Upload
laurence-christopher-randall
View
229
Download
0
Embed Size (px)
Citation preview
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