fluid balance& iv fluids -...
TRANSCRIPT
Dr Mere Kende
MBBS, Mmed (Path), MACTM, MAACB, MACRRM
Lecturer- SMHS
Fluid Balance& IV Fluids
Outline
Normal Body Fluid Physiology Types and composition of Parenteral Fluids Indications for IV Fluids Specific replacement Fluids Calculating Minimal fluid requirement Complications of IV Fluids Burn Fluid Management IV Fluids in Shock Treatment Examples of calculating IVF requirement
Principles of Fluids and Electrolytes
Fluid Compartments
Example: 70-kg male
Total Body Water: 42,000 mL (60% of BW)
• Intracellular: 28,000 mL (40% of BW)
• Extracellular: 14,000 mL (20% of BW)
• Plasma: 3500 mL (5% of BW)
• Interstitial: 10,500 mL (15% of BW)
Composition of Body Fluids
Fluid distribution
Total
Body
water
(ml/kg)
IC Fluids
(ml/kg)
EC Fluids
(ml/kg)
Blood
Volume
(ml/kg)
Neonate 800
(80%BW) 350 450 96
Infant 700 400 300 80
Child 650 400 250 70
Adult 600 (60% BW)
400 200 60
Total Blood Volume (TBV)
TBV = 5600 mL (5-8% of BW)
Red Blood Cell Mass
Male, 20–36 mL/kg (1.15–1.21 L/m2);
female, 19–31 mL/kg (0.95–1.0 L/m2
Water Balance
• 70-kg male
The minimum obligate water requirement
to maintain homeostasis (assuming normal
temperature and renal concentrating ability
and minimal solute [urea, salt] excretion) is
about 800 mL/d, which would yield 500
mL of urine/day.
“Normal” Intake: 2500 mL/d (about 35
mL/kg/d baseline)
Oral liquids: 1500 mL
Oral solids: 700 mL
Metabolic (endogenous): 300 mL
“Normal” Output: 1400–2300 mL/d
1. Urine: 800–1500 mL
2. 2. Stool: 250 mL
3. Insensible loss: 600–900 mL (lungs and
skin).
(With fever, each degree above 37°C adds
2.5 mL/kg/d to insensible loss; insensible
losses are decreased if a patient is on a
ventilator; free water gain may occur from
humidified ventilation.)
Electrolyte Requirements
70-kg adult, unless otherwise specified
Sodium (as NaCl): 80–120 mmol/d
And Pediatric patients, 3–4 mmol/kg/ 24 h
Chloride: 80–120 mEq (mmol)/d, as NaCl
Potassium: 50–100 mmol/d) (Pediatric
patients, 2–3 mmol/kg/24 h ).
Note: 1gram KCl- has 13mmol/L potassium’
In the absence of hypokalemia and with normal
renal function, most of this is excreted in the
urine. Of the total amount of potassium, 98% is
intracellular, and 2% is extracellular.
Thus, assuming the serum potassium level is normal, about 4.5 mmol/L (mEq/L), the total extracellular pool of K+ = 4.5 × 14 L = 63mmol.
Potassium is easily interchanged between intracellular and extracellular stores under conditions such as acidosis. Potassium demands increase with diuresis and building of new body tissues (anabolic states).
Calcium: 1–3 gm/d,
Most of which is secreted by the GI tract. Routine
administration is not needed in the absence of
specific indications.
Magnesium: 20 mEq/d (mmol/d).
Routine administration is not needed in the absence of
specific indications, such as parenteral
hyperalimentation, massive diuresis, ethanol
abuse (frequently needed) or preeclampsia.
Glucose Requirements
100–200 g/d (65–75 g/d/m2). i.e., 2-4litres of 5% dextrose solution
During starvation, caloric needs are supplied by body fat and protein; the majority of protein comes from the skeletal muscles. Every gram of nitrogen in the urine represents 6.25 g of protein broken down.
The protein-sparing effect is one of the goals of basic IV therapy. The administration of at least 100 g of glucose/d reduces protein loss by more than one-half. Virtually all IV fluid solutions supply glucose as dextrose (pure dextrorotatory glucose).
Pediatric patients require about 100–200 mg/kg/h.
COMPOSITION OF PARENTERAL FLUIDS
Parenteral fluids are generally classified based on Molecular Weight (MW) and Oncotic Pressure.
Colloids (MW >8000)- High Oncotic pressure (albumin)
crystalloids (MW <8000) - Low Oncotic Pressure (Dextrose)
Crystalloids
Colloids
• Albumin
• Blood products (RBCs, single-donor plasma, etc)
• Plasma protein fraction (Plasmanate)
.Synthetic colloids (hetastarch [Hespan], dextran)
Hartmann’s +/-5% glucose
Na+ 130mmol/L
Cl- 110 mml/L
K+ 5 mmol/L
Lactate 30 mmol/L
Ca++ 2 mmol/L
Baseline Fluid Requirement
Afebrile 70-kg Adult: 35 mL/kg/24 h
If not a 70-kg Adult:
Calculate the water requirement according to the
following “kg method”.
“kg method”
• For the 1st 10 kg of body weight: 100
mL/kg/d plus
• For the 2nd 10 kg of body weight: 50
mL/kg/d plus
• For the weight above 20 kg: 20 mL/kg/d
What is the minimum requirement?
70kg Man: D51/4NS with 20mmol/L KCl at 125ml/hr
(3L free water/day)
Adult Patients:
Use D51/4NS
Determine water requirement ‘kg method’
Divide by 24hr to determine the hourly rate
Paediatric patients:
Use the same solution as adults
“Kg method” vs”‘Meter square method”
Meter Squared method
Maintenance Fluid –
Calculate:1500/m2/day
Divide by 24hr to get the flow rate per hour
To calculate SA, use the ‘rules of sixes’
normogram
‘Rules of Sixes’ Normogram for Calculating Fluids
in Children
Weight- Pound-lbs (kg) Body Surface Area (m2) 3 (1.4) 0.1 6 (2.7) 0.2 12 (5.4) 0.3 18 (8.2) 0.4 24 (10.9) 0.5 30 (13.6) 0.6 36 (16.3) 0.7 42 (19.5) 0.8 48 (21.8) 0.9 60 (27.2) 1.0
After 60 lb, add 0.1 for each additional 10lb After 100 lb (45kg) treat as adult
Formal Body Surface Area Chart
2kg
40cm
0.14
Indications for IV Fluids
Indications: KVO
IV antibiotics/medications
Too sick/not eating well
Awaiting OT
Blood Transfusion
Blood Loss/Dehydration
Medical procedures
Cautions:
Children Brain injury
Elderly Alcohol Intoxication
Pneumonia Lung Infection
Renal Failure Heart failure
Diabetic ketoacidosis Electrolyte Disorders
What fluid to Use? General Principles
Avoid IV Fluids unless necessary
Consider benefits & Risks
Insert large Bore Needle (size 14-18) for urgent resuscitation
Choose a Proximal large veins
Avoid lower limbs if possible (risk of DVT/thrombophebitis)
General principles of IV Fluids
Minimal two attempts/failures in IV insertion -allow another colleague to try
Take as much time to search for ‘good vein
Intraosseus/CV line infusion or cut-down may be required (slide)
Adequately secure IV line
Consider risk of infection
IV line should ideally be dated, changed every 3 days
Intraosseous sites
Specific Replacement Fluids
Maintenance Fluid- Dextrose saline solution (eg D5 ½
NS)
Antibiotic Infusion ? Dextrose/saline
Issue of incompatibility
Presence of electrolyte disorders
Heart Failure
Renal Failure
Hypertension
Pyeloric stenosis- Normal Saline
Renal calculi –1/2, 1/3 strength NS or Dextrose solution
Hypokalemia – N/Saline with 20-40mmol KCL/hr
Hyponatremia- 0.9% N/S, avoid dextrose/low strength
N/S (higher % N/S if necessary)
Heat Stroke – Normal Saline
Burn Patient- Normal Saline (+/-colloids/Blood)
GIT Loss- Normal Saline +/KCl
Gastric Loss (NGT, emesis)- D5 ½ NS with 20mmol/L KCL
Diarrhoea: D5LR (hartmans) with 15mmol/L KCl. Use BW as
replacement guide (about 1L for each kg)
Bile loss: D5LR (Hartman’s) with 25mmol/L (1/2 amp) NaHCO3-
ml for ml
Pancreatic loss: D5LR with 50mmol/L (1amp) NaHCO3- ml for
ml
Diabetic Ketoacidosis-
start with N/saline and insulin infusion/ sliding scale, switch to
dextrose when glucose is <15mmol/L,
continue dextrose insulin until acidosis and dehydration
corrected,
K+ may be required later
Haemorrhage Shock –
1st choice Hartman’s/Ringer’s Lactate (warmed)
2nd Choice N/S (risk of hyperchloraemic acidosis with impaired
RF)
Colloid with caution (Burn patients)
Blood Transfusion if in shock >30-40% blood loss
Resuscitation/Shock----(except cardiogenic)
Use crystalloid -Normal Saline/Hartmans preferred
Amount replaced – approx 3mls blood lost requires 1ml crystalloid
Blood transfusion may be required if hemorrhaging/anaemic or not responding to crystalloids or more than allowable blood loss (>30%)
Aim –BP systolic >100mmHg, HR <120/min, Urine Output >0.5ml/kg/hr
Estimated Fluid and Blood Losses based on
Patient’s (70kg) Initial Presentation (ATLS)
Blood Loss CLASS I Class II Class III Class IV
Blood Loss (ml) Up to 750 750-1500 1500-2000 >2000
% Blood Loss Up to
15%
15-30% 30-40% >40%
PR
BP <100 >100 >120 >140
Pulse Pressure
(mmHg)
normal normal decreased decreased
RR 14-20 20-30 30-40 >35
Urine Output
(ml/hr)
>30 20-30 5-15 Negligible
CNS/mental Status Slight
anxious
Mildly anxious Anxious,
confused
Confused, lethargic
Fluid Replacement
(3:1)
crystalloid crystalloid Crystalloid
& Blood
Crystalloid & Blood
IVF in Burn Patient ABC
Assess % Burn
IVF resuscitation
Prevent On-going Loss
Monitor Complications
Prevent Infection
Prevent Contractures
Burn Patients:
Use the Parkland or
Rule of Nines Formula
Parkland Formula
Calculate Total Fluid requirement during
first 24hr:
=% Body burn x BW (kg) x 4ml
Parkland formula
Total fluid requirement in 24 hours =
4 ml×(total burn surface area (%))×(body weight (kg))
Replace over 24hrs
½ over 1st 8hr (from time of burn)
¼ over 2nd 8hr
¼ over 3rd 8hr
Children receive maintenance fluid in addition, at hourly
rate of;
4 ml/kg for first 10 kg of body weight plus
2 ml/kg for second 10 kg of body weight plus
1 ml/kg for > 20 kg of body weight
“Rules of Nine’
Used to estimate % body burn in adults
Estimation of Fluid loss (ml)= 25 x % Body burn x m2 BSA
This system is used to estimate ongoing fluid losses from a burn until it is healed or grafted
How to Assess % Burn?-3 Methods
Method1. Palmar surface—
The surface area of a patient’s palm (including fingers) is roughly
1% of total body surface area.
Palm surface are can be used to estimate relatively small
burns ( < 15% of total surface area) or very large burns ( >
85%, when unburnt skin is counted).
For medium sized burns, it is inaccurate.
Method 2. Wallace rule of nines—
This is a good, quick way of estimating medium to large burns in
adults.
The body is divided into areas of 9%, and the total burn area
can be calculated.
In adults, this is reasonable method. It is not accurate in
children.
Method 3. Lund and Browder chart—
This chart, if used correctly, is the most accurate method.
It compensates for the variation in body shape with age and
therefore can give an accurate assessment of burns area in
children.
Aim For Normal Urine Output
Adult: 0.5ml/kg/hr
Children 1ml/kg/hr
Infants <1yr 2ml/kg/hr
Shock Definition/causes of shock
Clinical Features
Management
Urgent Treatment (ABC)
Immediate management
Long term management
Effects of Loss of Fluid?
Decreased cardiac Output (low BP, high PR)
Poor tissue perfusion and oxygenation
HYPOXIA (acidosis)
Impaired Renal perfusion (impaired electrolytes/acidosis)
Anaerobic Metabolism -Lactic Acidosis
Lack of ATP generation
Damage to cell membranes
Swelling and damage to cells and death
SIGNS OF DEHYDRATION-children
MOST RELIABLE IS LOSS OF BODY WEIGHT
OTHERS
PALLOR/POOR CAPILLARY REFILL
DEEP BREATHING
DECREASE SKIN TURGOR
INCREASE D THRIST
OTHER SIGNS OILGURIA, RESTLESSNESS, LETHARGY, SUNKEN EYES,
DRY MOUTH, SUNKEN FONTENALLE, ABSENCE OF TEARS—POOR SENSITIVITY FOR MILD MODERATE DEHYDRATION
For children,
<4% BW loss -------no clinical signs
4-6% BW loss -----clinical signs present
>7% BW loss-------acidosis and acidosis present
IVF Treatment
Bolus:
1-2 litres in adults &
20ml/kg bolus in Children
Assess for Response to initial Resuscitation
Rapid Response Transient
Response
No Response
Vital Signs Return to Normal Transient
improvement,
recurrence of inc HR
& Low BP
Remain abnormal
Estimated Blood
Loss
Minimal 10-20% Moderate & On-
going (20-40%)
Severe >40%
Need for More
crystalloids
Low High high
Need for blood Low Moderate to high Immediate
Blood Preparation Type & Cross Match Type-Specific Emergency blood
Release
Need for operative
intervention
probably Likely Highly likely
Early presence of
surgeon
Yes Yes Yes
How to Assess Adequate Fluid
Response
BP & PR- not very sensitive
CVP & Skin colour-difficult to assess
Volume of Urine Output-sensitive and
prime indicator
Complications of IV Fluids
Pulmonary Oedema
Heart Failure
Increased Intracranial Pressure
Electrolyte Imbalance
Worked examples of burns
resuscitation
A 25 year old man weighing 70 kg with a 30% flame burn was admitted to PMGH ED at 4 pm. His burn occurred at 3 pm. Picked up by ambulance, given IL N/S on transit plus morphine & oxygen
1) Total fluid requirement for first 24 hours. (parkland Formula)
4 ml×(30% total burn surface area)×(70 kg) = 8400 ml in 24 hours
2) Half to be given in first 8 hours, half over the next 16 hours. Will receive (4200 ml) during 0-8 hours and 4200 ml during 8-24 hours
3) Subtract any fluid already received from amount required for first
8 hours.
Has already received 1000 ml from emergency services, and
so needs further 3200 ml in first 8 hours after injury
4) Calculate hourly infusion rate for first 8 hours.
Divide amount of fluid calculated in (3) by time left until it
is 8 hours after burn
Burn occurred at 3 pm, so 8 hour point is 11 pm.
It is now 4 pm, so need 3200 ml over next 7 hours: 3200/7 = 457 ml/hour from 4 pm to 11 pm
5) Calculate hourly infusion rate for next 16 hours
Divide figure in (2) by 16 to give fluid infusion rate Needs 4200 ml over 16 hours: 4200/16 = 262.5 ml/hour from 11 pm to 3 pm next day
How to calculate Maintenance fluid in a
child?
A 24 kg child with a resuscitation burn will need the following maintenance fluid:
4 ml/kg/hour for first 10 kg of weight =
40 ml/hour plus
2 ml/kg/hour for next 10 kg of weight =
20 ml/hour plus
1 ml/kg/hour for next 4 kg of weight =
1×4 kg = 4 ml/hour
Total = 64 ml/hour
References
Advanced Trauma Life Support For Doctors (ATLS) 7th
Edition 2005
L. Gomella, Clinician’s Pocket References , 2007
Primary Care Manual RFDS--Queensland - 2007