Mukta M. Jain, Arvind
Shenoi and H. Paramesh
From the Department of
Pediatrics, Lakeside Institute of Child Health, 33/4, Meanee Avenue,
Ulsoor, Bangalore, 560 042, India.
Correspondence to: Dr.
H. Paramesh, Pediatrician-in- Chief, Lakeside Institute of Child
Health, 33/4, Meanee Avenue, Ulsoor, Bangalore, 560 042, India.
Manuscript received: May
9, 2000, Initial review completed: June 2, 2000;
Revision accepted: March
6, 2002.
Nursing a neonate on
the standard oxygen head-box poses several problems related to access,
inlet size, nebulisation, oxygenation and nasogastric feeding, During
procedures such as insertion of a nasogastric tube, cleaning up of
vomitus, aspiration of nasal mucosa or just patting the baby to sleep,
the head box has to be lifted off entirely thus affecting oxygenation
causing hypoxemia. Hence an attempt has been made to alter the design
of the head box which helps in carrying out the maneuvers without
lifting the head box and with minimal change in Fi02 thus maintaining
uniform oxygenation. Neonates nursed in this headbox do not show
retention of CO2 even at low flow rates.
Keywords:
Neonate, Oxygen head box
A head box is a device used to deliver oxygen to neonates who are hypoxic.
Nursing a neonate on the head box has several problems(1), the most important being (i)
the inability to maintain uniform oxygenation while carrying out maneuvers such as
insertion of a
nasogastric tube, cleaning up of vomitus, feeding or putting the baby to
sleep, (ii) inability to ascertain the FiO2 without the FiO2
analyser, (iii) difficulty in administering nebulized
medications, and (iv) inability to use oxygen flow rates of less
than 2L/minute.
Many different brands are
available in the market. They lack in standardization in respect to
size, shape and volume. This article highlights a head - box design
which overcomes these shortcomings and aims at obtaining reproducible
desired concentrations of oxygen.
Fig. 1. The New Oxygen
Head Box
Subjects and Methods
The deficiencies of the
existing head-box relating to the access, inlet size, nebulization,
oxygenation, nasogastric feeding, oxygen concentration were studied and
an attempt was made to improvise on them. The new head box (26cm × 23cm
× 20cm) was compared with the common one available in Bangalore
measuring 24cm × 15cm.
The inlet size could be
altered using a sliding door to facilitate its usage for neonates, to
infants up to one year of age. A large lid was provided on the top for
easy access while carrying out nursing maneuvers. The head box could be
used with low oxygen flows with this lid, when kept open. A nebulizer
holder was fixed on the left wall of the box for keeping the nebulizer
cup erect. A small opening was provided on the top left corner of the
head box for fixing the syringe which could be connected to the
nasogastric tube and facilitate tube feeding. The oxygen inlet was
provided on the right side with a baffle to provide uniform oxygenation
throughout the box (Figs 1-2). A side port was also provided on
the right side to adjust the concentration of oxygen in the new head box
with the side port full open, half open, and closed.
The head box was tested on 4 term healthy
neonates admitted for transitional nursery care. The end tidal CO2 was
monitored in these neonates using OHMEDA Datex Engstrom Cardiocap-II TM
CG-series capnograph. The end tidal CO2 was noted at no flow, 1 L/min
and progressive 1 L/min increment till 10 L/min. The capnographic
readings were taken when the respiratory rate of the infant matched that
on the capnograph and was steady for 5 minutes with the top lid
Table I__Concentration of Oxygen Delivered in the Conventional and New Head Box
Oxygen Flow
(L/min)
|
Conventional
Head Box
|
New Head Box
|
|
|
Side port
fully closed
|
Side port
half open
|
Side port
full open
|
|
(%)
|
(%)
|
(%)
|
(%)
|
0 (room air)
|
21.0
|
21.0
|
21.0
|
21.0
|
1
|
27.2
|
49.2
|
46.4
|
44.8
|
2
|
'
|
'
|
'
|
'
|
3
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
'
|
10
|
52.2
|
79.5
|
62.8
|
53.0
|
Table II-Capnographic Data in New Oxygen Head Box
Oxygen Flow
(L/Min)
|
Mean End Tidal CO2 (mm of Hg)
|
|
With lid closed
Mean (SD)
|
With lid open
Mean (SD)
|
Head box with room
air with baby
|
28.08
|
24.62
|
Head box with oxygen
with baby
|
1 lit
|
25.35
|
20.08
|
2 lit
|
28.47
|
22.44
|
3 lit
|
30.03
|
26.08
|
4 lit
|
27.69
|
20.14
|
5 lit
|
28.86
|
23.24
|
6 lit
|
26.13
|
21.41
|
7 lit
|
27.69
|
25.22
|
8 lit
|
27.30
|
22.12
|
9 lit
|
27.69
|
20.02
|
10 lit
|
28.47
|
24.14
|
open and closed. The
means were compared using student ‘t’ test and ANOVA (Analysis of
variance) and the value of P < 0.05 was taken as significant.
Results
The new head box was
found to be convenient in the following ways. The inlet size could be
altered, access to the head end of the baby for carrying out different
maneuvers became easy, nebulization could be given uniformly,
nasogastric feeding was easier, concentration of oxygen could be altered
as described and there was no cooling of the baby.
The concentration of oxygen delivered in
the commonly available head box and the new head box with the side port
closed, half open and full open were compared as depicted in Table I
and found to be significantly better (F = 20.16, P < 0.001) in the
new head box as compared to the commonly available head box. The end
tidal CO2 readings are depicted in Table II. The neonates did not
show
statistically significant
difference in end tidal CO2 (P > 0.05) suggesting that there was no
CO2 retention at low flow oxygen.
Discussion
A head box is a device to
deliver oxygen to a sick neonate. The design of the commonly available
head box has a few fallacies which we have tried to circumvent in the
new one. The following design features have helped in better oxygenation
without the risk of hypoxia. Altering the inlet size using a sliding
door prevents restriction of movement and airway compression on large
babies. Access to the head of the baby for carrying out nursing
maneuvers is facilitated by the large sliding lid on the top. This lid
has an added advantage that it can be kept open at low flow rates to
prevent CO2 accumulation(2). A nebulizer holder helps in holding the
nebulizer cup upright and facilitates nebulization. A syringe holder
holds the syringe while feeds gravitate to the baby. The major advantage
is that the nurse need not be present throughout the procedure, nursing
time is reduced by half and efficiency improves. The baffle creates eddy
currents and provides uniform oxygenation throughout the head box.
Another problem faced by many units is the non-availability of the FiO2
monitors or the cells for such monitors. The side port was designed with
the idea of delivering a particular concentration of oxygen at a given
flow rate. The authors also would like to emphasize that an FiO2 monitor
is essential for rational oxygen therapy and a standardized headbox
reinforces this concept.
Jain and Johri(3) stated
that the concentration of oxygen was markedly affected by the capacity
of the box, oxygen inflow rate, window size; size, force and direction
of oxygen jet. The significant features in their study was that oxygen
concentration was markedly increased by increasing the oxygen inflow and
by decreasing the head box volume and the window size. The new head box
design incorporates these findings.
Our study concentrated on the oxygen
inlet which, in the common head box was in the centre of the back wall
of the head box directed towards the head of the neonate. This cools the
head of the baby. Secondly the oxygen inlet was opposite the head box
inlet causing the oxygen to stream out resulting in low FiO2, even at
very high flow rates. In the new box, the inlet was attached to the
right wall with a baffle which creates eddy currents resulting in
uniform and higher FiO2 through the box even at low flow rates. The size
of the window was also helpful in determining the concentration of
oxygen delivered. The lid helped in easy access to the head end and when
kept open at low flow rates prevented CO2 retention in the neontate. Our
study has
lead to CO2 retention
even at low flow rates either with lid open or closed. The current head
- box thus could be used effectively in nursing the head end of the
neonates and infants without significantly altering the oxygen
concentration. It is also cost effective. The cost is around Rs. 200
more than the standard head box of similar dimensions.
Acknowledgement
The authors wish to thank
Medilek Instruments for the help rendered in manufacturing the head box,
all the post graduate students, Dr. Salim A. Khatib and Sister, Gangamma,
Nursing Incharge of NICU of Lakeside Institute of Child health for their
critical analysis and valuable suggestions. The authors also acknowledge
the help of Mr. Ashok Murthy and Mr. Prasad of Moola Technologies
limited for their assistance in conducting this study.
Contributors:
MJ conducted the study and drafted the paper. AS designed, helped
conduct the study and drafting of the paper; he will act as gurantor of
the paper. HP guided the study and the overall drafting of the paper.
Funding:
None.
Competing interests:
None stated.
|
Key
Messages |
• The new head box
design provides access to the head of the neonate for nursing,
nebulization, and nasogastric tube feeding.
• The FiO2
could be roughly ascertained even without an oxygen analyzer. This was
facilitated by locating the oxygen inlet port with a baffle on the left
side wall of the head-box.
• Neonates nursed in this head
box do not show CO2
retention even at low flow rates of oxygen.
|
