FLUID THERAPY

Body Fluid CompartmentsBody Fluid Compartments::

ICF:ICF:55%~75%55%~75%

IntravascularIntravascularplasmaplasma

X 50~70% X 50~70% lean body weightlean body weight

ExtravascularExtravascularInterstitial Interstitial

fluidfluid

TBWTBW

ECFECF

3/4

1/4

• Male (55%) > female (45%)• Most concentrated in skeletal muscle• TBW=0.6xBW• ICF=0.4xBW• ECF=0.2xBW

2/3

1/3

Total body water (TBW)

• TBW varies with age ,gender and body habitus

• In adult males= 55% of body weight

• In adult female=45% of body weight

• In infant = 80% of body weight

• Obese patients have less TBW per Kg than lean body adult.

1= Intracellular fluid (ICF)=55% TBW or 30%-40% BW

2= Extracellular fluid (ECF) =45%TBW or 20% BW

• Interstitial fluid =15% of body weight

• Intravascular fluid or plasma volume = 5% of body weight

Body compartment fluid

Fluid compartments

ICF

Fluid compartments

ICF

ECF

Interstitial

Plas

ma

Fluid compartments

ICF

ECF

Interstitial

Plas

ma

Fluid compartments

ICF

ECF

Interstitial

Plas

ma

Capillary Membrane

Fluid compartments

ICF

ECF

Interstitial

Plas

ma

Capillary Membrane

Fluid compartments

ICF

ECF

Interstitial

Plas

ma

Capillary Membrane Cell Membrane

Colloid osmotic pressure

ECF

Interstitial

Plas

ma

Capillary Membrane Capillary membrane freely permeable to

water and electrolytes but not to large molecules such as proteins (albumin).

Colloid osmotic pressure

ECF

Interstitial

Plas

ma

Capillary Membrane Capillary membrane freely permeable to

water and electrolytes but not to large molecules such as proteins (albumin).

Colloid osmotic pressure

ECF

Interstitial

Plas

ma

Capillary Membrane Capillary membrane freely permeable to

water and electrolytes but not to large molecules such as proteins (albumin).

The albumin on the plasma side gives rise to a colloid osmotic pressure gradient favouring movement of water into the plasma

H2O

H2O

Colloid osmotic pressure

ECF

Interstitial

Plas

ma

Capillary Membrane Capillary membrane freely permeable to

water and electrolytes but not to large molecules such as proteins (albumin).

The albumin on the plasma side gives rise to a colloid osmotic pressure gradient favouring movement of water into the plasma

This is balanced out by the hydrostatic pressure difference

H2O

H2O120/80

H2O

H2O

Starling equation

Q=Pc-Posm

Cell Membrane

ICF

Cell Membrane

Interstitial

H2O

H2O

Cell membrane is freely permeable to H20 but

Cell Membrane

ICF

Cell Membrane

Na+

K+

Interstitial

H2O

H2O

Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

Cell Membrane

ICF

Cell Membrane

Na-

K+

Interstitial

H2O

H2O

Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

[K+] =4

Cell Membrane

ICF

Cell Membrane

Na-

K+

Interstitial

H2O

H2O

Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

[K+] =4 [K+] =150

Cell Membrane

ICF

Cell Membrane

Na-

K+

Interstitial

H2O

H2O

Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

[K+] =4 [K+] =150

Na+= 144

Cell Membrane

ICF

Cell Membrane

Na-

K+

Interstitial

H2O

H2O

Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

[K+] =4 [K+] =150

Na+= 144Na+= 10

Composition of Body Fluids:Composition of Body Fluids:

Ca 2+

Mg 2+

K+

Na+

Cl-

PO43-

Organic anion

HCO3-

Protein

0

50

50

100

150

100

150

Cations Anions

EC

FICF

Osmolarity = solute/(solute+solvent)Osmolarity = solute/(solute+solvent) Osmolality = solute/solvent (290~310mOsm/L)Osmolality = solute/solvent (290~310mOsm/L) Tonicity = effective osmolalityTonicity = effective osmolality Plasma osmolility = 2 x (Na) + (Glucose/18) + Plasma osmolility = 2 x (Na) + (Glucose/18) +

(Urea/2.8)(Urea/2.8) Plasma tonicity = 2 x (Na) + (Glucose/18)Plasma tonicity = 2 x (Na) + (Glucose/18)

Composition body fluid compartments Ion  

Plasma(mmol/L)

ICF (mmol/L)

Na+ 143 9

K+ 5 135Ca2+ 1,3 <0,8

Mg2+ 0.9 25

Cl- 103 9

HCO3- 24 9

HPO42- 0,4 74

Sulphate- 0,4 19

Protein- 1,14 64

Composition of GI SecretionsComposition of GI Secretions

SourceSource Volume Volume (ml/24h)(ml/24h) NaNa+*+* KK++ ClCl-- HCOHCO33

--

SalivarySalivary 1500 1500 (500~2000)(500~2000) 10 (2~10)10 (2~10) 26 (20~30)26 (20~30) 10 (8~18)10 (8~18) 30 30

StomachStomach 1500 1500 (100~4000)(100~4000) 60 (9~116)60 (9~116) 10 (0~32)10 (0~32) 130 (8~154)130 (8~154) 00

DuodenumDuodenum 100~2000100~2000 140140 5 5 8080 00

IleumIleum 30003000 140 (80~150)140 (80~150) 5 (2~8)5 (2~8) 104 (43~137)104 (43~137) 3030

ColonColon 100-9000100-9000 6060 3030 4040 00

PancreasPancreas 100-800100-800 140 (113~185)140 (113~185) 5 (3~7)5 (3~7) 75 (54~95)75 (54~95) 115115

Bile Bile 50-80050-800 145 (131~164)145 (131~164) 5 (3~12)5 (3~12) 100 (89~180)100 (89~180) 3535

* Average concentration: mmol/L

Sweat: Na 10-70 mEq/LCl 5-60 mEq/LK 1-15 mEq/LMg 0.2-5 mEq/LUrine: Na 50-250 mEq/24hK 30-120 mEq/24hCl 100-250 mEq/24h

Questions to ask before prescribing fluid

• Does my patient need intravenous fluid?

• Why does my patient need intravenous fluid?

• How much and which fluid does he need?

Does he need fluid?

• May be drinking• May be on NG feed/TPN – both of these

contain fluid which counts as maintenance• May be receiving many drug infusions e.g.

antibiotics/paracetamol – can amount to 1+ litre/day

• He may only need a bit of maintenance fluid• This calculation should be done for each

patient

Why does he need fluid?

• Maintenance –water and electrolytes • To supply the daily needs –

(e.g. 4% dextrose/0.18%saline/KCl)• Replacement To replace ongoing losses • know the content of the fluid! (usually

crystalloid)• Resuscitation - e.g.colloid/blood

• To correct an intravascular or extracellular volume deficit

Fluid balance charts

Always calculate the balance between inputs and outputs

Sources of daily water loss

• Urine 1200-1500 ml/d (30ml/hr)

• Sweat 200-400 ml/d

• Lungs 500ml/d

• Feces 100-200 ml/d

Daily Electrolyte loss

NaNa+ 100 mEq 100 mEq

KK+ 100 mEq100 mEq

Cl-Cl- 150 mEq 150 mEq

Daily Requirements

Water 25-35 ml/kg (30)

Sodium approx 1 mmol/kg

Potassium approx 1 mmol/kg

Calories minimum 400 Calories

(i.e. 100 g dextrose)

(calories help to deal with electrolytes normally)

Average Daily Requirements

• 70 kg man needs: 2100 ml H2O 70 mmol Na+

70 mmol K+

70 mmol Cl-

• 50kg man needs 1500 ml H2O 50 mmol Na+

50 mmol K+

50 mmol Cl-

Properties of Commonly Used Crystalloid Properties of Commonly Used Crystalloid SolutionsSolutions

SolutionSolution Electrolyte Electrolyte ContentContent

(mmol/l)(mmol/l)

OsmolalitOsmolality y

(mOsm/k(mOsm/kg)g)

pHpH

0.90.9% NaCl% NaCl NaNa++ 154 154 ClCl- - 154154 308308 5.05.0

Dextrose (4%)-Dextrose (4%)-Saline (0.18%)Saline (0.18%)

NaNa++ 31 31 ClCl- - 3131 286286 4.54.5

5% Dextrose5% Dextrose NilNil NilNil 280280 4.04.0

HartmannHartmann’’s s solutionsolution

NaNa++ 131 131

KK++ 5 5

CaCa++ 2 2

ClCl- - 111111

HCOHCO33- - 2929

276276 6.56.5

Ringer LactateRinger Lactate NaNa++ 130 130

KK++ 4 4

CaCa++ 3 3

ClCl- - 110909

HCOHCO33- - 2828

280280 5.5-75.5-7

MAINTENANCE

If you were on a desert island, would you drink

from the sea or a stream?

0.9% saline is not a maintenance fluid

MAINTENANCE

• Prescribe maintenance if not drinking >6hrs • 4%/0.18% dextrose/saline with 20mmol potassium in

500ml, or 40mmol in 1 litre (1 litre is cheaper). Or no potassium

• Prescribe in ml/hr via a pump.• The correct volume of this by weight per day for

maintenance will provide roughly the correct amount of sodium and potassium for each patient. Maximum 100ml/hr to avoid hyponatraemia.

Potassium

• A normal serum potassium is not an indication that the patient does not need potassium – it just means that their stores haven’t run out yet.

• A low potassium means that losses are high and body stores very low.

• A high potassium may be drug related but commonly is due to acute renal failure – monitor U&Es and do not give extra K.

• Remember that TPN, NG feed and food contain K

Sodium

• We all need some. However most drugs contain sodium so we don’t need to give a lot in fluids unless the patient is losing it.

• Causes of a low Na – too much fluid (commonest cause in hospital!) – fluid restrict

• SIADH inappropriate antidiuretic hormone secretion– pneumonia, brain pathology

• High Na loss – usually upper GI losses – tend to be obvious

4 – 2 – 1 Rule

• 100 – 50 – 20 Rule for daily fluid requirements

• 4 mL/kg for 1st 10 kg• 2 mL/kg for 2nd 10 kg• 1 mL/kg for each additional kg

Maintenance Fluids: Example

• 60 kg female• 1st 10 kg: 4 mL/kg x 10 kg = 40 mL• 2nd 10 kg: 2 mL/kg x 10 kg = 20 mL• Remaining: 60 kg – 20 kg = 40 kg

1 mL/kg x 40 kg = 40 mL• Maintenance Rate = 120 mL/hr

REPLACEMENT

• Losses should be accounted for with replacement fluid: balanced solution( Hartmanns – Ringers Lactate)

• Work out how much patient is losing and replace this with Hartmanns or RL – better to calculate retrospectively and replace.

• Fluid prescriptions for losses must be reviewed regularly and updated.

Fluid Deficits

• Fasting• Bowel Loss (Bowel Prep, vomiting, diarrhea)• Blood Loss

– Trauma– Fractures

• Burns• Sepsis• Pancreatitis

LOSSES

• Upper GI loss: stomach, small bowel ileostomy/fistula/bile leak: high Na and Cl content – may become hypochloraemic and alkalotic – appropriate to use 0.9%NaCl

• Lower GI loss: diarrhoea - lose lots of water and potassium: Hartmanns or RL is appropriate to replace + extra potassium

Insensible Fluid Loss

• Evaporative• Exudative• Tissue Edema (surgical manipulation)• Fluid Sequestration (bowel, lung)• Extent of fluid loss or redistribution (the “Third

Space”) dependent on type of surgical procedure

• Mobilization of Third Space Fluid POD#3

Insensible Fluid Loss

• 4 – 6 – 8 Rule• Replace with Crystalloid (NS, LR, Plasmalyte)• Minor: 4 mL/kg/hr• Moderate: 6 mL/kg/hr• Major: 8 mL/kg/h

Replacement Strategies

• Sweat: D5¼NS + 5 mEq KCl/L

• Gastric: D5½NS + 20 mEq KCl/L

• Biliary/pancreatic: LR• Small Bowel: LR• Colon: LR• 3rd space losses: LR

Example

• 68 kg female for laparoscopic cholecystectomy

• Fasted since midnight, OR start at 8am• Maintenance = 40 + 20 + 48 = 108 mL/hr• Deficit = 108 mL/hr x 8hr = 864 mL • 3rd Space (4mL/kg/hr) = 272 mL/hr

Example

• Intra-operative Fluid Replacement of:– Fluid Deficit 864 mL– Maintenance Fluid 108 mL/hr– 3rd Space Loss 272 mL/hr– Ongoing blood loss (crystalloid vs. colloid)

How much fluid does he need?

• Weight for maintenance 30-35 ml/kg/24hrs

• History, fasting, losses, sepsis, fluid balance charts

• Clinical status, current losses, fluid intake, urine output

• Electrolytes, Hb (may be raised in dehydration)

Shock

• Circulatory failure leading to inadequate perfusion and delivery of oxygen to vital organs

• Blood Pressure is often used as an indirect estimator of tissue perfusion

• Oxygen delivery is an interaction of Cardiac Output, Blood Volume, Systemic Vascular Resistance

DO2

CaO2

CO

Sat %

PaO2

Hgb

HR

SV

Preload

Contractility

Afterload

Types of Shock

• Hypovolemic – most common• Hemorrhagic, occult fluid loss

• Cardiogenic• Ischemia, arrhythmia, valvular, myocardial

depression• Distributive

• Anaphylaxis, sepsis, neurogenic• Obstructive

• Tension pneumo, pericardial tamponade, PE

Types of Shock

Shock States

BPBP CVPCVP PCWPPCWP COCO SVRSVR

HypovolemHypovolemiaia

CardiogeniCardiogenic - LVc - LV

- RV- RV

DistributiveDistributive

ObstructiveObstructive

Hypovolemic Shock

• Most common• Trauma• Blood Loss• Occult fluid loss (GI)• Burns• Pancreatitis• Sepsis (distributive, relative hypovolemia)

Assessment of Stages of Shock

% Blood % Blood Volume Volume lossloss

< 15%< 15% 15 – 30%15 – 30% 30 – 40%30 – 40% >40%>40%

HRHR <100<100 >100>100 >120>120 >140>140

SBPSBP NN N, DBP, N, DBP, postural droppostural drop

Pulse Pulse PressurePressure

N or N or

Cap RefillCap Refill < 3 sec< 3 sec > 3 sec> 3 sec >3 sec or >3 sec or absentabsent

absentabsent

RespResp 14 - 2014 - 20 20 - 3020 - 30 30 - 4030 - 40 >35>35

CNSCNS anxiousanxious v. anxiousv. anxious confusedconfused lethargiclethargic

TreatmentTreatment 1 – 2 L 1 – 2 L crystalloid, crystalloid, + + maintenancmaintenancee

2 L 2 L crystalloid, crystalloid, re-evaluatere-evaluate

2 L crystalloid, re-2 L crystalloid, re-evaluate, replace blood evaluate, replace blood loss 1:3 crystalloid, 1:1 loss 1:3 crystalloid, 1:1 colloid or blood products. colloid or blood products. Urine output >0.5 Urine output >0.5 mL/kg/hrmL/kg/hr

Fluid Resuscitation of Shock

• Crystalloid Solutions– Normal saline– Ringers Lactate solution– Plasmalyte

• Colloid Solutions– Voluven– Emagel– Blood products (albumin, RBC, plasma)

Crystalloids

• Na+ main osmotically active particle• Useful for volume expansion (mainly interstitial space)• For maintenance infusion• Correction of electrolyte abnormality

CrystalloidsCrystalloids

• Isotonic crystalloids - Lactated Ringer’s, 0.9% NaCl - 25% remain intravascularly

• Hypertonic saline solutions - 3% NaCl

• Hypotonic solutions - D5W, 0.45% NaCl - < 10% remain intra- vascularly, inadequate for fluid resuscitation

Colloids vs Crystalloids

Crystalloid Solutions

• Normal Saline• Lactated Ringers Solution• Plasmalyte• Require 3:1 replacement of volume loss• e.g. estimate 1 L blood loss, require 3 L of

crystalloid to replace volume

Colloid SolutionsColloid Solutions

• Contain high molecular weight substancesdo not readily migrate across capillary walls

• Preparations - Albumin: 5%, 25% - Hydoxyethyl starches ie Voluven - Dextrans - Gelatins

- Fresh Frozen Plasma

The colloids are mainly in the intravascular compartment for a period lasting more than

crystalloids

Fluids and Cardiac Index

What colloid?Fluids Average molecular

weight(kilodaltons)Oncotic pressure

∆plasma volumevolume infused

Duration

Albumina 25%

69 70 4.0-5.0 16 hr

Destrano40 10%

26 40 1.0-1.5 6 hr

Hetastarch 6%

450 30 1.0-1.3 10 hr

Voluven 130 36 1.0 6 hr

Emagel 35 30 0.7-0.8 1-3 hr

Albumina 5%

69 20 0.7-1.3 16 hr

Albumin

• MW 69,000 Da• Main protein "transport" in the blood• Responsible for 75% of the COP• Can act as a "buffer"• Can inhibit the aggregation PTLs and factor

Xa by ATIII• Solutions at 5% and 25%

Disputes on the use of albumin

• Cochrane Injuries Group Albumin Reviewers.Human albumin administration in critically ill patients:systematic review of randomized, controlled trials. Br.Med.J. 1998;317:235-240.

• Choi PT, Yip G, Quinonez LG et al. Cristalloids vs. Colloids in fluid resuscitation: a systematic review. Crit Care Med. 1999;27:200-210.

• Wilkes MN, Navickis RJ. Patient survival after human albumin administration: a meta-analysis of randomized, controlled trials. Ann Intern Med. 2001;135:149-164.

• SAFE Study Investigators. A comparison of albumin and saline for fluid resuscitation in the intensive care unit. N Engl J Med 2004; 350:2247-2256.

• Vincent JL, Navickis RJ, Wilkes MM. Morbidity in hospedalized patients receiving human serum albumin: a meta-analysis of randomized, controlled trials. Crit Care Med. 2004;32:2029-2038.

Dextrans

• Polydisperse polymers of glucose (10% dextran 40 and 6% dextran 70)

• High power oncotic (directly proportional to the size)

• Remain in the vascular compartment in a variable depending on the size

• Elimination almost exclusively via the kidneys• Also used to reduce blood viscosity

Adverse effects of Dextrans

• Anaphylactic reactions (> Gelatin and HES)

• Renal dysfunction or IRA

• Interference with Coagulation

Gelatins

• MW 5000-50000 • Are polydisperse polypeptides derived from the

degradation of bovine collagen• Increase in the volume less than the amount infused

because they go into the interstitial space and are rapidly eliminated by the kidney

• Not accumulate in the blood• Can alter the haemostasis• Do not affect renal function

Gelatins

• Cross-linked or ossipoligelatin (Gelofundiol)

• Urea-cross-linked gelatin (Haemacel)

• Modified fluid gelatins or succinilate(Gelofusin)

Hydroxyethyl starch (HES)

• Colloids synthesis of derivatives from amylopectin (Corn or potato)

• The natural starches are unstable and rapidly hydrolyzed; the replacement of the hydroxyl group with a hydroxyethyl group in position C2-C3-C6 increases its solubility and retards the hydrolysis

• Good ability to expand the plasma volume• High capacity to bind water (20-30 ml / g)

Hydroxyethyl starch (HES) EFFECTS ON THE CIRCLE

• Increases the intravascular volume

• Improves the flow in the microcirculation

• Reduces blood viscosity and therefore the Vascular resistances

• Appears to reduce capillary permeability due to inflammation

(Seal the leakage)

EFFECTS ON RENAL FUNCTION • Recent studies show that patients

treated with HES may have renal dysfunction

• Some histological studies of transplanted kidneys showed tubular alterations but do not give any symptoms to the recipient (urinary hyperviscosity)

• Adequate hydration with crystalloid prevent these adverse effects on renal function

Hydroxyethyl starch (HES) EFFECTS ON

COAGULATION• Possible negative effects

that vary with the type of HES: those of "first generation" have effects more severe

• Mechanism of action is not entirely clear: possible inhibition of factor VIIIc and vWF and platelet function

STORAGE

• Itching for accumulation in the peripheral nerves even after a month

• Predominantly affects the hydroxyethyl starch "first generation"

Is hydroxyethyl starch safe for the kidney?

• Association of hydroxyethyl starch administration with mortality and acute kidney injury in critically ill patients requiring volume resuscitation: a systematic review and meta-analysis. Zarychanski R, Abou-Setta AM, Turgeon AF, Houston BL, McIntyre L, Marshall JC, Fergusson DA. JAMA. 2013 Feb 20;309(7):678-88

• Hydroxyethyl starch or saline for fluid resuscitation in intensive care . Myburgh JA, Finfer S, Bellomo R, Billot L, Cass A, Gattas D, Glass P, Lipman J, Liu B, McArthur C, McGuinness S, Rajbhandari D, Taylor CB, Webb SA; CHEST Investigators; Australian and New Zealand Intensive Care Society Clinical Trials Group.N Engl J Med. 2012 Nov 15;367(20):1901-11.

All colloids exert a negative effect on haemostasis!

• Dilution effect• Specific action on coagulation factors and platelets

De Jonge E., Levi M. Effects of different plasma substitutes on blood coagulation: a comparative review. Crit.Care Med. 2001;29:1261-7.

Colloid Solutions

• Voluven• Emagel• Albumin 5%• Fresh Frozen Plasma• Replacement of lost volume in 1:1 ratio

Eternal war between Colloids and Crystalloids!!

There is no ideal Fluid resuscitation!

• Colloids versus crystalloids for fluid resuscitation in critically ill patients.Perel P, Roberts I, Ker K. Cochrane Database Syst Rev. 2013 Feb 28;2:CD000567.

DO2

CaO2

CO

Sat %

PaO2

Hgb

HR

SV

Preload

Contractility

Afterload

Oxygen Carrying Capacity

• Only RBC contribute to oxygen carrying capacity (hemoglobin)

• Replacement with all other solutions will– support volume– Improve end organ perfusion– Will NOT provide additional oxygen carrying

capacity

RBC Transfusion

• BC Red Cell Transfusion Guidelines recommend transfusion only to keep Hgb >70 g/dL unless– Comorbid disease necessitating higher transfusion

trigger (CAD, pulmonary disease, sepsis)– Hemodynamic instability despite adequate fluid

resuscitation

Centro per lo Shock e il Trauma, Azienda Ospedaliera S. Camillo-Forlanini; Roma - Italy

Fluid therapy and haemostasis

Goals of Fluid Resuscitation

• Easily measured

– Mentation– Blood Pressure– Heart Rate– Jugular Venous Pressure– Urine Output

Goals of Fluid Resuscitation

• A little less easily measured

– Central Venous Pressure (CVP)– Left Atrial Pressure– Central Venous Oxygen Saturation SCVO2

Mixed Venous Oxygenation

• Used as a surrogate marker of end organ perfusion and oxygen delivery

• Should be interpreted in context of other clinical information

• True mixed venous is drawn from the pulmonary artery (mixing of venous blood from upper and lower body)

• Often sample will be drawn from central venous catheter (superior vena cava, R atrium)

Mixed Venous Oxygenation

• Normal oxygen saturation of venous blood 68% – 77%

• Low SCVO2

– Tissues are extracting far more oxygen than usual, reflecting sub-optimal tissue perfusion (and oxygenation)

• Following trends of SCVO2 to guide resuscitation (fluids, RBC, inotropes, vasopressors)

Goals of Fluid Resuscitation

• A bit more of a pain to measure

– Pulmonary Capillary Wedge Pressure (PCWP)– Systemic Vascular Resistance (SVR)– Cardiac Output / Cardiac Index

Pinsky MR, Payen D. Functional hemodynamic monitoring. Crit Care 2005;9:566-572

GRAZIE PER L’ATTENZIONE !!!

The End