NON-INVASIVE CAPNOGRAPHY

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NON-INVASIVE CAPNOGRAPHY
ALS Blue In-Service Part III
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Oxygenation and Ventilation

• What is the difference?

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Oxygenation and Ventilation
Ventilation (capnography)
Oxygenation (oximetry)
O2
Cellular Metabolism
CO2
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Oximetry and Capnography

• Pulse oximetry measures oxygenation
• Capnography measures ventilation and provides a
  graphical waveform available for interpretation

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Oxygenation

• Measured by pulse oximetry (SpO2)
• Noninvasive measurement
• Percentage of oxygen in red blood cells
• Changes in ventilation take minutes to be
  detected
• Affected by motion artifact, poor perfusion and
  some dysrhythmias

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Oxygenation
Pulse Oximetry Sensors
Pulse Oximetry Waveform
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Ventilation

• Measured by the end-tidal CO2
• Partial pressure (mmHg) or volume ( vol) of CO2
  in the airway at the end of exhalation
• Breath-to-breath measurement provides
  information within seconds
• Not affected by motion artifact, poor perfusion
  or dysrhythmias

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Ventilation
Capnography Lines
Capnography waveform
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Oxygenation and Ventilation

• Oxygenation
• Oxygen for metabolism
• SpO2 measures of O2 in RBC
• Reflects change in oxygenation within 5 minutes

• Ventilation
• Carbon dioxide from metabolism
• EtCO2 measures exhaled CO2 at point of exit
• Reflects change in ventilation within 10 seconds

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Oxygenation versus Ventilation

• Monitor your own SpO2 and EtCO2
• SpO2 waveform is in the second channel
• EtCO2 waveform is in the third channel

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Oxygenation versus Ventilation

• Now hold your breath
• Note what happens to
  the two
  waveforms

SpO2
EtCO2
How long did it take the EtCO2 waveform to go
flat line?
How long did it take the SpO2 to drop below 90?
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• Numeric reading HR 100
• Waveform

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• Numeric reading HR 100
• Waveform

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Capnography in EMS
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Capnography in EMS

• Low-flow sidestream technology

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Using Capnography

• Immediate information via breath-to-breath
  monitoring
• Information on the ABCs
• Airway
• Breathing
• Circulation
• Documentation

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Using Capnography

• Airway
• Verification of ET tube placement
• Continuous monitoring of ET tube position
• Circulation
• Check effectiveness of cardiac compressions
• First indicator of ROSC
• Monitor low perfusion states

Airway
Circulation
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Using Capnography

• Breathing
• Hyperventilation
• Hypoventilation
• Asthma
• COPD

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Using Capnography

• Documentation
• Waveforms
• Initial assessment
• Changes with treatment
• EtCO2 values
• Trends over time

Waveforms
Trends
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Why Measure VentilationIntubated Patients

• Verify and document ET tube placement
• Immediately detect changes in ET tube position
• Assess effectiveness of chest compressions
• Earliest indication of ROSC
• Indicator of probability of successful
  resuscitation
• Optimally adjust manual ventilations in patients
  sensitive to changes in CO2

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• A 2005 study comparing field intubations that
  used capnography to confirm ETT placement vs.
  non-capnography use showed a 0 unrecognized
  misplaced ETT and 23 in the non-EtCO2 monitored
  group
• Confirm ETI with waveform capnography!!

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Why Measure VentilationNon-Intubated Patients

• Objectively assess acute respiratory disorders
• Asthma
• COPD
• Possibly gauge response to treatment

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Why Measure VentilationNon-intubated Patients

• Gauge severity of hypoventilation states
• Drug and ETOH intoxication
• Congestive heart failure
• Sedation and analgesia
• Stroke
• Head injury
• Assess perfusion status
• Noninvasive monitoring of patients in DKA

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End-tidal CO2 (EtCO2)
Pulmonary Blood Flow
Ventilation
Left Atrium
Right Ventricle
Perfusion
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a-A Gradient
arterial to Alveolar Difference for CO2
Ventilation
Left Atrium
Right Ventricle
Alveolus
r
r
V
e
i
n
A
t
e
y
EtCO2
PaCO2
Perfusion
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End-tidal CO2 (EtCO2)

• Normal a-A gradient
• 2-5mmHg difference between the EtCO2 and PaCO2
  in a patient with healthy lungs
• Wider differences found
• In abnormal perfusion and ventilation
• Incomplete alveolar emptying
• Poor sampling

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End-tidal CO2 (EtCO2)

• Reflects changes in
• Ventilation - movement of air in and out of the
  lungs
• Diffusion - exchange of gases between the
  air-filled alveoli and the pulmonary circulation
• Perfusion - circulation of blood

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End-tidal CO2 (EtCO2)

• Monitors changes in
• Ventilation - asthma, COPD, airway edema, foreign
  body, stroke
• Diffusion - pulmonary edema, alveolar damage, CO
  poisoning, smoke inhalation
• Perfusion - shock, pulmonary embolus, cardiac
  arrest, severe dysrhythmias

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Physiological Factors Affecting ETCO2 Levels
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Interpreting EtCO2 and the Capnography Waveform

• Interpreting EtCO2
• Measuring
• Physiology
• Capnography waveform

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Capnographic Waveform

• Normal waveform of one respiratory cycle
• Similar to ECG
• Height shows amount of CO2
• Length depicts time

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Phase 1

• First Upstroke of the capnogram waveform
• Represents of gas exhaled from upper airways
  (I.e. anatomical dead space)

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Phase 2

• Transitional Phase from upper to lower airway
  ventilation, and tends to depict changes in
  perfusion

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Phase 3

• Represents alveolar gas exchange, which indicates
  changes in gas distribution
• All increases of the slope of Phase 3 indicates
  increased maldistribution of gas delivery

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Capnographic Waveform

• Waveforms on screen and printout may differ in
  duration
• On-screen capnography waveform is condensed to
  provide adequate information the in 4-second view
• Printouts are in real-time
• Observe RR on device

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Capnographic Waveform

• Capnograph detects only CO2 from ventilation
• No CO2 present during inspiration
• Baseline is normally zero

Baseline
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Capnogram Phase IDead Space Ventilation

• Beginning of exhalation
• No CO2 present
• Air from trachea, posterior pharynx, mouth and
  nose
• No gas exchange occurs there
• Called dead space

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Deadspace
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Capnogram Phase I Baseline
B
A
I
Baseline
Beginning of exhalation
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Capnogram Phase IIAscending Phase

• CO2 from the alveoli begins to reach the upper
  airway and mix with the dead space air
• Causes a rapid rise in the amount of CO2
• CO2 now present and detected in exhaled air

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Capnogram Phase IIAscending Phase
C
Ascending Phase Early Exhalation
II
B
A
CO2 present and increasing in exhaled air
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Capnogram Phase IIIAlveolar Plateau

• CO2 rich alveolar gas now constitutes the
  majority of the exhaled air
• Uniform concentration of CO2 from alveoli to
  nose/mouth

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Capnogram Phase IIIAlveolar Plateau
Alveolar Plateau

• CO2 exhalation wave plateaus

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Capnogram Phase IIIEnd-Tidal

• End of exhalation contains the highest
  concentration of CO2
• The end-tidal CO2
• The number seen on your monitor
• Normal EtCO2 is 35-45mmHg

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Capnogram Phase IIIEnd-Tidal
D
C
End-tidal
A
B

• End of the the wave of exhalation

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Capnogram Phase IVDescending Phase

• Inhalation begins
• Oxygen fills airway
• CO2 level quickly drops to zero

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Capnogram Phase IVDescending Phase
C
D
Descending Phase Inhalation
I
V
A
B
E

• Inspiratory downstroke returns to baseline

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Capnography Waveform
Normal Waveform

• Normal range is 35-45mm Hg (5 vol)

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Capnography Waveform Question

• How would your capnogram change if you
  intentionally started to breathe at a rate of 30?
• Frequency
• Duration
• Height
• Shape

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Hyperventilation

• RR EtCO2

Normal
Hyperventilation
4
5
0
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Waveform Regular Shape, Plateau Below Normal

• Indicates CO2 deficiency
• Hyperventilation
• Decreased pulmonary perfusion
• Hypothermia
• Decreased metabolism
• Interventions
• Adjust ventilation rate
• Evaluate for adequate sedation
• Evaluate anxiety
• Conserve body heat

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Capnography Waveform Question

• How would your capnogram change if you
  intentionally decreased your respiratory rate to
  8?
• Frequency
• Duration
• Height
• Shape

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Hypoventilation
RR EtCO2

Normal
Hypoventilation

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Waveform Regular Shape, Plateau Above Normal

• Indicates increase in ETCO2
• Hypoventilation
• Respiratory depressant drugs
• Increased metabolism
• Interventions
• Adjust ventilation rate
• Decrease respiratory depressant drug dosages
• Maintain normal body temperature

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Capnography Waveform Patterns
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Capnography Waveform Question

• How would the waveform shape change during an
  asthma attack?

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Bronchospasm Waveform Pattern

• Bronchospasm hampers ventilation
• Alveoli unevenly filled on inspiration
• Empty asynchronously during expiration
• Asynchronous air flow on exhalation dilutes
  exhaled CO2
• Alters the ascending phase and plateau
• Slower rise in CO2 concentration
• Characteristic pattern for bronchospasm
• Shark Fin shape to waveform

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Capnography Waveform Patterns
Normal
Bronchospasm
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Capnography Waveform Patterns
Normal
Hyperventilation
Hypoventilation
Bronchospasm
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The Intubated Patient
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Confirm ET Tube Placement
4
5
0
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Detect ET Tube Displacement

• Capnography
• Immediately detects ET tube displacement

Source Murray I. P. et. al. 1983. Early
detection of endotracheal tube accidents by
monitoring CO2 concentration in respiratory gas.
Anesthesiology 344-346
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Detect ET Tube Displacement

• Only capnography provides
• Continuous numerical value of EtCO2 with apnea
  alarm after 30 seconds
• Continuous graphic waveform for immediate visual
  recognition

Source Linko K. et. al. 1983. Capnography for
detection of accidental oesophageal intubation.
Acta Anesthesiol Scand 27 199-202
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Confirm ET Tube Placement

• Capnography provides
• Documentation of correct placement
• Ongoing documentation over time through the
  trending printout
• Documentation of correct position at ED arrival

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Capnography in Cardiopulmonary Resuscitation

• Assess chest compressions
• Early detection of ROSC
• Objective data for decision to cease resuscitation

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CPR Assess Chest Compressions

• Use feedback from EtCO2 to depth/rate/force of
  chest compressions during CPR

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CPR Detect ROSC

• Briefly stop CPR and check for organized rhythm
  on ECG monitor

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ETCO2 Cardiac Resuscitation

• Non-survivors
• Average ETCO2 4-10 mmHg
• Survivors (to discharge)
• Average ETCO2 gt30 mmHg

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Optimize Ventilation

• Use capnography to titrate EtCO2 levels in
  patients sensitive to fluctuations
• Patients with suspected increased intracranial
  pressure (ICP)
• Head trauma
• Stroke
• Brain tumors
• Brain infections

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Optimize Ventilation

• High CO2 levels induce cerebral vasodilatation
• Positive Increases CBF to counter cerebral
  hypoxia
• Negative Increased CBF, increases ICP and may
  increase brain edema
• Hypoventilation retains CO2 which increases levels

CO2
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Optimize Ventilation

• Low CO2 levels lead to cerebral vasoconstriction
• Positive EtCO2 of 25-30mmHG causes a mild
  cerebral vasoconstriction which may decrease ICP
• Negative Decreased ICP but may cause or
  increase in cerebral hypoxia
• Hyperventilation decreases CO2 levels

CO2
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Optimize Ventilation

• Treatment goals
• Avoid cerebral hypoxia
• Monitor blood oxygen levels with pulse oximetry
• Maintain adequate CBF
• Target EtCO2 of 35 mmHg

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The Non-intubated Patient
CC trouble breathing
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The Non-intubated Patient CC trouble
breathing
PE?
Asthma?
Emphysema?
Bronchitis?
Pneumonia?
Cardiac ischemia?
CHF?
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The Non-intubated Patient Capnography
Applications

• Identify and monitor bronchospasm
• Asthma
• COPD
• Assess and monitor
• Hypoventilation states
• Hyperventilation
• Low-perfusion states

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Capnography in Bronchospastic Conditions

• Air trapped due to irregularities in airways
• Uneven emptying of alveolar gas
• Dilutes exhaled CO2
• Slower rise in CO2 concentration during
  exhalation

A
l
v
e
o
l
i
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Capnography in Bronchospastic Diseases

• Uneven emptying of alveolar gas alters emptying
  on exhalation
• Produces changes in ascending phase (II) with
  loss of the sharp upslope
• Alters alveolar plateau (III) producing a shark
  fin

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Capnography in Bronchospastic ConditionsCapnogram
of Asthma
Changes in dCO2/dt seen with increasing
bronchospasm
Source Krauss B., et al. 2003. FEV1 in
Restrictive Lung Disease Does Not Predict the
Shape of the Capnogram. Oral presentation. Annual
Meeting, American Thoracic Society, May, Seattle,
WA
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Capnography in Bronchospastic ConditionsAsthma
Case Scenario
Initial
After therapy
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Capnography in Bronchospastic ConditionsPathology
of COPD

• Progressive
• Partially reversible
• Airways obstructed
• Hyperplasia of mucous glands
  and smooth muscle
• Excess mucous production
• Some hyper-responsiveness

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Capnography in Bronchospastic ConditionsCapnograp
hy in COPD

• Arterial CO2 in COPD
• PaCO2 increases as disease progresses
• Requires frequent arterial punctures for ABGs
• Correlating capnograph to patient status
• Ascending phase and plateau are altered by uneven
  emptying of gases

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Capnography in Bronchospastic ConditionsCOPD
Case Scenario
Initial Capnogram A
Initial Capnogram B
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Capnography in CHFCase Scenario

• 88 year old male
• C/O Short of breath
• H/O MI X 2, on oxygen at 2 L/m
• Pulse 66, BP 164/86, RR 36 labored and shallow,
  skin cool and diaphoretic, 2 pedal edema
• Initial SpO2 69 EtCO2 17mmHG

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Capnography in CHFCase Scenario

• Placed on non-rebreather mask with 100 oxygen at
  15 L/m and aggressive SL nitroglycerin as per
  protocol
• Ten minutes after treatment
• SpO2 69 99
• EtCO2 17mmHG 35 mmHG

Time condensed to show changes
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Capnography in Hypoventilation States

• Altered mental status
• Sedation
• Alcohol intoxication
• Drug Ingestion
• Stroke
• CNS infections
• Head injury
• Abnormal breathing
• CO2 retention
• EtCO2 gt50mmHg

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Capnography in Hypoventilation States
Time condensed actual rate is slower

• EtCO2 is above 50mmHG
• Box-like waveform shape is unchanged

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Capnography in Hypoventilation States
Hypoventilation
Time condensed actual rate is slower

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Capnography in Hypoventilation States
Hypoventilation

• Hypoventilation in shallow breathing

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Capnography in Low Perfusion

• Capnography reflects changes in
• Perfusion
• Pulmonary blood flow
• Systemic perfusion
• Cardiac output

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Capnography in Low PerfusionCase Scenario

• 57 year old male
• Motor vehicle crash with injury to chest
• History of atrial fib, anticoagulant
• Unresponsive
• Pulse 100 irregular, BP 88/p
• Intubated on scene

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Capnography in Low PerfusionCase Scenario
Low EtCO2 seen in low cardiac output
Ventilation controlled
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Capnography in Pulmonary EmbolusCase Scenario
Strong radial pulse Low EtCO2 seen in decreased
alveolar perfusion
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Capnography in Rebreathing Circumstances
Elevated Baseline
4
5
0

• Baseline elevation

• Oxygen mask
• Poor head and neck alignment
• Shallow breathing not clearing deadspace

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Capnography in DKACase Scenario
Rapid rate, normal waveform and elevated EtCO2
seen in early respiratory compensation in DKA
Source Flanagan, J.F., et al. 1995. Noninvasive
monitoring of end-tidal carbon dioxide tension
via nasal cannulas in spontaneously breathing
children with profound hypocarbia. Critical Care
Medicine. June 23 (6) 1140-1142
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Capnography Applicationson Non-intubated Patients

• New applications now being reported
• Pulmonary emboli
• CHF
• DKA
• Bioterrorism
• Others?

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Quiz Time!
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Sudden Loss of Waveform

• Apnea
• Airway Obstruction
• Dislodged airway (esophageal)
• Airway disconnection
• Ventilator malfunction
• Cardiac Arrest

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Increase in ETCO2

• Possible causes
• Decrease in respiratory rate (Hypoventilation)
• Decrease in tidal volume
• Increase in metabolic rate
• Rapid rise in body temperature (hyperthermia)

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Esophageal Tube

• A normal capnogram is the best evidence that the
  ETT is correctly positioned
• With an esophageal tube little or no CO2 is
  present

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Rebreathing

• Possible causes
• Faulty expiratory valve
• Inadequate inspiratory flow
• Insufficient expiratory flow

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Inadequate Seal Around ETT

• Possible causes
• Leaky or deflated endotracheal or tracheostomy
  cuff
• Artificial airway too small for the patient

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Decrease in ETCO2

• Possible causes
• Increase in respiratory rate (Hyperventilation)
• Increase in tidal volume
• Decrease in metabolic rate
• Fall in body temperature (hypothermia)

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Obstruction

• Possible causes
• Partially kinked or occluded artificial airway
• Presence of foreign body in the airway
• Obstruction in expiratory limb of the breathing
  circuit
• Bronchospasm

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Muscle Relaxants

• Curare Cleft
• Appears when muscle relaxants begin to subside
• Depth of cleft is inversely proportional to
  degree of drug activity

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You Survived!

• Thanks!
• Questions to me via groupwise
• jcushman_at_co.ho.md.us