Respiratory system additional information

Carina: The carina is the point where the trachea divides into the right and left main bronchi. It’s usually midline, with the spinous process directly behind it. Healthcare providers also use the carina to confirm correct endotracheal tube (ET) placement after intubation. Typically, the tip of the ET tube should be 3-4 cm above the carina so both lungs are ventilated.
Clavicle: The head of the clavicle attaches to the lateral surface of the sternum. On a chest radiograph, the position of the clavicular heads relative to the trachea helps you judge whether the patient was properly positioned (and not rotated) when the image was taken. The two clavicular heads should appear on either side of the trachea, with the spinous processes centered between them.
Hemidiaphragms: The right hemidiaphragm normally sits slightly higher than the left because the liver beneath it limits how far it can descend during inspiration. Important clinical pearls include:
1. Each dome of the diaphragm has its own nerve supply from the phrenic nerve. Because of this, damage to the nerve on one side won’t affect the other side. On a chest radiograph, a paralyzed hemidiaphragm appears higher than the other during inspiration, creating a paradoxical pattern of movement with respiration.
2. You should not see free air under a hemidiaphragm. If free air is present, you may see a black line under the hemidiaphragm, which is concerning for bowel perforation. This requires emergent evaluation with a CT scan and a surgical consult. Don’t confuse the normal gastric bubble (commonly seen on chest radiographs) with free air.
Trachea: The trachea should be midline and positioned between the right and left clavicular heads. If it deviates from midline, consider patient rotation during the radiograph, a mediastinal mass, or a tension pneumothorax.
Box for Clara cells: Clara cells (also called club cells) are non-ciliated, cuboidal secretory cells. They have prominent Golgi apparatus, endoplasmic reticulum, and cytochrome P-450. They secrete club cell protein (CC16), also known as uteroglobin or secretoglobin, which is stimulated by gamma interferon and TNF-α. Clara cells are one of the primary sources of stem cells in the respiratory epithelium. They have an immunomodulatory role and also protect surfactant. Deficiency of CC16 is associated with an increased risk of viral infections and oxidative stress in the lungs. In addition to the lungs, they are also present in the prostate, kidneys, and gravid uterus.

Carina: The carina is the point where the trachea divides into the right and left main bronchi. It’s usually midline, with the spinous process directly behind it. Healthcare providers also use the carina to confirm correct endotracheal tube (ET) placement after intubation. Typically, the tip of the ET tube should be 3-4 cm above the carina so both lungs are ventilated.
Clavicle: The head of the clavicle attaches to the lateral surface of the sternum. On a chest radiograph, the position of the clavicular heads relative to the trachea helps you judge whether the patient was properly positioned (and not rotated) when the image was taken. The two clavicular heads should appear on either side of the trachea, with the spinous processes centered between them.
Hemidiaphragms: The right hemidiaphragm normally sits slightly higher than the left because the liver beneath it limits how far it can descend during inspiration. Important clinical pearls include:
1. Each dome of the diaphragm has its own nerve supply from the phrenic nerve. Because of this, damage to the nerve on one side won’t affect the other side. On a chest radiograph, a paralyzed hemidiaphragm appears higher than the other during inspiration, creating a paradoxical pattern of movement with respiration.
2. You should not see free air under a hemidiaphragm. If free air is present, you may see a black line under the hemidiaphragm, which is concerning for bowel perforation. This requires emergent evaluation with a CT scan and a surgical consult. Don’t confuse the normal gastric bubble (commonly seen on chest radiographs) with free air.
Trachea: The trachea should be midline and positioned between the right and left clavicular heads. If it deviates from midline, consider patient rotation during the radiograph, a mediastinal mass, or a tension pneumothorax.
Box for Clara cells: Clara cells (also called club cells) are non-ciliated, cuboidal secretory cells. They have prominent Golgi apparatus, endoplasmic reticulum, and cytochrome P-450. They secrete club cell protein (CC16), also known as uteroglobin or secretoglobin, which is stimulated by gamma interferon and TNF-α. Clara cells are one of the primary sources of stem cells in the respiratory epithelium. They have an immunomodulatory role and also protect surfactant. Deficiency of CC16 is associated with an increased risk of viral infections and oxidative stress in the lungs. In addition to the lungs, they are also present in the prostate, kidneys, and gravid uterus.