ARTIFICIAL RESPIRATIONAND

PULMONARY FUNCTIONTESTS

ARTIFICIAL RESPIRATION

Artificial respiration (rescucitation) is requiredwhenever there is an arrest of breathing, withoutcardiac failure. Arrest of breathing occurs in the following conditions:1. Accidents2. Drowning3. Gas poisoning4. Electric shock5. Anesthesia Purpose of artificial respiration is to ventilate thealveoli and to stimulate the respiratory centers.

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MOUTH TO MOUTH RESCUCITATION(MANUAL METHOD

Is an emergency measure performed when someonestops breathing. The patient is placed flat on the back.While pinching the patient’s nostrils shut, the aid-giverplaces his or her mouth on the patient’s mouth andblows forcefully into the patient’s lungs. This raises the alveolar pressure in the patient’s lungsrelative to the atmospheric pressure outside the chestand causes the lungs and chest to expand (inspiration). The rescuer then removes his or her mouth to allow thepatient to exhale. Expulsion of the air blown into thelungs (expiration) occurs due to the intrinsic elasticrecoil of the lungs and chest. This process can beaccelerated by pressing down on the chest.

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The rescuer should ventilate the patient at a rate ofabout 16 min–1. The expiratory O2 fraction of therescuer is high enough to adequately oxygenate thepatient’s blood. The color change in the patient’s skin from blue(cyanosis) to pink indicates that a resuscitationattempt was successful.

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MECHANICAL METHODS

This technique is used when the respiratory muscles areparalyzed due to disease, anesthesia, or when artificialrespiration is needed for long time.

TYPES OF MECHANICAL METHODS

DRINKER METHOD: The machine used in this method iscalled iron lung chamber or tank respirator. VENTILATION METHOD: Apparatus used for ventilation iscalled ventilator. Ventilator could either be volume or pressure ventilator

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PULMONARY FUNCTION TEST

Pulmonary function may be assessed clinically bymeans of a technique known as spirometry. In this procedure, a subject breathes in a closedsystem in which air is trapped within a light plastic bellfloating in water. The bell moves up when the subject exhales and downwhen the subject inhales The movements of the bell cause correspondingmovements of a pen, which traces a record of thebreathing called a spirogram

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Fig 1: A Spirogram showing lung volumes and capacities7

A lung capacity is the sum of two or more lungvolumes. For example, the vital capacity is the sum of the tidalvolume, the inspiratory reserve volume, and theexpiratory reserve volume. Note that residual volume cannot be measured with aspirometer because it is air that cannot be exhaled. Therefore, the total lung capacity (the sum of the vitalcapacity and the residual volume) also cannot bemeasured with a spirometer.

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TERMS DEFINITION

Tidal volume(about 500ml) The volume of gas inspired or expiredin an unforced respiratory cycle

Inspiratory reserve volume(about3000ml)

The maximum volume of gas that canbe inspired during forced breathing inaddition to tidal volume

Expiratory reserve volume(about1100ml)

The maximum volume of gas that canbe exspired during forced breathing inaddition to tidal volume

Residual volume(about 1200ml) The volume of gas remaining in thelungs after a maximum expiration

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TERMS DEFINITION

Total lung capacity(5800ml)VC+RV

The total amount of gas in the lungsafter a maximum inspiration

Vital capacity(4600ml)IRV+TV+ERV

The maximum amount of gas thatcan be expired after a maximuminspiration

Inspiratory capacity(3500ml)TV+IRV

The maximum amount of gas thatcan be inspired after a normal tidalexpiration

Functional residual capacity(2300ml)ERV+RV

The amount of gas remaining in thelungs after a normal tidal expiration

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…..OLURANTI O.I