ABSTRACT
Inspect the movement of the chest during quiet breathing, as this will reflect the patient’s degree of difficulty. In healthy subjects, the mouth is closed or slightly opened for nasal breathing. Normal respiration is evident with careful observation of the naked subject, as gentle thoracic cage and abdominal movements can be seen. With normal quiet breathing, the primary muscles of inspiration (the diaphragm and the intercostal muscles) are used predominantly. The accessory muscles of respiration (strap muscles of the neck, shoulder girdle, rectus abdominis) are not utilized or only tense slightly to fix the position of the thoracic cage. The thorax is stationary or moves outward slightly with inspiration, while the abdomen expands as the diaphragm descends. The thoracic and abdominal movements are synchronous and coordinated. The shoulders and neck are quiet and do not appear to participate significantly in breathing. Expiration is passive and hardly apparent. Expiration requires a slightly longer time than inspiration, and there may be substantial pauses be tween breaths. Normal people breathe at rest 8-15 times each minute. The respiratory rate at rest without speaking should be recorded.
