Transcript Fluid and Electrolyte Balance during Injury

Fluid and Electrolyte Balance during
Injury
Zohair Al Aseri. MD. FCEM(UK).FRCPC (EM&CCM)
Chairman ,National Emergency Medicine Committee
Coordinatoor MPH-DME Master
Consultant, ICU Department of Critical Care
Chairman, Department of Emergency Medicine
College of Medicine, King Saud University Medical City.
Riyadh, KSA.
[email protected]
http://fac.ksu.edu.sa/zalaseri
Fluid and Electrolyte Balance during
Injury
Objectives
 Understand normal regulation of fluid balance
 Fluid Imbalance In Shock State
 Fluid Therapy (Types) & Indication
 Electrolyte disturbances in trauma and surgery
 Acid base in surgery patients
Case 1
39 year old male involved in MVC brought to
ED by EMT, he is unconscious, heart rate
120 beat per minute blood pressure of
80/50, intubated in the scene, what is your
immediate action
a) Take further history
b) Start him on dextrose 5% with NS
c) Start him in colloid
d) Start him in Normal saline
Case2
A recovery nurse calling you to see a 70 year
old male, 7 hours post appendicictomy,
because he is drowsy and unresponsive, his
vital signs are normal and oxygen saturation
92% on room air? What is the most likely
diagnosis?
a) Intracranial bleeding
b) Stroke
c) Acute renal failure
d) Respiratory failure
Case3
70 year old male, admitted for elective hernia
repair, kept NPO and started in D5 ½ normal
saline 24 hour ago, his current electrolyte
showed k of 5 mmol and Na of 128 mmol
What is the most likely diagnosis?
a) DI
b) SAIDH
c) Acute renal failure
d) Iatrogenic hyponatremia
Fluid and Electrolyte Balance during
Injury
Hypovolaemia
 Reduced circulating volume
Causes
 Loss of blood, electrolyte-containing fluid or water.
 Third-space loss due
to increased vascular
permeability.
 Hypovoluemia will reduce
nutrient delivery
oxygen
Leads to
 increase healing and recovery times.
and
Fluid and Electrolyte Balance during
Injury
Fluid-conserving measures
Oliguria and sodium and water retention
 Due to the release ADH and aldosterone
after major surgery or injury
 May persist even after normal circulating
volume has been restored.
Fluid and Electrolyte Balance during
Injury
Fluid-conserving measures:
Increased ADH Secretion from the posterior pituitary is
response to
 Afferent nerve impulses from the site of injury
 Atrial stretch receptors (responding to reduced
volume) & aortic and carotid baroreceptors
(responding to reduced pressure)
 Increased plasma osmolality (principally the result of
an increase in sodium ions) detected by
hypothalamic osmoreceptors.
 Input from higher centres in the brain (responding to
pain, emotion and anxiety).
Fluid and Electrolyte Balance during
Injury
Fluid-conserving measures:
 ADH promotes retention of free water
(without electrolytes) by cells of the distal
renal tubules and collecting ducts.
Fluid and Electrolyte Balance during
Injury
Aldosterone
secretion from the adrenal
cortex is increased by:
 Activation of the renin-angiotensin system.
 Renin is released from afferent arteriolar
cells in the kidney in response to reduced
blood pressure and activation of the renal
sympathetic nerves.
Fluid and Electrolyte Balance during
Injury
Aldosterone
secretion
cortex is increased by:
from
the
adrenal
 Renin converts circulating angiotensinogen
to angiotensin AT-1.
 AT-1 is converted by angiotsion converting
enzyme (ACE) in plasma and tissues
(particularly the lung) to AT-2 which cause
arteriolar vasoconstriction and aldosterone
secretion
Fluid and Electrolyte Balance during
Injury
Adrenocorticotropic hormone (ACTH)
 Increased by the anterior pituitary in
response to hypovolaemia and hypotension
via afferent nerve impulses from stretch
receptors in the atria, aorta and carotid
arteries.
 lt is also raised by ADH.
 Direct stimulation of the adrenal cortex by
hyponatraemia or hyperkalaemia.
Fluid and Electrolyte Balance during
Injury
Aldosterone
 increases the reabsorption of both sodium
and water by distal renal tubular
+
 simultaneous excretion of hydrogen and
potassium ions into the urine.
Fluid and Electrolyte Balance during
Injury
Duration of increased ADH and aldosterone
secretion following injury?
 Usually lasts 48-72 hours during which time
urine volume is reduced and osmolality
increased.
Fluid and Electrolyte Balance during
Injury
 Urinary sodium excretion decreases
to 10-20 mmol /24hrs (normal 5080mmol /24 hrs)
 Urinary potassium excretion increases
to > 100 mmol/24 hrs (normal 5080mmol /24 hrs).
Fluid and Electrolyte Balance during
Injury
Blood flow-conserving measures:
Hypovolaemia
 Reduces cardiac preload which leads to a fall
in cardiac output.
 Increased sympathetic activity results in a
compensatory increase in cardiac output,
peripheral vasoconstriction and a rise in
blood pressure.
Fluid and Electrolyte Balance during
Injury
FLUID AND ELECTROLYTE BALANCE:
May be altered in the surgical patient for
several reasons:
 ADH and aldosterone secretion as described
above.
 Loss from the GI tract (e.g. bowel
preparation, ileus, stomas, fistulae).
 Reduced oral fluid intake in the perioperative
period
Fluid and Electrolyte Balance during
Injury
FLUID AND ELECTROLYTE BALANCE:
 Insensible




losses
(e.g.
sweating
secondary to fever).
Third space losses.
Surgical drains.
Medications (e.g. diuretics).
Underlying chronic illness (e.g. cardiac
failure, portal hypertension).
Fluid and Electrolyte Balance during
Injury
Normal water and electrolyte balance:
 Water forms about 60% of total
weight in men and 55% in women.
body
 Approximately two-thirds is intracellular, onethird extracellular.
 Extracellular
water is distributed between
the plasma and the interstitial space
Regulation of Fluid Balance
TOTAL BODY FLUID
(40) liters;60%TBW
Plasma volume
(3 liters,5 %)
Red cell volume
(2 liters)
Extracellular
(15 liters,20%)
The intracellular and
extracellular compartments
are separated by
water-permeable
cell membranes.
Intracellular
(25 liters,40%)
Blood volume (5 liters)
Fluid & Electrolyte Balance
IC. WATER
ECF
2/3 intrest.
1/3 blood
25
Na
140
150
K
4.5
15
Mg
1.2
0.01
Ca
2.4
2
Cl
100
6
Hco3
25
50
Phos
1.2
Regulation of Fluid Balance
ECC Osmolarity
ECF Volume
Maintain BP
Prevent swelling or
shrinking of the cells
Fluid and Electrolyte Balance during
Injury
Osmolality of extracellular fluid
 normally 275-295 mOsmol/kg determined
primarily by sodium and chloride ion
concentrations.
Fluid and Electrolyte Balance during
Injury
Normal water and electrolyte balance:
 Plasma oncotic pressure
determined by albumin.
is
primarily
Fluid and Electrolyte Balance during
Injury
Normal water and electrolyte balance:
In adults,
 Normal daily fluid requirement is 30-35ml
/ kg (-2500 ml /day).
In newborn babies and children
 Contain proportionately more water than adults.
 Daily maintenance fluid requirement at birth is
about 75ml/ kg, increasing to 150 ml/ kg during
the first weeks of life.
Fluid and Electrolyte Balance during
Injury
Normal water and electrolyte balance:
 After first month of life, fluid requirements
decrease and the '4/2/1' formula can be
used
to estimate
maintenance fluid
requirements:
 first l0 kg of body weight requires 4ml /kg/h;
 the next 10kg 2ml /kg/ h;
 thereafter
each
kg of body requires
1ml/kg/h.
Fluid and Electrolyte Balance during
Injury
The estimated maintenance fluid requirements
of a 35 kg child would therefore be:
 (10 X 4) + (10 X 2) + (15 X 1) = 75 mljh.150 .
 The daily requirement for both sodium and
potassium in children is about 2-3mmol/kg.
Fluid and Electrolyte Balance during
Injury
Assessing losses in the surgical patient:
Fluid and Electrolyte Balance during
Injury
Assessing losses in the surgical patient:
Normal Daily Losses and requirements for Fluid and
Electrolytes
Volume Na+ (mmol)
K+ (mmol)
(ml)
Urine
2000
80
60
Insensible losses
from skin and
700
respiratory tract
Faeces
300
10
Less water created
300
from metabolism
Total
2700
80
70
Fluid and Electrolyte Balance during
Injury
Source of Fluid Loss in Surgical Patients
Typical
Losses per
24hrs
Insensible
Losses
Urine
Gut
Third spaces
Losses
Factors Modifying Volume
Losses associated with pyrexia,
700-2000ml sweating and use of non-humidified
10002500ml
300-1000ml
0-4000ml
With aldosterone and DH secretion;
With diuretic Therapy
Losses with obstruction, ileus,
fistulae and diarrhea (may
increase substantially)
Losses with greater extent of
surgery and tissue trauma
Fluid and Electrolyte Balance during
Injury
Insensible fluid losses:
Hyperventilation
 increases insensible water loss
 is not usually large unless the normal mechanisms
for humidifying inhaled air (the nasal passages and
upper airways) are compromised.
this occurs in intubated patients or in those receiving
non humidified high-flow oxygen.
 In these situations inspired gases should be
humidified routinely.
Fluid and Electrolyte Balance during
Injury
Insensible fluid losses:
Pyrexia
 200ml/day for each 1°C rise in temperature.
Sweating
 May increase fluid loss by up to 1 litre/hour
 Sweat also contains significant amounts of sodium (2070mmol/l) and potassium (10mmol/l).
Fluid and Electrolyte Balance during
Injury
The effect of surgery:
The stress response
 ADH leads to water retention and a reduction in
urine volume for 2-3days following major surgery.
 Aldosterone conserves both sodium and water,
further contributing to oliguria.
 Urinary
sodium excretion falls while urinary
potassium
excretion increases, predisposing to
hypokalaemia.
Fluid and Electrolyte Balance during
Injury
'Third-space' losses:
 if tissue injury is severe, widespread
and/or prolonged then the loss of water,
electrolytes and colloid particles into the
interstitial space can amount to many
litres and can significantly decrease
circulating blood volume following trauma
and surgery.
Regulation of Fluid Balance
Q=K[(Pc-Pi)-@(Oc-Oi)]
Arteriole
Venule
Pnet =(37-1)+(0-25)=11
37
mm
Hg
17
Mm
Hg
Oncotic P=25
Interstitial
Hydrostatic P=1
Pnet =(17-1)+(0-25)=-9
Fluid and Electrolyte Balance during
Injury
'Third-space' losses:
 Colloid oncotic pressure throughout the lumen of the




capillary is 25mmHg.
The hydrostatic pressure is 1 mmHg in the
interstitium.
Hydrostatic pressure on the arteriolar side of the
capillary falls from 37 mmHg to 17 mmHg on the
venular side.
net outward pressure on the arteriolar side (37 - 1 25 = 11)
net inward pressure (25 -17-1= 9) on the venular
side.
tending to move fluid
out of the capillaries
tending to keep fluid
within the capillaries
Regulation of Fluid
Balance
Oncotic
pressure
THE STARLING
EQUATION
Hydrostatic
pressure
Excess fluid filtered is
collected through the
lymphatic circulation and
returned to the Systemic
circulation
Fluid and Electrolyte Balance during
Injury
Third-space' losses:
Oedema is formed if
1. hydrostatic pressure increases on the
venular side as in heart failure or
2. colloid oncotic pressure falls due to liver
or kidney disease or
3. permeability is increased as in sepsis and
/or injury.
Fluid and Electrolyte Balance during
Injury
Loss from the gastrointestinal tract
 The magnitude and content of fluid losses
depends on the site of loss or lntestinal
obstruction.
 ln general, the higher an obstruction occurs
in the intestine, the greater the fluid loss
The approximate daily volumes (ml) and electrolyte
concentrations (mmol/l) of various gastrointestinal
fluids.
Plasma
Gastric
Secretions
Intestinal Fluid
(Upper)
Bile and
Pancreatic
secretions
Mature ileostomy
Diarrhoea
(Inflammatory)
Mixed Gastric
Aspirate
Volume
2500
Na+
140
50
K+
5
10
Cl100
80
HCO3
25
40
3000
140
10
100
25
1500
140
5
80
60
500
-
50
110
5
40
20
100
25
40
-
120
10
-
-
Fluid and Electrolyte Balance during
Injury
Loss from the gastrointestinal tract
Paralytic ileus.
 Propulsion in the small intestine ceases, has
numerous causes.
 Resolves within 1-2days of the operation.
Fluid and Electrolyte Balance during
Injury
Loss from the gastrointestinal tract:
Intestinal fistula
 associated
with the greatest
electrolyte losses.
fluid and
Fluid and Electrolyte Balance during
Injury
Loss from the gastrointestinal tract:
Diarrhoea.
 Patients may present with diarrhoea or
develop it during the perioperative period.
 Fluid and electrolyte losses may be
considerable.
Fluid and Electrolyte Balance during
Injury
Intravenous fluid administration:
When choosing and administering
intravenous
fluids it is important to
consider:
 what fluid deficiencies are present.
 fluid compartments requiring replacement.
 electrolyte disturbances present .
 which fluid is most appropriate.
Fluid and Electrolyte Balance during
Injury
Types of intravenous fluid:
Dextrose
 After the IV administration of 1000 ml 5% dextrose
solution, about 670ml of water will be added to the
lFC and about 330 ml of water to the EFC, of which
about 70ml will be intravascular.
therefore
 Dextrose solutions are of little value as resuscitation
fluids to expand intravascular volume
Fluid and Electrolyte Balance during
Injury
Crystalloids
 Sodium chloride 0.9%(NS) and Hartmann' s
solution (Ringer) are isotonic solutions
 Sodium chloride NS 0.9 contains 9g of
sodium chloride dissolved in l000ml of
water.
 (Ringer's lactate) has a more composition,
containing lactate, potassium and calcium
addition to sodium and chloride ions.
Fluid and Electrolyte Balance during
Injury
Crystalloids
Both normal saline and Ringer solution
 have an osmolality similar to extracellular
fluid (about 300m0sm/l)
 distribute rapidly to ECF compartment after
venous administration .
Fluid and Electrolyte Balance during
Injury
 One liter of isotonic saline contains 154 meq
of sodium and an equivalent number of
chloride ions.
Fluid and Electrolyte Balance during
Injury
Balanced solutions, such as Ringer's lactate
 closely match the composition of extracellular
fluid
by providing
physiological
concentrations of sodium and lactate in
place of bicarbonate.
 After administration
the
metabolized, resulting
in
generation.
lactate
is
bicarbonate
Fluid and Electrolyte Balance during
Injury
Balanced solutions, such as Ringer's lactate
 Decrease the risk of hyperchloraermia,
which can occur following large volumes of
fluids NS.
Fluid and Electrolyte Balance during
Injury
Hypertonic saline solutions
 Induce a shift of fluid from the IFC to the EFC
 Reducing brain water and increasing intra
vascular
volume and serum sodium
concentration.
Potential indications
 cerebral oedema
 raised intracranial pressure
 hyponatraemic seizures
 'small volume' resuscitation of hypovolaemic shock.
Fluid and Electrolyte Balance during
Injury
Dextrose saline solutions
 Commercially available 5% dextrose with
0.9% normal saline is a hypertonic solution
(twice the osmolarity of plasma) and should
be used with caution.
Fluid and Electrolyte Balance during
Injury
Colloids:
 albumin or be synthetically modified (e.g.
gelatins, hydroxyethyl starches [HES],
dextrans).
 When
administered, colloid
remains
largely within the intravascular space until the
colloid particles are removed
by the
reticuloendothelial system.
Fluid and Electrolyte Balance during
Injury
Colloids:
 The intravascular half-life is usually between
6 and 24 hours and such solutions are
therefore appropriate for fluid resuscitation.
 Electrolyte-containing
solution
throughout the EFC.
 But No Evidence
distributes
Fluid and Electrolyte Balance during
Injury
Colloids:
 Synthetic colloids are more expensive than
crystalloids and have variable side effect
profiles.
Recognized risks
 Coagulopathy
 Reticuloendothelial system dysfunction
 Pruritus and anaphylactic reactions
 Renal failure when used for resuscitation in
patients with septic shock.
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Maintenance fluid requirements
 under
normal
conditions, adult
daily
sodium requirements (80mmol) may be
provided
by the administration of 5001000ml of 0.9% sodium chloride.
 The remaining requirement to maintain fluid
balance (2000-2500ml).., typically provided
as 5% dextrose.
Fluid and Electrolyte Balance during
Injury
Maintenance fluid requirements
 Daily potassium requirements
(60-80mmol) are
usually
met by adding potassium chloride to
maintenance fluids, but the amount added can be
titrated to measured plasma concentrations.
 “potassium should
not be administered at a rate
greater than 10-20 mmol/h except in severe
potassium deficiency.
Fluid and Electrolyte Balance during
Injury
Maintenance fluid requirement:
 The provision of total parenteral nutrition
should also be considered in this situation.
Fluid and Electrolyte Balance during
Injury
Treatment of postoperative hypovolaemia
and/or hypotension:
 Hpovolaemia
is common
in the
postoperative period and may present with
one or more of the following:
 tachycardia,
 pallor, clammy skin,
 collapsed peripheral pulses
 oliguria and / or hypotension.
Fluid and Electrolyte Balance during
Injury
Treatment of postoperative hypovolaemia
and/or hypotension:
 Intravascular volume should
be rapidly
restored with a series of fluid boluses (e.g.
250-500 ml) with the clinical response being
assessed after each bolus.
Crystalloids Versus Colloids
Crystalloids or colloids in fluid therapy??
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Water depletion
 Pure water depletion is common in surgical
practice, and is usually combined with
sodium loss.
 The most frequent causes are inadequate
intake or excessive gastrointestinal losses.
Fluid and Electrolyte Balance during
Injury
Water excess
common in patients who receive large volumes
of intravenous 5% dextrose in the early
postoperative period.
Such patients have an increased extracellular
volume and are commonly hyponatraemic.
Fluid and Electrolyte Balance during
Injury
Water Excess:
 Difficult to detect clinically
 Patients with water excess usually remain
well
 Oedema
may not be evident until the
extracellular volume has increased by more
than 4 litres.
Fluid and Electrolyte Balance during
Injury
Hypernatraemia:
Normal sodium levels are in range 136144mmol/l.
Hypernatraemia (>145mmol) results from either
water or hypotonic fluid loss or sodium gain.
Fluid and Electrolyte Balance during
Injury
Hypernatraemia:
Water loss is commonly caused by
reduced water intake
vomiting, diarrhea
diuresis, burns
sweating and
insensible losses from the respiratory tract
diabetes insipidus.
Typically associated with hypovolaemia
Fluid and Electrolyte Balance during
Injury
Hypernatraemia:
Sodium gain is usually caused by excess
sodium administration in hypertonic
intravenous fluids
Typically associated with hypervolaemia.
Fluid and Electrolyte Balance during
Injury
Hypovolaemic Hypernatraemia
is treated with isotonic crystalloid
followed by the more gradual administration of
water to correct the relative water deficit.
We can use 5%dextrose,1/2 NS or 1/4 NS
Fluid and Electrolyte Balance during
Injury
Cells, particularly brain cells, adapt to a
high sodium concentration in extracellular
fluid, and once this adaptation has
occurred, rapid correction of severe
hypernatraemia can result in a rapid rise
in intracellular volume, cerebral oedema,
seizures and permanent neurological
injury.
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
(Na- < 135mmolfl) can occur with high, low or
normal extracellular volume.
The commonest cause is the administration of
hypotonic intravenous fluids (as intravenous 5%
dextrose) is administered in the postoperative
period (dilutional hyponatraemia).
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
Other causes include diuretic use and (SIADH)
Co-morbidities associated with secondary
hyperaldosteronism, such as cirrhosis and
congestive cardiac failure.
Fluid and Electrolyte Balance during
Injury
Sodium deficit
This can be calculated as follows:
140- measured sodium x 0.2 x weight in kg
where 0.2 refers to the 20% extracellular
space which represents the compartment in
which sodium is the main cation.
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
Treatment depends on correct identification of
the cause:
If ECF volume is normal or increased, the most
likely cause is excessive intravenous water
administration and this will correct
spontaneously if water intake is reduced.
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
Although less common in surgical patients,
SIADH promotes the renal tubular
reabsorption of water independently of sodium
concentration, resulting in inappropriately
concentrated urine (osmolality> 100m0sm / l)
in the face of hypotonic plasma (osmolality<
290m0sm/ l).
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
The urine osmolality helps to distinguish
inappropriate ADH secretion from excessive
water administration.
'Spot‘ measurement of urine sodium will be
high.
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
In patients with decreased ECF volume,
hyponatracmia usually indicates combined
water and sodium deficiency.
This is most frequently the result of
Diuresis
Diarrhea
Adrenal insufficiency
Treatment by 0.9 sodium chloride
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
severe
hyponatraemia (< 120mmol/ l)
associated with confusion, seizures and
coma.
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
Rapid correction of sodium concentration can
precipitate an irreversible demyelinating
condition known as central pontine myelinolysis
Sodium concentration should not increase by
more than 0.5 mmol/h.
Fluid and Electrolyte Balance during
Injury
Hyponatraemia
This can usually be achieved by the cautious
administration of isotonic (0.9%) sodium
chloride, occasionally combined with the use
of a loop diuretic (e.g. furosemide).
Hypertonic saline solutions only for sever
hyponatremia with CNS manifestation like
seizure
Fluid and Electrolyte Balance during
Injury
Potassium
98% of total body potassium (around
3500mmol) is intracellular
serum potassium concentration (normally 3.55 mmol/ l) is a poor indicator of total body
potassium.
Fluid and Electrolyte Balance during
Injury
Potassium
no absolute formula to determine K deficit.
When the serum K is < 2.5mmol/ l about 100200mmol of KCL will be needed in a 70kg
adult.
Serial monitoring of serum K is necessary
prevent overcorrection
to
Fluid and Electrolyte Balance during
Injury
Potassium
Once the serum K comes above
3.0 mmol /1, K supplements can be reduced.
Acidosis reduces
Na+/kATpase activity and
results in a net efflux of potassium from cells
and hyperkalaemia.
Conversely, alkalosis results in an influx of
potassium into cells and hypokalaemia.
Fluid and Electrolyte Balance during
Injury
Hyperkalaemia
This is a potentially
life-threatening
condition.
caused by
exogenous administration of K
release of K from cells (transcellular
shift) as a result of tissue damage or
changes in the Na / K-ATPase function
impaired renal excretion.
Fluid and Electrolyte Balance during
Injury
Hyperkalaemia
Mild hyperkalaemia (K" < 6mmol/l) is often
asymptomatic.
High K cause progressive slowing of electrical
conduction in the heart and the development
of significant cardiac arrhythmias.
So ECG is mandatory in all suspected
hyperkalaemia
Fluid and Electrolyte Balance during
Injury
Hyperkalaemia
ECG Finding
Tall 'tented' T-waves in the precordial leads are
the earliest
flattening (or loss) of the P waves
prolonged PR interval
widening of the QRS
asystole.
Fluid and Electrolyte Balance during
Injury
Hyperkalaemia
Severe hyperkalaemia (K > 7m mmol/l)
requires immediate treatment
Treatment of hyperkalaemia
Fluid and Electrolyte Balance during
Injury
Hypokalaemia
common in surgical patients.
Dietary intake of k is normally 60-80 mmol /
day.
Under normal conditions, the majority of k loss
(> 85%) is via the kidneys
Maintenance of K balance largely depends
on normal renal tubular regulation.
Fluid and Electrolyte Balance during
Injury
Hypokalaemia
K excretion is increased by
Metabolic alkalosis
Diuresis
Increased aldosterone release
Increased losses from the GI tract.
Fluid and Electrolyte Balance during
Injury
Hypokalaemia
Diagnostic features
Muscle weakness
Paralytic ileus
Flattening of T waves
Prominent u waves
Fluid and Electrolyte Balance during
Injury
Hypokalaemia
For every 3 K ions that come out from the
intracellular compartment, one H and two Na
ions are exchanged
causing extracellular
alkalosis and intracellular acidosis.
Fluid and Electrolyte Balance during
Injury
Hypokalaemia
Treatment
Oral or NG potassium replacement in mild
hypokalaemia.
 Severe (K" < 2.5 mmol/1) or symptomatic
hypokalaemia requires IV replacement.
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Calcium
Clinically significant abnormalities in endocrine
surgery.
Fluid and Electrolyte Balance during
Injury
Magnesium
Hypomagnesaemia is common in
restricted oral intake
intravenous fluids for several days
Fluid and Electrolyte Balance during
Injury
Magnesium
It is frequently associated with other electrolyte
abnormalities, notably hypokalaemia,
hypocalcaemia and
hypophosphataemia.
Fluid and Electrolyte Balance during
Injury
Hypomagnesaemia
associated with arrhythmias (most notably
torsades de pointes (polymorphic ventricular
tachycardia) and atrial fibrillation)
Manifestations of are nonspecific
(muscle weakness, muscle cramps, altered
mentation,
tremors,
hyperreflexia
and
generalized seizures).
Fluid and Electrolyte Balance during
Injury
Hypomagnesaemia
When hypokalaemia and
hypomagnesaemia coexist it may be
difficult to correct the former without
correcting the latter.
Fluid and Electrolyte Balance during
Injury
Phosphate
Phosphate is a critical component in many
biochemical processes such as ATP synthesis,
cell signaling and nucleic acid synthesis.
Fluid and Electrolyte Balance during
Injury
Hypophosphataemia
common in surgical patients
Severe (< 0.4 mmol/1) causes
widespread cell dysfunction,
muscle weakness,
impaired myocardial contractility,
reduced cardiac output
altered sensorium.
Fluid and Electrolyte Balance during
Injury
Hypophosphataemia
most commonly occurs in malnourished and/
or alcoholic patients commencing enteral or
parenteral nutrition.
Sepsis is another situation in which marked
hypophosphataemia can be seen
Fluid and Electrolyte Balance during
Injury
Hypophosphataemia
refeeding syndrome
Hypophosphataemia accompanied by fluid
retention and an increase in ECF volume
To avoid it
feeding should be established gradually with
measurement and supplementation of serum
electrolytes (phosphate, magnesium and
potassium).
Fluid and Electrolyte Balance during
Injury
Hypophosphataemia
Treatment
Phosphate can be supplemented orally or by
slow intravenous infusion.
Fluid and Electrolyte Balance during
Injury
Acid-base balance
Acidosis ('acidaemia' if plasma pH< 7.35)
Alkalosis ('alkalaemia' if plasma pH> 7.45).
Both acidosis and alkalosis may be respiratory
or metabolic in origin.
Fluid and Electrolyte Balance during
Injury
Acid-base balance
VBG is good,
ABG is more accurate
coupled with measurement of blood
lactate concentration
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Acid-base balance
Acid-base abnormalities are tackled by the
body by means of
blood buffers
respiratory system
kidneys.
Fluid and Electrolyte Balance during
Injury
Acid-base balance
When the cause is metabolic, respiratory
compensation is the most rapid (minutes)
followed by the buffering systems hours) and
kidneys (days).
Fluid and Electrolyte Balance during
Injury
Acid-base balance
Bicarbonate buffer is the most important in the
blood (65%) followed by the protein buffers
(30%).
Fluid and Electrolyte Balance during
Injury
Acid-base balance
Bicarbonate buffer (buffer is an acid-base
combination where the acid is only partially
dissociated) moves from left to right or vice
versa depending on the addition of or loss of
acid load with an aim to keep the HCO3/ H2CO3
ratio at 20:1.
Fluid and Electrolyte Balance during
Injury
Metabolic acidosis
increase in plasma hydrogen ions in conjunction
with a decrease in bicarbonate concentration.
A rise in plasma hydrogen ion concentratlon
stimulates chemoreceptors in the medulla
resulting in a compensatory respiratory alkalosis
an increase in minute volume and a fall in PaCO2
Fluid and Electrolyte Balance during
Injury
Metabolic acidosis
Causes
Endogenous acid (e.g. lactic acid or ketone
bodies) referred to as 'increased anion
gap acidosis' or
Increased loss of bicarbonate (e.g. intestinal
fistula, hyperchloraemic acidosis) which leads
to 'normal anion gap acidosis'.
Fluid and Electrolyte Balance during
Injury
Metabolic acidosis
Anion gap 12-l5mmol/l.
Na - (Cl + HCO3)
Fluid and Electrolyte Balance during
Injury
Metabolic acidosis
In surgery or trauma lactic
communist cause
acidosis is the
Fluid and Electrolyte Balance during
Injury
Metabolic acidosis
Base deficit is a measure of the amount of
bicarbonate required to correct acidosis and is
calculated as follows:
Base deficit=
normal bicarbonate- measured bicarbonate x0.2 x
weight in kg.
where 0.2 refers to the extracellular compartment.
Fluid and Electrolyte Balance during
Injury
Metabolic acidosis
Treatment is directed towards restoring
circulating blood volume and tissue
perfusion.
Blood gas analysis should be repeated every
4-6 hours to assess the requirement for
further corrections
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Metabolic alkalosis
A decrease in plasma hydrogen ion
concentration and an increase in bicarbonate
concentration.
A rise in PaCO2 occurs as a consequence of
the rise in bicarbonate concentration, resulting
in a compensatory respiratory acidosis.
Fluid and Electrolyte Balance during
Injury
Metabolic alkalosis in surgery
Mainly due to
hypokalaemia and hypochloraemia.
The kidney has an enormous capacity to
generate bicarbonate ions and this is
stimulated by chloride loss.
Fluid and Electrolyte Balance during
Injury
Metabolic alkalosis
Example
Metabolic alkalosis seen following
significant (chloride-rich) losses from the
GI tract when combined with loss of acid from
conditions such as gastric outlet obstruction.
Fluid and Electrolyte Balance during
Injury
Metabolic alkalosis
Treatment
Adequate fluid replacement
Correction of electrolyte disturbances,
notably hypokalaemia and hypochloraemia
Treatment of the primary cause.
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Respiratory acidosis
common postoperative problem
Increased PC02 and plasma bicarbonate
concentrations.
Hypoventilation
Examples
general anaesthesia
excessive opiate administration
Fluid and Electrolyte Balance during
Injury
Respiratory acidosis
Hypoventilation respiratory acidosis require
ventilatory support
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Respiratory alkalosis
Respiratory alkalosis is caused by excessive
excretion of CO2 as a result of hyperventilation.
PCO2 and
decrease.
hydrogen
ion-concentration
Respiratory alkalosis is rarely chronic and
usually does not need specific treatment.
Fluid and Electrolyte Balance during
Injury
Fluid and Electrolyte Balance during
Injury
Mixed patterns of acid-base imbalance
Mixed patterns of acid-base disturbance are
common, particularly in very sick patients.
Case 1
39 year old male involved in MVC brought to
ED by EMT, he is unconscious, hr 120 bp
80/50, intubated in the scene, what is your
immediate action
a) Take further history
b) Start him on dextrose 5% with NS
c) Start him in colloid
d) Start him in Normal saline
Case2
A recovery nurse calling you to see a 70 year
old male, 7 hours post appendicictomy,
because he is drowsy and unresponsive, his
vital signs are normal and oxygen saturation
92% on room air? What is the most likely
diagnosis?
a) Intracranial bleeding
b) Stroke
c) Acute renal failure
d) Respiratory failure
Case3
70 year old male, admitted for elective hernia
repair, kept NPO and started in D5 ½ normal
saline 24 hour ago, his current electrolyte
showed k of 5 mmol and Na of 128 mmol
What is the most likely diagnosis?
a) DI
b) SAIDH
c) Acute renal failure
d) Iatrogenic hyponatremia
Fluid and Electrolyte Balance during
Injury
Summary
 Understand of The Normal Regulation of Fluid Balance
 Fluid Imbalance In Shock State
 Early Hemodynamic Optimization
 Fluid Therapy (Types) & Indication
 Electrolyte disturbances in trauma and surgery
 Acid base in surgery patients
Thank you