Advanced Mechanical VentilationList indications, contraindications, and advantages of HFNC and PRVC.List the variable that may be controlled on a HFNC system.List the components of a HFNC.Given patient data, recommend interventions with HFNC, APRV, VS, and APRV.Identify the approximate amount of CPAP generated by a HFNC system.List settings differences between PRVC and PC-CMV.Identify maximum PIP based on pressure setting in PRVC.List the increment range for PIP changes in PRVC.Identify the primary difference between PRVC and VS.Identify settings that may be changed in APRV to adjust oxygenation and ventilation.Describe the possible method(s) for determining the initial setting of Phigh in APRV.Describe the basic function of NAVA.Interpret the acid-base balance of ABG values.Identify the method by which intrapleural pressure is estimated in NAVA.Clinical Lab StudiesDefine:HematocritCytologyHistologyCulture and sensitivityUnifocal PVCMultifocal PVCList normal values and ranges of:RBCs (erythrocytes)WBCs (leukocytes)ThrombocytesReticulocytesGlucoseIdentify the lab test(s) that are used to measure liver function.Identify the lab test(s) that are used to measure kidney function.Identify the lab test(s) that are used to measure pancreatic function.Identify the electrolyte that results in diaphragmatic weakness if that electrolyte’s value is too low.ECG InterpretationIdentify the normal pacemaker of the heart.Identify the electrical event that follows the following ECG waves:P waveQRS complexT waveIdentify the variables measures by the vertical and horizontal axes of an ECG tracing.Identify the feature that all sinus rhythms share.Identify the following ECG rhythms when seen on an ECG tracingNormal sinus rhythmSinus tachycardiaSinus bradycardia1st degree heart block2nd degree heart block, Types I & II3rd degree heart blockAtrial fibrillationAtrial flutterVentricular tachycardiaVentricular fibrillation (coarse and fine)AsystoleScores & IndicesIdentify the use of and normal range for the following clinical scores. a. HACOR b. APGAR c. ROX d. Mallampati e. Ballard f. SOFA g. APACHE h. Apnea Test i. RSBI j. GCS k. AHI l. P/F ratioNoninvasive MonitoringIdentify the place on an ETCO2 graph where the highest PETCO2 exists.Describe the feature that make a monitoring route noninvasive.Describe the effect of an increased COHb would have on SpO2.Identify the process for minimizing the risk of skin burns when using transcutaneous gas monitoring.Identify acceptable anatomic locations for SpO2 monitoring sensors.Identify the patient population on whom the heel is an acceptable location for SpO2 monitoring.Ventilator GraphicsUsing ventilators graphics (scalars and loops), identify the following abnormalities.OverdistensionAir trappingCircuit leakThe presence of airway secretions
New Ventilator Modes
RCP 3009, Patient Monitoring w/Lab
Pressure Regulated Volume Control
(PRVC)
? PCV with volume guarantee
? Same settings as pressure ventilation
? Plus a target volume
? Flow waveform?
? Used with CMV and SIMV
PRVC Scalars
PRVC Vent Settings
? Mode
? Frequency
? Target volume
? FiO2
? PEEP
? Upper pressure limit
? Inspiratory time / Flow
? Rise time
? Alarms
PRVC
?
Ventilator gives test breath
?
Ventilator changes PIP per test breath result
?
Incremental changes of 1-3 cm H2O
?
If breath is 5 cm H2O of P limit, ALARM
?
Average of VT used, not breath-by-breath
PRVC
Ventilator does not allow PIP to rise higher
than 5 cm H2O below set upper pressure
limit
? Example: If upper pressure limit is set to 35
cm H2O and the ventilator requires more
than 30 cm H2O to deliver a targeted VT of
500 mL, an alarm will sound alerting the
clinician that too much pressure is being
required to deliver set volume (may be due
to changes of CL and/or RAW)
?
PRVC
?
Indications
? Patient who require the lowest possible
pressure and a guaranteed consistent VT
? ALI/ARDS
? Patients requiring high and/or variable I
? Patient with the possibility of CL or Raw
changes
PRVC Advantages
Maintains a minimum PIP
? Guaranteed VT and VE
? Reduces WOB
? Allows patient control of RR and VE
? Variable flow to meet patient demand
? Decelerating flow: improved gas distribution
? Breath-by-breath analysis (not changes)
?
PRVC Disadvantages and Risks
?
Varying mean airway pressure
?
May cause or worsen auto-PEEP
?
Sudden increase in RR and demand may result
in a decrease in PIP and ventilatory support
?
Awake, non-sedated patients may not tolerate
it, especially with low VT
Volume Support
Spontaneous mode (no mandatory breaths)
? Similar to PSV, but with VT target
?
? Changes PIP in increments of from 1 to 3 cm
H2O
? 5 cm H2O below high PIP: Alarm
PIP self-adjusts to reach target VT
? All breaths : Patient-triggered, pressurelimited, and flow-cycled.
? Automatic weaning of pressure support
?
? Ventilator gives minimum PIP to achieve target
VT
VS Settings
? Target volume
? FiO2
? PEEP
? Upper pressure limit
? Inspiratory time / Flow
? Rise time
? Alarms
? Apnea (Apnea mode is PRVC.)
VS Scalars
? Same as PRVC, but with spontaneous
breaths only
VS
? Little data to show it actually works.
? If pressure support level increases to
maintain VT in a patient with increased RAW,
auto-PEEP may increase.
? If target VT set too high, weaning may be
delayed.
VS Indications
?
Spontaneous breathing patient requiring
minimal support
?
Patients with inspiratory effort but need
adaptive support
?
Patients asynchronous with the ventilator
?
Ready to wean
VS Advantages
Guaranteed VT and VE
? Pressure supported breaths using the
lowest required PIP
? Decreases the patient’s spontaneous RR
? Decreases WOB
? Allows patient control of I:E ratio
? Breath-by-breath analysis
? Variable flow to meet the patient’s
demand
?
VS Disadvantages
?
Spontaneous efforts required
?
Varying mean airway pressure
?
Auto-PEEP may affect proper functioning
?
Sudden increase in RR and demand may
result in a decrease in ventilatory
support
APRV
? APRV is classified as a time-triggered, pressure-limited,
time-cycled (partial) mode of ventilation, which allows
for unrestricted, spontaneous breathing throughout the
entire ventilatory cycle. CPAP at two levels, for
different, time limits, with most time at the upper
pressure level.
APRV (AKA)
? BiVent – Servo
? BiLevel – Covidien
? DuoPAP – Hamilton
? BiPhasic – Carefusion
P High
? Upper pressure level
? Patients can breathe spontaneously at this
level at any time
? Too high a P high may overdistend the lung
? P high is related to MAP and affects oxygenation
? As lung is recruited, VT will increase
T high
? Time at P high
? Shorter T high causes more releases
?
?
?
?
Increases releases (more T low events)
Most CO2 is eliminated during release.
The more releases, more CO2 is removed
Converse is true (fewer releases, less CO2
removed)
? Spontaneous breaths between the releases
? At T high
P low (PEEP)
? PEEP
? Often set to zero
? Intrinsic PEEP
? Pressure difference between P high and P
low is directly related to size of release
? Increase P low decrease size of release
? Decrease in size of release affects CO2
T low (T PEEP)
? Time at P low
? Normally set from 0.5 to 1.0 sec.
? Changes in T low will affect intrinsic PEEP.
? T low is inversely proportional to intrinsic PEEP
? Measuring Total PEEP: average pressure in lung at
end expiration. Measured with expiatory hold.
? Enough Total PEEP to avoid derecruitment,
? Too much may cause overdistention and
hemodynamic compromise.
BiVent
? Set—P high, T high, P low (PEEP), T low (T PEEP)
Basics
? Essentially
? T High ~ TI
? T PEEP ~ TE
? Releases ~ f
? T High + T PEEP = TCT
APRV Advantages
Similar to IRV, with spontaneous breathing
Facilitation of spontaneous breathing
Increased patient comfort vs. conventional
ventilation
? Decreased sedation
? Elimination of paralytics
? Improved hemodynamic performance
? Decreased PIP for any given MAP
? Increased recruitment, and limited derecruitment
?
?
?
APRV Guidelines: Initial Setup
? P high:
Set to previous Pplat, if
less than 35 cm H20
(If no previous mode, set at 30 cmH20)
? T high:
Set to 4.5 to 5.5 seconds
? P low (PEEP):
Set to zero cm H2O
? T low (T PEEP):
Set to 1 s, or to keep
expiratory flow to 25%-75% of
PEFR
APRV Adjustment
? Oxygenation: FiO2 or P high
? Hypoxemia: Increase FiO2 or P high
? Hyperoxemia: Decrease FiO2 or P high
? Ventilation: T high
? Hypocapnia: Increase T high
? Hypercapnia: Decrease T high
Neurally Adjusted Ventilatory Assist
(NAVA)
? Controls ventilator output by measuring the
neural impulse to the diaphragm
? Phrenic nerve innervates diaphragm
? Carries impulse from brain
? Chemically paralyzed patients have nerve
impulse
? Electrodes on esophageal tube sense impulse
in phrenic nerve (Edi)
? Flexible response to effort
? Improves synchrony and weaning
Nasogastric/Orogastric Tube
? Strength of nerve impulse is directly
proportional to size of breath
? Bigger impulse = bigger breath
? Sensors on tube
? Pick up impulse
? 9 sensors
? Placement via
ventilator
Neuro-Ventilatory Coupling
Time Lag in Ventilator Triggering
Central Nervous System
?
Phrenic Nerve
?
Diaphragm Excitation
?
Diaphragm Contraction
?
Chest Wall and Lung
Expansion
?
Airway Pressure, Flow and
Volume
Ideal
Technology
New
Technology
Current
Technology
Ventilator
Unit
Edi Measurement
NAVA
High Frequency Oscillation
Ventilation (HFOV)
How Does HFOV Work
? Keeps lungs open and keeps alveoli at
constant (low) pressure
? Ventilates very fast with very small
breaths
? May reduce the risk of further lung
injury
? May be not started early enough, in
some cases
Patients Who May Benefit
from HFOV
? ALI or ARDS
– Failing lung protection
? FiO2 ?0.50, PEEP ?10 cm H2O, and P/F
ratio 30 cm H2O
? CXR consistent with ARDS
Airway Pressure in the
Lung
Upper AW
Middle AW
Lower AW
and Alveoli
Comparison of CMV and HFOV
HFOV Objectives
? Improve oxygenation
? CO2 removal
? Reduce Ventilator-Induced Lung
Injury (VILI)
–Controlled pressure in airway
? Ventilator will
push air in
(active
inhalation) and
pull air out
(active
exhalation)
? Breathe in down
center of lumen
? Breathe out
around outside
of lumen
Flow with HFOV
Ventilator Settings
Settings
Alarms
? Frequency (Hertz)
? High Pressure
? Amplitude (?P)
? Low Pressure
? Bias Flow
? % Inspiratory Time
? FiO2
? These are typically
about 5 cm H2O
above and below
set MAP
Explanation of Settings
? Hertz (Hz) number of cycles per
minute
– 1 Hertz is equal to 60 cycles
– Or roughly: 1 Hz – 60 bpm
? Amplitude or change in pressure (?P)
– Associated with VT
? MAP
? Bias Flow is continuous flow
– Flow during inhalation and exhalation
Sample HFOV Initial Settings
? FiO2 = 1.0 or current FiO2 + 10%
? Hz
= 5 – 6 (300 to 360 bpm)
? Power setting = 4 and look for
chest wiggle factor (CWF)
? PAW = MAP on conventional
ventilator + 5 cm H2O
? Inspiratory Time % = 33%
? Bias Flow = 25 – 40 L/min
Management of CO2
? Hz (rate)
? Amplitude (VT)
? Cuff leak
Hertz
? Number of cycles per minute (like RR)
– There is a big difference
? Difference is due to active exhalation
– HFOV piston pulls air out of lungs
? CO2 level relates directly with Hz
– Hz goes up then CO2 will go up
– Hz goes down then CO2 will go down
? The lower the Hz, the more air is moved (bigger VT)
? The higher the Hz, the lesser air is moved (smaller
V T)
Hertz
? Lowering the Hz makes the stroke volume bigger.
? A bigger stoke volume makes the VT larger and
removes more CO2
Amplitude
? Amplitude or ?P is just like PCV
? Higher amplitude, larger VT
– Lower CO2
? Lower amplitude, smaller VT
– Higher CO2
? Amplitude controls
chest wiggle factor
(CWF)
Chest Wiggle Factor (CWF)
? Increase amplitude until you see
– Mid-thigh wiggle
? The ?P will cause vibration or ripple
? Travels from chest down the body
? Ripple should stop at mid-thigh
? Good starting point for power setting
CWF
Hz and Amplitude Together
? The stroke volume will increase if:
– Amplitude changes (directly changes VT)
– Hz changes (inversely changes of VT)
Bias Flow and Cuff Leak
? Increase bias flow
– Increases MAP
? Decrease bias flow
– Decreases MAP
? Increase cuff leak
– Decreases MAP
? Decrease cuff leak
– Increases MAP
Other Tools for CO2
? TI % is typically set at 33%
? For high CO2
– TI may be increased
? Not used much (only small change in CO2)
? May use if first 3 not working
– Bias flow may be decreased; 40 L/min may increase PaCO2
CO2 Removal Controls
Power /
Ampitude
Hertz
(Frequency)
.
Amplitude
? Amplitude is created by the
piston movement
? Piston is controlled by the
POWER setting
? Causes Chest Wiggle
Factor.
? Peak to trough pressure swing
around MAP
Hertz
.
Putting Hz and Power Together
Items That May Lessen CO2
Removal
? Bias Flow >40 L/min
? Secretions
? Bronchospasm
? Soft Mattress
? CXR white out
Controls for Oxygenation
? MAP and oxygenation are directly
related
? Bias Flow
–Increase bias flow, MAP increases
–Decrease bias flow, MAP decreases
? FiO2
MAP and Oxygenation
Alveolar Inflation Comparison
Carney, CCM 2005
HFOV Controls / Knobs
Monitoring
Ventilation
PaCO2
Oxygenation
PaO2
FiO2 on Blender
CMV vs HFOV
CMV
HFOV
MAP
HFOV and APRV
Weaning
? Wean FiO2 for SpO2 >90%
? When FiO2 is 0.40, wean MAP by 2-3
cm H2O every 4-6 hours
? Criteria for transition to CMV
– FiO2