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Fluids and Electrolytes for surgeons. Anil S. Paramesh MD, FACS Associate Professor of Surgery and Urology. Why ? . Essential for surgeons (and all physicians) Knowledge can diagnose, treat and prevent many of the problems in surgical patients

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fluids and electrolytes for surgeons

Fluids and Electrolytes for surgeons

Anil S. Paramesh MD, FACS

Associate Professor of Surgery and Urology

slide2
Why ?
  • Essential for surgeons (and all physicians)
  • Knowledge can diagnose, treat and prevent many of the problems in surgical patients

Most abnormalities are relatively simple, and many iatrogenic

fluid compartments
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%
slide4

TOTAL BODY WATER

60% BODY WEIGHT

ECF

1/3

(20% BW)

ICF

2/3 (40% BW)

H2O

Predominant solute

K+

Predominant solute

Na+

75% interstitial

25% intravascular

(5% of BW)

it s all about balance
It’s All About Balance
  • Gains and Losses
    • Most individuals ingest approx 2 – 2.5 L/day
    • 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
how much fluid can a patient lose if a patient could lose fluid
How much fluid can a patient lose if a patient could lose fluid?
  • Sensible losses
    • Blood (most pts can tolerate 500 cc BL)
    • Sweat (up to 4 L /day)
    • Tears – (diarrhea)
  • Insensible losses
    • Skin 250 cc/day/degree fever
    • Trach/vent – upto 1500 cc/day
    • Peritoneum - > 1/day
    • Third spacing
slide8

Electrolytes

(mEq/L) Plasma Intracellular

Na 140 12

K 4 150

Ca 50.0000001

Mg 2 7

Cl 103 3

HCO3 24 10

Protein 16 40

fluid movement
Fluid Movement
  • Is a continuous process
  • Diffusion
    • 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
movement of water
Movement of Water
  • Osmotic activity
    • Normal around 300 mOsm/L
    • Osmolality determined by concentration of solutes

Plasma (mOsm/L)

2 X Na + Glc + BUN

18 2.8

fluid status
Fluid Status
  • Blood pressure
  • Check for orthostatic changes
  • Physical exam
  • Invasive monitoring
    • Arterial line
    • CVP
    • PA catheter
    • Foley
volume deficit
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
hypovolemia acute volume depletion
HypovolemiaAcute Volume Depletion

Determine etiology

Hemorrhage,

NG, fistulas,

Aggressive diuretic therapy

Third space shifting, burns, crush injuries

Ascites

what kind of fluid are we losing
What kind of fluid are we losing?
  • Sweat – hypotonic (low sodium)
  • Insensible loss is pure water
  • GI loss is usually isotonic
    • Stomach – acid, high CL
    • Pancreas/bile – high HCO3
    • Saliva – high K
iv fluids a la carte
IV fluids a la carte
  • NaCl
    • Normal saline (0.9%) has 154 mEq/L Na, 154 mEqCl
    • ½ Normal has 77 mEq Na/Cl
  • Lactated Ringers
    • Has 130 Na, 109 Cl (also has some K, Ca, lactate)
  • D5Water
    • Good replacement for insensible losses
case 1
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
case 1 f e problem list
Case 1 F & E Problem List
  • Hypovolemia
  • Hypochloremia
  • Hypokalemia
  • Alkalosis
treatment patient weight is 12 kg
Treatment – Patient weight is 12 kg
  • Fluid choice?
    • Replace volume
    • Replace K/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
acid base balance
Acid – Base Balance
  • Acidosis
    • May result from decreased perfusion i.e. decreased intravascular volume
    • K will move out of cells (K+ - H+ exchange)
  • Alkalosis
    • Complex physiologic response to more chronic volume depletion
    • i.e. vomiting, NG suction, pyloric stenosis, diuretics
    • K will move intracellular
paradoxical aciduria
Paradoxical Aciduria

Hypochloremic

Hypovolemia

Aldosterone activation

H

Na

Na

K

Loop of Henle

case 1 when should we operate
Case 1 When should we operate?
  • Need to wait until adequately resuscitated
  • Why
  • Monitor by:
    • Normalized vital signs
    • Good urine output
    • Normalized labs
case 2
Case 2
  • 64 year old, 50 kg, 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
case 2 labs
Case 2 Labs

Mg 1.1

180

16.3

case 21
Case 2
  • Diagnoses?
    • New onset A fib, why?
    • Hypervolemia
    • Hyponatremia
    • Hypokalemia
    • Hypomagnesemia
    • Anemia
case 22
Case 2
  • Why does patient have hypervolemia?
increased antidiuretic hormone adh
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)
hyponatremia how to classify
Hyponatremia – how to classify
  • Na loss
    • True loss of Na
    • Dilutional (water excess)
    • Inadequate Na intake
  • Classified by extracellular volume
    • Hypovolemic(hyponatremia)
      • Diuretics, renal, NG, burns
    • Isovolemic(hyponatremia)
      • Liver failure, heart failure, excessive hypotonic IVF
    • Hypervolemic (hyponatremia)
      • Glucocorticoid deficiency, hypothyroidism
case 2 how to treat
Case 2 - How to treat
  • A fib: ACLS protocol
  • Correct electrolytes
    • Replace Mg and K
  • Decrease volume, fluid restriction
case 3
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
case 3 labs
Case 3 Labs

Glucose 213

Mg 1.4

380

10.3

current problems
Current Problems
  • Hypovolemia
  • Increased plasma osmolarity
    • 2 X 154 + (213/18) + (28/1.8) = 335
  • Hypernatremia
  • Renal insufficiency
  • Acidosis
case 3 hypovolemia
Case 3 - Hypovolemia
  • Fistula output
    • 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
hypernatremia
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
hypernatremia1
Hypernatremia

Free water deficit:

[0.6 X wt (kg)] X [Serum Na/140 - 1]

Example:

Na 154, 60 kg person

(0.6 X 60) X [(154/140) - 1]

X [1.1 -1]

36 X 0.1 = 3.6 Liters

case 3 how to treat
Case 3 – How to Treat
  • Correct hyperglycemia
  • Replace pre-existing volume deficits
  • Reduce ostomy output if possible
  • What to do with:
    • Acidosis?
    • Hypokalemia?
case 4
Case 4
  • 58 year old, had a recent kidney transplant
  • Laboratory calls with critical value:
    • Potassium 5.9
  • What to do?
case 41
Case 4
  • Evaluate the patient
    • Exam
    • ECG
    • Order repeat labs
hyperkalemia common causes
Hyperkalemia - Common Causes
  • Hemolyzed specimen
  • Underlying disease
    • Renal failure
    • Rhabdomyolysis
  • Associated medications
    • Too much K+, ACE inhibitors, beta-blockers, antibiotics, chemotherapy, NSAIDS, spironolactone
potassium and ph
Potassium and Ph
    • Normally 98% intracellular
  • Acidosis
    • Extracellular H+ increases, H+ moves intracellular, forcing K+ extracellular
  • Alkalosis
    • Intracellular H+ decreases, K+ moves into cells (to keep intracellular fluid neutral)
hyperkalemia treatment
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
    • Severe: dialysis