An advanced airway, such as an Endotracheal Tube (ETT) or a Laryngeal Mask Airway (LMA), is placed to secure a patient’s breathing and ensure oxygen delivery. These devices bypass the upper airway and connect directly to the breathing system, often used in emergencies when a patient cannot protect their own airway. Immediate and accurate verification of placement is necessary because placing the tube in the esophagus (food pipe) instead of the trachea (windpipe) prevents oxygen from reaching the lungs and can result in severe harm or death.
Initial Physical Assessment Checks
The initial steps for confirming advanced airway placement rely on the provider’s senses and are performed immediately after tube insertion. The first check involves auscultation, or listening with a stethoscope, over the epigastrium (the upper part of the stomach). Hearing gurgling sounds over the stomach indicates that the tube has been mistakenly placed in the esophagus, causing air to inflate the stomach.
The provider then listens over both sides of the chest (apices and bases) to ensure breath sounds are present and equal bilaterally. If breath sounds are louder on one side, it suggests the tube has been advanced too far into one of the main bronchi, a complication known as mainstem intubation. Visual confirmation involves watching the patient’s chest for equal and symmetrical rise and fall with each assisted breath.
Other immediate physical signs include observing for condensation inside the advanced airway tube during exhalation, indicating warm, moist air movement. The ease with which the provider can ventilate the patient using the bag-valve mask is also assessed, as increased resistance may suggest a problem with lung compliance or airway obstruction. These sensory checks are quick and foundational, but they are subjective and not considered definitive proof of correct tracheal placement alone.
Quantitative Waveform Capnography
Quantitative waveform capnography is the most reliable method for confirming correct advanced airway placement and is considered the standard of care. This device provides continuous, non-invasive measurement of the concentration of carbon dioxide (CO2) in the patient’s exhaled breath, known as End-Tidal CO2 (ETCO2). The mechanism relies on CO2 being a waste product of cellular metabolism carried by the blood to the lungs for exhalation.
A consistent, measurable level of ETCO2 confirms that the tube is correctly positioned within the airway leading to the lungs, allowing CO2 to be expelled and detected. A normal reading falls within the range of 35 to 45 mmHg in a patient with adequate circulation. Conversely, if the advanced airway is placed in the esophagus, the device will register a flat line or a zero reading because the stomach does not produce this gas.
Beyond a simple numerical value, the device produces a capnogram, which is a real-time, breath-to-breath graphical display of the CO2 levels. This waveform is a squared-off shape, with distinct phases corresponding to inhalation and exhalation, providing objective evidence of consistent air movement. A sustained and regular waveform confirms tracheal placement, while an irregular, low-level, or absent waveform suggests misplacement or poor blood circulation. Continuous capnography also monitors the tube’s position over time and provides feedback on the quality of chest compressions during cardiopulmonary resuscitation.
Adjunctive Confirmation Tools
While capnography is the primary method, other tools supplement or confirm placement, particularly when capnography readings may be compromised, such as during cardiac arrest with low blood flow. One simple device is the colorimetric CO2 detector, which uses a chemical reaction to change color (often from purple to yellow) when exposed to CO2. These detectors are less sensitive than waveform capnography and may not register a color change immediately, especially in states of low perfusion.
Another technique involves the Esophageal Detector Device (EDD), a syringe or self-inflating bulb that creates negative pressure at the end of the advanced airway. When the device is attached, if the tube is in the rigid trachea, the device will expand easily, indicating free air movement. If the tube is in the soft, collapsed esophagus, the walls of the esophagus will stick to the tube tip, preventing the device from expanding.
For complex situations or difficult anatomy, advanced visualization techniques can be employed. This includes using a fiber optic scope, or bronchoscope, which allows the provider to directly see the tube passing through the vocal cords into the trachea. The use of a Gum Elastic Bougie (GEB) can provide tactile feedback, where the tip is felt bouncing or clicking over the tracheal rings, offering another layer of objective confirmation. These methods are considered secondary and do not replace the mandatory use of continuous waveform capnography.
Protocol When Verification Fails
If any verification method, especially the absence of a sustained capnography waveform, suggests the advanced airway is misplaced, immediate action is necessary to prevent oxygen deprivation. The provider must presume the tube is in the esophagus and immediately remove the device.
Following tube removal, the patient must be immediately re-oxygenated using a Bag-Valve-Mask (BVM) and supplemental oxygen. Troubleshooting should not take more than a few seconds, typically under one minute, before proceeding to removal and re-oxygenation. Once the patient is stabilized with basic airway support, the provider must prepare for a second attempt at advanced airway placement or switch to an alternative airway management strategy.