Post on 23-Dec-2015
DEFINITIONS
Moles or millimoles: number of particles present per unit volume
Equivalents or milliequivalents: number of electric charges per unit volume
Osmoles or milliosmoles: number of osmotically active particles or ions per unit volume
NORMAL DISTRIBUTION OF BODY FLUIDS
Intra-cellular
Extra-cellular
2/3
1/3
Inter-stitial
Intra-vascular
2/3
1/3
Total body water
NORMAL DISTRIBUTION OF BODY FLUIDS
Total body water; constitutes 50 – 85 % of TBW
-55% - 60% weight for a 70 Kg adult
-Females (45 –60%)
-neonates is 80%-85%
1. Intracellular fluid-2/3
2. Extra cellular fluid-1/3
Extra cellular fluid
-Intravascular (plasma) 1/3
-Interstitial-2/3 of extra cellular fluid
Maintenance Fluid balance
Daily maintenance fluid requirement of 70kg man is 2.5-3 L
Fluid sources Exogenous-drunk fluid or ingested 2-3 liters/day Endogenous –from oxidation of food <500 ml/day•Total body water content & requirement of
children is larger than that of adults
DISTURBANCES OF FLUID AND ELECTROLYTES
CLASSIFICATION
- Disturbance in fluid volume
- Disturbance in composition
- Disturbance in acid base balance
DISTURBANCE IN FLUID VOLUME
Volume deficitmost common fluid volume disorder in the
surgical patientthe lost fluid is - water and electrolytes
Causes
• Losses GI fluids- vomiting, gastric tube, diarrhea and enterocutaneous fistulas
• Sequestration burn
• peritonitis, intestinal obstruction
Clinical feature
Depends on severity Moderate (5-10%): sleepiness, orthostatic
hypotensionSevere (more than 15%)-hypotension,
stupor or coma, sunken eye balls, dry oral mucosa and tongue, poor skin turgor and decrease in body temperature
Treatment-ReplacementBlood loss: RL, NS, BloodExtra cellular fluid: RL, NS
-Rate fast until the vital signs are corrected and adequate
urine output 1-2 liter over 30 minutes to one hour
Monitoringgeneral condition & vital signsurine out put - hourlychest –overload- esp in children & elderly
Volume Excess
is generally iatrogenic secondary to ARF ,cirrhosis, or CHF
C/F edema, basilar rales, distended neck veins, murmurs Children, elderly, pts with cardiac or renal problems
are at increased risk Treatment
Stop IV fluids (Fluid restriction)
Diuretics: e.g. Furosemide
Serum Electrolytes
Cations Concentration, mEq/L
Sodium 135 - 145
Potassium 3.5 - 4.5
Calcium 4.0 - 5.5
Magnesium 1.5 - 2.5
AnionsChloride 95 - 105
CO2 24 - 30
Phosphate 2.5 - 4.5
DISTURBANCE IN ELECTROLYTES
Sodium (Na+)
• most abundant cation of ECF
• After trauma & surgery, period of shut down of sodium excretion for up to 48 hrs
• Daily requirement 1 millimol/kgExcretion - kidneys under the control of
aldosterone
Hyponatremia Na < 1301.sodium and water depletion
-small intestinal obstruction
-high intestinal fistula
2. Water intoxication: over-prescribing excess 5% D/W
Clinical feature
-either fluid deficit or overload
Lab: Serum Na, hematocrit drops
Treatment Rl/NS -volume depletion Fluid restriction, sodium sparing diuretics I-fluid excess
Hypernatremia Na+>145
CausesExcessive water loss- burns,sweatingExcess amount of 0.9% saline solution
Clinical feature fluid excess or fluid deficit
Treatment5% D/W can be infused slowly
Potassium (K+)
most abundant intracellular cation98% -intracellular ¾ -in skeletal muscleDaily requirement is 1mmol/kg
Hypokalemia < 3.5
Causes
_ vomiting in GOO or diarrhea
_ Intracellular shift-in alkalosis
_ k+ loss is primarily renal in origin
_ Diuretics (esp. thiazides)
Clinical features
Most - asymptomatic listlessness, slurred speech, muscular
hypotonia, and depressed reflexes Abdominal distention-paralytic ileus
Treatment
Oral -milk, meat extracts, fruit juices, honey, KCl tablets
IV- 40 mmol KCl added to 1 liter of fluid run over 6 -8 hours. Never directly IV
Correct the underlying causeurine out put must be adequate
Hyperkalemia > 5
Can be due to
- ↓ed renal K+ excretion (ARF or CRF)
- Mineralocorticoid deficiency or unresponsiveness
- K+ release from the ICF
severe injury
surgery, acidosis
catabolic state
Clinical features
Nausea, vomiting, intermittent intestinal colic and diarrhea
ECG - high peaked T waves, widened QRS complex and depressed ST segment
heart block and cardiac arrest
Treatment
_ bicarbonate
_ glucose with insulin-10 to 20 units of regular insulin and 25 to 50 g of glucose
_10 ml of 10% calcium gluconate to suppress the myocardial effect
_ Kayexalate
_ Dialysis
_ Avoid exogenous potassium
ACID – BASE BALABCE
Normal PH-7.36-7.44
The control :
• Blood buffer:-bicarbonate and carbonic acid, phosphates ,serum proteins and meth-hemoglobin
• lung:- excretes acid(CO2 )
• Kidney :- excrete both acid and base
Metabolic Alkalosis
Causes
• Loss of acid from the stomach by repeated vomiting or aspiration
• Excessive ingestion of absorbable alkali
• Hypokalemic alkalosis - pyloric stenosis
Clinical Features
• Cheyne-stokes respiration with periods of apnea
• Tetany
TreatmentRepletion of volume –normal salinepotassium (check urine output )
Respiratory Alkalosis
Causes excessive pulmonary ventilation hyperventilation -severe pain
-hyper pyrexia
-high altitude
Clinical Featurespotassium depletion ventricular arrhythmia and fibrillation
Treatmentbreathing into a plastic baginsufflation of carbon dioxide
Metabolic Acidosis
Primary ↓ in serum [HCO3-] & systemic pH
Causes
_Increase in fixed acids
• anaerobic metabolism (shock, infection)
• renal failure
• ketone bodies in diabetes or starvation
_Loss of bases Chronic diarrheahigh intestinal fistula
Clinical Featuresrapid, deep, noisy breathing urine becomes strongly acidic
TreatmentReperfusionSodium bicarbonate
Respiratory Acidosis
alveolar ventilation is ↓ed, with ↑ing Pco2Occur in upper or lower airway obstruction,
CNS depression & neuromuscular defectshypoxia -restless, tachycardiaCorrect the underlying pathologic condition improve alveolar ventilation- Intubation
and mechanical ventilation
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