Endotracheal Tube Placement Verification

Immediate Confirmation Strategies

• The American Heart Association recommends using both a clinical assessment (bilateral chest rise, equal breath sounds, absence of gastric insufflation sounds, and pulse‑oximetry) and end‑tidal CO₂ monitoring (capnography or colorimetry) immediately after intubation to confirm tracheal placement, because no single method is completely reliable. 1, 2

Primary Confirmation Method

• Continuous waveform capnography is the gold‑standard method for confirming and continuously monitoring correct endotracheal tube (ETT) placement (Class I recommendation). 3, 4
• In patients with a perfusing cardiac rhythm, capnography shows 100 % sensitivity and 100 % specificity for detecting correct tracheal placement. 4
• When waveform capnography is unavailable, colorimetric CO₂ detectors may be used as the initial confirmation method (Class IIa recommendation). 3, 4

Clinical Assessment Adjuncts

• Perform the following physical‑exam checks concurrently with CO₂ monitoring:
  
  • Observe bilateral chest rise during ventilation. 1, 2
  • Auscultate for equal breath sounds over both lung fields, especially the axillae. 1, 2
  • Listen over the stomach for gastric insufflation sounds; these should be absent if the tube is in the trachea. 1, 5
  • Verify pulse‑oximetry values when a perfusing rhythm is present (recognizing that SpO₂ may remain normal for up to 3 minutes after an esophageal intubation). 1, 2

Two‑Point Verification Standard

• The British Society of Anaesthesia endorses a two‑point verification that combines:
• This combination is essential because CO₂ detection alone cannot exclude right‑mainstem bronchus intubation. 1, 2, 5

Management When CO₂ Detection Fails or Is Uncertain

• During cardiac arrest, perform direct laryngoscopy to visualize tube position (Class IIa); absent CO₂ may reflect low pulmonary blood flow rather than misplacement. 1, 5, 7
• If capnography is unavailable, an esophageal detector device (EDD) may be used as an initial confirmation method in cardiac arrest (Class IIa). 3, 4
• When uncertainty persists, repeat direct laryngoscopy to confirm that the tube is positioned between the vocal cords. 1, 2

Limitations of the Esophageal Detector Device

• The EDD may give false‑negative or false‑positive results in patients who are morbidly obese, in late pregnancy, experiencing status asthmaticus, or have copious secretions that cause tracheal collapse. 8, 3

Situations Causing False‑Negative CO₂ Readings

• Low pulmonary blood flow (e.g., cardiac arrest). 3, 4
• Pulmonary embolism reducing CO₂ delivery to the lungs. 3, 4
• Severe airway obstruction such as status asthmaticus. 5, 7, 9
• Pulmonary edema. 5, 7, 9
• Contamination of the CO₂ detector with gastric contents or acidic drugs (e.g., endotracheal epinephrine), which may produce a constant color change in colorimetric devices. 5, 7, 9
• Intravenous epinephrine bolus, which can transiently lower pulmonary blood flow below detection thresholds. 5, 7, 9
• Large glottic air leak, diluting exhaled CO₂ concentration. 5, 7, 9

Radiographic Confirmation

• The American Heart Association advises obtaining a chest X‑ray in hospital settings to ensure the ETT is not in a mainstem bronchus and is positioned in the mid‑trachea. 1, 2, 5

Ongoing Monitoring Protocol

• Verify ETT placement at multiple time points (Class I recommendation):
  
  • Immediately after intubation. 1, 2
  • After the tube is secured. 1, 2
  • During patient transport. 1, 2
  • Whenever the patient is moved (e.g., from gurney to bed). 1, 2
• Maintain continuous waveform capnography throughout care to detect tube displacement promptly. 3

Post‑Intubation Deterioration Assessment

• If the patient deteriorates after intubation, the American Heart Association recommends the DOPE mnemonic to systematically evaluate the cause:
  
  • Displacement of the tube. 1, 2
  • Obstruction of the tube. 1, 2
  • Pneumothorax. 1, 2
  • Equipment failure. 1, 2

All facts are drawn from cited references and reflect the strength of recommendation where specified.

Guideline for Confirmation and Monitoring of Endotracheal Intubation

1. Preferred Confirmation Methods

• Continuous waveform capnography is the most reliable method for confirming and monitoring endotracheal tube placement; it provides 100 % specificity for correct tracheal positioning and allows ongoing verification after insertion. Class I recommendation of the American Heart Association. 10
• Upper‑airway ultrasound offers a significantly faster confirmation (≈ 5–16 s vs 15–24 s for capnography) and its accuracy does not depend on pulmonary blood flow, making it superior in cardiac arrest or low‑output states. 11

2. Diagnostic Accuracy

3. Advantages of Each Modality

3.1 Capnography

• Enables continuous post‑intubation monitoring of tube position and ventilation‑perfusion status. 12
• Does not require an experienced operator once the sensor is installed. 13
• Provides additional information on ventilation quality and perfusion. 10

3.2 Ultrasound

• Independent of pulmonary blood flow; effective in cardiac arrest, pulmonary embolism, and severe hypotension. 11
• Unaffected by severe airway obstruction, pulmonary edema, or gastric content contamination. 11

4. Limitations

4.1 Capnography

• False‑negative CO₂ readings can occur with low pulmonary blood flow (cardiac arrest), pulmonary embolism, severe airway obstruction, pulmonary edema, detector contamination, or transient reduction of flow after IV epinephrine. 13
• False‑positive CO₂ may result from recent ingestion of carbonated liquids. 13
• Colorimetric or non‑waveform detectors are not accurate for continuous monitoring. 14
• Requires a minimum CO₂ threshold, limiting reliability in cardiac arrest. 11

4.2 Ultrasound

• Operator‑dependent; requires specific training and experience. 15
• Abnormal airway anatomy may hinder image interpretation. 15
• Equipment availability may be limited in some settings. 15

5. Clinical Algorithm

5.1 Patients with Adequate Perfusion (not in cardiac arrest)

• Primary confirmation: Continuous waveform capnography (Class I). 10
• Adjunct: Ultrasound can be used simultaneously for faster confirmation if an experienced operator is present. 15

5.2 Patients in Cardiac Arrest

• Primary confirmation: Upper‑airway ultrasound if an experienced operator is available. 11
• Secondary check: Capnography may yield false‑negative results due to low pulmonary flow; interpret cautiously. 15
• If no CO₂ is detected: Perform direct laryngoscopy to visualize tube placement. 10

5.3 Uncertainty with Any Method

• Employ the alternative technique as a secondary confirmation. 11
• Conduct direct laryngoscopy to directly view the tube passing the vocal cords. 16

5.4 Continuous Post‑Intubation Monitoring (All Patients)

• Always use continuous waveform capnography (Class I) for ongoing verification of tube position. 12

6. Practical Recommendations

• Avoid reliance on auscultation and chest rise alone; these clinical signs have low specificity.
• Do not assume esophageal intubation solely because CO₂ is absent in cardiac arrest; use a secondary method (ultrasound or direct laryngoscopy). 10
• Do not use colorimetric detectors for continuous monitoring; reserve them for initial confirmation only. 14
• Ensure adequate ultrasound training before employing it as a primary confirmation tool. 15
• Apply two‑point verification (direct visualization + sustained CO₂ or ultrasound) whenever feasible. 17