NEONATOLOGY ON THE WEB

Premature and Congenitally Diseased Infants

Chapter IX
Incubators

The History of Incubators -- The first records of the use of incubators are found in description of their employment for the hatching of eggs of fowls in Alexandria, and it is possible that it may have occurred to the Egyptians to apply this method to the new born. One cannot, however, assume this, for no author of that period has mentioned it. Hippocrates, in his writings of 460 B.C., makes the following statement: "No fetus coming into the world before the seventh month of pregnancy can be saved." We note that the literature of our day records only a limited number of exceptions to these conclusions that infants before the end of the twenty-eighth week are viable.

Pasquad quotes a thesis of the Eleventh Century of the Republic wherein the author, Rudellet, writing on the vitality of infants, reports the following which we think well worth citing. He quotes from Baillet (Decisions of Savants, Paris, 1722) as follows: "Among the records of celebrated children Baillet reports that of Fortunio Liceri, whose mother gave birth to him long before the ordinary time during the fatigues and shocks of a sea voyage. This fetus was no larger than the palm of your hand, but his father who was a physician, having examined it, had carried it to the place which was to be the end of his voyage. There he had other physicians see it. They found that there was lacking nothing essential to life, and his father undertook to finish Nature's task and to work at the formation of the child with the same skill that men exhibited in hatching chickens in Egypt. He instructed a nurse in all that she had to do in the maintaining of exactly measured artificial heat and the requirements for his general care and feeding. He lived to be seventy-nine years of age and distinguished himself in science by a large number of works."

This is a tale the recording of which leads us to believe that use was made of the knowledge of the methods used at that age in incubating fowls. We will dispense with any remarks and will content ourselves with mentioning the fact, in citing the reflection of the historian himself: "One must admit," says the author in concluding the narrative of which we have just given the analysis, "that all which is unbelievable is not always false, and that probability is not always on the side of truth."

Little is recorded from 1722 to 1857, the time when Denucé described his incubator. Modern French writers attribute the origin of the first incubator to Denucé, of Bordeaux, who in 1857 described his model which consisted of a double-walled tub which was to be filled with warm water at intervals (Fig. 130).

Clementovsky states that a somewhat similar contrivance was used by Rühl in St. Petersburg as early as 1835.

Credé, in 1866, published the results which he obtained with a similar apparatus which had been in use in his clinic in Leipzig since 1860, with the use of which he was able to lower his mortality by 18 per cent. This simple tub has bee modified by some of the continental clinicians by putting it on a stand and providing it with a hose attachment for connection with a hot-water faucet (Fig. 131).

In 1879 Winckel described a permanent bath in which the infant floated. This apparatus was an attempt at imitating intra-uterine conditions, but needless to say, because of the danger of drowning and infection, it proved unpopular. The water in this tub was kept between 36° and 38° C.

In 1860 Tarnier had an infant incubator constructed similar to those used as chicken incubators. This incubator was built for him by Odile Martin, director of the Paris Zoo, and was built of such size that it could hold several children; and was installed in the Maternity Hospital of Paris in 1881 (Fig. 132).

This is the first closed incubator which may be qualified as modern, for the perfected apparatus of our day differs from it only in detail.

This is the time that dates the principal work undertaken on incubator construction, and the most varied modifications have followed each other almost without interrupt until our day.

The most important work on the results obtained by their use is an account by Auvard in 1883. In this interesting work the author gives the first statistics on the use of the incubator in the Maternity in this period under the scientific direction of Tarnier.

Berthod, an interne of Tarnier, in an excellent thesis (1887), continued this study, adding thereto some new data on the conditions indicating the use of an incubator for the new-born infant. His statistics are still most imposing, and they treat upon almost a thousand cases in which the incubator was used. Among the most influential of these was Budin.

The monographs of Auvard and Berthod are the only two important early works treating of the study of incubators and the results of their use. Their work shows the importance of the prevention of hypothermia, and they lay particular stress upon the protection of the infant from the moment of its birth. It may be stated with justice that the early progress in the care of premature infants was to a great extent influenced by the interest of the French obstetricians in the care of these infants.

Since then a large number of authors have written on this subject, but it is rather to modify certain details or to propose new forms of apparatus than to give new rules.

From that time on until our day the incubator has undergone changes -- some quite radical, while some have remained as rudimentary as when first originated.

Only those models demonstrating more important changes and improvements will be described.

Hearson introduced automatic temperature regulation within the incubator. His apparatus was so constructed as to set off an electric alarm clock when the maximum temperature desired was past. This apparatus was modified by Eustache who attempted to attach automatic gas or oil-heating apparatus to the so-called "thermostat nurse of Hearson."

In 1896 Diffre, of Montpelier, and Lion built metal incubators, providing for what they termed final perfection which provided for automatic heating through thermostat control, the heat being furnished through a hot-water system heated by an oil or gas stove at the side of the incubator. In this incubator refinements in ventilation and control of humidity were introduced.

A giant incubator was prepared by Prof. Pajot, in 1885, for use in his clinic, consisting of a large heated chamber, practically an oven; the congenitally feeble infants, entirely separated from their mothers, being fed and tended by wet-nurses.

Budin, in stating the disadvantages of the Pajot apparatus, said: "The wet-nurses were obliged to feed and tend the infants in this oven; and the mothers, separated from their infants, soon lost all interest in those whom they were unable to nurse and cherish. It is better by far to put the little one in an incubator by its mother's side."

Prof. Hutinel, of Paris, whose studies on the subject are of interest, constructed a couveuse composed of a boat-like vessel of enameled crockery whose bottom was replaced by a plate of galvanized sheet-iron pierced by holes. The plate served as a cover to a metal box, which contained three bowls filled with hot water. The top of the apparatus was closed by a heavy glass which could be raised to a desired degree by the aid of a screw, and which allowed the airing of the box. The water bowls were replenished every two or three hours to maintain the temperature. The crockery tub could be disinfected with ease by wiping it with a cloth saturated with bichloride of mercury solution, which was its best feature.

Simple and cheap in its operation is Finkelstein's incubator. The essentials of its construction may be seen from the accompanying illustration (Fig. 133). The circular holes in the side walls of the box for inserting hot-water vessels also serve as inlets for the incoming air, while the used air escapes through the holes at the upper part near the cover.

Rommel's apparatus proved to be good and is at the same time like the latter easily carried from one place to another (Fig. 135). The chamber is 0.83 cubic meter large, enclosed on three sides by mirror glass, the corner being rounded to facilitate cleaning. The ventilating shaft permits the air to be renewed 100 to 120 times every hour. The humidity regulation is simple. The large supply of hot water of about 15 to 20 liters permits a pretty constant temperature, the fluctuations according to Rommel being less than 1°. For heating electric incandescent lamps are used.

Moll's incubator (Fig. 138) distinguishes itself by the fact that the head of the infant remains outside the warm box and breathes the air of the room, this having a great advantage for respiration of debilitated infants, since, because of stronger respiratory stimulus, attacks of asphyxia may be more easily avoided.

To this class of incubators, which are all modifications of the original Lion type, belong the models of Couney, DeLee and others now on the market in the United States (Fig. 136 and 137).

These models differ but slightly in principle, the chief variation being in the manner of heating and distributing the air and supplying moisture. They may be heated by gas or oil stoves situated at the side of the incubator, heating air as it enters, or by a system of electric bulbs within the incubator. In the latter models the bulbs are usually located either in the floor or sides. The best models are those in which the heating system is modelled after that used in hot-water heating plants for houses. The temperature is automatically controlled by a thermostat.

A thermometer is fastened near the side window, so that it may be easily read, and a hygrometer is used to indicate the degree of moisture.

This type of incubator has in the past ten years lost considerable of its early popularity, as is evidenced by a visit to most of the large hospitals. A great deal of this deserved unpopularity is due to the inability to ventilate them in the ward and the necessity for furnishing a trained assistant. To properly supply these incubators with a free current of air it is necessary to connect them so that they will receive a supply of air from outside of the building. To counteract the tendency to an insufficient air current in the absence of windows or when they are in the wrong direction an electric fan should be incased on the outside of the building in such position that air may be blown directly through the incubator. This is difficult of arrangement when the incubators are located above the first floor of the building. When the station is located on the first floor it is necessary to avoid the dampness and dust of the street level, and this can be accomplished by installing a large funnel 15 or 20 feet above the ground level, some 24 to 36 inches in diameter, to which is attached a 10-inch stack which can be connected with a cage at its base in which the electric fan is installed. From this point the air is blown through the system of incubators.

When such a considerable quantity of air is blown into the incubator system, it becomes necessary to filter it through several layers of cotton. This is best done at the side of the individual incubator.

The Cincinnati Hospital uses an electrically heated bassinette. The temperature is regulated by a series of electric lamps under the mattress. The appartus consists of a double wall frame, with hot air rising in this double wall and escaping through small holes near the top which can be opened or closed as required by a slide damper.

In 1914 the writer designed an electric heated water-jacketed infant bed.

It combines the double-wall water jacket with insulation to prevent external loss of heat, and electric heating by a large plate with rheostat control.

For hospital and home equipment the bed answers many requirements, because of its simplicity of operation in any well-ventilated and moderately heated room.

It can be used for the care of premature infants, for the protection of the new-born full-term infant immediately after delivery and for infants suffering from hypothermia from other cauess.

This bed fulfils the following needs of the infant: (1) Safety. The maximum temperature which can be obtained within the bed is about 110° F. when the lid and canopy are in place with a room temperature of 70° F. While such a temperature would be injurious if maintained for a long period of time, such surroundings if temporary can cause but little injury. (2) Simplicity of operation. It requires practically no attention unless there are extreme ranges of temperature within the ward, since the asbestos insulation prevents radiation from the outer surface of the bed and the heater holds the water at a constant temperature. (3) Ventilation. This apparatus assures the baby of an adequate supply of fresh air if placed in an ordinary room which is well ventilated. (4) Humidity is maintained at nearly the same degree as the surrounding air because of the almost constant change of air within the bed and moisture supplied by an evaporation pan beneath the crib. (5) It is easily cleaned and disinfected.

The construction of the bed is such that it can be used in an ordinary ward or room, giving the infant the advantage of a most perfect room ventilation.

The following suggestions will aid in the practical application of this bed for use in hospitals or the home.

A special room should be provided. This has a practical advantage as it impresses the nurses to consider this room as barriered. This will make a demand upon the nursing staff for observation of all of the rules of aseptic nursing.

This room should be supplied with an ample system of heating coils controlled by a thermostat for winter use, thereby facilitating the maintenance of a more or less stable temperature in the room which should, in so far as possible, range between 68 and 75° F.

The temperature within the room and bed should be read and charted at six-hour intervals, best at 6 A.M., 12 M., and 6 and 12 P.M. as the most likely time for maximum changes in the ward temperature.

Ventilation should be adequate but not excessive, and the room should be so constructed that the beds may be placed without the line of direct air currents. This is accomplished by having the ventilating windows and transoms on one side of the room, while the opposite side is built with non-ventilating windows or blank walls at either end.

Humidity in so far as the room is concerned will require little attention except at such time when considerable artificial heating is necessary. To supply the needed moisture during cold water when ventilation of the room is more or less limited, a large evaporating pan should be in direct contact with the radiator coils. When these means fail to furnish the desired moisture, a wet sheet may be hung in the room and remoistened as indicated by the hygrometer.

In so far as possible the relative humidity should be kept at about 55 per cent. However, amounts less than this down to 45 per cent will usually cause little or no discomfort or retardation of progress. It has been our experience that with a good free ventilation through open transoms or windows when the temperature of the room does not exceed 80° F., the normal water content of the air is quite sufficient and little or no attempt at influencing the room humidity is necessary. However, this will not answer the purpose where a closed room is used.

When a special room cannot be provided the beds for well prematures should be kept in the nursery used for normal infants. They must never be brought into contact with infected infants because of the danger of crossed and mixed infections. Neither should infected prematures be placed among well new-born infants.

All infants should be removed from this room to the nursery once daily, so that it may be thoroughly ventilated and cleaned by the use of soap and water. Before replacing the infants the air should be reheated to remove excessive humidity.

Care of the Bed

General Care. -- Once daily the infant should be removed from the bed to allow of cleaning the interior with a damp cloth. This is best done at the time of renovating the room. The crib itself should also be wiped with a damp cloth. All linens should be changed at once daily and at other times when soiled. Extra mattresses should be supplied so that they may be given an airing on alternate days and a thorough renovating as frequently as soiled. Renovation is imperative between cases. Mattresses should be protected by rubber sheeting. A thick pad, however, must be placed between the rubber sheeting and the infant.

The heating apparatus consists of a plate with a 6-inch surface in direct contact with the floor of the water jacket, and especially constructed to carry a maximum capacity of 300 Watts, which makes it impossible to heat the water above 155° F. and the interior of the bed above 110° F. at a room temperature of 70° F.

A rheostat with seven contacts is fastened to the standard. Six of them are graduated to take current varying from 25 Watts on contact 1 to 300 Watts on contact 6. The first contact shuts off the current.

For the protection of very frail infants a partial cover for the tub, 21 1/2 inches in length, is provided to shield them more completely from outside air currents. It is provided with a thermometer, so that the temperature within the tub can be ascertained by the nurse at all times. Further, a brass nickel-plated frame covered by a removable linen cover is provided in the form of a hood. This can be set over the open space not covered by the metal lid in case of great air currents and extremely cold nights. This allows a free circulation of air to enter at the front of the canopy while at the same time preventing direct downpour of cold air onto the infant's head. The hood raises the temperature within the bed on an average of from 5° to 10° F., depending on the room temperature and current used, but does not interfere with perfect ventilation. The hood is made collapsible, and may be set at any angle desired, as may be indicated.

The hood is used in combination with the lid for very small or frail infants when a high temperature is desired or when the room temperature is more or less beyond our control, because of a defective heating system or extremely cold weather. Both are used when it is desired to heat this bed rapidly in an emergency.

The removable metal lid, which also holds the thermometer for temperature reading, is used alone for most cases, the length of time varying from a few days to several weeks. The hood and lid are both left off for the more mature cases and those being prepared for graduation from the heated bed to the nursery or home.

With the lid on it is rarely necessary to pass contact 4 of the rheostat to obtain a temperature of 90° F. in a room approximating a temperature of 70° F. When it is desired to heat the bed rapidly preparatory to its use, the rheostat may be set at point 6 with the hood and lid on until the bed is heated to the temperature that may be needed when it may be returned to points 2, 3, or 4, depending upon the fetal age and development of the infant.

As the infant develops it should be gradually prepared for graduation from the incubator by lowering the temperature of the bed by degrees to that of room temperature. This may cover a period of several days or weeks. At this time the lid may be removed. We have found it of advantage to remove the lid of the bed when the infant has developed sufficiently to thrive in the room temperature of 75° F., after which the temperature of the bed with the lid off can be left a few degrees above the room temperature by advancing the rheostat by one or two points. The temperature of the bed is now measured by placing a thermometer alongside of the baby within the sleeping bag or under the blanket.

It is our custom to cover the infant when in the bed with a light sleeping bag or light woolen blanket, in order to more completely stabilize its body temperature, as our beds are kept in a well-ventilated room. The sleeping bag should either be fitted with a flap, which can be used as a hood or a small bonnet should be warn or the blanket should be so applied so that it can be used as a head cover. Outer garments or covers should be applied loosely so as to allow of free movements of the extremities.

In order to use the bed rationally it is necessary to have an idea of the effect of the various factors influencing the crib temperature. To this end the following observations are offered for the guidance of the attendant.

Comparative Measurements of
Temperature in Heated Bed
Under Different Conditions

The temperature as read from the lid thermometer and that of a thermometer placed alongside the infant under a light blanket used as a cover will show variations which rarely exceed 1 to 3° F. at a room temperature varying between 70° and 80° F. The lid temperature will approximate the following:

Lid and Canopy On. -- 10° F. above the room temperature when on contact 2; 15° F. above the room temperature when on contact 3; 20° F. above the room temperature when on contact 4; 25° F. above the room temperature when on contact 5; 30° F. above the room temperature when on contact 6.

Lid On and Canopy Off -- 5° to 10° F. above the room temperature when on contact 2; 10° F. above the room temperature when on contact 3; 15° F. above the room temperature when on contact 4; 20° F. above the room temperature when on contact 5; 25° F. above the room temperature when on contact 6.

Lid and Canopy Off -- The temperature alongside of the infant under its blanket will average from 5° to 10° F. higher than the room temperature on contacts 2, 3, 4, 5, and 6 with a room temperature between 70 to 80° F.

As in all other care of these infants individualization should be the watchword and only by a careful observation of weather and temperature changes can the best results be obtained.

The maintenance of desired temperature for a given case resolves itself into a very simple problem if the above facts relating to the recording of the lid temperature is borne in mind, in that the only variable factors are the room temperature and air currents. The former in most hospital rooms will average from 65 to 75° F. throughout most of the day, and the ventilation of the room can easily be controlled. In most cases it is only necessary to change the rheostat one or two points at the extremes of the day, as at midnight when the temperature is likely to fall, and in the morning when the hospital temperature is again more uniform.

We require recording of the temperature of the room and bed at 6 A.M., 12 M., 6 P.M., and 12 P.M. In order to insure safety from extreme heat currents and extreme fluctuations in room temperature the point of the rheostat ward temperatures and humidity should also be recorded at these times (Fig. 88).

The degree of temperature to be maintained within the bed must of necessity vary with the individual infant and be dependent in part upon the infant's physical temperament. We rarely find it necessary to maintain a temperature above 90° F. for more than a limited number of hours even in extreme cases. In small infants it may be necessary to hold the temperature between 85 and 90° F. for several days. Most infants, after a few days, do best in a temperature ranging between 75° and 80° F., depending upon their development. An average of 76° to 78° F. will answer the latter needs of the better developed infants. It may be stated that fluctuations of 3° to 5° F. in the temperature in the bed during the course of the day have little detrimental influence on the infant's progress. Marked fluctuations are extremely dangerous (Fig. 142).

Ventilation. -- Ventilation within the bed is maintained automatically when the bed is heated. This is due to the fact that the air in the center of the bed is cooler than at the side walls, thereby causing the cooler air to pass into the bed at its center, then to flow to the floor, along the floor, to the side walls and then up and out at the sides. The direction of the air currents within the bed has a double advantage in that the infant receives the renewed fresh air for breathing while it is surrounded by the warmed air.

Humidity. -- Excessive drying of the air is prevented by the constant circulation through the bed of the free air of the room and by evaporation from a flat basin, containing baked porous clay (as used in water filters), over which water is poured to allow of evaporation. This is placed on the floor of the bed immediately under the baby basket. Varying with the degrees of temperature to be maintained within the bed, it is necessary once daily to supply from 8 to 16 ounces of water to replace that lost through evaporation.

Dangers. -- The dangers in the use of any heated bed which must at all times be avoided to insure success are:

1. Overheating and Refrigeration. -- Reading and recording of the room temperature, the rheostat contact and the bed thermometer at regular intervals throughout the day will furnish the necessary data to avoid these dangers.

2. Water Hunger. -- Fluids must be supplied to an amount not less than one-sixth to one-eighth of the infant's body weight every twenty-four hours as early as possible following birth. (See Feeding, p. 181.)

It is, therefore, necessary to control the temperature, ventilation and humidity of the bed, and to keep a careful supervision of the feeding, more particularly the fluid intake. Respiration must also be carefully watched in order to detect cyanosis and asphyxia sufficiently early to save the infant. This requires that these infants be observed day and night.

No attempt should be made to prevent heat loss entirely by keeping the air surrounding the infant at anywhere near its body temperature. Leaving an infant in such an environment would soon result in heat stagnation with resulting symptoms of heat stroke which is early evidenced by restlessness, rapid respiration and dry skin.

The bed temperature should be lowered gradually but steadily until it reaches 72° F. The best method of judging the infant's external temperature requirements is by taking the rectum temperature at stated intervals. The infant should be graduated from the incubator as soon as its general condition permits. It should then be kept in a clean, well-ventilated room, in which the temperature can be stabilized at about 70° F. The average time that a higher surrounding temperature will be indicated will vary between one and eight weeks and the hospital stay from two to ten weeks. "Mothering," in the form of exercise, and massage are essential to every premature once its physical condition permits handling. The same is true of needs for the strictest attention to its personal hygiene.

The infant should be discharged to its home as soon as possible for several reasons: (1) In a good home environment it will receive more individual care than in a general hospital; (2) the interest of the mother in the child must be maintained; (3) placing the infant at the breast is the best way of maintaining the mother's milk supply, if the breasts are still actively secreting; (4) in order to prevent "hospitalism" due to lack of "mothering" and a tendency to secondary infections.

The bed must be kept scrupulously clean.

The infant's bedding should be of such material that it can be destroyed when contaminated by vomit and excreta. Feathers are not practical. Untarred jute can be used for this purpose. The mattress should be covered by a heavy pad to prevent soiling.

All contact with infected cases and attendants must be avoided.

All visitors are best excluded.

The conservation of heat must begin immediately after birth.

The infant must be properly dressed; its head as well as its body should be protected.

The body temperature of the infant should not be allowed to go lower than 97° nor above 98.6° F. Daily fluctuations greater than 1.5° F. are dangerous.

The general care and feeding should receive the most careful attention.

Above all else care administered to the premature should tend to individualization.

Home-Made Heated Beds

Emergency Equipment. -- As many of the cases must be cared for in the home and in most instances without time or facilities to properly equip a nursery, every physician should have some definitive ideas on the construction of a bed which will meet exigencies of the individual case. We have already spoken of the general care and equipment of a nursery unit in the home. A number of practical emergency beds have been described, the specifications of a few of which will be given more in detail.

A small wash basket well padded inside and outside by quilting, into which is fitted a removable platform about 4 inches above the padded floor of the basket, makes a fair emergency bed. Beneat the platform in the floor of the basket hot-water bottles or bags are placed which must be refilled from time to time. The removal of the bags for refilling, which should be three or more in number and which are to be filled at different times, is facilitated by cutting an opening along the lower outer wall of the basket through which the water bags can be removed at will without disturbing the infant. A box can be built for this purpose to even better advantage.

Whether a box or basket is used it must be provided with some form of cover for three-quarters of its upper surface. This may be accomplished by using a heavy blanket or building a lid to fit.

In such a bed the infant must be provided with proper clothes as previously described to prevent undue heat loss.

This bed should be kept in a well-ventilated warm room, the temperature of which should range between 68° and 72° if possible.

Brown [26] describes the following practical home-made heated bed:

Take a 24-inch wicker clothes basket and pad the bottom with non-absorbent cotton to a depth of 8 inches. On top of this cotton fit a sheet of oilcloth, sewing the edges through the sides of the basket. On the oilcloth lay a double layer of white flannel and on the flannel a napkin of absorbent cotton. Take half a dozen of 12-ounce citrate of magnesia bottles with wire and rubber corks and cover them with flannel. These bottles are filled with water at 110° F. and hung on the inside walls of this basket. A thermometer hung inside should register a temperature from 80° to 90° F. all the time. At night an oilcloth is spread over the foot half of the top of the basket.

Electric-heating pads, protected by copper jackets, have been in use by the writer over a period of several years, and offer a valuable means of meeting emergency requirements. They are also valuable for use in the home where the temperature cannot be well regulated after infants leave the hospital station. Electric-heating pads have lost their popularity through the danger of fire following short circuit due to broken wires, and through the poor quality of the thermostat attachments of some of the pads. To avoid the danger of fire from short circuits in electric-heating pads, a copper receptable is used, 16 inches long, 13 inches wide and 1 1/4 inches high, into which a 12 x 15-inch heating pad is laid. To allow of a maximum radiation from the lid or upper surface of the same, the floor and sides are lined with asbestos sheeting, while the lid is not lined. The cord passes through a small rubber insulator at the side to prevent contact with the metal and injury to the cord. This simple device can be used temporarily in wards and homes where better facilities for care of this class of infants are lacking. It is to be placed in the bottom of a basket or crib, under the mattress or pillow (Fig. 143).

Litzenberg [27] has described a practical bed for home or hospital use for which the specifications are as follows. A box 24 inches long, 20 inches high, 18 inches wide. Eight inches from the bottom is a false bottom dividing the box into two chambers, the heating apparatus being in the smaller lower chamber and the baby in the upper one. The false bottom is the support for the bed of the baby and does not cover the whole bottom of the box, a space of 4 inches being left at one end for the circulation of hot air. The top of the box may be fixed on hinges, or to slide, which is better. There is a pane of glass in the top so that the baby may be watched, and there are two ventilating holes near the end of the cover opposite the place where the hot air enters. An ordinary pillow is laid on the false bottom for the bed. The incubator is heated by bottles filled with very hot water and placed in the lower chamber through a small door in the side of the chamber. Fresh air enters this door, passes over the hot bottles, is heated and ascends by way of the 6-inch space at the end of the box to the baby's chamber and out through the ventilating holes in the top, giving a constant supply of warm fresh air. A thermometer is placed in the incubator beside the baby, or better beneath the first fold of the enveloping blanket.

By watching this thermometer a fairly constant temperature can be maintained by frequent filling of the bottles. This is the method usually advised for heating. He has further devised a hot-air radiator made of ordinary 3-inch eaves-spouting. A temperature not varying 2 to 3° F., he states, is easy to maintain. The heat from the chimney of an ordinary lamp enters the spout radiator through an elbow 1 inch or 2 above the chimney. This elbow curves upward toward the box, which it enters by way of a hole in one end of the chamber where the spout divides into two parts to give more radiating surface. These two branches unite at the other end of the box, and the warm air passes out through a hole in the end without entering the chamber in which the infant is placed. Thus, the products of combustion in the lamp do not enter to injure the baby. The air for the baby enters by the door in the side of the box described before, and is heated by the hot pipes and ascends to the baby. Over the discharging end of the radiator is a cap with a hole 1 inch in diameter. This discharge hole being very small, keeps the hot air from rushing through without radiating its heat. The box can easily be made collapsible so that the whole thing can be slipped under the seat of a buggy and be set up complete in less than five minutes.

Specifications. -- Board 1 inch thick, 10 inches wide and 21 feet long. Cut six pieces 2 feet long and one piece 18 inches long. On four of the 2-foot pieces nail a small cleat, the full width of the board, 1 inch from each end. Eight inches from the edge of two of the 2-foot pieces nail a cleat parallel to the long way of the piece and on the same side of the piece as the small cleat. In the center of the 18-inch piece cut a hole 3.25 inches in diameter. Now set the pieces with the long cleat on edge. The cleats will face each other and be eight inches from the floor. Place one of the 18-inch pieces with the hole in it against the end cleats of the two side pieces and fasten them there by means of two hooks screwed into the short edge of the side pieces, the hook fastening in a staple or ring in the 18-inch piece. Fasten the other end in the same manner and then place the radiator in the two holes in the end. Now lay two of the 18-inch pieces in the long cleat, and you have the false bottom or bed support. The other 2-foot pieces with the cleats are now put together with the two remaining 18-inch pieces with hooks arranged as described, and when put together they are placed on top of the first set and securely fastened, thus making a box 18 x 20 x 24 inches. There now remain two of the 2-foot pieces which are fastened together with several cleats to make a top. A hole about 8 x 10 inches is cut near one end of the top for a window for observing the child, and still nearer the end are cut two ventilating holes about 2 inches in diameter.

Room Incubators

The room incubator or so-called giant incubator claiming to have all the advantages of little incubators without their inconveniences, was constructed in Lyon, France, for the first time in 1886 by H. Colrat. It consisted of a room 12 feet long and 8 feet wide. Its two main features were an attempt to hold a constant temperature, and a system of aeration permitting of renewing the air. It was, no doubt, a good innovation at that time.

In 1900 Arnaud, of Turin, introduced the hot-air room, and it found followers in other cities.

The incubator chambers built by Escherich and Pfaundler in Graz and Vienna, Brauer in Marburg and Langstein in the Kaiserin Auguste-Victoria House in Berlin are all of the same type with added improvements. They are completely enclosed cells of glass and metal construction, having sufficient room for two or more infant beds, obtaining the air from outside and are provided with automatic regulation of gas heating, ventilation and humidification. Between the cells and the nursery room there is a small space providing against cooling of the infant when the door of the incubator is opened. It is possible to change the clothing of the infants, to bathe them and to feed them in the room (Fig. 144).

Several clinics in the United States have built such rooms, among them Washington University, of St. Louis, and Michael Reese Hospital, Chicago. [See Footnote]

Some of the greater difficulties to be overcome are the automatic heat regulation, the cost of equipment and maintenance when only a small number of children are to be cared for, the distress caused the attendance when they are required to remain for a considerable period in the heated room, and most important the difficulty of individualizing the care of premature infants of different ages and stages of development.

The disadvantages of the larger incubator room have led in many clinics to their being discarded, among others that at Michael Reese Hospital. More practical is a room provided with special facilities for heating and ventilation which can be used in conjunction with individual heated beds.

In its primitive form an incubator room may be provided in a private home by heating the room to 75° to 80° F., at the same time making provision for moistening the air sufficiently by hanging wet clothes near the stoves or radiators. It is, of course, impossible to maintain a constant temperature and ventilation by such crude means, so that in conjunction with a more moderately heated room, 70° to 75° F., some type of individual bed for the further protection of the infant should be used.

A modification of the incubator room and doing away with some of its disadvantages has been installed in the Sloan Maternity Hospital, in New York, described by Dr. E. B. Cragin. It is possessed of many valuable features, such as filtered air, the absorption of air by an electric fan and the serial electric light heating. The disadvantages are to be found in the inability to individualize the infant care and the necessity for constant supervision (Fig. 146).

Selection of Method for Applying Artificial Heat. -- This must of necessity depend upon the facilities at hand. Every community should be supplied with the proper equipment for handling these infants. Such a station should be part of every maternity department. In institutions more especially designed for the care of infants, a more elaborate station should be supplied and wet nurses should be available.

Transportation Incubators

Probably the most important epoch in the life of the premature infant is that period between birth and the institution of some proper method for the prevention of refrigeration. It is the experience of all institutions receiving such infants that many of them are lost through carelessness in protecting them during the first hours after birth. The figures of Ylppö are illuminating on this point.

	Temperature 37 to 35 degrees. Died within the first month. Per cent.	Temperature 28 1/2 degrees. Died within the first month. Per cent.
Group I: 600 to 1000 gm.	66.6	100.0
Group II: 1001 to 1500 gm.	37.5	85.7
Group III: 1501 to 2000 gm.	21.05	60.0
Group IV: 2001 to 2500 gm.	5.88	20.0

By looking at the above table we may easily come to a one-sided conclusion that the mortality of the premature infants is in the first place influenced by the more or less severe initial cooling occurring after birth, and that therefore the mortality of the premature infants may be markedly reduced by painstaking care in preservation of heat.

A simple transportation incubator can be made by employment of an ordinary obstetrical bag with a false bottom. Hot-water bags or bottles can be carried in the lower compartment, and the infant in the bag proper. It is only necessary to make a sufficient number of 1/2-inch holes beneath the handle for ventilation. These should be reinforced by a metal rim so that they cannot collapse and cut off the supply of air. The fresh-air supply can be controlled by a metal slide covering these holes or by using corks. Eight larger holes should be made in the floor of the satchel, so that the heat can pass from the lower compartment into the upper copartment. These are best made close to the edge at the ends, so they will be less likely to be covered by the bedding (Fig. 147).

The De Lee incubator ambulance is a miniature incubator with a circulating hot-water system heated from the outside by an alcohol lamp. It is well ventilated and lighted by electricity. It is 21 inches long, 11 inches wide and 11 inches high (Fig. 148).

Welde has described a transportation incubator which is rather simple in construction (Figs. 149 and 150).

Heat is supplied by a thermophor or hot water bottles placed in lower compartment.

Footnotes

Giant Incubators

Specifications of Warm Room, Washington University, St. Louis. -- The fresh air from outside is driven in by an electric fan. It then passes over a system of steam coils enclosed in a closed steel cabinet, and is moistened by steam escaping from a small valve within the cabinet. Thermostat contact is used. The air makes a complete circuit of the heated chamber and passes into a closed shaft and enters the room through small registers located in the shaft. The used air leaves the room through the out-going shafts of the ventilating system. The room itself is insulated and the windows double. A thermometer and hygrometer are placed near a window and are visible from the corridor. A nurse records the room temperature and humidity on a chart every hour. To hold the room temperature at approximately 80° F. and humidity at 55° F., regular inspection is necessary because of the unsatisfactory working of the thermostat.

Specifications of Warm Room, University of California, San Francisco. -- The room is 9 by 11 feet, with an 11-foot ceiling. It accomodates five infants, the cribs being separated by glass partitions 4 feet high, extending 2 1/2 feet out from the side wall. Entrance is through double doors so placed that the outer one is closed before the inner one is opened. A large window at the opposite end admits ample light, and a closet is provided for gowns and supplies. Furniture consists of a dressing table, chair, and scales. The ventilating system delivers 200 cubic feet of air per minute, thus affording a complete change of air every five minutes. A thermostat and hygrometer maintain constant temperature and humidity of the entering air. The room is kept at 80° F. The infants arrive from the delivery room and are placed beside the radiator, additional heat being furnished by hot-water bottles if necessary. It is seldom necessary to keep them here longer than twenty-four hours, after which they maintain a fairly steady body temperature with the room at 80° F., and no additional heat in the crib.

Michael Reese Hospital Incubator Room. -- The specifications of this room are as follows. It is 16 1/2 feet long by 10 feet wide, with a plate-glass partition cutting off a vestibule 6 feet by 10, in which the nurse may stay out of the greater heat of the incubator room proper. The incubator room itself is a cube 10 feet each way, lined with cork, felt, and asbestos, besides the other normal coverings. There is a double window with separate double transom, and exhaust fan and an intake fan.

Bibliography

1. Denucé. Jour. de méd. de Bordeaux. December, 1857.

2. Clementovsky: Oesterr. Jahrb. f. Padiatrik, 1873, 3, 30.

3. Pasquad: La couveuse artificielle chez les nouveau-nés. Thèse de Paris, 1899.

4. Credé: Arch. f. Gynäk., 1884, 24, 128.

5. Winckel: Centralbl. f. Gynäk., 1882, Nr 1 bis 3.

6. Tarnier: Sie wurde 1881 in der Maternite aufgestellt und wohl zuerst in einer Arbeit von Auvard (Arch. de Tocologie, October, 1883) beschrieben.

7. Auvard: Arch. de Tocologie, 1883, p. 577.

8. Berthod: La couveuse et le gavage a la maternité de Paris, Thèse de Paris, 1887.

9. Hearson: Zit. nach Czerny-Keller, 1, 673.

10. Eustache: Jour. d. sc. méd. de Lille, 1885.

11. Diffre: Montpelier méd., 1896.

12. Lion: Zit. nach Czerny-Keller, 1, 673.

13. Pajot: Zit. nach Budin, manuel pratique d'allaitement, Paris, 1905.

14. Budin: Le Nourrisson, Paris, 1900.

15. Hutinel and Delestre: Revue mens. des mal. de l'enfance, 1899, 17, 529.

16. Finkelstein: Lehrbuch der Säuglingskrankheiten, Berlin, 1905, II Teil, s. 32.

17. Rommel: München. med. Wehnschr., 1900, Nr. 11.

18. Polanos: München. med. Wehnschr., 1903, Nr. 35, s. 1498.

19. Escherich and Pfaundler, L.: Mitt. d. Vereins. d. Arste in Steiermark, 1900, Nr. 3.

20. Colerat: Société des sciences médicales de Lyon, 1896.

21. Arnaud: La Sala incubatrice: Contributo allo studio della fisiopatologia dei neonati prematuri, Torino, 1900.

22. Cragin, E. B.: Jour. Am. Med. Assn., No. 11, 63, 947.

23. Ylppö: Ztschr. f. Kinderheilkunde.

24. DeLee: Obstetrics for Nurses, W. B. Saunders Co., Philadelphia, 1919.

25. Welde: Jahrb. f. Kinderheilkunde, 1912, 75, 551.

26. Brown, Alan: Arch. Pediat., No. 8, 34, 609.

27. Litzenberg: J. Minnesota Med. Assn., Minneapolis, 28, 87, 91, 1908.

Figures

	Fig 130. Warm tub with double wall jacket. First used by Denucé in 1857 and Credé in 1860.
	Fig. 131. Modified warm tub.
	Fig 132. Tarnier incubator.
	Fig 133. Finkelstein incubator.
	Fig 134. Reinach heated bed.
	Fig 135. Rommel incubator.
	Fig 136. Lion-type incubator (Couney model). The fresh air is forced through a large air shaft by an electric fan on the outside of the building.
	Fig. 137. Lion-type incubator. (DeLee model.)
	Fig. 138. Moll heated bed.
	Fig. 139. Hess water-jacketed infant bed.
	Fig. 140. Cross-section of Hess heated bed.
	Fig. 141. Cross-section of Hess heated bed showing direction of air currents.
	Fig.142. Showing variations in weight curve of an infant while in and out of a heated bed. The diet was unchanged between the dates September 19 and October 13.
	Fig. 143. Copper receptable containing pad.
	Fig 144. Incubator room. Escherich-Pfaundler system.
	Fig. 145. Heated room used as station for the care of premature infants (University of California, San Francisco, California). Showing individual cubicles, built on a shelf running across the room.
	Fig. 146. The Sloan Hospital incubator.
	Fig. 147. The obstetrical bag with false bottom designed by the author as a transportation incubator.
	Fig. 148. DeLee transportation incubator.
	Fig. 149. Welde transportation incubator. Inner case.
	Fig. 150. Welde transportation incubator. Outer case.