Changes in Intubation Rates and Outcome of Very Low Birth Weight Infants: A Population-based Study

(1)

Changes

in Intubation

Rates

and

Outcome

of Very

Low

Birth

Weight

Infants:

A Population-based

Study

Christian

F. Poets,

MD*

and

Brigitte

Sens,

BSc

ABSTRACT.

Objective.

There

have

been

indications

of a recent

decrease

in intubation

rates

of very

low

birth

weight

(VLBW)

infants

in Germany.

We wanted

to

quan-tify

this

decrease

and

analyze

its

effect

on clinical

out-come.

Methods.

Population-based

data

on the treatment

and

outcome

at hospital

discharge

from

a statewide

quality

assurance program were analyzed for 2001

VLBW

infants

(500

to 1499

g) born

from

1992

to 1994

in Lower

Saxony,

North

Germany.

Results.

The

proportion

of patients

not intubated

and

mechanically

ventilated

increased

from

7%

to

14%

in

infants less than 1000 g

and

from

28%

to 44%

in those

greater

than

or

equal

to

1000

g (P

<

.02

and

<

.01,

respectively).

This

increase

was

not

associated

with

any

significant

increase

in

adverse

outcome

such

as

death,

intraventricular hemorrhage, periventricular

leucomala-cia, or bronchopulmonary

dysplasia

(BPD).

Instead,

there

was

an

increase

in

the

proportion

of

infants

less

than

1000

g who

survived

without

BPD

(from

38%

in 1992

to

48% in 1994;

P

<

.05) and

a decrease

in the

proportion

of

infants greater than or equal to 1000 g in whom BPD

developed

(from

14%

to 9%; P

<

.05).

Conclusions.

The

data

from

a statewide

quality

assur-ance

program

show

a significant

reduction

in the

aggres-siveness

of the

treatment

of VLBW

infants,

which

was

not associated

with

an increased

mortality

or morbidity.

This

observational

study,

however,

cannot

define

whether

a more

selective

approach

to the

intubation

of

VLBW

infants

will

ultimately

result

in a better

outcome.

A randomized,

controlled

trial

would

be required

to

an-swer

this

clinically

important

question.

Pediatrics

1996;

98:24-27;

very

low

birth

weight

infants,

outcome,

quality

control measures.

ABBREVIATIONS. VLBW, very low birth weight; BPD,

broncho-pulmonary dysplasia.

trials.

This

is particularly

unsatisfying

because

both

procedures

may

have

serious

side

effects,

including

deciliation

and

necrosis

of the

tracheal

and

bronchial

mucosa

(which

can

occur

after

only

I hour

of

me-chanical

ventilation5),

ulceration

and

excoriation

of

the

nostril,

subglottic

ulceration

and/or

stenosis,

and

the

subsequent

development

of

bronchopulmonary

dysplasia

(BPD).8

Recently,

mechanical

ventilation

was

also

reported

to

be

an

independent

risk

factor

for

disabling

cerebral

palsy

in

low

birth

weight

infants.9

At

a major

plenary

session

of the

annual

meeting

of

the

German-Austrian

Society

for

Neonatology

and

Pediatric

Intensive

Care

in

December

1993,

Dr

Marcovich,

a neonatologist

from

Vienna,

Austria,

presented

uncontrolled

data

on

her

approach

to

the

treatment

of

VLBW

infants,

all

of

whom

were

out-born.

These

data

showed

a remarkably

low

rate

of

mechanical

ventilation

(with

only

14%

of VLBW

in-fants

admitted

from

1991

to

1992

being

intubated

at

24 hours

of

age),

a low

mortality

rate

(9%),

and

an

extremely

low

rate

of

chronic

lung

disease

(0%);

however,

only

25%

of her

patients

weighed

less

than

1000

g at

birth.1#{176}The

discussion

that

followed

this

lecture

showed

that

many

neonatologists

had

begun

to reconsider

their

indications

for the

intubation

and

mechanical

ventilation

of VLBW

infants.

We undertook

an analysis

of epidemiologic

data

to

study

changes

in

intubation

rates

and

outcome

pa-rameters

in

North

German

VLBW

infants

over

the

last

3 years.

We

wanted

to know

whether

there

had

been

a decrease

in intubation

rates

in this

region

and,

if so,

whether

this

decrease

was

associated

with

any

change

in

the

short-term

outcome

of

these

infants.

It is

common

practice

in

most

neonatal

units

in

both

Europe

and

the

United

States

to intubate

and

mechanically

ventilate

most

very

low

birth

weight

(VLBW)

infants;

recent

figures

on

intubation

rates

vary

between

79%

and

100%.14

This

practice

of

rel-atively

generous

indications

for

intubation

and

me-chanical

ventilation

of VLBW

infants,

however,

has

never

been

tested

in

large

randomized,

controlled

From the *Department of Pediatrics, Hannover Medical School, Hannover, Germany; and SLower Saxony Perinatal Working Group, Hannover, Germany.

Received for publication Dec 15, 1995; accepted Feb 21, 1996. Reprint requests to (C.F.P.) Abteilung Kinderheilkunde I, Medizinische Hochschule Hannover, 30623 Hannover, Germany.

METHODS

Each year approximately 670 VLBW infants are born in Lower

Saxony (North Germany) and admitted to I of 31 neonatal care

units. Approximately half the patients are admitted to one of five tertiary care centers, including two university hospitals. Two thirds of the remaining patients are treated in 10 hospitals that see between 15 and 30 VLBW infants per year. The remaining 16 hospitals admit less than 15 such infants per year.

In 1984 a statewide neonatal quality assurance program was implemented in Lower Saxony that aims to support both internal quality treatment and external data comparisons. As part of this program, information regarding perinatal conditions (eg, birth weight, gestational age, and Apgar scores), procedures (eg, intu-bation and mechanical ventilation and placement of central ye-nous lines), and diagnoses at discharge (eg, intraventricular hem-orrhage, BPD, death) is collected for all infants who are born in the state and weigh less than 1500 g at birth. These data are

docu-mented on a standardized form that is then anonymized and sent

to a central agency (the Lower Saxony Perinatal Working Group) for statistical analysis. Completeness of case recruitment is

at Viet Nam:AAP Sponsored on September 1, 2020

www.aappublications.org/news

(2)

ARTICLES

25 trolled by checking the neonatal data sets against those from a

corresponding statewide perinatal quality assurance program.1 For the purpose of this study, we used this database to analyze the following variables for all infants born between January 1992 and December 1994, weighing between 500 and 1499 g at birth, and admitted to a neonatal care unit: birth weight, gestational age, umbilical cord blood pH, mortality rate, duration of mechanical ventilation, number of infants who received prenatal steroids and/or exogenous surfactant, were born by cesarean section, were intubated during the course of their hospital stay, had central venous lines placed, received nasal continuous positive airway pressure, or had intraventricular hemorrhage grades III to IV,’2 cystic periventricular leucomalacia, and/or BPD (defined as oxy-gen administration beyond 28 days and/or typical radiologic changes). We decided to concentrate on the period 1992 to 1994 because we wanted to avoid any potential bias caused by the introduction of exogenous surfactant in Germany from 1990 to 1991. Data were analyzed for all infants and also separately for those with birth weights below and above 1000 g.

Statistical analyses were performed by using the linear trend test with Yates correction as a global test for all 3 years. If this proved significant (P < .05), comparisons were made between individual years using the test.

RESULTS

The

demographic

characteristics

of

the

infants

re-mained

constant

throughout

the

study

period

(Table

1).

There

were

an

additional

19 to

23 infants

each

year

who

died

in

the

delivery

room

(ie,

were

not

admitted

to the

neonatal

intensive

care

unit

and

were

thus

not

included

in

this

study),

but

again

this

pro-portion

did

not

change

significantly

during

the

study

period.

The

proportion

of infants

less

than

1000

g and

not

intubated

and

mechanically

ventilated

rose

from

7%

in

1992

to 9%

in

1993

and

then

to

14%

in

1994

(P

<

.02;

Table

2). This

increase

was

associated

with

a 35%

reduction

in

the

mean

duration

of

ventilation

from

23 days

in

1992

to

15 days

in

1994,

calculated

for

all

infants

less

than

1000

g,

regardless

of

whether

they

received

mechanical

ventilation.

The

proportion

of

infants

who

survived

without

BPD

increased

during

the

same

period

from

38%

to 48%

(P

<

.05).

All

other

outcome

variables

did

not

change

significantly.

The

proportions

of infants

greater

than

or equal

to

1000

g

not

intubated

and

mechanically

ventilated

were

28%

and

29%

in

1992

and

1993,

respectively.

The

proportion

then

rose

sharply

to 44%

in 1994,

an

increase

of 52%

(P

<

.01).

This

increase

was

associ-ated

with

a significant

reduction

in

the

number

of

infants

in

whom

BPD

developed

(P

<

.05;

Table

2).

All

other

outcome

variables

did

not

change

sigifi-cantly.

However,

there

was

a 40%

reduction

in

the

mean

duration

of ventilation

(from

8.3 days

in

1992

to 5.0 days

in 1994)

and

a significant

reduction

in the

proportion

of infants

who

had

central

venous

lines

placed

(P

<

.01).

A

comparison

of

the

data

from

the

five

tertiary

care

centers

in

the

state

with

those

from

the

other

hospitals

showed

that

the

proportion

of

infants

not

intubated

increased

in both

types

of hospital,

but

this

increase

was

more

pronounced

in the

smaller

hospi-tals,

possibly

reflecting

the

fact

that

the

latter

admit-ted

fewer

infants

with

birth

weights

less

than

1000

g

(Table

I).

DISCUSSION

This

analysis

of

population-based

data

from

the

Lower

Saxony

Perinatal

Working

Group

shows

a

50%

increase

in

the

proportion

of

North

German

VLBW

infants

not

intubated

and

mechanically

yen-tilated

in 1994

compared

with

1992

and

1993.

This

increase

was

not

associated

with

a

significant

in-crease

in the

number

of infants

who

had

an

adverse

outcome.

It was

also

not

associated

with

changes

in

obstetrical

treatment

(eg,

an

increased

use

of prenatal

steroids

or

more

cesarean

sections).

Instead,

there

was

a decrease

in

the

number

of

infants

in

whom

BPD

developed,

reaching

statistical

significance

for

those

weighing

greater

than

or

equal

to

1000

g at

birth,

and

an

increase

in

the

number

of infants

who

survived

without

BPD,

being

statistically

significant

in

those

who

weighed

500 to 999

g at birth.

This

is not

a randomized,

controlled

trial.

There-fore,

we

cannot

conclude

from

our

data

that

a

some-what

more

selective

approach

to

the

intubation

of

VLBW

infants

is better

than

a more

generous

intu-bation

policy.

Unfortunately,

however,

only

one

small

controlled

trial

has

so

far

been

published

on

this

issue.13

This

study

showed

a higher

mortality

in

selectively

intubated

infants

compared

with

rou-tinely

intubated

infants,

but

it is almost

impossible

to

interpret

because

of major

design

problems.’4

In the

absence

of

properly

controlled

data

on

indications

for

the

intubation

of VLBW

infants,

an

observational

TABLE 1. Demographic Characteristics of the Study Population and Compariso

Those From the Remaining Hospitals

n of Data From the 5 Tertiary C are Centers With

1992 1993 1994

N infants 665 664 672

Mean (SD) birth weight (g) 1126 (259) 1118 (254) 1115 (255)

Mean (SD) gestational age at birth (week) 29.2 (3.1) 29.0 (2.7) 29.1 (2.8)

Mean (SD) umbilical cord blood pH 7.3 (0.1) 7.3 (0.1) 7.3 (0.1)

N (%) infants born by cesarean section 539 (81) 551 (83) 558 (83)

N (%) infants on nasal continuous positive airway pressure but not intubated 25 (4) 33 (5) 38 (6)

N (%) infants not intubated and ventilated 142 (22) 149 (22) 230 (34)*

N (%) infants in tertiary care centers 343 (52) 304 (46) 31 1 (46)

N (%) infants not intubated in these centers 62 (18) 52 (17) 76 (24)

N (%) infants <1000 g in these centers 105 (31) 121 (40) 123 (40)

N (%) infants in remaining hospitals 322 (48) 360 (54) 361 (54)

N (%) infants not intubated in these hospitals 80 (25) 97 (27) 154 (43)t

N (%) infants <1000 g in these hospitals 100 (31) 102 (28) 100 (28)

*P < .05.

t P < .01, 1994 vs 1993 and 1992, respectively.

at Viet Nam:AAP Sponsored on September 1, 2020

www.aappublications.org/news

(3)

TABLE

1000 g

2. Data From Neonatal Data Sets for 1992 to 1994 Presented Separately for Infants With Birth Weigh ts Below and at or Above

1992 1993 1994

Birth weight 500 to 999 g

N infants 205 223 223

N

(%)

infants not intubated and ventilated 15 (7) 20 (9) 32 (14)*

N (%) infants with central venous lines 152 (74) 161 (72) 158 (71)

N (%) infants receiving prenatal steroids 117 (57) 119 (53) 118 (53)

N (%) infants receiving surfactant 122 (60) 136 (61) 130 (58)

N (%) infants who died before discharge 53 (26) 41 (18) 51 (23)

N (%) infants with BPD 79 (39) 81 (36) 71 (32)

N (%) survivors without BPD 77 (38) 103 (46) 106 (48)*

N (%) survivors without IVH/PVL 142 (69) 161 (72) 150 (67)

Birth weight 1000 to 1499 g

N infants 460 441 449

N (%) infants not intubated and ventilated 127 (28) 129 (29) 198 (44)t

N (%) infants with central venous lines 191 (42) 171 (39) 143 (32)t

N (%) infants receiving prenatal steroids 294 (64) 260 (59) 278 (62)

N (%) infants receiving surfactant 143 (31) 168 (38) 140 (31)

N (%) infants who died before discharge 21 (5) 22 (5) 25 (6)

N (%) infants with BPD 63 (14) 53 (12) 42 (9)*

N

(%)

survivors without BPD 377 (82) 367 (83) 383 (85)

N (%) survivors without NH/PVL 422 (92) 396 (90) 405 (90)

IVH, intraventricular hemorrhage (only grades III to IV); PVL, cystic periventricular leucomalacia; BPD, bronchopulmonary dysplasia.

*

P

< .05.

t P < .01, 1994 vs 1993 and/or 1992, respectively.

study

such

as

ours

can

at

least

generate

some

hy-potheses

with

regard

to the

effects

of different

intu-bation

policies

on

the

outcome

of

preterm

infants.

Thus,

our

findings

suggest

that

intubation

rates

for

VLBW

infants

in

Lower

Saxony

before

1994

may

have

been

unnecessarily

high;

ie,

they

argue

for

a

somewhat

more

selective

intubation

policy

in these

patients.

Our

data

also

demonstrate

a surprising

readiness

of

neonatologists

in

Lower

Saxony

to

change

their

intubation

policies

without

the

prior

publication

of

new

data

on

this

issue

from

controlled

studies.

This

probably

reflects

a considerable

uncertainty

about

“correct”

indications

for

the

intubation

of VLBW

in-fants

caused

by

the

absence

of controlled

data

and

hence

a high

degree

of susceptibility

to uncontrolled

data

such

as those

reported

from

Vienna

(see

above).

In this

regard

the

importance

of quality

control

mea-sures

in monitoring

the

effects

of changes

in

treat-ment

on the

outcome

of VLBW

infants

becomes

par-ticularly

evident.

Without

such

control

measures

the

effects

of

even

such

a widespread

and

significant

change

in treatment

as observed

in this

study

would

be difficult

to assess,

because

the

number

of patients

admitted

to each

individual

unit

is often

too

small

to

identify

reliably

the

potential

effects

of such

changes

on

outcome.

The

routine

monitoring

of quality

mdi-cators,

as

provided

by

the

Lower

Saxony

Permnatal

Working

Group,

can

thus

be

an

efficient

tool

for

trend

analyses

in this

specific

field

of health

care

and

may

help

further

to improve

the

treatment

of these

patients.

Our

data

on both

intubation

rates

and

mortality

in

1992

and

1993

are

similar

to, or even

slightly

lower

than,

those

published

by

other

investigators.

For

ex-ample,

in two

recent

studies

on the effects

of

prophy-lactic

versus

rescue

surfactant

therapy,

all

infants

born

at less

than

31 weeks’

gestation2

or

less

than

1351

g1 were

intubated

immediately

after

birth.

In

Cambridge,

United

Kingdom,

intubation

rates

from

1984

to 1989

were

100%

for

infants

less

than

1000

g

and

88%

for

those

weighing

1000

to 1499

g.4

Cone-sponding

figures

from

the

Vermont-Oxford

Trials

Network

for

1990

were

93%

and

70%,

respectively.3

Schwartz

et al,15 in a multicenter

study

on

the

effects

of surfactant

on

the

outcome

of VLBW

infants,

re-ported

mortality

rates

after

the

introduction

of

sur-factant

of 34%

for

infants

500 to 999

g and

8%

for

those

weighing

1000

to

1500

g.’5

Mortality

rates

re-ported

by

the

Vermont-Oxford

Trials

Network

were

similar

(34%

and

6%,

respectively).3

However,

com-parability

of

these

data

with

those

reported

in

this

study

is limited,

because

none

of

these

studies

was

population

based.

Although

guidelines

for

the

diagnostic

criteria

to

be

used

when

entering

data

into

the

neonatal

data

sets

have

been

issued

by

the

Perinatal

Working

Group’6

and

were

not

changed

during

the

study

period,

we cannot

be absolutely

certain

that

the same

diagnostic

criteria

were

universally

used

throughout

all

participating

hospitals.

This

may

be

particularly

relevant

to

a diagnosis

of BPD,

because

criteria

for

oxygen

administration

are

somewhat

subjective

and

may

have

varied

between

hospitals.

However,

we

are

not

aware

that

any

changes

in diagnostic

criteria

caused

by the

introduction

of new

monitoring

tech-nology

or

different

diagnostic

or

therapeutic

guide-lines

occurred

during

the

study

period.

In

conclusion,

this

analysis

of data

from

a

state-wide

quality

assurance

program

showed

a

signifi-cant

reduction

in the

aggressiveness

of the

treatment

of

VLBW

infants

in

a geographically

defined

area

that

did

not

result

in an increased

mortality

or

short-term

morbidity.

Nevertheless,

because

of

the

obser-vational

nature

of this

study,

it cannot

be

infened

from

our

data

that

a more

selective

approach

to the

intubation

of

VLBW

infants

will

result

in

a better

outcome.

Also,

we

do

not

know

whether

other

at Viet Nam:AAP Sponsored on September 1, 2020

www.aappublications.org/news

(4)

ARTICLES

27 changes

in

treatment,

such

as an

increased

tolerance

to high

carbon

dioxide

levels,

were

associated

with

the

observed

change

in intubation

policy.

A

random-ized,

controlled

trial,

although

probably

difficult

to

perform,

would

be

required

to

answer

these

ques-tions.

ACKNOWLEDGMENTS

We thank P. Wenzlaff for performing the statistical analyses and B. Bohnhorst, MD,

J.

Freihorst, MD, H. von der Hardt, MD, and V. A. Stebbens, BSc, for their helpful comments on the manuscript.

REFERENCES

I

.

Bose C, Corbet A, Bose G, et al. Improved outcome at 28 days of age for

very low birth weight infants treated with a single dose of a synthetic

surfactant. JPediatr. 1990;1 17:947-953

2. Egberts J, de Winter JP, Sedin G, et al. Comparison of prophylaxis and

rescue treatment with curosurf in neonates less than 30 weeks’ gestation: a randomized trial. Pediatrics. 1993;92:768-774

3. The Investigators of the Vermont-Oxford Trials Network Database Project. The Vermont-Oxford Trials Network: very low birth weight outcomes for 1990. Pediatrics. 1993;91 :540-545

4. Greenough A, Morley CJ, Roberton NRC. Acute respiratory disease in the newborn. In: Roberton MRC, ed. Textbook ofNconatologi. Edinburgh,

Scotland: Churchill Livingstone; 1992:385-504

5. Nilsson R, Grossmann G, Robertson B. Lung surfactant and neonatal bronchiolar lesions induced by artificial ventilation. Pediatr Res. 1978; 12:249-255

6. Kirpalani H, Higa 1, Perlman M, Friedberg J, Cutz E. Diagnosis and

therapy of necrotizing tracheobronchitis in ventilated neonates. Crit Care Med. 1985;13:792-797

7. Joshi VV, Mandavia 5G. Stem L, Wigglesworth FW. Acute lesions

induced by endotracheal intubation. Am / Dis Child. 1972;124:646-649

8. Gau GS, Ryder TA, Mobberley MA. latrogenic epithelial change caused

by endotracheal intubation of neonates. Early HIItiZ Dcv. 1987;15:221-229 9. Pinto-Martin JA, Riolo 5, Cnaan A, Holzman C, Susser MW, I’aneth N.

Cranial ultrasound prediction of disabling and nondisabling cerebral

palsy at age two in a low birth weight population. Pediatrics. 1995;95:

249-254

10. Mutschier U. Sanfte Pflege des Frtihgeborenen. Hautnah Pldiatr. 1994;

6:143-154

1 1

.

Peltner HU, Sens B, Rienhoff 0. Zusammenfuhrung perinatologischer und neonatologischer Datens#{228}tze: Eine zus#{228}tzliche Moglichkeit der Qualitatssicherung in der perinatalen Medizin. In: Dudenhausen JW, ed. Perinatale Medizin in Deutschland. Munich, Germany: Quintessenz; 1992:59-66

12. Papile L-A, Munsick-Bruno G, Schaefer A. Relationship of cerebral

intraventricular hemorrhage and early childhood neurologic handicaps.

I

Pediatr. 1983;103:273-277

13. Drew JH. Immediate intubation at birth of the very-low-birth-weight infant. A,n

I

Dis Child. 1982;136:207-210

14. Tyson JE. Immediate care of the newborn infant. In: Sinclair C, Brackan MB, eds. Effective Care of the Newborn Infant. Oxford, England: Oxford University Press; 1992:21-39

15. Schwartz RM, Luby AM, Scanlon JW, Kellogg Rj. Effect of surfactant on morbidity, mortality, and resource use in newborn infants weighing 500 to 1500 g. N EngI JMed. 1994;330:1476-1480

16. Perinatologische Arbeitsgemeinschaft Niedersachsen. Kurzanleitung

zum Ausfullen des Neonatologischen Erhebungsbogens. Hannover, Germany: PAG; 1989

NURSE

PRESCRIBING-WHAT

NEXT?

. . .

The Medicinal Products: Prescribing by Nurses Act (1992)

is in

existence,

per-mitting

certain

groups

of

nurses

prescribing

rights

for

a

limited

formulary

of

products.

Why

should

the

nursing

profession

be

seeking

prescribing

rights?

Meet-ing

chairman

Dr

Graham

Burton

(Zeneca)

identified

the

trend

to

increasing

spe-cialization

of the nurse’s

role,

and

that

many

more

nurses

undertake

postgraduate

research

in

their

chosen

specialization,

leading

to an

increased

amount

of clinical

responsibility

in

practice.

J R Soc Med. 1996;89:117.

Noted

by

J.F.L.,

MD

at Viet Nam:AAP Sponsored on September 1, 2020

www.aappublications.org/news

(5)

1996;98;24

Pediatrics

Christian F. Poets and Brigitte Sens

Population-based Study