Fluid and Electrolytes

Water Content

• 50 to 60% of body weight

• Higher in neonates and children

• Lower in elderly

• Lower in women

52

21

14

13

39

27

18

16

18

36

24

22

0%

20%

40%

60%

80%

100% Solids

ECW

ICW

Fat

IntracellularInterstitial

Intravascular

2/3 1/3

3/4 1/4

IntracellularInterstitial

Intravascular

2/3 1/3

3/4 1/4

ECF osmolality = ICF osmolality

K, ATPCreatinine PO4phospholipids

Na, ClHCO3

Intravascular

Interstitial

3/4 1/4

Capillary membrane

Plasma proteins

IntracellularInterstitial

Intravascular

2/3 1/3

3/4 1/4

Na

K

Plasma Na 153

IC K 150

Water Loss - Starvation

Intracellular Interstitial

Intravascular

2/3 1/3

3/4 1/4

Water & Electrolyte Loss -- GI

Intracellular

Interstitial Intravascular

2/3 1/3

3/4 1/4

Replacement Fluids 5% Dextrose

IntracellularInterstitial

Intravascular

2/3 1/3

666ml 250ml 84ml

1L of Crystalloid

IntracellularInterstitial

Intravascular

2/3 1/3

750ml 250ml

1L of Colloid

IntracellularInterstitial

Intravascular2/3 1/3

1000ml

1L of Colloid

IntracellularInterstitial

Intravascular2/3 1/3

1000ml

Sepsis / Shock

IntracellularInterstitial

Intravascular

2/3 1/3

3/4 1/4

Na

Daily Water Requirement

Weight Water requirement

0-10 kg 4mL/kg/hr

10-20 kg 40mL/hr +2ml/kg/hr for each kg>10kg

>20kg 60ml/hr +1ml/kg/hr for each kg>20kg

for 60kg man this = 100ml/hr or 2400 ml/24 hrsfor normal people!!

Ca 2+

Mg 2+

K+

Na+

Cl-

PO43-

Organic anion

HCO3-

Protein

0

50

50

100

150

100

150

Cations AnionsEC

FIC

F

Solutions Volumes Na+ K+ Ca2+ Mg2+ Cl- HCO3- Dextrose mOsm/L

ECF 142 4 5 103 27 280-310

Lactated Ringer’s 130 4 3 109 28 273

0.9% NaCl 154 154 308

0.45% NaCl 77 77 154

D5W 50 250

D5/0.45% NaCl 77 77 50 406

3% NaCl 513 513 1026

6% Hetastarch 500 154 154 310

5% Albumin 250,500 130-160 <2.5 130-

160 330

25% Albumin 20,50,100 130-160 <2.5 130-

160 330

Hyponatremia

• Serum sodium concentration to a level below 136 mmol per liter

• hyponatremia can be associated with low,

normal, or high tonicity

Hyponatremia

• Clinically associated with mainly CNS changes

• Headache, nausea, vomiting, muscle cramps, lethargy, restlessness, disorientation, and depressed reflexes

Hyponatremia

• 32-year-old woman has three grand mal seizures two days after an appendectomy

• 3L of 5 % D5W infused during 1st PO day

• Unknown oral fluids

• O/E she is euvolemic, and weighs 46 kg

• S Na is 112 mmol per liter

• S K is 4.1 mmol per liter

• S osmolality is 228 mOsm / Kg of water

• Urine osmolality is 510 mOsm / Kg of water

513 –112

23 + 1

1L of 3% Nacl will inc Na by 16.7 meq

60ml will increase Na by 1 meq

• EBWater 23 litres

Na now 112 x 23If you give 1L of 3% saline

(513 x 1) + (112x 23)

New conc of Na = (513 x 1) + (112x 23)/24

diff of Na = [(513 x 1) + (112x 23)/24] – (112)

Rate of correction:Can we exceed 1.5 mEq/L/hr?

Total Correction:Should we limit it to less than 12mEq/L for the first 24 hrs?

What is the level to which we should correct the sodium?Full correction?Limit to 120-125 mEq/L?

Should we treat all hyponatremia? What if the patient isasymptomatic ?

Outcome in severe symptomatic hyponatremia:Age (extremes do well; infants and elderly)Sex (women fare poorly)Respiratory arrest always worsens outcomeRate of correction is not a major factor as long asthe total correction in 24 hours is limited

Common causes:Euvolemic: SIADH, Psychogenic polydipsia, hypothyroidOverloaded: Renal, liver, heart failureDry: Diuretic abuse, GI losses, adrenal hypofunction

Effects of Hyponatremia on the Brain

QuadriplegiaPseudobulbar palsySeizuresComaDeath

Hepatic failureK depletionmalnutrition

Hypernatremia

Na >145 Usually due to dehydration:Water loss: GI losses, sweating, Diabetes InsipidusInadequate intake: Access to water impaired

Excessive salt intake is an unusual cause

Correct with NS if patient is hypotensiveUse hypotonic solutions otherwise

Hypernatremia

Hypernatremia

My Surgery Is Postponed!

You had admitted a 67 year old diabetic with end-stagerenal disease, who has been undergoing thrice-weekly dialysis, for the placement of a new A-V fistula. The case has to be postponed by a day because of another emergency.The next morning, as you arrive to see your patient a panicky nurse informs you that he is hypotensive (BP 80/sys.) and has a heart rate of 38/min. A “sharp”medical intern had administered atropine without successfully improving the blood pressure or heart rate.What

investigation / laboratory testmonitoring device

would you request emergently?

Treatment of this patient should be based on all of thefollowing EXCEPT:

a. There should be no delay in treatment, waiting for the electrolyte imbalance to be confirmed by the labb. Administration of intravenous calcium (chloride or gluconate) is the first stepc. Sodium bicarbonate is neededd. Parenteral administration of an ion exchange resin (kayexelate) is needed e. Glucose / insulin will help

Hyperkalemia:Common Causes:

Renal Failure, AcidosisDrugs: K-sparing diuretics, ACE inhibitorsCell death: burns, rhabdomyolysis

Pseudohyperkalemia is an in-vitro rise in K associated with WBC > 100K/mm3 or platelets > 600K/mm3

Haemolysis should also be considered

ECG changes:Peaked T, wide PR&QRS, bradycardia, heart block

Hyperkalemia:

Post Op Ileus

A 47 year old with a history of bronchial asthma has undergone an open cholecystectomy. His postoperative recovery has been complicated by respiratory distressdue to exacerbation of asthma. He is already on peri-opampicillin, gentamicin and metronidazole. Since hisasthma did not respond to 2-hourly nebulized salbutamolhe has been given parenteral steroids. With poor mobilization of secretions he has developed atelectasis of the R lung base and moderate hypoxia. A physician had advised the administration of lasix to help improve PO2 Even though it is now the third post-op day, the patient hasan ileus with RT returns of nearly 1200 ml / day.

Electrolyte Concentration in Body Fluids

Na K Cl HCO3

Saliva Low Moderate Low ModerateBile High Low Moderate ModerateStomach Moderate Variable Low NoneSmall gut High Low Low HighDiarrhea Low High Low ModerateSweat Moderate Low Moderate None

Na and K

• Daily requirements

– Na 1 to 2 mEq / Kg / day– K 1 mEq / Kg / day

Seizures Followed by Unresponsiveness

A52-year-old woman had undergone a mastectomy andaxillary node dissection about 11 years ago. She was nodepositive and received combination chemotherapy. Shehad otherwise been well till 2-3 days prior to admission, whenhas been complaining of nausea, vomiting and anorexia. She was noted to be irritable and then increasingly somnolent. She was brought to your hospital after she had a single generalized convulsion after which she has not awoken. The family also notes that she has been voiding large quantities of urine and has been bedwetting in the last two days. A contrast CT scan of the brain shows no abnormality.

Which of the following would be logical explanationsfor the patient’s symptoms (arrange in decreasing order of likelihood):A. Despite a negative CT scan, brain mets. and associated diabetes insipidus should be considered. Hypernatremia may be the cause of symptoms.B. Mets. to other sites producing ectopic ADH may be causing hyponatremia and an associated encephalopathyC. Since metastaic breast cancer is a common cause of hypercalcemia, we must consider this as the most likely etiology.

What laboratory investigations would you ask for?

“Routine” laboratory values are received:

Na = 152 mEq/LBUN = 50 mg/dlCr. = 2.0 mg/dlBP = 90/50 mm HgHR = 130 frequent PVC's

Ca = 16 mg/dl

Immediate management should include:

a. Disodium etidronate (biphosphonate) to lower Ca levelsb. Immediate hydration with NS; followed by 1/2NS to provide 4-6litres/day + lasix or ethacrynic acidc. Immediate hydration with 5%dextrose followed by fluid to correct 1/2 the estimated free water deficit based on S. Nad. Immediate dialysis with Ca free dialysatee. Calcitonin + steroids

HypercalcemiaCauses:

Malignancy Lung 35%Breast 25%Hematological 14%Head & Neck 6%Renal 3%

Hyperparathyroid Solitary adenoma 80%Hyperplasia 15%Malignancy <5%

Sarcoid and granulomatous diseaseVitamin A&D intoxication

90%ofall

HypercalcemiaSigns & symptoms:

Mental: Stupor, obtundation, apathy, lethargy, confusion, comaNeurological: Reduced muscle tone, reflexesGI& Renal: Nausea, vomiting, constipation, polyuria, polydypsiaECG: Short QT, arrhythmia

Case 4:

In this case which of the following maneuvers will helpresolution of the ileus:a. D/C ampicillinb. D/C gentamicinc. D/C flagyld. Avoid inhaled salbutamole. Switch to parenteral salbutamolf. Change parenteral to inhaled steroidsg. Administer iv calcium gluconateh. Administer iv magnesium sulphate i. D/C lasix j. D/C Ryle’s tubeh. Improve the asthma What is

the defi

nitive t

reatm

ent?

Hypokalemia

Case 5:

A 78 year old male with no known medical illness had presented with septic shock due to a large bowel perforation,which has been treated with a colostomy and antibiotic Rx.He has needed ventilatory and haemodynamic supportbut has stabilized. His weaning off the ventilator is compromised by inadequate patient effort. He is receiving enteral feeding and is tolerating about 100cc/hr (1800 Kcal/day). The only abnormal laboratory values are:

S. Calcium (total) 6.2mg/dl, S. Albumin 2.0 g/dl,

Case 5:

In this case, it would be absolutely imperative to:a. Administer albumin to improve nutritional parameters and enhance weaning from the ventilator b. Administer 10 ml (1 amp) of calcium gluconate (~90 mg) at once and follow-up with an infusion of 0.3-2 mg/kg/hrc. Use calcium “chloride” instead of “gluconate” because its actions are more rapid in onset.d. Provide no treatment, though there is severe hypocalcemia, as the patient is otherwise asymptomatice. Provide no specific treatment, as the clinical and lab parameters are not of concern in the short run

Case 6:

A45 year-old has undergone repeat surgery for the Rxof hyperparathyroidism. His prior surgery over a year agodid not provide symptomatic or biochemical improvement.There is no available documentation of the procedure performed and amount of parathyroid tissue removed. By theevening of the surgery the patient develops hyperreflexia,carpopedal spasm and paresthesias. After initial treatmentwith injectable calcium preparations he is placed on oraldoses of nearly 2.5 g of elemental calcium / day. About 10 days from the surgery he has persistent hyperreflexia and has an ionized Ca of 1.0 mmol/L and PO4 is 5.9 mg/dl

Case 6:

Further treatment should include:

a. Lower the phosphate levels by antacids or sucralfate b. Evaluation for and correction of magnesium deficitsc. Increase the oral calcium supplementsd. Addition of vitamin D supplements

Causes of HypocalcemiaChronic renal failure

Hypoparathyroidism

Acute Pancreatitis

Sepsis

Burns, rhabdomyolysis

Hypomagnesemia

Massive transfusion