Fluid
Physiology:- Body water adult male contain 60 % water adult female contain 55 % water due to more fat. new born baby 75 % water Total body water 40% intracellular 60 % extra cellular which is present in interstitial fluid and plasmaWater Sources In The Body : -
Water input : 1-Exogenous by drinking and from food 2-3 liter per day . 2- Endogenous from oxidation of carbohydrate to water and CO2 ,this metabolic water is about 350 ml / 24 hr. Water out put : - 1-lung 400 ml/ 24 hr during respiration. 2-skin 600-1000 ml / 24 hr sweating. 3-faeces 60-150 ml / day with stool. 4- urine 1500 ml/24 hr Urine out put under multiple factors including blood volume, hormonal [ADH] and nervous factor.Water imbalance:-
water depletion [pure dehydration ] Pure water depletion is rare in surgical practice. Aetiology :- 1- lack of water intake: difficulty or inability to swallow , coma . 2- diabetes insipidus. 3- increased out put in fever and osmotic diuresis. Consequences:- - Decrease in water lead to decrease in volume of all body fluid compartment. -Since solute content dose not change, hyper osmolarity results . - Osmorecepters are stimulated and secretion of ADH is increased , more water is absorbed from the distal tubules .Clinical-features
1- intense thirst and weakness . 2- Reduced tissue turgor. 3- Oliguria with increase specific gravity. Treatment :- Estimation of water loss clinically and by assuming that each 3 m mol elevation of serum sodium concentration above normal represent loss of one liter of body water. - treatment of water loss by sodium free water like I.V 5% glucose.
WATER EXCESS[WATER INTOXICATION]
Aetiology : -water excess often is iatrogenic due to excess administration of water . 1-The commonest cause in surgical practice is over infusion of I.V fluid 5% Dextrose post operatively . 2-Colorectal wash out with water instead of N.S before colonic surgery. 3-During [TURP] transurethral resection of the prostate using water as irrigating fluid Consequences:- Water excess lead to increase in the volume of all fluid compartment. - Solute not altered and state of hypo osmolarity results. - Hypothalamic osmorecepters are inhibited & pituitary secretion of ADH is decreased resulting in increased water renal excretionClinical :-
-Moderate water excess may be asymptomatic :-- 1- Increase urine volume . 2- Increase body weight , no pitting odema . 3- Decrease serum sodium con. & falling haematocrit value - Marked water excess [serum Na+ conc. Below 120 mEq/liter]:- 1- Swelling of brain cell that leads to drowsiness , weakness &ultimately convulsions and coma [water Intoxication]. 2-Nausea and vomiting of clear fluid are common.Treatment-Mild water excess---restriction of water only-Severe cases –induction of diuresis by manitol, careful infusion of small amounts of concentrated 5% NaCl.Electrolytes Metabolism
Na. is the main extra cellular cation. K. is the main intra cellular cation. Normal serum electrolytes: Cations Na+ 124 m mol/liter K+ 4 m mol/liter Anions Cl 103 m mol/liter. HCO3 25 m mol/liter. Under normal conditions the number of anions must equal to the number of cations to keep the electrochemical neutrality of the ECF. The main cation Na+ & K+ measured by laboratory. The main anion HCO3 & Cl measured by lab. Other anion which is not measured like phosphate , sulphates, protein and organic acids [make the difference in the value between anions & cations &this known as the anaion gap] which represent other anion that are not usually measured . Anion gap = (Na+K)-(HCO3+Cl).Na + :-
- main extra cellular cation . Play role in maintaining blood volume . - balance between intake through diet & out put through mainly urine ,some in stool ,negligible in respiration , in profuse sweating loss of considerable amount of Na+. - Daily intake 1 ml mol/kg NaCl , 500 ml of isotonic 0.9 % saline solution . - Sodium balance controlled by kidney ,sweating ,and in is under control of adrenal corticoid [powerful conservator of Na+ being aldosterone]. - Obligatory reduction in sodium excretion follow surgery or trauma for a period of 24 hour due to increase adrenocortical activity , so it is not advisable to give large amount of solutions containing sodium after surgery for about 2 days.
K+ :-
- is the major intra cellular cation . - Abnormalities of K+ concentration are of concern because of the risk of cardiac arrhythmias. - Normal daily intake 1 m mol/kg , k+ rich food fruit, milk, and honey. - k+ mainly excreted through urine equal to intake . - Increase k+ excretion occur following surgery and trauma ,due to tissue damage ,start in the first 24 hr. and last for 3-4 days, usually there is good reserve of k+.Ca+ :-
- Majority of ca+ in bones with phosphate and carbonate. - other present as extra cellular cation in two forms :- 1- Ionized free fraction which responsible for biological effects of Ca+ such as neuromuscular stability , blood coagulation & cellular enzyme processes 2- non ionized protein bind chiefly albumin. - level of plasma protein is essential for proper analysis of the serum Ca., low albumin give false low serum Ca. & vice versa. -The ratio of ionized to non ionized Ca is related to PH , acidosis causes increase in ionized fraction , while alkalosis decrease it . - respiratory alkalosis due to hyperventilation results in tetany with an apparently normal total serum Ca. - Normal serum level 8.5-10 mg/dl. - (4.25 – 5.25 mEq/L or 2.2 – 2.5 m mol /L). - Serum Ca. level likely to be modified by vit. D , parathormone , calcitonin & the state of the renal & bowel functionELECTROLYTES IMBLANCE
Sodium depletion [Hyponatremia] Aetiology :- 1- GIT loss ,vomiting ,suction, diarrhea, intestinal obst. [gastric ,intestinal ,biliary, pancreatic fluid rich in sodium , lost by suction or vomiting] small intestinal & biliary fistula , diarrhea may lead to hypo natremia . 2- Loss of ECF externally [burns, marked sweating ] or internally as third space [peritonitis, ascitis or ileus.] Third space is acollection of ECF that is not functioning in maintaining fluid & electrolytes balance .examples tissue odema due to trauma , infections .ascitis intestinal content in paralytic ileus. 3- Extensive urine sodium loss [diuretics , salt wasting , nephritis & adrenal failure.] 4- Blood loss. 5- Restricted dietary intake. 6- Adrenocortical insufficiency result in hyponatremia with elevated K+.Clinical Features:-
The symptoms and signs of sodium depletion are caused by decreased ECF volume.-The eyes are sunken and the face is drawn, in infants ant. fontanelle ,is depressed, dry wrinkled skin. -The tongue is coated and dry .- Thirst is not evident as in water depletion .- tachycardia , hypotension , shock due to hypo volaemia .- peripheral veins are contracted.- Low CVP.- Urine , dark ,scanty , increase specific gravity.- Haemoconcentration.Treatment :- - Restoration of ECF volume by appropriate amounts of sodium containing fluid such as normal saline [sodium chloride 0.9%] or ringer’s solution. - Blood loss should be replaced by blood .
Sodium Excess [Hypernatraemia ]
Causes :1- Inpatient given excess 0.9% solution post operatively.2- Hyperaldosteronism :primary [conn’s syndrome]3- Cushing’s syndrome.Clinical features:1- Slight puffiness of the face is the only early sign.2- the only reliable clinical sign of total body sodium excess is odema.3- Weight gain parallels accumulation of ECF .4- Hypertension.Rx:--sodium restriction and careful use of diuretics.Potassium Depletion [ Hypokalaemia ]
Since serum K+ content represent small amount of total body K+ small reduction in serum level reflect large loss of K+. Aetiology:- 1-extensive vomiting ,pyloric stenosis , intestinal obst. , paralytic ileus, prolonged I.V fluid normal saline with suction. 2-External alimentary fistulae. 3-Diarrhea severe as cholera . Ulcerative colitis ,villous tumor of the rectum or ileostomy dysfunction. 4-certain type of diuretic like furosmide. 5-alkalosis due to shift of K+ in to cells with out change in body K+. 6-Hyperaldosteronism.aldosteron cause k+ loss. Consequences:- -Hypokalaemia raises membrane excitation potentials making nerves and muscles less excitable . -Risk of supra ventricular arrhythmias. -Decrease K+ in pt. with liver disease lead to hepatic coma.Clinical Features:-
-Most pt. are asymptomatic . -Early signs of K+ loss malaise ,weakness ,speech slow and slurred . -Paralytic ileus and distension . -Muscular paresis in severe loss of K+, weakness of respiratory muscles lead to inadequate ventilation & atelectasis. -ECG prolonged QT interval , depression of ST segment , inversion of T wave . Treatment -At normal PH the K+ deficit calculated as follow [4.5-serumK+con.]*100. -The required amount of K+ given by infusion with other solution , if given directly I.V it is dangerous ,because hyperkalemia causes cardiac arrhythmia and asystole .Safe roles for giving K+:- 1-Urine out put at least 40 ml/hr. 2-not more than 40 m mol/liter. 3-not faster than 40 m mol/hr.