Diaphragm
The dome-shaped sheet of muscle that separates the chest from the belly and does most of the work of quiet breathing.
Why the exam cares
A weak or crowded diaphragm shows up as shortness of breath that gets worse lying flat and fast, shallow breathing; the belly sinking in as the chest rises is a later, more serious sign. The nurse answers it by sitting the patient up, helping the cough, and protecting the airway when breathing fails.
How to find it
- Its edges attach to the xiphoid, the lower six ribs, and the upper lumbar spine, but the domes rise high inside the rib cage: about the 5th rib on the right and the 5th intercostal space on the left at the end of a quiet exhale. The right dome sits higher because the liver lies under it.
- To find its level, have the patient breathe out fully and hold while you percuss down the back until resonant lung turns dull, and mark that spot; then have the patient breathe in fully and hold, and percuss and mark again. The distance between the marks is diaphragmatic excursion, normally about 3 to 5 cm and equal on both sides.
- Watch the belly on inhale, best with the patient lying flat. A working diaphragm pushes the abdomen out; a paralyzed or failing one lets the belly sink in as the chest rises.
Procedure
Assisted cough after neck injury
The phrenic nerve leaves the cord at C3 to C5 (see Spinal cord for what the level means). With a lower cervical injury the diaphragm still works but the intercostal and abdominal muscles do not, so the cough cannot clear secretions; the nurse gives an assisted (quad) cough, hands flat on the upper abdomen below the xiphoid, pushing up and in as the patient coughs, and avoids doing it right after a meal. In the first days, cord swelling can climb above the injury, so the nurse watches for the belly sinking on inhale and a weakening cough and reports it at once.
Procedure
Breathing retraining in COPD
The nurse teaches pursed-lip breathing: in through the nose, then out slowly through pursed lips with the exhale longer than the inhale, which keeps small airways open so trapped air can leave. Diaphragmatic breathing, one hand on the belly that rises on inhale, shifts the work back to the diaphragm and away from the neck and shoulder muscles.
Procedure
Positioning and hiatal hernia
Ascites and abdominal distension push the diaphragm up and shrink the room the lungs have to expand, so the nurse raises the patient to semi-Fowler's or high-Fowler's to let the dome drop. In a hiatal hernia, part of the stomach slides up through the diaphragm's opening for the esophagus; the nurse teaches small frequent meals, not lying down after eating, and sleeping with the head of the bed raised.
Emergency
Congenital diaphragmatic hernia
A newborn with a hole in the diaphragm, most often on the left, has bowel in the chest: a sunken (scaphoid) abdomen, bowel sounds heard over the chest, and respiratory distress, usually within minutes to hours of birth. The nurse avoids bag-mask ventilation, because it pushes air into the bowel in the chest and compresses the lungs further; the baby needs an endotracheal tube and a gastric tube to decompress the gut.