Respiratory Flashcards
When comparing base of lung to apex, the base lung has …
Smaller alveoli
Grater compliance
Low V/Q ratio
Less negative intrapleural pressure
Respiratory center and their location in CNS?
Inspiration center ->
Expiration Center ->
Apneustic Center ->
Pnumotoxic Center ->
Inspiration center -> Medulla
Expiration Center -> Medulla
Apneustic Center -> Lower Pons
Pnumotoxic Center -> upper Pons
What respiratory center responsible for basic rhythm of respiration ?
Medullary inspiration center
Biots’ breathing is …. and caused by …
Quick shallow respiration followed by apnea.
Injuries to Medulla
Cheyne strike breathing is … and caused by …
Periods of apnea and hyperapnea
Sleep, high altitude, morphine, CHF, brain injury/tumor, metabolic encephalopathy, CO poisoning
Deep, Labored breathing is …
Kusmual breathing, caused by DKA
What stimulates respiration at the central chemoreceptors level?
CNS H+ and HC3 ions (not peripheral H because it won’t cross BBB)
CO2 -> diffuses to CSF through BBB and forms carbonic acid -> then it dissociates into H+ and HC3 which they stimulates chemoreceptors
Peak airway pressure originated from ….
Plateau pressures originated from ….
Large airways
Pressure measured at alveolar level
Static compliance is
Static -> plateau airway pressure
- it is pulm compliance during period without gas flow
e. g. inspiratory pause
C (stat) = VT/Pplat - PEEP
Total compliance =
1/TC = 1/Cw + 1/CL
CT= Total compliance Cw = chest wall compliance CL= lung compliance
Dynamic compliance is …
Dynamic-> peak airway pressure
- it represents pulm compliance during period of gas flow
e. g. inspiration period
Cdyn = VT/PIP -PEEP
Pulm fibrosis or emphysema increases pulm compliance?
Emphysema-> increases compliance
Fibrosis-> decreases it
How would hyperbaric O2 increases O2 content?
By increasing the amount of dissolved O2
CO2 carried in blood by 3 forms …
Dissolved 10%
Carbamino compound 30%
HCO3 60%
The buffers in
Blood ->
Interstitial fluid ->
Intercellular fluid ->
Blood -> plasma protein, Hgb, HCO3
(Hgb has greater buffering capacity than HCO3 in blood) gap in knowledge 2010
Interstitial fluid -> HCO3
Intercellular fluid -> protein & Po4
Deoxygenated blood that increases its ability to carry CO2 in peripheral tissue is … effect
Haldane
Effect PaCO2 on OxyHgb dissociation curve is …. effect
Bohr
The primary contributor to the venous admixture or physiological shunt is …. vessels
Bronchial
Coronary sinus drains into …. atrium. And dose or Diane not contribute to physiological shunt?
Right atrium
Dose not
…. vessels drains directly into chambers of the heart and contribute to the physiological shunt.
Thebesian vessels
FRC measured by
Body plethysmography and helium dilution technique
Stopping smoking a week before surgery will decrease … and this will increase…..
Carbon monoxide level
Increases P50 and O2 carrying capacity
Where other pulm function needs longer period of stopping smoking to return to normal.
What is the difference between measured arterial PaCO2 and exhaled CO2 is ….
Physiological dead space.
Dead space increases or decreases with the following
Age
Neonates
Pregnancy
Obesity
Increases in elderly (keyword)
All others are similar compared to adults ???
FRC increases or decreases in following
Neonates Obesity Pregnancy Supine GA Emphysema
All decrease Except emphysema (increases FRC)
What is the volume refer too where the small airway begins to close?
Closing capacity
What is the primary etiology for hypoxemia in obese and elderly patients?
Closing capacity approaches the FRC during tidal ventilation
FRC and closing capacity in elderly vs obesity
Elderly
FRC -> normal/increase
CC -> increases
Obesity
FRC -> decreases
CC -> normal
PEEP increases …. and decreases …
FRC
Dead space
Pulm compliance
RV afterload
It decreases
- venous return
- pulm artery occlusion pressure (LV afterload).
Pulm mechanics in elderly?
Increase
- lung compliance
- FRC
- RV
- anatomical dead space
- closing capacity
- pulm vascular resistance
- pulm artery pressure
Decreases
- chest wall compliance
- VC
- diffusion capacity
- PaO2
- hypoxia pulm vasoconstriction
- ventilatory response hypoxia & hypercarbia
Closing capacity dose not increase in obesity, but it dose in …
Elderly
What you expect lung volumes changes in obesity?
Why shunt increases in obesity although closing capacity stays the same in obesity?? (Gap x2)
FRC, ERV, VC, and TLC -> decreases
RV, Dead space space, and closing capacity-> unchanged
FRC < closing capacity which results into air trapping and leads to increased shunt (key gap)
What’s the % of O2 consumption used for work of breathing in adults?
1-2%
What’s the maximum FiO2 can Nasal cannula delivers?
0.45%
The best sign of preoxygenation is …
EtO2 > 0.9
Endo-bronchial intubation and effect hypoxia caused by?
When decrease in PaO2 and rise in PaCO2 starts to show up, what is the % of shunting?
Decrease in PaO2 (which later picked up by SaO2 when PaO2 falls below 100 mmHg)
Right to left shunting caused by unventilated lung.
PaO2 won’t change unless the shunting fraction > 50% (liner decrease in PaO2 with increased shunting), and PaCO2 begins to rise when shunt > 50%
Increased PaCO2 and (PaCO2 - EtCO2 gradient) is a sign of ….
Dead space
Where in shunting, the PaCO2 rises up when the shunting fraction > 50%
What’s the primary cause of v/q mismatch in laparoscopic surgery?
Physiological dead space (increased) due to abdominal destination and trendelenburg position, controlled mechanical ventilation and decreased CO.
Reason for v/q mismatch in mechanical ventilation?
Increased Dead space ventilation of non-dependent lung zone
PEEP decreases VR -> decreases CO -> decreases….
MAPs
Shift of ODC curve to left decreases/increases P50 and O2 affinity?
Left -> decreases P50 -> increases O2 affinity
Right shift is the opposite
Left shift of oxy- Hb dissociation curve causes?
MethHgb Carboxy Hgb Fetal Hgb Hypovothermia Decrease H+ Decrease in 2,3 DPG level
Right shift of oxy- Hb dissociation curve causes?
Sickle cell Thalassemia Pregnancy Acidosis Hyperthermia Increase in 2,3 DPG levels
Hypercarbia shift Oxy-Hg dissociation curve to …
Right
Increase O2 release to tissue
Both Carboxy Hgb and Methemoglobinemia causes no effect on PaO2 but both leads to hypoxia and one of the would show decreases O2 sat, which one?
Methemoglobinemia
Carboxy-Hgb would be normal pulse ox and it’s measured using co-oximeter to measure saturation
Drugs causing Methemoglobinemia?
Prilocaine Nitroglycerin Na nitroprusside Phenytoin Sulfonamides Metoclopramide
Most reliable sign of cyanide toxicity is…. and which is the early sign.
Metabolic acidosis more than elevated SvO2 (which is early sign)
Other ewarning is when having Tachyphylaxis for Na nitroprusside
Treatment for
Carboxy Hb
Methemoglobinemia
Cyanide toxicity
Carboxy Hb -> 100% O2 + hyperbaric
Methemoglobinemia -> Methylene blue, exchange transfusion, Hyperbaric
Cyanide toxicity-> Na Thiosulphate, Na nitrate, hydroxycoblamine, hyperbaric
CO posing symptoms by it blood level;
< 20
20-40
40-60
> 60
What’s the lethal carboxy-Hb blood level?
< 20 (headache, dizziness, confusion)
20-40 (N/V, disorientation, visual impairments)
40-60 (agitation, combativeness, coma, shock)
> 60 (death)
Why 100 O2 or hyperbaric O2 is used in CO poison?
It decreases the t1/2 of COHb
It increases dissolved O2 in blood.
What are indications for hyperbaric therapy in CO poisoning?
Hx of neuro impairments
Sx or evidence of cardiac abnormalities. (MI, arrhythmias)
COHb level > 25%
C/I to methylene blue ?
Cyanide poisoning
G6PD
SSRI use
ARF *** safe the kidneys
Indications for methylene blue
Methemoglobinemia
Vasoplegia
Indications for methylene blue are …
Methemoglobinemia
Vasoglegia
Hyperbaric O2 is useful in which poisoning …
CO
Cyanide
Methemoglobinemia
When ptn has smoked inhalational from confined airway fire, with clinical signs of airway injuries, ptn should be …
Intubated
A patient with acute asthma should be managed with ventilation that is ….
Slower RR.
Inadequate expiration time will lead to air trapping and increased intrathoracic pressure and hypotension
Condition. -> flow volume loop abnormalities
Variable extra thoracic —->
Variable intrathoracic—->
Fixed —->
Inspiration decrement
Epilators decrement
Both decrement
What type of anesthesia for following:
Post tonsillectomy bleeding ->
Large mediastinal mass compressing airway ->
Large laryngeal mass ->
IV RSI
Awake FOB or inhlational with spontaneous ventilation
Awake tracheostomy
The most common cause of desaturation one PACU is
Atelectasis
The most common cause of increased peak airway after positioning to trendelenburg is
Endobronchial intubation
Diagnostic modality of choice for anterior mediastinal mass is …
CT (not flow volume loops)
Complications should be aware with anterior medistinal mass are
SVC or PA obstruction
Manage by maintain preload, avoid factors increasing PA pressure, maintenance of spontaneous ventilation and have rigid bronchoscope in room with CPB standby.
Central sleep apnea may be predisposed by …
CHF, narcotic overdose and recent stroke
The slope of airway pressure waveform In VC mode is …. vs in PC mode ….
Decreases as more volume enters the lung, where the slope is constant across each breath in PC mode and the waveform appears flat
What are the setting can be changed in HFJV?
Airway pressures, RR, and I:E ratio
TV is not set
Settings can be changed in HFOV?
Frequency, amplitude, mean airway pressure, FiO2
TV is not in the setting of this mode ventilation
Describe the mechanism of gas exchange in laminar flow
Middle of small airway have laminar flow where margins of alveoli have opposite flow direction
Describe the mechanism of gas exchange in pendulluft ventilation
Movement of inspired gas from those alveoli that fill fastest to those fill slowly
Describe the mechanism of gas exchange in Taylor dispersion/connective streaming ventilation
Diffusion of high velocity central gases to the margins of airway. This helps gas mixing and exchange in smaller airway
What respiratory changes expected after lung transplant
- loss of cardinal cough reflex, distal to anastomosis
- loss of neurally mediated bronchomotor tone
- oxygenation is NORMAL
- Arterial hypercarbia expected in first month post transplant then normalizes
- ventilatory response to CO2 returns to normal beyond one month after transplant
What are the numbers indicates poor outcome after lung resection?
O2 use: VO2 max < 15 mL/kg/min
O2 removal: postop predictive FEV1 < 30%
O2 delivery: DLCO < 40%
Other: FEV1 < 2L, MVV < 50%, RV/TLC > 50%
Postop predictive FEV1 = FEV1 (1-% resected/100)
What inhibits HPV?
Hypocapnia
Inhalational agents
In left lateral decubitus during spontaneous ventilation, v & q are higher in the …
Dependent lung compared to non-dependent lungs
When sudden desaturation occur in OLV, first step …
Inform surgeon > 2 lung ventilation > confirm ETT position
If desaturation happens gradually then, add PEEP to dependent lung then CPAP to non dependent lung
What dose clamping of pulm artery by surgeon during OLV causes?
Clamping the pulm artery on operative side will eliminate the shunt and improve oxygenation
What’s the preferred mode of ventilation in patient with bronchopleural fistula?
HFJV
If not available then use OLV by DLT
Protective lung ventilation in ARDS is …
TV < 6 mL/kg and end inspirartory plateau pressure < 30 cm H2O
Acute exposure to high altitude causes
Hyperventilating (2/2 stimulation of peripheral chemoreceptors due to decrease in PaO2)
Resulting into respiratory alkalosis
What are the adaptation of chronic exposure to high altitude
- increased sensitivity to rise in PaCO2
- increase in HPV leading to increase PVR
- decreases PaO2, PaCO2 and HCO3
The ABG In pulm embolism shows
Hypoxemia and respiratory alkalosis
How dose prone position in ARDS decreases mortality?
Increases FRC, better drainage of secreations and improving oxygenation
What is it like the PFT in ascites
Restrictive pattern (decreased FEV1, FVC and normal FEV1/FVC)
All lung volumes and pulm compliance decreases
Negative pressure pulm edema causes by …
Inhalation or exhalation against obstruction
Etiology of atalectasis during perioperative period?
- decreases FRC, thoracic and pulm compliance
- increased absorption of alveolar gas in area of low V/Q areas
- decreases production of surfactant
Cough reflex mediated by …
Afferent: vagus
Efferent: vagus, phrenic, spinal motor nerves
cGMP mediated
Signs of correct DLT position on bronchoscope?
- Tracheal rings anteriorly
- RUL bronchus at 12 O’clock within a short distance from carina
- Trifurcation of RUL bronchus
- Bifurcation of LUL bronchus
What’s the maximum leak pressure of uncuffed ETT ?
20-30 cm of water
What’s the effect of positive pressure ventilation on heart, and kidneys
Decreases VR and CO
Decreases RBF, GFR, Na excretions and UO.
