriene modifiers
What is the MOA of Leukotriene modifiers?
inhibits 5-lipoxygenase enzyme
Leukotriene modifiers decrease ____ synthesis
leukotriene
What are the s/e of leukotriene modifiers?
negligible
What is the MOA of methylxanthines?
inhibits phosphodiesterase –> increased cAMP
Theophylline is what type of drug?
methylxanthines
Methylxanthines inhibit what 2 things?
phosphodiesterase and adenosine receptors
Methylxanthines ____ endogenous catecholamine release
increase
What are the s/e of methylxanthines in plasma concentrations greater than 20?
N/V, diarrhea, HA, and disrupted sleep
When do seizures, tachydysrhythmias, and CHF occur with methylxanthine use?
plasma concentration >20
Steroids ____ arachidonic acid.
block
Which pulmonary function test is the MOST sensitive indicator of small airway disease?
Forced expiratory flow 25-75%
What measures how much air the lungs can hold at a single point in time?
Static lung volumes
What are examples of static lung volumes?
RV, ERV, TV, IRV, FRC, IC, VC, and TLC
What measures how quickly air can be moved in and out of the lungs over time?
Dynamic lung volumes
What are examples of dynamic lung volumes?
FEV1, FVC, FEV1/FVC, and MMEF
_________ measures how well the lungs can transfer gas across the alveolocapillary membrane.
Diffusing capacity
What is a normal FEV1
> 80% of predicted value
What is a normal FEV1/FVC ration?
> 75-80%
How are lung volumes and capcities measured?
spirometry
What is forced expiratory volume in 1 second (FEV1)?
volume of air that can be exhaled after a max inhalation in 1 second
FEV1 ____ with age
declines
What is forced vital capacity (FVC)?
Volume of air that can be exhaled after a max inhalation
What is the normal FVC for a male?
4.8 L
What is the normal FVC for a female?
3.7 L
What is FEV1/FVC ratio?
Compares volume of air expired in 1 second and total volume of air expired
The FEV1/FVC ratio is useful when diagnosis _____ vs _____
obstructive versus restrictive diseases
FEV1/FVC ratio <70% suggests what?
obstructive disease
A normal FEV1/FVC ratio occurs in what disease?
Restrictive
What is a normal FEV1/FVC?
> 75-80% of predicted value
What is forced expiratory flow at 25-75% vital capacity also called?
mid maximal expiratory flow rate (MMEF)
What does forced expiratory flow at 25-75% vital capacity show?
measures airflow in the middle of FEV (FEV 25-75%)
What is a normal forced expiratory flow at 25-75% vital capacity?
100 +/- 25% PREDICTED VALUE
What is maximum voluntary ventilation (MMV)?
max volume of air that can be inhaled and exhaled over the course of 1 minute
Maximum voluntary ventilation is the best test of ______-
endurance
What is the normal MMV for a male?
140-180 L
What is the normal MMV for a female?
80-120 L
What is diffusion capacity (DLCO)?
The volume of carbon monoxide that can traverse the alveolocapillary membrane per a given alveolar partial pressure of carbon monoxide
DLCO is based on _______ law
Fick’s law of diffusion
What is a normal DLCO?
17-25 mL/min/mmHg
Flow volume loops allow us to differentiate betwen what?
obstructive and restrictive respiratory diseases
On a flow-volume loop, _____ produces a waveform that moves from right to left with a negative deflection.
inhalation
On a flow-volume loop, _____ produces a waveform that moves from left to right with a positive deflection.
exhalation
What cannot be measured with spirometry.
RV
Independent risk factors that are patient-related for post-op pulmonary complication?
old age (>60)
COPD
CHF
smoking (>40 pack years)
ASA >2
Independent risk factors that are procedure-related for post-op pulmonary complication?
surgery >2 hours; GA; aortic or abdominal surgery
Independent risk factors that are diagnostic-related for post-op pulmonary complication?
Albumin <3.5 g/dL
What is a short-term benefit of smoking cessation?
reduction in carboxyhemoglobin
When should smoking cessation be done?
at least 6 weeks
What do you treat expiratory airflow obstruction with?
bronchodilators and corticosteroids
Moderate asthma, ABG analysis, and PFT have or have not been sown to increase the risk of post-op pulmonary complications for non-thoracic surgery.
HAVE NOT (key word = non-thoracic surgery)
What is smokings effects on the respiratory system?
- risk factor for pulmonary dx
- decreased mucociliary clearance
- airway hyperactivity
- reduced pulmonary immune function
What is smokings effects on the CV system?
- risk factor fo CV dx
- carbon monoxide –> decreased DO2
- catecholamine release
- coronary vasoconstriction
- decreased exercise tolerance
Short term effect of smoking cessation: carbon monoxide t1/2 = ___
4-6 hours
Short term effect of smoking cessation: P50 returns to near normal in ______
12 hours
Does short term cessation of smoking reduce pulmonary complciations?
no
Return of pulmonary function after smoking cessation takes at least ______.
6 weeks
A peak airway pressure of ____ is required to for initial reopening of the atelectatic regions.
30 cm H2O
Increasing the PIP to ____ for _____ appears to reverse anesthesia induced atelectasis almost completely.
40 cmH2O for 8 seconds (give a breath of 40 for 8 seconds)
A high FiO2 significantly contributes to what?
absorption atelectasis
Why should you use the lowest FiO2 the patient will tolerate?
B/c a high FiO2 significantly contributes to absorption atelectasis
List 3 types of surgery w/ the highest risk of PPC.
- aortic
- thoracic
- upper abdominal = neuro= peripheral vascular
A patient with severe kyphoscoliosis is expected to have a reduced ____ and ______. (pulmonary tests)
FRC; FEV1
_________ disease is characterized by small airway obstruction and increased resistance to expiratory flow.
obstructive
What type of respiratory disease has a proportionate reduction in all of the lung volumes along with poor compliance?
Restrictive
Restrictive respiratory disease has what type of lung volumes?
small
When is FEV1/FVC ratio decreased?
obstructive diseases
Patients with restrictive disease tend to have decreased ____ and ____, yet normal _____.
FEV1 and FRC; FEV1/FVE ratio
Getting air ____ is the problem in obstructive disease.
out
Restrictive or obstructive airway disease:
FEV1 ↓ to ↓↓↓↓
Obstructive
Restrictive or obstructive airway disease:
FEV1 ↓ to ↓↓↓
Restrictive
Restrictive or obstructive airway disease:
FVC ↑ to ↓↓↓
Obstructive
Restrictive or obstructive airway disease:
FVC ↓ to ↓↓↓
Restrictive
Restrictive or obstructive airway disease:
FEV1 to FVC Ratio ↓↓↓
Obstructive
Restrictive or obstructive airway disease:
FEV1 to FVC ratio normal
Restrictive
Restrictive or obstructive airway disease:
FEF 25-75% ↓↓↓
Obstructive
Restrictive or obstructive airway disease:
FEF 25-75% Normal
Restrictive
Restrictive or obstructive airway disease:
RV Normal to ↑
Obstructive
Restrictive or obstructive airway disease:
RV ↓↓↓
Restrictive
Restrictive or obstructive airway disease:
FRC Normal to ↑
Obstructive
Restrictive or obstructive airway disease:
FRC ↓↓↓
Restrictive
Restrictive or obstructive airway disease:
TLC Normal to ↑
Obstructive
Restrictive or obstructive airway disease:
TLC ↓↓↓
Restrictive
A normal spirometry waveform looks like what?
an up-side down ice cream cone
An example of a obstructive respiratory disease?
COPD
What does a spirometry waveform look like in obstructive disease?
The expiratory limb has a concave shape
LOOKS LIKE A CARRIAGE
“someone took a bite out of my ice cream cone”
What does a spirometry waveform look like in a restrictive lesion?
The shape of the loop is similar to the normal loop, but SMALLEr and RIGHT shifted
“on a restrictive diet you have to eat a smaller cone”
Pulmonary fibrosis is a ________ respiratory disease.
restrictive
In a fixed respiratory disease, the spirometry wvaeform is?
flat (both inspiratory and expiratory limbs)
“someone smashed my ice cream cone”
It needs to be fixed
What is an example of a fixed respiratory disease?
tracheal stenosis
In an extrathoracic obstruction, the patient ______ and the airway collapses.
inhales
In an extrathoracic obstruction, the patient exhales and____________.
pushes the obstruction open
What limb is flat for an extrathoracic obstruction spirometry waveform?
inspiratory limb is flat
The patient inhales and pulls open the obstruction in what type of thoracic obstruction?
intrathoracic
The patient exhales and the airway collapes in a _______obstruction.
intrathoracic
What limb is flat for an intrathoracic obstruction spirometry waveform?
expiratory limb
A bronchospasm immeditately following intubation in an asthma patient is MOST likely the result of?
Vagal stimulation
Airway smooth muscle is not innervated by the ______
SNS
What is the definition of asthma?
acute, reversible airway obstruction that is accompanied by chronic airway inflammation and bronchial hyperreactivity
With asthma, there is an acute, reversible ________, along with chronic airway and bronchial ________.
airway obstruction; inflammation; hyper-reactivity
What is atopy?
condition of being “hyper-allergic”
What is the greatest risk for developing asthma?
atopy
FEV1, FEV1/FVC ratio, and FEF 25-75% in asthma
all are reduced but improve w/ bronchodilator therapy
FEV1, FEV1/FVC ratio, and FEF 25-75% in asthma
all are reduced but improve w/ bronchodilator therapy
What is most common ABG for asthma?
respiratory alkalosis with hypocarbia
An elevated PaCO2 in asthma suggests what 3 possibilies?
- air trapping
- respiratory muscle fatigue
- impending respiratory failure
Key s/s of asthma:
wheezing, dyspnea, chest discomfort or tightness, productive or non-productive cough, prolonged expiratory phase, eosinophilia
During mechanism ventilation of an asthma patient, limit ____, prolong _____, and tolerate _____.
limit inspiratory time
prolong expiratory time
tolerate moderate permissive hypercapnia
What medications should be avoided in asthma patients?
Non-selective beta blockers and histamine releasing drugs
For asthma, use anesthetic agents that promote what?
bronchodilation
What anesthetic agents promote bronchodilation?
sevo, iso, ketamine, propofol, lidocaine
Name 4 drugs that release histamine.
- Sux
- Atracurium
- Morphine
- Meperidine
Smooth muscle hypertrophy, fibrosis, angiogenesis, and hypersecretion of mucus occur in what?
asthma
What type of external stressors provoke asthma S/S?
vagal stimulation and cold air
What drugs provoke asthma S/S? (4 total)
aspirin, nsaids, beta blockers, sulfites
What might the EKG show during a severe asthma attack?
RV strain with right axis deviation
Why might an EKG show RV strain with right axis deviation during a severe asthma attack?
PVR increases, and this increases workload of right heart
In asthma, PVR increases or decreases?
increases
The tachypnea and hyperventilation that occur during asthma attacks are the result of what?
Neural reflexes
Why might severe bronchospasm cause hypoxemia?
V/Q mismatch
PFTs are or are not predictive of post-op pulmonary complications.
ARE NOT
For what one surgery are PFT predictive of post-op pulmonary complications?
Lung reduction surgery
In asthma _____ may increase due to air trapping, but ______remains WNL.
FRC; TLC
CXR of asthma?
hyper-inflated lungs w/ diaphragmatic flattening
What is the preferred extubation technique for asthma patients?
Deep extubation (if not possible, use lidocaine or opioids)
What might benefit a patient with exercise-induced asthma during ventilation?
HME
What volatile agent reduces the risk of coughing and risk of bronchospasm?
Sevo
What is the only IV induction drug that causes bronchodilation?
Ketamine
What IV induction drug suppresses airway reflexes?
Propofol
_________1-3 minutes before extubation suppresses airway reflexes.
Lidocaine 1-1.5 mg/kg
How do you differentiate between light anesthesia and bronchospasm?
NMBD improve pulmonary compliance with light anesthesia but NOT bronchospasm
What is ketorolac’s effect on the airway?
it can increase airway resistance (caution in asthma)
What histamine receptor, when stimulated, reduces histamine release?
Presynaptic H2 receptor
What are some H2 antagonists?
Ranidtine and Famotidine
H2 antagonists allow for unopposed H1 stimulation, which can cause what in asthma patients?
bronchospasm (very low risk)
What BB is the best choice in asthma patients and why?
Esmolol b/c of its short t1/2 and B1 selectivity
What is F2 alpha prostaglandin?
a naturally occuring hormone
What does carboprost (hemabate) mimic?
the action of F2 alpha prostaglandin
What is the use of carboprost (hemabate)?
it is used to stop uterine bleeding
What is a s/e of carboprost (hemabate)?
bronchoconstriction in asthmatics
Which drug is LEAST likley to be effective in relieving s/s of acute bronchospasm?
1. Ketamine 1 mg/kg IV
2. Epi 1 mcg/kg IV
3. Hydrocortisone 2 mg /kg IV
4. Lidocaine 1.5 mg /kg IV
Hydrocortisone 2 mg /kg IV
What are causes of wheezing, besides asthma, when ventilated?
Kinked ETT, end-bronchial intubation, pulmonary aspiration
How does intraoperative bronchospasm present?
- wheezing
- decreased breath sounds
- increased PIP (/t decreased dynamic compliance)
- increased alpha angle on ETCO2 waveform
How do you treat acute bronchospasm?
100% FiO2, deepen anesthetic
short acting inhaled B2 agonist
inhaled ipratropium
epi 1 mcg/kg IV
hydrocortisone 2-4 mg /kg IV (doesn’t treat, prevents additional problems)
aminophylline
helium -oxygen gas mix
Name differential diagnosis for intra-op bronchospams/wheezing:
- mechanical obstruction of ETT
- light anesthesia
- acute asthma attack
- endobronchial intubation
- pneumo
- aspiration
- pulmonary edema
- PE
With light anesthesia, coughing and straining occur. This ____ FRC.
Decreases
Name 4 mechanical obstructions of ETT.
kinking, biting, secretions, overinflation of cuff
Why do increased PIP with normal plateau pressures occur during bronchospam?
d/t decreased dynamic pulmonary compliance
During bronchospasm, PIP is ____ and plateua pressure is _______
PIP is increased; plateau is normal
Is montelukast used in the treatment of acute bronchospasm?
NO
Alpha-1 antitrypsin deficiency: (select 2).
1. increases the risk of bronchospasm
2. causes pan-lobular emphysema
3. can be treated with IgG
4. is the most common metabolic disease affecting the liver
2 & 4
Pan-lobular emphysema and most common metabolic dx affectign the liver
COPD is characterized by a reduction in ___________ and a slower forced emptying of the lungs.
maximal expiratory flow
How is COPD different than asthma?
Air flow obstruction is not fully reversible
COPD is an umbrella term for what two diseases?
Chronic bronchitis and emphysema
What is the pathophysiology of chronic bronchitis?
hypertrophied bronchial mucus glands and chronic inflammation
What is the pathophysiology of emphysema?
enlargement and destruction of the airways distal to the terminal bronchioles
Etiologies of COPD include ____, ____, ____, and ____.
smoking, respiratory infection, exposure to environmental pollutants, and alpha-1 antitrypsin deficiency
Alpha-1 antitrypsin deficiency is r/t what disease?
COPD
Inability to fully exhale —> _____
gas trapping (↑RV)
ABG of chronically elevated PaCO2
respiratoyr acidosis
To combat respiratory acidosis, what do the kidneys do?
reabsorb bicarb
What happens if you administer supplemental O2 to patient with severe COPD?
it can cause oxygen-induced hypercapnia
