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CAPNOGRAPHY
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical application
• Carry home
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical application
• Carry home
• 1943- luft –CO2 absorbs infrared light
• Ramwell – proved it beyond doubt
• 1978- holland the first country to adopt
• 1999 – ISA ‗desirable standard‘ in
anaesthesia monitoring standards
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical application
• Carry home
terminology
• Capnometry
• Capnometer
• Capnography
• Capnogram
• Capnograph
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical application
• Carry home
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
• Capnography provides information about
CO2 production, pulmonary perfusion,
alveolar ventilation, respiratory patterns,
and elimination of CO2 from the
anesthesia circuit and ventilator.
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
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
Why Capnography ?
• Capnography, an indirect monitor
helps in the differential diagnosis of hypoxia
to enable remedial measures to be taken before
hypoxia results in an irreversible brain damage
• Capnography has been shown to be effective in
the early detection of adverse respiratory events.
• Capnography and pulse oximetry together
could have helped in the prevention of
93% of avoidable anesthesia mishaps
according to ASA closed claim study.
• Capnography has also been shown to
facilitates better detection of potentially
life-threatening problems than clinical
judgment alone
Case Scenario
• 61 year old male
• C/O: ―short-of-breath‖ and ―exhausted‖
• H/O: > 45 years of smoking 2 packs a day,
3 heart attacks, high blood pressure
• Meds: ―too expensive to take every day ‖
• Exam: HR 92, RR 18, 160/100, 2+ pitting
edema, wheezing, crackles
What other information would help in
making assessment of this pt.?
Why Measure Ventilation—
Non-Intubated Patients
• Objectively assess acute
respiratory disorders
– Asthma
– COPD
• Possibly gauge response to treatment
Why Measure Ventilation—
Non-intubated Patients
• Gauge severity of hypoventilation states
– Drug intoxication
– Congestive heart failure
– Sedation and analgesia
– Stroke
– Head injury
• Assess perfusion status
• Noninvasive monitoring of patients in DKA
• History
• Terminology
• Why capnography
• Basic physiology
• Physics
• Types
• Components of capnography
• Clinical application
• Carry home
CO2 transport
• 60% as bicarbonate ion
• 10-20% binds to amino group of proteins
mostly hemoglobin
HALDANE EFFECT
• 5-10% directly dissolved in plasma
End-tidal CO2 (EtCO2)
r r Oxygen
O
2
CO2
O
2
VeinA te y
Ventilation
Perfusion
Pulmonary Blood Flow
Right
Ventricle
Left
Atrium
End-tidal CO2 (EtCO2)
• Carbon dioxide can be measured
• Arterial blood gas is PaCO2
– Normal range: 35-45mmHg
• Mixed venous blood gas PeCO2
– Normal range: 46-48mmHg
• Exhaled carbon dioxide is EtCO2
– Normal range: 35-45mmHg
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
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
a-A Gradient
r r Alveolus
PaCO2
VeinA te y
Ventilation
Perfusion
Arterial to Alveolar Difference for CO2
Right
Ventricle
Left
Atrium
EtCO2
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
Negative a-A gradient
• Pregnancy
• Infants and children
• During and after bypass
• after coming of cardiac bypass
• Low frequency high tidal volume
ventilation
• History
• Terminology
• Why capnography
• Basic physiology
• Physics
• Types
• Components of capnography
• Clinical application
• Carry home
Raman effect
• Electromagnetic radiation and molecule
• The transfer of energy affects the vibration
energy associated with bonds between the
atoms in a molecule
• Absorption of radiation at a particular
wave length is associated with the specific
type of bond between atoms in a
molecule.
Absorption of radiation depends on
the wavelength of radiation
• Energy of radiation is proportional to the
frequency of radiation
• the transfer of energy between the
radiation and molecule results in a change
in the wavelength of radiation
Raman spectrography
• Raman Spectrography uses the principle of "Raman
Scattering" for CO2 measurement.
• The gas sample is aspirated into an analyzing
chamber, where the sample is illuminated by a high
intensity monochromatic argon laser beam.
• The light is absorbed by molecules which are then
excited to unstable vibrational or rotational energy
states (Raman scattering).
• The Raman scattering signals (Raman light) are of low
intensity and are measured at right angles to the laser
beam.
• The spectrum of Raman scattering lines can be used
to identify all types of molecules in the gas phase
Mass spectrograpy
Capnography
Chemical method of CO2 measurement -
pH sensitive chemical indicator
Effect of atmospheric pressure
• FEtCO2=partial pressure(atmospheric
pressure-water vapour pressure)*100
• At atm pressure of 760mmHg,
FEtCO2=38(760-47)*100 =5%
at atm pressure of 500mmHg
FEtCO2=38(500-47)*100 =8%
Influence of water vapour
1. Effect of condensed water:
Water vapor may condense on the
window of the sensor cell and absorb IR
light, thereby produce falsely high C02
readings
2. Effect of water vapor.
The temperature of the sampling gases
may decrease during the passage from the
patient to the unit, resulting in a decrease in
the partial pressure of water vapor. This can
cause an apparent increase in C02
concentration of about 1.5-2%
FEtCO2=partial pressure(atmospheric
pressure-water vapour pressure)*100
• History
• Terminology
• Why capnography
• Basic physiology
• Physics
• Types
• Components of capnography
• Clinical application
• Carry home
Volume capnography Time capnography
Time capnography
Advantages
• Simple and convenient
• Monitor non-intubated patients
• Monitor dynamics of inspiration and
expiration
Disadvantages
• Poor estimation of V/Q status of lungs
• Physiologic space dead space
Sidestream
Side-stream Capnographs
advantages
Easy to connect
No problems with sterilization
Can be used in awake patients
Easy to use when patient is in
unusual positions such as in prone
position
Can be used in collaboration with
simultaneous oxygen
administration via a nasal prong
disadvantages
Delay in recording due to movement
of gases from the ET to the unit
Sampling tube obstruction
Water vapor pressure changes
affect CO2 concentrations
Pressure drop along the sampling
tube affects CO2 measurements
Sampling of CO2 from nasal cannulae
Adequacy of spontaneous respiration
Sampling of
CO2 from
oxygen mask
mainstream
Mainstream
• Advantages
No sampling tube
No obstruction
No affect due to pressure drop
No affect due to changes in water
vapor pressure
No pollution
No deformity of capnograms due to
non dispersion of gases
No delay in recording
Suitable for neonates and children
• Disadvantages
weight of the sensor, (the newer
sensors are light weight minimizing
traction on the endotracheal tube)
Long electrical cord, but it is
lightweight.
Sensor windows may clog with
secretions( they can be replaced
easily as they are disposable)
Difficult to use in unusual patient
positioning such as in prone
positions.
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical application
• Carry home
Capnographic Waveform
• Normal waveform of one respiratory cycle
• Similar to ECG
– Height shows amount of CO2
– Length depicts time
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
Capnographic Waveform
• Capnograph detects only CO2
from ventilation
• No CO2 present during inspiration
– Baseline is normally zero
A B
C D
E
Baseline
Phase I Dead space ventillation
Beginning of exhalation
A B
IBaseline
Phase II Ascending Phase
Alveoli
CO2 present and increasing in exhaled air
II
A
B
C
Ascending Phase
Early Exhalation
Phase III Alveolar Plateau
CO2 exhalation wave
plateaus
A B
C D
III
Alveolar Plateau
Capnogram Phase III
End-Tidal
End of the the wave of exhalation contains the
highest concentration of CO2 - number seen on
monitor
A B
C D
End-tidal
Capnogram Phase IV
Descending Phase
• Inhalation begins
• Oxygen fills airway
• CO2 level quickly
drops to zero
Alveoli
Capnogram Phase IV
Descending Phase
Inspiratory downstroke returns to baseline
A B
C D
E
IV
Descending Phase
Inhalation
Inspiratory segment
• Phase 0:
Inspiration
• Beta Angle - Angle
between phase III
and descending
limb of inspiratory
segment
Expiratory segment
• Phase I - Anatomical
dead space
• Phase II - Mixture of
anatomical and
alveolar dead space
• Phase III - Alveolar
plateau
• Alfa angle - Angle
between phase II and
phase III (V/Q status of
lung
Capnography Waveform
Normal range is 35-45mm Hg (5% vol)
Normal Waveform
45
0
Capnography Waveform Patterns
0
45
Hypoventilation RR : EtCO2
45
0
Hyperventilation RR : EtCO2
45
0
Normal
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical application
• Carry home
Capnography-3 sources of information
• No. – PEtCO2 values
• Shapes of capnogram
• (a-ET)PCO2 differences
(a-ET)PCO2 differences
• (a-ET)PCO2 difference is a gradient of
alveolar dead space.
increase decrease
Age
Emphysema
Low cardiac output
states
Hypovolemia
Pulmonary embolism
Pregnancy and
Children
Five characteristics of capnogram
should be evaluated
The shape of a capnogram is identical in all
humans with healthy lungs.
Any deviations in shape must be investigated to
determine a physiological or a pathological cause
of the abnormality
• Frequency
• Rhythm
• Height
• Baseline
• Shape
Resuscitation- trend
• A terminal upswing
at the end of phase
3, known as phase
4, can occur in
pregnant subjects,
obese subjects
and low
compliance states
The slope the expiratory plateau is increased as a
normal physiological variation in pregnancy
Prolonged inspiratory descending limb
• due to dispersion
gases in the sampling
line or as well as
prolonged response
time of the analyzer.
Seen in children who
have faster
respiratory rates
Base line elevated in
• Inadequate fresh gas flow
• Accidental administration of CO2
• Rebreathing
• Insp / exp valve malfunction
• Exhausted CO2 absorber
Elevation of base line
Contamination of CO2 monitor
• sudden elevation
of base line and
top line
Expiratory valve malfunction
• Expiratory valve
malfunction can
result in prolonged
abnormal phase 2
and phase 0
Inspiratory valve malfunction
• Elevation of the
base line,
prolongation of
down stroke,
prolongation of
phase III
Bain circuit
• Inspiratory base
line and phase I
are elevated above
the zero due to
rebreathing. Note
the rebreathing
wave during
inspiration.
Hypoventilation
• Gradual elevation
of the height of the
capnogram, base
line remaining at
zero
hyperventillation
• Gradual decrease
in the height of the
capnogram, base
line remaining at
zero
Oesophageal intubation
Capnography
Capnography
Cardiogenic oscillations.
• Ripple effect,
superimposed on
the plateau and the
descending limb,
resulting from
small gas
movements
produced by
pulsations of the
aorta and heart.
Airway obstruction (eg., bronchospasm). Phase II and phase III
are prolonged and alpha angle (angle between phase II and
phase III) is increased
bronchospasm
during After relief
Curare effect
Malignant hyperpyrexia
hypothermia
• A gradual decrease in
end tidal carbon
dioxide
hypothermia,
reduced metabolism,
hyperventilation,
leaks in the sampling
system
Kyphoscoliosis
• The CO2 waveform
has two humps.
resulted in a
compression of
the right lung
• Capnogram during
spontaneous
ventilation in
adults
• Sampling
problems such air
or oxygen dilution
during nasal or
mask sampling of
carbon dioxide in
spontaneously
breathing patients.
Detection of pulmonary air embolism
• A rapid decrease of PETCO2
in the absence of changes in
blood pressure, central
venous pressure and heart
rate indicates an air embolism
without systemic
hemodynamic consequences.
• as the size of air embolism
increases, a reduction in
cardiac output occurs which
further decreases PETCO2
measurement. A reduced
cardiac output by itself can
decrease PETCO2.
Effective circulating blood volume can
reduce the height of capnograms
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical application
• Carry home
Phases of the Capnogram
Phase I
Expiration
Represents
anatomical
dead space
Phase II
Expiration
Mixture of
anatomical and
alveolar dead
space
Phase III
Expiration
Plateau of
alveolar
expiration
Phase 0
Inspiration
Rapid fall
in CO2
concentration
Phase IV
Exhalation
Compromised
thoracic
compliance
Hyperventilation
Progressively lower plateau (phase II) segment
Baseline remains at zero
Decreasing CO2 levels
Hypoventilation
Steady increase in height of Phase II
Baseline remains constant
Spontaneous Ventilation
Short Alveolar plateau
Increased frequency of waveforms
Cardiogenic Oscillations
Ripples during Phase II and Phase III
Due to changes in pulmonary blood volume and
ultimately CO2 pressure as a result of cardiac
contractions
Curare Cleft
Shallow dips in phase II plateau
Can occur when patient is in a light plane of
anesthesia
Represent patient attempts to breathe independent of mechanical ventilation
Bronchospasm
Airway Obstruction
COPD Sloping of inspiratory and expiratory segments
Prolonged Phase II and Phase III
Rebreathing of Soda Lime
Contamination with CO2
Elevation of Phase II segment and
baseline
Elevation of baseline and Phase II, smaller inspiratory efforts
Progressive elevation of Phase II and baseline
Bain System
Smaller wave form represents rebreathing of CO2
Slow ventilation
Incompetent inspiratory valve
Prolongation of Phase 0
Capnography
• Capnography provides
another objective data
point in making a
difficult decision

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Capnography

  • 2. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  • 3. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  • 4. • 1943- luft –CO2 absorbs infrared light • Ramwell – proved it beyond doubt • 1978- holland the first country to adopt • 1999 – ISA ‗desirable standard‘ in anaesthesia monitoring standards
  • 5. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  • 6. terminology • Capnometry • Capnometer • Capnography • Capnogram • Capnograph
  • 7. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  • 8. 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
  • 9. • Capnography provides information about CO2 production, pulmonary perfusion, alveolar ventilation, respiratory patterns, and elimination of CO2 from the anesthesia circuit and ventilator.
  • 10. 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
  • 11. 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
  • 12. Why Capnography ? • Capnography, an indirect monitor helps in the differential diagnosis of hypoxia to enable remedial measures to be taken before hypoxia results in an irreversible brain damage • Capnography has been shown to be effective in the early detection of adverse respiratory events.
  • 13. • Capnography and pulse oximetry together could have helped in the prevention of 93% of avoidable anesthesia mishaps according to ASA closed claim study. • Capnography has also been shown to facilitates better detection of potentially life-threatening problems than clinical judgment alone
  • 14. Case Scenario • 61 year old male • C/O: ―short-of-breath‖ and ―exhausted‖ • H/O: > 45 years of smoking 2 packs a day, 3 heart attacks, high blood pressure • Meds: ―too expensive to take every day ‖ • Exam: HR 92, RR 18, 160/100, 2+ pitting edema, wheezing, crackles What other information would help in making assessment of this pt.?
  • 15. Why Measure Ventilation— Non-Intubated Patients • Objectively assess acute respiratory disorders – Asthma – COPD • Possibly gauge response to treatment
  • 16. Why Measure Ventilation— Non-intubated Patients • Gauge severity of hypoventilation states – Drug intoxication – Congestive heart failure – Sedation and analgesia – Stroke – Head injury • Assess perfusion status • Noninvasive monitoring of patients in DKA
  • 17. • History • Terminology • Why capnography • Basic physiology • Physics • Types • Components of capnography • Clinical application • Carry home
  • 18. CO2 transport • 60% as bicarbonate ion • 10-20% binds to amino group of proteins mostly hemoglobin HALDANE EFFECT • 5-10% directly dissolved in plasma
  • 19. End-tidal CO2 (EtCO2) r r Oxygen O 2 CO2 O 2 VeinA te y Ventilation Perfusion Pulmonary Blood Flow Right Ventricle Left Atrium
  • 20. End-tidal CO2 (EtCO2) • Carbon dioxide can be measured • Arterial blood gas is PaCO2 – Normal range: 35-45mmHg • Mixed venous blood gas PeCO2 – Normal range: 46-48mmHg • Exhaled carbon dioxide is EtCO2 – Normal range: 35-45mmHg
  • 21. 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
  • 22. 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
  • 23. a-A Gradient r r Alveolus PaCO2 VeinA te y Ventilation Perfusion Arterial to Alveolar Difference for CO2 Right Ventricle Left Atrium EtCO2
  • 24. 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
  • 25. Negative a-A gradient • Pregnancy • Infants and children • During and after bypass • after coming of cardiac bypass • Low frequency high tidal volume ventilation
  • 26. • History • Terminology • Why capnography • Basic physiology • Physics • Types • Components of capnography • Clinical application • Carry home
  • 27. Raman effect • Electromagnetic radiation and molecule • The transfer of energy affects the vibration energy associated with bonds between the atoms in a molecule • Absorption of radiation at a particular wave length is associated with the specific type of bond between atoms in a molecule.
  • 28. Absorption of radiation depends on the wavelength of radiation
  • 29. • Energy of radiation is proportional to the frequency of radiation • the transfer of energy between the radiation and molecule results in a change in the wavelength of radiation
  • 30. Raman spectrography • Raman Spectrography uses the principle of "Raman Scattering" for CO2 measurement. • The gas sample is aspirated into an analyzing chamber, where the sample is illuminated by a high intensity monochromatic argon laser beam. • The light is absorbed by molecules which are then excited to unstable vibrational or rotational energy states (Raman scattering). • The Raman scattering signals (Raman light) are of low intensity and are measured at right angles to the laser beam. • The spectrum of Raman scattering lines can be used to identify all types of molecules in the gas phase
  • 33. Chemical method of CO2 measurement - pH sensitive chemical indicator
  • 34. Effect of atmospheric pressure • FEtCO2=partial pressure(atmospheric pressure-water vapour pressure)*100 • At atm pressure of 760mmHg, FEtCO2=38(760-47)*100 =5% at atm pressure of 500mmHg FEtCO2=38(500-47)*100 =8%
  • 35. Influence of water vapour 1. Effect of condensed water: Water vapor may condense on the window of the sensor cell and absorb IR light, thereby produce falsely high C02 readings
  • 36. 2. Effect of water vapor. The temperature of the sampling gases may decrease during the passage from the patient to the unit, resulting in a decrease in the partial pressure of water vapor. This can cause an apparent increase in C02 concentration of about 1.5-2% FEtCO2=partial pressure(atmospheric pressure-water vapour pressure)*100
  • 37. • History • Terminology • Why capnography • Basic physiology • Physics • Types • Components of capnography • Clinical application • Carry home
  • 38. Volume capnography Time capnography
  • 39. Time capnography Advantages • Simple and convenient • Monitor non-intubated patients • Monitor dynamics of inspiration and expiration Disadvantages • Poor estimation of V/Q status of lungs • Physiologic space dead space
  • 41. Side-stream Capnographs advantages Easy to connect No problems with sterilization Can be used in awake patients Easy to use when patient is in unusual positions such as in prone position Can be used in collaboration with simultaneous oxygen administration via a nasal prong disadvantages Delay in recording due to movement of gases from the ET to the unit Sampling tube obstruction Water vapor pressure changes affect CO2 concentrations Pressure drop along the sampling tube affects CO2 measurements
  • 42. Sampling of CO2 from nasal cannulae
  • 43. Adequacy of spontaneous respiration Sampling of CO2 from oxygen mask
  • 45. Mainstream • Advantages No sampling tube No obstruction No affect due to pressure drop No affect due to changes in water vapor pressure No pollution No deformity of capnograms due to non dispersion of gases No delay in recording Suitable for neonates and children • Disadvantages weight of the sensor, (the newer sensors are light weight minimizing traction on the endotracheal tube) Long electrical cord, but it is lightweight. Sensor windows may clog with secretions( they can be replaced easily as they are disposable) Difficult to use in unusual patient positioning such as in prone positions.
  • 46. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  • 47. Capnographic Waveform • Normal waveform of one respiratory cycle • Similar to ECG – Height shows amount of CO2 – Length depicts time
  • 48. 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
  • 49. Capnographic Waveform • Capnograph detects only CO2 from ventilation • No CO2 present during inspiration – Baseline is normally zero A B C D E Baseline
  • 50. Phase I Dead space ventillation Beginning of exhalation A B IBaseline
  • 51. Phase II Ascending Phase Alveoli CO2 present and increasing in exhaled air II A B C Ascending Phase Early Exhalation
  • 52. Phase III Alveolar Plateau CO2 exhalation wave plateaus A B C D III Alveolar Plateau
  • 53. Capnogram Phase III End-Tidal End of the the wave of exhalation contains the highest concentration of CO2 - number seen on monitor A B C D End-tidal
  • 54. Capnogram Phase IV Descending Phase • Inhalation begins • Oxygen fills airway • CO2 level quickly drops to zero Alveoli
  • 55. Capnogram Phase IV Descending Phase Inspiratory downstroke returns to baseline A B C D E IV Descending Phase Inhalation
  • 56. Inspiratory segment • Phase 0: Inspiration • Beta Angle - Angle between phase III and descending limb of inspiratory segment
  • 57. Expiratory segment • Phase I - Anatomical dead space • Phase II - Mixture of anatomical and alveolar dead space • Phase III - Alveolar plateau • Alfa angle - Angle between phase II and phase III (V/Q status of lung
  • 58. Capnography Waveform Normal range is 35-45mm Hg (5% vol) Normal Waveform 45 0
  • 59. Capnography Waveform Patterns 0 45 Hypoventilation RR : EtCO2 45 0 Hyperventilation RR : EtCO2 45 0 Normal
  • 60. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  • 61. Capnography-3 sources of information • No. – PEtCO2 values • Shapes of capnogram • (a-ET)PCO2 differences
  • 62. (a-ET)PCO2 differences • (a-ET)PCO2 difference is a gradient of alveolar dead space. increase decrease Age Emphysema Low cardiac output states Hypovolemia Pulmonary embolism Pregnancy and Children
  • 63. Five characteristics of capnogram should be evaluated The shape of a capnogram is identical in all humans with healthy lungs. Any deviations in shape must be investigated to determine a physiological or a pathological cause of the abnormality • Frequency • Rhythm • Height • Baseline • Shape
  • 65. • A terminal upswing at the end of phase 3, known as phase 4, can occur in pregnant subjects, obese subjects and low compliance states
  • 66. The slope the expiratory plateau is increased as a normal physiological variation in pregnancy
  • 67. Prolonged inspiratory descending limb • due to dispersion gases in the sampling line or as well as prolonged response time of the analyzer. Seen in children who have faster respiratory rates
  • 68. Base line elevated in • Inadequate fresh gas flow • Accidental administration of CO2 • Rebreathing • Insp / exp valve malfunction • Exhausted CO2 absorber
  • 70. Contamination of CO2 monitor • sudden elevation of base line and top line
  • 71. Expiratory valve malfunction • Expiratory valve malfunction can result in prolonged abnormal phase 2 and phase 0
  • 72. Inspiratory valve malfunction • Elevation of the base line, prolongation of down stroke, prolongation of phase III
  • 73. Bain circuit • Inspiratory base line and phase I are elevated above the zero due to rebreathing. Note the rebreathing wave during inspiration.
  • 74. Hypoventilation • Gradual elevation of the height of the capnogram, base line remaining at zero
  • 75. hyperventillation • Gradual decrease in the height of the capnogram, base line remaining at zero
  • 79. Cardiogenic oscillations. • Ripple effect, superimposed on the plateau and the descending limb, resulting from small gas movements produced by pulsations of the aorta and heart.
  • 80. Airway obstruction (eg., bronchospasm). Phase II and phase III are prolonged and alpha angle (angle between phase II and phase III) is increased
  • 84. hypothermia • A gradual decrease in end tidal carbon dioxide hypothermia, reduced metabolism, hyperventilation, leaks in the sampling system
  • 85. Kyphoscoliosis • The CO2 waveform has two humps. resulted in a compression of the right lung
  • 87. • Sampling problems such air or oxygen dilution during nasal or mask sampling of carbon dioxide in spontaneously breathing patients.
  • 88. Detection of pulmonary air embolism • A rapid decrease of PETCO2 in the absence of changes in blood pressure, central venous pressure and heart rate indicates an air embolism without systemic hemodynamic consequences. • as the size of air embolism increases, a reduction in cardiac output occurs which further decreases PETCO2 measurement. A reduced cardiac output by itself can decrease PETCO2.
  • 89. Effective circulating blood volume can reduce the height of capnograms
  • 90. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  • 91. Phases of the Capnogram Phase I Expiration Represents anatomical dead space Phase II Expiration Mixture of anatomical and alveolar dead space Phase III Expiration Plateau of alveolar expiration Phase 0 Inspiration Rapid fall in CO2 concentration Phase IV Exhalation Compromised thoracic compliance
  • 92. Hyperventilation Progressively lower plateau (phase II) segment Baseline remains at zero Decreasing CO2 levels
  • 93. Hypoventilation Steady increase in height of Phase II Baseline remains constant
  • 94. Spontaneous Ventilation Short Alveolar plateau Increased frequency of waveforms
  • 95. Cardiogenic Oscillations Ripples during Phase II and Phase III Due to changes in pulmonary blood volume and ultimately CO2 pressure as a result of cardiac contractions
  • 96. Curare Cleft Shallow dips in phase II plateau Can occur when patient is in a light plane of anesthesia Represent patient attempts to breathe independent of mechanical ventilation
  • 97. Bronchospasm Airway Obstruction COPD Sloping of inspiratory and expiratory segments Prolonged Phase II and Phase III
  • 98. Rebreathing of Soda Lime Contamination with CO2 Elevation of Phase II segment and baseline Elevation of baseline and Phase II, smaller inspiratory efforts Progressive elevation of Phase II and baseline
  • 99. Bain System Smaller wave form represents rebreathing of CO2
  • 100. Slow ventilation Incompetent inspiratory valve Prolongation of Phase 0
  • 102. • Capnography provides another objective data point in making a difficult decision