Fluids and Electrolytes
September 10, 2008
Karen Koo, PGY5
Chief Critical Care Medicine Fellow
Division of Critical Care Medicine
McMaster University, Hamilton ON
Objectives
Major Body Fluid Compartments
 Review of physiology of volume regulation
 Parenteral Fluid Therapy
 Cases of Electrolyte imbalances

Relationship between the volumes of
major fluid compartments
Composition body fluid compartments
Ion
Plasma
(mmol/L)
ICF
(mmol/L)
Na+
143
9
K+
5
135
Ca2+
1,3
<0,8
Mg2+
0.9
25
Cl-
9
HCO3-
103
24
HPO42-
0,4
74
Sulphate-
0,4
19
Protein-
1,14
64
9
Daily Fluid Requirements

Average Adult needs:
H 2O
~ 30-35ml/kg/hr (2-3 liters/day)
Na+
~1
ml/kg/hr
K+
~1
ml/kg/hr
Cl-
~ 1.5
ml/kg/hr
Sources of daily water loss

Urine
1200-1500 ml/d (30ml/hr)

Sweat
200-400 ml/d

Lungs
500ml/d

Feces
100-200 ml/d
Composition of GI Secretions
Volume
(ml/24h)
Na+*
K+
Cl-
HCO3-
Salivary
1500 (500~2000)
10 (2~10)
26 (20~30)
10 (8~18)
30
Stomach
1500 (100~4000)
60 (9~116)
10 (0~32)
130 (8~154)
0
100~2000
140
5
80
0
Ileum
3000
140 (80~150)
5 (2~8)
104 (43~137)
30
Colon
100-9000
60
30
40
0
Pancreas
100-800
140 (113~185)
5 (3~7)
75 (54~95)
115
Bile
50-800
145 (131~164)
5 (3~12)
100 (89~180)
35
Source
Duodenum
* Average concentration: mmol/L
Daily Electrolyte loss
Na+
100 mEq
K+
100 mEq
Cl-
150 mEq
Quiz #1:
True or False statements
Concerning body fluid compartments:
a) Water constitutes 70% of the total body weight
b) Plasma constitutes a quarter of the ECF volume
d) Interstitial fluid volume for a 70 kg man is
approximately 9 litres
e) The ECF/ICF volume ratio is smaller in infants
and children than it is in adults

Regulation of Fluids
Regulation of Fluids

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Renal sympathetic nerves
Renin-angiotensinaldosterone system
Atrial natriuretic peptide
(ANP)
Parenteral Fluid Therapy
Crystalloids




Na+  main osmotically
active particle
useful for volume expansion (mainly
interstitial space)
for maintenance infusion
correction of electrolyte abnormality
Crystalloids

Isotonic crystalloids
- Lactated Ringer’s, 0.9% NaCl
- 25% remain intravascularly

Hypertonic saline solutions
- 3% NaCl

Hypotonic solutions
- D5W, 0.45% NaCl
- < 10% remain intravascularly, inadequate for fluid
resuscitation
Colloid Solutions


Contain high molecular weight
substancesdo not readily migrate across
capillary walls
Preparations
- Albumin: 5%, 25%
- Hydoxyethyl starches
ie pentaspan
- Red cell concentrates
- platelets, plasma
Distribution of Parenteral Fluids
Type of Fluid
ECF=1/3 TBW
ICF=2/3TBW
IVF=1/4ECF
ISF=3/4ECF
1000ml D5W
1000ml 2/3:1/3
1000ml R/L or
0.9%NS
500mL
5%albumin
83
139
250
250
417
750
667
444
0
500
0
0
100mL 25%
albumin
500mL
Pentaspan
500
-400
0
500
0
0
1 unit RBC
450
0
0
Composition of Parenteral Fluids
Solutions
Volumes
ECF
Na+
K+
Ca2+
142
4
4
Mg2+
Cl-
HCO3-
Dextrose
mOsm/L
5
103
27
280-310
3
109
28
273
Lactated
Ringer’s
500
130
0.9%
NaCl
500
154
154
308
0.45%
NaCl
500
77
77
154
D5W
500
D5/0.45%
NaCl
500
77
77
513
513
1026
154
310
3% NaCl
50
406
6%
Hetastarc
h
500
154
5%
Albumin
250
130160
<2.5
130160
330
25%
Albumin
100
130160
<2.5
130160
330
Quiz #2:
70F has small-bowel fistula with output of
1.5L/d. Replacement of daily losses should
be handled using the fluid solution that has
the following composition:
Na
K
Cl
HCO3
a) 130
4
109
28
b) 154
0
154
40
c) 77
0
77
0
e) 513
0
513
0

Quiz #3:

68M admitted with diagnosis of partial SBO
with Hx of Chrons Disease vomits bilious
coloured emesis. His is lethargic.
37C, 88/50 mmHg, HR 110, RR 25, SpO2 99 on 2Lnp
JVP flat, chest clear with normal heart sounds
Abd distended & mild epigastric tenderness
Na 130, Cl 108, K 5.1, Cr 110, BUN 10.2
Hg 100, WBC 9.9, Plts 400, INR 1.5, APTT 30
Quiz #3:

Your staff asks you to see this patient. What is the
most appropriate resusitation fluid:
a) 1 unit of packed RBC
b) 500 ml of Ringers Lactate solution
c) 500ml 5% albumin
d) 500ml Pentaspan
e) 500ml 0.9% normal saline
SAFE Study (NEMJ 2004:350 Safe Investigators)

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RCT: 4% albumin vs normal saline for
intravascular-fluid resuscitation
Primary outcome: 28 day all cause mortality
N = 6997 patients
No significant differences
 726 deaths albumin group vs 729 deaths saline
group
(RR 0.99; 95% CI 0.91 to 1.09; P=0.87
 numbers of days spent in the ICU or in the
hospital
 days of mechanical ventilation
 days of renal-replacement therapy
28% day Kaplan–Meier Estimates Probability
of Survival: normal saline vs 4% albumin
(NEMJ 2004:350 Safe Investigators)
RR of Death among the Patients in the Six
Predefined Subgroups (NEMJ 2004:350 Safe Investigators)
Colloid solutions for fluid resuscitation
(Cochrane Database Syst Rev. 2008)

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Seventy RCTs comparing colloid solutions in
critically ill and surgical patients thought to need
volume replacement,
N = 4375 participants
Albumin versus hydroxyethyl starch pooled RR
1.14 (95% CI 0.91 to 1.43) for mortality
albumin versus dextran (RR= 3.75 95% CI 0.42 to
33.09).
no evidence that one colloid solution is more
effective or safe than any other
Calculation of Maintenance Fluids
For a 24 hr period, use 100/50/20 Rule
100ml/kg for first 10kg
50ml/kg for next 10kg
20ml/kg for every kg over 20

For hourly maintenance rate, use 4/2/1 Rule
4ml/kg for first 10kg
2ml/kg for next 10kg
1ml/kg for every kg over 20

Quiz #4

55M has been admitted for an elective resection
of a pelvic mass. He is NPO for the next 12
hours. He weighs 70kg and has normal renal
function. What is the most appropriate iv
maintenance rate?
a)
0.9% NS at 200ml/hr
0.45% NS/D5W at 100ml/hr
D5W at 100ml/hr
Ringer’s Lactate at 50ml/hr
b)
c)
d)
Clinical Cases:
Electrolyte Imbalances
Case 1
39M POD2 following ventral hernia repair.
 Background: HTN, DM nephropathy
 Meds: Ramipril 10mg daily, morphine prn
 Patient is weak, c/o paraethesia
 Post-op EKG: Sinus bradycardia 40bpm,
peaked T waves, depressed ST with
prolonged PR, wide QRS
 O/E DTR depressed

Case 1
•
•
What is electrolyte disturbance?
 Hyperkalemia
What are the most likely surgical causes?
 RF, Drugs, Acidosis, Tissue injury
blood transfusions
•
What is the acute management strategy?
 Cardioprotection, shifting, elimination
Case 2
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70F one week of constipation and vomitting.
Background: DM, Dilated cardiomyopathy,
Intestinal fistula
Meds: Insulin, Lasix 80mg bid
Patient c/o weakness, nausea/vomitting and
abdominal tenderness
O/E 36.4C 100/60 HR 110, RR12, SpO2 99% r/a
JVP flat, chest clear, normal heart sounds,
Abdominal distension, no bowel sounds
EKG: Sinus tachycardia with occasional PVCs,
diffuse flattening of T waves, U waves
Case 2
•
•
What is electrolyte disturbance?
 Hypokalemia
What are the most likely surgical causes?
 Drugs (diuretics, steroids, Insulin etc), diarrhea,
vomitting, intestinal fistula, NG aspiration, insufficient
supplementation
•
What is the acute management strategy?
 potassium supplementation iv/po
Case 3
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67M unexplained 30lb wt loss over 6months and
hemoptysis presents a GTC seizure
Background: HTN, smoker
Meds: HCTZ 25mg daily
O/E 37C 110/70 HR 88, RR14, SpO2 98%/ra
Lethargic & confused, No focal neuro deficits
JVP 4cmASA, PPP chest clear, normal heart sounds
Abd distended with faint bowel sounds
CXR: speculated LLL nodule
Case 3
•
What is electrolyte disturbance?
 Hyponatremia
•
What are the most likely surgical causes?
 Access clinical fluid status
Case 3 – Hyponatremia Management
What is the acute management strategy?
•
Depends on etiology & chronicity
•
Be careful! Rate of correction should be
<0.5mEq/h, <10mEq/24hr, <18Eq in first
48h
Check lytes frequently during correction
•
•
Use 3% NaCl ONLY if severe hyponatremia (Na+
<115) or if dramatically symptomatic with acute
onset
Case 4
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89F admitted with acute pancreatitis on ward for 2
weeks. Progressive confusion in last few days
with new tremors
Otherwise healthy, no meds. On TPN.
Net fluid balance 24hrs –4L, u/o 200ml/hr
O/E 36C 110/50 HR 110, RR 10, SpO2 98%r/a
stupourous & clinically hypovolemic
++peripheral edema
Case 4
•
What is electrolyte disturbance?
 Hypernatremia
•
What are the most likely surgical causes?
 Inadequate hydration, diabetes insipitus, diuresis,
vomitting/diarrhea, iatrogenic (TPN)
•
What is the acute management strategy?
 Depends on etiology & chronicity
(D5W or 0.45% normal saline)
Case 5
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26F with newly diagnosed primary
hyperparathyroidism is referred for surgical
assessment.
She has had polydipsia, polyuria and constipation
and abdominal discomfort.
O/E 37C, 100/80, HR99, RR 14, SpO2100%
Confused, JVP 1cm ASA weak pulses
ABD unremarkable
EKG: short QT, prolonged PR interval
Case 5
•
What is electrolyte disturbance?
 Hypercalcemia
•
What are the most likely causes?
 Hyperparathyroidism, immobility, Pagets,
Addisons, Neoplasms, xs Vitamin D, A, Sarcoidosis,
Calcium supplementation, thiazides
•
What is the acute management strategy?
 Volume expansion with NS
 +/- lasix, bisphosphonates, calcitonin, steroids
Case 6
45M presents with profound weakness in
setting of chronic diarrhea.
 Background Alcohol Abuse
 P/E is unremarkable
 EKG: Prolonged QTc interval

Case 6
•
What are the possible electrolyte disturbances?
 Hypokalemia, hypomagnesiumia,
hypophosphtemia, hypernatremia
What is the acute management strategy?
 replace with supplemental magnesium
and potassium phosphate
 fluid therapy
Things you don't want to hear
during surgery:
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5. Damn, there go the lights again...
4. "You know, there's big money in kidneys.
Heck, the guy's got two of them."
3. Everybody stand back! I lost my contact lens!
2. This patient has already had some kids, am I
correct?
1. Nurse, did this patient sign the organ donor
card?

The End 