Download Blood loss

Complication during anesthesia
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Bradycardia
Tachycardia
Atrial arrhythmia
Ventricular arrhythmia
Heart block
Hypotension
Hypertension
Myocardial ischemia
Cardiac arrest
Embolism
Hypoxemia
Hypercapnia
Hypocapnia
Respiratory obstruction
Intubation problems
Aspiration of gastric content
Adverse drug effects
Malignant hyperthermia
Porpheria
Hypothermia
Hyperthermia
injury
Delayed
recovery
The duration of impaired consciousness depend on :
the drug used
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Volatile with high blood/ gas solubility coefficient
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Barbiturates : large doses
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Benzodiazepines
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opioid with long duration
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The timing of drug use : if given toward the end of the procedur
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Pain : long duration drug
If not :
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Hypoglycemia (diabetic patient)
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Hyperglycemia
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Cerebral pathology
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Hypoxemia
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Hypercapnia
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Hypotension
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Hypothermia
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Hypo – osmolar or TURP syndrom
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Hypothyrodism
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Hepatic & renal failure
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Cyanosis
Postoperative hypoxemia is common & may be caused by many factors
► Detected using a pulse oximeter
Causes of postoperative hypoxemia
► Atelectasis
► Diffusion hypoxia
► Hypoventilation
► Bronchospasim
► Aspiration
► Pnumothorax
► Pulmonary embolism
► Pulmonary oedema
Hypoxemia may be corrected by oxygen or increase concentration of oxygen
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Oxygen therapy device
Nasal cannula :2 L /min =28%, simple ,easy to use & well tolerated. May dry nasal
membrane.
► Simple facemask : 35-50%, simple and easy to use. If flow < 5L/min accumulate
CO2
► Venturi mask : 24, 28, 31, & 60%. Simple, reliable, effective.
► Non- rebreathing mask : 60-90%, tight fitting & flow rate should adjusted to prevent
collapse of reservior bag during inspiration.
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Fluid Management
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All patient except those undergoing the most minor surgical procedures require venous
access & IV fluid therapy.
Some require transfusion of blood or blood component.
Maintenance of a normal intravascular volume is highly desirable in the perioperative
period.
The anesthesiologist should be able to assess intravascular volume accurately & replace
any fluid or deficits & ongoing losses.
Errors in fluid replacement or transfusion may result considerable morbidity or even
death.
physiology
Body water content varies with age & sex as percentage of body weight
TBW
ICF(%)
ECF(%)
► Neonate
75
40
35
► Infant
70
40
30
► Adult male
60
40
20
► Adult female
55
35
20
► Elderly
45
30
15
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Approximately two – third of total body (TBW) is intracellular (ICF) & one third is
extracellular fluid (ECF).
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The ECF is further subdivided into interstial fluid & plasma .
The fate of intravenous fluid
The redistribution of infused fluid within the body will depend on its composition relative
to that of each compartment .
► Salt solutions are excluded from ICF by the cell membrane Na+/ K+ pump .
► Dextrose (5%) behaves like water & is distributed throughout the TBW .
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ECF
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Saline (0.9 %)
ICF
0
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Dextrse ( 5%)
2/3
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These figure demonstrate why large volume of crystaloids are required to expand plasma
volume .
To replace a given blood loss requires 3 times the volume as saline (0.9%) or 9 times the
volume as dextrose (5%) .
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ISF
4/5
1/4
plasma
1/5
1/12
Intravenous fluids
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Intravenous fluid therapy may consist of infusion crystalloid, colloid or accombination of
both.
Crystalloid solutions are aqueous solutions of low- molecular weight ions (salts) with or
without glucose .
Colloid solutions also contain high – molecular weigh substances such as proteins or
large glucose polymers .
Colliod solutions maintain plasma colliod oncotic pressure & for the most part remain
intravascular .
Crystaloid solutions rapidly equilibrate with & distributed throughout the entire ESF
Crystaliod solutions
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A wide variety of solutions are avialable .
Solutions are chosen according to the type of fluid loss being replaced .
Losses primarily due to water loss are replaced with hypotonic solutions .
Losses that involve both water & electrolyte deficits are replaced with isotonic electrolyte
solutions
Glucose is provided in some solutions to maintain tonicity or to prevent ketosis &
hypoglycemia.
Commonly used crystalloid solutions
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Sodium chloride 0.9%
Glucose 5%
Glucose 4% + saline 0.18%
Glucose 5% + saline 0.45%
Lactate ringers (Hartmann solution)
Sodium bicarbonate 8.4%
Colloid solutions
The osmotic activity of the high molecular weight substances in colloids tends to maintain
these solutions intravascularly.
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While the intravascular half – life of a crystalloid solution is 20 – 30 minutes, most colliod
solutions have intravasclar half – lives between 3 – 6 hours .
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The substantial cost & occasional complications associated with colliods tends to limit
their use .
Generally accepted indication for colloids include :
 Fluid resuscitation in patient with severe intravascular fluid deficit (eg. Hemorrhagic
shock) prior to the arrival of blood for transfusion .
 Fluid resuscitation in the presence of severe hypoalbominemia or conditions associated
with large protein losses such as burn .
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Several colloids solutions are generally available :
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Blood derived colloid include :
Albumin 5%
Plasma protein fraction 5%
Synthetic colloids include
Detrose starches
Gelatins
Hetastarch ( Hydroxyethyl starch)
Normal requirment :
Water
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A normothermic 70 – kg man with normal metabolic rate loses approximately 2500 ml of
water / day :
- urin
1500 ml
- faeces 100 ml
- sweat 500 ml
- lung
400 ml
Water is gained from :
- ingested fluid 1500 ml
- food
800 ml
- metabolism
400 ml
Maintenance requirement are therefore approximately 1.5 ml / kg /hr
Sodium ( Na+)
Loss in faeces & sweat is about 10 mmol / day .
► Renal excretion being mainly dependent on dietray intake
► Average requirements are 1 mmol / kg.
► This could be provided by :
- 2500 ml of 4% dextrose with 0.18 saline over 24 hours .
- 2000 ml of 5% dextrose & 500 ml of 0.9% saline over 24 h
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Potassium (K+)
loss is via the same routes as sodium , but renal retension is less efficient .
► The average requirement is 1 mmol / kg .
► This should be added to the infusion regime .
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Abnormal losses
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These are common in surgical patient
They may be sensible or insensible & either overt or covert
Losses from the gut are common eg. Nasogastric suction, diarrhea,
vomiting, or sequestration of fluid within the gut lumen (eg. Intestinal
obstruction) .
Replacement with saline 0.9% with 13 – 20 mmol/L of K+ as KCL .
Increased insensible losses from the skin & lungs occur in presence of
fever & hyperventilation
The usual insensible losses from skin & lung increase by 12% for each 1
C rise in body temperature.
Sequestration of fluid at the site of operative trauma is a form of fluid
loss which is common in surgical patient .
This fluid is frequently referred to as (third space) loss .
Third space losses are not measured easily .
Sequestrated fluid is reabsorbed after 48 – 72 h .
Existing deficits
These occur preoperatively & arise primarily from the gut .
► Dehydration with accompanying salt loss is a common disorder in the acute surgical
patient .
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Assessment of dehydration
This is a clinical assessment based upon the following :
History :
How long has the patient had abnormal loss of fluid ?
► How much has occurred eg. Frequency of of vomiting ?
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Examination
Specific features are :
► Thirst
► Dryness of mucous membrane
► Loss of skin turgor
► Orthostatic hypotension
► Tachycardia
► Reduced jugular venous pulse
► Decreased urin out put
The severity of dehydration may be described clinically as :
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Mild dehydration
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loss of 4% of body weight (approximately 3 L in 70 kg patient)
Reduced skin turgor
Sunken eye
Dry mucous membrane
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Moderate dehydration
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Loss of 5 – 8% body weight (approximately4 – 6 L in 70 kg patient)
Oliguria
Orthostatic hypotension
Tachycardia
Addition to the above
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Sever dehydration
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Loss of 8 – 10 % body weight (7 L in 70 kg patient)
Profound oliguria
Compromised cardiovascular function
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Laboratory assessment
The degree of haemoconcentration & increase in albumin concentration may
be helpful in the absence of anemia & hypoproteinaemia
► Increased blood urea concentration & urin osmolality (>650 mosmo/kg)
confirm the clinical diagnosis
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Perioperative fluid requirements :
Fluid therapy can be divided into :
Maintenance
 Deficit
 Replacement requirment : which is further subdivided into :
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- Blood loss
- Third space loss
Maintenance fluid requirements
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In adult & pediatric patients can be determined by the following formula :(4 : 2 : 1)
Weight
For the first 10 kg
For the next 10- 20 kg
For each kg above 20 kg
Rate
4 ml /kg /h
add 2 ml /kg /h
add 1 ml/ kg /h
Ex. What are maintenance fluid requirement for a 25 – kg child ?
Answer : 40 + 20 + 5 = 65 ml / h
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Usually replaced by D5 ½ NS with 20 meq /L KCL
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Deficit
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In addition to a maintenance infusion , any preoperative fluid deficits must be replaced
Ex. If 5- kg infant has not received oral or intravenous fluid for 4 hours prior to surgery?
A deficit of 80 ml has occurred (5kg x 4ml/kg /h x 4 h)
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Deficit = maintenance x hours of fasting
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preoperative fluid deficit are typically administered with hourly maintenance
requirement in aliquots of :
- 50 % in the first hour
- 25 % in the 2 nd hour
- 25 % in the 3 rd hour
In the example above, a total of 60 ml would be given in the first hour (80/2 + 20 )
► 40 ml would be given in the 2 nd & 3 rd hour (80/4 + 20 )
► Preoperative fluid deficit are usually replaced with a balanced salt solution eg. Lactate ringer
injection .
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Replacement requirements : are subdivided into :
- Blood loss
- Third space loss
Blood loss
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The blood volume of :
- Premature
- Full term neonate
- Infant
- Adult
100 ml /kg
85-90 ml /kg
80 ml /kg
65- 70 ml/kg
Blood loss is typically replaced with non – glucose containing crystalloid eg. 3 ml of
lactated ringer injection for each ml of blood loss
► Or colloid solutions eg. 1 ml of 5% albumin per ml of blood lost .
► Blood loss in excess of 15% of blood volume in adult are usually replaced by infusion of
stored blood
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Third space loss
Is impossible to measure & must be estimated by the extent of surgical procedure .
► One popular guideline is :
- 2 ml/kg/ h for relatively a traumatic surgery eg. Strabismus correction
- 6-10 ml/kg/h for traumatic procedure eg. Abdominal abscess
► Third space loss is usually replaced with lactate ringer injection
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Postoperative requirements
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In the postoperative period, normal maintenance fluid should be given(= 1.5 ml/kg/h) as
4% dextrose with 0.18 saline
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Additional fluid may be required in the following circumstances :
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If blood or serum is lost freom drains
If GIT losses continue ex. From NG tube or fistula
After major surgery eg. Total gastrectomy, when additional water & electrolytes may be
required for 24 – 48 h to replace continuing third space losses
During rewarming if the patient has became hypothermic during surgery
Normally K+ is not administered in the first 24 – 48 h after surgery as endogenous
release of K+ from tissue trauma & catabolism warrants restriction
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