Transcript Trouble shooting-Case scenarios

Ventilator Review
Indications
• Prophylactically (neuromuscular, impending
failure, pre-op, post op)
• Airway protection (sedated, stroke, trauma,
drug OD)
• Ventilatory failure (pH less than 7.25, CO2>50)
• Shunts/oxygenation failure
Impending Ventilatory Failure
• Pt maintains marginally acceptable blood gas
values at the expense of significant increased
WOB.
• Progressive acidosis and hypoventilation
ensue.
Severe Hypoxemia
• Pa02 < 60 mm Hg on Fi02 of 50% or greater.
Prophylactic Ventilatory Support
• Risk of pulmonary complications
• Reduce hypoxia of major body organs
• Reduce cardiopulmonary stress
Initial Settings
• Generic startup:
– AC or SIMV modes
– PC, VC or PRVC
– FIO2 40-60%
– Rate 8-12
– VT 6-8 ml/kg or PC 15-25 cmH2O
– Flow 40-60L, I-time 0.8-1.25
– Sensitivity 1-3 flow or pressure
– PEEP 0-5
– Rise time 50%, 0.2-0.4 seconds
Combinations
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AC-PC
AC-VC
AC-PRVC
SIMV-VC (PS, TC, VS)
SIMV-PC (PS, TC, VS)
SIMV-PRVC (PS, TC, VS)
Spontaneous (PS, TC,
VS, PAV)
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APRV
HFOV
HFPV
HFJV
Settings/Monitored Data
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PEEP
FIO2
I-time
Flow
Sensitivity
Rate
Mode
Breath Type
VT
Pressure limit
Rise time
Pressure Support
Volume Support
Tubing Compensation
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MAP
PIP
Total rate
Minute Ventilation
Plateau pressure
Dynamic/static
compliance
• WOB, Time constant
• Spontaneous/mech
Volume
Initial Setup
• Acute air trapping (Asthma/COPD
exacerbation) Restrictive disease (ARDS, PN,
Pulmonary fibrosis)
– AC or SIMV
– VC with lower VT 3-5 ml/kg with rate 15-25 OR PC
15-25 with rate 15-25 OR PRVC low VT range
– FIO2 depending on previous ABG/FIO2 setting
– IT 0.7-0.9, Flow 60L, achieve appropriate I:E ratio
Initial Setup
• If you have a ABG prior to startup, adapt initial
settings per blood gas and prior device
• Ex: if patient has extreme respiratory/met
acidosis: hyperventilate patient if patient was
actively breathing prior to being on vent, if
patient apneic, then use normal vent settings
• Use PEEP for patients with shunts, pulmonary
edema
• Suggest sedation for initial ventilator
stabilization (Versed, Ativan, Deprivan,
Fentanyl, Morphine, Precedex…)
Alarms
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High PIP: 10-15 above (observed pressure)
Low PIP: 5 below (observed pressure)
High rate: 10-15 above total rate
Ve: 2-3 L above/below
VT: 200-100 above/below
Apnea alarms 20 seconds
ALWAYS READJUST ALARMS PER PT CHANGES
OR VENT CHANGES
MODES
• AC, SIMV, CPAP/Spontaneous
• AC all breaths are mechanical, patient can
trigger a breath only, but machine will
complete the breath for the patient
• SIMV both mechanical and spontaneous
breaths, must calculate spontaneous VT,
support Spont breath with PSV, VS or TC
• CPAP all breaths are spontaneous
Settings Review
• Trigger: What begins inspiration, either time, flow
or pressure; or via NAVA. The time applies to non
patient triggered breaths. Control trigger by
setting sensitivity
• Set sensitivity 1-3. If the sensitivity is set >3 may
lead to difficulty triggering breath on and induce
WOB, if set to low may cause auto-triggering
• Set in all modes (including CPAP, PSV still needs a
trigger!)
• Assess triggering by looking at pressure-time
graph or pressure-volume loop
Work to Trigger
30
Adjust sensitivity per patients ability, missed
triggers will lead to asynchrony
Paw
cmH2O
Sec
1
-10
2
3
4
5
6
Assisted Breath
VT
Clockwise to Counterclockwise
LITERS
0.6
Expiration
0.4
Assisted Breath
0.2
Inspiration
Paw
cmH2O -60
40
20
0
20
40
60
Settings Review
• Cycle: This is what cycles the breath off. Either
flow, pressure or volume. Pressure and
volume limits are the most common
• Volume: Set appropriate per patients size. If
patient has restrictive lungs or is air trapping
severely, use 3-5 ml/kg range otherwise 6-8
• Set in VC and PRVC. Too much volume can
cause volutrauma/barotrauma
• Assess with Volume-time or Pressure-volume
graphic
Setting Review
• Volume control used to set a consistent
minute ventilation.
• In VC you set the VT, flow and flow pattern.
The pressure and I-time are variable
• On PRVC the volume is only targeted not
guaranteed, will fluctuate with changing
breathing patterns. You set target VT, I-time,
pressure limit and rise time.
PV loop
• Note over
distention
• Patient triggers
• Asynchrony
• RAW
Pressure-Volume Loop Changes
The pressure-volume loop
changes, flattening out and
moving to the right. What could
cause this to happen?
VT
LITERS
0.6
0.4
0.2
Paw
cmH2O
-60
-40
-20
0
20
40
60
Changes in Compliances
Did anybody say decrease in
compliance? The difference
between the white arrow and the
red arrow represents a change in
compliance as indicated by an
increase in pressure without a
corresponding increase in tidal
volume.
Paw
cmH2O
-60
40
20
VT
LITERS
Indicates a drop in compliance
(higher pressure for the same
volume)
0.6
0.4
0.2
0
20
40
60
Setting Review
• Pressure Limit: Set 15-25, increase to increase
VT, decrease to lower VT
• Set in PRVC and Pressure control but…
• All breath types have pressure limits set in the
alarms, in the alarm setting, the high pressure
alarm becomes the pop-off, patient will not be
able to exceed this level. This is why it is
important to set alarms appropiately.
Flow Acceleration Percent
AKA: Rise Time
Minimal Pressure Overshoot
P
Slow rise
Moderate rise
Fast rise
.
V
Pressure Relief
Time
Pressure time graph
• Used to assess patient triggering
• Used to assess inadequate flow rate/double
breaths
• Assess level of PEEP
• Assess rise time
• Assess Plat time
Setting Review
• Generally Pressure control is used for patients
with restrictive disease, but can be used with
any patient
• Helps with patients asynchrony because
patient dictates their own flow pattern.
• In PC, you set Pressure limit, I-time and rise
time. Volume and flow are variable
• Pressure limited, time cycled
Ventilator Review
• MODES:
• AC: start with this mode if patient is apneic or if
patient’s spontaneous breaths are inadequate or
erratic. Patient can trigger breaths but machine
will complete the breath at preset limits
• SIMV: May start with this mode on any patient
who is apneic if you suspect he/she will regain
spontaneous breathing. Otherwise, use only if
spontaneous breaths are adequate. Must set a
PSV in this mode or VS or TC
Ventilator Review
• CPAP/Spontaneous: May start for Type I
failure, patient must have ability to breathe
spontaneously without much need for
ventilatory support. Must have a PSV or ATC or
VS
• PRVC: duel mode, set in either AC or SIMV
mode. Set pressure limit, target VT…Does not
work well with erratic breathing patterns
PSV
• PSV only applies to spontaneous inspiratory
breaths, used to augment spontaneous VT, set
to achieve spontaneous VT of 5-7ml/KG, set
above measured RAW
• Start with a PSV of about 6-10, titrate or
increase as needed. PSV max = 20-25
• Pressure limited, patient cycled, set sensitivity
and rise time, e-sens
Pressure Support Ventilation - PSV
• Applies a preset pressure plateau to the
patient’s airway for the duration of
spontaneous breathing.
• Used only in ventilator modes that allow for
spontaneous breathing
Pressure Support Ventilation - PSV
• Patient has control over
– Tidal Volume
– Inspiratory Time
– RR
– What is the cycling mechanism for Pressure
supported breaths?
Ventilator Review
• APRV: for restrictive lungs only, spontaneously
breathing
• HFOV: for restrictive lungs only,
sedate/paralyze.
• ASV: used as a single mode, from start to
finish, not for ARDS or neurological breathing
patterns
Ventilator Review
• Flow: Set only in Volume control. When set use
either constant or decelerating patterns.
Increased flow= decreased I-time. Give patients
with COPD increased flows to meet demands and
give long E-time. Increase when you increase VT,
or change flow pattern
• I-time: Set in PRVC, PCV. Increase or decrease to
achieve appropriate I:E, increased
rates=decreased I-time. Inverse used for
restrictive diseases to increase oxygenation
Setting Flow
• The easiest rule of thumb to follow is that a
patient requires a peak flow roughly four
times that of the minute ventilation (if the MV
is 15 liters, the patient requires a PF of >60
liters). However if the patient is breathing
spontaneously, then bedside adjustment is
required to ensure that flow matches patient
efforts. The peak flow should be set slightly
higher if a decelerating waveform pattern is
being used, and, in particular, those with
airflow obstruction
A higher expiratory flow rate and a decreased expiratory time
denote a lower expiratory resistance. A decrease in expiratory
resistance may also be observed after the patient receives a
bronchodilator (e.g. MDI or aerosolized neb tx). Monitoring the
duration
of the therapy’s effect can help determine the indicated
120
frequency of therapy.
.
SEC
V
LPM
120
1
2
3
4
5
6
Flow Patterns
• Constant/Square:
– Causes lower I-time, less MAP, higher PIP
– Only set in VC
– Can increase oxygenation
– Generally uncomfortable for your patients
Flow Patterns
• Ramp
– Can be set in volume, automatic pattern in PC
– Will increase MAP, and prolong I-time
– When switching from constant to ramp, you may
have to increase flow to maintain same I-time, I:E
ratio
Pressure time graph
• Used to assess patient triggering
• Used to assess inadequate flow rate/double
breaths
• Assess level of PEEP
• Assess rise time
• Assess Plat time
Flow vs.Time Curve
120
Constant Flow
Descending Ramp
INSP
Inspiration
.
V
LPM
120
SEC
1
2
3
4
5
6
EXH
Flow-Time Curve
120
INSP
.
Insp. Pause
V
LPM
SEC
1
2
3
4
5
6
Expiration
120
EXH
Patient / Ventilator Synchrony
Volume Ventilation Delivering a Preset Flow and Volume
30
Adequate Flow
Paw
Sec
cmH2O
1
-20
2
3
4
5
6
Patient / Ventilator Synchrony
The Patient Is Out breathing the Set Flow
30
Air Starvation
Paw
Sec
cmH2O
1
-20
2
3
4
5
6
What we see here is a patient’s inspiratory flow demand greater
than the peak flow set on the ventilator, which can lead to
patient/ventilator dysynchrony. What are we going to do to
amend this situation?
What options do we have?
Humidification
• The gas delivered to patient during mechanical ventilation
should be filtered, humidified, and heated
• Heated humidifier (requires heated circuit, delivers 100% RH)
or HME
• HME only supplies about 50% humidity
• Contraindicated with
– Dehydration
– Thick secretions
– Hypoventilation
– Prolonged use >72 hours
– Patients who are hyperventilating
PEEP
• Increases the baseline airway pressure.
• Optimal PEEP:
– Increase PaO2 (above 60 at minimum not over
100, with least amount of hemodynamic effects)
– Assess intrinsic PEEP with flow-time and
expiratory pause
• Two major indications
– Shunt and refractory hypoxemia
– Decreased FRC and lung compliance
• Atelectasis, pulmonary edema, air trapping
Complications of PEEP
• Decrease venous return (decreases CO, decreases
blood to kidney, GI tract, liver…) Causes ADH release
and fluid accumulation
• Barotrauma
• Increased ICP
• Alterations in renal function and H20 balance
• Alterations in liver function.
• ASSESS hemodynamics (CVP, PAP, PCWP, Blood
Pressure/MAP, urine output, lab values…)
Effects on Intrapleural Pressure
PEEP increases intrapleural pressure
The extent of the increase is determined by:
1. The amount of PEEP applied
2 The stiffness of the individual’s lung
Effects on Intrapleural Pressure
The > the pulmonary compliance, the > the
transmission of PEEP to the intrapleural space
and the greater the increase in intrapleural
pressure.
Effects on FRC
Regardless of the condition of the lung at the
time of application, PEEP increases FRC
FRC is increased by these primary
mechanisms:
1. Lungs are elastic. Any increase in end
expiratory pressure increases over all
lung volume.
Effects on FRC
FRC is increased by these primary
mechanisms:
The diameter of conducting airway can increase 1
to 2 mm as PEEP is applied.
In pts with a decrease FRC as a result of alveolar
collapse caused by surfactant instability, PEEP
maintains alveoli inflated after they are recruited
by the peak airway pressure.
Effect on Pulmonary Compliance
Because PEEP increases FRC, it alters
pulmonary compliance.
Effect on Pulmonary Compliance
Monitoring of effective static compliance can
be used to help to determine the “optimal” or
most appropriate PEEP level
- Best compliance
changes in VT will change the PEEP
considered optimal
Vt should always be constant during
PEEP titration
Effect of PEEP on Deadspace
 Because PEEP increases FRC by
distending alveoli, deadspace
is usually increased in:
- Patients with normal lungs
- Patients with COPD
- Pts with non-homogeneously
distributed disease process
Effect of PEEP on Deadspace
Because stabilization of recruited alveoli,
appropriated PEEP levels usually decrease
deadspace in pts with ALI/ARDS
Some have proposed monitoring deadspace or
changes in CO2 at a constant VE as an
indication of appropriate PEEP level
Effect of PEEP on the Cardiovascular
System
Is a reduction in CO as a result of increased
impedance to venous return by an increased
in intrathoracic pressure
This increase in pressure decreases end
diastolic volume and stroke volume of both
ventricles
Higher levels of PEEP markedly increase right
ventricular afterload, increasing end-diastolic
volume and decreasing ejection fraction
Effect of PEEP on the Cardiovascular
System
This reduces left ventricular distensibility
This results in a decrease in left ventricular
end-diastolic volume and stroke volume
Effect of PEEP Therapy on PaO2
Because PEEP therapy causes a minor increase
in the partial pressure of oxygen in the lung, a
small increase in PaO2 may be noted even in
the healthy lung.
In patients with ALI/ARDS, PaO2 levels also
demonstrated only a small increase as the
PEEP level is increased and will not markedly
increase until PEEP is sufficient to avoid derecruitment of recruited alveoli has been set.
Effect of PEEP Therapy on PaO2
 When appropriate PEEP
is set, PaO2 values may
increase significantly.
 PEEP
cm H20
0
5
10
12
15
PaO2
mmHg
45
48
53
56
110
Effect on Intrapulmonary Shunt
Increasing PEEP levels result in a decrease in
intrapulmonary shunt.
As recruited alveoli are maintained open with
PEEP, ventilation/perfusion matching improves
and shunting decreases.
Intrapulmonary shunt may continue to
decrease even when CO is significantly
decreased.
Indication For PEEP Therapy
ALI/ARDS
- Atelectasis and consolidation
- Decrease lung compliance
- Decrease FRC
- Refractory hypoxemia
- Increased intrapulmonary shunting
- Altered surfactant function
Indication For PEEP Therapy
Secondary Indications
- Acute cardiogenic pulmonary edema
- Chest Trauma
- Apnea of prematurity
- Obstructive Sleep Apnea
- COPD
- Asthma
Ventilator Induced Lung Injury (VILI)
The application of mechanical Ventilation can
cause lung injury:
- Oxygen toxicity
- Barotrauma
- Volume trauma
- Atelectrauma
- Biotrauma
Oxygen Toxicity
High inhaled oxygen concentration results in
the formation of oxygen free radicals.
Radicals cause ultra changes in the lung
similar to acute lung injury.
Animals - 100% O2 causes death in 48-72
hours.
Healthy humans - 100% O2 develop
inflammatory changes in 24 hours.
Ideally the FIO2 should be < 60%.
Barotrauma
Is the most acute and immediate severe form
of ventilator induced lung injury.
Is literally air within a body space or
compartment.
It is a result of disruption of the alveolar
capillary membrane that allows air to dissect
along facial planes and accumulate within the
pleural space or some other compartment.
Potential Complications of MV
• Ventilator malfunction
– Manually ventilate patient
• Cardiovascular compromise
– Monitor vital signs
– Support cardiac output: volume replacement,
inotropes
• Barotrauma
– Alveolar rupture due to overdistention
– Monitor PIP, breath sounds
Potential Complications of MV
• Infection
– ET tube bypasses natural airway defense
mechanisms
• Nosocomial pneumonia, aspiration pneumonia
– Good hand washing, provide mouth and tube care
• Psychological
– Patients may be extremely anxious and/or agitated
– Give consistent, calming explanations, offer
reassurance
– Sedation, anti-anxiety agents frequently indicated
I:E Ratio
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•
•
•
The ratio of inspiratory to expiratory time.
Kept 1:2 to 1:4
Inverse ratios uncommon
Increase E-time with COPD, increase E-time to
correct air-trapping
• Calculate I:E ratios
– I-time, TCT, E-time
I:E Ratio
• Longer I times used to increase mean airway
pressure and improve oxygenation.
• Longer E times used on pts to reduce the
possibility of air trapping and auto peep.
Factors Effecting I:E Ratio
• Flow rate
• Tidal Volume
• RR
• Peak Flow
• Flow Pattern
• Inspiratory Time
I:E ratios
• When you make changes to rate of tidal
volume/or pressure limit, you may have to
adjust flow or I-time to maintain I:E ratio
• Auto-peep from inadequate exhalation can
lead to patient ventilator asynchrony
Selection of FiO2
• Goal: To achieve clinically acceptable PaO2
between 60 - 100 mmHg.
• If PaO2 is within desired range before vent
support, use same FiO2 when ventilation is
started.
• For emergencies: Start at 100% FiO2.
– CHF/Pulmonary Edema
– CO poisoning
– Smoke Inhalation/Burns
• All others 40-60%
Selection of FiO2
• If baseline ABG is not available, select an
initial high FiO2 (40-60%) to benefit patients
with presumed severe hypoxemia.
• If starting at 100% FiO2, reduce this as quickly
as possible. Continuous use is not
recommended:
– Reabsorption (or resorption) atelectasis
– Oxygen toxicity
Selection of FiO2
• FiO2 can be adjusted after ventilation has
started based initially on an SpO2 of > 92%
(PaO2  60 mmHg).
• If > than 50% - 60% is needed due to
intrapulmonary shunting, add PEEP.
Manipulation
• Non-compensated Respiratory Acidosis:
• You need to increase Ve. On AC mode this is done
by:
– Increasing VT (8-12 range), watch PIP’s
– Increasing PIP, watch total PIP
– Increasing rate, unless patient is breathing over BUR
– increase Ve target if on MMV or ASV modes
– Remove any unnecessary mechanical deadspace
On SIMV mode: you can increase rate even if patient is
over BUR, or increase VT/PIP or increase PSV to
increase Spontaneous VTe
Ventilator Review
• On HFOV: To decrease PaCO2
– Increase AMP, then decrease Hz, Induce leak
around ETT cuff.
– To increase PaCO2 do the opposite
– To improve PaO2, increase FIO2 and MAP
• On APRV:
– To decrease PaCO2 Increase HP or Increase LT or
decrease low Pressure
Ventilator Review
• Uncompensated Respiratory Alkalosis
• On ACV mode:
– Decrease rate first if patient is not breathing over
BUR.
– Decrease VT or PIP
On SIMV decrease Rate, VT/PIP or PSV OR
change to CPAP mode
Ventilator Review
• Vent Check:
– Check ventilator orders, check for new orders and
assure old orders. Weaning orders? Pertinent
procedures that would require transport or
procedures that would require your presence like a
bronch?
– Assess patients chart first know patients Hx and why
they are on the ventilator
– CXR, CT scan and all other pertinent diagnostic tests
– ABG, CBC, other pertinent labs
– Sedation
– Hemodynamics, BP, arrthymias and cardiac status
Ventilator Review
• Vent Check
– Note if patient is in isolation
– Assess patient’s vital signs
– Check BS, HR, Spo2, cardiac rhythm, BP and
hemodynamics
– Assess capnography if applicable
– Note presence of Foley and its contents, chest tubes,
NG tubes, PICC lines, IV’s, A-lines…
– Note medications hanging in room
– Note patients ETT tape or holder, does it need to be
changed
Ventilator Review
• Vent Check
– Note ETT size and location at lip.
– Note patient and their sensorium
– Perform MLT/MOV or check cuff pressure directly
– Ensure tubing is free from condensation, if patient
is on a heater, drain circuit into water trap, ensure
heater water is filled. If HME, ensure it is not
occluded, if it is, change it
– Note inline suction ballard, if heavily soiled,
change it
Ventilator Review
• Vent Check
– Check patients settings, mode, VT/Pip, rate, rise time,
sensitivity…also alarm settings and apnea settings
– Assess ventilator graphics, note presence of over
distension, air leaks, auto-peep, secretions…
– Record monitored data including: PIP, VTE/VTI, Ve,
Rate, Static Compliance, Dynamic compliance, MAP,
total PEEP…
– Check suction pressure, suction patients lungs as
needed and also mouth with yonker
– Document all pertinent information
– If you do not document it wasn’t done!
Ventilator Review
• Vent Check
– Your first vent check should be the most time consuming.
– Any changes that are made, make sure the patients RN is
aware
– As a student you will not be making any changes without
approval from your preceptor
– Typically a brief summary is written regarding the patient.
Put any changes you made or ABG’s you drew here and
maybe the plan for the day
– Inline HHN or MDI’s should be given AFTER you have done
your check and suctioned patient (if it was needed)
Ventilator Review
• Vent Check
– The patient should have a resusitation bag at
bedside, plugged into oxygen. If the patient is on
PEEP, ensure there is a peep valve.
– The ventilator should be plugged into the red
outlet incase of power outage
– Note signs in room for Dialysis Shunts
– A spare trach should be in the room for trach
patients
Ventilator Review
• Transporting patients:
– The hospital will either make you attach the
patient to a transport ventilator or you will bag
the patient to their destination
– You may have to bring along the ventilator and
attach it once you reach the area you are
transporting to, in this case, simply select same
patient so that all the settings remain
– Have a full E-tank available. Assist in the pushing
of gurney and also the attachment of monitors
Troubleshooting
• If the ventilator is alarming and the immediate fix
is not apparent, you must take the patient off and
bag them until the problem can be solved
• For high pressure alarms: assess patient for
asynchrony, fighting ventilator, mucus, change in
compliance, increase RAW, bronchospasm, biting
tube…. Inform your preceptor if you can not
resolve the issue yourself. For example patient is
biting tube, inserting an oral airway, don’t do it
alone
Consider the following
• Secretions in airway
• Tube block
• Kinking of tube
• Biting the tube
• Water in the tube
• Cuff herniation
• Rt. bronchial intubation
• Fighting the ventilator
•Cough
•Increased airway
resistance
•Bronchospasm
•Decreased compliance
•Atelectasis
•Fluid overload
•Pneumothorax
Troubleshooting
• If the low pressure, or low Vte alarm is
sounding.
– Check for obvious leaks, if a leak if found plug it
– Check cuff pressure, if blown, let your preceptor
know, the ETT may have to be changed
– If patient self extubated, and it is plainly obvious
(tube is seen hanging from patients mouth), finish
the extubation, bag as needed and call for help
Troubleshooting
• 18 yr old man intubated for
organophosphorus poisoning and
intermediate syndrome was on the following
settings: AC 12, VT 550, FIO2 30%
• He suddenly desaturates. You notice that his
resp rate is 35/min, heart rate is 120/min, BP
is 90/70mmHg.
• Auscultation reveals equal vesicular breath
sounds. What would you do?
Troubleshooting
• A 35 yr old man with status epilepticus
following organochloride ingestion is being
ventilated in the ICU. You are called because
of desaturation and persistent low pressure
alarms. How would you tackle the situation?
Consider the following
•
•
•
•
•
•
•
Cuff leak.
Leak in the circuit
Loose connections
ET tube displacement
Disconnection
Inadequate flow
Low supply gas pressures
Low pressure alarm
• FiO2 to 100%
• Check all connections for leaks. Start from ventilator
inspiratory outlet—humidifier—inspiratory limb—
nebulizer—Y junction—dead space—et tube cuff—
expiratory limb—expiratory valve.
• If inspiratory effort excessive-inadequate flow—
increase inspiratory flow, decrease Ti, increase TV
• Check gas pressures
• If all normal and problem persists, change ventilator
High pressure alarm
•FiO2 to 100%
•Look at chest movement, auscultate air entry.
AUSCULTATION
UNEQUAL AIR ENTRY
•Collapse,
•tube malposition
•pneumothorax
DECREASED AIR
ENTRY BILATERALLY
Tube/tracheal block
WHEEZES
Bronchospasm
Ventilator Alarms
• Low Pressure
– Loss of circuit pressure
– Loss of system pressure
– Premature termination of inspiration
– Inappropriate ventilator settings
– Set 5 – 10 cm below peak pressure
Ventilator Alarms
• Low PEEP/CPAP
– Set at 2 – 5 cm H2O below PEEP level
– Due to leaks
Ventilator Alarms
• High RR Alarm
– Set 10-15 breaths over observed rate
– Indicates tachypnea and resp distress
– Auto cycling of ventilator
• Low RR Alarm
– Not less than 6 – 8 (preferred) breaths per minute
Ventilator Alarms
• Low exhaled Ve
– 10% - 15% below average minute volume
Ventilator Alarms
• Low exhaled tidal volume
– Set 100-200 ml lower than exhaled Vt
– Could also be estimated at 10% - 15% below set Vt
– Indicates
•
•
•
•
Leaks/Disconnects
Severe air trapping
Decrease compliance in PCV
LOW VTE ALARM WILL SOUND AS HIGH PRESSURE
ALARMS SOUNDS, SINCE VOLUME WILL PREMATURLY
TERMINATE
Ventilator Alarms
• Apnea
– Set back up parameters with 20 second time
interval.
– Ensures a minimum number of breaths will be
delivered to the patient.
Ventilator Alarms
• Oxygen (FiO2)
– 5% above and below set FiO2
Auto PEEP
• Air trapping related to airway obstruction,
rapid RR, long inspiratory times, insufficient
expiratory time.
• Seen with auto peep maneuver and flow vs.
time wave form.
Reducing Auto PEEP
• Reduce airway obstruction through
bronchodilators/steroids.
• Increase expiratory time
– Decrease RR
– Increase inspiratory flow rate
– Decrease tidal volume
– Decrease inspiratory time
Weaning
• If the patient is to be weaned…
– Perform weaning parameters. This may be done through
the ventilator on most modern vents. If you are to do a VC
or MIP, the patient is typically on CPAP mode without PEEP
and minimal PSV if any. Assess VC, MIP, MEP several times
for reproducibility
– While weaning note vital signs, RSBI, Vte, RR, SpO2…
– If patient fatigues to the point that their vitals decline, you
should place them back on previous mode/settings
– You may get a ABG after a short time frame while weaning
to assess effectiveness
– Weaning can be done numerous ways…SBT, CPAP trials, to
Bipap…
Compliance changes
• Static vs dynamic
• Know formula and causes for each
• Static: use inspiratory hold to assess plateau,
increasing plat=decreasing static compliance.
Assess by looking at press-vol loop
• Caused by ARDS, pulm edema, atelectasis,
pneumothorax, obesity…
• Dynamic: Decreased with increases in RAW
Plateau Time
30
Adequate Plateau Time
SEC
Paw
cmH2O
-20
1
2
3
4
5
6
Compliance
• Trend static and dynamic compliance
• Decreasing static compliance= changing to
lung protective strategies, low volumes/high
rates and peep, APRV, HFV…
• Decreasing Dynamic compliance = suction,
bronchodilator, bite block, heated humidity…
Management Options –
Inspiratory Time
 Principle of Use
– Increase in inspiratory time (TI) causes increase in
– Increase in
aids in maintaining integrity of alveoli and
recruiting atelectatic alveoli
– Associated with improvement in
– Associated with improvement of PaO2 in patients with ARDS
Management Options – Bronchial
Hygiene
• Postural drainage
• Percussion
• Adequate humidification
• Ambulation, sitting up, turning patient
Management Options – Patient
Positioning
• Ambulation, sitting up helpful in improving
oxygenation
• Turning patient from side to side aids in
bronchial hygiene
Management Options – Patient
Positioning
Prone Positioning
– May result in dramatic improvement in
oxygenation in patients with ARDS and ALI
– Care must be taken to ensure tubes and lines
are not displaced during turning
– May improve
and reduce shunting by
removing pressure of the heart on the dorsal
regions
Evaluation of Ventilation –
Physical Findings
 Heart Rhythms
– Abnormal rhythms
– Tachycardia
– Bradycardia
 Chest excursion
 Altered Mental State
– Anxiety
– Confusion
– Combativeness
– Somnolence
Evaluation of Ventilation –
Diagnostic Findings
Arterial Blood Gases
– Increased PaCO2
– Decreased pH
– Decreased PaCO2
Bedside Spirometry Results
– Negative inspiratory force (NIF) – < -20 cmH2O
– Spontaneous tidal volume – < 5 mL/kg IBW
– Vital capacity – < 10 mL/kg IBW
Evaluation of Ventilation –
Determine Cause of Problem
Hypoventilation
– Inadequate alveolar ventilation –
A
= (VT – VDS) (f)
– Increase in physiologic dead space –
VD/VT = (PaCO2 – PECO2)/PaCO2
Evaluation of Ventilation –
Determine Cause of Problem
Increase in Carbon Dioxide Production
– Stress
– Shivering
– Pain
– Asynchrony with ventilator
– High carbohydrate diet
Evaluation of Ventilation –
Determine Cause of Problem
Change in Lung and Chest Mechanics
– Compliance – C = ∆V/∆P
• ∆V = VT Corrected for Tubing Compliance
• ∆P = Pplat – PEEP
Causes of decreased lung compliance
– Atelectasis
– Pulmonary edema
– ALI/ARDS
– Pneumothorax
– Fibrosis
Evaluation of Ventilation –
Determine Cause of Problem
 Causes of decreased thoracic compliance
– Obesity
– Pleural effusion
– Ascites
– Chest wall deformity
– Pregnancy
Evaluation of Ventilation –
Determine Cause of Problem
Causes of increased thoracic compliance
– Flail chest
– Loss of chest wall integrity
– Change in patient position
Evaluation of Ventilation –
Determine Cause of Problem
Change in Lung and Chest Mechanics
– Airway Resistance – RAW = ∆P/∆
• ∆P = (Ppeak – Pplat)
• ∆ = flow
Evaluation of Ventilation –
Determine Cause of Problem
 Causes of increased resistance
– Bronchospasm
– Mucosal edema
– Secretions
– Excessively high rate of gas flow
– Small endotracheal tube
– Obstruction of endotracheal tube
– Obstruction of the airway
Evaluation of Ventilation –
Determine Cause of Problem
 Causes of decreased resistance
– Bronchodilator administration
– Decrease in flow of gas
– Administration of bronchial hygiene
Evaluation of Ventilation –
Determine Cause of Problem
• Loss of Muscle Strength/Neurological Input
– Rapid Shallow Breathing Index (RSBI)
• Indication of whether patients have the ability
to breathe without ventilatory support
Evaluation of Ventilation –
Determine Cause of Problem
 Loss of Muscle Strength/Neurological Input
– Rapid Shallow Breathing Index (RSBI)
• f/VT
– If < 100 breaths/min/L, patient has ability to
breathe without ventilator
– If > 100 breaths/min/L, patient will likely not be
able to sustain spontaneous breathing
– Maximal inspiratory pressure
– Maximum voluntary ventilation
Evaluation of Ventilation –
Management Options
Increase Alveolar Ventilation
– Increase in Mechanical Tidal Volume
• Normal Volume – 6 to 12 mL/kg IBW
• Most direct way to change alveolar ventilation
• Should normally not exceed 12 to 15 mL/kg IBW
• Associated with increase in peak inspiratory
pressure which has increased risk of trauma to lung
Evaluation of Ventilation –
Management Options
– Increase in spontaneous ventilation
• More advantageous to patient than increasing
mechanical tidal volume
• Augmentation by pressure support mode helps
overcome resistance of ventilator circuit and artificial
airway
Evaluation of Ventilation –
Management Options
Increase Alveolar Ventilation
– Increase in Mechanical Rate
• Normal Value – 12 to 18 Breaths per Minute
• Should Normally not Exceed 20 Breaths per Minute
• Prediction of Desired Rate
New rate =
Evaluation of Ventilation –
Management Options
 Decrease Carbon Dioxide Output (Production)
– Medicate patient to relieve pain, stress, and
prevent asynchrony, decreasing work of
breathing
– Maintain patient’s temperature within normal
range
– Provide appropriate nutrition
Evaluation of Ventilation –
Management Options
 Treat Underlying Pulmonary Pathophysiology
 Maintain airway in patent state
– Prevent accumulation of secretions in airway
– Use properly sized artificial airway
– Prevent occlusion of airway by patient; use bite
block
Considerations in Management –
Allowing
PaCO2 level
to remain elevated
Permissive
Hypercapnea
above 45 mmHg
• Purpose
– Maintain plateau pressure at an acceptable level
(< 30 cm H2O) by decreasing tidal volume to less
than 6 mL/kg and increasing respiratory rate,
thereby minimizing trauma and cardiovascular
side effects
Considerations in Management –
Permissive Hypercapnea
Method
– Decrease tidal volume and increase respiratory
rate, while maintaining minute volume
– If PaCO2 increases and pH decreases, either
permit normal metabolic compensation or
administer medications to maintain level at 7.25
to 7.35
– Institute gradually to allow PaCO2 to increase
gradually over hours or days
Considerations in Management –
Permissive Hypercapnea
Relative Contraindications or Cautions
– Presence of cardiac ischemia
– Presence of pulmonary hypertension
– Compromised left ventricular function
– Right heart failure
– Head trauma
– Intracranial disease
– Metabolic acidosis
Considerations in Management –
Permissive Hypercapnea
Absolute Contraindication
– Intracranial lesions