gasp

gasp Life may begin with a gasp and end with a gasp, but the causes and results are quite different.

A gasp is a deep, near maximal inspiration through an open mouth, followed by breathing out which, unlike that of cough and sneeze, is not particularly forcible and is through an open larynx and mouth.

At birth the newborn emerges into a world suddenly filled with sensations, including possibly a slap on the bottom. The baby is blue and somewhat asphyxiated, the latter signalling to the brain to start the breathing process. The lungs, full of liquid, and collapsed by the squeezing confines of the birth canal, also send nerve signals to the brain to initiate the first gasping breath. As a result of these stimuli the first breath is exceptionally powerful, as it has to be, to overcome the strong resistance to airflow entering the liquid-filled lungs. Once air is in the lungs breathing becomes less forceful.

Gasping breaths continue to be taken throughout life, for much the same reasons as for the baby. In quiet breathing occasional deep breaths are always taken, usually every 5–20 min, as a kind of restrained gasp. These are called augmented breaths. The main cause is that in quiet breathing the lungs slowly and progressively deflate. Nerve endings in the lungs become sensitized to the deflation and, when their activity is great enough, their signals to the brain become strong enough to stimulate a deep, gasping breath. This large inflation of the lungs reverses the deflation and inhibits the sensory nerves, so the process is switched off until the lungs have slowly deflated again. The augmented breaths are not conspicuous when breathing is vigorous, as in exercise, and although colloquially we may talk of gasping from exertion this usually occurs after the effort. Augmented breaths are more frequent in some diseases where there is lung collapse or when the lung sensory nerves are activated, possibly in asthma, for example.

Other sensory inputs cause a gasp. Step under a cold shower or receive a painful stimulus, and an irrepressible gasp is almost inevitable. One can argue that this deep breath prepares the lungs and breathing for a rapid escape from the assault. The deep, gasping breath also reflexly stimulates heart rate, so the circulation is simultaneously brought to a state of readiness.

We gasp with emotion, as every romantic novelist knows too well. Again this may be a preparation for avoiding or other action, but it can also be a form of communication, so that observers see the strength of our reaction. We may ‘gasp out’ words in an urgent attempt at speech, but this is a physiological misuse of the term. Lie detectors rely in part on a deep, gasping breath when the subject is asked a question that activates his guilt.

In unconsciousness after a traumatic accident, the patient sometimes shows repetitive gasping instead of normal breathing, and this is an ominous sign, implying damage to the brain stem where breathing is controlled. The ‘last gasp’ in a dying patient is probably also an indication of brain stem malfunction, and is traditionally regarded as the last sign of impending death. But an ill or dying patient may have many ‘last’ gasps, and at death breathing usually fades quietly away.

John Widdicombe

See also breathing.