1. Basic Fluids and Electrolytes
Douglas P. Slakey

2. Most abnormalities are relatively simple, and many iatrogenic
Why ?
Essential for surgeons (and all physicians)
Based upon physiology
Disturbances understood as pathophysiology
To Encourage Thought Not Mechanical Reaction
Most abnormalities are relatively simple, and many iatrogenic

5. It’s All About Balance Gains and Losses
Sensible and Insensible
Typical adult, typical day
Skin 600 ml
Lungs 400 ml
Kidneys 1500 ml
Feces 100 ml
Balance can be dramatically impacted by illness and medical care

6. Fluid Compartments Total Body Water Relatively constant
Depends upon fat content and varies with age
Men 60% (neonate 80%, 70 year old 45%)
Women 50%

7. TOTAL BODY WATER 60% BODY WEIGHT
ECF
1/3
ICF
2/3
H2O
Predominant solute K+
Predominant solute
Na+

8. I Love Salt Water!

9. Electrolytes (mEq/L) Plasma Intracellular Na 140 12 K 4 150Ca Mg Cl
HCO
Protein

10. Fluid Movement Is a continuous process Diffusion Osmosis
Solutes move from high to low concentration
Osmosis
Fluid moves from low to high solute concentration.
Active Transport
Solutes kept in high concentration compartment
Requires ATP

11. 18 2.8 Movement of Water Osmotic activity Plasma (mOsm/L)
Most important factor
Determined by concentration of solutes
Plasma (mOsm/L)
2 X Na + Glc + BUN

12. Third Space Abnormal shifts of fluid into tissues
Not readily exchangeable
Etiologies
Tissue trauma
Burns
Sepsis

13. Fluid Status Blood pressure Check for orthostatic changes
Physical exam
Invasive monitoring
Arterial line
CVP
PA catheter
Foley

14. Case 1 6 month old boy, born full-term
Developed worsening vomiting during the past week
Today he is listless, irritable, not tolerating oral intake
Pulse 145, BP 70/50
Diaper is dry, anterior fontanel depressed

15. Case 1 Labs
149 92 12
2.8 40
0.8 15 45
200
12.3

16. Case 1 F & E Problem List Hypovolemia Hypernatremia Hypokalemia
Alkalosis
149 92 12
2.8 40
0.8

17. Volume Deficit Most common surgical disorder Signs and symptoms
CNS: sleepiness, apathy, reflexes, coma
GI: anorexia, N/V, ileus
CV: orthostatic hypotension, tachycardia with peripheral pulses
Skin: turgor
Metabolic: temperature

18. Dehydration Chronic Volume Depletion Affects all fluid components
Solutes become concentrated
Increased osmolarity
Hct can increase 6-8 pts for 1 L deficit
Patients at risk:
Cannot respond to thirst stimuli
Diabetes insipidus
Treatment: typically low Na fluids

19. Hypovolemia Acute Volume Depletion
Isotonic fluid loss, from extracellular compartment
Determine etiology
Hemorrhage, NG, fistulas, aggressive diuretic therapy
Third space shifting, burns, crush injuries, ascites
Replace with blood/isotonic fluid
Appropriate monitoring
Physical Exam
Foley (u/o > 0.5 ml/kg/min)
Hemodynamic monitoring

20. Treatment – Patient weight is 12 kg
Fluid choice?
Replace volume
Replace Cl
How to order
“Bolus”
Think about rate over time
Adequate access important
What would maintenance fluid choice and rate be?
4-2-1 rule
Why not replace K right away?

21. Acid – Base Balance Acidosis Alkalosis
May result from decreased perfusion i.e. decreased intravascular volume
K will move out of cells
Alkalosis
Complex physiologic response to more chronic volume depletion
i.e. vomiting, NG suction, pyloric stenosis, diuretics
K will move intracellular

22. Paradoxical Aciduria Hypochloremic Hypovolemia Na Na H Cl K
Loop of Henle

23. Case 1 When should we operate?
Need to wait until adequately resuscitated
Why
Monitor by:
Normalized vital signs
Good urine output
Normalized labs

24. Case 2 64 year old, had colon resection 5 days ago
“doing well” ….until….
Suddenly develops atrial fibrillation with rapid ventricular response
P 120, irregular; BP 115/70; RR 20
Temp 38.7
Confused, anxious

25. Case 2 Labs
128
100 12
3.0 22
0.8
Mg 1.1 10 30
180
16.3

26. Case 2 Diagnoses? New onset A fib, why? Hypervolemia Hyponatremia
Hypokalemia
Hypomagnesemia
Anemia

27. Case 2
Why does patient have hypervolemia?

28. Increased Antidiuretic Hormone (ADH)
Causes
Surgical stress (physiologic)
Cancers (pancreas, oat cell)
CNS (trauma, stroke)
Pulmonary (tumors, asthma, COPD)
Medications
Anticonvulsants, antineoplastics, antipsychotics, sedatives (morphine)

29. Hyponatremia – how to classify
Na loss
True loss of Na
Dilutional (water excess)
Inadequate Na intake
Classified by extracellular volume
Hyovolemic (hyponatremia)
Diuretics, renal, NG, burns
Isotonic (hyponatremia)
Liver failure, heart failure, excessive hypotonic IVF
Hypervolemic (hyponatremia)
Glucocorticoid deficiency, hypothyroidism

30. Patient was receiving maintenance Fluids
D5 0.45NS + 20 mEq KCl/L at 125 ml/hr

31. How much Sodium is Enough???NS
0.9% = 9 grams Na per liter
0.45 NS = 4.5 grams per liter
125 ml/hour = 3000 ml in 24 hours
3 liters X 4.5 grams Na = 13.5 GRAMS Na!
(If 0.2 NS: 3 liters X 2 grams Na = 6 grams Na)

32. Case 2 - How to treat A fib: ACLS protocol Correct electrolytes
Replace Mg and K
Decrease volume, fluid restriction

34. Case 3 23 year old with jejunostomy
Had colon and ileum resected due to injury
Tolerates some oral nutrition, but has high output from jejunostomy (2.5 liters per day), therefore requires TPN
P 118, BP 105/60

35. Case 3 Labs
154
114 28
3.2 16
2.4
Glucose 213
Mg 1.4
9.7 28
380
10.3

36. Current Problems Hypovolemia Increased plasma osmolarity Hypernatremia
2 X (213/18) + (28/2.8) = 329.8
Hypernatremia
Renal insufficiency
Acidosis

37. Case 3 - Hypovolemia Fistula output Hyperglycemia
High volumes can rapidly lead to dehydration
Electrolyte composition can be difficult to estimate
Can send aliquot to laboratory
May need to be replaced separately from maintenance (TPN) fluids
Hyperglycemia

38. Relatively too little H2O
Hypernatremia
Relatively too little H2O
Free water loss (burns, fever, fistulas)
Diabetes insipidus (head trauma, surgery, infections, neoplasm)
Dilute urine (Opposite of SIADH)
Osmotic diuresis
Nephrogenic DI
Kidney cannot respond to ADH
Too much Na, usually iatrogenic

39. [0.6 X wt (kg)] X [Serum Na/140 - 1]
Hypernatremia
Free water deficit:
[0.6 X wt (kg)] X [Serum Na/ ]
Example:
Na 154, 60 kg person
(0.6 X 60) X [(154/140) - 1]
X [1.1 -1]
36 X = 3.6 Liters

40. Case 3 – How to Treat Correct hyperglycemia
154
114 28
3.2 16
2.4
Correct hyperglycemia
Replace pre-existing volume deficits
Reduce ostomy output if possible
What to do with:
Acidosis?
Hypokalemia?

42. Case 4 58 year old, had a recent kidney transplant
Laboratory calls with critical value:
Potassium 5.9
What to do?

43. Case 4
Evaluate the patient
Exam
ECG
Order repeat labs

44. Hyperkalemia - Common Causes
Spurious
Blood drawn above running IV
Underlying disease
Renal failure
Rhabdomyolysis
Associated medications
Too much K+, ACE inhibitors, beta-blockers, antibiotics, chemotherapy, NSAIDS, spironolactone

45. Treatment Mild: dietary restriction, assess medications
Moderate: Kayexalate
Do not use sorbitol enema in renal failure patients
Severe: dialysis

46. Potassium and Ph Acidosis Alkalosis Normally 98% intracellular
Extracellular H+ increases, H+ moves intracellular, forcing K+ extracellular
Alkalosis
Intracellular H+ decreases, K+ moves into cells (to keep intracellular fluid neutral)

47. Hyperkalemia - Treatment
Emergency (> 6 mEq/l)
Monitor ECG, VS
Calcium gluconate IV (arrhythmias)
Insulin and glucose IV
Kayexalate, Lasix + IVF, dialysis
Mild to Moderate
Mild: dietary restriction, assess medications
Moderate: Kayexalate
Do not use sorbitol enema in renal failure patients
Severe: dialysis

48. The End
Makani U’i

50. Remember JVD?