Neonatal infant mortality

Before and After Ar,r,a~ (Prom

tlx

NEONATAL INFANT MORTALITY the Use of the Air Lock for the Treatment Infants in a Large Maternity Hospital

B~oxso~r, Depcwtmcnt

M.D., of

.ISD

Pediatrics /hiuersity

SISTER of

Xmu

the St. College

AKGELIQYE,

Joseph’s of

Clddtrt~‘s

of Newborn

IIous~ox, Uospitnl

Tmas and

the

lin,dor

~CdiCi?ke)

N 1950 and 1951, report+ 2 were made on a new method of oxygenation of the newborn infant as a means of treatment during resuscitation, and the statement was published that “The mortality rate in a large maternit hospital has been lowered approximately 25 per cent from a slight reduction in the premature delivery rate and t.he use of the positive pressure oxygen air lock in resuscitating asphyxiated newborn infants.” Nineteen fifty-two marked the third year the Bloxsom Air Lock has been in use in the St. Joseph’s Maternity Hospital in Houston where 6,000 and more deliveries occur each year. Two air locks are in use in the delivery rooms and three air locks are in use in the premature and recovery nurseries. These air locks have been widely used, particularly during the year 1952. Ten per cent of the infants who do not breathe spontaneously are placed in the Bloxsom Air Lock; 50 per cent of the infants are at term and the remainder are l)remature. In January, 1953, an adverse critical evaluation3 of the air lock from New York City appeared, based on attempts to make the air lock function as a barospirator for apneic adult dogs. Such a function, of course, was never intended or claimed for the air lock. It was thought, therefore, at this time it would be interesting to compare the mortality rates of the term infant and the premature infant of 1919, the year before the air lock appeared, and 1952, the year the air lock has been generally used, in an effort to determine if there has been any lowering of the infant mortality when the only change in the treat,ment of the handicapped newborn infant in the hospital has been the use of the air lock. Table I shows the neonatal death rates of all infants for the years 1949 and ‘1952 in the St. Joseph’s Maternity Hospital in Houston during the first forty-eight hours of life. The mortality rate of the term infant delivered in the St. Joseph's Maternity Hospital in Houston during the year 1952, the third year the ail lock was in use, fell from 63 per 10,000 term deliveries in 1949 to 37 per 10,000 term deliveries in 1952, a reduction of 41 per cent. This represent.s a salvaging of 26 term infants in 1952 from a previous loss of 63 term infants I

647

WEIGHT 450 YEAR

1 LIVING

1949’

3

1952

3

T O 1,000

I-

‘DEAD

/

(8%)

36 lOc,,, (!I%,) 31 8%

1,001 1

L,V;NG

(920/o)

19

(467b)

(9lr/F,

23

(X’o/,)

1

I

DEAD

)

1,501

1

11

I

DELIVERED

377 4.5”

I

“,ooo

1 ___----2,001

bEAD

/

TO

LIkING

2,500 j

DEAD

‘l

22%

6%

1949 1952

TO

L&h-G

8%

TOTAL YEAR

(GRAMS

T O 1,500

PREMATURE

I

293 384

64%

INFANTS

LIVING ___-.--

(77.72Cl ( 84.96%

DF,AIJ

I

.j 1 herease Prrcentage

84 68 in 1952 decrease

(22.23%~ (15.04~~

j / 7.“iy$ ‘1.‘.5% .- I

The mortality rate of the premature infant delivered in the St. Josrph’s Maternity Hospital in Houston during the year 1952, the third year the ilit’ lock was in use, fell from 2,228 per 10,000 premature infant deliveries in 1949 to 1,504 per 10,000 premature infant deliveries in 1952, a reduction of :lZ.+J per cent,. This represents a salvage of 724 premature infants out 01’ iI t’trrmrr. loss of 2,228 premature infants per 10,000 premature infant drlivcries. The only difference in handling of the premature infant between 1949 illIt I!):,:! has been the widespread use of the air lo~lr for early iltltl cont~inurtl ospge~lation in order to gain time for sur\-ival. Comment Tt is believed premature infants

that some part of the reduction in neonatal mortali@ 01’ has been due to a slight decrease in incidence of the very

sma.11 premature infant with a slight increase in the incidence of the preHowever, in t,he premature innlature infant weighing 1,501 to 2,500 grams. fant that weighs from 1,501 to 2,000 grams, the neonatal mortality dropped from 24 to 16 per cent, a drop of 33l/s per cent. In the premature infant weighing from 2,001 to 2,500 grams, the neonatal mortality dropped frown 6 lo 4 per cent, a drop of 3354 per cent. The reduction in mortality in the neonatal period of the premature infant delivered in the St. Joseph’s Jlaternity Hospital in Houston in 1952 when the air lock was used extensively has been accomplished by the use of the air lock chiefly, and not essentially through an increase in the incidence of larger premature infants being clelivered iu 1()lj‘) . I -. Apparently two mechanisms operate when the air lock is used for proccssing the handicapped newborn infant. The first mechanism is early and ral)id oxygenation. A chart of the rate of oxygenation of an anoxic infant is shown in Table III. ‘I’MKE

1 I I.

OXYGEN

SATURATION READIXGS OBTAINED BY AN INFANT BY AN APNEIC INFANT BEING OXYGENATED

(~6. RICSPIIL~TI~NS

OXIMETER IN THE AIR

ON IIVITLITJON LOGIC

-__ .Ifotl~rr--BcZn,nzlsia.Morphine Mepcridine Paraldehyde Phenobarbital

.lLinutcs After

Total

Sedation

sulfate hydrochloride

300

sodium

Delivery.-

Oximeter Sntwation.-

2 grains mg.

30 C.C. 25 grains Readings in Percrntngc .50

50 65

7 (Irrqplar

respirations

started)

Pressures x5 I.B. 9 10

14 1 Ci

20

of O.~~y,q~~r

15

3 (Adjustment oximeter) 5 ( In air lock with cycling ) 6 (rnfant made initial gasp) 9

~

O,uer 36 Hours.-

in -dir

LOG,&-

3 rJ3.

77

83

75 83 86 87

36 9-l 9.5 97

1 LB.

96 95 104

The second mechanism is believed at the present time to be an increased I*atc of metamorphosis of the low cuboidal cells lining the alveol:lr sac’s l)ronght about by pressure changes in the air lock, whereby these cells change I o a flattened type providing a greater surface for the exchange of oxygen :Ind carbon dioside.4 Such an increased rate of metamorphosis a,lso m;~y prcvent leakage by the pulmonary capillaries into the alveolar sacs, and at the same t,ime provide a means of maintaining the pulmonary pressure.

Summary 1. The reduction in the forty-eight hour neonatal death rate in 1952 in the St. Joseph’s Maternity Hospital has exceeded considerably the original optimistic report. 2. There has occurred a reduction in the forty-eight hour neonatal death rate of the term infant in the St. Joseph’s Maternity Hospital in Houston from

63 per 1.0,OOOtern1 deliveries in 1949 to Xi per 10,000 tern1 dcliveriw in 19% because of early and rapid oxygenation to wt,ahlish respirations. This is ;I I-(‘duction of 41 per cent and represents :I si~lvage of 26 infants from :I I’OIWLC~ loss of 6.3 tertn infants, 3. There has ownwwl a rcduvtioll in the I’orty-eight hour neonatal (leittll ratp of the prernaturc infant in t?w St. ~Joscq~h’s Matcrnit,y Ilospital in Tlbuston frown 2,228 deaths per 10,000 prematur(~ drlivcrics in 1949 to 1,504 deaths TM 10,000 premature dt~liverics in 1952, rc>tluvtion of :32.:5 per cent. This repw sents a salvaging of 724 prrlnatnw infants front :I Cornier loss of 2,238 pr(‘mature infants per 10,000 pwnlaturc infant ilelivtric3. 4. The primary C~IISW for this wrluc*tion :IW hclir\-rd ilt the prc~se~lt t.ilrlt, to be (1) the rapid oxygenation 01 tltth illlc)sic: infant 1)~ the air look atl(l (2) an increased rate of r,lrt,anlc)l,J)hosi~ of the low ~ul)oidal cells lining the alveolar saw bought al)ont 1)~ ~~~~IIY~ (dhangcs in the air lock wherrhp these cells change to ii flatte~~etl ty~)tb (*;ltlsiflg ati intwased e%ciency of ihc lungs through providing :I gt*eater surril(‘(’ of tht, c*tlll~ lining ihe alveolar* sac’s for t,he exchange of nsygen and cnrlwn tlic)sidti. i

References 1. 2. 2. 4.

Hloxsom, A.: J. Pediat. 37: 311, 19511. Bloxsom, A.: J. A. M. A. 116: 1120, 19.5 I. Apgar, I’., and Kreiselman, .I.: AM. J. 0m1~. Hloxsom, A.: AM. J. ORST. & (:YNEC. 66: 1170,

6; (i~xrx’. 19X.

65:

45,

1953.