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V - Disease transmission:
* Bacterial: Brucellosis, syphilis.
* Viral: HBV, HCV, HIV, Epstein Barr virus, Cytomegalovirus.
* Parasitic: Malaria and toxoplasmosis.
VI – Massive blood transfusion:
* It is transfusion of a volume of blood more than the recipient’s
blood volume in less than 24hrs.
1. Hypothermia:
Due to rapid infusion of a large amount of cold blood.
It can cause cardiac dysarrhythmias or even arrest.
2. Citrate intoxication:
* It decreases the ionized Calcium causing hypocalcaemia.
* Citrate is either metabolized to bicarbonate or binds to Ca++
(chelating effect).
* Clinically: Parasthesia, muscle tremors or tetany.
* Treatment: Only in symptomatic patients I.V Calcium gluconate
should be given.
3. Hyperkalemia:
* It is due to release of Potassium ions from RBC lysis in banked
blood or in fast transfusion.
* RBC lysis in stored blood due to loss of cell membrane integrity
due to hypoxia.
* Rarely causing clinical problems.
4. Acidosis:
* RBCs hypoxia due to storage predisposes to anaerobic metabolism
that releases lactate resulting in acidosis.
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Treatment:
I.V. fluid usually will correct acidosis.
I.V Sodium bicarbonate +/-.
5. Loss of platelets function:
Because of the short shelf life of platelets, stored blood contains no
platelets.
6. Coagulation factor deficiency:
* Due to the dilutional effect of massive transfusion especially factors
V and VIII.
7. Jaundice:
* Due to transfusion of haemolysed RBCs.
8. Coagulation failure:
* Dilution of clotting factors, platelets
* DIC
9. Pulmonary insufficiency:
* Usually due to circulating overload or sepsis.
Autologous blood transfusion
It is transfusion of patient’s by his own blood How ?
1) Preoperative donation of 2-4 units [ 1unit/wk] and then preserved
to be given at or after elective operation.
2) Intraoperative donation in normovolumic patient removal of 1-2
units of whole blood during induction of anaesthesia with
replacement by crystalloids.
51
Water And Electrolytes
The volume and biochemical composition of extra cellular (ECF) and
intra cellular (ICF) fluid compartments in the body remain constant
under normal circumstances. Many diseases result in changes of either
ECF leading to abnormalities such as oedema, hypotension or
hypertension or of electrolytes composition of ECF.
Fluid compartments:
Water accounts about 60 % of total body weight in adult male and
about 55 % in adult female. The body water is distributed between
two major fluid compartments:
1) Intracellular fluid (ICF) 2/3=67% of total body weight (TBW)
=28L.
2) Extracellular fluid (ECF) 1/3,which is divided into:
a) Interstitial fluid 25% of TBW=10.5L
b) Intra vascular fluid 8% of TBW=3.5L
The distribution of ECF between vascular and extra vascular is
determined by equilibrium between:
1) Hydrostatic pressure.
2) Oncotic pressure.
53
Electrolyte and Water Control Mechanisms
The kidneys and the lungs regulate the body’s electrolytes and water
and regulate the chemical composition of blood, providing primary
control over electrolytes and water in body fluids.
work in conjunction with the kidneys and lungs to regulate and
maintain normal water and electrolyte balance within the body.
The kidneys have the largest responsibility for maintaining blood
chemistry, and in concert with the lungs are responsible for regulating
the acid-base balance within the blood. These processes involve both
electrolytes and water. The kidneys filter the blood to remove harmful
metabolic acids and wastes and reabsorb those substances the body
needs. They help control plasma ion concentration and maintain pH
by removing strong ions such as Na+ and Cl- from plasma into urine.
The kidneys also control blood volume by regulating the amount of
water in extracellular fluid. Two hormones, aldosterone and
antidiuretic hormone (ADH) help the kidneys control the fluid volume
of blood. When water is lost from the body, blood volume decreases.
This leads to increased production of aldosterone and ADH. Elevated
aldosterone increases Na+ pump activity in the kidney tubules. As a
Individual cells
result, more Na+ is removed from the distal tubules and concentrated
within the kidney rather than being excreted. This high concentration
of Na+ in kidney tissue creates an osmotic gradient that pulls water
out of the tubules. Elevated ADH works in conjunction with
aldosterone by increasing the permeability of the tubules to water,
allowing water to follow Na+ out of the tubules, thereby reducing
urinary water loss.
54
Renal physiology
The lungs play an important role in regulating plasma CO2 and pH.
Since CO2 is a gas, the term partial pressure, PCO2, is used to
describe its concentration in liquids. Changes in respiration rate relate
to changes in the partial pressure of CO2. For example, CO2 is
produced during exercise and is removed from muscle tissue by the
blood, increasing PCO2. To quickly rid the blood of excess CO2,
respiration rate increases. In this process, CO2 from the muscle
combines with water to form carbonic acid in the blood, which then
dissociates to H+ and bicarbonate ions (HCO3-). Bicarbonate is the
primary storage and transportation form of CO2 in plasma. In the
lungs, this process is reversed with CO2 and water being exhaled.
55
As the rate of CO2 production increases, PCO2, [HCO3-] and respiration
rate increase. If CO2 production outstrips the lungs’ ability to convert
HCO3- to water and CO2, plasma [HCO3-] will continue to rise. Plasma
[H+] will also rise, offsetting these, causing plasma pH to decrease.
Acidosis = ↑PCO2,↑HCO
Alkalosis = ↓PCO2,↓HCO
-
,↓pH
3
-
,↑pH
3
The ECV is controlled by the total body content of Na, which is
controlled tightly by renal excretion of Na, this achieved by activation
of receptors which respond to ECV rather than the changes in Na
concentration, and these volume receptors can be divided into:
(a) extra renal baroreceptors.
(b) intrarenal baroreceptors.
The extra renal baroreceptors are located in vascular tree in left atrium,
major thoracic veins and sinus body and aortic arch.
The receptors are stimulated by reduction of circulating volume,this
leading to sympathetic nerve activation and rise in catecholamines,in
addition,the volume receptors in the cardiac atria will release atrial
natri uretic peptide (ANP).
The intra renal receptors in the wall of the afferent glomerular artrioles
respond via the juxtraglomerular apparatus to change in renal perfusion
and control of the activity of the renin-angiotension-adosterone system.
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Fluid disorders are classified into :
I- Disturbance of the volume.
II- Disturbance of the concentration.
I- Disturbance of the volume:
A - Increase of ECF volume:
This occurs in many diseases and the physical signs depend on the
distribution of excess either is local or systemic, subsequently this
depends on:
a- Venous tone.
b- Capillary permeability.
c- Oncotic pressure.
d- Lymphatic drainage.
Clinical features:
1. Oedema in the ankle and sacral area.
2. Pulmonary oedema.
3. Pleural effusion, pericardial effusion, and ascitis
Causes of increase ECF:
1- Heart failure:
Decrease of cardiac output will decrease the blood pressure that
stimulates baro receptors and decrease renal perfusion. This will
stimulate the juxtra glomerular apparatus (JGA) leading to activation of
renin-angiotension-aldosterone system (R.A.A), which results in Na
and H2O retention and increase E.C.F leading to increase of venous
pressure and increase flux from capillary to inerstitium and oedema
2- Hypoalbuminaemia:
Decrease oncotic pressure will result in loss of water from vascular
space to the interstitial space and oedema.
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3-Hepatic cirrhosis:
Hypoalbuminaemia and decrease in aldosterone metabolism, will lead
to activation of rennin-angiotensin-aldosterone system.
4- Renal impairment:
a. Acute nephrotic syndrome.
b. C.R.F.(oligouric)
c. Renal artery stenosis
Treatment: The first main step is treatment of the underlying cause.
1. Na restriction.
2. Bed rest.
3. Diuretic agents.
4. Loop diuretic e.g. frusemide
5. Thiazide diuretic e.g. hydrochlorothiazide.
6. Carbonic anhydrase inhibitors e.g. acetazolamide.
7. K sparing e.g. spironolactone.
B- Decrease in ECF:
Deficiency of Na and H2o causes shrinking of both,the interstitial and
blood volume, also may have profound effect on organ function.
* Clinical features: Symptoms: Thirst, muscle cramps, nausea and
vomiting, postural dizziness. In sever depletion of volume cause
hypotension, impaired cerebral perfusion causing confusion and coma.
a. Signs:
1. Loss of skin turgor.
2. Dry mucous membrane.
3. Skin cold due to peripheral vasoconstriction.
4. Tachycardia.
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5. Decrease blood pressure.
6. Postural hypotension.
7. Low J.V.P or central venous pressure.
8. Decreased urine output.
b. Causes:
1- Haemorrhage, which may be internal (e.g. rupture aortic aneurysm)
or external.
2- Burns.
3- Gastrointestinal losses:-vomiting, diarrhea, ileostomy loss.
4- Renal impairment (polyuria):-diuretics, diabetes mellitus, sickle
cell disease.
* Treatment:
Treatment of the cause and replacement of fluid loss and correction of
the electrolyte deficit
II- Disturbance of concentration:
The responsible factor for osmolarity of ECF is the sodium,normal
plasma osmolality = 280-290m.osm\kg.
A- Hyponatraemia:
- Defined as serum Na < 135meq\l.
- It can be with: 1- low ECV 2- normal ECV 3- Excess of ECV.
* Causes of hyponatraemia with decreased ECV:
1-The gut: vomiting,diarrhoea, haemorrhage.
2-Kidney:
a- Adrenocortical insufficiency.
b- Excessive use of diuretics.
c-Osmotic diuresis (e.g. hyperglycemia, sever uremia).
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