Download EtC02 SpO2 Monitoring

EtCO2 & SpO2 Monitoring
Learning objectives
By the end of this module, the medic will be able to:
•
• Describe relationship between CO2 and metabolism
• Relate a normal capnograph to the phases of breathing
• Describe role of EtCO2 in ventilated patient • Describe non‐ intubated uses for EtCO2 in prehospital
setting.
• Describe the major trouble shooting of EtCO2 in Patients.
• Describe and understand the clinical differences between EtCO2 and SpO2 monitoring.
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The production of CO2 ‐ review
Pulmonary Blood Flow
Ventilation
Right Ventricle
A rte ry
C O2
O2
O2
Diffusion
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Vein
O xyg en
Left
Atrium
End Tidal CO2 ‐ what is It?
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•
•
•
•
•
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Capnograph displays breathing as a waveform.
ETCO2 is the amount of CO2 measured at the peak of the exhalation wave. ETCO2 is measured at the nose, mouth, or hub of the ET tube or King LT.
Normal values of ETCO2 in a resting individual will range between 35‐45 mm/Hg
<35 cm/H2O Hypocarbia (low levels of CO2 in the system)
>45 cm/H2O Hypercarbia (High levels of CO2 in the system)
Oxygenation and Ventilation What is the difference?
Two completely different and separate functions
•Oxygen is required for aerobic metabolism
•Oxygenation is the transport of O2 via the bloodstream to the cells
•Measured as SpO2 ( %)
•Ventilation is the exhaling of CO2 via the respiratory tract
•CO2 is the main byproduct of aerobic metabolism
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Ventilation
• Measured by the End‐tidal CO2
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–
Partial pressure (mm/Hg) of CO2 in the airway at the end of exhalation
–
Breath‐to‐breath measurement provides information within seconds (real – time)
–
Not affected by motion artifact, poor peripheral perfusion, ambient light or dysrhythmias (unless influenced significantly by systemic perfusion pressure)
Ventilation
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ǀ OBHG Education Subcommittee 2011 MD Pre-course Working Group
ETCO2 History in EMS • Colourmetric – CO2 detectors • Capnometry ‐ Numeric values
• Capnography – Waveform & numeric values
• Currently used for both non‐intubated and intubated patients
• Continuous breath‐to‐breath monitoring
• Equates to ECG monitoring in cardiac patient
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EtCO2 Waveforms and Printout
•Waveforms on screen and printout may differ in duration
•On‐screen EtCO2 waveform is condensed to
provide adequate information the in 4‐second view
• Printouts are in real‐time: Observe RR on device or printed paper
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EtCO2 Waveform
• Normal waveform of one respiratory cycle
• Similar to ECG
–
–
Height ‐ represents amount of CO2
Llength ‐ depicts time
Amount (mm/Hg)
Baseline (usually zero)
Time (sec)
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Capnograph Phase I: Dead Space Ventilation
Beginning of exhalation ‐ no CO2 present.
• Air from trachea, posterior pharynx, mouth and nose
no gas exchange occurs = “dead space”
B
A
I
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Capnograph Phase II: Ascending Phase
CO2 from the alveoli begins to reach the upper airway and mix with the dead space air • causes a rapid rise in the amount of CO2
CO2 now present and detected in exhaled air
C
B
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II
Alveoli
Capnograph Phase III: Alveolar Plateau
• CO2 rich alveolar gas now constitutes the majority of the exhaled air • Uniform concentration of CO2 from alveoli to nose/mouth
C
D
III
A
B
CO2 exhalation wave plateaus
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Capnograph Phase III: End‐Tidal point
• End of exhalation contains the highest concentration of CO2 ‐
This is the “end‐tidal CO2” number on your monitor
• Normal EtCO2 is 35‐45 mmHg
C
A
D
End-Tidal
B
End of the wave of exhalation
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Capnograph Phase IV: Descending Phase
•Inhalation begins
•Oxygen fills airway
•CO2 level quickly drops to zero
C
A
B
D
IV
E
Inspiratory down stroke returns to baseline
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Alveoli
EtCO2 Waveform
Normal range is 35 ‐ 45 mm/Hg
45
0
Normal Waveform
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Alterations in Respiratory Pattern
How does an alteration in the respiratory pattern affect the ETCO2 level and waveform?
Rule of thumb:
1. Any increase in rate/volume will decrease the level (number) and lower the waveform
2. Any decrease in rate/volume will increase the level (number) and height of the waveform
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EtCO2 Waveform
Normal
45
0
45
45>
0
Hyperventilation
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RR
EtCO2
EtCO2 Waveform
Normal
45
0
>45
45
0
Hypoventilation
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ǀ OBHG Education Subcommittee 2011 MD Pre-course Working Group
RR
EtCO2
Application of EtCO2 – Why? When?
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Monitor the effectiveness chest compression
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Detecting and monitoring ROSC or TOR –
Evaluate patients in hypercarbic or hypocarbic states
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Used on any patient that is being ventilated via BVM
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Both intubated and non‐intubated patients If the BVM is out – the End Tidal is on!!
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Historical methods of confirmation
Observe chest movement
Auscultate for breath sounds
Auscultate stomach
These methods are subjective and at times
unreliable
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Monitoring Effectiveness of Chest Compression
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0
Useful feedback from ETCO2
on depth, rate & force of chest compressions
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Monitoring Effectiveness of Chest Compression
High linear correlation between ETCO2 and cardiac output
• A decrease in ETCO2 reflects a critical reduction of cardiac output
• Low cardiac output reduces alveolar blood flow and fails to clear CO2 in the systemic
•
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Monitoring effectiveness of chest compression
CO2 continues to be produced by tissues but it is not transported back to the lungs. Effective compressions will transport some CO2 back to lungs ETCO2 of < 12 mm/Hg indicates poor quality CPR
Coach chest compressor to improve effectiveness and rotate every 2 minutes (utilize performance feedback from the monitor) 24
Detecting and Monitoring ROSC or TOR 25
Detecting and Monitoring ROSC or TOR
EtCO2 is an excellent tool to detect ROSC even before palpable pulse ! ETCO2 will rise immediately following pt.'s first heart beat, while a palpable pulse will be detected only after systemic perfusion pressure is 50 or more (Carotid). That can take up to a minute or more... 26
Detecting and Monitoring ROSC or TOR
So, what should we do when we detect a “jump” in ETCO2 waveform during the resuscitation?
• Do not check pulse (too early..)
• Continue chest compressions to the end of the 2 min.
cycle
• Can (resources permitting) start wiring the patient (B/P cuff, SPO2, 12 lead...)
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Detecting and Monitoring ROSC or TOR
EtCO2 has been shown to predict probability of outcome following resuscitation:
•May be used in the decision to cease resuscitation efforts
•If pt.’s ETCO2 <10 mm/Hg for more than 20 min. mortality rate is approx. 100%.
Source: Levine RL. End‐tidal carbon dioxide and outcome of out‐of‐hospital cardiac arrest. New England Journal of Medicine. 1997;337(5):301‐306.
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EtCO2 In The Non Intubated Patient
Common applications and characteristics of EtCO2 in non intubated patients:
Clinical course of SOB
Asthma and COPD
Hypoventilation and hyperventilation
Low perfusion (shock)
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EtCO2 in the Non Intubated Patient
Review:
What does EtCO2 reflect?
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 through the pulmonary capillaries
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EtCO2 in Bronchoconstricted Disease
• Uneven emptying of alveolar gas alters the “exhalation upslope angle”. • Produces changes in phase I with loss of the sharp upslope
• Alters phase III plateau producing a “shark fin”
C
A
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B
II
D
E
EtCO2 in Bronchoconstricted Disease
45
0
Initial
45
After therapy
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0
EtCO2 in Hypoventilation States
•In general, hypoventilation leads to retention of CO2 in the
tissues • Common causes to decreases respiratory efficiency:
•Sedation
•Alcohol or drug intoxication
•CVA
•TBI
•Spinal injury (Cervical & thoracic)
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EtCO2 in Hypoventilation States
45
0
•Slow rate
•High waveform
•Usually normal shape
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EtCO2 in Low Perfusion (Shock)
As systemic perfusion decreases (hypovolemia, PE) so does the amount blood flow to the lungs resulting in low ETC02 regardless of ventilatory status
45
0
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Oxygen Saturation
Pulse oximetry is a
tool used to monitor
the effectiveness of
the patient’s
respiratory status so
treatment can ensure
that adequate and
effective oxygenation
is maintained.
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Why use O2 Sat monitors?
Hypoxemia may not be evident until oxygen saturation levels are quite low
For example cyanosis to lips, nail beds, ear lobes
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Does the physical assessment alone provide an adequate picture for good oxygen saturation?
Pulse Oximetry Review
• Pulse dosimeters consist
of a sensor containing a
light source and a photo
detector.
• Technology: based on a
color spectrograph the
photo detector determines
the light absorbed while
passing through the
capillaries then displays
the calculated saturation
levels.
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Factors affecting Oximetry
• Strong ambient light
sources
• Poor circulation
• Cardiac arrest
• Hypothermia
• Shock
• Anemia
• CO poisoning
• Nail polish
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Plethysmograph
• Also know as the O2 sat waveform
• If the waveform is the same with each pulse, then
the numeric value will be accurate.
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Take Home Points
• Oxygen saturation may be
utilized to monitor a patient’s
condition
• Do not restrict oxygen delivery
based on numerical values.
• Remember to treat the patient
not the monitor. If the patient
appears ill and you feel oxygen
will benefit the patient, give
oxygen!
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EtCO2 and SpO2 – Difference??
• EtCo2 measures maximal concentration of carbon dioxide (CO2) at
the end of an exhaled breath.
• SpO2 measures the percentage of hemoglobin binding sites in the
bloodstream occupied by oxygen
• Both are very important tools in the assessment and treatment
decisions for you patient....but...
• EtCo2 is a REAL TIME view of your patients hemodynamic status
while SpO2 can be falsely affected by different factors. Use your
clinical judgement for what’s the best treatment course for your patient
REMEMBER - treat the PATIENT not the MONITOR!!
(have you heard that one before?!)
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Questions??
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