FLUIDS AND ELECTROLYTESin surgical patient

Miklosh Bala, MD

Fluid = Drug!!!

Too wet

Too dry

IT’S COMPLICATED!

Please don’t write up fluids on patients you know nothing about

without looking at various parameters (to be explained below)

Fluid PrescribingFluid Prescribing

Left to the most junior member of the team Wide variability in prescribing practices About 26% prescribed > 2L 0.9% saline/day

Fluid therapy is often poorly taught, poorly understood and poorly done

Objectives

• Review physiology controlling fluid/elec balance

• Appreciate differences in surgical patients

• Be able to order fluid regime for surgical patients

Total Body Waterbody wt% Total body

water%

total 60 100

intracellular 40 67

extracellular 20 33

intravas 5 8

interstitial 15 25

Distribution of Body Fluids

• Does total body water,as a percentage of body weight vary with:

– Age?

– Gender?

Distribution of Body Fluids

• A decrease in the percent of body weight that is water is noted with increasing age.

• Men have a slightly higher percentage of body weight as water than women.

• Why?

Total Body Water

• How much volume is Total Body Water in a typical 70-kg man?

Total Body Water

• 70 kg x 1 L/kg x 60% = 42 L

Fluid Compartments

66%

Intracellular Interstitial Intravascular

25% 8%

Extracellular Fluid Volume

• What are 3 clinical conditions where the ratio of interstital/intravascular volume is increased?

Extracellular Fluid Volume

• Congestive heart failure

• Hypoalbuminemia

• Inflammation

Osmotic Activity

• The total osmotic activity in a solution is the sum of the individual osmotic activities of all the solute particles in the solution.

• What is the osmolarity of– 0.9% NaCl?

Osmotic Activity

• 0.9% NaCl = 154 mEq/L Na + 154 mEq/L Cl

• = 154 mOsm/L Na + 154 mOsm/L Cl

• = 308 mOsm/L

• What is normal plasma osmolarity?

Osmolarity

• Normal plasma osmolarity = 280 - 290 mOsm/L

Electrolytes

• What are the primary electrolytes?

– Extracellular

– Intracellular

Electrolytes

• Extracellular– Cation - Sodium– Anion - Chloride

• Intracellular– Cation - Potassium– Anion - Bicarbonate

Maintenance

• Where is water lost normally?

• How much water is lost normally?

• What is the ideal maintenance fluid?

Normal Water ExchangeAvg daily ml Min daily

ml

Sensibleurine 800-1500 300intestinal 0-250 0sweat 0 0

Insensiblelungs/skin 600-900 600-9008-10 mls/kg/D - 10%/ o rise in Temp

Normal Intake of Water

2000mls - 1300 free water

700 bound to food

additional water comes from catabolism

Maintenance

• Diuretics

• Diarrhea

• Fever

• Open wound

• Artificial airway

Fluid and Electrolyte Therapy

Surgical patients have

• Maintenance volume requirements

• On going losses

• Volume excess/deficits

• Maintenance electrolyte requirements

• Electrolyte excess/deficits

Maintenance

• In the nonstressed, fasting state, 150 g/day dextrose provides enough calories to limit proteolysis.

• This protein-sparing effect is not sufficient in the stressed, catabolic patient.

• What are the daily requirements for sodium and potassium?

Maintenance

• 70 kg man average needs

– Sodium 140 meq/day– Potassium 50 meq/day

• What is the ideal maintenance fluid for the nonstressed, fasting, 70 kg man?

MAINTENANCEMAINTENANCE

If you were on a desert If you were on a desert island, would you drink island, would you drink from the sea or a stream?from the sea or a stream?

0.9% saline is not 0.9% saline is not a maintenance fluida maintenance fluid

Maintenance

• D5 + 1/2NS + 20meq/L KCl• 100 mL/hour

• Provides total– 2.4 L water– 120 g dextrose– 185 meq sodium– 48 meq potassium

On Going Losses NG drains fistulae third space losses

Concentration is similar to plasma

Replace with isotonic fluids

Insensible Losses

• An extra 500 mL of fluid a day is required for every degree of fever above 37C.

Resuscitation

• What is “Third Space?”

Third Space

• Fluid compartments that are not freely mobilized by normal homeostatic mechanisms.

GI Losses

Na+ K+ Cl- HCO3-

Stomach

Pancreas

Bile

S. Bowel

L. Bowel

GI Losses

Na+ K+ Cl- HCO3-

Stomach 70 15 100 0

Pancreas

Bile

S. Bowel

L. Bowel

GI Losses

Na+ K+ Cl- HCO3-

Stomach 70 15 100 0

Pancreas 140 10 70 70

Bile

S. Bowel

L. Bowel

GI Losses

Na+ K+ Cl- HCO3-

Stomach 70 15 100 0

Pancreas 140 10 70 70

Bile 140 10 100 40

S. Bowel

L. Bowel

GI Losses

Na+ K+ Cl- HCO3-

Stomach 70 15 100 0

Pancreas 140 10 70 70

Bile 140 10 100 40

S. Bowel 70 10 50 20

L. Bowel

GI Losses

Na+ K+ Cl- HCO3-

Stomach 70 15 100 0

Pancreas 140 10 70 70

Bile 140 10 100 40

S. Bowel 70 10 50 20

L. Bowel 30 10 10 0

Questions to ask before prescribing fluid

Why?What?How much?

Why does he need fluid?

• Maintenance

• Replacement

• Resuscitation

Fluid and Electrolyte Therapy

Goal normal hemodynamic parameters normal electrolyte concentration

Method replace normal maintenance requirements

ongoing lossesdeficits

Fluid and Electrolyte Therapy

The best estimate of the volume required is the patients response

After therapy started observe vital signs Urine output (0.5mls/Kg/hr) Central venous pressure

Normal Capillary Homeostasis

Fluid Compartments in Shock

Intracellular Interstitial Intravascular

PreloadThird-space Edema

Capillary Leak in Shock

Restoration of Intravascular Space

What fluids does he need?

Crystalloids• Advantages

– readily available– cheap– resuscitate intravascular and interstitial space– promote urinary output

• Disadvantages – does not stay intravascular– larger volumes are needed– may result in edema formation

Non-Protein Colloids• Advantages

– readily available– equivalent to protein colloids

• Disadvantages – expensive– dose related coagulopathy– long tissue half-life (starches)– short intravascular dwell time (dextrans)– anaphylaxis (dextrans >> starches)– difficulty with blood cross-matching

Protein Colloids

• Albumins– 5% human serum albumin– 25% human serum albumin

Protein Colloids• Advantages

– remain intravascular longer– less volume required

• Disadvantages– expensive– increasingly more difficult to obtain– do not restore interstitial volume– enter the interstitial space if capillaries leaky– may interfere with coagulation (gelatins )

Blood Products

• Whole blood

• Packed red blood cells (pRBCs)

• Fresh Frozen Plasma (FFP)

Blood Products

• Advantages– provide oxygen carrying capacity AND

volume– correct coagulation abnormalities

• Disadvantages– most expensive resuscitation fluid– short supply– risk of hepatitis, CMV, HIV– type and crossmatching delays use

How much fluids he needs?

Fluids = Drug

Summary

• Remember the three questions

• Doctors should take time and consult senior if unsure

• Patients on IV fluids need regular labs

• Patients should be allowed food and drink as soon as possible

The The rightright amount amount

of the of the right right fluid fluid

at the at the rightright time time

Metabolic Changes and Nutritional Management of

Surgical Patients

Majority of surgical patients:

►well nourished / healthy

►uncomplicated major surgical procedure

►has sufficient fuel reserve

►can withstand brief period of catabolic insult and starvation of 7 days– Postoperatively:►can resume normal oral intake

►supplemental diet is not needed

Surgical Patients that Needs Nutritional Support

► To shorten the postoperative recovery phase and minimize the number of complications:

1. Chronically debilitated from their diseases or malnutrition.

2. Suffered severe trauma, sepsis or surgical complications

Metabolism of Sick Patient

PHASES:1. Catabolic phase immediately following surgery or trauma

characterized w/ hyperglycemia, increase secretion of urinary nitrogen beyond the level of starvation

caused by increase glucagon, glucocorticoid, glucagon, glucocorticoid, catecholamines and decrease insulincatecholamines and decrease insulin

tries to restore circulatory volume and tissue perfusion

Metabolism of Sick PatientPHASES:

2. Early anabolic phase tissue perfusion has been restored, may last for days to months

depending on:

a. severity of disease

b. previous health

c. medical intervention sharp decline in nitrogen excretion nitrogen balance is positive (4g/day) and there is a rapid

and progressive gain in weight and muscular strength

Metabolism of Sick Patient

PHASES:

3. Late anabolic phase: several months after injury

occurs once volume deficit have been restoredslower re-accumulation of CHONre-accumulation of body fat

Nutritional SupportFundamental goal of nutritional support:

1. To meet the energy requirement for metabolic processes

2. To maintain a normal core body temperature

3. For tissue repair

Nutritional Support

Indication of nutritional support:

1. Pre-morbid state

2. Age of the patient

3. Duration of starvation

4. Degree of the insult

5. Likelihood of resuming normal intake within finite period

Route of Administration:

1. ENTERAL ROUTE

2. PARENTERAL ROUTE (TPN)

3. COMBINATION

ENTERAL

► Advantages:1. more physiological (liver not bypassed)

2. lesser cardiac work

3. safer and more efficient

4. better tolerated by the patient

5. more economical

ENTERAL

Route:

1. Naso-enteric tube feeding

2. Gastrostomy tube (blended food)

3. Jejunostomy tube (elemental diet)

Indications:Principal indication is found in seriously ill

patients suffering from Malnutrition, Sepsis, severe surgical or accidental trauma when the use of the Gastrointestinal tract for feeding is not possible.

Can be supplemental in patients with inadequate oral intake

Parenteral Nutrition

As Primary Therapy:– TPN influence the disease process:

1. GIT fistula2. Renal failure (ATN)3. Short Bowel Syndrome4. Acute Burn (severe trauma)5. Hepatic failure6. With normal bowel length but with malabsorption

syndrome due to SPRUE, enzymatic or pancreatic insufficiency, Ulcerative colitis, regional enteritis

7. Anorexia nervosa

Parenteral Nutrition

As Supportive Therapy:– Nutritional support can be achieved but alteration in the

disease process have not been established.

1. New born GIT anomalies (TIF, gastrochisis, omphalocele)

2. Alimentary tract obstruction (achalasia, stricture, carcinoma, pyloric obstruction)

3. Acute radiation enteritis4. Acute chemotherapy toxicity5. Prolonged ileus6. Prolonged respiratory support7. Large wound losses

Parenteral Nutrition

Benefits of Enteral NutritionOver Parenteral Nutrition

• Cost– Tube feeding cost ~ $10-20 per day – TPN costs up to $100 or more per day!

• Maintains integrity of the gut– Tube feeding preserves intestinal function; it is more physiologic– TPN may be associated with gut atrophy

• Less infection– Enteral feeding—very small risk of infection and may

prevent bacterial translocation across the gut wall– TPN—high risk/incidence of infection and sepsis