Abg’s, cpap, & vents

Respiratory Care for
Paramedics

ABG, CPAP, Ventilation

1-13 Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P 1

Ventilation vs. Respiration

1-13 Voitek A. Novakovski RRT, CCEMT-P 2

Respiratory Cycle, Capacities,
and Volume

Physiology of Respiration


Abnormalities of Respiration
Ventilation / perfusion (V/Q) defect
–  Ratio of pulmonary alveolar ventilation to
pulmonary capillary perfusion is disrupted
–  Normal V/Q ratio is 1:0.8 = VA/CO
–  Area of lung receives ventilation little or no blood
flow = dead space ventilation
u  IncreasedFIO2 results in increased SpO2
u  PCO2 may be normal or increased

–  Area of lung receives blood flow but no
ventilation = shunt unit
u  IncreasedFIO2 does not result in increased SpO2
u  PCO2 may be normal or decreased

© 2011 UMBC Breathing Management CCEMT-P SM
1-13 8

Pathophysiology of
Respiratory Disorders

Shunt Normal Dead Space


Types of Failure
u  Hypoxemic
– Room air PaO2 ≤ 50 or SpO2 ≤ 85%
u  Hypercarbic
– PaCO2 ≥ 50
– pH ≤ 7.32
u  Caution with patients that have acute
on chronic failure
– Their normal SpO2 may be ≈ 88%
– Their normal PCO2 may be ≥ 50

Manifestations of Respiratory Distress
u  Altered Mental Status
u  Increased Work of Breathing
–  Tachypnea -the single most important indicator
of critical illness
–  Accessory muscle use, retractions, paradoxical
breathing pattern
u  Catecholamine release
–  Tachycardia, diaphoresis, hypertension
u  Abnormal blood gas values
–  Oxyhemaglobin Saturation


Pulse Oximetry
u  IR spectroscopy
u  Arterial oxygen saturation
u  False readings
– CO poisoning
– Temperature extremes
– Medications causing vasoconstriction
– Nitrates
– Movement
– Extraneous light sources
14

Oxygen Saturation Curve


Pathophysiology of Hypoxemia
u  Ventilation/Perfusion Mismatch
– Shunt effect
– Increased Dead Space
u Alveolar Hypoventilation
u  Decreased Diffusion
– Pulmonary Contusion
– High Altitude
– Pulmonary Edema


A nasty mosis

Voitek A. Novakovski BSRC, RRT, NREMT-P,
9/11/2011 CCEMT-P, 17

Pathophysiology of Hypercapnia
u  Bradypnia – decreased f (resp rate)
u  Hypopnia – decreased Vt (tidal vol)
a.  VT=VA+VD Average VD=150 ml or≈30%
b.  Minute Volume = the total amount of
air going in and out of the lungs per
minute
c.  Minute Alveolar Ventilation = the total
amount of air going into and out of the
alveoli per minute = f X (VT-VD)


A.  f=12, VT=400ml
A.  ? VA=
B.  f=24, VT=250ml
A.  ? VA=
1. Which patient will have a higher
CO2?



u  Hypovolemia

u  Low cardiac output
u  Pulmonary embolus
u  High mean airway pressures

u  Short-termcompensation by
increasing tidal volume and/
or respiratory rate

Capnography
u  IR spectroscopy
u  CO2 levels at airway entrance

u  Alveolar CO2 levels may be
estimated
u  Excellent detector of cardiac output
– CPR – Keep ETCO2 ≥ 10
– ROSC – Sudden increase to ≥ 35-40

22

Arterial Blood Gas (ABG)
Acid-base balance / respiratory involvement
–  pH, PO2, & PCO2 are measured (HCO3 is
calculated)
–  Assess pH: acidosis / alkalosis e.g. ± pH 7.40
–  Assess pCO2: hyper / hypocapnea ± 40
–  Changes in pH from changes in PCO2
u Acute: 10 mmHg change in PCO2 = 0.08
change in pH
u Chronic: 10 mmHg change in PCO2 = 0.03
change in pH

23

Arterial Blood Gas (ABG)
– There is no such thing as
complete compensation
u If change in pH not from
PCO2 than there is a
metabolic component


ABG Sampling

u  Radial artery puncture
–  Modified Allen Test – needs to
be done
u  Indwelling access
–  Procedure varies by device
u  I-STAT, IRMA etc. portable
blood gas analyzers known as
POC devices. Know the law,
CLIA determines who can
analyze.

25

Quiz Time
2. pH 7.28, PCO2 55, PO2 58
3. pH 7.52, PCO2 25, PO2 48
4. pH 7.25, PCO2 50, PO2 70
5. pH 7.50, PCO2 30, PO2 75
6. pH 7.22, PCO2 34, PO2 94
7. pH 7.37, PCO2 52, PO2 50


Ventilator Management

9/11/2011 Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P 27

Insufflation of Tobacco Smoke
per Rectum

Copyright Intensive Care On-line Network 2002

Ventilator Procedures
In case of instability or
mechanical difficulty,
disconnect the ventilator
and use manual
ventilation.

29

On-Board O2 Calculation
u  To calculate how long an oxygen tank
will last (safety factor ≠! 200 psig)
–  Know the tank factors:
u  H or K = 3.14
u  M = 1.65

u  E = 0.28
u  D = 0.16

u  Tank Life in Minutes =
(tank pressure in psi x factor)
liters per minute
8. You have a Pt on a non-rebreather @ 15 Lpm. You
are using an E cylinder with 1800 psig. How long
will it last before you should change it?
1-13 30

Terminology
u  Fraction of Inspired u  I:E Ratio
Oxygen (FiO2) u  Airway Pressure
u  Tidal Volume (VT) –  Actual
u  Deadspace (VD) –  Mean
–  Peak
u  Frequency (f)
u  Compliance
u  Minute Ventilation (VE)
u  Minute Alveolar u  PEEP
(Positive End
Ventilation (VA)
Expiratory Pressure)/
u  Flow Rate CPAP
u  Inspiratory Time

31

Fraction of Inspired Oxygen
u  Oxygenconcentration, expressed as
fraction in decimal form
– e.g. 50% O2 = FiO2 0.5
– FiO2 of 0.65 = 65% O2

32

Airway Pressure
u  Actual (Paw)
– Real-time airway pressure
u  Mean (MAP)
– Mean pressure over one complete
ventilatory cycle or over a specific
period of time
u  Peak (PIP)
– Highest pressure over a single
ventilatory cycle
SM
CCEMT-P 6/98
33

Inspiratory (I) Time
u  Amount of time to deliver a single
breath, measured in seconds
u  In Time Cycled Ventilation:
I time x flow rate = VT
9. If frequency is 12, and I time is 1.5
seconds, what is the Expiratory (E)
time?
10. How long is each breath cycle
SM
CCEMT-P 6/98
© 2001 UMBC Breathing Management 34

Flow Rate
u  Inspiratory(I) flow measured in lpm
u  Maintain desired I : E ratio

u  Flow may affect pressures

u  In Time Cycled Ventilation:

flow rate x I time = VT
30 Lpm x 1.5 seconds = 750 ml
60 Lpm x 0.5 seconds = 500 ml
11. 40 Lpm x 0.75 second = ? VT
35

I:E Ratio
u  Ratio of time for I:E for normal
breathing is 1:2
u  Clinical situations may require ratio
to change (ET tubes cause resistance
to exhalation and may require longer
expiratory times and I:E of 1:3 or
longer.

36

Compliance
u  Measure
of the willingness of the
lungs to expand with a positive
pressure breath
– Increased compliance
u Lungs are more receptive to a mechanical
breath
u Reflected in lower airway pressures

37

Spontaneous vs. Mechanical
breathing - supine
u  increases ventilation to non-perfused areas
u  increases V/Q mismatch
u  increases posterior consolidation/atelectasis
u  increased diaphragmatic tone decreases
atelectasis
u  decreases venous return and cardiac output

9/11/2011 39
Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P, AE-C

Compliance
– Decreased compliance
u Lungs
are less receptive to a mechanical
breath, and airway pressures increase
–  Patient may be developing a pneumo or
hemothorax,
–  Restrictive lung disease or process such as
pneumonia, or atelecasis
–  Developing ARDS or pulmonary edema
u Patients
with COPD usually have high
compliance with increased expiratory
resistance.


Resistance
u  This is reflected when there is a high
PIP but low plateau pressures and a
long exhalation time.
– Common with Asthma or Acute COPD
exacerbation


Mechanical Ventilation
u  Complications
–  Bio-mechanical Trauma/Pneumothorax
u  Reduced by PEEP
u  Avoid overdistention

–  Airway trauma
Keep head aligned with
u 

torso
–  Atelectasis
u  Humidify the air (HME)
u  Avoid excessive suction

u  Vary Pt’s position

–  Oxygen toxicity
Use the lowest FIO2 that
u 

results in adequate PaO2
–  Device dependence

42

Portable Ventilators
u  Complications

–  Machine failure
–  Hypotension
–  Pulmonary infection
–  GI malfunction
–  Renal malfunction
–  CNS malfunction
–  Psychological trauma

43

Potential Complications of MV
u  Ventilator malfunction
–  Manually ventilate patient
u  Cardiovascular compromise
–  Especially initial hypotension which responds
well to fluid bolus
–  Careful to avoid fluid overload
u  Check BS for crackles
u  Dysrhythmias
–  Monitor vital signs
u  Monitor PIP for changes
–  Breath sound equality

Potential Complications of MV
u  Pulmonary oxygen toxicity
– goal: FIO2 as low as possible while
maintaining a PaO2 > 70, SpO2 ≥ 94%
u  Positive fluid balance
– monitor BP, I/O, and breath sounds
u  Gastric distention
– monitor bowel sounds, NG tube

Principles of Ventilatory Support
u  Oxygenation
– PO2
u Affected by controlling FiO2, FRC, and/or
Mean Paw
u  Ventilation
– pH
– PCO2
u Affectedby controlling VA (Minute Alveolar
Ventilation)

47

Common Mechanical Ventilator
Characteristics (1 of 2)
u  Power source: pneumatic or electric
– External
– Internal
u  Cycling
– Which variable terminates inspiratory
phase of breath: vol, time, flow, or
pressure
u  Breath delivery
– Either positive or negative pressure

Common Mechanical Ventilator
Characteristics (2 of 2)
u  Parameters
– Mode, tidal volume, respiratory rate,
flow, FiO2, PEEP selected by clinician
u  Ventilator circuit
– Reusable or disposable
u  Alarms
– Vary in type
– Set for individual patient, never disabled

Ventilator Setup Procedures
–  FiO2: Always start at 1.0 and adjust by SpO2
–  Select mode (if Pt transport try to mimic
settings of ventilator patient is on)
–  Set respiratory rate
–  Set tidal volume, Insp time, or Pressure
–  Set flow rate; if adjustable
–  Set PEEP
–  Connect ventilator and observe for stability
–  Check PIP, Plateau Pressure, and return Vol,
–  Set alarms
–  Patency of circuitry and all connections
–  Check vital signs, SpO2, and ETCO2

50

Modes of Ventilation
u  Overview
– Control
– Assist/Control
– Synchronized Intermittent Mandatory
Ventilation (SIMV)
– Pressure Control
– Pressure Support
– Continuous Positive Airway Pressure
(CPAP)

51

Control
All parameters of the ventilator cycle
(frequency, VT, flow rate) are
controlled by the ventilator
– Patient is “locked out” from triggering a
breath
– Patient has no active role in ventilatory
cycle
– Rarely used

52

Assist/Control
u  Usually Volume cycled ventilation
– Most popular and easily applied
– Essential parameter to control is volume
delivery, inspiratory flow (time), f (rate),
FiO2, and sensitivity (-2cmH2O)
u  Tidal volume (VT) and minute volume
(VE) are predictable, PIP variable
u  Anxious patients may create stacking

u  Ventilator may be triggered by road
vibrations.
53

9/11/2011 CCEMT-P CCEMT-P, AE-C 54

SIMV or SIMV with PS
u  Ventilator
delivers set number of machine
breaths at set FiO2
–  Respiratory rate, Insp Flow, and VT are set
–  Synchronized with patient’s spontaneous efforts
u  Additional
spontaneous breaths possible
through circuit
–  Spontaneous breaths may Pressure assisted
–  Flow rate and VT are patient controlled
–  Keeps respiratory muscles active and
coordinated
u  Decreases stacking and need for sedation

55

Pressure Control
u  Pressure limited-time cycled ventilation
–  Inspiration ends at a pre-set time and airway
pressure
–  Volume per breath may be variable
–  Often used with ARDS to limit applied pressure
–  Exhaled volume must be monitored closely
–  Not well tolerated by awake patients and
usually requires deep sedation


Pressure Support
u  Pressure limited-flow cycled ventilation
–  Inspiration limited by applied pressure, and ends at a
pre-set terminal flow
–  Volume per breath may be variable
–  Lungs should be relatively free of resistance and
compliant
–  Patient sedated or cooperative
–  Usually support needed for less than 24 hours or
weaning from long term ventilation
–  May be used for long-term chronic support
u  Often used with SIMV to enchance spontaneous
breaths and overcome ET tube resistance.

60

Dual Modes
u  Starts as a Pressure Limited mode which
adjusts the pressure limit on a breath by
breath basis in order to achieve a desired
Tidal Vol (VT) and/or Minute Vol (VE)
u  Utilize the advantages of pressure limited
modes which allow flow to more accurately
meet patient demand.
–  PRVC: Pressure Regulated Volume Control
–  Volume Control Plus
–  Volume Support
–  Automode

62

General Clinical Guidelines
Tidal volume (VT) 6-8 ml/Kg
Respiratory rate (f) 10-14 bpm (ETCO2 35-40)
FiO2 ABG (PO2) or SpO2≥94%
Flowrate 40-60 lpm (I:E ratio)
PIP ≤ 40 cmH2O
Minute volume (VE) ABG(PCO2/pH)ETCO2
Sensitivity -2 cm, adjust as needed
High Pressure Limit 10 cm above PIP
Low Pressure Limit 10 cm below PIP

63

Monitors
u  Airway Pressure (Paw or PIP)
– Real time manometer or graph
– Range: 0-120 cm H2O (depends on vent)
u  Monitor Display
– Breath rate
– Flow
– High pressure alarm
– Low pressure alarm
– PEEP
– I time or I:E
– VT
– VE
64

Ventilator Alarms
u  High airway pressure (PIP)
u  Low airway pressure

u  High respiratory rate

u  Low respiratory rate

u  High minute volume

u  Low minute volume

u  Low exhaled tidal volume

u  Apnea

Ventilator Alarms (con’t)
u  High pressure limit
–  Usually set 10 cm H2O above patient’s average
PIP
–  When activated, ventilator terminates breath
u  Causes of high pressure alarm violation
–  Resistance to gas flow: kinks or water in
tubing, secretions, bronchospasm, patient
coughing, gagging, “fighting the ventilator”
–  Decrease in lung compliance, lungs become
“stiffer”: atelectasis, pneumothorax,
pulmonary edema

u  Low pressure limit
–  Primary cause: patient disconnect, or leak in
system
–  Inspiratory flow too low and patient gasping
for air (increase flow to meet demand)
u  Low exhaled volume or minute ventilation
–  Usually set ~10% below set VT and average VE
–  Ensures adequate alveolar ventilation is
maintained
–  Causes: air leaks, decrease in compliance with
PSV and PCV, high pressure alarm triggered
and breath delivery terminated
–  Check for bubbling in chest tubes

u  High Rate: usually set ≈ 10 over
average rate
– Alarm indicates agitation, hypoxia, or
insufficient VT
– Check vital signs, SpO2, ETCO2, exhaled
VT, or provide sedation
– May be due to “auto-cycling”, check
sensitivity, or check for leaks in circuit


Ventilator Alarms (cont)
u  Highexhaled tidal volume or minute
ventilation
– Increased metabolic demand
– Neurologic abnormality
– May indicate hypoxemia
– Anxiety
– Pain
– Fever
– Acidosis

u  Low
Rate: usually set ≈ 10 below
average rate
– For spontaneous breathing modes like
PS or CPAP this alarm is critical and
indicates either patient is fatigued or
over sedated.
u  Low
tidal volume: usually ≈ 10%
below average or set VT
– Alarm usually due to leak in the system
– In PS or CPAP pt fatigued or over
sedated

u  Apnea
Alarm: this alarm is mostly
used with PS or CPAP:
– Patient has stopped breathing
– May initiate apnea backup ventilation on
some ventilators
u  Disconnect:
some ventilators have
this alarm in addition to a low
pressure alarm.

71

u  Apnea
Alarm: this alarm is mostly
used with PS or CPAP:
– Patient has stopped breathing
– May initiate apnea backup ventilation on
some ventilators
u  Disconnect:
some ventilators have
this alarm in addition to a low
pressure alarm.

Ventilator Alarms (continued)
u  Ventilator Inoperative (some vents)
–  normal operation ceases
u  Breathe room air if spontaneous breathing is present
–  recoverable
u  Lossof external power or voltage out of range
u  Mode switch temporarily set to Off

–  non-recoverable
u  Software or CPU problem
u  External Power Low/Fail
–  Ventilators with this alarm switch to internal
battery

73

u  Battery Low/Fail
– Switch to external power
u  Low PEEP
– Monitored PEEP value deviates from
manually set value: check for leaks in
system
u  Transducer Calibration
– Self test shows baseline pressure +/- 2 cm
H2O from zero
– Calibrate ventilator
74

Flow-Restricted, Oxygen-Powered
Ventilation Device (1 of 4)
u  Third
potential source for artificial
ventilation
– Manually triggered ventilator or demand
valve
– Used to ventilate apneic patients or to
administer supplemental oxygen to
spontaneously breathing patients

Demand valve triggered by the
negative pressure generated during
inhalation
Valve automatically delivers
100% oxygen and stops
the flow of gas at the
end of inhalation.
Patients find it most
comfortable if they
hold the mask to their
face themselves.


u  Apneic patients
–  Pushbutton on top of the FROPVD can control
the flow of oxygen.
–  When depressed, 100% oxygen flows at a rate
of 40 L/min.
u  Requires an oxygen source
–  Operator cannot feel whether the patient is
being adequately ventilated with this device.

u  Use
–  Has been used for several years
–  Recent findings suggest that it should not be
used routinely because of the high incidence of
gastric distention and damage to intrathoracic
structures caused by barotraumas.
–  Should not be used when ventilating infants or
children or for patients with possible cervical
spine or chest injury
–  Cricoid pressure may need to be maintained to
ventilate nonintubated patients.

Skill Drill 11-21:
Ventilation for Apneic Patients (1 of 2)

Step 1

Step 2

Step 3

Skill Drill 11-21:
Ventilation for Apneic Patients (2 of 2)
Step 4 Step 5

Skill Drill 11-22:
Ventilation Device for Conscious,
Spontaneously Breathing Patients

Step 1 Step 2 Step 3

PEEP vs. CPAP

?
? ?
?
?

Lung Volume
TOTAL LUNG CAPACITY (6000 cc)

3100 cc Inspiratory
Reserve
Inspiratory
Capacity

500 cc Tidal volume

Expiratory
1200 cc Reserve
F.R.C.
Functional
Residual
Capacity
Residual
1200 cc Volume


PEEP
u  Positiveend expiratory pressure
u  Increases functional residual
capacity (FRC)

Voitek A. Novakovski BSRC, RRT, NREMT-P, CCEMT-P,
9/11/2011 CCEMT-P AE-C 85

Collateral channels of
ventilation: Pendeluft


PEEP
u  Definition
– Positive End Expiratory Pressure: The
Application of positive pressure to the
airway at end exhalation.
– Used to increase FRC to normal levels.
u  Used with other mechanical ventilation modes
such as A/C, SIMV, PS, or PCV

5 cm H2O
PEEP

CPAP
u  Definition:
PEEP applied to a spontaneously
breathing patient: without mechanical
assist.
–  Continuous Positive Airway Pressure: Constant
positive pressure throughout the ventilatory
cycle
–  Requires spontaneous respiratory drive
–  Rate and VT determined entirely by the patient

10 cm
H2O
PEEP

Time

Spontaneous Breathing


CPAP
u  Must set back-up ventilation
parameters if available
u  Benefits by normalizing FRC:
– Increases compliance
– Decreases atelectasis
– Reduces pulmonary edema
– Increases PaO2
– Decreases work of breathing (WOB)
– Splints airways in Asthma and COPD

92

CPAP
The National Association of EMS Physicians (NAEMSP)
believes that noninvasive positive pressure ventilation
(NIPPV) is an important treatment modality for the
prehospital management of acute dyspnea. This
document is the official position of the NAEMSP.

Read More:
http://informahealthcare.com/doi/abs/
10.3109/10903127.2011.561418


10 Commandments of
Transport Ventilation
1)  Maintain set PEEP (bagging)
2)  Hold ETT when switching
3)  Your vent = their vent
4)  Transition to vent early and observe
5)  Security of airway. Re-tape if necessary
6)  Adequate portable oxygen supply
7)  Judicious use of paralytics or sedatives
8)  Track plateau versus PIP
9)  Maintain EtCO2 and SpO2
10)  Minimal to no changes


Critical Care Ventilator Transport
u  It is important that you set your ventilator to
settings as close as possible to what kept the
patient stable in the hospital. Adjust as needed
u  If you are unable to stabilize the patient on your
ventilator, then a respiratory therapist may be
required to accompany you using the hospital
ventilator, or you may have to refuse transport.
u  If you take their ventilator, make sure it is
compatible with your power source.
u  Do not attempt to transport a patient that is
beyond your capability to maintain.


Pharmacologic Adjuncts
u  Bronchodilators

– β2-agonists
– Anticholinergics (ipratropium)
u  Corticosteroids

u  Sedatives

u  Paralytics

u  Pressors

u  Inotropic agents


Paul Andrate


Quiz
u  Pt 32 y/o intubated on vent, VT
450ml, f 14, FiO2 1.0
– ABG pH 7.37, PCO2 42, PO2 64
– What would you change or add?
u  Pt 17 y/o Asthmatic on 4L/NC with
bilat insp and exp wheezes.
– ABG pH 7.43, PCO2 36, PO2 92
– What 2 classes of drugs plus other
options might help this young man?
1-13 CCEMT-P 98

Noninvasive Positive-Pressure
Ventilation (NPPV)


Relative Contraindications for
NPPV
u  Decreased level of consciousness
u  Poor airway protective reflexes

u  Copious secretions

u  Cardiovascular instability

u  Progressive pulmonary
decompensation
u  Upper gastrointestinal hemorrhage


Initiation of NPPV
u  Set FIO2 at 1.00
u  Hypoxemic failure

– Inspiratory pressure (IPAP) 10 cm H2O
– Expiratory pressure (EPAP) 5 cm H2O
– Titrate EPAP in 2 cm H2O increments
u  Ventilatory failure

– IPAP 10 and EPAP 2 cm H2O
– Titrate IPAP in 2 cm H2O increments

Initiation of NPPV
u  Make changes every 15-30 minutes
u  Monitor vital signs, appearance,
pulse oximetry and blood gases
u  Head of bed at 45° angle

u  Consider gastric decompression

u  Intubation if patient deteriorates

Airway pressure release
ventilation


APRV


APRV
u  Advantages u  Potential
–  Lower peak/plateau disadvantages
–  Spontaneous –  Change in compliance
breathing permitted = change in volume
–  Decreased sedation –  New technology
–  Elimination of NMB –  Limited access
u  (Frawley & Habashi –  More research
2001)
–  Transports


Abg’s, cpap, & vents

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