How can you tell if the endotracheal tube is inserted at the correct position and depth? It’s easy to tell based on the mnemonic “look, listen, touch”. Tracheal intubation is a skill that physicians in the anesthesiology department, ICU, and emergency department must master, and internists usually go to the anesthesiology department to learn tracheal intubation during their rotations. Respiratory physicians (especially those with RICUs) should be proficient in this skill as well. One of the things we do immediately after we finish extubating a patient is to confirm the position of the extubation catheter. This includes whether it has entered the trachea (or esophagus); and how deep it has entered the trachea. Determining whether the catheter has entered the trachea (or esophagus):This is an urgent issue. If the catheter mistakenly enters the esophagus without being detected, the consequences can be imagined: acute gastric dilatation, or even gastric perforation or rupture, may occur, while hypoxemia is difficult to be corrected; if it enters the trachea too deeply, so deep that it penetrates into the left (or right) bronchus, resulting in unilateral ventilation; and if it enters too superficially, right near the vocal folds, it can easily be dislodged. To ensure that the tracheal tube is actually inserted into the airway and not accidentally into the esophagus, one of the most important lessons to learn is that we witness the tip of the catheter actually going in between the vocal cords, and as long as we keep our eyes fixed on the movement, we cannot be mistaken unless we hallucinate. However, a beginner may remove his or her eyes after exposing the entrance to the vocal folds, at which point the tracheal intubation catheter is not even close to the vocal folds, and accidental entry into the esophagus is a possibility. In addition, there are many other ways to determine that the endotracheal tube has entered the trachea. First, look:Observe the thoracic undulation and stomach during ventilation, if the thoracic undulation is not obvious after ventilation, and the abdomen is obviously bulging, and there is reflux of gastric contents in the trachea, then the catheter mistakenly enters the esophagus undoubtedly. If the ventilator is connected and the waveform of the flow rate of exhaled air can be seen and the waveform is good, it is in the trachea. If you can monitor the patient’s end-expiratory carbon dioxide, if inserted into the trachea, can be seen in the expiration of carbon dioxide square wave, it is generally believed that the end-expiratory carbon dioxide monitoring is the most accurate, and the expiratory waveform monitoring is simpler, and the accuracy is also very high. Listening:Listen to the breath sounds in the chest and abdomen during ventilation. If the breath sounds are strong in the chest and not obvious in the upper abdomen, the tracheal tube is considered to be located in the trachea. If the catheter is in the stomach, we may also hear loud sounds in the bilateral chest during ventilation, but there is still a difference between this and the breath sounds, so we should pay attention to identify them. It does not mean that we hear the sound in the bilateral lungs to conclude that the catheter is in the trachea, not also three, touch, listen: after intubation, squeeze the chest, if you hear the breath sounds in the mouth of the tracheal tube, the airflow is obvious more suggestive of the trachea. Note that this is only “more likely”, not absolute. When determining the position of the catheter, be sure to pay attention to the monitoring of vital signs, if the judgment is unclear or vital signs deteriorate, you should decisively pull out the catheter, buckle the mask, pinch the balloon, and wait for adequate oxygenation and then reintubation, if necessary, you can ask a master to help. Judge how deep into the trachea:The above is to judge whether the catheter is in the trachea after intubation, and at the same time we also need to judge how deep the catheter is inserted into the trachea, which is also very important. For details, see below: the distance between the incisors and the glottis is approximately 15-18 cm for adult males (14-16 cm for females), and the distance between the incisors and the rump is 25-32 cm (23-30 cm for females). How deep is the tracheal tube inserted? It is generally accepted that the tip of the tube should reach the middle of the trachea, i.e., 4-5 cm below the glottis, without being too shallow or too deep. The depth of insertion is generally considered to be 23-25 cm from the incisors in men and 20-22 cm in women, depending on the size of the patient. Pay attention to the symmetry of the breath sounds on both sides of the chest with a stethoscope. If it is not symmetrical, the insertion depth may be too deep, withdraw a little bit, and listen again. It is better to take a chest X-ray to further adjust the catheter position, but clinically, we usually do not intentionally emergency bedside chest X-ray to determine the position, unless there are other reasons to take a chest X-ray (such as pneumonia), then you can look at the catheter position in passing.