LO6 End Tidal Flashcards
why do we put end tidal on everyone
- Want to see whats going on in the lungs (bronchoconstriction)
- Want to see the effects of treatments
- Capnography (capnometry)
The measurement of carbon dioxide in exhaled breath
- Capnometer
The numeric measure of CO2
- Capnogram
The wave form produced with inspiration & expiration
- ETCO2 define
the level of partial pressure of carbon
-PaCO2
Partial pressure of CO2 in arterial blood
3 things needed for 02
- Cardiac output
- Ventilation: gas exchange at the alveoli wall
- Metabolism: what the cells need to use oxygen
- CO2
is the “Gas of Life” produced from “The fire of life” metabolism
ETCO2
- Provides an immediate, real time, picture of the pt.’s condition
- Capnography will show immediate apnea
- Directly related to the ventilatory status of the pt.
SPO2
- Delayed, SpO2 can show high saturations for several minutes
- SPO2 will not show immediate apnea
- Directly related to oxygenation of the pt.
What else can ETCO2 tell us?
Not only can ETCO2 measure ventilation but . . . .
- It also indirectly measures metabolism & circulation
- An increased metabolism will
increase the production of carbon dioxide & increasing levels on the monitor
- A decreased metabolism will
decrease the amount of CO2 delivered to the lungs & decreases levels on the monitor
Intubated Capnography Patients
- EtCO2 is directly related to the ventilation status & can be used in intubated as well as non-intubated pt.’s
- Capnography in Intubated pt.’s can be used to:
o Verify ETT placement
o Monitor ETT position
o Assess ventilation and treatments
o Evaluate resuscitative efforts during CPR
Non-Intubated Capnography Patients
- Asthma & COPD
- CHF/Pulmonary Edema
- CPAP pt.’s
- Pulmonary Embolus
- Head Injury
Capnography Values
Hyperventilation / Hypocapnia
- > 45mmHg
- Respiratory Acidosis
In-accurate readings may be due to;
- Poor positioning of NC capnofilters
- Obstructed nares
- Mouth breathers
- O2 by mask may lower reading by 10% or more
Increased ETCO2
Due to Increased CO2 Production - Fever - Burns - Hyperthyroidism - Seizure - Bicarbonate Tx - Return Of Spontaneous Circulation - (ROSC) - Release of Tourniquet / Reperfusion - Decreased ETCO2 - Increased CO2 Clearance o Hyperventilation - Exercise - Sick
Decreased ETCO2
Decreased CO2 production - Hypothermia - Sedation - Paralysis Decreased delivery to the lungs - Decreased cardiac output
Normal Waveform
- Straight boxes are good
- Length of wave = Time
- Height of wave = CO2 Level
- CO2 is a result of
Metabolism
Hyperventilation Waveform
CO2 goes down
- Wave forms start getting lower
- Anxiety
- Bronchospasm
- PE
- Increased ventilation
- Remember to look at the trend not just the number
Causes for CO2 going down
- Hypothermia
- Decreased Metabolism
- Decreased Pulmonary perfusion
Hypoventilation Causes
Hypoventilation Causes – CO2 goes up, wave form slows
- Wave forms start getting bigger
- Decreased ventilation
- OD/Intoxication/Sedation
- CNS Dysfunction
- Tiring respiratory pt.
Remember to look at the trend not just the number
High CO2 Waveform
Causes for CO2 going up
- Decrease in respiratory rate
- Decrease in tidal volume
- Increase in metabolic rate
- Rapid rise in body temperature (hyperthermia)
Bronchospasm Waveform
- This wave form can occur in Asthma, COPD, Incomplete Airway Obstruction, Tube kinked or obstructed
o CO2 that is transferred to the alveoli from the bloodstream may take longer to exhale because of the narrowed bronchi.
o This delayed emptying of the alveoli varies in different parts of the lungs.
o This results in the sloping plateau on the capnograph trace, CO2 from parts of the lungs with more severe bronchial narrowing is exhaled later than those parts with less severe narrowing.
what type of shape is bronchospasm
o This represents struggling to exhale & un- even emptying of alveoli
o The pt. hyperventilates to compensate, CO2 drops to below 35
o Asthma worsens, the C02 levels will rise to normal
Emphysema Waveform
- The slope of phase III can be reversed in patients with emphysema where there is marked destruction of alveolar- capillary membranes and reduced gas exchange
Cardiac Asthma & ETCO2
Decrease in airway diameter caused by pulmonary congestion, not bronchoconstriction.
- If the wave form is upright, there is no constriction, the wheezing is caused by the CHF, not the COPD, you might want to withhold the neb treatment.
Pulmonary Embolus
- PE will cause an increase in dead space in the lungs decreasing the alveoli available to off load CO2
- The ETCO2will go down.
- A zero reading from intubated pt
may indicate the ETT is in the esophagus, prolonged down time prior to CPR, or massive PE
Ventilating Pt.’s With ICP
- Finding a Balance
- Hyperventilation = Hypocapnea = Cerebral Ischemia
- Hypoventilation = Hypercapnia = Dialation bleed & pressure
- Keep C02 value of aprox 30 (>35 & not <25 mmHg)
“Bucking” the Tube - “Curare Cleft”
Sedated Intubated Pt.’s
- A notch in the wave form indicates the pt. is starting to arouse from sedation, breathing on their own & may need additional medication
Capnography & Cardiac Output
- Increased Cardiac Output = Increased CO2
- Decreased Cardiac Output = Decreased CO2
