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CAPNOGRAPHY
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical appl...
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical appl...
• 1943- luft –CO2 absorbs infrared light
• Ramwell – proved it beyond doubt
• 1978- holland the first country to adopt
• 1...
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical appl...
terminology
• Capnometry
• Capnometer
• Capnography
• Capnogram
• Capnograph
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical appl...
Oxygenation
• Measured by pulse oximetry (SpO2)
– Noninvasive measurement
– Percentage of oxygen in red blood cells
– Chan...
• Capnography provides information about
CO2 production, pulmonary perfusion,
alveolar ventilation, respiratory patterns,
...
Ventilation
• Measured by the end-tidal CO2
– Partial pressure (mmHg) or volume (% vol) of
CO2 in the airway at the end of...
Oxygenation and Ventilation
• Oxygenation
– Oxygen for
metabolism
– SpO2 measures
% of O2 in RBC
– Reflects change in
oxyg...
Why Capnography ?
• Capnography, an indirect monitor
helps in the differential diagnosis of hypoxia
to enable remedial mea...
• Capnography and pulse oximetry together
could have helped in the prevention of
93% of avoidable anesthesia mishaps
accor...
Case Scenario
• 61 year old male
• C/O: ―short-of-breath‖ and ―exhausted‖
• H/O: > 45 years of smoking 2 packs a day,
3 he...
Why Measure Ventilation—
Non-Intubated Patients
• Objectively assess acute
respiratory disorders
– Asthma
– COPD
• Possibl...
Why Measure Ventilation—
Non-intubated Patients
• Gauge severity of hypoventilation states
– Drug intoxication
– Congestiv...
• History
• Terminology
• Why capnography
• Basic physiology
• Physics
• Types
• Components of capnography
• Clinical appl...
CO2 transport
• 60% as bicarbonate ion
• 10-20% binds to amino group of proteins
mostly hemoglobin
HALDANE EFFECT
• 5-10% ...
End-tidal CO2 (EtCO2)
r r Oxygen
O
2
CO2
O
2
VeinA te y
Ventilation
Perfusion
Pulmonary Blood Flow
Right
Ventricle
Left
At...
End-tidal CO2 (EtCO2)
• Carbon dioxide can be measured
• Arterial blood gas is PaCO2
– Normal range: 35-45mmHg
• Mixed ven...
End-tidal CO2 (EtCO2)
• Reflects changes in
– Ventilation - movement of air in and
out of the lungs
– Diffusion - exchange...
End-tidal CO2 (EtCO2)
• Monitors changes in
– Ventilation - asthma, COPD, airway
edema, foreign body, stroke
– Diffusion -...
a-A Gradient
r r Alveolus
PaCO2
VeinA te y
Ventilation
Perfusion
Arterial to Alveolar Difference for CO2
Right
Ventricle
L...
End-tidal CO2 (EtCO2)
• Normal a-A gradient
– 2-5mmHg difference between the EtCO2
and PaCO2 in a patient with healthy lun...
Negative a-A gradient
• Pregnancy
• Infants and children
• During and after bypass
• after coming of cardiac bypass
• Low ...
• History
• Terminology
• Why capnography
• Basic physiology
• Physics
• Types
• Components of capnography
• Clinical appl...
Raman effect
• Electromagnetic radiation and molecule
• The transfer of energy affects the vibration
energy associated wit...
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 mol...
Raman spectrography
• Raman Spectrography uses the principle of "Raman
Scattering" for CO2 measurement.
• The gas sample i...
Mass spectrograpy
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...
Influence of water vapour
1. Effect of condensed water:
Water vapor may condense on the
window of the sensor cell and abso...
2. Effect of water vapor.
The temperature of the sampling gases
may decrease during the passage from the
patient to the un...
• History
• Terminology
• Why capnography
• Basic physiology
• Physics
• Types
• Components of capnography
• Clinical appl...
Volume capnography Time capnography
Time capnography
Advantages
• Simple and convenient
• Monitor non-intubated patients
• Monitor dynamics of inspiration and...
Sidestream
Side-stream Capnographs
advantages
Easy to connect
No problems with sterilization
Can be used in awake patients
Easy to us...
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
v...
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical appl...
Capnographic Waveform
• Normal waveform of one respiratory cycle
• Similar to ECG
– Height shows amount of CO2
– Length de...
Capnographic Waveform
• Waveforms on screen and printout
may differ in duration
– On-screen capnography waveform is
conden...
Capnographic Waveform
• Capnograph detects only CO2
from ventilation
• No CO2 present during inspiration
– Baseline is nor...
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...
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
segme...
Expiratory segment
• Phase I - Anatomical
dead space
• Phase II - Mixture of
anatomical and
alveolar dead space
• Phase II...
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 appl...
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 c...
Five characteristics of capnogram
should be evaluated
The shape of a capnogram is identical in all
humans with healthy lun...
Resuscitation- trend
• A terminal upswing
at the end of phase
3, known as phase
4, can occur in
pregnant subjects,
obese subjects
and low
compl...
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...
Base line elevated in
• Inadequate fresh gas flow
• Accidental administration of CO2
• Rebreathing
• Insp / exp valve malf...
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...
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
Cardiogenic oscillations.
• Ripple effect,
superimposed on
the plateau and the
descending limb,
resulting from
small gas
m...
Airway obstruction (eg., bronchospasm). Phase II and phase III
are prolonged and alpha angle (angle between phase II and
p...
bronchospasm
during After relief
Curare effect
Malignant hyperpyrexia
hypothermia
• A gradual decrease in
end tidal carbon
dioxide
hypothermia,
reduced metabolism,
hyperventilation,
leaks in t...
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...
Detection of pulmonary air embolism
• A rapid decrease of PETCO2
in the absence of changes in
blood pressure, central
veno...
Effective circulating blood volume can
reduce the height of capnograms
• History
• Terminology
• Why capnography
• Physics
• Types
• Basic physiology
• Components of capnography
• Clinical appl...
Phases of the Capnogram
Phase I
Expiration
Represents
anatomical
dead space
Phase II
Expiration
Mixture of
anatomical and
...
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...
Curare Cleft
Shallow dips in phase II plateau
Can occur when patient is in a light plane of
anesthesia
Represent patient a...
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...
Bain System
Smaller wave form represents rebreathing of CO2
Slow ventilation
Incompetent inspiratory valve
Prolongation of Phase 0
• Capnography provides
another objective data
point in making a
difficult decision
Capnography
Capnography
Capnography
Capnography
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Capnography

  1. 1. CAPNOGRAPHY
  2. 2. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  3. 3. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  4. 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. 5. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  6. 6. terminology • Capnometry • Capnometer • Capnography • Capnogram • Capnograph
  7. 7. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  8. 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. 9. • Capnography provides information about CO2 production, pulmonary perfusion, alveolar ventilation, respiratory patterns, and elimination of CO2 from the anesthesia circuit and ventilator.
  10. 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. 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. 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. 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. 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. 15. Why Measure Ventilation— Non-Intubated Patients • Objectively assess acute respiratory disorders – Asthma – COPD • Possibly gauge response to treatment
  16. 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. 17. • History • Terminology • Why capnography • Basic physiology • Physics • Types • Components of capnography • Clinical application • Carry home
  18. 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. 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. 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. 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. 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. 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. 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. 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. 26. • History • Terminology • Why capnography • Basic physiology • Physics • Types • Components of capnography • Clinical application • Carry home
  27. 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. 28. Absorption of radiation depends on the wavelength of radiation
  29. 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. 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
  31. 31. Mass spectrograpy
  32. 32. Chemical method of CO2 measurement - pH sensitive chemical indicator
  33. 33. 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%
  34. 34. 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
  35. 35. 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
  36. 36. • History • Terminology • Why capnography • Basic physiology • Physics • Types • Components of capnography • Clinical application • Carry home
  37. 37. Volume capnography Time capnography
  38. 38. 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
  39. 39. Sidestream
  40. 40. 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
  41. 41. Sampling of CO2 from nasal cannulae
  42. 42. Adequacy of spontaneous respiration Sampling of CO2 from oxygen mask
  43. 43. mainstream
  44. 44. 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.
  45. 45. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  46. 46. Capnographic Waveform • Normal waveform of one respiratory cycle • Similar to ECG – Height shows amount of CO2 – Length depicts time
  47. 47. 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
  48. 48. Capnographic Waveform • Capnograph detects only CO2 from ventilation • No CO2 present during inspiration – Baseline is normally zero A B C D E Baseline
  49. 49. Phase I Dead space ventillation Beginning of exhalation A B IBaseline
  50. 50. Phase II Ascending Phase Alveoli CO2 present and increasing in exhaled air II A B C Ascending Phase Early Exhalation
  51. 51. Phase III Alveolar Plateau CO2 exhalation wave plateaus A B C D III Alveolar Plateau
  52. 52. 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
  53. 53. Capnogram Phase IV Descending Phase • Inhalation begins • Oxygen fills airway • CO2 level quickly drops to zero Alveoli
  54. 54. Capnogram Phase IV Descending Phase Inspiratory downstroke returns to baseline A B C D E IV Descending Phase Inhalation
  55. 55. Inspiratory segment • Phase 0: Inspiration • Beta Angle - Angle between phase III and descending limb of inspiratory segment
  56. 56. 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
  57. 57. Capnography Waveform Normal range is 35-45mm Hg (5% vol) Normal Waveform 45 0
  58. 58. Capnography Waveform Patterns 0 45 Hypoventilation RR : EtCO2 45 0 Hyperventilation RR : EtCO2 45 0 Normal
  59. 59. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  60. 60. Capnography-3 sources of information • No. – PEtCO2 values • Shapes of capnogram • (a-ET)PCO2 differences
  61. 61. (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
  62. 62. 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
  63. 63. Resuscitation- trend
  64. 64. • A terminal upswing at the end of phase 3, known as phase 4, can occur in pregnant subjects, obese subjects and low compliance states
  65. 65. The slope the expiratory plateau is increased as a normal physiological variation in pregnancy
  66. 66. 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
  67. 67. Base line elevated in • Inadequate fresh gas flow • Accidental administration of CO2 • Rebreathing • Insp / exp valve malfunction • Exhausted CO2 absorber
  68. 68. Elevation of base line
  69. 69. Contamination of CO2 monitor • sudden elevation of base line and top line
  70. 70. Expiratory valve malfunction • Expiratory valve malfunction can result in prolonged abnormal phase 2 and phase 0
  71. 71. Inspiratory valve malfunction • Elevation of the base line, prolongation of down stroke, prolongation of phase III
  72. 72. Bain circuit • Inspiratory base line and phase I are elevated above the zero due to rebreathing. Note the rebreathing wave during inspiration.
  73. 73. Hypoventilation • Gradual elevation of the height of the capnogram, base line remaining at zero
  74. 74. hyperventillation • Gradual decrease in the height of the capnogram, base line remaining at zero
  75. 75. Oesophageal intubation
  76. 76. 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.
  77. 77. Airway obstruction (eg., bronchospasm). Phase II and phase III are prolonged and alpha angle (angle between phase II and phase III) is increased
  78. 78. bronchospasm during After relief
  79. 79. Curare effect
  80. 80. Malignant hyperpyrexia
  81. 81. hypothermia • A gradual decrease in end tidal carbon dioxide hypothermia, reduced metabolism, hyperventilation, leaks in the sampling system
  82. 82. Kyphoscoliosis • The CO2 waveform has two humps. resulted in a compression of the right lung
  83. 83. • Capnogram during spontaneous ventilation in adults
  84. 84. • Sampling problems such air or oxygen dilution during nasal or mask sampling of carbon dioxide in spontaneously breathing patients.
  85. 85. 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.
  86. 86. Effective circulating blood volume can reduce the height of capnograms
  87. 87. • History • Terminology • Why capnography • Physics • Types • Basic physiology • Components of capnography • Clinical application • Carry home
  88. 88. 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
  89. 89. Hyperventilation Progressively lower plateau (phase II) segment Baseline remains at zero Decreasing CO2 levels
  90. 90. Hypoventilation Steady increase in height of Phase II Baseline remains constant
  91. 91. Spontaneous Ventilation Short Alveolar plateau Increased frequency of waveforms
  92. 92. 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
  93. 93. 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
  94. 94. Bronchospasm Airway Obstruction COPD Sloping of inspiratory and expiratory segments Prolonged Phase II and Phase III
  95. 95. 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
  96. 96. Bain System Smaller wave form represents rebreathing of CO2
  97. 97. Slow ventilation Incompetent inspiratory valve Prolongation of Phase 0
  98. 98. • Capnography provides another objective data point in making a difficult decision

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