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http://www.drugbank.ca/drugs/DB01001
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MOA of all drugs
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A-aDo2: A-a gradient,
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norm 5-10 mmHg on .21, 30-60 on 100%,
>350mech support, <350 weaning.
Represents potential to Oxygenate vs. the
amount of O2 in the artery. Every 50mmHg is
approx. 2 percent shunt above norm of 2-5%
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Increased A-a= SHUNT
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a/A ratio: PaO2/PAO2 norm is 90%,
>35%weaning, reflects efficiency of
oxygenation as a percentage, <74% shunt,
V/Q mismatch or diffusion defect
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Anion Gap= the difference in the measured
cations and the measured anions in serum,
plasma, or urine.
Used to assess Metabolic Acidosis or
alkalosis, normal around 8-16 mEq/L. Use
MUDPILES to determine cause of metabolic
acidosis (high gap)
= ( [Na+] ) − ( [Cl−]+[HCO3−] ) without
potassium
= ( [Na+]+[K+] ) − ( [Cl−]+[HCO3−] ) with
potassium
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CaO2: norm 20 vol%
(Hbx1.34)SaO2 + (PaO2x.003) total amount
of O2 carried in 100ml of blood, combined
content of O2 carried on Hb and dissolved in
plasma,
(can be reduced by <Hb, anemia or <CO)
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CvO2: (Hb x 1.34)SvO2 + (PvO2 x .003)
norm is 15 vol%, represents the value of O2 in
blood returning to the right side of the heart
after tissues have oxygenated.
C(a-v)O2 = arterial to mixed venous oxygen
content difference
Determines how well the tissues take up O2
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VO2: O2 consumption,
norm is 250mL/O2/L/min,
[C(a-v)O2 x QT] x 10, the amount of O2
consumed by the body per liter of blood per
minute.
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Ct: Tube compliance aka compressible
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Ex: Vt 550 – (25 x3) = 475
volume, volume lost to pt circuit, approx
3ml/cmH20 x PIP, deduct from VT to find
actual delivered tidal volume. VT-(PIP x 3)
equals actual VT.
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Time Constant: The given % of a passively
exhaled breath of air will require a constant
amount of time to exhale
Depends on the resistance and compliance of
the lung
TC= R x C (in liters)
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TC: Time constant, (Raw x CS)e,
where e represents volume exhaled as a
percent,
1 is 63%,
2 is 86%,
3 is 95%
5 is 100% exhaled.
TC <3 leads to air trapping.
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DO2: O2 Delivery, (CaO2 x CO) x 10, norm is
1000mL/O2/min
The ability of oxygen to tissues based on
cardiac output and Hb
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I-time = Inspiratory Time,
E-time = Expiratory time,
TCT= total cycle time (I +E)
I-time when compared to E-time will always be a 1:
something ratio.
Respiratory rate = 60 /TCT
EXAMPLE: Calculate I:E ratio, rate and TCT if I-time is 1.2
seconds and E-time is 3 seconds.
TCT = 1.2+ 3 = 4.2
Rate = 60/4.2 =14
I:E = TE/TI = 3/1.2 = 2.5, (I:E is 1:2.5)
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I-time = Inspiratory Time,
E-time = Expiratory time,
TCT= total cycle time (I +E)
I-time when compared to E-time will always be a
1: something ratio.
Respiratory rate = 60 /TCT
Example: The ventilator is set at 12 breaths per
minute with an IE ratio of 1:3. How many seconds
for inspiratory time?
Seconds per breath = 60 divided by 12 = 5
seconds
TI=5/(1+3) =5/4=1.25 seconds
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Example: The ventilator is set at 12 breaths per
minute with an IE ratio of 1:3. How many seconds
for inspiratory time?
Seconds per breath = 60 divided by 12 = 5
seconds
TI=5/(1+3) =5/4=1.25 seconds
Since I/E = 1:3, the expiratory time = 1.25 • 3 =
3.75 seconds
Note: 1.25 + 3.75 = 5 seconds (the number of
seconds per breath in this case.) ( a breath equals
inspiration + expiration)
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Flow = VE x (I+E)
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Example: Calculate flow given:
VT 600
Rate 12
IT 1.5
ET 3
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600 x 12 = 7.2 L x (1.5 +3) = 32 L
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ETT size -2 x2
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8.0 ETT
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(8-2)2 = 12 French
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Mean Airway pressure (Paw): ½ (PIP-peep)
(TI/TCT) + PEEP
Average amount of pressure throughout the
TCT
AKA: Pmean, MAP, MAWP, PAW
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VE = actual VE x actual PaCO2
desired PaCO2
New rate = Current rate x actual PaCO2
desired PaCO2
New Vt = Current Vt x actual PaCO2
desired PaCO2
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Example: Calculate the new set rate for a
patient,
Current set rate: 12
PaCO2 on ABG 48
Desired PaCO2=40
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New Rate = 12 x 48 / 40 = 14.4 (14)
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Example: calculate the new VT for a patient
with:
Current VT = 500
PaCO2 on ABG 55
PaCO2 desired 40
New Vt = 500 x 55 = 687.5 (688)
40
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Example: Calculate new VE for a patient with:
Current VE = 12
PaCO2 on ABG 60
Desired PaCO2 40
VE = 12 x 60 = 18
40
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Desired FIO2 = (desired PaO2)(known FIO2) /
known PaO2
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Ex: Calculate the desired FIO2 for a patient
with:
PaO2 on ABG 50
Current FIO2 30%
Desired PaO2 60
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60 x 0.30/ 50 = 36%
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Cardiac Output (CO) = amt of blood ejected
from the heart per minute
CO= Stroke Volume X heart rate
normal 4-8 L/min
QT = cardiac output
Cardiac Index (CI)= amount of blood pumps
per minute based on body weight CI=
CO/BSA, normal 2.4-4 L/min
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QS/QT: Pulmonary Shunt equation
(CcO2-CaO2)/(CcO2-CvO2)
Norm 2-3%,
>20% vent indication,
<20% weaning,
>30% is life threatening.
Measures % of QT not exposed to ventilation,
shunts caused by atelectasis, edema, pneumonia,
pneumothorax, obstructions
CcO2: Content of pulm capillary blood oxygen at
100% FIO2, (Hbx1.34)1 + (PAO2x.003) used in
shunt equation
Total Ve (given from vent) –(VT mech x f
mech)/ f spont (total rate – mech rate set)
SPONT VOLUME: 8.1 -5.6/10=250 ml
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Measured when machine in SIMV mode,
represents what the patient is actually
breathing on his/her own.
GOAL is 5-7 ml/kg, adjust PSV to achieve this
EX: Pt on SIMV 8, total rate is 12, Set VT 500,
Ve 8.0
8 –(4) /4 = 1000 ml
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VE total: (VT mech x f Mech) + (VT Spont x f
spont)
Calculated when patient is in SIMV mode
Example:
VT mech 700 ml, f mech 8, VT spont 250 ml, f
spont 10
Total Ve –(VT mech x f mech)/ f spont
SPONT VOLUME: 8.1 -5.6/10=250 ml
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VC: Vital capacity, 65-75 mL/kg, <10mL/kg
indicates support, 10-15 mL/kgweaning
Maximum inhalation followed by a maximum
exhalation
Measured by a Wright Respirometer
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RSBI: Rapid shallow breathing index,
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RR/VT, <105 weaning
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must be calculated during spont breathing,
press support reduces predictive value
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MIP/NIF: Max Inspiratory Press, norm -80 - -
100, > -20 support indicated, <-20 weaning
(remember that negative numbers are larger
as they become less, -25 < -20)
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PAP: pulmonary artery pressure, norm 25/10
(20-35/5-15), >35/15 is inconsistent with
weaning, pulm hypertension, left vent fail,
fluid overload
PCWP: pulmonary artery wedge pressure,
norm 5-10 mmHg, >18 is inconsistent with
weaning, left vent failure, fluid overload
CVP: central venous pressure, norm 2-6
mmHg, 2-6 weaning
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Plateau pressure: The amount of pressure
held in the lung during a brief inspiratory
pause. This is used to calculate static
compliance. The higher this number the
worse the patients compliance as it
represents distending pressure. Typically less
than PIP, but more than MAP.
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Maximum pressure reached during a positive
pressure inspiration
Keep lower than 40 cmH2O
Increased with:
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Secretions
Bronchospasm
Decreasing Compliance
Increased RAW
Asynchrony/fighting vent