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Capnography
- 1. CAPNOGRAPHY DR. PRIYANKA
- 2. CAPNOGRAPHY • Measurment of CO2 in respiratory gases. • Integral part of anesthesia monitoring. • Luft 1943 developed it from knowledge that co2 is absorbs infrared radiation of particular wavelength. • Collier – value of rapid IR CO2 analysis • Value of end tidal sample – Ramwell • 1978 Holland – first country to adopt capnography as standard monitoring in anesthesia
- 3. GUIDELINES • ASA included capnography in its standrads for basic monitoring. • ISA designated it as ‘desirable’ monitor in anesthesia. • ISA – “Anesthesia monitoring standards recommended in India” for basic monitering from 1999.
- 4. Terminology • Capnography: display of instanteneous CO2 conc. Vs time (time capnogran) or expired volume (volume capnogram) • Capnograph: Machine that generates waveform. • Capnogram: Actual waveform
- 5. Terminology • Capnometry: Measurment & numerical display • Capnometer: Device that performs the measurement & display readings • Breath to breath waveform needs to be displayed for continuous monitoring
- 6. Methods used for measurement • Raman spectometry – scatering • Gas sample is illuminated by high intensity monochromatic Argon laser beam. • Light is absorbed by molecules which is then excited to unstable vibrational & rotational energy states, called as ‘Raman scattering’ • Used to identify molecules in gas phase including CO2 & inhalational agents
- 7. Methods used for measurement • Mass spectrometry • Photoacoustic gas measurement • Colorimetric method
- 8. Types of capnograph SIDE STREAM MAIN STREAM
- 9. TYPES OF CAPNOGRAPH SIDE STREAM MAIN STREAM • CO2 sensor located in main • Cuvette containing CO2 sensor monitor inserted between breathing • Tiny pump aspirates gas from circuit & ETT. patients airway • IR rays detector • Transferred by 6 ft long • No need of sampling & capillary tube in to main unit scavenging. • Rate 50 – 200 ml/min • To prevent condensation of • Contamination of FGF water vapour, heated to 40°C • Water trap • Skin burns • Gas should be retrieved & • Kinking of tube reinjected • False reading if not clean • Spontaneous respiration • Better in children
- 11. CALIBRATION • Capnographs must be calibrated periodically • At least daily acc to manufacturers for main stream • Automatic Zeroing – side stream moniter • Main stream calibration sample cell sealed with mixtures of CO2 & N2 • Range is up to 100mmHg which is useful in rare cases like malignant hyperthermia, hypoventilation.
- 12. NORMAL CAPNOGRAM
- 13. NORMAL TIME CAPNOGRAM I II III IV
- 14. PHYSIOLOGY • EXPIRATION • PHASE I – Dead space gas exaled, no CO2 • PHASE II – Mixing of alveolar gas with dead space • PHASE III - Alveolar Plateau, CO2 reach • INSPIRATION • PHASE IV – Inspiration starts CO2 becomes zero • α angle – PHASE II & PHASE III 1OO° V/Q • β angle – PHASE III & PHASE IV 90° REBREATHING
- 17. VOLUME CAPNOGRM
- 18. TYPE OF CAPNOGRAMS TIME CAPNOGRAM VOLUME CAPNOGRAM
- 19. CLINICAL USES • NORMAL VALUE: 35 – 45 mmHg • Metabolism • Increased with increase in metabolism • Increased temp, shivering, convulsions,excess catecholamine, blood & bicabonate administration, release of torniquet with reperfusion, glucose containing iv fluids • Laproscopy, thoracoscopy.
- 20. How to interpret capnogram? • Respiratory Rate (speed of paper to be known) • Height of capnogram ( value of max exp & inspiratory conc of CO2) • Shape ( altered in abnormal states) • Baseline of capnogram (rebreathing)
- 21. 13 HYPERMETABOLISM
- 22. 16 MALIGNANT HYPERTHERMIA
- 23. HYPOTHERMIA
- 24. 5 REBREATHING
- 25. 4 REBREATHING
- 26. 1 REBREATHING
- 28. CIRCULATION • Reduced with reduction in cardiac output if ventilation is normal. • Reduced blood flow to lungs reduces as in thoracic surgery, manipulation to heart. • Rapid reduction in ETCO2 in absence of changes in BP, HR, CVP indicates pulmonary embolism. • Large embolism - reduce CO further reduction in CO2
- 30. STEADY STATE
- 31. AIR EMBOLISM
- 33. 18 CARDIAC OSSILATION Cardiac pulsations transmitted to vessels to lungs
- 34. RESPIRATORY • Intubation verification • Blind nasal intubation • Awake fiberoptic intubation • Cricothyroidectomy • Jet ventilation • Double lumen tube • Monitoring of respiratory rate • Partial airway obstruction
- 35. HYPOVENTILATION Gradual increase in CO2 with 0 baseline
- 36. 3 BRONCHOSPASM Increased α angle, obstruction to expiration
- 38. 10 OESOPHAGEAL INTUBATION Carbonated products in stomach
- 39. DVT & PULMONARY EMBOLISM
- 40. KHYPHOSCOLIOSIS
- 41. Anesthesia • Disconnection • Partial paralysis • Minute ventilation • Circuit leak • Total occlusion • In partial rebreathing circuit & low flow anesthesia
- 42. 11 DISCONNECTION Sudden fall to zero
- 43. 6 CURARE CLEFT cleft in phase III due to spontaneous breath
- 44. SPONTANEOUS BREATHS IN BETWEEN Shape change of spontaneous & mechanical ventilation
- 46. INSPIRATORY VALVE NOT CLOSED
- 47. EXPIRTORY VALVE DYSFUNCTION • Expiratory valve stuck • Increased inspiratory co2
- 48. PROMBLEMS IN SAMPLE LINE LOW SAMPLING RATE CONTAMINATION BY FGF
- 49. AIR DILUTION FGF
- 50. LEAK IN SAMPLE LINE WITH IPPV
- 52. NON STEADY STATE
- 53. LMA & ETT
- 54. TAKE HOME MESSAGES • Capnography included as standard of basic monitoring. • Side stream & main stream advantages & disadvantages. • Helpful in monitoring of respiratory rate, ETCO2, rebreathing, prediction of PaCO2 • Shapes of capnogram help in diagnosis of abnormal conditions. • Must be calibrated periodically. • Must be cleaned or disposed to prevent cross infection.
- 55. THANK YOU