CAPNOGRAPHY

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CAPNOGRAPHY
Dr. Radhika Dhanpal radhika.dhanpal_at_rediffmail.c
om Professor and Head
Department of Anesthesiology and Critical
Care,St. Johns Medical College Hospital
Bangalore
Email anaesthesia.co.in_at_gmail.com
www.anaesthesia.co.in
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• ASA
• House of delegates July 1, 2011 implementation
  of Oct 2010 decision Standards for Basic
  Anesthesia MonitoringDuring 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

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• 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
  .

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• Terminology

Capnometer The machine
Capnography Wave form
Capnometry Numerical Valve
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• Methods of measurement
• Infrared spectrography
• Raman spectrography
• Mass spectrography
• Photoacoustic spectrography
• Chemical colorimetric analysis

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• 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.

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• 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 .

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

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• 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.

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

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• 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
  0.5 - 0.8 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.

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• 
  TYPES - I
• Side stream capnography
• A pump aspirates gas samples from the patients
  airway
• through a 6 foot long capillary tube into the
  main unit at a
• rate of 50-200 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.

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• 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

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• 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.

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

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• Time capnogram
• Inspiratory segment
• Expiratory segment
• Alpha angle
• Beta angle

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Phase I 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
a angle - 100-110º Airway Obstruction causes
larger angle. ß angle - 90º
Rebreathing increases the angle.

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Volume capnogram 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
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• Interpretation of the waveform
• Height
• Frequency
• Rhythm
• Baseline
• Shape

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PaCo2 PEtCo2-1 PaCo2 PEtCo2-1
Normal 2-5 mmHg Normal 2-5 mmHg
Increased Decreases
Age Large TV
Pulmonary disorders Low Frequency Ventilation
PE Pregnancy
CO Infants
Hypovolemia
Anaesthesia
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Metabolic PaCo2 PEtCo2-2 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 )
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PaCo2 PEtCo2-3 Circulatory PaCo2 PEtCo2-3 Circulatory
Increase Decrease
Epinephrine injection CO
CPR Surgical manipulations of the heart, great vessels, wedged PAC, PE Air Embolism
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• 
  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.

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• 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

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• REBREATHING WITH ELEVATED BASELINE

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• ESOPHAGEAL INTUBATION WITH CARBONATED BEVERAGES
  IN STOMACH

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• CO2 ABSORBENT EXHAUSTION

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• ESOPHAGEAL INTUBATION

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• ESOPHAGEAL INTUBATION FOLLOWING MASK
  VENTILATION.

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• EXPIRATORY VALVE MALFUNCTION

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• SPONTANEOUS BREATHING

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• NORMAL WAVEFORM

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• CURARE CLEFT

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• AIR LEAK

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• HYPERVENTILATION

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• CONTAMINATION OF
• CO2 SENSOR

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CARDIAC ARREST, SUCCESSFUL
RESUSCITATION
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• HYPOVENTILATION

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• BRONCHOSPASM

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• IMV WITH INTERPOSED SPONTANEOUS RESPIRATION.

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• CARDIOGENIC OSCILLATIONS (RIPPLE EFFECT)

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• INSPIRATORY VALVE
• MALFUNCTION

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• POST SINGLE LUNG TRANSPLANTATION.

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• BAIN CIRCUIT/MAPELSON D (SIGNATURE CAPNOGRAM)

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• Thank You

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