What does end-tidal CO2 tell you

End-tidal carbon dioxide (ETco2) monitoring provides valuable information about CO2 production and clearance (ventilation). Also called capnometry or capnography, this noninvasive technique provides a breath-by-breath analysis and a continuous recording of ventilatory status.

Why is end tidal CO2 important?

In critical care, End Tidal CO2 monitoring is used to assess adequacy of circulation to the lungs, which provides clues about circulation to the rest of the body. Low EtCO2 with other signs of shock indicates poor systemic perfusion, which can be caused by hypovolemia, sepsis or dysrhythmias.

What does ETCO2 determine?

End-tidal CO2 (EtCO2) monitoring is a measure of metabolism, perfusion, and ventilation. In the ED, we typically think of a EtCO2 as a marker of perfusion and ventilation.

What does an increase in end tidal CO2 mean?

ETCO2 is the amount of carbon dioxide (CO2) in exhaled air, which assesses ventilation. So a high ETCO2 is a good sign of good ventilation, while low ETCO2 is bad sign that represents hypoventilation.

When end-tidal CO2 is low?

3. Think perfusion, metabolic or psychological problem when ETCO2 is low. Other respiratory conditions can cause a low ETCO2 reading or hypocapnea. With pulmonary embolism, a blocked pulmonary artery causes less CO2-rich blood to return to the lungs, and less CO2 is released with each breath.

What does a sloped upstroke on a Capnogram indicate?

Prolongation or slanting of the expiratory upstroke phase II occurs when there is obstruction to expiratory gas flow (e.g., asthma, bronchospasm, obstructive pulmonary disease, and kinked endotracheal tube,1-9 or in the presence of leaks in the breathing system.

What does a flat plateau on a Capnogram mean?

In phase 3 (C to D on the capnogram), all of the gas passing by the CO2 sensor is alveolar gas which causes the capnograph to flatten out. This is often called the Alveolar Plateau. The End Tidal CO2 value displayed on the monitor is considered the value taken at end exhalation.

Why is it called curare cleft?

This “curare cleft,” named after the first primitive neuromuscular blocker, presents as a miniscule notch in the alveolar plateau (Phase III). When you notice curare clefts in your capnography waveform, you only have 2-3 minutes to re-administer the neuromuscular blockade before the patient comes out of paralysis.

What angle is the end-tidal CO2 measured?

In a healthy patient, the angle formed (α) from Phase II to Phase III is approximately 110 degrees, and the angle formed between Phase III and 0 (β) is typically about 90 degrees. When asthmatics present with a severe attack, their waveform changes in such a manner that it begins to resemble a shark fin.

How does a Capnograph measure CO2?

Capnography uses infrared waves to measure CO2. Infrared waves are waves that are invisible to the eye and have a lower frequency than visible light. The frequency is below red light, which is why it is called “infra” red. Infrared is absorbed by gases that have “two or more different atoms.

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What characteristics are observed in a normal Capnogram?

A normal capnogram for patients of all ages is characterized by a set of specific elements: it includes 4 distinct phases (Figure 1), the CO2 concentration starts at zero and returns to zero (ie, there is no rebreathing of CO2), a maximum CO2 concentration is reached with each breath (ie, ETCO2), the amplitude depends …

What should end-tidal CO2 be kPa?

Current guidance recommends an end- tidal carbon dioxide (ETCO2) of 4.0–4.5 kPa (30.0– 33.8 mm Hg) to achieve a low- normal arterial partial pressure of CO2 (PaCO2), and reduce secondary brain injury.

What is the main determinant of end-tidal carbon dioxide measurement during CPR?

It is most reliably measured using waveform capnography, where the visualization of the actual CO2 waveform during ventilation ensures accuracy of the measurement. During low-flow states with relatively fixed minute ventilation, pulmonary blood flow is the primary determinant of ETCO2 .

Why do we measure CO2 in patients?

CO2 values correlate reliably with the patient’s ventilation, and its measure is crucial in order to affirm hypo- or hyperventilation of the patient.

What end-tidal CO2 reading level indicates that the patient likely has Rosc?

(1) A 2015 meta-analysis of ETCO2 values associated with ROSC showed, on average, patients with ROSC after CPR had an average ETCO2 level of 25 mmHg, significantly higher than the current recommended 10 mmHg threshold.

Why is end-tidal CO2 or capnography recommended as part of high quality cardiac resuscitation?

ETCO2 provides feedback on how effective compressions are at perfusing vital organs. Both are important to guide treatment, and both should be applied as early as possible. A higher ETCO2 reading during resuscitation correlates with improved cardiac output and patient outcomes.