In emergency medicine, endotracheal intubation (ETI) is commonly performed for patients
who require airway management due to acute respiratory failure, inadequate oxygenation or
ventilation, or an inability to protect the airway resulting from altered consciousness.
When ETI is performed outside of a cardiac arrest scenario, a series of steps are
followed to optimize the procedure. These steps aim to prevent hypoxia, maintain
hemodynamic stability, reduce the risk of aspiration, and increase the success rate of
ETI. This methodical approach is known as Rapid Sequence Intubation (RSI). RSI involves
preparing the necessary and auxiliary equipment, administering premedication, ensuring
oxygenation, and applying anesthetic and neuromuscular blocking agents, followed by the
placement of the endotracheal tube (ETT). The procedure concludes with confirming the
ETT's placement and providing post-intubation care.
The primary goal of ETI is to position the ETT through the vocal cords into the trachea,
ensuring that both lungs are ventilated effectively. Incorrect or unrecognized
endobronchial intubation can result in hypoventilation and collapse of the non-ventilated
lung, while the over-ventilated lung may suffer barotrauma or pneumothorax. Unrecognized
esophageal intubation, on the other hand, can lead to failure in ventilation, resulting
in hypoxia and subsequent complications, including brain damage and other morbidities.
Therefore, ensuring the correct placement of the ETT is crucial to avoid serious adverse
outcomes.
Various methods have been described to confirm correct ETT placement, including direct
visualization during intubation, observation of chest wall movements, bilateral
auscultation of lung sounds, end-tidal carbon dioxide (EtCO2) monitoring, fiberoptic
bronchoscopy, and chest X-ray. Among these, capnography is considered the gold standard.
However, in specific clinical situations, EtCO2 monitoring may be unreliable. Patients in
cardiac arrest, patients with severe hypotension, pulmonary embolism, or poor pulmonary
reserve may present lower than expected EtCO2 values. Similarly, gastric insufflation,
using antacids, or consuming carbonated beverages may result in false-positive readings.
The American College of Emergency Physicians (ACEP) guidelines recommend the use of
additional confirmation methods after ETT placement. Ultrasound (US) has emerged as a
relatively new technique for confirming ETI. Its advantages include being non-invasive,
portable, rapid, and capable of providing real-time, accurate results. Additionally, the
US is unaffected by environmental noise, which can be challenging in noisy environments
such as the emergency department. It is also not influenced by changes in pulmonary blood
flow.
Several ultrasound techniques have been described to confirm ETT placement. The most
commonly used methods include direct visualization of the ETT during intubation (tracheal
ultrasound), detection of the "lung sliding" sign via lung ultrasound to indicate lung
aeration and bilateral identification of diaphragmatic movement. Tracheal ultrasound can
detect esophageal intubation before ventilation begins, preventing unnecessary gastric
insufflation and its associated complications. The lung sliding sign and bilateral
diaphragmatic movement techniques can help identify endobronchial intubation by
visualizing pleural and diaphragmatic movement, respectively, thereby complementing
tracheal ultrasound and reducing the risk of missed endobronchial intubation.
A comprehensive literature review revealed that no studies have directly compared these
three ultrasound methods. Therefore, this study aims to evaluate the effectiveness of
these three ultrasound techniques in confirming ETT placement and to compare the time
required for each method. A secondary objective is to compare the time spent using
ultrasound with that of auscultation and capnography. Additionally, this study will
assess the ability of each ultrasound technique to detect tracheal intubation and, if
present, accidental esophageal intubation across all patients.