Id~nff' Pedlatr, 45 : 183, 197g

FLUID A N D ELEGTROLYTE T H E R A P Y !N SURGICAL NEONATES

I I ~ A c t u a l E s t i m a t i o n

KI. :~I:.,~^ YADAV

Ch~ndrgarh

The impor tance of fluid and electrolyte

therapy in the m a n a g e m e n t of surgical neonates where oral adminis t ra t ion is not

feasible needs no emphasis. Intravenous

fluid therapy comprises water and electro- lytes, blood and substances which provide nutritional requirements . The purpose of this paper is to discuss the actual estimation

of water and electrolytes required in the

surgical problems of newborn infants based on the author 's experience in a children's

centre in Australia.

Dis tr ibut ion o f f lu id a n d e l e c t r o l y t e s in a n e w b o r n i n f a n t

A full t e rm newborn has excess of body

water (10 per cent of total body weight), which is normal ly excreted during the first few days of life (Fink and check 1960).

The relationship of extracel lular to entra-

cellular water is 46 per cent to 54 per cent in newborn, that in the adul t being 40

per cent to 60 per cent. Since the body

surface area of the infant is relatively

larger and the respirator3" and metabolic

rates higher than the adult , insensib!e water loss is relatively more. In a single day, the water excretion o f an infant approaches 50

pe rcen t of his extracellular fluid, whereas

in the same period an adult excretes only 14 per cent. The above factors thus lead

to a greater water requirement per unit of

body weight in infants than in adults. Tile kidneys of newborns are efficient, so

far as urinary excretion is concerned, on the basis of total body water, but they

(especially of a p rema tu re infant) are unable to concentrate and conserve fluid and electrolytes. This renal ~mmaturity restricts their reponse to the condit ion of

stress and increased metabol ic demand. Thus the ur inary specific gravity may

remain low (1015) inspire of serious fluid intake deficiency. Mild over hydrat ion can lead to congestive failure because renal excretion is l imited due to a decreased

glomerular filteration rate. When the

infant becomes 3 to 4 weeks of age he starts behaving as an older child. The

newborn passes 25-30 ml of urine daily during the first few days of life, which

goes up to 100-150 ml by the end of the first week and at the same t ime the osmola- lity falls from 400-500 mosm/L to about

100 mosm/L. Since the cellular mater ial is

smaller in proportion at birth for per kg body weight, the sodium content is 5t3 per cent higher and the potassium 20 per cent

lower than in adults. Keeping in mind

the above factors, fluid and electrolyte therapy in neonates should be estimated as shown below.

*From the Deparment of Surgery, Postgraduate Institude of Medical Education and Research, Chaudigarh. Received on I7, 1977,

(a) Estimation of fluid and electrolytes where repair o! dtficit is not required.

After the first few days of birth, when

1114 INDIAN JOURNAL OF PP.DIATRIC$

the body water of the new born infant is equilibrated, the maintenance requirement of fluid increases. Over the following few weeks, depending upon the metabolic

:~ctivity, the fluid given is approximately 100 ml/kg/24 hours, as advised by Darrow (1959). Table 1 shows ttle required amount

VOL. 45, No. $ ~

of fluid and electrolytes given to a neonatl where oral fluid is not fcasible.

(b) Estimation of fluid and electrolytes wheel repair of deficit iJ required.

The new born baby losses fluid rapidly i . the presence or gastrointestinal obztruc..

- ~ A ~ T a b l e 1. Fluid and Electrolyte Therapy in a Neonrtte.

Fluid~ Fluid required Age of the Neonate ml/kg/24 hours

1 day 40

2 days 50

3 days 60

4 days 70

5 days 80

6 days 90

7 days i 00

I week- - I month 110-120

Electrnlyte Daily Requirement Form in which .eiven i

Na-k- 2-3 mEq/Kg body wt. 1/5 in normal saline

K + 1-2 mEq/Kg body wt. KC1 solution 1.5ml

C I + 2-3 mEq]Kg body wt. 1/5 normal saline

Ca+-k- 300mgm/kgm/body wt. Ca-gluconate 10% saline

M g + + 0.2ml/kg/body wt. ~0% solution of Mg-sulphate

Mg 509'0 5 solution 8meq sulphate .2ml/kg

In neonates the pre-existing loss is almost never necessary except in neglected duodenal obstruction. Only" when drip longer than I week.

CADAV~ F L U I D AND ELI~CITROLY'I'E TIIE, RAPY IN

ii0n,.vomiling, peritonitis and ruptured 0taphalocoel'-,. The assessment of Iluid loss

jscompared to elder children is extremely dl,~cult. In older children urine volume and specific gravity are reliable clinical guides for estimation of fluid loss, but as mentioned before, the newborn has limited concentrating ability and he continues passing dilute urine in the face of hypetos- mola r plasma. Tim measurement of body weight over a specific period, though help- fill. fails to detect the redistributio,D of Iluid volume, as in the case of intestinal obstruction where a large amount of fluid collects in the lumen of the gastrointestinal t r a c t . Thus assessment of the pre-existing 10ss is necessary and we base it on clinical

SUkGICAI,, NEONATES 185

and laboratory findings. As given in Table 2, the importance is placed on observed loss of body weight, state of peripheral circulation, skin turgidity, urinary output (the normal in an adequately hydrate d infant being 1.2 ml/kg houri, serum elr lates, and blood ulea. The baematocrit estimation is unreliable due to the large variation o f haemoglobin in newbor,As and infants.

The actual estimation of fluid require- ment is made on the severity of dehydra- tion, electrolyte deficit and over this the maintenance amount of fluid is added. The estimated deficit amount of water is replaced during the~first 4 hours. The

T a b l e 2. Clinic Fea,wea fo~ Assessment O/Degree Hyc&ation.

Dehydration Clinic Signs

Mild dehydration (when loss is 2�89 per cent of body weight) (clinically recognisable) moderate dehydration when loss is 5 per cent of body weight.

Obvious dehydrat ion

Incipient and actual cirulatory failure

i

Thirsty dry mouth - -warm skin -- fantanelle soft - oliguria - Restlessness - -dry tongue and mouth -- eyes sunken

--Fontanelle depressed - -marked oliguria - - e x t r e m e dryness of

mouth and tongue

--Eyes staring and swollen -- Fontanelle markedly

sunken and depressed - - R . p i d and feeble pulse --Cyanosis of extremeties - -Mark loss of skin elasticity

cold skin, fever.

Amount of Fluid Required

50ml/kg body weight

75ml/'kg body weight

lOOmllkg

186 INDIAN JOURNAL OF PEDIATRICS

types of fluid used at our centre are men- tioned in Table 3.

Mostly the deficit fluid is replaced with the balance of the eJectrolyte solution, suci, as, Ringer's lactate and, subsequently, modifications are carried out by clinical response, in cases where immediate restoration of vascular volume is required,

whole blood or plasma infusion is given. Plasma is preferred in neonates due to their

high haematocrit levels. The neonates tolerated rapid administration of plasma without ill effects. The following simple

VOL. 45, ~

example illustrates the fluid r e p l a e e ~ a mildly dehydrated and shocked weighing 3 kg with an estimated fluid

of 150 ml. The repair solutions u s e d , ~ biochemicalparameters are not avai l~ are a) Serum at the rate of 25ml/kg i.e, ,~ ml and b) Hartman's solution 25ml/kg

75ml. This makes up for the loss of 1 ~ The body is then kept on mainteaaq solutions. The deficit must be repal~ within 4 hours' time. When the biocherai~ parameters are available, the lack ~f electrolytes is calculated according to

Table 3. Fluids used routinel.7 in pediatric surgical service.

Type of fluid used Contents

m

Isotomic saline Na 156 CI 156 meq/L

�89 isotomic saline with 2~ per cent dextrose

~th isotomic saline with 5 per cent dextrose

Saline lactate

5 per cent dextrose with 40 meq/L Na, K, CI and lactate

5 per cent dextrose with 20 meq Na, K, C! each and lactate

Plasma

Blood

Salt free albumin

5 or 10% dextrose solution

Na 80 CI 80 meq/L

Na 40 C! 40 meq/L

Na 150, CI 100 Lactate 50 meq/L

(40 strength electrolyte solution)

Standard maintenance solution

Serum proteins

Used in prematures

- y A D A V ~ PI.UID AND ELECTROLYT I~ TI tRRAPY IN SURGICAL NRONATES

T a b l e 4 . Estimation of electrotytLs when biochemical parameters are available.

Electrolytes Formula used

Na-t- Cl+ HC08

(E-O) • E C F ~ m e q required 1 litre.

Body wt in neonate) (ECF ~ 2

K + ( E - O ) • I C F Body wt in neonate)

( ICF = - 2

187

�9 ~.CF--Extracellular fluid space in litres ICF-Intra cellular ,, ,, ,, .. E - Expected serum valve in meq

�9 ' 0 - - obse rved . . , , , , , ,

formula given in Tab le 4 and the deficit

fluid is replaced with addit ioanl Tab le 4 deficit electrolytes. This is done either by

adding the electrolytes or using the special

fluid ment ioned in Tab le 3. As a premature neonate has a greater tendency to become hypoglycaemic, repeated blood sugar

~stimation is done and when necessary 10% dextrose is administered, especially

when the drip has been kept going for a

tong time.

(c) Fluid and electrolyte therapy in infants during and after surgical procedures.

During anaesthesia the loss of fluid

occurs via the respiratory tract due to

venti lat ion with dry gases, from the

peritoneal surface and also as the result of shift into the gastrointest inal tract during

the manipu la t ion of the i n t r a . abdomina l viscera. Rep lacemen t is done during the

procedure with 1/4th normal saline in 5%

dextrose solution adminis tered at the rate

of 6 - -8ml / kg / body weight/per hour. The blood loss is replaced, millilitre by millilitre

with donor blood. I f blood is not available, the replacement is carried out temporari ly

with normal saline (1 to 2ml of normal saline for I ml of donor blood) but for a very short durat ion during this procedure.

Postoperative fluid replacement of surgical neonates is highly individualised.

In the South Australian Children's Hospital the regime was to give fluid 20ml/kg less than the maintenance amount for the first

24 hours. This was done with paediatr ic

saline. Meticulous at tent ion is paid to the fluid loss via gastric aspiration and urinary output. In the next twenty-four

hours the haematocr i t and serum electrolytes

values were taken. The gastric aspirat ion

loss is replaced by normal saline or

HaD, mann ' s solution whereas the mainte-

nance amount is carried out with the

standard solution. After knowing - the

188 INDIAN JOURNAL OF PBDIATRI VOL. 45, No. 364

biochemical parameters Potassuim is added

accordingly to the solution as KC!. Loss through the intestine.q or diahorrea is

replaced by half strenght Ringer's lactate solution with more KCI (,mless the biochemical parameters suggest otherwise.) When intravenous fluid is required to be continued over a week or so, the administra- tion of plasma (20--25mllkg) twice a week is given to provide adequate serum proteins.

Here salt poor albumin 2gm/kg/day is also helpful in obtaining a satisfactory level.

Hyponat raemia is a fairly common

entity and this can be corrected with normal taline but in case of extreme tissue trauma, acidosis hyperkalaemia has been teen, and here the monitoring of the electrocarndio-

gram is extremely important. The calonic

fits seen in neonates during the intravenous regime of 4 to 5 days, is usually due to hypomagnaesaemia . This is t reated w i th manesium sulphate solution. Calcium is supplemented with calcium gluconate solution every second or third day when

the drip continues over a period of one week.

Metabol ic acidosis is a common feature with hypothermid neonates and those who come with poor tissue perfusion. This is t reated with 7�89 per cent of sodiun bicarbo- nate solution ( l m l = I meq Na, lmeq HCO3).

The usual practice is to correct half the

deficit at first and the remainder during the following few hours. Here an adequate supply of potassium is important, as a sudden correction can result in alka losit which can precipitate tetany. This can be treated with the intravenous administration of calcium gluconate. Metabolic alkalosh is not so common with neonates unless they have Iong standing duodenal obstruction.

The repair is done with normal saline; potassium is added later when the urinary output becomes adequate (the concentration of KCi, should not be more than 20meg!

litre).

S u m m a r y

Fluid and electrolyte therapy plays a major role in the successful outcome of neonatal surgery. Where hyperalimentation is not available and long term fluid therapy

is required, repeated infusion with plasma, albumin and i0 per cent dextrose has

proved helpful for restoration of serum

proteins and energy.

References

Fink, C W. and Cheek, D.B. (1960). The correcte~ bromide space (extra cellular volume) in the new born. Pediatrics, 26:397.

Darrow, D.G. (1959). The significance of body

size. A.M.,4.J. Dis. Child. 98, .416