1. Email: anaesthesia.co.in@gmail.com
CAPNOGRAPHY
Dr. Radhika Dhanpal
Professor and Head
Department of Anesthesiology and Critical Care, St. John’s Medical College Hospital Bangalore

2. ASA
House of delegates July 1, 2011 implementation of Oct 2010 decision “Standards for Basic Anesthesia Monitoring”During regional anesthesia (with no sedation ) or local anesthesia (with no sedation ), the adequacy of ventilation shall be evaluated by continual observation of qualitative clinical signs. During moderate or deep sedation, the adequacy of ventilation shall be evaluated by continual observation of qualitative clinical signs and monitoring for the presence of exhaled CO2 unless precluded or invalidated by the nature of the patient, procedure or equipment”
ISA – Desirable standard 1999

3. Definition : Graphic display of instantaneous CO2
concentration
Luft
Collier
Ramwell
Holland in 1978 , was the first country to adopt it as a standard of monitoring during anaesthesia .

4. Terminology Capnometer The machine Capnography Wave form Capnometry
Numerical Valve

5. Methods of measurement
Infrared spectrography
Raman spectrography
Mass spectrography
Photoacoustic spectrography
Chemical colorimetric analysis

6. Raman spectrography
Gas sample is aspirated into the analysing chamber where it 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, these Raman scattering signals
are then measured.

7. Mass spectrography It separates gases and vapors of different molecular weight on the basis of their mass into a spectrum. By analyzing the spectrum, the composition and relative abundance of each gas in a sample can be determined .

8. Infrared method : Infrared waves at 4
Infrared method : Infrared waves at 4.3 mm are absorbed by certain gases producing absorption bands on the infrared electromagnetic spectrum.

9. Photoacoustic gas measurements The gas to be measured is irradiated by modulated light of a pre-selected wavelength . The light beam when chopped, generates an acoustic signal which is detected by two microphones.

10. Colorimetric method Chemically treated foam indicator attached to
endotracheal tube.

11. Factors influencing the reading ;
Atmospheric pressure : Changes in atmospheric pressure are usually of the order of 20 mm Hg . This results in a change in PaCO2 of less than mm Hg
PEEP .
Water vapour : Can condense on the sensor cell and produce falsely high readings. This may be prevented by
Heating sensor above body temperature
sampling tube can be made of a semipermeable polymer that allows water vapour to pass outside.
Absorbent filters.

12. TYPES - I
Side stream capnography
A pump aspirates gas samples from the patient’s airway
through a 6 foot long capillary tube into the main unit at a
rate of ml/min
Disadvantages
Children
Multiple sites for leaks and breakage
Delay
Scavenging needed
Advantages
Spontaneous breathing subjects
Patients on O2 nasal cannula
Easy to sterilise
Use in unusual positions.

13. TYPES –II Main stream capnography Disadvantages : Heavy Hot
Window to be kept clean
Advantages :
Faster
No gas is removed
No uncertainity by rate of gas sampling

14. Calibration :
Periodically
Gas of known CO2 concentration
Calibration cells with mixtures of CO2 and N2 are available.
Sampling tube should be the same type as the one used on the patient.

15. Type of capnogram Time capnogram Volume capnogram Fast 7mm/sec
Slow 0.7 mm/sec

16. Time capnogram Inspiratory segment Expiratory segment Alpha angle
Beta angle

17. Anatomical and apparatus dead space gas Phase II Rising CO2
No CO2
Anatomical and apparatus dead space gas
Phase II
Rising CO2
Mixing of dead space gas and alveolar gas.
Phase III
Static or rising CO2
Alveolar gas
Phase IV
Falling CO2
Beginning of inspiration
α angle º ; Airway Obstruction causes larger angle.
β angle - 90º ; Rebreathing increases the angle.

18. Volume capnogram
Advantage s
Volume of CO2 per exhaled
breath can be measured
Significant changes in the
morphology of the expired
wave form can be detected
Dead space can be
partitioned
Disadvantages
Intubation mandatory
Elaborate equipment
Only monitors expiration

19. Interpretation of the waveform
Height
Frequency
Rhythm
Baseline
Shape

20. PaCo2 – PEtCo2-1
Normal mmHg
Increased
Decreases
Age
Large TV
Pulmonary disorders
Low Frequency Ventilation PE
Pregnancy CO
Infants
Hypovolemia
Anaesthesia

21. Metabolic PaCo2 – PEtCo2-2 Increase Decrease Hyperpyrexia Hypothermia
Shivering
Increased Muscle relaxation
Convulsions
Blood /NaHCO3 administration
Release of an arterial clamp/tourniquet
Dextrose containing fluids
Parenteral hyperailmentation
CO2 insufflation ( peritoneum , Pleura , joint )

22. PaCo2 – PEtCo2-3
Circulatory
Increase
Decrease
Epinephrine injection CO
CPR
Surgical manipulations
of the heart, great vessels,
wedged PAC, PE
Air Embolism

23. Uses
Anaesthesia
Verification of tracheal intubation
Assist in blind oral or nasal intubation
Needle cricothyroidotomy
Jet stylet introducer
Fiberoptic bronchoscopy
Double lumen tube placement
Monitoring of spontaneous ventilation
Curare cleft
HFJV
Detection of circuit leaks
Detection of malfunction of valves or faulty anaesthetic system.

24. Critical Care
CPCR
Determine the needs during mechanical ventilation
Weaning
Placement of NG tube
Others
PACU
Patient transfer
Post operative ward
Procedural sedation
Apnea test for brain death
Emergency Department

27. REBREATHING WITH ELEVATED BASELINE

29. ESOPHAGEAL INTUBATION WITH CARBONATED BEVERAGES IN STOMACH

31. CO2 ABSORBENT EXHAUSTION

33. ESOPHAGEAL INTUBATION

35. ESOPHAGEAL INTUBATION FOLLOWING MASK VENTILATION.

37. EXPIRATORY VALVE MALFUNCTION

39. SPONTANEOUS BREATHING

41. NORMAL WAVEFORM

43. CURARE CLEFT

45. AIR LEAK

47. HYPERVENTILATION

49. CONTAMINATION OF CO2 SENSOR

51. SUCCESSFUL RESUSCITATION
CARDIAC ARREST,
SUCCESSFUL RESUSCITATION

53. HYPOVENTILATION

55. BRONCHOSPASM

57. IMV WITH INTERPOSED SPONTANEOUS RESPIRATION.

59. CARDIOGENIC OSCILLATIONS (RIPPLE EFFECT)

61. INSPIRATORY VALVE
MALFUNCTION

63. POST SINGLE LUNG TRANSPLANTATION.

65. BAIN CIRCUIT/MAPELSON D (SIGNATURE CAPNOGRAM)

67. Email: anaesthesia.co.in@gmail.com
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