Final Exam Review Flashcards
Adult larynx anatomic location
Anterior to C3-C6
At birth larynx anatomic location
C3-C4
Larynx lies between ___ and ___
Pharynx and trachea
Normal A-O extension
35 degrees
Mallampati Classification
Pt sitting, neck extended, mouth fully opened, tongue protruded, no phonation
MP Classes 1-4
MP Class 1
Full view of uvula and tonsillar pillars, soft palate
MP Class 2
Partial view of uvula or uvular base, partial view of tonsils, soft palate
MP Class 3
Soft palate only
MP Class 4
Hard palate only
Sphenopalatine ganglion—middle division of CN ___ and innervates what 4 structures?
Middle division of CN V
- Nasal mucosa
- Superior pharynx
- Uvula
- Tonsils
Glossopharyngeal nerve innervation
CN IX
- Posterior 1/3 of tongue
- Pharyngeal, tonsillar nerves
- Oral pharynx
- Supraglottic region
Internal branch of superior laryngeal nerve
CN X
- Mucus membrane above the vocal cords
- Glottis
Recurrent laryngeal nerve
CN X
-Trachea below the vocal cords
Superior laryngeal nerve is a branch of what cranial nerve?
Vagus nerve (CN X)
The superior laryngeal nerve divides into what two nerves?
- Internal superior laryngeal nerve
- External superior laryngeal nerve
Internal SLN
- Provides sensation to supraglottic and ventricle compartment
- Stimulation causes laryngospasm!
Stimulation of internal SLN causes ___
LARYNGOSPASM
External SLN provides ___ innervation to what muscle?
Motor innervation to cricothyroid muscle
Recurrent laryngeal nerve is a branch of what cranial nerve?
Vagus nerve (CN X)
Left RLN passes @ ___
Aortic arch
Recurrent laryngeal nerve provides sensory innervation to ___
Infraglottis
Recurrent laryngeal nerve provides motor innervation to all of the larynx except for the ___ muscle
Cricothyroid muscle
Stimulation of the recurrent laryngeal nerve causes ___
Abduction of vocal cords
Damage to the recurrent laryngeal nerve causes ___
Vocal cord adduction
What is the trachea?
Flexible cylindrical tube supported by 20-25 C-shaped cartilages
Diameter of the trachea
18-20 mm diameter
Length of trachea
12.5-18 cm length
Trachea extends from ___ to ___
C6 to T5
Where does the trachea divide into 2 bronchi?
At carina (level T5-T7); 25 cm from teeth
Inspiration is the ___ phase of breathing cycle
Active phase
What nerve transmits motor stimulation to diaphragm?
Phrenic nerve—C3, C4, C5
What nerves send signals to the external intercostal muscles?
Intercostal nerves (T1-T11)
The act of inhaling is ___
Negative-pressure ventilation
Transpulmonary pressure is the pressure difference between ___ and ___
Alveolar pressure and pleural pressure on outside of lungs
Alveoli tend to collapse together while the pleural pressure attempts to pull outward
What is recoil pressure?
The elastic forces which tend to collapse the lung during respiration
4 volumes of spirometry
- Tidal volume (TV)
- Inspiratory reserve volume (IRV)
- Expiratory reserve volume (ERV)
- Residual volume (RV)
Tidal volume (TV)
Amount of inspired air with a normal breath; amounts to about 500 ml in the avg adult male
Inspiratory reserve volume (IRV)
Extra volume of air that can be inspired over and above the normal tidal volume when the person inspires with full force; usually equals 3000 ml
Expiratory reserve volume (ERV)
Maximum extra volume of air that can be expired by forceful expiration after the end of a normal tidal expiration; about 1100 ml
Residual volume (RV)
Volume of air remaining in the lungs after the most forceful expiration; about 1200 ml
4 capacities of spirometry
- Inspiratory capacity (IC)
- Functional residual capacity (FRC)
- Vital capacity (VC)
- Total lung capacity (TLC)
Inspiratory capacity (IC) =
TV + IRV
The amount of air a person can breathe in, beginning at the normal expiratory level and distending the lungs to the maximum amount ~3500 ml
Functional residual capacity (FRC) =
ERV + RV
The amount of air that remains in the lungs at the end of normal expiration ~2300 ml
Vital capacity (VC) =
TV + IRV + ERV
The maximum amount of air a person can expel from the lungs after first filling the lungs to their maximum extent and then expiring to the maximum extent ~4600 ml
Total lung capacity (TLC) =
VC + RV
TV + IRV + ERV + RV
Max volume to which the lungs can be expanded with the greatest possible effort ~5800 ml
IC =
IRV + TV
FRC =
ERV + RV
VC =
IRV + ERV + TV
TLC =
IRV + TV + ERV + RV
TV ~
~500 ml
IRV ~
~3000 ml
ERV ~
~1100 ml
RV ~
~1200 ml
IC ~
~3500 ml
FRC ~
~2300 ml
VC ~
~4600 ml
TLC ~
~5800 ml
Spirometry cannot measure ___
Residual volume (RV)
Thus FRC and TLC cannot be determined using spirometry alone
FRC and TLC can be determined by ___, ___, and ___
- Helium dilution
- Nitrogen washout
- Body plethysmography
What are 3 main functions of surfactant?
- Lowers surface tension of alveoli and lung—increases compliance of lung; reduces work of breathing
- Promotes stability of alveoli—alveoli have tendency to collapse; surfactant reduces forces causing atelectasis
- Prevents transudation of fluid into alveoli—reduces surface hydrostatic pressure effects; prevents surface tension forces from drawing fluid into alveoli from capillary
What type of cells secrete surfactant?
Type II pneumocyte
Very important in neonates—maturation occurs at 24 weeks gestation
What forces air out of alveoli?
Elastic force caused by water tension attempts to force air out of alveoli
Poiseuille’s Law—reducing the radius by 16% will ___ the resistance
Double
Poiseuille’s Law—reducing the radius by 50% will increase resistance ___
16-fold (2^4)
If you double the radius, you reduce the resistance ___
16-fold (2^4)
Systemic circulation = ___ pressure, ___ flow, ___ resistance
High pressure, low flow, high resistance
Pulmonary circulation = ___ pressure, ___ flow, ___ resistance
Low pressure, high flow, low resistance
RA pressure
2-3 mm Hg
RV pressure
25 mm Hg
LA pressure
5-8 mm Hg
LV pressure
120 mm Hg
Mean pulmonary artery pressure
14-15 mm Hg
Mean systemic artery pressure
90-100 mm Hg (120/80)
Mean pulmonary capillary pressure
10-10.5 mm Hg
Mean systemic capillary pressure
20 mm Hg
What is recruitment?
Opening of previously closed vessels
What is distention?
Increase in caliber of vessels
What is the CHIEF mechanism for fall in pulmonary vascular resistance (PVR)?
Recruitment
However, both recruitment and distention are two mechanisms that decrease PVR
Increased CO ___ pulmonary vascular pressures but ___ pulmonary vascular resistance
Increases pulmonary vascular pressures but decreases pulmonary vascular resistance (occurs during periods of stress and increased tissue oxygen demand)
___% of alveolar surface area is covered by capillary bed
70-80%
Total capillary surface area almost equals alveolar surface area
Capillary volume increases by ___
Recruitment—opening closed segments
What is the normal capillary volume at rest?
70 ml (1 ml/kg body weight)
What is the maximal capillary anatomical volume?
200 ml
Distance RBCs have to travel through capillary network is ___
Small (600 to 800 micrometers)
Capillary network blood volume = ___ stroke volume
RV
Total blood volume from main pulmonary artery to left atrium is ___ ccs
500
Lung is ___% blood by weight
40-50%; this volume fraction > than any other organ
What is the capacitance reservoir for the left atrium?
The pulmonary vasculature—can act as a reservoir and alter its volume from 50 to 200% of resting volume
Can store blood in the lungs so that the LV doesn’t run dry as it pumps out to the systemic circulation
Inspired air O2/CO2 concentrations
PO2 150 mm Hg
PCO2 0 mm Hg
RBC/alveolar O2/CO2 concentrations
PO2 = 100 mm Hg PCO2 = 40 mm Hg
Deoxygenated blood O2/CO2 concentrations
PO2 = 40 mm Hg PCO2 = 46 mm Hg
Lung Zone 1
alveolar flow > pulmonary artery pressure > pulmonary vein pressure
very negligible blood flow through this area of the lung; can ventilate it all day long, but it’s not doing any gas exchange
Lung Zone 2
pulmonary artery pressure > alveolar pressure > pulmonary vein pressure
might get intermittent flow/exchange through zone 2 with changes in systolic/diastolic pressure during inhalation/exhalation; not a lot of flow/exchange going on here
Lung Zone 3
pulmonary artery pressure > pulmonary vein pressure > alveolar pressure
maximizes both blood flow and gas exchange because you have uninterrupted alveolar interfaces
Blood vessels are more distended at the ___ of the lung
Base
___ resistance to flow in the base of the lung
Decreased
___ (higher/lower) blood flow at the base of the lung
Higher
Higher ___ pressures in apex of lung than capillary pressures
Higher alveolar pressures; causes decreased perfusion in apex of lung
What are 3 ways to expand zone 1?
- Decreased pulmonary artery pressure (i.e.: shock, hypovolemia)
- Increased alveolar pressure (i.e.: PEEP)
- Occlusion of blood vessels (i.e.: pulmonary embolism)
What are 2 ways to reduce zone 1?
- Increased pulmonary artery pressure (i.e.: infusion of fluid or blood)
- Reduced hydrostatic effect (i.e.: change patient position; standing to supine)
V/Q ratio is ___ in the upper lung
High
Because you have ventilation, but no perfusion
V/Q ratio is ___ in the lower lung
Low
Because you have good ventilation & perfusion in the bases of the lungs
What are 4 things that cause vasoconstriction of the pulmonary vasculature?
- Reduced PaO2
- Increased PCO2
- Thromboxane A2
- Histamine
What are 3 things that cause vasodilation of the pulmonary vasculature?
- Increased PaO2
- Prostacyclin
- Nitric oxide
High CO2 =
Vasoconstriction
Why we hyperventilate neurosurgery patients…because low CO2 = vasodilation
Thromboxane A2 is a ___
Potent vasoconstrictor
Thromboxane A2 is produced during…
Produced during acute lung tissue damage by
macrophage, leukocytes, and endothelial cells
Effect localized to injured region because half-time of thromboxane inactivation is only seconds
Body’s way of protecting itself when the lung is injured
Prostacyclin is a ___
Potent vasodilator
Prostacyclin inhibits ___
Platelet activation
Nitric oxide is a ___
Epithelial vasodilator
Nitric oxide has a ___ effect
Strictly localized effect (only works where it is produced)
Nitric oxide is produced from ___
L-arginine
How does nitric oxide cause vasodilation?
Nitric oxide activates guanylyl cyclase, which produces cyclic GMP…cyclic GMP causes smooth muscle relaxation
Nitric oxide is delivered via ___
Inhalation technique
Nitric oxide is very ___ at high concentrations
Toxic
Nitric oxide binds ___ to hemoglobin
Irreversibly
Nitric oxide binds to hemoglobin ___ x’s greater than oxygen
200,000x’s greater
Alveolar hypoxia produces ___
Hypoxic pulmonary vasoconstriction (HPV)
HPV is a ___ response
Localized response of pulmonary arterioles
HPV is caused by ___ and enhanced by ___ and ____
Hypoxia; enhanced by hypercapnia and acidosis
HPV is a mechanism of balancing ___ ratio
V/Q
HPV causes a shift of flow to ___
Better ventilated pulmonary regions
Normal alveolar PO2 is ___
100 mm Hg
Normal alveolar PCO2 is ___
40 mm Hg
Alveolar PCO2 ___ in proportion to CO2 excretion
Increases
As alveolar ventilation increases, PCO2 ___
Decreases (inverse relationship; O2 has direct relationship with alveolar ventilation)
Normal CO2 production at rest is ___
200 ml/min
Expired air is a combination of ___ air and ___ air
Dead space air and alveolar air
First portion of expired air = dead space air; consists of humidified air
Second portion of expired air = mixture of both dead space and alveolar air
Alveolar air is expired at the end of ___
Exhalation
What 4 factors affect diffusion? (according to Fick’s Law)
- Cross sectional area of membrane
- Partial pressure differences
- Gas coefficient
- Tissue thickness
Increase in:
-Cross sectional area
-Partial pressure difference (concentration gradient)
-Gas coefficient
INCREASE rate of diffusion; all are directly related to rate of diffusion
Tissue thickness is inversely related to rate of diffusion (thicker tissue = slower rate of diffusion)
V/Q is normal when…
Alveolar ventilation and blood flow are both normal
V/Q = zero
Ventilation = zero but perfusion is present (i.e.: complete airway obstruction)
V/Q = infinity
If ventilation is present but there is no perfusion (i.e.: pulmonary artery obstruction)
If V/Q ratio is zero or infinity, there is ___
No exchange of gases
Physiologic shunt—V/Q is ___
Below normal
Shunt =
Perfusion but no ventilation…blood is being shunted from pulmonary artery to pulmonary vein without participating in gas exchange
Shunted blood is not ___
Oxygenated
The greater the physiologic shunt, the greater the…
Amount of blood that fails to be oxygenated in the lungs
Physiologic dead space—V/Q is ___
Greater than normal
Dead space =
Ventilation but no perfusion…more available oxygen in alveoli than can be transported away by flowing blood
Physiologic dead space includes ___ and ___
- Wasted ventilation
- Anatomical dead space
When physiologic dead space is great, much of the work of breathing is wasted effort because ___
Ventilated air does not reach blood
SaO2 100%, PaO2 ___
100+
SaO2 95%, PaO2 ___
75
SaO2 90%, PaO2 ___
60
SaO2 75%, PaO2 ___
40 (mixed venous blood in pulmonary artery)
SaO2 60%, PaO2 ___
30
SaO2 50%, PaO2 ___
27
Very rough rule—PaO2 40, 50, 60 for sat ___, ___, ___
70, 80, 90
Hemoglobin-oxygen equilibrium curve is affected in two ways:
- Shift in position (left or right)
- Change in shape
What indicates a greater interference with O2 transport—a change in position or shape?
Change in shape
Change in shape of the HbO2 equilibrium curve is d/t change in ___
Hemoglobin
Right shift of Hb-O2 dissociation curve—Hb has ___ affinity for O2, ___ O2, saturation will be ___ for a given PO2
Hb has less affinity for O2, releases O2, saturation will be less for a given PO2
Left shift of Hb-O2 dissociation curve—Hb has ___ affinity for O2, ___ O2, saturation will be ___ for a given PO2
Hb has higher affinity for O2, binds O2, saturation will be higher for a given PO2
4 causes of right shift:
- Increased CO2
- Increased temp
- Decreased pH/increased H+
- Increased 2,3 DPG
3 causes of left shift:
- Increased pH
- Decreased temp
- Decreased 2,3 DPG
What is the Bohr effect?
Shift to the right d/t increase H+
What has the greatest effect on the Hb-O2 dissociation curve?
A change in shape (so a change in hemoglobin) has the greatest effect on the curve than does any shift change (right or left)
CaO2 =
O2 content in the blood…the sum of O2 carried on Hb and dissolved in plasma
Formula for CaO2 =
(SaO2 x Hb x 1.31) + (PO2 x 0.003)
1.31 =
ML of oxygen bound to one gram of hemoglobin
0.003 =
O2 dissolved in 100 ml plasma…very small amount of oxygen dissolved in plasma
Most CO2 is transported as ___
Bicarbonate (HCO3-)
DRG or VRG controls respiration?
DRG
What two cranial nerves deliver sensory information to the DRG?
- Glossopharyngeal (CN IX)
- Vagus (CN X)
DRG receives signals from what 3 sources?
- Peripheral chemoreceptors
- Baroreceptors
- Lung receptors
VRG is ___ during normal respiration
Inactive; only becomes active during exercise
What is the chemosensitive area of the brainstem?
Highly sensitive area on ventral medulla surface; contains central chemoreceptors
Chemosensitive area of brainstem is responsive to changes in ___ or ___
Blood PCO2 or H+ ion concentration
Effect of CO2 on respiratory center activity
Increased CO2 = increased respiratory center activity
CO2 has potent direct effect via ___ on the chemosensitive area
H+
CO2 is highly permeable to blood-brain barrier, so blood and brain concentrations are ___
Equal
How does CO2 form H+ ions?
CO2 + water —> carbonic acid, dissociates into H+ and bicarbonate ions in medulla/CSF
Released H+ ions in brain stimulate respiratory center activity
CO2 diffuses ___ faster than oxygen does
20x’s faster
What has greater effect on alveolar ventilation—change in PCO2 or change in pH?
PCO2
Ventilation is greatly increased with blood PCO2 above ___
35 mm Hg—steep part of curve
Chemoreceptors are located in ___ and ___
Carotid and aorta
Peripheral chemoreceptors are stimulated by ___
Hypoxemia
Where are the carotid bodies located?
Bifurcations in common carotid
Carotid bodies innervation to DRG
CN IX (glossopharyngeal)
Where are the aortic bodies located?
Aortic arch
Aortic bodies innervation to DRG
CN X (vagus)
Central chemoreceptors are located in the ___
Chemosensitive area of brainstem
Peripheral chemoreceptors are located in ___ and ___
Carotid and aortic bodies
Stimulation of chemoreceptors is caused by ___
Decreased arterial oxygen content
Ventilation doubles when PaO2 falls below ___
60 mm Hg
High risk PFT results—FEV1 < ___
FEV1 < 2L
High risk PFT results—FEV1/FVC < ___
FEV1/FVC < 0.5
High risk PFT results—VC < ___ in adult; VC < ___ in child
VC < 15 cc/kg in adult; VC < 10 cc/kg in child
High risk PFT results—VC < ___
40 to 50% of predicted
Intubation criteria—mechanics: RR > ___, VC < ___, NIF ___
RR > 35
VC < 15 cc/kg adult or < 10 cc/kg child
NIF less negative than -20 cm H2O
Intubation criteria—PaO2 < ___ on FiO2 40%
PaO2 < 70 mm Hg on FiO2 40%
Intubation criteria—PaCO2 > ___
PaCO2 > 55 (except in chronic hypercarbia)
Intubation criteria—Vd/Vt > ___
Vd/Vt > 0.6 (remember, normal dead space is 30%)
Intubation criteria—clinical status (6)
- Airway burn
- Chemical burn
- Epiglottitis
- Mental status change
- Rapidly deteriorating pulmonary status
- Fatigue
Increase of PCO2 by 10 mm Hg causes a decrease in pH by ___
0.08
Likewise, a decrease of PCO2 by 10 mm Hg will increase pH by 0.08
So an acute increase in CO2 to 60 should cause a drop in pH to 7.24 (consider normal PCO2 is 40)
Hypoxemia =
Decrease PO2 in blood, < 75
Hypoxia =
A low O2 state
A-a gradient is a measure of ___
Efficiency of lung
How to calculate PaO2 (formula)
PaO2 = (PB - PH2O) x (FiO2) - (PaCO2/0.8)
PB = atmospheric pressure, 760 mm Hg PH2O = vapor pressure, 47 mm Hg
Normal A-a is approximately ___
Age/3
A-a gradient is ___ during anesthesia and with intrinsic lung disease (i.e.: PTX, PE, shunt, V/Q mismatch, diffusion problems)
Widened
A-a gradient is normal with ___ or ___
Hypoventilation or low FiO2
Treatment of hypoxemia/hypoxia
TREAT UNDERLYING CAUSE!!!
A decrease in bicarbonate by 10 mmoles decreases pH by ___
0.15
An increase in bicarbonate by 10 mmoles increases pH by 0.15
A bicarbonate of 13 would result in a pH of 7.25 (consider normal bicarbonate is 23)
Total body bicarbonate deficit =
Base deficit x weight in kg x 0.4; in meq/L
Usually replace 1/2 bicarbonate deficit
Pulse ox is a ___ intraoperative monitor
Mandatory
940 nm =
Infrared light, oxyhemoglobin
660 nm =
Red light, deoxyhemoglobin
What 2 hemoglobin variants affect pulse oximetry?
Carboxyhemoglobin (COHb)
Methemoglobin (MetHb)
Carboxyhemoglobin shows a SPO2 of ___
100%—overestimation of true oxygenation
What is used to distinguish between CO and oxygen levels?
Co-oximetry
Cyanosis is seen in methemoglobinemia when ___ of Hb is in methemoglobin form
15%
Methemoglobin shows a SPO2 of ___
85%
Treatment of methemoglobinemia
Methylene blue or ascorbic acid
What two things do NOT affect pulse oximetry?
Fetal hemoglobin and bilirubin
Capnography indicates ___ but does not reliably detect ___
Esophageal intubation; endobronchial intubation
What is the gold standard for tracheal intubation?
+ ETCO2
Capnometer
Measures CO2
Capnograph
Records and displays CO2
CO2 are depicted graphically as a ___
Capnogram
CO2 is recorded by a ___
Capnograph
CO2 is measured by a ___
Capnometer
What point on the capnograph is the recorded ETCO2?
D point
In the awake and lateral position, the ___ lung is better perfused and ventilated
Dependent
Under anesthesia with a decrease in FRC, the ___ lung ventilates more
Upper lung; creates a V/Q mismatch
What are 6 factors that inhibit hypoxic pulmonary vasoconstriction?
- Very high or very low PA pressures
- Hypocapnia
- High or very low mixed venous PO2
- Vasodilators—NTG, Nitroprusside (SNP), beta-adrenergic agonists (dobutamine), calcium channel blockers
- Pulmonary infections
- Inhalation agents
How does Hypocapnia affect HPV?
Inhibits HPV
How do vasodilators like NTG and Nitroprusside (SNP) affect HPV?
Inhibit HPV
How do inhalation agents affect HPV?
Inhibit HPV
What do you want to set the FiO2 for one lung ventilation?
80-100%
Tidal volumes for one lung ventilation
10cc/kg
What do you use to ensure proper ETT placement during one lung ventilation?
Fiber optic scope
Where do you want to keep PaCO2 during one lung ventilation?
Keep PaCO2 at 40 mm Hg
Add 5 cm H2O CPAP to ___ lung
Nondependent (upper) lung—warn surgeon
Add 5 cm H2O PEEP to ___ lung
Dependent lung—treats atelectasis but may increase vascular resistance
Increase both CPAP and PEEP ___ during one lung ventilation
Slowly
During apnea, PCO2 increases ___ mm Hg for the first minute and then ___ mm Hg for each additional minute of apnea
5 mm Hg for first minute; 3 mm Hg for each additional minute
Example: if PCO2 was 40, then after 10 minutes of apnea, the PCO2 will be 72.
Progressive respiratory acidosis limits hypoxia during one lung ventilation to ___ minutes
10-20 minutes
First most sensitive sign of MH =
Unexplained tachycardia
Most specific sign of MH =
Increasing ETCO2–hypercapnia 2-3x normal
Initial ABG for MH
Initial metabolic acidosis, then a combined metabolic and respiratory acidosis
Dantrolene dosage for MH
2.5 mg/kg every 5 minutes
Max dose of dantrolene for MH
10 mg/kg
After MH has subsided, continue to give how much dantrolene?
1 mg/kg every 6 hours for 72 hours
What should not be given to the MH patient while on dantrolene?
Calcium channel blockers—can cause life-threatening hyperkalemia/myocardial depression
Persistent ventricular arrhythmias during MH should be treated with ___
Procainamide…NOT calcium channel blockers
How does dantrolene work?
Muscle relaxant that works directly on the ryanodine receptor to prevent the release of calcium—it inhibits Ca release from the sarcoplasmic reticulum
What drugs cause MH?
All inhalation agents (except nitrous) and succs (depolarizing muscle relaxant)
Does propofol cause MH?
No!
Do non-depolarizing muscle relaxants cause MH?
No! Depolarizing muscle relaxant SUCCS does cause MH
What is the gold standard pre-op test for MH?
Muscle biopsy with halothane-caffeine contracture test—78% specific, 97% sensitive
Caffeine causes muscle to contract
Halothane in the MH patient causes more forceful contraction
Does a prior uneventful general anesthetic rule out the possibility of MH?
NO!
Who has the highest MAC requirement?
Term infant to 6 months of age
Hyperthermia ___ MAC
Increases
Chronic EtOH abuse ___ MAC
Increases
Hypernatremia ___ MAC
Increases
Drugs that increase CNS catecholamines ___ MAC
Increase
Pregnancy ___ MAC
DECREASES
Hypothermia ___ MAC
Decreases
For every 1 deg C drop in body temp, MAC decreases 2 to 5%
Acute EtOH ingestion ___ MAC
Decreases
What are 5 factors that have NO EFFECT on MAC?
- Thyroid gland dysfunction
- Duration of anesthesia
- Gender
- Hyper/hypokalemia
- Hyper/hypocarbia
What is the second gas effect?
Large volume uptake of a first gas (nitrous) accelerates the delivery of a second gas, thus speeding induction
What is diffusion hypoxia?
Large amount of nitrous dilutes alveolar O2 concentration, causing hypoxia
High risk pts for diffusion hypoxia?
Patients with a concurrently decreased FRC:
- Pregnancy
- Obesity
- Children
How can you avoid diffusion hypoxia?
Administer 100% O2 following N2O use
Nicotine from smoking stimulates ___
Sympathetic ganglia—catecholamine release
Nicotine causes catecholamines to be released from ___
Adrenal medulla
Increase HR, BP, and SVR
Sympathetic stimulation from nicotine persists ___ after last cigarette
30 minutes
How does smoking irritate the airway?
- Increased mucus production
- Decreased ciliary clearance
- Increased inflammation
- Reduced surfactant
What should you, the anesthesia provider, do when prepping a case for a smoker?
Pre-oxygenate well and avoid instrumentation of airway until deep level of anesthesia is achieved
Advise smokers to stop smoking at least ___ prior to surgery
12 hours
If patient stops smoking night before surgery (12-24 hours), COHb and nicotine levels will be reduced to that of ___
Non-smokers
Airway reactivity decreases after ___ days of cessation
2 days
Airway reactivity is near the level of a non smoker after ___ days of cessation
10 days
Cessation of > 8 weeks will reduce ___
Post-op pulmonary complications
Cessation of > 2 years will reduce risk of ___
MI to that of nonsmoking population
Severe emphysema requires longer ___
Expiratory times
Normal I:E is 1:2, so in COPD —> 1:3
Closely monitor ___ to avoid rupturing an emphysematous blob or bullae, PTX
Peak inspiratory pressures (PIP)
CO2 retainers—ETCO2 should be kept near ___; a rapid correction will lead to ___
The patient’s baseline; metabolic alkalosis
Caution using ___(what inhalation gas) in COPD patients; may expand bullae and worsens pulmonary HTN
Nitrous oxide
What 2 inhalation agents could cause airway stimulation and should not be used in COPD patients?
- Desflurane
- Isoflurane
What is worsened after inhalation agents?
Mucociliary clearance—results in lots of secretions…suction ETT frequently
Avoid ___ to prevent bronchospasm in COPD patients
Histamine releasing drugs—Pentothal (STP), morphine, atracurium, mivacurium, neostigmine
Treat patient with ___ to minimize chance of bronchospasm, especially before extubation
Nebulized albuterol
