A capnograph is a critical medical device primarily used to assess respiratory health. It measures the concentration of CO₂ in exhaled breath and is commonly referred to as an end-tidal CO₂ (EtCO2) monitor. This device provides real-time measurements along with graphical waveform displays (capnograms), offering valuable insights into a patient’s ventilatory status.
How Does Capnography Work?
Here’s how it works in the body: oxygen enters the bloodstream through the lungs and supports the body’s metabolic processes. As a byproduct of metabolism, carbon dioxide is produced, transported back to the lungs, and then exhaled. Measuring the amount of CO₂ in exhaled air provides important information about a patient’s respiratory and metabolic function.
How a Capnograph Measures CO2?
A capnograph monitor measures exhaled breath by displaying the partial pressure of CO₂ in waveform format on an x- and y-axis grid. It displays both waveforms and numerical measurements. A normal end-tidal CO₂ (EtCO₂) reading typically ranges from 30 to 40 mmHg. If a patient’s EtCO2 falls below 30 mmHg, it may indicate issues such as endotracheal tube malfunction or other medical complications that affect oxygen intake.
Two Primary Methods for Exhaled Gas Measurement
Mainstream EtCO2 Monitoring
In this method, an airway adapter with an integrated sampling chamber is placed directly in the airway between the breathing circuit and the endotracheal tube.
Sidestream EtCO2Monitoring
The sensor is located within the main unit, away from the airway. A small pump continuously aspirates exhaled gas samples from the patient through a sampling line to the main unit. The sampling line can be connected to a T-piece at the endotracheal tube, an anesthesia mask adapter, or directly to the nasal cavity via a sampling nasal cannula with nasal adapters.
There are also two main types of monitors.
One is a portable dedicated EtCO₂ capnograph, which focuses solely on this measurement.
The other is an EtCO₂ module integrated into a multiparameter monitor, which can measure multiple patient parameters at once. Bedside monitors, operating room equipment, and EMS defibrillators often include EtCO₂ measurement capabilities.
What are the Clinical Applications of Capnograph?
- Emergency Response: When a patient is experiencing respiratory arrest or cardiac arrest, EtCO2 monitoring helps medical staff quickly assess the patient’s respiratory status.
- Continuous Monitoring: For critically ill patients at risk of sudden respiratory deterioration, continuous end-tidal CO₂ monitoring provides real-time data to detect and respond to changes promptly.
- Sedation Procedure: Whether it’s minor or major surgery, when a patient is sedated, EtCO2 monitoring ensures that the patient maintains adequate ventilation throughout the procedure.
- Pulmonary Function Assessment: For patients with chronic conditions like sleep apnea and chronic obstructive pulmonary disease (COPD), capnographs assist in evaluating their lung function.
Why is EtCO₂ Monitoring Considered a Standard of Care?
Capnography is now widely recognized as a best standard of care in many clinical settings. Leading medical organizations and regulatory bodies—such as the American Heart Association (AHA) and the American Academy of Pediatrics (AAP)—have incorporated capnography into their clinical guidelines and recommendations. In most cases, it is considered an essential component of patient monitoring and respiratory care.
American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation (CPR) and Emergency Cardiovascular Care (ECC) of Pediatric and Neonatal Patients: Neonatal Resuscitation Guidelines
Part 8: Adult Advanced Cardiovascular Life Support
8.1: Adjuncts for Airway Control and Ventilation
Advanced Airways – Endotracheal Intubation Continuous waveform capnography is recommended in addition to clinical assessment as the most reliable method of confirming and monitoring correct placement of an endotracheal tube (Class I, LOE A). Providers should observe a persistent capnographic waveform with ventilation to confirm and monitor endotracheal tube placement in the field, in the transport vehicle, on arrival at the hospital, and after any patient transfer to reduce the risk of unrecognized tube misplacement or displacement. Effective ventilation through a supraglottic airway device should result in a capnograph waveform during CPR and after ROSC (S733).
EtCO2 Monitoring vs SpO2 Monitoring
Compared to pulse oximetry (SpO₂), EtCO2 monitoring offers more distinct advantages. Because EtCO₂ provides real-time insight into alveolar ventilation, it responds more rapidly to changes in respiratory status. In cases of respiratory compromise, EtCO₂ levels fluctuate almost immediately, whereas drops in SpO₂ may lag by several seconds to minutes. Continuous EtCO2 monitoring enables clinicians to detect respiratory deterioration earlier, offering critical lead time for timely intervention before oxygen saturation declines.
EtCO2 Monitoring
EtCO2 monitoring provides real-time evaluation of respiratory gas exchange and alveolar ventilation. EtCO2 levels respond rapidly to respiratory abnormalities and are not significantly influenced by supplemental oxygen. As a non-invasive monitoring modality, EtCO2 is widely employed in various clinical environments.
Pulse Oximetry Monitoring
Pulse oximetry (SpO₂) monitoring utilizes a non-invasive finger sensor to measure blood oxygen saturation levels, enabling effective detection of hypoxemia. This technique is user-friendly and well-suited for continuous bedside monitoring of non-critically ill patients.
Clinical Application | SpO₂ | EtCO2 | |
Mechanical Ventilator | Esophageal intubation of endotracheal tube | Slow | Rapid |
Bronchial intubation of endotracheal tube | Slow | Rapid | |
Respiratory arrest or loose connection | Slow | Rapid | |
Hypoventilation | x | Rapid | |
Hyperventilation | x | Rapid | |
Decreased oxygen flow rate | Rapid | Slow | |
Anesthesia Machine | Soda lime exhaustion/rebreathing | Slow | Rapid |
Patient | Low inspired oxygen | Rapid | Slow |
Intrapulmonary shunt | Rapid | Slow | |
Pulmonary embolism | x | Rapid | |
Malignant hyperthermia | Rapid | Rapid | |
Circulatory arrest | Rapid | Rapid |
How to Choose CO₂ Accessories and Consumables?
North America currently dominates the market, accounting for about 40% of global revenue, while the Asia-Pacific region is expected to register the fastest growth, with a forecasted CAGR of 8.3% during the same period. Leading global patient monitor manufacturers—such as Philips (Respironics), Medtronic (Oridion), Masimo, and Mindray—are continuously innovating in EtCO2 technology to meet the evolving needs of anesthesia, critical care, and emergency medicine.
To meet clinical requirements and improve workflow efficiency for medical staff, MedLinket focuses on developing and producing high-quality consumables, such as sampling lines, airway adapters, and water traps. The company is dedicated to providing healthcare facilities with reliable consumable solutions for both mainstream and sidestream monitoring, which are compatible with many leading patient monitor brands, contributing to the development of the respiratory monitoring field.
Mainstream etco2 sensors and airway adapters are the most common accessories and consumables for mainstream monitoring.
For sidestream monitoring,to consider include,sidestream sensors,and water traps,CO2 Sampling line,depending on your setup and maintenance needs.
Water Trap Series |
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OEM Manufacturer & Models |
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OEM # |
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Descriptions |
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Compatible Mindray (China) | ||||||||||
For BeneView, iPM, iMEC, PM, MEC-2000 series monitors, PM-9000/7000/6000 series, BeneHeart defibrillator | ![]() |
115-043022-00 (9200-10-10530) |
RE-WT001A | Dryline water trap, Adult/Pediatirc for dual-slot module, 10pcs/box | ||||||
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115-043023-00 (9200-10-10574) |
RE-WT001N | Dryline water trap, Neonatal for dual-slot module, 10pcs/box | |||||||
For BeneVision, BeneView series monitors | ![]() |
115-043024-00 (100-000080-00) |
RE-WT002A | Dryline II water trap, Adult/Pediatirc for single-slot module, 10pcs/box | ||||||
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115-043025-00 (100-000081-00) |
RE-WT002N | Dryline II water trap, Neonatal for single-slot module, 10pcs/box | |||||||
Compatible GE | ||||||||||
GE Solar Sidestream EtCO₂ Module, GE MGA-1100 Mass Spectrometer GE Advantage System, EtCO₂ Sampling Systems | ![]() |
402668-008 | CA20-013 | Single patient use 0.8 micron Fitter, standard Luer Lock, 20pcs/box | ||||||
GE Healthcare gventilator, monitor, anesthesia machine with E-miniC gas module | ![]() |
8002174 | CA20-053 | Internal Container volume is > 5.5mL, 25pcs/box | ||||||
Compatible Drager | ||||||||||
Compatible Drager Babytherm 8004/8010 Babylog VN500 ventilator | ![]() |
6872130 | WL-01 | Single patient use Waterlock, 10pcs/box | ||||||
Compatible Philips | ||||||||||
Compatible Module:Philips – IntelliVue G5 | ![]() |
M1657B / 989803110871 | CA20-008 | Philips water trap, 15pcs/box | ||||||
Compatible Philips | ![]() |
CA20-009 | Philips water trap Rack | |||||||
Compatible Module:Philips – IntelliVue G7ᵐ | ![]() |
989803191081 | WL-01 | Single patient use Waterlock, 10pcs/box |
CO2 Sampling line |
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Patient connector |
Patient connector picture |
Instrument interface |
Instrument interface picture |
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Luer Plug | ![]() |
Luer plug | ![]() |
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T-type sampling line | ![]() |
Philips(Respironics) plug | ![]() |
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L-type sampling line | ![]() |
Medtronic(Oridion) plug | ![]() |
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Nasal sampling line | ![]() |
Masimo plug | ![]() |
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Nasal/Oral sampling line | ![]() |
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Post time: Jun-03-2025