1
Q
What are high risk results from PFT’s?
A
FEV1 < 2L
FEV1/FVC ratio < 0.5%
VC adults < 15cc/kg/ child <10cc/kg
VC < 40-50% of predicted value
2
Q
What are post operative extubation criteria?
A
- VSS, awake, alert, RR < 35
- On 40% FiO2, PaO2 > 70mmHg , PaCO2 < 55
- MIF MORE than -20 cmH2O
- VC > 15cc/kg
3
Q
MECHANICAL intubation criteria?
A
- RR > 35,
- VC <15cc/kg adult, VC , 10cc/kg child
- MIF LESS negative than -20 cmH2O
4
Q
OXYGENATION intubation criteria?
A
- 40% FiO2, PaO2 < 70mmHg
- A-a gradient > 350mmHg on 100% O2
5
Q
VENTILATION intubation criteria?
A
- PaCO2 > 55 ( except chronic hypercarbia/COPD)
- Vd/Vt > 0.6 ( 30% anatomical dead space)
6
Q
CLINICAL intubation criteria ?
A
- Airway burn
- Chemical Burn
- Epiglottis ( usually small children)
- Altered Mental Status
- Rapidly declining pulmonary function
- Fatigue ( common in elderly)
7
Q
What are your normal ABG values?
A
pH: 7.35 – 7.45 PCO2: 35 – 45 mmHg PO2: 75 – 105 mmHg Bicarbonate: 20 – 26 mmoles/L Base excess: -3 to +3 mmoles/L
8
Q
What does an increasing or decreasing CO2 by 10mmHg do to your pH?
A
Inversely decreases or increases by 0.08
9
Q
What is hypoxemia?
A
Decreased BLOOD PO2 < 75
10
Q
What is hypoxia?
A
A low O2 state.
11
Q
What is the A-a gradient?
A
Measures lung efficiency
12
Q
What is the equation for PAO2?
A
= (PB - PH2O) x (FiO2) - ( PaCO2/0.8)
13
Q
What is a roughly a normal A-a gradient?
A
Age/3
- Should be less than 20mmHg difference
14
Q
When is the A-a gradient widened?
A
V/Q mismatch Pneumothorax Shunt PE Diffusion Issues
15
Q
T/F: The A-a gradient normal with hypoventilation and low FiO2?
A
TRUE
16
Q
How do you manage an abnormal A-a gradient?
A
Treat underlying cause
- Supplemental O2
- Adjust ventilation
- add PEEP
- Treat atelectasis
17
Q
What equation is bicarbonate calculated from?
A
H= 24 x ( PaCO2/ HCO3)
18
Q
An increase or decrease in bicarb by 10mmoles does what to your pH?
A
A directly proportionate increase and decrease by 0.15
19
Q
What is the equation for TOTAL body bicarb deficit?
A
deficit = base deficit x weight in kg x 0.4 = in mEq/L
20
Q
How much total body bicarb deficit do you replace?
A
replace 1/2 the deficit
21
Q
Respiratory acidosis, an acute cause?
A
- Hypoventilation with Hypercarbia ( opioids)
- CNS depression – trauma, drugs
- Decreased FRC – obesity ( osa)
- Upper or lower airway obstruction
22
Q
Chronic cause of respiratory acidosis?
A
- COPD
- Emphysema
- Asthma
23
Q
How does the Body compensate for respiratory acidosis?
A
1-2 Days KIDNEYS compensate increasing H+ excretions and increase HCO3 being absorbed into the blood.
= increasing HCO3 value, and PARTIALLY restoring pH
24
Q
What are causes of respiratory alkalosis?
A
Hyperventilation with Hypocarbia
- -PRENANCY
- -Anxiety
- -Hypoxic respiration ( mountain climbing )
- Artificial ventilation
- -CNS disorders
- -Encephalitis
- -Narcotic Withdraw
- -Early septic shock
- -Hypermetabolic states
25
How does the body compensate for respiratory alkalosis?
Kidneys increase HCO3 excretion and retain H+ = partially correcting pH and resulting in a lower HCO3
26
What are causes of metabolic acidosis?
- Trauma ( hypoperfusion) = Lactic acidosis
- DKA
- ASA ingestion
- High protein intake
- Diarrhea ( losing HCO3)
27
How does the body compensate for metabolic acidosis?
-Respiratory ( central chemoreceptors) with HYPOCARBIA
- More rapid than renal compensation
-Eventual H+ excretion from the kidneys
= lowering CO2 and partially correcting pH
28
What are causes of metabolic alkalosis?
- Bicarb over infusion
| - Vomiting or excessive NG suction ( H+ loss)
29
Compensation for metabolic acidosis?
Respiratory compensation -->hyperventilate,
-However hypoventilation is limited due to eventual hypoxic drive
= increasing CO2 retention and partial correction in pH
30
T/F: Pulse oximetry is a mandatory intraoperative monitor?
True
31
Infrared light represents what? and is measured at what wavelength?
Oxyhemoglobin - 940nm
| Corresponds with 100% saturation
32
Red light represents what? and is measured at what wavelength?
Deoxygenated hemoglobin and 660 nm
| -Corresponds to 50% saturation
33
Hemoglobin variants
| Describe carboxyhemoglobin
From CO2 poisoning, is viewed as oxyhemoglobin by the pulse ox and shows up as 100%
-This is an overestimation of the true oxygenation, co oximeter used to distinguish between the two
34
What happens in Methemoglobin ?
Fe2 in Hb is oxidized to Fe3 and cannot transport O2, cyanosis seen when 15% of Hg is in methemoglobin form
**Absorbs equally at both wavelengths 1:1 shows an SpO2 of 85%
35
What causes Methemoglobin ?
- Nitrates
- Nitrites
- Nitroglycerine
- Nitroprusside
- Sulfonamides
- Benzocaine ( hurricane spray)
36
How do we treat Methemoglobin?
Low does methylene blue
| -Ascorbic acid
37
What two things do not affect the pulse oximetry?
Fetal Hemoglobin and bilirubin
38
Capnograhy: Rapidly and reliably indicates _____ intubation but does not reliably detect ______ intubation
Esophageal
| Endobronchial
39
What is the gold standard for tracheal intubation
End-tidal CO2
40
During surgery where a pt is in the lateral position, which long will be better ventilated? Is this a problem?
The nondependent lung will be better ventilated but the dependent lung will be better perfused causing a V/Q mismatch.
41
In the ____ and ____ position the dependent lung is better perfused (gravity) and ventilated
Awake & Lateral
42
Positive pressure ventilation favors the upper or lower lung and why?
The upper lung because it is more compliant.
43
T/F: The upper lung is favored.
True
44
T/F: Hypoxic pulmonary vasoconstriction improves a the right-to-left shunt.
True
45
Factors that inhibit hypoxic pulmonary vasoconstriction.
- Very high or very low pulmonary artery pressure
- Hypocapnia
- High or low mixed venous PO2
- Vasodilators (NTG, Nitroprusside, Beta-adrenergic agonist, calcium channel blockers)
- Pulmonary infections
- Inhalation agents.
46
During OLV what should your FiO2 be?
80-100%
47
Tidal Volumes should be kept at ______ during OLV.
10cc/kg
48
How do you ensure placement during OLV?
Fiberoptic scope
49
Add ___ of CPAP to nondependent lung and add ___ PEEP to dependent lung
5cm H2O for both
50
Malignant Hyperthermia is triggered by what?
Inhalation agents (not N2O), and/or succinylcholine.
51
Malignant Hyperthermia leads to an acute __________ state
Hypermetabolic
52
T/F: The ryanodine receptor (Ca release channel) fails in the sarcoplasmic reticulum leasing to decrease in Ca reuptake
True. This causes increase intracellular Ca leading to sustained muscle contraction, glycolysis, and heat production.
53
Malignant Hyperthermia has abnormal excitation-contraction coupling which results in what?
Prolonged and irreversible muscle contracture
54
What is the first most sensitive sign of MH?
Unexplained tachycardia
55
What is the most specific sign of MH?
Increase EtCO2- hypercapnia. Also decrease in SaO2 and SpO2.
56
What are the signs and symptoms of MH?
Muscle rigidity, dysrhythmias, tachypnea, cyanosis, sweating, unstable BP, mottling, trismus (masseter spasm), cola-colored urine, hyperthermia (least sensitive sign)
57
What would labs looks like in MH?
Metabolic Acidosis then a combined metabolic respiratory acidosis, hyperkalemia, hypercalcemia, hyperphosphatemia, creatinine kinase (CK) >1000 IU, myoglobinuria, hypoxemia
58
What is diffusion hypoxia?
This results from the dilution of alveolar O2 concentration by a large amount of N2O "outgasing" or leaving the pulmonary capillary blood at the conclusion of N2O administration.
59
How do you avoid diffusion hypoxia?
Administering 100% O2 following N2O use.
60
Factors that increase MAC
- *Age: term infant to 6 months of age has the highest MAC requirements
- Hyperthermia
- *Chronic EtOH abuse
- Hypernatremia
- Drugs that increase CNS catecholamine.
61
Factors that decrease MAC
- Hyperthermia
- IV anesthetics, opioids,
- Preop Meds
- Neonate/Premature infants
- Elderly
- *Pregnancy
- Acute EtOH ingestion
- Lithium
- Cardiopulmonary Bypass
- Hyponatremia
- Alpha 2 agonist (precede)
- Calcium Channel Blockers
- Severe Hypoxemia (PaO2 <38mmHg)
62
Factors that have no effect on MAC
- *Thyroid gland dysfunction
- Gender
- Hyper/Hypokalemia
- Hyper/hypocarbia
63
What is the second gas effect?
The ability of a large volume uptake of a first gas (N2O) to accelerate the rate of rises of the alveolar partial pressure of a concurrently administered companion gas (agent) thus speeding induction).
64
What is an example of the second gas effect?
Alveolar space: 70% N2O, 30% O2 and ISO 1% -> rapid uptake of 1/2 of the N2O -> 35% O2, and ISO now 1.53%
65
Nicotine stimulates sympathetic ganglia, which releases ________ from the ________ ________ and causes an increase in what?
Releases catecholamines from the adrenal medulla, increasing HR, BP, and SVR. This persists for 30 minutes after last cigarette.
66
25 pack per year increases physiologic age by how many years?
8 years
67
What is important for airway management in a smoker?
Pre-O2 well and avoid instrumentation of airway until deep level of anesthesia
68
You should advise patients to stop smoking how many hours prior to surgery?
12 hours. Will reduce COhb and nicotine levels to that if nonsmokers.
69
Cessation if greater than __ weeks will reduce post-op __________ _________.
- Greater than 8 weeks
| - Reduce Postop pulmonary complications
70
What is a normal I:E ratio?
1:2
71
What is the I:E ratio for someone with COPD?
1:3
72
T/F: In a patient with COPD, ETCO2 should be kept near the patient’s baseline, because a rapid correlation could cause metabolic alkalosis.
True
73
T/F: a COPD patient could laryngospasm due to secretions.
True. Section ETT frequently.
74
What medications do you want to avoid during a bronchospasm and why?
Histamine Releasing Drugs
- Pentothal
- Morphine
- Atracurium
- Mivacurium
- Neostigmine
75
Location of the larynx at birth vs an adult?
At Birth: level T C3-4
| Adult: anterior to 3rd-6th cervical vertebrae
76
What is a normal A-O extension?
35 degrees
77
What is a mallampati class 1?
Full view of uvula and tonsillar pillars, soft palate
78
What is a mallampati class 2?
Partial view of uvula or uvular base partial view of tonsils, soft palate
79
What is a mallampati class 3?
Soft palate only
80
What is a mallampati class 4?
Hard palate only
81
Airway innervation: where does the sphenopalatine ganglion innervate?
(Middle division of the CN V)- Nasal Mucosa, superior pharynx, uvula, tonsils
82
Airway innervation: what does the glossopharyngeal nerve innervate?
(CN IX) (lingual back 1/3, pharyngeal, tonsillar nerves) - Ora pharynx, supraglottic region
83
Airway innervation: what does the internal branch Superior Laryngeal Nerve innervate?
(CNX)- mucus membrane above the VC’s, glottis
84
Airway innervation: what does the recurrent laryngeal nerve innervate?
(CNX)- trachea below VCs
85
Stimulation of the internal SLN can cause what?
Laryngospasm
86
The external SLN provides what?
Motor innervation of cricothyroid muscle.
87
T/F: the RLN provides motor innervation to all larynx except cricothyroid muscle
True
88
Damage to the RLN causes the vocal cords to do what?
Adduction
89
Stimulation of the RLN causes the vocal cords to do what?
Abduction
90
What is the narrowest part of the airway in a child vs an adult?
Child: cricoid
Adult: vocal cords
91
How many C shaped cartilages make up the trachea?
20-25
92
What is the diameter and length of the trachea?
Diameter: 18-20mm
Length: 12.5-18cm
93
Where does the trachea extend to? Where does the carina extend to?
- Trachea: C6-T5
| - Carina at level T5-7
94
T/F: there is some gas exchange in the respiratory bronchiole?
True. **Review slide 12
95
What nerves transmits motor stimulation to the diaphragm?
Phrenic Nerves C3,4,5
96
Where are the intercostal nerves located that send signals to the external intercostal muscles?
T1-11
97
T/F: the act of inhaling is a positive-pressure ventilation
False: spontaneous respirations are negative pressure.
98
T/F: total lung capacity is the sum of all capacities and reserves, and can be measured with spirometry
False. It cannot be measured with spirometry.
99
What is FRC (functional residual capacity) the sum of?
Expiratory Reserve Volume and Residual Volume
100
How can FRC and TLC be determined?
1. Helium dilution
2. Nitrogen washout
3. Body plethysmography
101
Know the limbs of the flow-volume loop
Bottom inspiratory- semi circle shape
- Top limb Expiratory - pizza slice shape
- Slide 19
102
Be able to identify the following flow volume loops
- Fixed Obstruction
- Extra thoracic obstruction
- Intra thoracic obstruction
- Slide 20
103
Surfactant lowers surface tension of the alveoli and lunch by doing what?
- Increases compliance
| - Reduces work of breathing
104
How does surfactant behave to promote stability in the alveoli?
- 300 million tiny alveoli have tendency to collapse
- surfactant reduces forces causing atelectasis
- assists lung parenchyma "interdependent" support
105
Prevention of transudation of fluid into alveoli is accomplished by surfactant doing what?
- Reducing surface hydrostatic pressure effects
| - Prevents surface tension forces from drawing fluid into alveoli from capillary
106
Equation for Poiseuille's Law?
```
R= (8 x L x n) / ( Pie x r4)
R= resistance to flow in a tube
L= length of the tube
n= viscosity of the fluid
pie = 3.14
r = radius of the tube ( to the 4th power)
```
107
Reducing r ( the radius) by 16% will do what to R ( resistance)
DOUBLE
108
Reducing r ( radius) by 50% will do what to R ( resistance?
Increase 16 fold
109
Pulmonary Hemodynamics : pressures in each chamber of the heart
```
RA: 2-3
RV: 25/0
PA: 25/8 (mean 14)
Pulmonary capillaries 8-12
LA: 5-8
LV: 120/ 0
Systemic Arteries: 120/80
Systemic cap: 10-30
```
***Review slides 23 & 24
110
What are two mechanisms to decrease PVR that occurs when vascular pressures are raised?
- Recruitment
| - Distension
111
The pulmonary capillaries are an extensive network within the alveolar walls and cover what parent of the capillary surface?
70-80%
112
T/F: Total capillary surface area almost equals alveolar surface area?
True
113
Functional capillary volume, it increases by opening closed segments in what manner?
Recruitment
* *70 ml ( 1ml/kg body weight) normal volume at rest
* *200 ml at maximal anatomical volume
114
Alveolar gas exchange occurs over ___ seconds, and ___PCO2 diffuses out into the lungs and ___ PO2 diffuses into the lung capillary?
- 0.75 seconds
- 40mmHg
- 100 mmHg
*Diagram slide 27
115
What are the pressures of the alveoli, arteries, and venous capillaries in the different zones of the lung?
- Zone 1 : PA>Pa> Pv
- Zone 2: Pa>PA> Pv
- Zone 3 : Pa > Pv > PA - ideal
116
Where is the ventilation perfusion ratio most optimal in an awake sitting patient?
Dependent lung
| **Slide 29 graph
117
List factors that vasoconstrict increasing pulmonary vascular resistance?
* *Reduced PAO2
* *Increased PCO2
* *Histamine
- Thromboxane A2
- alpha- adrenergic catecholamines
- Angiotensin
- Prostaglandins
- Neuropeptides
- Leukotrienes
- Serotonin
- Endothelin
- Norepinephrine
118
Name vasodilators that decrease vasomotor tone
* *Increased PAO2
* *Nitric Oxide
- Prostacyclin
- B-adrenergic catecholamines
- Acetylcholine
- Bradykinin
- Dopamine
- Isoproterenol
119
T/F: Alveolar hypoxia inhibits hypoxic pulmonary vasoconstriction(HPV) ?
False
| - produces (HPV)
120
How does alveolar hypoxia cause vasoconstriction?
- Localized response of pulmonary arterioles
- Caused by hypoxia and enhanced by hypercapnia and acidosis
- Contraction of smooth muscle in small arterioles in hypoxic region
**Opposite reaction than systemic circulation
121
Why is HPV an important mechanism of balancing the V/Q ratio?
- **Shift of flow to better ventilated pulmonary regions
| - Results from decreased formation and release of Nitric Oxide by pulmonary endothelium in hypoxic region
122
Oxygen is continuously absorbed into blood from the alveoli breathed in from the atmosphere, what is the partial pressure controlled by?
Rate of absorption and ventilation
123
T/F: Normal alveolar PO2 is 100mmHg, the rate of ventilation and oxygen pressure will affect the alveolar PO2 during exercise?
True
- From 250ml O2/min to 1000ml/O2 min.
- alveolar ventilation (L/min)
124
T/F: CO2 is formed in the body and is discharged into alveoli and removed by ventilation, a normal alveolar PCO2 value of 50mmHg?
False
| -All correct , EXCEPT normal is 40 mmHg.
125
Alveolar PCO2 increase in proportion to CO2 excretion, the PCO2 value ____ in inverse to alveolar ventilation?
Decreases
126
What is normal CO2 production?
200mlCO2/min
*800 mlCO2/min
127
Expired air is a combination of what?
Dead space and alveolar air
| -Dead space exhaled first than second portion is a mixture of both
128
When is alveolar air expired?
End of exhalation
129
What is Fick's Law of diffusion equation?
Diffusion = (A x p-p x D) / T
D= diffusion of gas through a tissue membrane
A = cross sectional area of membrane
p-p: driving pressure ( pp difference )
D= gas coefficient
T= Tissue thickness or length through the membrane
130
Normal V/Q gas exchange pathway?
Pa: PVO2 = 40mmHg & PVCO2 = 46 mmHg
- Alveoli- CO2 goes in, O2 diffuses out into capillary
- Pulmonary vein:PaO2 = 100mmHg & PaCO2 = 40 mmHg
131
T/F: Physiologic Shunt is when the V/Q is above normal?
False
-Below normal
Shunt = perfusion but no ventilation
- Blood is being shunted from the pulmonary artery to pulmonary vein without participating in gas exchange
132
In a shunt, inadequate ventilation leads to what?
- A fraction of deoxygenated blood passing through the capillaries and not becoming oxygenated
- Physiologic shunt is total amount of shunted blood per minute
* *The greater the physiologic shunt the greater the amount of blood that FAILS to be oxygenated in the lungs
133
Where the V/Q ratio is greater than normal there is a larger amount of what?
DEADSPACE
| - ventilation to alveoli is good but blood flow is low (perfusion )
134
Physiologic dead space includes what two things?
Wasted ventilation
| Anatomical dead space
135
T/F: When physiologic dead space is great, much of the work of breathing is wasted effort b/c ventilated air does not reach the blood?
True
| Ex: PE
136
When your SaO2 sat reads 95,90, 75, what is your PaO2 respectively?
75
60
40
**Rough rule PaO2 40,50,60
SaO2: 70,80, 90
137
What is your Hb P50 point?
Sat 50
PaO2-27
- Point at which 50 percent of the hemoglobin are saturated with oxygen
-Slide 40
138
Understand the PO2 of the blood undergoing the venous admixture
Slide 41
139
The Hemoglobin's affinity for oxygen equilibrium curve is modified by a number of physiological or pathological factors , and affected in what two ways?
1- Shift in position
| 2- Change in shape
140
T/F: A change in shape indicates less of an interference with the O2 transport than the curve shift
False
| -Change in shape indicates a greater interference
141
What happens in a Right Hb-O2 shift?
-Hb has LESS affinity for O2, releases O2 to tissues, saturation will be less for a given PO2
142
What are the causes of a right shift in the Hb-O2 curve?
- increases CO2-cellular metabolism
- increase temp- increase metabolism and muscle
- increase H+ - acidosis, lactic acid production, BOHR effect
- increase 2,3 DPG - generated by glycolysis during anaerobic metabolism, bings to Hb and decreases affinity for O2
143
What happens in a L shift of the Hb- O2 curve?
Hb has HIGHER affinity for O2,
- binds O2 ( stays on the hgb molecule )
- saturation will be higher for a given PO2
144
How do you describe the O2 content in the blood-CaO2
The sun of O2 carried on Hb AND dissolved in plasma
145
What is the O2 blood content equation?
CaO2 = ( SO2 x [Hb] x 1.31 ) + ( PO2 x 0.003)
CaO2= O2 content in blood (ml/dL)
- SO2 = Hb Sat ( pulse ox or ABG) as a PERCENT
- [Hb]- Hb conc in gm/dL
- 1.31: O2 binding to Hb ( ml/gm)
- PO2 : arterial blood's pp of O2
- 0.003- Disolved O2 in blood
146
What is an example of the O2 content in blood?
Pt with sat. of 97%, Hb 15, and PO2 200: CaO2 = (0.97 * 15 * 1.31) + (200 * 0.003) CaO2 = (19) + (0.6) ml/dL
147
How do we calculate Oxygen delivery in the blood?
DO2 = CaO2 x CO
148
How is most CO2 transported the body?
BICARBONATE ( HCO3)
- 70%
- Hgb x CO2 = 23 %
- CO2 - 7 %
149
What accelerates the product of bicarb from H2O and CO2?
Carbonic anhydrase
150
What does the dorsal respiratory group ( DRG)control?
Inspiration and respiratory rhythm
151
Where is the DRG anatomically?
Extends most of the length of the medulla with most of the DRG neurons contained in the nucleus of the tracts solitarius
152
What nerves deliver sensory information to the DRG?
Vagal (X)
Glossopharyngeal ( IX)
-Also receives peripheral sensory signals for aid in control of respiration
153
DRG receives signal from what 3 sources?
1-Peripheral chemoreceptors
2- Baroreceptors
3- Lung receptors
154
Chemo-sensitive area of brainstem is a highly sensitive area on the -___medulla = ____chemoreceptors?
Ventral
| Central
155
Chemo-sensitive area responds to changes in what?
-Blood PCO2 or H+ ion concentration
**Also stimulates other portions of the respiratory center
156
Effects of blood CO2-
| T/F: respiratory center activity is increases very strongly by elevations in blood CO2 levels?
True
157
CO2 has a potent direct affect via what ion on what area of the brain?
- H+
| - Chemo-sensitive
158
***Is CO2 highly permeable to the BBB?
YES- hence by blood and brain concentrations are equal
159
CO2 reacts with H20 to form what?
Carbonic acid
| - Which dissociates into hydrogen & bicarbonate ions in interstitial fluid of medulla or CSF
160
The released Hydrogen ions in the brain do what?
Stimulate respiratory center activity
161
Blood PCO2 & pH effect alveolar ventilation
| PCO2 changes cause what?
Rapidly cause changes in RATE of pulmonary ventilation
162
A drastic increase in ventilation caused by _____ in PCO2
Increase
163
Ventilation is greatly increased with blood PCO2 above what level?
35mmHg
- Steep part of curve
* *slide 50
164
The size of the effect on respiration by a decrease in pH?
Smaller increase
| *Change in respiration is 10 times less with blood pH range between 7.3 - 7.5
165
Where are the peripheral chemoreceptors located?
```
Carotid Body
- bifurcation
-afferent nerve fibers pass via CN IX ( glossopharyngeal) to act on DRG
Aortic Body:
-Aortic arch
-CN X ( Vagus ) DRG
```
166
Stimulation of peripheral chemoreceptors is cased by what?
Decrease in arterial O2 content
167
Impulse rate is sensitive to drops in PaO2 from what range?
30mmHg to 60 mmHg ( hypoxia)
**This range is when the hemoglobin- oxygen saturation decreases rapidly
GNURS627-Resp
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