Better understanding of Capnography by Weaam Abdalla
- 3. Capnography: • Probably the least understood, non-invasive vital sign.
- 4. Learning Objectives: • History of capnography. • CO2 production, transport and elemination. • Differentiate ventilation from oxygenation • Define capnography. • The differences between Mainstream and Side stream capnography. • Articulate barriers to capnography technology use.
- 5. History: • Based on a discovery in 1875 by chemist Joseph Black He noted the properties of a gas released during exhalation that he referred to as “fixed air” That fixed air was determined to be carbon dioxide.
- 6. Oxygenation VS Ventilation • Oxygenation: The addition of oxygen to any system, Oxygenation may also refer to the process of treating a patient with oxygen • Ventilation : The movement or exchange of air between the environment and the lungs via inhalation and exhalation. BASICALLY: to take in oxygen (O2 ) and eliminate carbon dioxide (CO2 ).
- 10. What Is Capnography? • Capnography is an objective measurement of exhaled carbon dioxide (CO2 ) levels at the end of each breath. • commonly referred to as EtCO2. • The term capnography comes from the Greek word KAPNOS, meaning smoke. • Gives information about ventilation, cardiac output, distribution of pulmonary blood flow and metabolic activity. • The other method to measuere CO2 in the body is by arterial and venous blood gas, which is more invasive and costy.
- 11. Terminology: EtCO2 : Concentration of CO2 against time
- 12. Colour change colormetry: has fale +ve results because of high sensetivity.
- 13. Mechanism: The Beer–Lambert law : chemical analysis measurement to determine the concentration of chemical species that absorb light.
- 16. EtCO2
- 17. This gap will increase with decrease in pulmonary blood flow as in PE, COPD, ARDS. Alveolar dead space
- 19. Types: • Mainstream CO2 samples are taken directly from the airway. This method provides a very accurate reading because the sensor is at the actual airway, is widely regarded as the more accurate method of measuring EtCO2, old version was heavy, can cause skin burn. • Side stream: CO2 uses a sensor that is located inside the monitor instead of an external sensor. The patient’s exhalation air is pulled through a small tube, usually 6-8’ long, from the sample site and into the monitor.
- 22. Causes of abnormal Etco2: • High: Hypoventilation. Hyperthermia. NaHCO3. Rebreathing. Low: Hyperventilation Hypothermia. Decreased COP. PE. Hypovolemia. Hypotension.
- 23. Instrument factors: • Kinking. • Disconnection. • Leak. • Occlustion. • Malfunctiong. • Expiratory valve malfunction.
- 24. Advantages: • Tube Misplacement/Displacement (unrecognized esophageal intubation) • Improved Resuscitation Outcomes. • Better CPR, quality of chest compression, and ROSC. • Assessment of Pulmonary Circulation and Respiratory Status. • Optimization of Mechanical Ventilation, patient-ventilator asynchrony. • PCA. • Procedure sedation. • Transfer of critically ill patients. • Early detection of apnea or sever airway obstruction. • Asthma/OSA.
- 25. Barriers to Use of Capnography: • Very high RR. • Secretions. • NaHCO3. • ECMO and Dialysis. • Knowledge: Differing EtCO2 technologies. Varying features and functions. Initial training of staff/physicians. • Expense to hospital.
- 26. SpO2 EtCO2: • Familiar. • easy concept. • Easy to use and understand • Non-invasive. • Pain free What dose it tell us: • Oxygenation status. • Detects hypoxia • Quick and reliable indicator… but is it quick enough? 1-2 min delay. • Will show an elevated saturation for up to several minutes, as it takes time for existing oxygen saturation to decline. • May fail to detect respiratory deterioration, particularly if a patient is receiving supplemental oxygen. • May not detect left shift in oxy Hb disociation curve. • Easy to use. • Easy to interpret . • Non-invasive, • Pain free. What dose it tell us: • Ventilation status • Detects respiratory rate changes.and apnea. • Detects ventilation potential changes with each breath. • Quick, reliable indicator; changes caught sooner, reflects changes in ventilation within 10 seconds. • Impaired gas exchange is visible 30-60 seconds sooner than with SpO2.
- 29. Rebreathing: Falty expiratory valve. Inadeqet inspiratort flow. Malfunction CO2 absorpant. Larg heart
- 32. We need to challenge our current monitoring practices and no longer believe that: • Trusting that intermittent spot checks of vital signs is sufficient. • Continuously monitoring only high risk patients. • Relying on Pulse Ox alone to detect respiratory depression.
- 33. Take home messege: • Regardless of the future, capnography is an emerging and growing parameter. • capnography is a life-saving modality as it provides an early indicator of potentially 2 critical conditions. • Knowledge is power—educate yourself on capnography!
- 34. • Can EtCO2 replaces SPO2?
- 35. Test: