How to Use Capnography During CPR: A Step by Step Guide

Capnography stands as a critical component in the realm of CPR. It provides immediate feedback on the effectiveness of chest compressions and the patient's breathing status. This guide aims to help users understand and integrate capnography seamlessly into CPR procedures.

What is Capnography?

Capnography is a medical monitoring technique that measures the concentration of carbon dioxide (CO2) in exhaled breath. It provides real-time feedback on the patient's ventilation status during CPR. In CPR, capnography helps assess the effectiveness of chest compressions and the patient's breathing effort.

• Capnography devices come in various forms, including mainstream and sidestream configurations.
• Mainstream capnography directly measures CO2 concentration at the airway, while sidestream capnography samples exhaled gases through a sampling tube.
• These devices typically display numeric values for end-tidal CO2 (ETCO2) and graphical waveforms representing CO2 concentration over time.

Importance of Capnography in CPR

Capnography is crucial in CPR as it offers immediate feedback on the quality of chest compressions and the adequacy of ventilation. It helps detect changes in the patient's condition, such as a decrease in cardiac output or the return of spontaneous circulation (ROSC), which is not evident through other means. Capnography alerts rescuers to airway obstructions or misplaced endotracheal tubes during advanced airway management.

How Capnography Works

Capnography analyzes exhaled air to measure CO2 concentration and generate a waveform that reflects the patient's ventilation status. The process involves several key steps:

1. Sampling: When you breathe out, a small sample of your breath is collected using a unique tube or sensor near your mouth or nose.
2. Gas Analysis: This collected air is then analyzed by the capnography device. It looks at how much carbon dioxide (CO2) is in your breath. CO2 is a gas that your body gets rid of when you breathe out.
3. Waveform Generation: The device creates a graph, like a heartbeat monitor, showing the amount of CO2 in your breath over time. It starts at a baseline, goes up, and then levels off.
4. End-Tidal CO2 Measurement: The highest point on the graph is called "end-tidal CO2" (ETCO2). This tells us how much CO2 is in your breath at the very end of breathing out. It helps us understand how well you're breathing.
5. Display: The device shows the ETCO2 number and the graph on a screen. This helps doctors and nurses see if your breathing is okay and if they need to help you breathe better.

Understanding End-Tidal CO2 (ETCO2)

ETCO2, the highest CO2 concentration at the end of exhalation, reflects lung ventilation efficiency and gas exchange. Changes in ETCO2 signal alterations in cardiac output, pulmonary perfusion, or ventilation dynamics. Monitoring ETCO2 helps healthcare providers assess respiratory function and guide interventions for improved patient outcomes.

Studies show higher ETCO2 levels in patients with ROSC and poor outcomes associated with ETCO2 levels <10 mmHg. An abrupt ETCO2 rise indicates ROSC, while CO2 detection post-intubation confirms endotracheal tube placement. However, factors like arrest cause and drug effects influence ETCO2 levels.

Reading Capnography Waveforms

Capnography waveforms consist of three phases: baseline, upstroke, and plateau.

1. Baseline: The baseline phase is the starting point of the waveform. It represents the normal or resting level of CO2 in the breath at the beginning of exhalation. During this phase, the graph maintains a steady and flat line, indicating stable CO2 levels in the respiratory system.
2. Upstroke: Following the baseline phase, the waveform undergoes an upward movement known as the upstroke. This phase occurs as the individual exhales, increasing CO2 concentration in the exhaled air. The upstroke is characterized by a gradual rise in the graph, reflecting the progressive release of CO2 from the lungs into the airway.
3. Plateau: As the upstroke peaks, the waveform transitions into the plateau phase. In this phase, the graph levels horizontally, forming a flat line at the highest point of CO2 concentration during exhalation. The plateau phase represents the end-tidal CO2 (ETCO2).

How to Set Up Capnography equipment before starting CPR?

To set up Capnography during CPR:

1. Ensure the capnography device is powered on and properly calibrated.
2. Connect the device to the patient's airway via an appropriate sampling line or adapter.
3. Calibrate the capnography device according to manufacturer guidelines to ensure accurate CO2 measurements.
4. Establish a baseline ETCO2 value for the patient before initiating CPR.
5. Position the capnography sampling line or sensor securely to minimize air leaks and ensure accurate readings.
6. Confirm proper placement by verifying consistent waveform and numeric values during exhalation.

 How to Use Capnography During CPR

Capnography is an invaluable tool during CPR, providing real-time feedback on ventilation and circulation. Here's how to effectively use capnography during CPR:

1. Placement: Securely attach the capnography device to the patient's airway, either through a nasal cannula, endotracheal tube, or face mask adapter.
2. Monitoring: Continuously monitor the capnography waveform and numeric ETCO2 value throughout CPR. This provides immediate feedback on ventilation effectiveness and circulation.
3. Compression Feedback: Pay attention to changes in the capnography waveform during chest compressions. A sudden decrease or disappearance of the waveform indicates inadequate circulation and the need for adjustment in compression technique or rate.
4. Ventilation Assessment: Assess the ETCO2 value to ensure adequate ventilation. Aim for a target range of 35-40 mmHg. If ETCO2 levels are below this range, consider adjusting ventilation parameters or performing airway interventions.
5. Quality Improvement: Use capnography to improve CPR quality. Ensure consistent waveform presence during compressions and monitor for changes in ETCO2 levels to guide adjustments in CPR technique.
6. Confirmation of ROSC: After achieving Return of Spontaneous Circulation (ROSC), monitor the capnography waveform for sustained ETCO2 levels, indicating restoration of effective circulation.
7. Integration with ACLS Algorithms: Incorporate capnography into Advanced Cardiac Life Support (ACLS) protocols. Use capnography findings to guide decision-making during CPR interventions, such as advanced airway placement or medication administration.

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1. Placement

Ensure proper placement of the capnography device. This is crucial in obtaining accurate readings and optimizing its effectiveness during CPR.

• For intubated patients, secure the endotracheal tube or tracheostomy adapter.
• For non-intubated patients, utilize a nasal cannula or place the capnography sensor between the mask and the face.

Regardless of the patient's intubation status, confirming that the capnography device is securely attached is essential. Check for any potential air leaks around the connection points and address them promptly to maintain the accuracy of CO2 readings. Verify that the sensor is positioned correctly and remains in place throughout CPR procedures to prevent interference with readings.

2. Monitoring

Monitoring end-tidal CO2 (ETCO2) levels during CPR is pivotal for assessing ventilation adequacy. ETCO2 reflects the carbon dioxide (CO2) concentration exhaled, indicating pulmonary perfusion and ventilation effectiveness. Maintaining ETCO2 levels within the target range of 35-40 mmHg signifies optimal gas exchange and circulation.

ETCO2 is a guide for adjusting compression technique and ventilation parameters during CPR. Response to interventions informs further management decisions. Post-ROSC, sustained increases in ETCO2 confirm adequate circulation.

3. Compression Feedback

It's crucial to integrate capnography feedback with chest compression dynamics. Here's how:

• Observation During Compressions: Keep an eye on the capnography waveform while doing chest compressions. Look out for any interruptions or changes in the waveform pattern.
• Interpretation of Changes: If you notice the waveform disappearing or significant alterations during compressions, it might mean there's not enough blood circulation happening. This is a sign that adjustments are needed.
• Actionable Adjustments: To improve perfusion pressure and enhance blood flow throughout the body, consider tweaking your compression technique, depth, or rate. These adjustments optimize the effectiveness of CPR efforts.

4. Ventilation Assessment

Check the ETCO2 level regularly to ensure it falls within the 35-40 mmHg target range. This range indicates adequate ventilation. If the ETCO2 level deviates from this range, it could signal various issues:

• Hypoventilation: The patient isn't receiving enough ventilation.
• Hyperventilation: The patient is receiving too much ventilation.
• Changes in Cardiac Output: The heart's pumping effectiveness is altered.

Adjust ventilation parameters like tidal volume or respiratory rate based on ETCO2 readings to optimize oxygenation.

5. Quality Improvement

Capnography serves as a quality assurance tool during CPR. Ensure the capnography waveform remains consistently visible throughout compression cycles, indicating effective chest compressions and adequate circulation.

The capnography waveform confirms that blood flows through the lungs during compressions, optimizing oxygenation and CO2 removal. Any deviations from the expected waveform pattern should be addressed promptly. This includes compression technique, depth, or rate changes to maintain optimal resuscitation efforts.

6. Confirmation of ROSC

Confirmation of ROSC involves continued monitoring of the capnography waveform and ETCO2 levels post-CPR. Sustained and stable capnography waveforms and ETCO2 within the target range of 35-40 mmHg confirm effective circulation. This guides ongoing management decisions, ensuring optimal patient care.

7. Integration with ACLS Algorithms

Integrating capnography data into Advanced Cardiac Life Support (ACLS) algorithms enhances patient care. Here's how:

• Advanced Airway Management: Use capnography findings to guide decisions regarding advanced airway management, such as endotracheal intubation or supraglottic airway placement.
• Medication Administration: Utilize capnography data to guide the administration of medications during resuscitation efforts. Capnography findings inform the timing and dosage of medications, ensuring appropriate pharmacological interventions based on patient response.
• Defibrillation Timing: Incorporate capnography findings into the timing of defibrillation interventions. Capnography helps assess circulation status and guides decisions on when to deliver defibrillation shocks, optimizing the effectiveness of electrical therapy.

Normal vs. Abnormal Waveforms

Normal capnography waveforms display a smooth, gradual rise followed by a plateau phase. This pattern indicates effective ventilation and adequate perfusion, reflecting proper lung function and stable respiratory status.

In contrast, abnormal waveforms exhibit irregularities such as sudden drops, fluctuations, or an absence of the plateau phase. These irregularities suggest potential issues with ventilation or perfusion, such as airway obstruction, inadequate circulation, or equipment malfunction. 

Troubleshooting Common Issues

Capnographs sometimes present issues that affect their accuracy. Here are some common problems and how to troubleshoot them:

1. Sensor Displacement: Sensor displacement leads to inaccurate readings. Ensure the sensor is securely placed and properly aligned. Reposition the sensor if necessary to maintain accurate readings.

2. Airway Obstructions: Blockages in the airway affect capnography readings. Regularly check for and clear any obstructions in the airway to ensure a clear path for measurement.

3. Sampling Line Kinks: Kinks or bends in the sampling line disrupt the flow of air and skew readings. Inspect the sampling line for any kinks or bends. Straighten or replace the sampling line if needed to ensure a smooth airflow.

4. Environmental Factors: High ambient CO2 levels interfere with accurate readings. Be mindful of the surrounding environment and any potential sources of elevated CO2. Ensure that external CO2 sources are minimized or accounted for in the readings.

5. Equipment Calibration: Improperly calibrated equipment provides false readings. Regularly verify that the capnography equipment is correctly calibrated according to the manufacturer's guidelines. Recalibrate the equipment if necessary to maintain accuracy.

Integrating Capnography with Other Monitoring Techniques

Effective patient monitoring often requires integrating multiple techniques to view a patient's status comprehensively. When combined with other monitoring methods, capnography significantly enhances patient assessment and management.

Combining Capnography with Pulse Oximetry

Capnography measures CO2 levels in exhaled air, offering insights into ventilation status, while pulse oximetry measures blood oxygen saturation, indicating oxygenation status.

Using both tools together provides a comprehensive view of respiratory function, allowing healthcare providers to detect issues like hypoventilation or apnea earlier than pulse oximetry alone. This combined approach enables more precise interventions, better ventilator adjustments, and effective monitoring of treatments, ultimately enhancing patient care.

How Capnography Complements Visual and Tactile Assessments

Capnography offers objective data on ventilation and circulation, which is crucial for accurate patient evaluation, especially in emergencies where visual and tactile assessments might be subjective. Integrating capnography into CPR protocols enhances resuscitation by indicating the return of spontaneous circulation (ROSC), thus guiding the team more effectively.

By combining capnography with traditional assessment methods, healthcare providers make more informed decisions, improving patient outcomes through continuous monitoring that helps identify trends and prevent complications.

The Role of Capnography in Different Resuscitation Scenarios

Capnography's utility extends beyond typical cardiac arrest situations to include specialized scenarios such as drowning and drug overdose.

• In drowning cases, capnography aids in assessing the effectiveness of rescue breaths and detecting potential complications like aspiration.
• In drug overdose situations, capnography helps monitor respiratory status and guide interventions, especially in opioid-related respiratory depression.

Pediatric vs. Adult Capnography

Capnography is a valuable tool for monitoring respiratory status in both pediatric and adult patients. Still, its application and interpretation differ between these two groups due to physiological and developmental variations.

Pediatric Capnography:

• Age-Specific Norms: Pediatric patients have different normal ranges for end-tidal CO2 (EtCO2) that vary with age.
• Waveform Characteristics: Faster respiratory rates and smaller tidal volumes in children result in less defined and more variable waveforms.
• Equipment Adaptations: Specialized smaller sampling lines and sensors are needed to ensure accuracy.
• Clinical Considerations: Rapid changes in respiratory status in children make capnography essential for quickly identifying issues like hypoventilation and apnea.

Adult Capnography:

• Established Norms: Adults have a standard EtCO2 range of 35-45 mmHg.
• Stable Waveforms: More stable and consistent waveforms due to slower respiratory rates and larger tidal volumes.
• Standard Equipment: Regular capnography equipment is generally sufficient for accurate readings.
• Clinical Applications: Widely used in anesthesia, critical care, and emergency medicine for monitoring ventilation, guiding intubation, and assessing resuscitation.

How does capnography help in monitoring CPR effectiveness?

Capnography helps monitor CPR effectiveness by providing real-time feedback on ventilation and circulation during CPR. It measures end-tidal carbon dioxide (EtCO2) levels, indicating the adequacy of chest compressions and perfusion.

Capnography is increasingly recognized as vital in assessing CPR effectiveness, and recent ACLS guidelines have endorsed it. Studies show PETCO2 correlates with cardiac output, indicating ROSC. It also confirms endotracheal tube placement and potentially predicts survival post-cardiac arrest.

How does capnography improve the outcomes of CPR?

Capnography significantly enhances the effectiveness of CPR by providing real-time feedback on the patient's ventilation and circulation status. It allows healthcare providers to monitor the exhaled carbon dioxide (EtCO2) levels, which correlate with cardiac output and perfusion.

During CPR, capnography detects the return of spontaneous circulation (ROSC) earlier than other traditional methods, enabling prompt adjustments to CPR techniques and interventions.

Additionally, capnography helps identify and correct issues such as airway obstructions, improper ventilation, or ineffective chest compressions, ultimately improving the quality of resuscitation efforts and patient outcomes.

Can capnography be used in all CPR situations?

Capnography is a valuable adjunct to CPR and is recommended for use in all resuscitation situations, including cardiac arrest, respiratory arrest, and during advanced airway management (e.g., intubation). It provides real-time feedback on ventilation and circulation status, guiding CPR interventions and optimizing patient care.

However, in some low-resource or prehospital settings where capnography equipment not be readily available, traditional methods such as pulse checks and clinical assessment remain essential components of CPR. Nonetheless, whenever feasible, integrating capnography into CPR protocols enhances the quality of resuscitation efforts and improves patient outcomes.

What do normal and abnormal capnography waveforms look like during CPR?

Normal capnography waveforms during CPR exhibit consistent peaks and valleys, indicating effective chest compressions and circulation. Abnormal waveforms appear flat or erratic, suggesting inadequate chest compressions or airway obstructions. Monitoring waveform patterns alongside EtCO2 values helps clinicians interpret capnography data accurately to make informed clinical decisions.

How can capnography readings influence the adjustments of CPR techniques?

Capnography readings provide real-time feedback on CPR effectiveness, guiding adjustments in compression rate, depth, and airway management. Increasing EtCO2 levels indicate improved perfusion and suggest effective chest compressions while decreasing levels prompt interventions such as airway repositioning or advanced life support measures.

Can capnography be used for all patients during CPR, including children?

Yes, capnography is valuable for all patients during CPR, including children. However, a study examining capnography use in pediatric emergency departments found that despite its importance and recommendations, capnography was documented in only 38% of intubated patients and 13% of those undergoing CPR.

The study also noted decreased capnography use following the 2010 AHA guidelines. Interestingly, capnography use correlated with longer CPR duration and return of spontaneous circulation. These findings highlight the necessity for enhanced education and implementation strategies to improve the utilization of capnography in pediatric emergency care. Proper equipment sizing and pediatric-specific protocols enhance the effectiveness of capnography in pediatric CPR.

What are the latest advancements in capnography technology for CPR?

The latest advancements in capnography technology for CPR focus on improving portability, usability, and integration with other monitoring systems.

• Portability: Devices are smaller and lighter, aiding use in various settings.
• Usability: They're more user-friendly, integrating better into CPR protocols.
• Wireless Monitoring: Real-time data transmission improves communication among providers.
• Data Interpretation: Software enhances accuracy, providing predictive analytics for better CPR decisions.
• Innovative Applications: Ongoing research explores advanced sensors and AI integration, refining resuscitation strategies.

What training is required to effectively use capnography during CPR?

Proficiency in capnography during CPR requires comprehensive training in equipment operation, waveform interpretation, and integration into resuscitation protocols. Educational programs and certifications, such as Basic Life Support Courses and Advanced Cardiac Life Support, offer essential training in capnography utilization for healthcare professionals. Ongoing education and simulation-based training ensure competency in utilizing capnography effectively during CPR scenarios.

Sources:

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Sandroni C, De Santis P, D'Arrigo S. Capnography during cardiac arrest. Resuscitation. 2018 Nov;132:73-77. doi: 10.1016/j.resuscitation.2018.08.018. Epub 2018 Aug 22. PMID: 30142399.

Kodali BS, Urman RD. Capnography during cardiopulmonary resuscitation: Current evidence and future directions. J Emerg Trauma Shock. 2014 Oct;7(4):332-40. doi: 10.4103/0974-2700.142778. PMID: 25400399; PMCID: PMC4231274.