inspiration
(ĭn‵spĭr-ā'shŭn 
)
[L. in, in, + spirare, to breathe]
Inhalation; drawing air into the lungs; the opposite of expiration. The average rate is 12 to 18 respirations per minute in a normal adult at rest. Inspiration results in the spontaneously breathing person by the actions of the muscles of respiration (see below), or in the mechanically ventilated patient by ventilator pressure.
SEE: diaphragm for illus.; respiration .
Inspiration may be costal or abdominal, the latter being deeper. The muscles involved in forceful inspiration are the external intercostals, diaphragm, levatores costarum, pectoralis minor, scaleni, serratus posterior, superior sternocleidomastoid, and sometimes the platysma.
crowing i.The peculiar noise heard in stridor or croup.
SEE: croup, spasmodic.
forcible i.Inspiration in which the muscles of inspiration are assisted by accessory muscles of respiration, such as the sternocleidomastoids, intercostals, and serratus posterior. Forced inspiration is normal during vigorous exercise, but indicative of hypoxia, hypercarbia, or acidosis when it occurs at rest.
full i.Inspiration in which the lungs are filled as completely as possible (voluntarily, as in determining the vital capacity, or involuntarily, as in cardiac dyspnea).
mand atory i.Inspiration that is mechanically controlled, i.e., that either starts or stops because of a mechanical ventilator.
sustained maximal i.A deep-breathing maneuver that mimics the normal physiological sigh mechanism. The patient inspires from a resting expiratory level up to maximum inspiratory capacity, with a pause at end inspiration.