sodium bicarbonate below ( 1. 26 %) can be infused over
3 – 4 hours with plasma-pH and electrolyte monitoring. In
severe shock, for example in cardiac arrest, metabolic
acidosis can develop without sodium depletion; in these
circumstances sodium bicarbonate is best given
intravenously as a small volume of hypertonic solution, such
as 8. 4 %; plasma pH and electrolytes should be monitored.
Forchronic acidotic states, sodium bicarbonate can be given
by mouth.
Trometamol (tris(hydroxymethyl)aminomethane, THAM)
p. 583 , an organic buffer, corrects metabolic acidosis by
causing an increase in urinary pH and an osmotic diuresis. It
is indicated when sodium bicarbonate is unsuitable as in
carbon dioxide retention, hypernatraemia, or renal
impairment. It is also used during cardiac bypass surgery
and, very rarely, in cardiac arrest.Plasma and plasma substitutes
Albumin solution p. 595 , prepared from whole blood, contain
soluble proteins and electrolytes but no clotting factors,
blood group antibodies, or plasma cholinesterases; they may
be given without regard to the recipient’s blood group.
Albumin is usually used after the acute phase of illness to
correct a plasma-volume deficit; hypoalbuminaemia itself is
not an appropriate indication. The use of albumin solution
in acute plasma or blood loss may be wasteful; plasma
substitutes are more appropriate. Concentrated albumin
solution may also be used to obtain a diuresis in
hypoalbuminaemic patients (e.g. in nephrotic syndrome).
Recent evidence does not support the previous view that
the use of albumin increases mortality.
Plasma substitutes
Gelatin p. 595 is a macromolecular substance that is
metabolised slowly. Gelatin may be used at the outset to
expand and maintain blood volume in shock arising from
conditions such as burns or septicaemia; it may also be used
as an immediate short-term measure to treat haemorrhage
until blood is available. Gelatin is rarely needed when shock
is due to sodium and water depletion because, in these
circumstances, the shock responds to water and electrolyte
repletion; see also the management of shock.
Plasma substitutes shouldnotbe used to maintain plasma
volume in conditions such as burns or peritonitis where
there is loss of plasma protein, water, and electrolytes over
periods of several days or weeks. In these situations, plasma
or plasma protein fractions containing large amounts of
albumin should be given.
Large volumes ofsomeplasma substitutes can increase the
risk of bleeding through depletion of coagulation factors.Parenteral preparations for fluid and electrolyte
imbalance
Electrolytes and water
Neonates lose water through the skin and nose, particularly
if preterm or if the skin is damaged. The basicfluid
requirement for a term baby in average ambient humidity is
40 – 60 mL/kg/day plus urinary losses. Preterm babies have
very high transepidermal losses particularly in thefirst few
days of life; they may need morefluid replacement than full
term babies and up to 180 mL/kg/day may be required. Local
guidelines forfluid management in the neonatal period
should be consulted.Intravenous sodium
The sodium requirement for most healthy neonates is
3 mmol/kg daily. Preterm neonates, particularly below
30 weeks gestation, may require up to 6 mmol/kg daily.
Hyponatraemiamay be caused by excessive renal loss of
sodium; it may also be dilutional and restriction offluid
intake may be appropriate. Sodium supplementation is likely
to be required if the serum sodium concentration is
significantly reduced.Hypernatraemiamay also occur, most often due to
dehydration (e.g. breast milk insufficiency). Severe
hypernatraemia and hyponatraemia can causefits and rarely
brain damage. Sodium in drug preparations, delivered via
continuous infusions, or in infusions to maintain the
patency of intravascular or umbilical lines, can result in
significant amounts of sodium being delivered, (e.g.
1 mL/hour of 0. 9 % sodium chloride infused over 24 hours is
equivalent to 3. 6 mmol/day of sodium).BICARBONATE
Sodium bicarbonate
lINDICATIONS AND DOSE
Chronic acidotic states such as uraemic acidosis or renal
tubular acidosis
▶BY MOUTH
▶Neonate:Initially 1 – 2 mmol/kg daily in divided doses,
adjusted according to response.▶Child:Initially 1 – 2 mmol/kg daily in divided doses,
adjusted according to response
Severe metabolic acidosis
▶BY SLOW INTRAVENOUS INJECTION, OR BY INTRAVENOUS
INFUSION
▶Child:Administer an amount appropriate to the body
base deficit, to be given by slow intravenous injection
of a strong solution (up to 8. 4 %), or by continuous
intravenous infusion of a weaker solution (usually
1. 26 %)
Renal hyperkalaemia
▶BY SLOW INTRAVENOUS INJECTION
▶Neonate: 1 mmol/kg daily.▶Child: 1 mmol/kg daily
Persistent cyanotic spell in a child with congenital heart
disease despite optimal use of 100 % oxygen and
propranolol
▶BY INTRAVENOUS INFUSION
▶Child: 1 mmol/kg, dose given to correct acidosis (or
dose calculated according to arterial blood gas results),
sodium bicarbonate 4. 2 % intravenous infusion is
appropriate for a child under 1 year and sodium
bicarbonate 8. 4 % intravenous infusion in children over
1 yearlCONTRA-INDICATIONS
▶With oral useSalt restricted diet
lCAUTIONSRespiratory acidosis
lINTERACTIONS→Appendix 1 : sodium bicarbonate
lSIDE-EFFECTS
▶With intravenous useSkin exfoliation.soft tissue necrosis.
ulcer
▶With oral useAbdominal cramps.burping.flatulence.
hypokalaemia.metabolic alkalosis
lMONITORING REQUIREMENTS
▶With intravenous usePlasma-pH and electrolytes should be
monitored.
lDIRECTIONS FOR ADMINISTRATION
▶With intravenous useForperipheral infusiondilute 8. 4 %
solution at least 1 in 10. Forcentral line infusiondilute 1 in
5 with Glucose 5 %or 10 %orSodium Chloride 0. 9 %.
Extravasation can cause severe tissue damage.
▶With oral useSodium bicarbonate may affect the stability or
absorption of other drugs if administered at the same time.
If possible, allow 1 – 2 hours before administering other
drugs orally.586 Fluid and electrolyte imbalances BNFC 2018 – 2019
Blood and nutrition9