Capnography
The measurement of carbon dioxide concentration in exhaled breath, used to monitor ventilation, confirm airway placement, and assess perfusion. Includes both continuous waveform monitoring and single-use colorimetric detection products such as needle decompression indicator kits and CapnoSpot.
In the Field
Capnography is what tells you whether the airway you placed is in the right spot, whether the patient is actually breathing, and whether the chest decompression you performed actually got air. It comes in two forms. Waveform capnography is the continuous monitor with a screen, used by paramedics and tactical paramedics for ongoing assessment. Colorimetric CO2 detection is the single-use cartridge that changes color in the presence of CO2, used as a yes-or-no confirmation tool. The colorimetric version is what shows up in needle decompression indicator kits and products like CapnoSpot, where the question is simply "did this procedure access an air-containing space" rather than "what is the patient's exact CO2 trend over time." For procurement, both forms have a place. Waveform capnography belongs in advanced aid bags and on ALS units. Colorimetric detection belongs in IFAKs and provider kits as a low-cost confirmation tool that does not require electronics.
Common Mistake
Reading only the end-tidal CO2 number from a waveform capnograph without interpreting the waveform shape, or relying on a colorimetric detector for ongoing monitoring when its function is single-point confirmation only.
Technical Detail
Capnography is the measurement of carbon dioxide (CO2) concentration in exhaled breath. The two major capnography categories used in tactical and emergency medicine are waveform capnography (continuous electronic monitoring with graphical display) and colorimetric CO2 detection (single-use chemical indicators that change color in the presence of CO2).
How CO2 measurement reveals clinical information. CO2 is produced by cellular metabolism, transported by the blood to the lungs, and exhaled. The presence and amount of CO2 in exhaled breath reflects the integrated function of:
Cellular metabolism producing CO2.
Cardiovascular system delivering CO2-containing blood to the lungs (perfusion).
Respiratory system moving air in and out (ventilation).
Airway integrity allowing exhaled gas to reach the measurement sensor.
A device or indicator that detects CO2 confirms that air is moving from a perfused alveolar space through a patent airway. This is why CO2 detection is the gold standard for confirming airway placement and patency.
WAVEFORM CAPNOGRAPHY
Waveform capnography continuously measures CO2 using infrared spectroscopy and displays both a numerical end-tidal CO2 value (EtCO2, the CO2 concentration at the end of exhalation) and a continuous waveform showing CO2 concentration over time.
Normal values. Normal end-tidal CO2 in healthy patients is approximately 35 to 45 mmHg (about 5 percent CO2 by volume). The normal waveform shows a characteristic shape: sharp rise during exhalation, flat plateau, sharp drop with inhalation.
Clinical applications of waveform capnography:
Airway placement confirmation. After endotracheal tube or supraglottic airway placement, waveform capnography confirms the device is in the airway rather than the esophagus. CO2 is detected only from a properly placed airway connected to functioning lungs.
Continuous ventilation monitoring. The waveform shows whether the patient is breathing, the rate of breathing, the depth of breathing, and whether breathing is effective. Loss of waveform indicates apnea, airway obstruction, displaced airway device, or cardiac arrest.
Perfusion assessment. End-tidal CO2 reflects pulmonary blood flow. In low cardiac output states (hemorrhagic shock, cardiac arrest), CO2 delivery to the lungs falls and end-tidal CO2 drops. Capnography functions as a perfusion indicator alongside its ventilation function.
CPR quality monitoring. During cardiac arrest resuscitation, end-tidal CO2 reflects chest compression effectiveness. Higher values during CPR indicate better perfusion. A sudden rise in end-tidal CO2 during CPR can indicate return of spontaneous circulation (ROSC).
Bronchospasm recognition. The waveform shape changes characteristically with bronchospasm (asthma, anaphylaxis), showing a "shark fin" appearance instead of the normal sharp rise and plateau.
Sedation and respiratory depression monitoring. Waveform capnography detects respiratory depression earlier than pulse oximetry, where breathing slows or stops before oxygen saturation falls.
Waveform interpretation. The waveform shape carries diagnostic information beyond the numerical value:
Normal waveform. Sharp rise, flat plateau, sharp drop.
Loss of waveform. No CO2 detected. Indicates apnea, obstruction, displaced airway, equipment failure, or arrest.
Sloped or shark-fin waveform. Gradual rise rather than sharp rise. Indicates bronchospasm or partial airway obstruction.
Sudden drop. Sudden falloff of EtCO2 indicates loss of perfusion (cardiac arrest) or loss of airway connection (tube displacement, circuit disconnection).
Reading the waveform is the skill that distinguishes proficient capnography use from simple number-watching.
Equipment. Waveform capnography requires:
A capnography monitor (standalone or integrated into a multi-parameter monitor).
A sampling line (sidestream sampling) or in-line sensor (mainstream sampling) connected to the airway.
Power supply (battery for portable units, AC for fixed units).
Modern portable cardiac monitors used in EMS and tactical paramedic settings (Zoll X Series, LifePak 15, and similar) typically include integrated capnography capability.
COLORIMETRIC CO2 DETECTION
Colorimetric CO2 detectors are single-use chemical indicators that change color in the presence of CO2. They provide a yes-or-no answer to the question "is CO2 present at this point?" without requiring electronics, batteries, or training in waveform interpretation.
How they work. Colorimetric detectors contain a chemical (typically a pH-sensitive dye) that changes color when exposed to the acidic conditions produced by CO2. The detector is exposed to the gas being tested. If CO2 is present at sufficient concentration, the indicator changes color (typically from purple to yellow). If no CO2 is present, the indicator does not change.
Endotracheal tube confirmation. The original and most established colorimetric CO2 application. After endotracheal intubation, a colorimetric detector is placed between the endotracheal tube and the bag-valve-mask. Several breaths through the detector confirm CO2 presence (yellow color) for tracheal placement, or absence (purple) for esophageal placement. Common product examples include the EasyCap and StatCO2.
NEEDLE DECOMPRESSION INDICATOR KITS
Needle decompression indicator kits combine a needle decompression catheter with a colorimetric CO2 indicator, addressing a specific procedural confirmation problem.
The procedural problem. When performing needle decompression for suspected tension pneumothorax, the provider inserts a large-bore catheter through the chest wall into the pleural space. Confirming successful access to the pleural space has historically relied on:
Audible "rush of air" upon needle entry into a pressurized pleural space.
Tactile feeling of decreased resistance as the needle passes through the pleura.
Clinical improvement of the patient (relief of respiratory distress, hemodynamic improvement).
These confirmation methods have known limitations:
Background noise (ongoing tactical operation, helicopter, vehicle) can mask audible rush of air.
Tactile feedback is operator-dependent and can be unreliable in stressful conditions.
Clinical improvement may not occur if the indication was incorrect or if other factors are dominant.
In some cases, the needle does not actually enter the pleural space due to chest wall thickness, angle of insertion, or anatomic variation, but the operator perceives entry. The patient does not improve and additional intervention is required.
The colorimetric solution. A needle decompression indicator kit incorporates a colorimetric CO2 detector into the catheter assembly. When the needle successfully enters the pleural space and air begins to flow out through the catheter, the air contains some CO2 (from gas exchange with surrounding lung tissue, or from a hemopneumothorax containing carbonic compounds). The colorimetric indicator changes color, providing visual confirmation that air is actually flowing out of the chest cavity through the catheter.
The indicator confirms what the operator might otherwise have to infer. In tactical conditions where audible and tactile cues may be unreliable, the visual color change provides an additional verification that the procedure was successful.
Examples of commercial needle decompression indicator products include integrated catheter-and-indicator kits from various manufacturers. The category is relatively recent in tactical medical procurement and continues to evolve.
CAPNOSPOT
CapnoSpot is a brand of colorimetric CO2 detector designed for compact, low-cost confirmation applications. The device is a small adhesive or in-line indicator that changes color in the presence of CO2. CapnoSpot products are positioned for several use cases:
Endotracheal tube and supraglottic airway confirmation in field settings where waveform capnography is not available.
Verification of bag-valve-mask ventilation effectiveness.
IFAK-level inclusion as a low-cost confirmation tool.
Tactical scenarios where electronic capnography equipment is impractical.
The value proposition is simple, low-cost, electronics-free confirmation of CO2 presence at a specific point. CapnoSpot does not provide continuous monitoring, waveform analysis, or numerical readings. It answers a single yes-or-no question.
For procurement officers, CapnoSpot and similar colorimetric products fit into kit configurations where waveform capnography would be excessive (basic IFAKs, austere kits, training scenarios) but where some form of CO2 confirmation is desired.
WAVEFORM VS. COLORIMETRIC: WHEN TO USE EACH
Each capnography category fits different operational contexts:
Waveform capnography is appropriate for:
Tactical paramedic and SWAT medic aid bags.
Air medical and critical care transport.
ALS-level EMS units.
Hospital and trauma center settings.
Any scenario requiring continuous monitoring, waveform interpretation, or trend analysis.
Colorimetric detection (including needle decompression indicator kits and CapnoSpot) is appropriate for:
IFAKs and basic provider kits where waveform capnography is impractical.
Single-use confirmation applications (airway placement, needle decompression, ventilation effectiveness).
Austere and prolonged field care environments without reliable power.
Cost-sensitive deployments where waveform capnography is not justified.
Training and simulation scenarios.
Many tactical medical programs use both. Waveform capnography in the aid bag for sustained monitoring, plus colorimetric devices in IFAKs and as backups for specific procedural confirmations.
Provider scope. Capnography use is a provider-level skill at higher tiers:
Waveform capnography interpretation. Paramedic, tactical paramedic, and higher provider levels with specific training.
Colorimetric CO2 detection. Generally usable at lower training tiers with appropriate instruction. Single-use indicators are simpler to use than electronic monitors.
Procurement implications. Capnography capability across the kit hierarchy:
IFAKs. Colorimetric devices (CapnoSpot or equivalent) for cost-effective single-point confirmation.
Aid bags. Waveform capnography integrated with the cardiac monitor or as a dedicated capnograph. Spare colorimetric devices for backup confirmation.
Needle decompression. Indicator kits or stand-alone colorimetric devices to support procedural confirmation.
Training. Both waveform interpretation (provider levels) and colorimetric use (broader population). Skill maintenance through regular practice.
Documentation. Capnography findings (numerical values, waveform changes, color confirmation) documented in patient care reports.
Capnography in all its forms is one of the most useful assessment categories in modern field medicine. The shift over the past two decades from "no field capnography" to "capnography as standard for advanced airway management" has substantially improved the safety and reliability of tactical medical operations.
How CO2 measurement reveals clinical information. CO2 is produced by cellular metabolism, transported by the blood to the lungs, and exhaled. The presence and amount of CO2 in exhaled breath reflects the integrated function of:
Cellular metabolism producing CO2.
Cardiovascular system delivering CO2-containing blood to the lungs (perfusion).
Respiratory system moving air in and out (ventilation).
Airway integrity allowing exhaled gas to reach the measurement sensor.
A device or indicator that detects CO2 confirms that air is moving from a perfused alveolar space through a patent airway. This is why CO2 detection is the gold standard for confirming airway placement and patency.
WAVEFORM CAPNOGRAPHY
Waveform capnography continuously measures CO2 using infrared spectroscopy and displays both a numerical end-tidal CO2 value (EtCO2, the CO2 concentration at the end of exhalation) and a continuous waveform showing CO2 concentration over time.
Normal values. Normal end-tidal CO2 in healthy patients is approximately 35 to 45 mmHg (about 5 percent CO2 by volume). The normal waveform shows a characteristic shape: sharp rise during exhalation, flat plateau, sharp drop with inhalation.
Clinical applications of waveform capnography:
Airway placement confirmation. After endotracheal tube or supraglottic airway placement, waveform capnography confirms the device is in the airway rather than the esophagus. CO2 is detected only from a properly placed airway connected to functioning lungs.
Continuous ventilation monitoring. The waveform shows whether the patient is breathing, the rate of breathing, the depth of breathing, and whether breathing is effective. Loss of waveform indicates apnea, airway obstruction, displaced airway device, or cardiac arrest.
Perfusion assessment. End-tidal CO2 reflects pulmonary blood flow. In low cardiac output states (hemorrhagic shock, cardiac arrest), CO2 delivery to the lungs falls and end-tidal CO2 drops. Capnography functions as a perfusion indicator alongside its ventilation function.
CPR quality monitoring. During cardiac arrest resuscitation, end-tidal CO2 reflects chest compression effectiveness. Higher values during CPR indicate better perfusion. A sudden rise in end-tidal CO2 during CPR can indicate return of spontaneous circulation (ROSC).
Bronchospasm recognition. The waveform shape changes characteristically with bronchospasm (asthma, anaphylaxis), showing a "shark fin" appearance instead of the normal sharp rise and plateau.
Sedation and respiratory depression monitoring. Waveform capnography detects respiratory depression earlier than pulse oximetry, where breathing slows or stops before oxygen saturation falls.
Waveform interpretation. The waveform shape carries diagnostic information beyond the numerical value:
Normal waveform. Sharp rise, flat plateau, sharp drop.
Loss of waveform. No CO2 detected. Indicates apnea, obstruction, displaced airway, equipment failure, or arrest.
Sloped or shark-fin waveform. Gradual rise rather than sharp rise. Indicates bronchospasm or partial airway obstruction.
Sudden drop. Sudden falloff of EtCO2 indicates loss of perfusion (cardiac arrest) or loss of airway connection (tube displacement, circuit disconnection).
Reading the waveform is the skill that distinguishes proficient capnography use from simple number-watching.
Equipment. Waveform capnography requires:
A capnography monitor (standalone or integrated into a multi-parameter monitor).
A sampling line (sidestream sampling) or in-line sensor (mainstream sampling) connected to the airway.
Power supply (battery for portable units, AC for fixed units).
Modern portable cardiac monitors used in EMS and tactical paramedic settings (Zoll X Series, LifePak 15, and similar) typically include integrated capnography capability.
COLORIMETRIC CO2 DETECTION
Colorimetric CO2 detectors are single-use chemical indicators that change color in the presence of CO2. They provide a yes-or-no answer to the question "is CO2 present at this point?" without requiring electronics, batteries, or training in waveform interpretation.
How they work. Colorimetric detectors contain a chemical (typically a pH-sensitive dye) that changes color when exposed to the acidic conditions produced by CO2. The detector is exposed to the gas being tested. If CO2 is present at sufficient concentration, the indicator changes color (typically from purple to yellow). If no CO2 is present, the indicator does not change.
Endotracheal tube confirmation. The original and most established colorimetric CO2 application. After endotracheal intubation, a colorimetric detector is placed between the endotracheal tube and the bag-valve-mask. Several breaths through the detector confirm CO2 presence (yellow color) for tracheal placement, or absence (purple) for esophageal placement. Common product examples include the EasyCap and StatCO2.
NEEDLE DECOMPRESSION INDICATOR KITS
Needle decompression indicator kits combine a needle decompression catheter with a colorimetric CO2 indicator, addressing a specific procedural confirmation problem.
The procedural problem. When performing needle decompression for suspected tension pneumothorax, the provider inserts a large-bore catheter through the chest wall into the pleural space. Confirming successful access to the pleural space has historically relied on:
Audible "rush of air" upon needle entry into a pressurized pleural space.
Tactile feeling of decreased resistance as the needle passes through the pleura.
Clinical improvement of the patient (relief of respiratory distress, hemodynamic improvement).
These confirmation methods have known limitations:
Background noise (ongoing tactical operation, helicopter, vehicle) can mask audible rush of air.
Tactile feedback is operator-dependent and can be unreliable in stressful conditions.
Clinical improvement may not occur if the indication was incorrect or if other factors are dominant.
In some cases, the needle does not actually enter the pleural space due to chest wall thickness, angle of insertion, or anatomic variation, but the operator perceives entry. The patient does not improve and additional intervention is required.
The colorimetric solution. A needle decompression indicator kit incorporates a colorimetric CO2 detector into the catheter assembly. When the needle successfully enters the pleural space and air begins to flow out through the catheter, the air contains some CO2 (from gas exchange with surrounding lung tissue, or from a hemopneumothorax containing carbonic compounds). The colorimetric indicator changes color, providing visual confirmation that air is actually flowing out of the chest cavity through the catheter.
The indicator confirms what the operator might otherwise have to infer. In tactical conditions where audible and tactile cues may be unreliable, the visual color change provides an additional verification that the procedure was successful.
Examples of commercial needle decompression indicator products include integrated catheter-and-indicator kits from various manufacturers. The category is relatively recent in tactical medical procurement and continues to evolve.
CAPNOSPOT
CapnoSpot is a brand of colorimetric CO2 detector designed for compact, low-cost confirmation applications. The device is a small adhesive or in-line indicator that changes color in the presence of CO2. CapnoSpot products are positioned for several use cases:
Endotracheal tube and supraglottic airway confirmation in field settings where waveform capnography is not available.
Verification of bag-valve-mask ventilation effectiveness.
IFAK-level inclusion as a low-cost confirmation tool.
Tactical scenarios where electronic capnography equipment is impractical.
The value proposition is simple, low-cost, electronics-free confirmation of CO2 presence at a specific point. CapnoSpot does not provide continuous monitoring, waveform analysis, or numerical readings. It answers a single yes-or-no question.
For procurement officers, CapnoSpot and similar colorimetric products fit into kit configurations where waveform capnography would be excessive (basic IFAKs, austere kits, training scenarios) but where some form of CO2 confirmation is desired.
WAVEFORM VS. COLORIMETRIC: WHEN TO USE EACH
Each capnography category fits different operational contexts:
Waveform capnography is appropriate for:
Tactical paramedic and SWAT medic aid bags.
Air medical and critical care transport.
ALS-level EMS units.
Hospital and trauma center settings.
Any scenario requiring continuous monitoring, waveform interpretation, or trend analysis.
Colorimetric detection (including needle decompression indicator kits and CapnoSpot) is appropriate for:
IFAKs and basic provider kits where waveform capnography is impractical.
Single-use confirmation applications (airway placement, needle decompression, ventilation effectiveness).
Austere and prolonged field care environments without reliable power.
Cost-sensitive deployments where waveform capnography is not justified.
Training and simulation scenarios.
Many tactical medical programs use both. Waveform capnography in the aid bag for sustained monitoring, plus colorimetric devices in IFAKs and as backups for specific procedural confirmations.
Provider scope. Capnography use is a provider-level skill at higher tiers:
Waveform capnography interpretation. Paramedic, tactical paramedic, and higher provider levels with specific training.
Colorimetric CO2 detection. Generally usable at lower training tiers with appropriate instruction. Single-use indicators are simpler to use than electronic monitors.
Procurement implications. Capnography capability across the kit hierarchy:
IFAKs. Colorimetric devices (CapnoSpot or equivalent) for cost-effective single-point confirmation.
Aid bags. Waveform capnography integrated with the cardiac monitor or as a dedicated capnograph. Spare colorimetric devices for backup confirmation.
Needle decompression. Indicator kits or stand-alone colorimetric devices to support procedural confirmation.
Training. Both waveform interpretation (provider levels) and colorimetric use (broader population). Skill maintenance through regular practice.
Documentation. Capnography findings (numerical values, waveform changes, color confirmation) documented in patient care reports.
Capnography in all its forms is one of the most useful assessment categories in modern field medicine. The shift over the past two decades from "no field capnography" to "capnography as standard for advanced airway management" has substantially improved the safety and reliability of tactical medical operations.
