End tidal co2 and transcutaneous monitoring

End tidal co2 and transcutaneous carbon dioxide monitors

1. 1.End tidal carbon dioxide analysis 2.Transcutaneous and carbon dioxide monitors

2. Introduction Capnometry refers to the measurement and quantification of inhaled or exhaled CO 2 concentrations at the airway opening. Capnograph y , however, refers not only to the method of CO 2 measurement, but also to its graphic display as a function of time or volume.

3. PHYSIOLOGY OF CAPNOMETRY

4. Oxygenation and Ventilation Oxygenation (oximetry ) Cellular Metabolism Ventilation ( capnography ) CO 2 O 2

5. Oxygenation and Ventilation Oxygenation Oxygen for metabolism SpO 2 measures % of O 2 in RBC Reflects change in oxygenation within 5 minutes Ventilation Carbon dioxide from metabolism EtCO 2 measures exhaled CO 2 at point of exit Reflects change in ventilation within 10 seconds

6. CO 2 transport

7. End-tidal CO 2 (EtCO 2 ) 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

8. End-tidal CO 2 (EtCO 2 ) r r O x y g e n O 2 C O 2 O 2 V e i n A t e y Ventilation Perfusion Pulmonary Blood Flow Right Ventricle Left Atrium

9. End-tidal CO 2 (EtCO 2 ) 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

10. Principles of capnography

11. BEER-LAMBERT LAW

12. Types of sensors Solid state CO2 sensors Chopper wheel CO 2 sensor

13. Sidestream vs Mainstream Capnometry Sidestream / Diverging CO 2 sensor located away from the airway gases to be measured. Incorporate a pump or compressor. Tubing length- 6 ft Gas withdrawal rate 30-500ml/min Lost gas volume needs to be considered in closed circuit anesthesia. Gases must pass through various water traps and filters. Transport delay time Associated RISE TIME Mainstream/ Non- diverting Sample cell placed directly in the patients breathing circuit. Inspiratory and expiratory gases pass directly through the IR path Increase in dead space and is heavy Sample cell heated to 40 degrees to minimize condensation. Increased risk of facial burns. Requires daily calibration. No delay time RISE TIME is faster

14. Types of capnometers

15. Capnography waveforms Interpretation of TIME

16. Capnographic Waveform Normal waveform of one respiratory cycle Similar to ECG Height shows amount of CO 2 Length depicts time

17. 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.

18. Capnographic Waveform Capnograph detects only CO 2 from ventilation No CO 2 present during inspiration Baseline is normally zero Baseline

19. Capnogram Phase I Dead Space Ventilation Beginning of exhalation No CO 2 present Air from trachea, posterior pharynx, mouth and nose No gas exchange occurs there Called “ dead space ”

20. Deadspace

21. Capnogram Phase I Baseline Beginning of exhalation A B I Baseline

22. Capnogram Phase II Ascending Phase CO 2 from the alveoli begins to reach the upper airway and mix with the dead space air Causes a rapid rise in the amount of CO 2 CO 2 now present and detected in exhaled air

23. Capnogram Phase II Ascending Phase CO 2 present and increasing in exhaled air II A B C Ascending Phase Early Exhalation

24. Capnogram Phase III Alveolar Plateau CO 2 rich alveolar gas now constitutes the majority of the exhaled air Uniform concentration of CO 2 from alveoli to nose/mouth

25. Capnogram Phase III Alveolar Plateau CO 2 exhalation wave plateaus A B C D I I I Alveolar Plateau

26. Capnogram Phase III End -Tidal End of exhalation contains the highest concentration of CO 2 The “ end-tidal CO 2 ” The number seen on your monitor Normal EtCO 2 is 35-45mmHg

27. Capnogram Phase III End-Tidal End of the the wave of exhalation A B C D End-tidal

28. Capnogram Phase IV Descending Phase Inhalation begins Oxygen fills airway CO 2 level quickly drops to zero

29. Capnogram Phase IV Descending Phase Inspiratory downstroke returns to baseline A B C D E I V Descending Phase Inhalation

30. Capnography Waveform Normal range is 35-45mm Hg (5% vol ) Normal Waveform

31. a-A Gradient r r Alveolus PaCO 2 V e i n A t e y Ventilation Perfusion a rterial to A lveolar Difference for CO 2 Right Ventricle Left Atrium EtCO 2

32. End-tidal CO 2 (EtCO 2 ) Normal a-A gradient 2-5mmHg difference between the EtCO 2 and PaCO 2 in a patient with healthy lungs

33. Factors Affecting ETCO 2 Levels

34. Hyperventilation RR : EtCO 2 4 5 Normal Hyperventilation

35. Waveform: Regular Shape, Plateau Below Normal Indicates CO 2 deficiency Hyperventilation Decreased pulmonary perfusion Hypothermia Decreased metabolism Interventions Adjust ventilation rate Evaluate for adequate sedation Evaluate anxiety Conserve body heat

36. Hypoventilation 4 5 4 5 RR : EtCO 2 Normal Hypoventilation

37. Waveform: Regular Shape, Plateau Above Normal Indicates increase in ETCO 2 Hypoventilation Respiratory depressant drugs Increased metabolism Interventions Adjust ventilation rate Decrease respiratory depressant drug dosages Maintain normal body temperature

38. Bronchospasm Waveform Pattern Bronchospasm hampers ventilation Alveoli unevenly filled on inspiration Empty asynchronously during expiration Asynchronous air flow on exhalation dilutes exhaled CO 2 Alters the ascending phase and plateau Slower rise in CO 2 concentration Characteristic pattern for bronchospasm “ Shark Fin ” shape to waveform

39. Capnography Waveform Patterns Norma l Bronchospasm 4 5

40. Capnography Waveform Patterns Hypoventilation Normal 4 5 4 5 Bronchospasm Hyperventilation 4 5

41. Airway obstruction Cardiogenic oscillations Curare Cleft Esophageal Intubation

42. Rebreathing of CO 2 Faulty inspiratory valve Patient with single lung transplant Faulty inspiratory valve

43. Ruptured/ Leaking ET tube cuff Leak in side stream sample line Expiratory valve stuck open Electrical Noise

44. Volume Capnogram

45. Volume Capnogram

46. Acute Bronchospasm Changes in pulmonary perfusion

47. Advantages of volume capnogram Allows for estimation of the relative contributions of anatomic and alveolar components of V d . M ore sensitive than the time capnogram in detecting subtle changes in dead space that are caused by alterations in PEEP, pulmonary blood flow, or ventilation heterogeneity. A llows for determination of the total mass of CO2 exhaled during a breath and provides for estimation of V ˙ CO2 .

48. Uses of capnography

49. Detect ET Tube Displacement Confirm ET Tube Placement

50. Capnography in Cardiopulmonary Resuscitation Assess chest compressions Early detection of ROSC Objective data for decision to cease resuscitation Use feedback from EtCO 2 to depth/rate /force of chest compressions during CPR.

51. In Laparoscopic Surgeries 1.Non invasive monitor of PaCO 2 and can be used to adjust ventilation. 2.Detection of accidental intravascular CO 2 insufflation. 3.Helps to detect complications of CO 2 insufflation like pneumothorax.

52. Optimize Ventilation Use capnography to titrate EtCO 2 levels in patients sensitive to fluctuations Patients with suspected increased intracranial pressure (ICP) Head trauma Stroke Brain tumors Brain infections

53. Optimize Ventilation High CO 2 levels induce cerebral vasodilatation Positive: Increases CBF to counter cerebral hypoxia Negative: Increased CBF, increases ICP and may increase brain edema Hypoventilation retains CO 2 which increases levels CO 2

54. Optimize Ventilation Low CO 2 levels lead to cerebral vasoconstriction Positive: EtCO 2 of 25-30mmHG causes a mild cerebral vasoconstriction which may decrease ICP Negative: Decreased ICP but may cause or increase in cerebral hypoxia Hyperventilation decreases CO 2 levels CO 2

55. The Non-intubated Patient Capnography Applications Identify and monitor bronchospasm Asthma COPD Assess and monitor Hypoventilation states Hyperventilation Low-perfusion states

56. Capnography in Bronchospastic Conditions Air trapped due to irregularities in airways Uneven emptying of alveolar gas Dilutes exhaled CO 2 Slower rise in CO 2 concentration during exhalation A l v e o l i

57. Capnography in Bronchospastic Diseases Uneven emptying of alveolar gas alters emptying on exhalation Produces changes in ascending phase (II) with loss of the sharp upslope Alters alveolar plateau (III) producing a “ shark fin ” A B C D E I I III

58. Capnography in Bronchospastic Conditions Asthma Case Initial After therapy

59. Capnography in Bronchospastic Conditions Pathology of COPD Progressive Partially reversible Airways obstructed Hyperplasia of mucous glands & smooth muscle Excess mucous production Some hyper-responsiveness

60. Capnography in Bronchospastic Conditions Capnography in COPD Arterial CO 2 in COPD PaCO 2 increases as disease progresses Requires frequent arterial punctures for ABGs Correlating capnograph to patient status Ascending phase and plateau are altered by uneven emptying of gases

61. Capnography in Hypoventilation States Altered mental status Sedation Alcohol intoxication Drug Ingestion Stroke CNS infections Head injury Abnormal breathing CO 2 retention EtCO 2 >50mmHg

62. Capnography Applications on Non-intubated Patients New applications now being reported Pulmonary emboli CHF DKA r r O x y g e n O 2 V e i n A t e y

63. PULMONARY EMBOLUS

64. Transcutaneous and carbon dioxide monitors

65. Transcutaneous measurements of P O 2 (Ptc o 2) and P co 2 ( Ptc co 2) are monitoring methods that aim to provide noninvasive estimates of arterial O 2 and CO 2 , or at least trends associated with these variables. T ranscutaneous monitoring can be applied when expired gas sampling is limited. The measurements are based on the diffusion of O2 and CO2 through the skin . Used successfully in neonates and infants

66. Applied when expired gas sampling is limited Measurements are based on the diffusion of CO 2 and O 2 through the skin. W arming is used to facilitate gas diffusion . Such an increase in temperature promotes increased O 2 and CO 2 partial pressure at skin surface. Ptc o 2 is usually lower than PaO 2 , and Ptc co 2 is higher than Pa co 2 .

67. A transducer using a pH electrode to measure the Pco 2 (Stow- Severinghaus electrode ) is used. A change in pH is proportional to the logarithm of the Pco 2 change. For CO 2 monitors A temperature correction factor is used to estimate Paco 2 from Ptcco 2.

68. Uses of P tc co 2 Assess the efficacy of mechanical ventilation in respiratory failure. Laparoscopic surgery with prolonged pneumoperitoneum . Deep sedation for ambulatory hysteroscopy in healthy patient. Weaning from mechanical ventilation after off pump CABG.

69. Uses of P tc o 2 Detect hyperoxia in neonates Adults: Wound management peripheral vascular disease hyperbaric medicine.

70. Limitations Poor cutaneous blood flow Frequent calibration Slow response time Skin burns with prolonged application

71. References Understanding anesthesia equipment, 5 th edition Dorsch and Dorsch Miller’s Anesthesia 8 th edition Care fusion capnography handbook www.capnography.org

72. THANK YOU THE END