Pulse Oximetry & Capnography

Pulse Oximetry & Capnography
Ray Taylor Valencia Community College Department of Emergency Medical Services

Notice All rights reserved.
Slide show used with permission only for the purposes of educating emergency medical providers (EMTs and Paramedics) No portion of this presentation may be reproduced, stored in a retrieval system in any form or by any means (including but not limited to electronic, mechanical, photocopying etc.) without prior written permission from the author

CAPNOGRAPHY IS THE VITAL SIGN FOR VENTILATION (what we should evaluate) OXIMETRY IS THE VITAL SIGN FOR OXYGENTATION (what we have historically used)

Capnography Definition:
Noninvasive measurement of the partial pressure of C02 in exhaled air Provides instantaneous information about Ventilation How effectively C02 is being eliminated by the pulmonary system Perfusion How effectively C02 is being transported through the vascular system Metabolism How effectively C02 is being produced by cellular metabolism

Physiology Review The fundamental purpose of ventilation and circulation is to supply O2 to the tissues’ cells and to remove CO2. The conducting airways (from the nasal/oral cavities extending to the smallest bronchioles) serve as a conduit for gas exchange between the atmosphere and the cells. This portion of the respiratory system is referred to as “anatomic dead space,” because no gas exchange occurs there. On average, 30% of inspired tidal volume is “dead”. Respiration (gas exchange) occurs in the alveoli.

Physiology Review All cells produce CO2 as a metabolic byproduct of the oxidative breakdown of fuels. Factors such as body temperature, exercise and nutrition affect the amount of CO2 produced. CO2 easily diffuses out of the cells and into the vasculature, where it is carried back to the right side of the heart and on to the pulmonary system - to the pulmonary capillaries surrounding the alveoli.

Physiology Review As ambient, nearly CO2-free air is drawn into each alveolus during inspiration, the CO2 in the blood diffuses across the capillary and alveolar walls into the alveolar space. Normally, one pass of the blood through the alveolar capillary bed allows the partial pressures of CO2 in the alveoli and the arterial blood to nearly equalize.

Respiratory Physiology
CO O CO 2 2 2 CO . 2 Blood from right side of heart Aveolus (low in O, 2 high in CO) O Diffusion - passage of solution from area of higher concentration to lower concentration O2/ CO2 dissolve in water and pass through alveolar membrane by diffusion Oxygen content of blood Dissolved O2 crosses the pulmonary capillary membrane and binds to the hemoglobin (Hgb) of red blood cell. Oxygen can either be bound to hemoglobin or dissolved in plasma O2 saturation = % of hemoglobin saturated Normally greater than 98% O 2 2 2 CO Blood to left CO 2 2 side of heart Reoxygenated blood (high in O, low in CO) Capillary 2 2 Red blood cells

Exhalation Exhalation can be divided into 3 phases:
Phase 1: Expiration from dead bronchiolar space – no CO2 yet exhaled Phase 2: Mixture of dead space air + alveolar CO2 reaches the mouth Known as alveolar washout and recruitment Phase 3: Nearly pure, CO2-rich alveolar air is exhaled Called the alveolar plateau

End-tidal CO2 The peak partial pressure of CO2 during exhalation (the highest level of expired CO2 reached during exhalation) is known as the end-tidal CO2 (EtCO2). Normally occurs at the end of the alveolar plateau EtCO2 is a reflection of alveolar ventilation, CO2 production and pulmonary blood flow. Can be thought of as the blood pressure of metabolism

End-tidal CO2 In healthy people, the EtCO2 is within 5 mmHg of the partial pressure of CO2 in arterial blood (PaCO2). Normal values of both are between mmHg. 4.5% – 6 %

Normal Endtidal CO2 Normal 35-45 mmHg
Waveform reflects how close numerical value is to actual end tidal volume Square = GOOD Hump = BAD

Depth = Height

Pulse Oximetry The pulse oximeter is a noninvasive device that measures the oxygen saturation of your patient’s blood. The pulse oximeter consists of a probe attached to the patient's finger or ear lobe which is linked to a computerized unit.

How does a Pulse Oximeter work?
The probe directs two lights (one red, one infrared) through tissue (finger, earlobe, etc.) The lights are absorbed differently depending on oxygen attached to hemoglobin molecule The result is a measurement of the patient’s oxygen saturation on the hemoglobin molecule The oximeter is also dependent on a pulsatile flow. Where flow is sluggish (i.e. hypovolemia or vasoconstriction) the pulse oximeter may be unable to function. The computer within the oximeter is capable of distinguishing pulsatile flow from other more static signals (such as tissue or venous signals) to display only the arterial flow. Some oximeters show a flow wave or flash a light in sync with the patient’s pulse. A flashing light inconsistent with the patient’s palpable pulses would indicate a peripheral flow problem and result in an inaccurate or “error” reading.

Function of Pulse Oximeter
Determines delivery of oxygen to peripheral tissues Measures the oxygen saturation of your patient’s blood Helps to quantify the effectiveness of your interventions oxygen therapy, medications, suctioning, BVM

Indications A depressed respiratory drive (e.g., narcotic overdose)
An increased resistance in the respiratory airways (e.g., asthma) A reduced capacity of the blood to transport oxygen (e.g., shock, anemia) All patients (additional vital sign) Other indications include: Paralysis of the respiratory muscles (e.g., cervical spine injury) A decreased compliance of the lungs and thoracic wall (e.g., adult respiratory distress syndrome [ARDS]) Chest wall abnormalities (e.g., flail chest) A decreased surface area for gas exchange (e.g., atelectasis) An increased thickness of the respiratory membrane (e.g., ARDS) Ventilation and perfusion mismatching (e.g., pulmonary embolus)

SaO2 v. SpO2 PaO2 is actual amount of oxygen dissolved in arterial blood measured by blood gases expressed in mmHg SaO2 is percentage of hemoglobin saturated by oxygen expressed in percentage SpO2 is percentage of hemoglobin saturated by oxygen measured by pulse oximeter

Normal Pulse Oximetry Readings
Normal lab values range between % Readings between 93% and 97% may be normal for some patients (COPD) Oxygen (at minimum) should be applied for readings below 90% LACoFD guidelines will require oxygen administration for any patient with pulse ox of less than 90% Don’t wait for a low pulse ox reading to treat the patient. Clinical signs of respiratory distress may be evident prior to acknowledgment by the pulse oximetry monitor. They may include: Alterations in mental status Severe cyanosis Absent breath sounds One or two word dyspnea Tachycardia Pallor and diaphoresis Presence of retractions and/or the use of accessory muscles to assist with breathing Tripod position By comparing pre and post oxygen application readings you should be able to see if O2 delivery results in improvement.

Pitfalls of the Pulse Oximeter
Certain medical conditions can alter the machines interpretation, and give false readings Certain environmental conditions can also produce false reading The oxygen saturation should always be above 95%. In patients with long standing respiratory disease or those with cyanotic congenital heart disease readings may be lower and reflect the severity of the underlying disease. Like all monitoring the reading should always be interpreted in association with the patient's clinical condition.

In the following situations the pulse oximeter readings may not be accurate:
A reduction in peripheral pulsatile blood flow produced by peripheral vasoconstriction (hypovolemia, severe hypotension, cold, cardiac failure, some cardiac arrhythmias) or peripheral vascular disease. The presence of methemoglobin will prevent the oximeter from working accurately and the readings will tend towards 85%, regardless of the true saturation. Other situations when the pulse oximeter reading may not be accurate: Venous congestion, may produce venous pulsations which may produce low readings with ear probes. Venous congestion of the limb may affect readings as can a badly positioned probe. When readings are lower than expected it is worth repositioning the probe. Bright overhead lights in may cause the oximeter to be inaccurate. Shivering may cause difficulties in picking up an adequate signal. Anemia may affect the reading. Nail polish may cause falsely low readings. The units are not affected by jaundice, dark skin.

In the following situations the pulse oximeter readings may not be accurate:
Carboxyhemoglobin( hemoglobin combined with carbon monoxide [COHb]) is lumped in with oxyhemoglobin (O2Hb), thus producing incorrect readings. A person could have 15% COHb on board (or more), plus 80% O2Hb, but the pulse- Ox reading would still be 95% saturation. Pulse oximeters are "blind" to CO because of the two wavelengths of light used to make measurements.

Pulse Oximetry v. Capnography
Oxygenation is measured by pulse oximetry Ventilation is measured and monitored with capnography Oxygenation, the process of getting oxygen to the tissues for metabolism, is measured by pulse oximetry. Ventilation, the process of eliminating CO2 from the body, is measured by capnography.

Comparison of Capnograhy and Oximetry
Capnographs and pulse oximeters present different views of the same cardiopulmonary processes. Oximeters measure saturated hemoglobin in peripheral blood and provide additional information about the adequacy of lung perfusion and oxygen delivery to the tissues. Many sources recommend monitoring both SpO2 and EtCO2 on intubated and non-intubated patients. However, pulse oximetry is a late indicator of O2 supply, and is less sensitive than capnography. It does not afford a complete picture of ventilatory status.

Comparison Accurate pulse oximetry measurement is dependent upon adequate peripheral perfusion and may be unreliable in patients who have compromised peripheral circulation. Capnography continuously and nearly instantaneously measures pulmonary ventilation and is able to rapidly detect small changes in cardio-respiratory function before oximeter readings change. Healthy patients can maintain SaO2 > 90% for minutes even with inadequate ventilation.

Terminology Capnos = smoke Capnometer = number (EtCO2)
Capnograph = number + digitized signal

Capnography (Quantitative EtCO2 Detectors)
Capnography is a form of noninvasive monitoring of the end-tidal carbon dioxide (EtCO2) levels in the patient’s exhaled breath. Capnography refers to a unit that displays both a numeric EtCO2 value and a CO2 waveform (capnograph). Internet Resources:

Definitions Capnography is the measurement of exhaled CO2
Capnometer gives a numerical or quantitative (precise) measurement of exhaled CO2 Capnograph gives both a numerical reading of exhaled CO2 plus a tracing End-tidal CO2 (EtCO2) is the measurement of CO2 at the end of exhalation The colormetric device we use is a capnometer. There are also electronic devices that are capnometers and only give a numerical value for CO2. A capnograph gives both a numerical value and graphical representation of the CO2 level similar to an EKG. The graphical representations in capnography are called “waveforms”

Cardiac ECG

Pulmonary ECG

Oxygenation and Ventilation
Oxygen -> lungs -> alveoli -> blood Oxygen breath CO2 muscles + organs lungs Oxygen CO2 cells energy blood Oxygen + Glucose CO2

Phase I (A-B) Dead Space Ventilation Represents the beginning of exhalation where the dead space is cleared from the upper airway C D A B E I Phase I is baseline. Inhalation and dead space ventilation are occurring. There is normally no carbon dioxide present so the baseline is on zero.

Phase II Ascending Phase (B – C) Represents the rapid rise in C02 concentration in the breath stream as the C02 from the alveoli reaches the upper airway C D I I A B E This upstroke in the ascending phase is usually steep as the proportion of alveolar air quickly increases. As you will see later, phase II is altered if there is any obstruction in the airway.

Phase III Alveolar Plateau(C-D) Represents the C02 concentration reaching a uniform level in the entire breath stream from alveolus to the nose. C D I I I A B E The alveolar plateau is flat with a slight upward tilt toward the end.

End-Tidal CO2 Point D represents the maximum C02 concentration at the end of the tidal breath (Appropriately named end-tidal C02). This is the number that appears on the monitor E n d - T i d a l C D A B E End of phase III illustrates the end of exhalation which called the “end-tidal CO2”

Phase IV (D-E) Descending Phase-Inspiratory Limb Represents the inspiratory cycle
When inspiration does begin again, the amount of measured CO2 quickly drops to zero. The return to the baseline is called Phase IV.

Normal CO2 Waveform

How does Capnography work?
The most common technologies utilize infrared (IR) spectroscopy Measures the absorption of wavelengths of IR light by CO2 molecules as the IR light passes through a gas sample The amount of IR light that is absorbed reflects the amount of CO2 present and electronically calculates a value Mainstream/Sidestream The value that we are most interested in occurs at the point of maximum exhalation and is known as the end-tidal CO2 (EtCO2) CO2 value obtained from capnography should, under most circumstances, be considered a close approximation of an ABG (PaCO2). The expected difference between an EtCO2 measurement and that of a PaCO2 is known as the PACO2-PetCO2 gradient. The EtCO2 can normally be expected to be from 2-5mm Hg less than the PACO2. Nonetheless, it can be used as an estimated measure of PACO2 given a normal matching of ventilation and perfusion.

Clinical Application of ETC02
Verification of endotracheal tube placement Continuous monitoring of tube location during transport Gauging the effectiveness of resuscitiation and prognosis during cardiac arrest Titrating EtC02 levels in patients with suspected increases in intracranial pressure Determining prognosis in trauma Determining adequacy of ventilation

Physiology of Capnography
During cellular respiration, small amounts of CO2 are excreted via exhalation When no cellular respiration is occurring, even if ventilation is, there will be no CO2 exhaled In poor perfusion states (cardiac arrest) no CO2 is transported to the lungs to be exhaled, so a low reading will occur In poor ventilation states (hypoventilation) CO2 is retained, so a high reading will occur During poor perfusion and ventilation states, some CO2 may actually be exhaled, but may not be in sufficient quantity enough to create a color change on the colorimetric device. If the patient is not breathing at all, then no reading will result on the capnometer. If the patient is hyperventilating and blowing off a lot of CO2, then their reading will be low (<35mmHg) on the capnometer. If the patient is hypoventilating (agonal or irregular respirations), then they will be retaining CO2, which will result in a high (>35mmHg) reading on the capnometer. When the patient has poor perfusion (shock, cardiac failure, etc.), no CO2 is being transported to the lungs, so it cannot be exhaled, and the reading on the capnometer will be low (<35mmHg).

ETT Algorithm According to the AHA, in the prehospital setting, unrecognized misplacement of tracheal tubes has been reported in as many as 25% (Katz and Falk, 2001) of patients. In an effort to protect against unrecognized esophageal intubations, current AHA training programs strongly recommend that CO2 detection devices be placed on all intubated patients.

ET Tube Verification (It can be harder than we think)
RSI Inexperience Facial Trauma Blood Syringe/Bulb Trachlight Auscultation Infant/child I just know Combitube Seizures Experience Movement Short/fat neck Vomitus Mucus Recreational Drugs

Confirmation of ET Tube Placement
Data confirm that physical assessment procedures to confirm ET tube placement can be misleading. Movement of air through the esophagus may be difficult to differentiate breath sounds, and may create chest rise. Breath sounds and/or normal chest wall expansion may be difficult to confirm in victims with traumatic thoracic injury. Lung sounds can be transmitted to the epigastrium in peds Misting appears in a high % of esophageally-placed ET tubes. Difficult to confidently confirm ET tube placement in patients with severe bronchoconstriction. Unvisualized nasal ET tubes may be difficult to confirm.

Intubation The ETT algorithm should effectively eliminate the possibility of an esophageal intubation from going undetected. It includes a: Physiologic method (ET CO2 detection) Clinical method (auscultation)

Colorimetric CO2 (Qualitative EtCO2 Detectors)
When gas exchange from proper BVM or ET ventilation is adequate, small amounts of CO2 are excreted from the patient via exhalation. If a sufficient concentration of CO2 is detected, the color strip will change from purple to tan to yellow. The yellow color indicates adequate ventilation and good air exchange. Colorimetric CO2 detection devices are placed on the BVM and a chemical reaction occurs that results in a color change from purple to various shades of yellow in the presence of CO2. Due to reduced pulmonary perfusion, except for that provided by CPR, the color change may be weak or absent. Colormetric CO2 detection devices are still considered excellent adjuncts for confirming and monitoring endotracheal tube placement; however, they are essentially limited to that role. Like all monitoring the results should always be interpreted in association with the patient's clinical condition.

Colorimetric CO2 Uses litmus paper that changes color when it comes in contact with CO2 Will not change color if no CO2 is flowing across paper Color strip will change from purple to tan to yellow Color can change from breath to breath The yellow color indicates adequate ventilation and good air exchange LACoFD guidelines require that a colorimetric device is used for every intubated patient. There is a place on the PCR for the color observed during ventilation of the intubated patient. Colorimetric CO2 detection devices are placed on the BVM and a chemical reaction occurs that results in a color change from purple to various shades of yellow in the presence of CO2. Due to reduced pulmonary perfusion, except for that provided by CPR, the color change may be weak or absent. Colorimetric CO2 detection devices are still considered excellent adjuncts for confirming and monitoring endotracheal tube placement; however, they are essentially limited to that role. Like all monitoring, the results should always be interpreted in association with the patient's clinical condition.

Fun Facts about Colorimetric Devices
A Range (Purple): <4 mmHg EtCO2 0.03% to < 0.5% EtCO2 B Range (Tan): 4 to <15 mmHg EtCO2 0.5% to < 2% EtCO2 C Range (Yellow): 15 to 38 mmHg EtCO2 2% to 5% EtCO2 Evaluate color of device after 6 full breaths. This allows any CO2 in the stomach (produced by the ingestion of certain beverages and medications, or by expired air bagged into the stomach prior to intubation) to be blown off. Inaccurate if contaminated with secretions, blood, emesis, acidic meds, etc.

Pitfalls of the Colorimetric CO2 Detection Devices
Cannot provide a specific CO2 value Susceptible to failure if litmus paper is contaminated with body fluids (airway secretions, vomit, etc.) Has limited time value (normally <2 hours Subject to expiration (usually 2 years) Six ventilations are necessary prior to interpretation in cardiac arrest patient to ensure potential residual CO2 has been removed

Indications for Capnography
All intubated patients colorimetric capnometer electronic capnographer AHA, NAEMSP, ACEP all mandate use of secondary devices to confirm tube placement All critical care patients According to the AHA, in the prehospital setting, unrecognized misplacement of tracheal tubes has been reported in as many as 17% of patients. The American College of Emergency Physicians (ACEP) and National Association of EMS Physicians (NAEMSP) have both drafted position papers mandating the use of secondary devices, including EtCO2 measurements, to verify ET tube placement. The American Society of Anesthesiology has compiled a database of adverse events in the operating room and postoperative setting. The results of their survey, reported in the American Society of Anesthesiology (ASA) Closed Claims Project, concluded that monitoring devices would have completely prevented 32% of the morbidity and mortality. In the 1,097 claims examined between 1974 and 1988, it was revealed that the combined use of pulse oximetry and capnography could have prevented 93% of the mishaps deemed preventable.1

Waveform Displays (Quantitative Device)
The waveform (capnograph) provides a graph measured in time of the inspiratory and expiratory phases of the respiratory cycle. By interpreting the waveform we can make a number of assumptions about the clinical stability of a patient and the effectiveness of intervention. In a normal waveform, there is information regarding the patient’s: respiratory rate EtCO2 value in mm Hg length of the various phases of the cycle represented in time.

Capnography The waveform is divided into 4 phases.
Phases I, II and III occur during, and reflect, the three phases of exhalation. Phase IV occurs during, and reflects, inspiration.

Capnogram: Phase I Phase I occurs during exhalation of air from the anatomic dead space, which normally contains no CO2. This part of the curve is normally flat, providing a steady baseline.

Capnogram: Phase II Phase II occurs during alveolar washout and recruitment, with a mixture of dead space and alveolar air being exhaled. Phase II normally consists of a steep upward slope.

Capnogram: Phase III Phase III is the alveolar plateau, with expired gas coming from the alveoli. In patients with normal respiratory mechanics, this portion of the curve is flat, with a gentle upward slope. The highest point on this slope represents the EtCO2 value.

Capnogram: Phase IV Atmospheric air contains negligible amounts of CO2. Phase IV occurs during inspiration, where the EtCO2 level normally drops rapidly to zero. Unless CO2 is present in the inspired air, as occurs when expired air is rebreathed This part of the waveform is a steep, downward slope.

Phases of ventilation

Normal capnography

Capnography Waveform Patterns
Normal 4 5 Hyperventilation A comparison of three common waveforms: normal, hyperventilation and hypoventilation. Teaching Note: A review of the four phases, normal range and differences is helpful to some students 4 5 Hypoventilation

Apnea/Esophageal Intubation Prolonged cardiac arrest with diffuse cellular death Tracheal placement with inadequate pulmonary blood flow (poor chest compressions) ETT obstruction Complete airway obstruction distal to the ETT (eg, foreign body) Technical malfunction of the monitor or tubing

Tracheal Intubation

Esophageal Intubation
No capnography reading (waveform plus or EtCO2 detection) via your BVM, you are not in. “Full waveform is essential”

Unsuccessful Intubation

Comparison Capnograph
The tube has been extubated and is no longer in the trachea Remove at once!!

LMA with Capnography How successful is capnography when utilizing an LMA? Actually, you will get a waveform and numerical reading.

Abnormal Tracings Rebreathing Cause:
Breathing in a mixture of both oxygen and carbon dioxide (think rebreather mask) A waveform that does not return to the baseline during inspiration indicates that rebreathing of exhaled gas is occurring.

Abnormal Traces Sloping Plateau Cause:
Obstructive airway disease, because of impairment of V/Q ratio. In patients with obstructive airways disease, the lungs are perfused with blood as normal, but the alveoli are unevenly ventilated. This is called a ventilation-perfusion mismatch. V:Q is the abbreviation used when referring to ventilation-perfusion. The desirable ventilation to perfusion is a ratio of 1, or V:Q=1. In patients with obstructive disease or constriction, such as pulmonary hypertension, HAPE, CHF, ARDS, or pulmonary emboli, the V:Q will not be 1. We call this a ventilation:perfusion mismatch, and the resultant waveform has an upslope to the B-C segment, rather than being relatively flat across. CO2 that is transferred to the alveoli from the bloodstream may take longer to exhale because of the narrowed bronchi. This delayed emptying of the alveoli varies in different part of the lungs. This can cause a difference in the I:E ratio, which is normally 1:1, 1:1.5 or 1:2. This results in the sloping plateau on the capnograph trace, as the CO2 from those parts of the lungs with more severe bronchial narrowing is exhaled later than those parts with less severe narrowing.

CO2 Waveforms Normal Bronchospasm

Trending is Key to monitoring Respiratory Failure
Acute exacerbation of COPD Asthma Pneumonia CHF Respiratory Muscle Fatigue Hypoventilation Syndromes IS THE PATIENT RESPONDING TO THERAPY OR NOT?

Trending Video versus Snapshot
Trending of capnography provides a continuous view of the patient’s ventilatory status Early detection allows for early intervention Trending is a simple tool that does not stress an already failing system

Phases of Asthma Hyperventilation mild Tiring moderate Tired severe

Phases of Asthma Severe 50+ Moderate 40 40 mmHg Normal 25-30 Mild

EtCO2 Trending 60 55 50 50 50 45 40

Using Capnography in Asthma
Diagnoses presence of bronchospasm Waveform Assesses severity of Asthma EtCO2 trends Gauges response to treatment

COPD Baseline CO2 is higher Follow CO2 trends to: Establish baseline
> 50mm Hg Follow CO2 trends to: Establish baseline Track response to treatment

COPD Determine who is a CO2 retainer COPD vs. CHF Waveform
EtCO2 trends COPD vs. CHF Waveform

Hypoventilation States
Altered mental status Abnormal breathing 45

Hypoventilation

Hypoventilation States
Sedation Analgesia ETOH intoxication Drug Ingestion Postictal states Head trauma Meningitis Encephalitis

Abnormal Traces Cardiac Oscillations Cause:
Cardiac impulses transmitted to capnograph The oscillations reflected on the capnograph trace result from transmission of cardiac impulses to the airways.

Abnormal Traces “Curare cleft” Cause:
Asynchronous spontaneous breathing in an intubated patient Asynchronous breathing can result when the patient has an underlying respiratory drive, but is also being ventilated mechanically. For example, when a paralysed patient starts tacking small breaths as the neuromuscular blacking agent reverses, deep “clefts” are seen on the capnograph trace.

What could a poor or non-existent wave form indicate?
With a poor to nonexistent waveform, the endotracheal tube is likely in the esophagus, though consider other possible causes, such as airway disconnection, ventilator failure, cardiac arrest (especially with poor BLS) or decompensated shock. Remember, if no CO2 is being exhaled, then no waveform or numerical reading will be displayed. 60 30 What could a poor or non-existent wave form indicate?

Case Study #1 32 yo 90 kg female presents in acute respiratory distress Cyanotic, short word sentencing Respiratory rate is shallow and labored at 24 Expiratory phase is prolonged due to gas trapping Heart rate of 140, strong and bounding at the radial BP 170/88

Patient is clutching her Albuterol inhaler (self-administered 15 puffs prior to your arrival) ETC02 value was beginning to rise EtC02: 52 mmHg

Treatment BLS assisted ventilations via Bag Valve Mask with 100% O2
Epinephrine 1:1000 SQ admin Paramedic prepares for nasal intubation

Patient Arrests As the nasal tube is being advanced, patient arrests
Paramedic pushes the tube in anyway, but it is found to be in the esophagus Tube immediately withdrawn

Tube Confirmation Cords visualized during intubation
Patient is successfully intubated orally Auscultation reveals no discernible breath sounds anterior chest wall Abdominal auscultation is equally silent Minimal chest rise Positive misting and condensation in the tube Bulb aspirated syringe flows free-air

What is the next step? Auscultation doesn't really help
SpO2 is not reading (before or after) Remains difficult to ventilate What other tool can you use to confirm the placement of the tube? What else could be going on with this patient? Are we 100% sure we are in the trachea?

YES!!! We have an ETCO2 EtC02=22 mm Hg

Case Study #2: Cardiac Arrest
42 year old 90 kg, male, involved in motorcycle vs. truck MVA. The patient is pinned under vehicle on highway approx. 8 min from local hospital Rapid extrication performed from underneath truck Pt. is unresponsive with weak, irregular carotid at 150bpm, and agonal respirations weak carotid Patient becomes pulseless and apneic, BLS/CPR is initiated The patient was found unconscious, in a full arrest. CPR was immediately initiated. The ABG represents was type of acid/base imbalance? Acid

Corresponding waveform
After intubation, the EtC02 read 25 and then dropped to 0 when the patient was moved Corresponding waveform C02 before the patient was moved This waveform could represent what situation? With a waveform present at the beginning it represents good CPR. With the loss after intubation and the EtC02 level dropping to 0, it is quite possible that the ETT is in the esophagus. After the patient was moved

Where is the tube???? Provider checked the number at the lip
It had not changed Listened to Breath Sounds They were less audible The EtC02 was 25, then dropped to 0 Normal EtC02 is between 35 to 45 mm Hg

The Endotracheal tube was removed and the patient was reintubated
Corresponding waveform CO2 now back up to 25mmHg With an improved waveform, the possibility of an esophageal intubation was confirmed. The next ABGs were improved as well as the patients blood pressure.

Case Study #3 A 12 year old boy presented in acute respiratory failure with copious secretions and was successfully orally intubated and placed on a ventilator. The patient remained obtunded, cyanotic and had little airway movement on auscultation.

Presentation What does this waveform show? Unconscious & unresponsive
Respiration's unassisted remain agonal Heart rate of 136 strong and regular at the radial Blood Pressure 138/56 ETCO2 32 mm HG What does this waveform show?

Answer: A slow upstroke and incomplete emptying-
What could you do therapeutically? Answer:

The patient was suctioned and given a bronchodilator treatment
What does this waveform show?

Answer: The waveform shows less obstruction and more of an alveolar plateau = improved air movement

Case Study # 4 70 year old 60 kg female, status post cardiac arrest resuscitation by EMS She was resuscitated in the field and now being transported to hospital. Enroute Pt. is unconscious & unresponsive (orally intubated and on a vent) Vital Signs No spontaneous respirations BP 76/palpated Heart rate is palpable only at the carotid at 136 weak and irregular

Cardiac monitor reveals Sinus Arrhythmia with multi-focal PVC's and couplets
As you are debating Dopamine you notice a change... EtC02 drops from 30 to 18 mm Hg

Patient’s perfusion decreases more………….CO2 drops further
Now unable to palpate a carotid pulse CPR is Initiated

CPR was continued and palpable pulses with compressions were present
CPR was continued and palpable pulses with compressions were present. The improved waveform:

Attempt at defibrillation was unsuccessful
Cardiac compressions were stopped and the patient was found to be in ventricular fibrillation Attempt at defibrillation was unsuccessful

Repeat defibrillation
The patient is converted to normal sinus rhythm.

Simple use of EtC02: Capnography can be a useful tool in determining the effectiveness of pulmonary perfusion during a cardiac arrest.

CO2 Relationship to Cardiac Output
In cardiac arrest and other low cardiac output states, the patient’s capnography will be lower than normal.

Evaluation of Efficacy of CPR
Patients in cardiopulmonary arrest produce no EtCO2. During CPR (given a normal blood volume), effective chest compressions circulate enough blood to return CO2 from the tissue cells to the pulmonary circuit. Combined with effective ventilations, providers will be see improved EtCO2 values – most likely lower-than-normal levels. “EtCO2 concentration varies directly with pulmonary and systemic blood flows under conditions of constant minute ventilation. This relationship holds true even during extremely low blood flow rates.” Ann Emer Med, 3/1994, 23:3, p. 571

ETCO2 is also an indication of successful resuscitation
Sanders et al, 1989 JAMA noted a threshold for survival of ETCO2 >10 mmhg Successful = 15 (+/-) 4 Unsuccessful = 7 (=/-) 5

Cardiac Arrest/Successful Resuscitation

Predicting ROSC in Arrest
Studies have shown a correlation with EtCO2 levels during a code and ROSC. Annals of Emerg Med, June, 1995, 25:6, pages EtCO2 values can predict non-resuscitatable patients. We may see the development of protocols utilizing EtCO2 values in conjunction with the terminating rhythm to determine calling codes in the field. Most sources cite an EtCO2 value of 10 mmHg or less as an appropriate and predictive threshold. This is a terminating – not initial – value, measured after 20 minutes of standard ACLS interventions.

Early Detection of ROSC
If the patient in cardiac arrest has a return of spontaneous circulation, EtCO2 levels will rise quickly to a higher level. EtCO2 detection may be the earliest indicator of this improvement in perfusion, and should be confirmed by palpating for central and peripheral pulses. One study showed a marked rise in EtCO2 levels just before conversion of PEA to a perfusing rhythm. Before any return of measurable BP or palpable pulses! Annals of Emergency Medicine, June, 1995, 25:6, page

Causes of an Elevated ETCO2
Respiratory System Respiratory insufficiency Respiratory depression Obstructive lung disease Equipment Defective exhalation valve Metabolism Pain Hyperthermia Malignant hyperthermia Shivering Circulatory System Increased cardiac output - with constant ventilation

Causes of a Decreased EtCO2
Metabolism Overdose / sedation Hypothermia Circulatory System Cardiac arrest Embolism Sudden hypovolemia or hypotension Respiratory System Alveolar hyperventilation Bronchospasm Mucus plugging Equipment Leak in airway system Partial airway obstruction ETT in hypopharynx

Case Study #5 A 26 year old male is being transported on the ventilator. Vital signs are stable. A normal capnographic waveform is present.

Suddenly the capnograph changes to this:
EtC02: variable

What does this mean? What should you check?

Check the patient first
Then check the connections between the ETT and breathing circuit And what was found……?

Answer: A partial disconnection causing a leak in the circuit was detected. The problem is corrected and the waveform returns to normal

Summary Points Detection device > Diagnostic monitoring Static > Dynamic monitoring Advanced warning of ventilatory status Don’t be caught off guard Avoid backing into a critical situation Crash >elective Objective confirmation of clinical assessment

Thank you!

Pulse Oximetry & Capnography

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