The following points highlight the two main methods of artificial respiration. The methods are:- 1. Manual Methods 2. Instrumental Respiration.
1. Manual Methods:
a. Schafer’s Method (Fig. 8.43):
The subject is laid in prone position and a small pillow is placed underneath the chest and epigastrium. The head is turned to one side. The operator kneels down by the side of the subject facing towards his head. Two hands are placed on the two sides of the lower part of the chest and then the operator slowly puts his body weight leaning forwards and pressing upon the loins of the subject. Intra-abdominal pressure rises, the diaphragm is pushed up and air is forced out of the lungs.
After this the operator releases the pressure and comes back to his original erect position. The abdominal pressure falls, diaphragm descends and air is drawn in. These movements are repeated about twelve times a minute (roughly the normal rate of respiration).
By this means it is possible to have a total pulmonary ventilation of 6,500 ml per minute, and this amount is sufficient for complete aeration of blood. The advantage of this method is that the patient being in the prone position, mucus or saliva comes out of the mouth and cannot obstruct his airways.
b. Sylvester’s Method:
The subject is placed in supine position. The operator stands or kneels at the head end and holds the two arms of the subject. The operator then raises the subject’s hands above his head and then folds the hands back upon the chest, compressing the chest wall at the same time.
Such movements alternately increase and decrease the thoracic cavity, thus drawing in and pushing out air from the lungs. This method is most commonly used in the operation theatre or in other accidents. The tongue should be kept pulled out and the mucus from the mouth cavity should be wiped out from time to time.
The rate is same as in Schafer’s method. In drowning cases, the water in the lungs must, at first, be driven out, by holding the subject upside down or revolving the subject by holding his legs. After this the subject should be given artificial ventilation. Respiratory level and volume during the artificial method has been presented in Fig. 8.46C.
c. Holger-Nielson Method (Fig. 8.44):
The subject is placed in the prone position with the arms abducted at the shoulders and elbows remaining flexed. The face is turned to one side and rests on the hands. The mouth is cleaned after wiping out mucus, fluid, etc., from it. The operator kneels down in front of the subject facing towards the head. Two hands are placed on the two sides of the back of the chest with the thumbs and fingers spread apart.
Then the operator puts his body weight leaning forwards upon the subject’s back. This compresses the chest and helps in expiration. The subject’s arms forwards by holding them above the elbows. This helps in natural inspiration. This process is repeated about 10-12 times a minute. The respiratory level and volume during this artificial method have been presented in Fig. 8.46B.
d. Mouth-to-Mouth Method (Fig. 8.45):
The subject is laid in the supine position with extended head. The operator sits by the side of the subject’s head. The operator hold the lower jaw of the subject by one thumb and index-finger and clamps the nostrils with the other thumb and index-finer. The operator then keeps his mouth over the subject’s mouth and exhales forcibly which causes inflation of the lungs and thorax. The operator then takes off his mouth and the process is repeated 10-20 times per minute. It is positive-pressure breathing. The respiratory level and volume during this artificial method have been presented in Fig. 8.46A.
e. EVE’s Rocking Method:
The patient is tied on a stretcher. The head and feet are alternately tilted through an angle of 45°. Eight or nine movements are carried out per minute, 7 seconds for each movement—4 seconds head down and 3 seconds feet down. When the head is down, the weight of the abdominal viscera presses against the diaphragm, so that air is pushed out of the lungs (expiration). When the feet are down, diaphragm descends and air is drawn into the lungs (inspiration). This method is useful aboard ship when a hammock can be used.
2. Instrumental Method:
Instead of a human operator, machineries are used. The advantage is that it can be carried on for good length of time, whereas the human operator is likely to be fatigued.
The machines generally work on two principles:
i. Negative-pressure breathing by alternately compressing and relaxing the chest wall and
ii. Positive-pressure breathing by introducing air or oxygen directly into the lungs-intermittently or continuously.
Some of the methods working on the first principle are mentioned below:
a. Drinker’s Method (Fig. 8.47):
In this method the patient is placed in an airtight chamber, the head remaining outside. By mechanically driven pumps, the pressure in the chamber is alternately lowered and raised. When the pressure is lowered the chest swells up and air is drawn into the lungs. When the pressure is raised chest becomes compressed and air is pushed out.
In this way, artificial ventilation may be continued for any length of time. These methods are very useful in cases where prolonged artificial respiration is necessary, such as in morphine poisoning, in paralysis of the respiratory muscles, as in poliomyelitis, pneumothorax etc. [The so-called iron lungs is an instrument working on this principle.]
b. Bragg Paul’s Method:
A rubber bag is wrapped round the chest wall of the subject. By suitable pumps, pressure in the bag is alternately raised and lowered thus compressing and relaxing the chest wall alternately. In this way respiration is carried out.
Some of the methods working on the second principle are as follows:
a. Continuous Insufflation Method:
This method is used in subjects who are to undergo operation requiring opening of the thorax. It is obvious that none of the above methods are applicable here. A thin flexible tube is inserted in the trachea as far as its bifurcation and a constant stream of oxygen (with or without 5% CO2) is allowed to pass into the lungs so that lungs remain slightly distended. In this way it is possible to maintain respiration without any movement of the subject.
b. Intermittent Inflation Method:
This method is adopted to maintain the respiration of animals during experiments. Various types of apparatus have been designed for this purpose. In the simplest method, a cannula is introduced and tied to the trachea. Warm moist air is driven into the lungs from a rhythmically acting pump. After each blast, the lung collapses and air is expelled through a side tube in the cannula. When artificial gas mixtures are used, a very elaborate apparatus is required.
c. Tank respirator (Fig. 8.48A):
In tank respirator the patient’s body is placed inside the tank and his head is protruded through a flexible but airtight collar. Opposite to the patient’s head there is a motor-driven leather diaphragm that moves back and forth with sufficient excursion to raise and lower the pressure within the tank.
Inward movement of leather diaphragm gets to produce positive pressure around the body and causes expiration; and outward movement of leather diaphragm produces negative pressure and causes inspiration. In this condition, positive pressure that causes expiration rises to 0 to + 5 cm water and the negative pressure that causes inspiration falls to — 10 to —20 cm water.
(d) Resuscitator (Fig. 8.48B):
This apparatus forces air through the mask that fits over the patient’s face into the lungs of the patient during the positive pressure cycle and then either allows air to flow out the lungs during the remainder of the cycle or pull the air out by negative pressure.Resuscitator commonly has safety valve which prevents the positive pressure from rising normally about +14 mm Hg the negative pressure from falling below – 9 mm Hg.
In the New-Born Baby:
Artificial respiration is necessary for those newly born babies, whose respiration is delayed.
The methods and principles followed in such cases are as follows:
i. Holding the baby upside down (to allow more blood to go to the brain) and patting on the back (reflex stimulation).
ii. Alternately putting the child in warm and cold water (reflex stimulation). In the maternity hospitals various other methods are employed working on these principles.
iii. Pumping CO2 through the nostrils or mouth into the lungs of the child. This is usually done by forcibly blowing through the mouth of the child after closing its nostrils. This is supposed to raise the CO2 tension of blood and stimulate respiratory centres. Mouth-to-mouth resuscitation is quite effective in infants.