Role of Capnography in emergency medicine

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Presentation Description

NBE training module for emergency medicine postgraduation


Presentation Transcript

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Role of Capnography in Emergency Room Dr.Venugopalan P P Director and Lead consultant in Emergency Medicine Aster DM Healthcare PG Teacher -NBE

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This session….. • What is Capnography • Basic science • Equipment • Waveform and interpretation • Clinical uses in Pre-hospital care and emergency room

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What is capography Capnography refers to the noninvasive measurement of the partial pressure of carbon dioxide CO 2 in exhaled breath expressed as the CO 2 concentration over time. Relationship of CO 2 concentration to time is graphically represented by the CO 2 waveform or capnogram

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Capnography Changes in the shape of the capnogram are diagnostic of disease conditions Changes in endtidal CO 2 EtCO 2 the maximum CO 2 concentration at the end of each tidal breathcan be used to assess disease severity and response to treatment. Capnography is also the most reliable indicator that an endotracheal tube is placement in the trachea

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Oxygenation and Ventilation Must be assessed in both intubated and spontaneously breathing patients. • Pulse oximetry provides instantaneous feedback about oxygenation • Capnography provides instantaneous informations 1. Ventilation how effectively CO 2 is being eliminated by the pulmonary system 2. Perfusion how effectively CO 2 is being transported through the vascular system 3. Metabolism how effectively CO 2 is being produced by cellular metabolism.

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Capnography- Part of standard care Routine part of anesthesia practice in Europe in the 1970s and in the United States in the 1980s. Now part of the standard of care for all patients receiving general anesthesia An emerging standard of care in emergency medical services emergency medicine and intensive care.

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How does it works Capnography uses infrared IR radiation to make measurements. Molecules of CO 2 absorb IR radiation at a very specific wavelength 4.26 µm The amount of radiation absorbed having a nearly exponential relation to the CO 2 concentration present in the breath sample. Detecting these changes in IR radiation levels using appropriate photodetectors sensitive in this spectral region Calculation of the CO 2 concentration in the gas sample

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Sampling Carbon dioxide CO 2 monitors measure gas concentration or partial pressure using one of two configurations: 1. Main stream 2. Side stream.

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Main stream Mainstream devices measure respiratory gas directly from the airway Sensor located on the airway adapter at the hub of the endotracheal tube ETT. Accurate Less response time Heavy Contaminated easily with secretions Configured for intubated patients

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Side stream Side stream devices measure respiratory gas via nasal or nasal-oral cannula Aspirating a small sample from the exhaled breath through the cannula tubing to a sensor located inside the monitor Light weight Slow response time Not contaminated easily Configured for both intubated and non-intubated patients.

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Side stream Configured to use high flow rates around 150 cc/min or low flow rates around 50 cc/ min. Flow rates vary according to the amount of CO 2 needed in the breath sample to obtain an accurate reading.

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Side stream systems Low flow systems 1. Lower occlusion rate from moisture or patient secretions 2. Accurate in patients with low tidal volumes 3. Useful in neonates infants and adult patients with hypoventilation and low tidal volume breathing. 4. Resistant to dilution from supplemental oxygen. High flow systems 1. Sampling at ≥100 cc/min 2. Inaccurate in neonates infants young children and in hypo ventilating adult patients

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CO2 monitors CO 2 monitors are either quantitative or qualitative. 1. Quantitative devices Measure the precise endtidal CO 2 EtCO 2 Number Capnometry Number and a waveform Capnography. 2.Qualitative devices Measure the range in which the EtCO 2 falls eg 0 to 10 mmHg or 35 mmHg

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Qualitative capnometric device Colorimetric EtCO 2 detector. A piece of specially treated litmus paper Changes color when exposed to CO 2 P urple for EtCO 2 3 mmHg Tan for 3 to 15 mmHg Yellow for 15 mmHg

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Qualitative capnometric device Primary use is for verification of ETT placement Correctly placed ETT in the trachea will change the color of the litmus paper from purple to yellow. Esophageal Tube placement will not change the color of the litmus paper which will remain purple

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Capnogram Phase 1 dead space ventilation AB beginning of exhalation where the dead space is cleared from the upper airway. Phase 2 ascending phase B- C Rapid rise in carbon dioxide CO 2 concentration in the breath stream as the CO 2 from the alveoli reaches the upper airway.

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Capnogram Phase 3 alveolar plateau CD CO 2 concentration reaching a uniform level in the entire breath stream from alveolus to nose. Point D- at the end of the alveolar plateau - the maximum CO 2 concentration at the end of the tidal breath -the endtidal CO 2 EtCO 2 . The number that appears on the monitor display. Phase 4 DE - the inspiratory cycle.

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ETCO2 Patients with normal lung function have characteristic rectangular capnograms Narrow gradients between alveolar CO 2 ie EtCO 2 and arterial CO 2 concentration PaCO 2 of 0 to 5 mmHg. Gas in the physiologic dead space accounts for this normal gradient

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Obstructive lung disease Impaired expiratory flow - more rounded ascending phase and an upward slope in the alveolar plateau Abnormal lung function and ventilation perfusion mismatch the EtCO 2- PaCO 2 gradient widens depending on the severity of the lung disease Hardman JG Aitkenhead AR. Estimating alveolar dead space from the arterial to endtidal CO2 gradient: a modeling analysis. Anesth Analg 2003 97:1846.

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ETCO2 in abnormal lung diseases The EtCO 2 in patients with lung disease is only useful for assessing trends in ventilatory status over time Isolated EtCO 2 values may or may not correlate with the PaCO 2

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How to approach CO2 wave analysis CO 2 is produced in metabolism and transported via perfusion Use the PQRST method to different types of emergency calls. 1. Proper 2. Quantity 3. Rate 4. Shape 5. Trending

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What is meant by PQRST approach Read PQRST in order Asking "What is Proper" • Consider what your desired goal is for this patient. "What is the Quantity" "Is that because of the Rate" • If so attempt to correct the rate. "Is this affecting the Shape" • If so correct the condition causing the irregular shape. "Is there a Trend" • Make sure the trend is stable where you want it or improving. • If not consider changing your current treatment strategy.

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Advanced Airway / Intubation

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Advanced Airway / Intubation P: Ventilation. Confirm placement of the advanced airway device. Q: Goal is 35-45 mmHg. R: 10-12 bpm ventilated.

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Advanced Airway / Intubation S: Near flat-line of apnea to normal rounded rectangle EtCO 2 waveform. • The top of the shape is irregular e.g. like two different EtCO 2 waves mashed together • Indicate a problem with tube placement. • A leaking cuff supra glottic placement or an endotracheal tube in the right main stem bronchus.

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Advanced Airway / Intubation • Shape is produced when one lung-often the right lung-ventilates first followed by CO 2 escaping from the left lung. • The waveform takes on a near-normal shape • Then the placement of the advanced airway was successful

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Advanced Airway / Intubation T: Consistent Q R and S with each breath. • Watch for a sudden drop indicating displacement of the airway device and/or cardiac arrest.

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Cardiac Arrest

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Cardiac Arrest P: Ventilation and perfusion. Confirmation of effective CPR. Monitoring for return of spontaneous circulation ROSC or loss of spontaneous circulation Q: Goal is 10 mmHg during CPR. Expect it to be as high as 60 mmHg when ROSC is achieved Murphy RA Bobrow BJ Spaite DW et al. Association between prehospital cpr quality and end-tidal carbon dioxide levels in out-of-hospital cardiac arrest. Prehosp Emerg Care. 2016203:369-377

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Cardiac arrest R: 10-12 bpm ventilated. S: Rounded low rectangle EtCO 2 waveform during CPR with a high spike on ROSC. T: Consistent Q R and S with each breath. Sudden spike indicating ROSC Sudden drop indicating displacement of the airway device and/or re-occurrence of cardiac arrest

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Optimized Ventilation

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Optimized Ventilation P: Ventilation. • Hyperventilation situations such as anxiety • Hypoventilation states such as opiate overdose stroke seizure or head injury. Q: Goal is 35-45 mmHg. • Control using rate of ventilation. • EtCO 2 is low i.e. being blown off too fast begin by assisting the patient to breathe more slowly or by ventilating at 10-12 bpm. • EtCO 2 is high i.e. accumulating too much between breaths begin by ventilating at a slightly faster rate. R: Goal is 12-20 bpm for spontaneous respirations 10-12 bpm for artificial ventilations.

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Optimized Ventilation S: Rounded low rectangle EtCO 2 waveform. Faster ventilation will produce wave shapes that are narrow or as tall since rapid exhalation contains less CO 2 . Slower ventilation produces wave shapes that are wider and taller as exhalation takes longer and more CO 2 builds up between breaths T: Consistent Q R and S with each breath trending towards optimal ventilation

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Shock P: Metabolism and perfusion. • Perfusion decreases and organs go into shock-whether hypovolemic cardiogenic septic or another type • Less CO 2 is produced and delivered to the lungs • EtCO 2 will go down even at normal ventilation rates • EtCO 2 can help differentiate between a patient whos anxious and slightly confused and one who has altered mental status due to hypo perfusion. • Indicate a patient whose metabolism is significantly reduced by hypothermia whether or not its shock-related. Q: Goal is 35-45 mmHg. • EtCO 2 35 mmHg in the context of shock indicates significant cardiopulmonary distress and the need for aggressive treatment Hunter CL Silvestri S Ralls G et al. A prehospital screening tool utilizing end-tidal carbon dioxide predicts sepsis and severe sepsis. Am J Emerg Med. 2016345:813-819

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Shock R: Goal is 12-20 bpm for spontaneous respirations 10-12 bpm for artificial ventilations. • Anxiety and distress can raise the patients respiratory rate. • Likewise it may cause a provider to ventilate too fast. • Faster rates will also lower EtCO 2 • Increase pulmonary venous pressure • Decreasing blood return to the heart in a patient whos already hypo perfusing Link MS Berkow LC Kudenchuk PJ et al. Part 7: Adult advanced cardiovascular life support: 2015 American Heart Association guidelines update for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 201513218 Suppl 2:S444-464.

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Shock S.Rounded low rectangle EtCO 2 waveform. T: Quantity will continuously trend down in shock. • Rate of ventilations will increase in early compensatory shock • Then decrease in later non-compensated shock. • The shape will not change significantly because of the shock itself

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Pulmonary Embolism

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Pulmonary Embolism P: Ventilation and perfusion. • EtCO 2 along with other vital signs can help you identify a mismatch between ventilation and perfusion. Q: Goal is 35-45 mmHg. • EtCO 2 35 mmHg in the presence of a normal respiratory rate and otherwise normal pulse and blood pressure may indicate that ventilation is occurring • Perfusion isnt as the embolism is preventing the ventilation from connecting with the perfusion. • Ventilation/perfusion mismatch Gravenstein JS Jaffe MB Gravenstein N et al. editors. Capnography. Cambridge University Press: Cambridge UK 2011.

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Pulmonary Embolism R: Goal is 12-20 bpm for spontaneous respirations 10-12 bpm for artificial ventilations. S: Low rounded rectangle EtCO 2 waveform. T:The quantity will continuously trend down as the patients hypo perfusion worsens

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Obstructed airway

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Asthma P: Ventilation. • The classic "sharks fin" shape is indicative of obstructive diseases like asthma • EtCO 2 can provide additional information about your patient Q: Goal is 35-45 mmHg. The trend of quantity and rate together can help indicate if the disease is in an early or late and 
 severe stage. R: Goal is 12-20 bpm for spontaneous respirations 10-12 bpm for artificial ventilations. DiCorpo JE Schwester D Dudley LS et al. A wave as a window. Using waveform capnography to achieve a bigger physiological patient picture. JEMS. 20154011:32-35

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Asthma S: Slow and uneven emptying of alveoli will cause the shape to slowly curve up resembling a sharks fin instead of the normal rectangle. T: • Early on the trend is likely to be a sharks fin shape with an increasing rate and lowering quantity. • As hypoxia becomes severe and the patient begins to get exhausted the sharks fin shape will continue but the rate will slow and the quantity will rise as CO 2 builds up.

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Mechanical obstruction

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Mechanical obstruction P: Ventilation. The "sharks fin" low- expiratory shape is present but is "bent" indicating obstructed and slowed inhalation as well. Q: Goal is 35-45 mmHg. R: Goal is 12-20 bpm for spontaneous respirations 10-12 bpm for artificial ventilations.

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Mechanical obstruction S: • Slow and uneven emptying of alveoli mixed with air from the anatomical "dead space" will cause the shape to slowly curve up • Phase 4 inhalation is blocked e.g. by mucous a tumor or foreign body airway obstruction T: • Hypoxia becomes severe and the patient begins to get exhausted and the rate will slow • Quantity will rise as CO 2 builds up.

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Emphysema or leaking alveoli in pneumothorax

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Emphysema or leaking alveoli in pneumothorax P: Ventilation. Emphysema may have so much damage to their lung tissue that the shape of their waveform may "lean in the wrong direction." Pneumothorax wont be able to maintain the plateau of phase 3 of the EtCO 2 wave. The shape will start high and then trail off as air leaks from the lung High on the left lower on the right shape. Q: Goal is 35-45 mmHg. Thompson JE Jaffe MB. Capnographic waveforms in the mechanically ventilated patient. Respir Care.2005501:100-108 discussion 108-109

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Emphysema or leaking alveoli in pneumothorax R: Goal is 12-20 bpm for spontaneous respirations 10-12 bpm for artificial ventilations. S: Top of rectangle slopes down from left to right instead of sloping gradually up. T: • Consistent Q R and S with each breath as always is our goal. • You should watch for and correct deviations

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Diabetes P: Ventilation and perfusion. EtCO 2 can aid in differentiation between hypoglycemia and diabetic ketoacidosis. Sometimes the difference is obvious but in other situations every diagnostic tool can help. Q: Goal is 35-45 mmHg. R: Goal is 12-20 bpm for spontaneous respirations. A hypoglycemic patient is likely to have a relatively normal rate of respiration. A patient whos experiencing diabetic keto acidosis will have increased respirations Lowering the quantity of CO 2 . CO 2 in the form of bicarbonate in the blood will be used up by the body trying to buffer the diabetic ketoacidosis. Low EtCO 2 can help indicate the presence of significant ketoacidosis. S: Rounded rectangle EtCO 2 waveform. T: Consistent Q R and S with each breath for hypoglycemia. A fast rate of respirations and low quantity for DKA. Bou Chebl R Madden B Belsky J et al. Diagnostic value of end tidal capnography in patients with hyperglycemia in the emergency department. BMC Emerg Med. 201616:7.

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Obesity and pregnancy

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Obesity and pregnancy P: Ventilation. Patients with poor lung compliance obese patients and pregnant patients may exhibit a particular wave shape that may indicate that theyre highly sensitive on adequate ventilation. Q: Goal is 35-45 mmHg. R: Goal is 12-20 bpm for spontaneous respirations 10-12 bpm for artificial ventilations. Yartsev A. Sep. 15 2015. Abnormal capnography waveforms and their interpretation. Deranged Physiology.Retrieved May 20 2017 from 

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Obesity and pregnancy S: • Rounded low rectangle EtCO 2 waveform • A sharp increase in the angle of phase 3 that looks like a small uptick or "pig tail" on the righthand side of the rectangle • CO 2 being squeezed out of the alveoli by the poorly compliant lung tissue obese chest wall or pregnant belly • Weight closes off the small bronchi. • Patients are progress quickly from respiratory distress to respiratory failure. T: Consistent Q R and S with each breath

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Fighting with ventilator or weaning out of relaxants

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Ventilator or breathing circuit related

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Ventilator or breathing circuit related

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Ventilator or breathing circuit related

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Ventilator or breathing circuit related

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CLINICAL APPLICATIONS FOR INTUBATED PATIENTS Verification of endotracheal tube ETT placement Continuous monitoring of tube location during transport Gauging effectiveness of resuscitation and prognosis during cardiac arrest Indicator of ROSC during chest compressions

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CLINICAL APPLICATIONS FOR INTUBATED PATIENTS Titrating end tidal carbon dioxide EtCO 2 levels in patients with suspected increases in intracranial pressure Determining prognosis in trauma Determining adequacy of ventilation

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CLINICAL APPLICATIONS FOR SPONTANEOUSLY BREATHING PATIENTS Spontaneously breathing non intubated patient capnography can be used for: Performing rapid assessment of critically ill or seizing patients Determining response to treatment in acute respiratory distress Determining adequacy of ventilation in obtunded or unconscious patients or in patients undergoing procedural sedation Detecting metabolic acidosis in diabetic patients and in children with gastroenteritis Providing prognostic indicators in patients with sepsis or septic shock

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ETCO2 - Practice Tips For EPs Intensivists and Anaesthesiologists

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Flat ETCO2 trace • Ventilator disconnection • Airway misplaced – extubation oesophageal intubation • Capnograph not connected to circuit • Respiratory/Cardiac arrest • Apnoea test in brain death dead patient • Capnongraphy obstruction

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Sudden drop in ETCO2 to Zero • Kinked ET tube • CO2 analyzer defective • T otal disconnection • Ventilator defective

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Sudden change in Base line Not to zero • Calibration error • CO2 absorber saturated check capnograph with room air • Water drops in analyzer or condensation in airway adapter

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Sudden increase in ETCO2 • ROSC during cardiac arrest • Correction of ET tube obstruction

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Elevated inspiratory Baseline • CO2 rebreathing e.g. soda lime exhaustion • Contamination of CO2 monitor sudden elevation of base line and top line • Inspiratory valve malfunction elevation of the base line prolongation of down stroke prolongation of phase III

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Identify Capnographic waves

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Air-leak - Loose connection between sampling tube and capnograph / broken connection or filter.

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Rebreathing capnogram of Mapleson D circuit.Bain circuit.

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Cardiogenic oscillations - Ripple effect - Seen during low frequency ventilation

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Contamination of capnograph Trend showing abrupt elevation of baseline and capnogram

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Trend capnogram during cardiac arrest / resuscitation.

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Upward slanting of phase 4. A normal variant in pregnant women during anesthesia.

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Trend showing gradual elevation of baseline.  Rebreathing

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Curare cleft

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Resembling curare cleft due to an artifact 1. Created by surgeon leaning on the chest 2. Pushing against the diaphragm during expiration. 3. Partial disconnect of main stream capnometer

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Dilution of expiratory gases by the forward flow of fresh gases during the later part of expiration when expiratory flow rate decreases below the forward gas flow rate

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Occasionally there can be a reverse phase 3 slope seen in patients with emphysema. Most like this may be due to destruction of alveolar capillary system in emphysematous lungs resulting in the delivery of carbon dioxide to expired gases.

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Endobronchial intubation may not result in a characteristic waveform. However occasionally it may be like the one seen in COPD or the above.

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CO2 waveform has two humps. Kypho - scoliosis resulted in a compression of the right lung. Differential lung emptying

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40 Flatlines

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Ventilator IMV breath during spontaneous ventilation

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Sticking inspiratory valve - Inspiratory flip - Red indicates possible rebreathing

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Air leak due to a broken connection between sampling tube and capnograph

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Transplanted lung

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Single lung transplant Biphasic capnogram recorded in a patient after single lung transplantation. Due to different populations of alveoli. The first peak represents expired carbon dioxide from allografted lung which has normal compliance good perfusion and good ventilation- perfusion ratios V/Q. The second peak most likely reflects expired carbon dioxide from the native lung because of slanted upstroke or steeper plateau is characteristic of the mismatched V/Q ratios

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Malignant hyperthermimia

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Spontaneous breathing - Adult

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Children and neonates-variations are normal and due to faster respiratory rates smaller tidal volumes relatively longer response time of the capnographs

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Pig tail Capnogram Tripati M Pandey M. Atypical "tails up" capnogram due to breach in the sampling tube of side-stream capnometer. J Clin Monit 200016:17-20. Slit sampling tube can result in a pig tail capnogram A terminal upswing at the end of phase 3 known as phase 4 can occur in pregnant subjects obese subjects and low compliance states

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Esophageal intubation

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Carbonated beverages in the stomach can result in abnormal capnograms with progressively decreasing CO2 values following esophageal intubation

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Elevation of base line A classic representation of rebreathing. Exhausted CO2 absorber

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Expiratory valve malfunction can result in prolonged abnormal phase 2 and phase 0 Inspiratory valve malfunction predominantly results in abnormal phase 0

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Unrecognized exhaustion of CO2 absorber resulted in substantial rebreathing and rising ETCO2 values. The closed circuit without functioning absorber mimicked Mapleson D circuit

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Contamination of capnometer results in the sudden elevation of base line as well as ETCO2 values

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Hypoventilation Rebreathing

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– “Thanks a lot .” Rate of removal Rate of Delivery Hypocapnia

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