Capnography in icu

1. Capnography

3. Luft developed the principle of capnography
in 1943 from the knowledge that CO2 is
one of the gases that absorbs infra-red (IR)
radiation of
a particular wavelength.

4. In 1978 Holland
was the first
country to adopt capnography
as a standard of monitoring

5. Capnography, has become an integral part
of monitoring for preventing life
threatening events

6. Incidence of hypoxia is less
Capnography when used in conjunction
with pulse oximetry and visual inspection
of chest
detected respiratory depression 17 times
more often than without capnography

7. •Capnography forewarns of
impending hypoxia by about 5 to 240
seconds
Capnography triggers early
intervention and decreases the
incidence of oxygen desaturation

8. Monitors
use
infrared spectrography
mass spectrography
Raman spectrography
photoacoustic analysers
colorimetric devices

9. Hypoxia is our
primary concern
If
uncorrected
can lead to
death

10. Applications of Capnography

11. INTENSIVIST

12. Capnography
A graphic display of instantaneous CO2
concentration (FCO2) versus time or expired
volume during a respiratory cycle
(CO2 waveform or capnogram)

13. Machine that generates a waveform and
the capnogram is the actual waveform
Capnograph
Capnometer

14. Numerical display of maximum inspiratory and
expiratory CO2
concentrations during a respiratory cycle
Capnometry

15. Capnograms
CO2 waveforms which can be of two types
CO2 expirogram
Time capnogram

16. Infra Red Spectrography
CO2 absorbs Infra red light at 4.3
µm

17. Factors affecting IR
Spectrography
Effect of Atmospheric Pressure

18. • Use of 4.3 µ m IR light does not
affect CO2 measurements
Effect of N2O on CO2
measurements

19. Effect of N2O on CO2
measurements

20. Effect of Oxygen on CO2
measurements

21. Effect of water vapor
Water absorbs IR light but minimum at 4.3µ m

22. Changes in water vapor alter CO2
readings

23. Water can obstruct sampling tube

24. Methods for decreasing contamination of
sampling tubes by liquids or secretions
Position the sampling
vertically upwards
Use water filters at both
ends of sampling tube

25. Response Time of Analyzer
Slow analyzers distort CO2 wave forms

26. Use of more powerful amplifiers
Minimizing the volume of the sampling
chamber and tubes
Use of relatively high sampling flow rates
(150 ml-min-l)
Response time can be reduced by

27. Inhalational agents do not affect
CO2 measurement

28. Chemical method of CO2
measurement
A chemically
treated foam
indicator
contained in a
plastic container

29. MAIN STREAM CAPNOGRAPH SIDE STREAM CAPNOGRAPH
Types of Capnographs

30. Time Capnogram
Volume Capnogram

31. Time Capnogram
Volume Capnogram
No inspiratory segment in a volume capnogram.
Time capnogram has both inspiratory (0) as well as
expiratory segment.
The expiratory segment of a volume capnogram is divided
into three phases, phase I, II, and III

32. • Normal end expiratory CO2
partial pressure ranges between
35 and 45 mmHg

33. BASIC PHYSIOLOGY

34. Fast Capnogram
A Trend Capnogram

35. A time capnogram may be recorded at
two speeds
High speed capnogram (7mm.sec-1)
Detailed information about each breath
Overall CO2 changes (trend) can be
followed at a slow (0.7 mm.sec-1) speed

36. Fast or regular capnogram

37. Trend Capnogram

38. Components of a time capnogram
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)

39. Nearly 90
During rebreathing
beta angle increases
the horizontal baseline of phase 0
and phase I can be elevated above
normal
Beta Angle

40. Prolonged response time of the
capnometer compared to
respiratory cycle time of the
patient, particularly in children,
can give same picture

41. Between phases 11 and III
Increases as the slope of phase 111 increases
the angle.
The alpha angle (primarily linked to variations in
time constants within the lung)
An indirect indication of V/Q status of the lung
Alpha Angle

42. Alveolar Plateau (phase III) has positive slope
due to Continuous excretion of CO2 from Late
emptying of alveoli with low V/Q ratio
containing relatively higher CO2 concentration
Alveolar Plateau

43. Lower part of the
lung is also better
perfused
Lower part of the
lung is better
ventilated

45. If a low V/Q contaninig high CO2 have long time
constant, they will contribute to late part of
phase III leadig to positive deflection of that
phase

46. Positive slope of phase III
due to late emptying of low v/Q alveoli that
contain high CO2.
alpha angle is an indirect incication of V/Q
status of the lungs

47. Simple and convenient
Monitor non-intubated patients
Monitors dynamics of inspiration as well
as expiration
Advantages of time capnography

48. Poor estimation of V/Q status of the lung
Can not be used to estimate components
of physiological deadspace
Disadvantages of time capnography

49. Components of the tidal volume with
capnograph

50. Increased (a-ET)PCO2
COPD
OLD AGE
Hypovolemia
Pulmonary embolism

51. (a-ET)PCO2 decreases
Low frequency ventilation
High tidal volume
Children
Pregnant ladies

52. Decreased COP will increase alveolar
dead space and increase
(a-ET)PCO2

53. How is a capnogram related to a tidal
volume

54. Determination of components of tidal
volume using a capnogram
Physiological dead space
sub-divided into anatomical and alveolar dead space

55. Ventilation/perfusion in thelungs

56. Any factor that affects V/Q ratio can
affects the slope and the height of
phase III
CARDIAC OUTPUT
FUNCTIONAL RESIDUAL CAPACITY
CO2 PRODUCTION
AIRWAY RESISTANCE
Ventilation/perfusion in the lungs

57. Cardiac output and capnograms

58. Encyclopedia of capnograms

59. Normal Capnogram

60. Capnogram recorded during general
anesthesia for cesarean section
The slope of the phase III is increased. This is a normal physiological variation.
Airway obstruction can result in an increase in the phase III as well.

61. Depending on the severity of airway
obstruction, phase II can also be prolonged
Occasionally, a phase IV can also occur in
pregnant subjects

62. Capnogram with increased
phase III slope
Capnogram with
phase IV
Capnograms in pregnancy

63. Airway
obtruction /
Bronchospasm
Phase II and phase III are
prolonged

64. Most commonly seen
capnograms

65. Spontaneous ventilation
Short alveolar plateau

66. Hyperventilationon
Baseline at zero,
but height is reduced gradually

67. Hypoventilation
Base line at zero, but height is
increased gradually

68. IMV ventilation
IMV breaths interposed with
spontaneous ventilation

69. Apnea
Self explanatory
Apnea, or Respiratory obstruction
A flat line indicates that there is apnea, or total respiratory
obstruction.
It may also indicate disconnection of the CO2 sampling system,
or inability to sample the expired air

70. Ripples on the alveolar
plateau and
descending limb due
to movement of gas in
the airway as a result
of cardiogenic
oscillations
Ripple effect
Cardiogenic Oscillations

71. Curare Cleft

72. Rebreathing capnograms

73. Exhausted Soda lime
• Gradual elevation of baseline and the height
of the capnograms

74. Hyperventilation
• Baseline is elevated,
• but height can remain the same due to
hyperventilation

75. Rebreathing
• Baseline is elevated, there is an inspiratory
wave due to rebreathing of CO2, the height
of the capnogram is gradually increasing.

76. Inspiratory valve defects
• The inspiratory valve is not closing properly
resulting in a flip in the plateau at the beginning of
inspiration.

77. Inspiratory valve malfunction
• valve displaced or totally
incompetent

78. Plateau is prolonged due to rebreathing

79. Expiratory valve defects
• Prolonged phase II, slanting of descending
limb of inspiration, baseline elevation

80. Malignant Hyperpyrexia
• The height of the capnograms is increased. Baseline
at zero until soda lime exhaustion.

81. Hypotherm
• Hypothermia/reduced
metabolism
• The height of the
capnograms is decreased.

82. Sampling leaks
• Sampling tube leaks, Sampling via oxygen face mask,
nasal cannula

83. Break in the sampling tube system or loose
connections at sampling tube end of the monitor
Sampling leaks

84. • Breakage in the sampling filter
• Dual plateau capnogram
Sampling leaks

85. Partial disconnection of main stream sensor (like
curare cleft)

86. Contamination of CO2 sensor
• Sudden rise of base line and height of the
waveform

87. Esophageal intubation
• Flat line as no carbon dioxide

88. Presence of CO2 in the stomach can give rise to
fluctuations in the base line

89. • Occasionally enough alveolar gas can be forced
down the esophagus into the stomach during
mask ventilation resulting transiently in few
capnograms as below
Esophageal intubation

90. • Carbonated beverages in the stomach can
result in significant CO2 in expired gases
during six breaths.
• However, the shape of capnograms should
alert to a non tracheal intubation.
Esophageal intubation

91. Biphasic capnogram
Lung transplant
• Biphasic capnogram following single lung
transplant suggesting characteristic differential
emptying of each lung

92. Biphasic capnogram
kyphoscoliosis
• Biphasic capnogram in a patient with severe
kyphoscoliosis.
• Differential emptying of lungs

93. Endobronchial intubation
Biphasic capnogram
• Biphasic capnogram as
a result of endotracheal
tube in right main
bronchus
Endotracheal tube pulled
back above tracheal carina

94. Downward sloping phase III
• The slope of phase III can be reversed in
patients with emphysema where there is
marked destruction of alveolar capillary
membranes and reduced gas exchange

95. CARDIAC ARREST

96. Air Embolism

97. Thrombo Embolism

98. Capnography during laparoscopic
surgery
Adjust ventilation
Detection of accidental
intravascular CO2 insufflation
Detection of pneumothorax, and
hemorrhage

99. Hemodynamic and ventilatory changes during
CO2 insufflation

100. Carbon dioxide Embolism

101. Capnography
• Five characteristics should be inspected:
height, frequency, rhythm,
baseline, and shape

102. Metabolism
• An increase in end-tidal CO2 is a reliable
indicator of increased metabolism
• only in mechanically ventilated patients
• In spontaneously breathing patients, PET CO2
may not increase as a result of
hyperventilation

103. Increased temperature
Shivering
Convulsions
Excessive production of
catecholamines
Administration of blood or
bicarbonate
Release of an arterial clamp or
tourniquet with reperfusion
of ischaemic areas
Glucose in the intravenous
fluid
Parenteral hyperalimentation
CO2 used to inflate the
peritoneal cavity during
laparoscopy, the pleural
cavity during thoracoscopy
or a joint during
arthroscopy.
Metabolic causes of increases in expired CO2
include

104. Malignant hyperthermia
Hypermetabolic state
Massive increase in CO2
production
before the rise in temperature
• Early detection through
monitoring CO2

105. Malignant hyperthermia
• Capnography can be monitored for the
effectiveness of treatment.
• CO2 production falls with decreased
temperature, increased muscle relaxation, and
increased depth of anaesthesia.

106. During good CPR
{ 10 – 15 mmHg }
if you keep PETCO2 up in that 25
range
then there's circulation still going
on. ...
That's where you're going to get a
positive outcome

107. Capnograms during spontaneous ventilation
When oxygen is being administered via face mask can
be different due to dilution of expired CO2 by oxygen
or room air

108. COPD
V/Q perfusion abnormalities
result in a sloping phase II and
phase III

109. Capnograms during Conscious sedation in
spontaneous ventilation
Look for three important changes from baseline
capnograms
•Respiratory rate
A decreased rate indicates respiratory
depression.
Increased rate suggests stimulation from the
procedure

110. If the PETCO2 increases, it suggests
hypoventilation
If the PETCO2 decreases, it suggests
hyperventilation, hypoventilation, or upper
airway obstruction depending on the cause.
Observe the patient carefully for evidence of
respiratory obstruction.
If present, give jaw thrust, PETCO2 increases as
obstruction is relieved.

111. If there is no improvement in PETCO2,
it most likely suggests a central
depression.
Hyperventilation is indicated by an
increased respiratory rate.

112. Over sedation
Height of the capnogram
PETCO2 decreased

113. Hypoventilation
Height of the capnogram
(PETCO2) is increased

115. VENTILATOR CIRCUIT
CO2 can highlight derangement in each
circuit

116. Raman
spectrography
infrared
Spectrography
Methods to measure CO2 level
Photoacoustic
spectrography
Mass spectrography
Chemical colorimetric
analysis.

117. • Capnogram recorded during the
use of Bain anesthetic system / Mapelson D.
• The base line is elevated from zero.
• During inspiration, there a small rebreathing wave
due to inhalation of carbon dioxide.
• The extent of CO2 rebreathing depends FGF, tidal
volume, and respiratory frequency.
• Red indicates inspiration.

118. • A similar capnogram has been reported during
closed circuit anesthesia and IPPV where soda
lime was totally exhausted

119. • The only difference observed between the two
capnograms is that the signature wave during
inspiration in the case of exhausted CO2 absorbent
is closer to the expiratory waveform than that
during bain circuit

121. • Curare cleft capnogram (if the second peak occurred
during expiration)
Rebreathing capnogram (if the second peak occurred
during inspiration).
• Capnographs do not have a device yet for marking
inspiration and expiration on the time capnogram,
thereby delaying the diagnosis of the problem.