Exam 3 Flashcards
(280 cards)
1
Q
What is ventilation?
A
ventilation is the process of exchanging gas (O2 and Co2) between the atmosphere and the lungs
2
Q
Ventilation 2 critical functions:
A
- O2 delivered to Hgb too support aerobic metabolism
- CO2 (primary end product of aerobic metabolism) eliminated from the blood.
3
Q
_____& _______contract during inspiration (tidal breathing)
A
diaphragm and external intercostals
4
Q
Is exhalation passive or active?
A
passiveW
5
Q
What is exhalation driven by?
A
recoil of the chest wall
6
Q
Accessory muscles for inspiration?
A
sternocleidomastoid and scalene muscles
7
Q
Accessory muscles for active expiration
A
internal intercostals (secondary)
TIRE
Transverse abdominis
Internal Oblique
Rectus abdominis
External oblique
8
Q
When does exhalation become an active process?
A
when minute ventilation increases or in patients with lung disease, such as COPD
9
Q
What vital capacity is required for an effective cough?
A
15ml/kg
A forced exhalation is required to cough and clear the airway of secretions
10
Q
Function of the conducting zone
A
bulk gas movement
-does not participate in gas exchange
it is anatomic dead space
11
Q
Where is the conducting zone?
A
begins at the nares and mouth and ends with terminal bronchioles
12
Q
What are the last structures perfused by the bronchial circulation?
A
terminal bronchioles
13
Q
What does the transitional zone contain?
A
respiratory bronchioles
14
Q
function of the transitional zone?
A
bulk gas movement
-respiratory bronchioles serve dual function of air conduit and gas exchange
15
Q
function of the respiratory zone?
A
gas exchange
16
Q
Where does the respiratory zone begin?
A
at the alveolar ducts and extends to the alveolar sacs
17
Q
gas exchange occurs across flat epithelium (type 1 pneumocytes) by _________.
A
diffusion
18
Q
What is transpulmonary pressure?
A
the difference between the pressure inside the airway and pressure outside the airway
TPP=alveolar pressure-intrapleural pressure
19
Q
What determines the rate of removal of carbon dioxide from the body?
A
alveolar ventilation
20
Q
When is TPP negative?
A
during forced expiration.
If it is negative the airway collapses.
21
Q
What is the amount of gas that is inhaled and exhaled during a breath?
A
tidal volume Vt
22
Q
normal TV
A
6-8ml/kg
23
Q
normal dead space
A
2ml/kg or 150ml
24
Q
When you exhale, which zone’s gas is removed first?
A
conducting zone gas removed first.
Any condition that increases the volume of the conducting zone (Vd) makes itmore difficult to eliminate expiratory gases from the lungs
25
Minute ventilation (Ve)
amount of air in a single breath multiplied by number of breaths per minute
26
What only measures the fraction of VE that is available for gas exchange and removes dead space from MV equation?
alveolar ventilation
27
Definition of anatomic dead space
air confined to conduction airways
ex. nose and mouth-->terminal bronchioles
28
definition alveolar dead space
alveoli that are ventilated but not perfused
ex. decreased pulmonary blood flow
29
physiologic dead space
anatomic Vd + alveolar Vd
variable
30
increased Vd-->airway
-facemask
-heat and moisture exchanger
-positive pressure ventilation
31
Which drugs increase Vd
-atropine because its bronchodilator action increases the volume of the conduction airway
anticholinergics
32
does old age increase or decrease Vd?
increase dead space
33
Which neck position increases dead space?
neck extension because it opens the hypopharynx and increases its volume
34
What neck position decreases dead space?
flexion
35
what pathophysiology increases dead space?
-decreased cardiac output
-COPD
-PE (thrombus, air, amniotic fluid)
36
Which position increases Vd?
sitting
37
Which position decreases Vd?
supine and trendelenberg (head down)
38
What can physiologic dead space be calculated with?
bohr equation
Vd/Vt= (paCO2-PeCO2)/PaCO2
compares partial pressure of CO2 in blood vs the partial pressure of CO2 in exhaled gas. The greater the difference between these values the greater amount of dead space
39
in the circle system, where does dead space begin?
at the y-piece
anything proximal to the y-piece does not influence dead space nor does increasing the length of the circuit.
Only exception to the rule is an incompetent valve in the circle system. In this situation the entire limb with the faulty valve becomes apparatus dead space.
40
What is the most common cause of increased Vd/Vt under general anesthesia?
reduction in cardiac output. If ETCO2 acutely decreases you should first rule out hypotension before considering other causes of increased dead space
41
Ventilation is ___L/min and perfusion is _____L/min
ventilation=4L/min
Perfusion=5L/min
42
What is the V/Q ratio assuming patient is standing
0.8
43
What is alveolar compliance?
change in alveolar volume for a given change in pressure
44
Where is ventilation poorest?
in the alveoli in the apex due to poorest compliance.
The slope of the curve is less steep in this region so there's a smaller volumetric change throughout the respiratory cycleW
45
Where is the ventilation the greatest?
the alveoli in the base due greatest compliance.
The slope of the curve is steeper in this region so there's a greater volumetric change throughout the respiratory cycle
46
What is the most common cause of hypoxemia in the PACU?
V/Q mismatch specifically atelectasis
47
The tendency of the alveolus to collapse is directly proportional to:
surface tension (more tension==more likely to collapse)
48
The tendency of the alveolus to collapse is inversely proportional to
-alveolar radius (smaller radius=more likely to collapse)
49
What does surfactant do?
equalizes the effet of surface tension by type 2 pneumocytes. This prevents alveolar collapse
50
When do type 2 pneumocytes begin producing surfactant?
22-26 weeks
51
When is peak production occur for surfactant?
35-36 weeks
52
zone 1
dead space
PA>Pa>Pv
53
zone 2
waterfall
Pa>PA>Pv
54
zone 3
shunt
Pa>Pv>PA
55
zone 4
pulmonary edema
Pa>Pis>Pv>PA
56
Normal A-a gradient
<15mmHg
57
Normal IRV
3,000 mL
58
IRV
volume of gas that can be forcibly inhaled after tidal inhalation
59
ERV normal
1,100 mL
60
ERV
Volume of gas that can be forcibly exhaled after tidal exhalation
61
Normal RV
1,200 ml
62
RV
volume of gas that remains in the lungs after complete exhalation
-the volume cannot be exhaled from the lungs
-this provides a "windbag" of alveolar gas that provides an oxygen reservoir during apnea
63
Total Lung capacity
IRV+TV + ERV +RV
64
Normal TLC
5,800mL
65
normal VC
4,500 ml
66
normal IC
3,500 ml
67
normal FRC
2,300ml
68
normal CC
variable
69
VC
IRV + TV + ERV
70
IC
IRV + TV
71
FRC
RV + ERV
72
What is Functional residual capacity?
The volume of air in the lungs at end-expiration
-the reservoir of oxygen that prevents hypoxemia during apnea
73
What is static equilibrium?
At FRC, the inward elastic recoil of the lungs is balanced by the outward elastic recoil of the chest wall
74
What effects do GA have on FRC?
decrease FRC
-diaphragm shifts cephalad 4cm due to decreased inspiratory muscle tone and increased expiratory muscle tone
75
What effects does obesity have on FRC?
decrease FRC
-decreased chest wall compliance
increased airway collapsibility
76
What effects does pregnancy have on FRC?
decreased FRC
-diaphragm shifts cephalad as a result of gravid uterus
-decreased chest wall complaince
77
What effects does a neonate have on FRC?
decreased FRC
less aveoli
decreased lung compliance
cartilaginous ribcage that is prone to collapse during inspiration
78
What effects does advanced age have on FRC?
increased FRC
decreased lung elasticity--> increased air trapping--> increased residual volume-->increased FRC
79
Which positions decrease FRC?
supine
lithotomy
t-burg
80
which positions increase FRC?
prone
sitting
lateral none or increased
81
What effects do NMB have on FRC?
decreased FRC
diaphragm shifts cephalad-->decreased lung volumes
82
What effects does light anesthesia have on FRC?
decreased FRC
straining-->forcefu expiration-->decreased lung volumes
83
What effects does excessive IVF have on FRC?
decreased FRC
fluid accumilation in dependent lung regions favor zone 3 development
84
What effects does high FiO2 have on FRC?
decreased FRC
-absorption atelectasis -->conversion of low v/q unit--?shunt unit
-newer evidence suggests FiO2< 80% at emergence PEEP or CPAP reduces atelectasis
85
What effects does COPD have on FRC?
increase FRC
airtrapping-->increased RV-->increased FRC
86
What effects does PEEP have on FRC?
increase FRC
recruits collapsed alveoli
partially overcomes effects of GA
87
What effects do sigh breaths have on FRC?
increased FRC
recruits collapsed alveoli
88
Factors that increased closing volume
CLOSE-P
COPD
LV failure
Obesity
Surgery
Extremes of Age
Pregnancy
89
At age 30, CC~FRC when
under general anesthesia
90
by age 44, CC ~FRC when
supine
91
by age 66, CC ~ FRC when
standing
92
a right shifted curve means what?
Hgb has a decreased affinity for oxygen. During normal physiology, this occurs at the metabolically active tissue
93
a left shifted curve means what?
hgb has increased affinity for oxygen. During normal physiology, this occurs in the lungs
94
What is the Bohr effect?
CO2 & hydrogen ions cause a conformational change in the hgb molecule; this facilitates the release of oxygen
-An increase in the partial pressure of CO2 and a decrease in pH cause Hgb to release oxygen
95
What is 2,3 DPG
produced during RBC glycolysis (Rapoport-Leubering Pathway)
-it maintains the curve in a slightly right shifted position at all times
96
What effect does hypoxia have on 2,3 DPG?
increased 2,3 DPG production. This facilitates O2 offloading
-2,3 DPG is an important compensation mechanism during chronic anemia
-
97
what happens to 2,3 DPG in banked blood
concentration fo 2,3 DPG falls. This shifts the curve to the left and reduces the amount of O2 available to the tissue load
98
Does Hgb F respond to 2,3 DPG?
no, which explains why Hgb F has a left shift (P50 =19 mmHg)
99
What is the primary substrate used for ATP synthesis?
Glucose
100
Glycolysis =net gain of how many ATP?
2
101
Kreb's cycle =net gain of how many ATP?
2
102
Oxidative phosphorylation =net gain of how many ATP?
34
103
In the absence of oxygen, pyruvic acid is converted to what?
ATP
104
What is the primary bi-product of aerobic metabolism?
carbon dioxide
105
3 primary ways CO2 is transported (buffered) in the blood?
1. as bicarbonate (70%)
2. bound to hemoglobin as carbamino compounds
3. Dissolved in plasma (7%)
106
What enzyme facilitates the formation of carbonic acid from H20 and CO2?
carbonic anyhydrase
107
Haldane effect
describes CO2 carriage.
It says that oxygen causes the erythrocyte to release CO2.
108
Hypercapnia is defined as
PaCO2 greater than 45mmHg
109
causes of Hypercapnia-increased CO2 production
-sepsis
-overfeeding
-MH
-intense shivering
-prolonged seizure activity
-thyroid storm
-burns
110
cause of hypercapnia-decreased CO2 elimination
-airway obstruction
-increased dead space
-increased Vd/Vt
-ARDS
-COPD
-repiratory center depression
-drug overdose
-inadequate NMB reversal
111
causes of hypercapnia-rebreathing
-exhausted soda lime
-incompetent unidirectional valve in the circle system
-inadequate fresh gas flow with mapleson circuit
112
pathophysiology of hypoxemia
increased alveolar CO2 displaces alveolar O2-->arterial hypoxemia
113
pathophysiology increased P50
oxyglobin curve shifts to the right releases more O@ to the to the tissues
-partially compensates for hypoxemia
114
increased PVR-patho of CO2
CO2 is a smooth muscle dilator except in the pulmonary vasculator
-CO2 increased PVR-increases workload in the right heart
115
How does hypercarbia affect blood pH
during respiratory acidosis, the kidneys excrete hydrogen and conserve bicarb to return pH to normal. This process begins within hours but may require several days for full compensation to occur
116
The carbon dioxide ventilatory response curve describes the relationship between pa CO2 and minute ventilation
117
What is the primary monitor of PaCO2?
central chemoreceptor in the medulla
118
What play a secondary role in monitoring PaCO2?
peripheral chemoreceptors in the carotid bodies and transverse and aortic arch
119
What is the apneic threshold?
highest PaCO2 at which a person will not breathe. Once the PaCO2 exceeds the apneic threshold the patient will begin to breathe.
120
Left shift in CO2 curve implies that apneic threshold has_______.
decreased
121
right shift in CO2 curve implies that apneic threshold has_______.
increased
122
causes of a left shift of the CO2 curve
-hypoxemia
-metabolic acidosis
-surgical stimulation
-CNS etiologies: increased ICP, fear, anxiety
Drugs:
-salicylates
-aminophylline
-doxapram
-norepinephrine
123
causes of right shift of CO2 curve
-metabolic Alkalosis
-carotid endarterectomy
-natural sleep
-drugs:
-volatile anesthetics
-opioids
-NMBs
124
Where is the respiratory center located in?
The reticular activating system in the medulla and pons
125
What is the primary job of the respiratory center?
Determine how fast and deep you breathe
126
What modifies the responses of the respiratory center?
cerebral cortex
127
location of the DRG?
medulla
nucleus tractus solitarus
128
function of the DRG
pacemaker for inspiration
primarily active during inspiration
129
location of the VRG?
medulla
-nucleus ambiguous
-nucleus retroambigus
130
function of the VRG
inspiration and expiration functions (primarily active during expiration
131
what contains the pre-Botzinger complex?
VRG
132
What group inhibits the DRG?
pneumotaxic center
133
function of the pneumotaxic center (upper pons)
triggers end inspiration by inhibiting DRG
-strong stimulus-->rapid shallow breathing
weak stimulus-->slow and deep breathing
134
pontine respiratory centers
pneumotaxuic and apneustic center
135
apneustic center -lower pons funciton
antagonized the pneumotaxic center which causes inspiration
-action is inhibited by pulmonary stretch receptors (J receptors)
136
Classic teaching says the DRG is considered the primary respiratory pacemaker. Newer evidence says that this function is performed by the :
-central pattern generator which includes the DRG, pre-Botzinger complex ( in the VRG) and other medullary structures
137
What do central chemoreceptors respond indirectly to
PaCO2 and this region sends stimulatory impulses to the dorsal respiratory center
138
What ions doesnt pass through the BBB
H+ & HCO3
139
Chief responsibility of the carotid monitor
for hypoxemia (PaO2< 60mmHg) they do not respond to SaO2 or CaO2
140
Why do we not do bilateral CEA simultaneously?
carotid endarterectomy severs the afferent limb of the hypoxic ventilatory response.
takes time for the body to recalibrate
141
sub-anesthetic doses of inhalation and intravenous anesthetics ____MAC depress the hypoxic ventilatory drive.
0.1
142
Hering breuer deflation reflex
when lung volume is too small, this reflex helps prevent atelectasis by stimulating the patient to take a deep breath
143
paradoxical reflex of the head
causes a newborn baby to take her first breath
144
What does J receptor stimulation cause?
tachypnea
The J receptors are activated by things that JAM traffic in the pulmonary vasculatture such as pulmonary embolism or CHF
145
Pulmonary C fiber receptors also called
J receptoras
146
What is a local reaction that occurs in response to a reduction in alveolar oxygen tension (not arterial PO2)
hypoxic pulmonary vasoconstriction
147
What does HPV minimize?
shunt flow during atelectasis or one0lung ventilation
148
What is the only region in the body that responds to hypoxia with vasoconstriction?
pumonary vascular bed
149
What factors inhibit HPV?
-volatile anesthetics >1.5 MAC reduce effectiveness of HPV
-vasodilators, PDEI, dobutamine, some CCB increase shunt flow by inhibiting HPV
150
What has the most significant contribution to airflow resistance?
radius of the airway
151
Which physiologic systems determine airway diameter?
PNS (vagus nerve)-->bronchoconstriction
mast cells and non-cholinergic PNS-->bronchoconstriction
non-cholinergic PNS (nitric oxide)-->bronchodilation
SNS (circulating catecholamines)-->bronchodilation
152
Are there SNS nerve endings in the airway smooth muscle?
no. Instead B2 receptors embedded in airway smooth muscle are activated by catecholamines in the systemic circulation
153
Beta 2 agonists MOA
B2 stimulation-->increased cAMP-->decreases iCa+2
-stabilizes mast cell membranes -->decreased mediator release
154
Side effects of B2 agonists
-tachycardia
-dysrhthmias
-hypokalemia
-hyperglycemia
-tremors
155
Beta-2 agonist drugs
-albuterol
-metaproterenol
-salmeterol
156
Anticholinergics MOA
M3 antagonist-->decreased IP3-->decreased iCa2+
157
anticholinergics used for bronchodilation
-atropine
-glycopyrrolate
-ipatropium
158
side effects of anticholinergics
-inhibits secretions
-dry mouth
-urinary retention
-blurred vision
-cough
-increased intraocular pressure with narrow angle glaucoma
159
corticosteroids moa
-stimulates intracellular steroid receptors
-regulates inflammatory protein synthesis
-decrease airway inflammation
-decreases airway hyperresponsiveness
160
side effects of corticosteroids
-dysphonia
-mypathy of larygneal muscles
-oropharyngeal candidiasis
-possible adrenal suppression
161
corticosteroid drugs
-beclomethasone
-budesonide
-flunisolide
-fluticasone
-tramcinolone
162
cromolyn moa
stabilizes mast cell membranes
163
leukotriene modifiers moa
inhibits 5-lipooxygenase enzyme
decreases leukotriene synthesis
164
leukotriene modifier drugs
-zileuton
-monteleukast
-pranlukast
-zafirlukast
165
theophylline moa
inhibits phosphodiesterase-->increases cAMP
increases endogenous catecholamine release
inhibits adenosine receptors
166
theophylline se plasma concentration >20mcg/ml
-N/V/D
-headache
-disrupted sleep
167
theophylline se plasma concentration >30mcg/ml
-seizures
-dysrythmias
-CHF
168
normal FEV1
>80% predicted value
169
FVC male normal
4.8 L
170
FVC female normal
3.7L
171
FEV1/FVC normal
75-80% predicted value
172
MMEF normal
100+/- predicted value
173
MMV normal male
140-180L
174
MMV normal value female
80-120L
175
DLCO normal
17-25ml/min/mmHg
176
What is the volume of air that can be exhaled after maximal inhalation in 1 second?
FEV1
-depends on patient's effect
-declines with age, so predicted value takes age into account
177
Volume of air that can be exhales after a maximal inhalation
FVR
178
<___% of FEV1/FVC suggests obstructive disease
70
179
is FEV1/FVC normal or abnormal with restrictive disease?
normal
180
What value is useful in dx of obstructive vs. restrictive disease?
FEV1/FVC
181
What is the most sensitive indicator of small airway disease?
MMEF (mid maximal expiratory flow rate)
182
What is the best test of endurance?
MMV (maximal voluntary ventilation
183
What measures airflow in the middle of FEV ?
mmef
mid maximal expiratory flow
184
MMEF obstructive disease
reduced
185
MMEF in restrictive disease
normal
186
Maximum value of air that can be inhaled and exhaled over the course of 1 minute
MMV
-maximum voluntary ventilation
187
What is DLCO (diffusing capacity)
-volume of carbon monoxide that can transver the alveolocapillary membrane per a given alveolar partial pressure of carbon monoxide
-based on Fick's law of diffusion
188
In a flow-volume loop flow is zero at _______
the line that transverses the loop
189
In a flow-volume loop , flow occurs during_____
inspiration (it moves away from zero)
190
In a flow-volume loop , flow becomes zero at ____.
end inspiration
191
In a flow-volume loop , what is the width of the loop?
Vital capacity
192
Patient examples of independent risk factors for pulmonary complications
-age >60 years
-ASA >2
-CHF
-COPD
-cigarette smoking
193
procedure examples of independent risk factors for pulmonary complications
aortic> thoracic
upper abdominal ~neuro~peripheral vascular>emergency
general anesthesia
duration of anesthesia >/=2 hours
194
diagnostic testing examples of independent risk factors for pulmonary complications
albumin <3.5g/dL
195
What are the short term benefits of smoking cessation?
-carbon monoxide t1/2 =4-6 hours
-P50 returns to near normal in 12 hours
-short term cessation does not reduce pulmonary complications
196
what are the intermediate term benefits of smoking cessation?
-return of pulmonary function takes atelast 6 weeks
this includes:
-airway functin
-mucociliary clearance
-sputum production
-pulmonary immune function
-hepatic enzyme induction also subsides after 6 weeks
197
How can you reduce PPC (postop pulmonary complications) in preop?
-tx expiratory outflow obstruction with bronchodilators and corticosteroids
-tx active infection with abx (no indication for prophylaxis from pulmonary infection)
-instruct patient on pulmonary recruitment maneuvers
-tx RV failure
198
How can you reduce PPC (postop pulmonary complications) intraop?
-consider regional instead of general
-minimally invasive surgical approaches instead of open
-avoid procedures lasting >3 hours
199
How can you reduce PPC (postop pulmonary complications) postop?
utilize effective analgesia
-use pulmonary recruitment manuevers (incentive spirometer, deep breathing, pulmonary toilet, CPAP)
200
obstructive disease is characterized by
-small airway obstruction and increased resistance to expiratory flow
-the problem is getting air out
201
restrictive disease is characterized by
a proportionate reduction in all lung volumes along with poor compliance
-the problem is small lung volumes
202
asthma is defined by an
acute, reversible airway obstruction that is accompanied by chronic airway inflammation and bronchial hyperreactivity
203
What is the greatest risk factor for developing asthma?
atopy
The condition of being "hyper-allergic"
204
s/s of asthma
wheezing
-dspnea
-chest discomfort or tightness
-production or non-productive cough
-prolonged expiratory phase
-eonsinophilia
205
most common ABG finding in asthma
respiratory alkalosis with hypocarbia
206
an elevated PACO2 on abg in asthma suggests:
-air trapping
-respiratory muscle fatigue and impending respiratory failure
207
in asthma, ekg may show
right ventricular strain and right axis deviation during a severe attack
-pulmonary vascular resistance increases the workload of the right heart
208
Are PFTs predictive of postop respiratory complications?
no, the exception is for lung reduction surgery
209
severe bronchospasm can cause
hypoxemia due to V/Q mismatch
210
what does CXR show with asthma
hyperinflated lungs with diaphragmatic flattening
211
Ventilator goals for asthmatic patients
-limit inspiratory time
-prolong expiratory time and tolerate moderate permissive hypercapnia
212
True/false: avoidance of tracheal intubation is a good idea if patient can safely receive regional or LMA
true
213
Which volatile anesthetics reduce airway resistance?
all VA dilate the airway and reduce airway resistance
sevo reduces risk of coughing and may reduce risk of bronchospasm
214
Which IV induction agent causes bronchodilation?
ketamine-only IV indiction drug that causes bronchodilation
215
What dose of lidocaine reduces airway reflexes at extubation?
1-1.5mg/kg before extubation suppresses airway reflexes
216
are anticholinesterases safe in a patient with asthma?
although they can precipitate bronchospasm coadministration of anticholinergics negates risk
217
How does intraop bronchospasm present?
-wheezing
-decreased breath sounds
-increased airway resistance
-increased PIP with normal plateau pressure
-increased alpha angle on capnogram (expiratory upsloping)
218
How is intraoperative bronchospasm treated?
-100% FiO2
-deepen anesthetic (volatile agent, propofol, lidocaine, ketamine)
-short-acting inhaled B2 agonist (albuterol)
-inhaled ipatropium
-epi 1mcg/kg IV
-hydrocortisone 2-4 mg/kg IV (does not tx acute symptoms but prevents problems later)
-aminophylline(theophylline doesn't work well for acute bronchospasm)
-helium-oxygen (heliox) reduces airway resistance
219
is montelukast used in the tx of acute bronchospasm?
no
220
COPD is characterized by
a reduction in maximal expiratory flow and a slower forced emptying of the lungs. Unlike asthma, the airflow obstruction is not fully reversible
221
Etiologies of COPD
-cigarette smoking
-respiratory infection
-exposure to dust with higher risk in the coal mining, gold mining, and textile industries
-alpha 1 antitrypsin deficiency
222
In COPD, chronically elevated PACO2 causes what?
respiratory acidosis. The kidneys reabsorb bicarbonate which provides a metabolic alkalosis
223
What happens to a patient with COPD who is administered supplemental O2?
it can ause oxygen induced hypercapnia
-it does not inhibit the hypoxic drive
224
Goal SPo2 Sat in COPD patients to minimize risk of oxygen-induced hypercapnia in a patient with severe cOPD
88-92%
225
Do not consider neuraxial anesthesia if the patient requires sensory blockade higher than__________.
T6
This impairs expiratory muscle function and reduces ERV. This hinders the patient's ability to cough and clear secretions
226
Which block causes paralysis of the ipsilateral hemidiaphragm so isn't the best block for a patient with severe COPD.
interscalene
227
For COPD patients which type of volatile agent is best?
low blood: gas solubility to minimize post op respiratory depression.
All halogenated anesthetics are bronchodilators (sevo and iso> des)
228
Volatile agents impair hypoxic pulmonary vasoconstriction >____MAC and increase shunt.
1.5
229
nitrous oxide is associated with
rupture of pulmonary blebs-->pneumothorax
230
How should you set the ventilator in a patient with COPD?
-use TV 6-8ml/kg IBW
-slow inspiratory flow helps has redistribute from high compliance areas to those with longer time constants. This maximizes matching of ventilation and perfusion throughout the entire lung.
-peep maintains airway patency in the alveoli at the flat portion of alveolar compliance curve.
increased expiratory time to minimize air trapping and auto peep
231
What can cause dynamic hyperinflation? (AUTO peep)
-if patient is unable to fully exhale with each breathe the portion of the previous breath remains in the lungs. If this occurs with subsequent breaths the effect is additive and airway pressure continues to rise.
-this is most evident by watching the waveforms baseline increase with each breath
232
Tx for dynamic hyperinflation
-risk can be reduced by emplying manuevers that prolong expiratory time (this allows patient to get the air out)
-options include decreasing the I:E ratio (such as 1:2 to 1:3)) reducing respiratory rate and reducing flow resistance
-for immediate tx you can disconnect the circuit you will hear whooshing sound as volume of air exits the lungs
233
Acute intrinsic restrictive lung disease examples
pulmonary edema
-upper airway obstruction
-aspiration
-reversal of opioid overdose
-cocaine overdose
-reexpansion of collapsed lung
-neurogenic
234
Chronic intrinsic restrictive lung disease examples.
-sarcoidosis
-drug induced pulmonary fibrosis
-amiodarone
235
How should you set the ventilator in restrictive lung disease?
-best ventilator strategy is to minimized risk of barotrauma
-best accomplished with smaller TV (6ml/kg IBW) and faster RR (14-18 breaths/min)
-keep peak inspiratory pressure below 30cmH20
-prolonged inspiratory time I:E 1:1
236
When does aspiration most commonly occur?
during anesthetic induction and intubation or within 5 minutes of extubation
237
What complications arise from aspiration?
1. gastric contents enter the airway-->risk of airway obstruction
2. gastric contents cause chemical burn to the airway and lung parenchyma-->risk of bronchospasm and impaired gas exchange
3. Infectious material enters the airway (bacterial infection)
238
Risk factors for aspiration
-trauma
-emergency sx
-pregnancy
-GI obstruction
-GERD
-peptic ulcer dz
-hiatal hernia
-ascites
-difficult airway management
-cricoid pressure
-impaired airway reflexes
-head injury
-seizures
-residual nBNM
239
s/s of aspiration
-most asymptomatic
-hypoxemia=hallmark
additional findings
-dyspnea
-tachypnea
-cyanosis
-tachycardia
-HTN
240
Initial tx for aspiration
1st head tilt down or to side
-upper airway suction to remove particulate matter
-lower airway suction is only useful for removing particulate matter. does not help chemical burn from gastric acid
-secure airway to support oxygenation
-peep to reduce shunt
-bronchodilators to reduce wheezing
-IV lidocaine to help reduce neutrophil response
-steroid probably wont help
-abx only indicated if patients develop a fever or increased WBC count >48 hours
241
How can you determine readiness for discharge if patient has aspirated
if they have not experienced any of the following within 2 hours of aspiration event:
-new cough or wheeze
-radiographic evidence of pulmonary injury
-SPO2 decrease >10% of preeop values on room air
-A-a gradient > 300mmHg
242
The best method to prevent ventilator associated pneumonia is _______
to avoid intubation altogether
if intubation unavoidable, the next best preventative measure is to minimize duration of mechanical ventilation
243
in pneumothorax POCUS will reveal
lack of lung sliding or absence of comet tails
244
emergency tx of tension pneumothorax includes____
insertion of a 14g angiocath into:
-2nd intercostal space at the mid-clavicular line or
-4th or 5th intercostal space at the axillary line
245
risk factors for pneumo
-central line insertion
-supraclavicular, interscalene and intercostal nerve blocks
-surgical procedures including radical neck dissection, shoulder arthroscopy, mastectomy, axillary lymph node dissection, mediastinoscopy, laparoscopy, nephrectomy
-chest trauma increased peak inspiratory pressure following chest trauma should raise suspicion
-barotrauma, higher or high inspiratory pressures
-lung cysts or bullae can explain and rupture when nitrous used
246
tx of flail chest
reducing pain with epidural catheter or intercostal nerve block
247
patient position risk of VAE highest to lowest
sitting>supine>prone>lateral
248
consequences of air trapped in pulmonary circulation from vneous air embolism include:
1. increased pulmonary artery pressure
2. increased RV stroke work index
3. RV failure
4. decreased pulmonary venous return
5. decreased LV preload
6. decreased CO
7. aasystole/CV collapse
249
S/s of VAE
-air observed on TEE
-mill wheel murmur on precordial doppler
-decreased ETCO2
-increased ETN2
-increased pumonary artery pressures
-hypotension
-dysrhthmias
-pulmonary edema
-hypoxia
-cyanosis
250
how to treat VAE
administer 100% FiO2
-flood surgical field with NS
-if surgical insufflation used, d/c gas insufflation and release pneumoperitoneum
-place patient left lateral decubitus position (durant's maneuver)
-Aspirate air from CVC
251
pulmonary ertery HTN is defined as mean PAP>
>25mmHg
252
pulmonary vascular resistance increases as a function of:
-increased vascular smooth muscle tone
-vascular cell proliferation
and/or pulmonary thrombi
253
normal PVR
150-250 dynesxsec x cm-5
254
things that increase PVR
-hypoxemia
-hypercarbia
-acidosis
-SNS stimulation
-pain
-hypothermia
-increased intrathoracic pressure
-mechanical ventilation
-PEEP
atelectasis
Drugs:
-nitrous oxide
-ketamine
-desflurane
255
things that decrease PVR
-increased PaO2
-hypocarbia
-alkalosis
-decreased intrathoracic pressure
-spontaneous ventilation
-preventing coughing/straining
drugs:
inhaled nitric oxide
-nitroglycerin
-phosphodiesterase inhibitors (sildenafil)
-prostaglandins PGE1 and PGI2
-calcium channel blockers
-ACE inhibitors
256
Carbon monoxide binds to the oxygen binding site on hgb with an affinity ___x that of oxygen. This displaces O2 from Hgb which reduces ____
200x
CaCO2
257
Does CO shift the curve?
left
258
T1/2 of carboxyhemoglobin
4-6 hours breathing room air
259
Does pulse ox measure COhgb?
no and may give falsely elevated result.
260
What is required to diagnose carboxyhemoglobinemia?
co-oximeter
261
What is the treatment for carboxyhemoglobinemia?
100% supplemental O2. Hyperbaric Oxygen therapy may be required
262
Hyperbaric o2 is indicated if COHgb exceeds _____.
25% or if patient is symptomatic
263
What drugs can you give down the ETT?
NAVEL
Narcan
Atropine
Vasopressin
Epinephrine
Lidocaine
264
Strong indications for mechanical ventilation-Vital Capacity
<15ml/kg
265
Strong indications for mechanical ventilation-inspiratory force
<25cm H20
266
Strong indications for mechanical ventilation-PaO2 at 21% FiO2
<55mmHg
267
Strong indications for mechanical ventilation-PaO2 at 100% FiO2
<200mmHg
268
Strong indications for mechanical ventilation-A-a gradient at 21% FIO2
>55mmHg
269
Strong indications for mechanical ventilation-A-a gradient at 100% FiO2>
>450mmHg
270
Strong indications for mechanical ventilation-PaCO2
>60
271
Strong indications for mechanical ventilation-respiratory rate
>40 or <6
272
What testing is indicated when preop assessment suggested an increased risk of postop pulmonary complications?
split lung V/Q function testing
273
normal VO2 max male
35-40 ml/kg/min
274
normal VO2 max female
27-31 ml/kg/min
275
best predictors of postoperative pulmonary complications for patients undergoing pulmonary surgery:
FEV1: <40% predicted
DLCO: <40% predicted
VO2 max < 15ml/kg/min
276
FRC can be measured indirectly by:
1. nitrogen washout
2. helium wash-in
3. body plethysmography
277
Vo2
3.5ml/kg/min
250ml/min (assuming 70 kg male)
278
Respiratory rate and pattern are determined by:
1. neural control in the respiratory center-medulla
2. chemical control in the central chemoreceptors-medulla
3. chemical control in the peripheral chemoreceptors carotid body and aortic arch
4. baroreceptors-lungs
279
Which surface of the medulla is the central chemoreceptor located?
ventral
280
What are the type 1 Glomus cells
sensors that transduce PaO2 into an action potential and mediate the hypoxic ventilatory drive
