The resident's electronic handbook ...

ELECTROLYTES / FLUID BALANCE

• Calcium
• Diabetes insipidus
• Potassium (Kalium )
• Magnesium
• Sodium (Natrium )
• SIADH
• TUR -Syndrome
• Fluid Balances (Wasserhaushalt )
• Perioperative Fluid Therapy

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Calcium

• Hypercalcaemia
• Hypocalcaemia

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Hypercalcaemia

Causes :

• Excessive parathyroid hormone production
• Primary hyperparathyroidism. : Adenoma, Hyperplasia, Adenoma
• Secondary : Renal insufficiency, Acute tubulus necrosis from rhabdomyolysis
• Excessive Calcium or Vitamin D supply
• Milk-alkali syndrome (Burnett's)
• Osteopathy
• Bone metastasis (Breast, Bronchial Tube, Stomach, Kidneys, Uterus)
• Paget's disease
• Osteoporosis
• Others :

Vit.-D-like steroid, Prostaglandins, high Osteoclast activity (paraneopl.) in bronchial-Ca or Hypernephroma, Immobility, Sarcoidosis, Thyreotoxicosis, Addison's disease, Thiazide, Lithium, Thyroid Calcium.

Clinic :

• shortened response time and shortened transfusion
• Symptomatic from 3.5 mmol/l total Ca (Attention: only ionized Calcium meaningful!)
• Muscle weakness, Atrophy, Hyperreflexia, Drowsiness
• Mental changes, Psychosis to Coma
• Nausea, Vomiting, Constipation, Stomach ulcer
• Polyuria, Polydipsia (excessive thirst)
• Itching/Pruritus
• ECG Changes: Prolonged QT Interval

Laboratory : Determine ionized Ca

• Serum-phosphate level low due to hyperparathyroidism
• Alkaline phosphatase (kidney function)

Therapy : a. Monitoring : ECG, SaO2, Laboratory

1. Rehydratation with NaCl, possibly mixed with ZVD
2. Furosemide (Lasix) 20 - 40 mg every 2 - 4 h (Observe Potassium, Magnesium)
3. Ostac 5 mg/kg iv in 500 ml NaCl given over 2 hours, once / 24 hours
4. Calcitonin 3-4 IU/kg iv and 4 IU/kg SQ 12-24 hourly
5. Steroids (Prednisolone 10 - 25 mg/d) for TU, Vit.-D overdose and Sarcoidosis
6. Dialysis
7. Parathyreoidectomy
8. Others : Potentiates vaso-active effect
9. Do not use Thiazide diuretic, do not use absorbable antacid

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Hypocalcaemia

Causes : Frequently as a result of

• Renal Insufficiency, Sepsis, Burns, Shock
• Hypoparathyroidism (post-OP, Radiation)
• Vit.-D deficiency
• Excessive calcium deficiency (a sudden high phosphate level, e.g. after rhabdomyolysis, very acute pancreatitis necrosis (Fitz's), massive transfusion)
• Hyperventilation (rel. deficiency following alkalosis)

Clinic :

• increased neuromuscular susceptibility
• perioral and peripheral paraesthesias, carpopedal spasms, muscle cramps, stridor,
• positive Chvostek's and Trousseau's signs

Laboratory : if total Calcium low,

• determine ionized Calcium, Potassium, Magnesium, Phosphate, Albumin

Therapy : possible use rebreathing for Hyperventilation

ECG Changes:

prolonged QT-interval (including also if hypocaliaemia, myocarditis, hypothyroidism, CNS pathology)

Arrhythmias

5 - 7 mg/kg CaCl2 10% ( Calcium level in adults increases 0.1 - 0.2 mmol/l)

Magnesium level low (see: Magnesium)

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Diabetes insipidus

Symptoms: Thirst, dry mucous membrane, urine production > 500 ml/h

Urine: Specific Gravity < 1005, Urine osmolarity < Plasma osmolarity

Plasma: Osmolarity > 290 mOsm/l

Therapy: Desmopressin (Minirin®) 
         parenteral : 1 - 4 yg iv/im 1-2 x daily (depending on effect)
         nasal : 10 - 40 yg intranasal 1-2 x daily

Differential diagnosis of polyuria during anaesthesia :
         - osmotic diuresis (diabetes mellitus, urea, mannitol)
         - hypervolaemia
         - diabetes insipidus
         - hypercalcaemia (see also under Calcium: Hypercalcaemia) 

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Potassium

• Hyperkalaemia
• Hypokalaemia

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Hyperkalaemia

K > 6.0 ; ECG-Changes + Complications (Anuria)

Etiology:

• Kidney Failure, Massive Blood Transfusion, Burns, Diabetic Keto-acidosis, Depolarized Muscle Relaxants

Symptoms:

• Hyperreflexia, Dysrhythmia, high peaked T-waves

Therapy:

• 200 ml 20% Glucose with 20 E Actrapid in 20 Min. iv
• Correct acidosis
• Increase diuresis,
• Consider giving CaCl2 10 ml (1 g) iv
• Consider starting dialysis
• Potassium-free infusions
• Ion exchanger (Resonium)

ECG-Changes:

• Tent-shaped, high peaked T-waves
• QRS widens
• Wide, flat P wave (loss of P wave)
• Extreme : Blocks form in QRS-Complex
• Negative T-waves

             Treatment                  Begin          Duration     
CaCl2                                                            
10 - 30 ml (1-3g) iv                  immediately      30 - 60 min   
Attention : Digitalis 

NaBic                                   15 min         2 - 3 hours     
30 - 50 mVal (=0.3 x BE x kg)                                     
Glucose-Insulin Infusion              30 - 60 min      Hours       
200 ml Glc20% + 20 IE Actrapid                                   
(central)                                                        
over ca. 20 minutes                                              

Resonium A (Na) or Ca-Resonium        Hours                      
+ 50 g Sorbit in 100 ml Water      (rectal quicker) 
po/rectal                     

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Hypokalemia

K < 3.5 mmol/l

Symptoms:

• Tremor, Cramps, Unrest (Agitation), Tachyarrhythmia

Therapy:

• max. 20 mval K per Hour centrally infused (2 - 3 mmol K/kg/day; max. +40 mmol K ad 1 l Infusion)

K-Deficit :

• (Ksoll - Kist) x 0.4 kgKG = x mmol K

ECG-Changes:

• Flattened T-waves
• U-Waves (after T-waves)
• Extreme : Distinct ST segment depression

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Magnesium

• Hypermagnesemia (Hypermagnesiaemie)
• Hypomagnesemia (Hypomagnesiaemie)

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Hypermagnesemia

see Magnesium Therapy

Hypomagnesemia

Symptoms:

• Weakness, Ileus, Depression, ventr. Tachycardia (type Torsade des Pointes)

Therapy:

• Initially, iv bolus of 10 mmol over 5 Minutes
• Later 10 - 30 mmol/day

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Sodium

• Hyponatremia (Hyponatriaemie)

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Hyponatremia

Categories needing correction :

Etiology:

• Water intoxication (95% in Anaesthesia and Intensive medicine)
• SIADH

General :

• Correct only if Na < 120 mmol/l and in presence of neurological symptoms
• Determine plasma osmolality and rule out isotone/hypertone Hyponatremia

Symptoms:

• Headache, Unwellness, Unrest (Agitation),
• Disorientation, Coma, Cramps

Therapy:

• 50 - 70 mmol/Hour (= 100 - 150 ml 3% NaCl, s.o.)
• Na-Concentration should not be higher than 130 mmol/l
• Correct slowly because of possible centrally forming Myelinolysis
• (Increase ca. 2 mmol/l/h)
• Do not use sodium administration to correct Hyponatremia with normal Osmolarity !

Na-Deficit (in extracellular space) :(Nasoll - Naist) x 0.2 kgKG = x mmol Na

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SIADH

= Syndrome of inappropriate antidiuretic hormone (ADH) secretion

Etiology: craniotomy, SHT, paraneoplasia, e.g. small-celled bronchial carcinoma, Tegretol-NW

Symptoms: Laboratory: Hyponatremia (< 130 mmol/l), Serum Hypoosmolarity (< 280 mosm/l), Osmolarity in Urine > Serum, (Uosmol > 100 mosmol/l, Specific Gravity > 1020)

Clinical: Apathy, Head Ache, Nausea, Epilepsy, Change in Consciousness, Coma

Therapy: For primary disease + Furosemide (Lasix) + Fluid restriction

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TUR - Syndrome

Etiology: Infiltration during TUR-P, Time factor important, Resection < 60 Min.!

Symptoms: Blood pressure increases , Bradycardia, Anaemia, Headache, Vomiting, Convulsions, QRS-wave widening, ST increases when Na ca. 102 mmol/l.

Therapy: Break off Op, bring patient to IMC for observation

• Na < 120: - restrict fluids

- 100 - 150 ml/h 3 % NaCl iv

(1000 ml NaCl 0.9% with 7 Amp. NaCl 29% provides 500 mmol Na/l),

- Lasix 20-40 mg iv

• Na 120-135: restrict fluids, NaCl 0.9 % iv, Lasix

Goal: Na 2-3 mmol/l/h

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Perioperative Fluid Management

Types of Fluid

• Crystalloid Solutions (Ringer's Lactate (RL), NaCl 0.9%, Glucose 5%, Aequifusine)
• Colloid Solutions (Dextran 70, Dextran 40, HAES)
• Ec and blood components

Preoperative Deficit

• 4 - 2 - 1 Rule
• Replace : 50% in the first hour
• 25% in the second hour
• 25% in the third hour

Intraoperative Requirements

• Maintain 4 - 2 - 1 Rule
• Loss: from open abdomen or thorax 5 - 15 ml/kg/h
• Blood 1 : 3 (RL) replace
• Diuresis 1 : 1 replace

Blood Loss

Max.permissible blood loss :

• Lossmax. = Blood volume x (Hktist - Hktmin.) / Hktmean
• (Hktmean = Hktist + Hktmin / 2)
• 1 : 3 with RL replace until max. permissible blood loss, above that then :
• per liter BV, 2 - 3 Ec Concentration and 500 ml replacement solution

Other formulas :

• 3 ml Ec Conc/kg KG: Plasma Hb increase 1 g%
• n ml/kg KG Ec Conc. = Hct increase n %
• 1Ec Conc.= 2-3 % Hct increase
• Calculated Ec-quantity :
• Ec ml = Blood vol. x % Hct-increase / EC-Hct (60 - 70%)

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1996 kaufmannm@ubaclu.unibas.ch