Perioperative Fluid Therapy

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Perioperative Fluid Management Dr. Mizanur Rahman Anesthesiologist Sher-E-Bangladesh Medical College Hospital, Barisal:

Perioperative Fluid Management Dr. Mizanur Rahman Anesthesiologist Sher-E-Bangladesh Medical College Hospital, Barisal

Abstract:

Abstract The enzyme system & metabolic process responsible for maintenance of normal cellular function are dependent on environment with stable electrolyte & PH+ conc. Described by Cloud Bernard 100 yrs ago. Complex homeostatic mechanism have evolved to maintain constancy of internal environment and thus prevent cellular dysfunction.

Cont…..:

Cont….. We the anaesthesiologist are intimately concerned to the surgical operation related fluid therapy. So, to do this maintenance of a normal intravascular volume is highly desirable in perioperative period.

Cont….:

Cont…. The anaesthesiologist should be able to assess intravascular volume accurately and to replace any fluid or electrolyte deficits and ongoing losses. Error in fluid replacement or transfusion may result in considerable morbidity or even death.

Goals of Intraoperative fluid Administration:

Goals of Intraoperative fluid Administration Maintain good tissue perfusion Adequate oxygen delivery Normal electrolyte concentration Normoglycemia & pH

Body weight, Period of fasting Daily loss, Loss due to Preexisting condition/disease % of Dehydration + Loss during operation Composition of fluid, Redistribution of fluid, Molarity, Molality, Molecular wt. Effective osmotic pressure or tonicity Electrolytes imbalance, Acid-base balance, Na+-K+ pump ADH & Renal function, Body homeostasis etc.:

Body weight, Period of fasting Daily loss, Loss due to Preexisting condition/disease % of Dehydration + Loss during operation Composition of fluid, Redistribution of fluid, Molarity, Molality, Molecular wt. Effective osmotic pressure or tonicity Electrolytes imbalance, Acid-base balance, Na+-K+ pump ADH & Renal function, Body homeostasis etc. Factors should be considered during infusion/transfusion

Basic Concepts:

Basic Concepts

Basic Definitions:

Basic Definitions Osmosis It is the movement of solvent molecules across a membrane into a region in which there is a higher concentration of the solutes

Basic Definitions:

Basic Definitions Osmotic Pressure It is the pressure that must be applied to the side with more solute to prevent net movement Os P

Basic Definitions:

Basic Definitions Oncotic Pressure/ Tonicity: Effective osmotic pressure of a solution relative to that of plasma. Onc P

Basic Definitions:

Basic Definitions One Osmole Equal to molecular weight in grams (one mole) of non dissociable substances X number of freely moving particles which each molecule liberate in solution 180 gm glucose in 1 liter = 1mmol/L = 1 Osmole/ L Highly ionisable substances: 58.5 gm Nacl in 1liter =1 mmol/L = 2 Osmole/L

Basic Definitions:

Basic Definitions Osmolality (NOT AFFECTED BY THE VOLUME OF SOLUTES IN SOLUTION) Number of osmoles per unit of total weight of solvent ( mOsm/kg H 2 O ) Osmolality = Na + x 2 (mmol/l) + glucose (mmol/l) + BUN (mmol/l) 290 mOsm/kg Osmolarity Number of osmoles per unit of total volume of solvent ( mOsm/ l H 2 O ) mOsm/kg = mOsm/ L Plasma Osmolality = 280 - 310 mOsm/kg Plasma Osmolarity = 280 - 310 mOsm/l

Basic Definitions:

Basic Definitions Tonicity Osmolality Physiological term (effective Os P relative to plasma) Solutes that do not cross the cell membrane only counts Chemical term All solutes contributes to Osmolality 2 x Na + + Glucose 285 mOsm/kg Na + x 2 + glucose + BUN 290 mOsm/kg Oncotic Pressure = Osmolality x19.3 (mmHg/Osm/kg)

(mgm % X 10)/MW = mmol/L :

(mgm % X 10)/MW = mmol/L 0.9% Nacl (900 X 10) / (23 + 35.5) = 154 mmol/l

Compartmental Distribution of Total Body Water:

Compartmental Distribution of Total Body Water

Body Fluid Compartments:

Body Fluid Compartments

Compartmental Distribution of Total Body Water :

Compartmental Distribution of Total Body Water Plasma 3L Interstitial fluid 11L Intracellular fluid 28L 66% ICF 33% ECF Total body water 70 kg male TBW 42 L

Water Homeostasis:

Water Homeostasis Ingested fluids 1300 Solid food 800 Metabolic water 400 Skin 500 Lungs 400 Urine 1500 Faeces 100 ICF ECF Water Homeostasis

Solute Composition of Body Fluid Compartments:

Solute Composition of Body Fluid Compartments Solutes Na + 10 HPO 4 - K + 150 SO 4 -- 150 Mg ++ 4 HCO 3 - Prot Water Solutes Na + 140 Cl - 114 K + 4 HCO 3 - 30 Water ICF ECF 280 - 310 mOsm/l

Intravenous Fluids:

Intravenous Fluids

Recommended Approach to Perioperative Fluid Management:

Recommended Approach to Perioperative Fluid Management

Practical Fluid Balance:

Practical Fluid Balance Na + Na + Na + Na + Na + Na + Rule 1 All infused Na + can not gain access to the ICF Because of the Sodium Pump ECF ICF Isotonic = NO Water Exchange

Practical Fluid Balance:

Practical Fluid Balance H 2 O H 2 O H 2 O Rule 2 Water without Na expands the TBW (enter both ICF & ECF in proportion to their initial volume) ECF ICF

PowerPoint Presentation:

Hypotonic = Water Exchange a. Hypotonic saline (¼ NS) H 2 O Rule 3 Change in tonicity of Na solutions (relative to Plasma) causes water exchange

PowerPoint Presentation:

Hypertonic = water exchange Increase Plasma Volume (x times ) the originally infused amount from IFV & ICF b. Hypertonic solution H 2 O

Compartmental Expansion:

Compartmental Expansion Changes in Volume (ml) (1 liter) ECF ICF Remarks Saline 0.9% + 1000 0 Na + remains in ECF Glucose 5% +333 +666 66% of TBW is ICF Saline 0.45% +666 +333 33% of TBW is ECF

PowerPoint Presentation:

Glucose 5% 500ml = 7000 X 3 / 42 0.9% Saline 500 ml = 2000 X 3 / 14 Change in plasma volume = volume infused x PV/Vd

Electrolyte contents (Commonly used IV fluids):

Electrolyte contents (Commonly used IV fluids) Solution Electrolyte contents (mEq /l) * g/L R/Plasma Osmolarity (mOsmol.L -1 ) Na + Cl _ K + Ca 2+ Glucose* Lactate Dextrose 5% (D 5 W) 50 **Hypotonic 280 ½ NS 77 77 Hypotonic 154 Lactated Ringer 130 109 4 3 28 !! Isotonic 273 HS 131 112 5 4 29 Isotonic 281 N saline 154 154 Isotonic 308 D 5 ¼ NS 38.5 38.5 50 !! Isotonic 335 D 5 ½ NS 77 77 50 !! Hypertonic 432 3% S 513 513 Hypertonic 1026

Crystalloids:

Crystalloids True solution, No particulate Expands IVC adequately (less than colloids), however Small increase in plasma volume Replenishes interstitial compartment It leaves IVC faster ( t / 2 20-30 minutes) Cheap Increase GFR No risk of allergic reaction

Dynamics of IV Fluids:

Dynamics of IV Fluids Water solution Intracellularly All hypotonic solutions e.g. 5% dextrose called as maintenance type of fluids Electrolyte solutions Interstitial compartment Isotonic Called replacement type of fluid

Crystalloids ( Lactated Ringer Solution ):

Crystalloids ( Lactated Ringer Solution ) Isotonic losses replacement ( though slightly Hypotonic ) Least effect on ECF, Most physiological when large volume needed Lactate is converted to bicarbonate Tend to lower serum Na +

Crystalloids ( Normal Saline ):

Crystalloids ( Normal Saline ) Large volumes produce dilutional Hyperchloremic acidosis High Na + & Cl – content (154 mEq/L) Plasma bicarbonate decreases as chloride concentration increases Preferred in Hypochloremic metabolic acidosis Dilution of PRBCs

Crystalloids ( 5% Dextrose in Water D5W):

Crystalloids ( 5% Dextrose in Water D5W) H 2 O H 2 O H 2 O Glucose is metabolized Pure water deficits Maintenance of fluids in patients on sodium Restriction C/I in neurosurgical Procedures

PowerPoint Presentation:

Hypertonic Saline 3% and 7.5% Increase Plasma Volume from IFV & ICF Small Volume Resuscitation Crystalloids ( Hypertonic Saline) H 2 O Estimate 750 ml 250 ml

PowerPoint Presentation:

Suspension of particle rather than a solution High Molecular Weight: Unable to pass through semi permeable membrane Remains confined to intra-vascular compartment (at least initially) Do not correct water and electrolyte deficiencies Colloids

PowerPoint Presentation:

colloids Colloids Most logical choice for intravascular expansion Since greater portion remains in IVC & for longer time ( t /2 3-6 hours) Less volume is required & initial resuscitation is rapid 500 ml of colloids expands plasma by 500 x 3/3 = 500ml

PowerPoint Presentation:

Do not correct water and electrolyte deficiencies Antigenicity & Anaphylactic Reaction Blood typing Coagulopathy Never exceed 1 – 1.5 liter/day (20 ml/kg/day) Colloids

PowerPoint Presentation:

Blood-derived: Albumin 5%( Heated, Antigenic, hypotensive) Dextran: Dextran 70, Dextran 40 (microcirculation), Dextran 1 Gelfusine ( Anaphylaxis ) Hydroxy ethyl starch Hetastarch 6% MW = 450 000 Effective Plasma Expander Serum Amylase Least Antigenicity &Effect on Coagulation Colloids (Types)

Blood & Blood by- products:

Blood & Blood by- products Whole blood Packed red blood cells (PRBCs) Leukocytes depleted blood Fresh frozen plasma Platelets Factors Freeze dried factor VII (infection) Cryoprecipitate (VIII) antihemophilic Christmas (IX) concentrate

PowerPoint Presentation:

% Dehydration + Pre-existing fluid loss + Loss during surgery The goal is to maintain the effective circulatory volume while avoiding interstitial fluid overload whenever possible. Summary

PowerPoint Presentation:

Crystalloids, when given in sufficient amount, can be just as effective as colloids in restoring intravascular volume Replacing an intravascular volume deficit with crystalloids generally requires three to four times the volume needed when using colloids Cont…

PowerPoint Presentation:

Most surgical patients have an extra cellular fluid deficit that exceeds the intravascular deficit Severe intravascular fluid deficit can be more rapidly corrected by colloid solutions The rapid administration of large amounts of crystalloids (>4-5L) is more frequently associated with significant tissue edema. Cont…

PowerPoint Presentation:

Some evidence suggests – but does not prove – that marked tissue edema can impair Oxygen transport, Tissue healing and Return of bowel function following major surgery. Cont…

Volume Effect of Crystalloids:

Volume Effect of Crystalloids

PowerPoint Presentation:

Typically occurs only after the infusion of more than 3 l of normal saline Carrier Solutions

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Why do we need colloids?

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B. COLLOIDS

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THANK YOU

PowerPoint Presentation:

It includes – i) Supplying basic maintenance requirement ii) Replacing preoperative deficit iii) Intra-operative loss (blood + fluid redistribution + evaporation) Selection of fluid depends on surgical procedure & expected blood loss. Maintenance fluid can be use when surgical procedure involves minimum blood loss & fluid shift. For other procedure Lactate Ringers solution is generally used. Intra-operative fluid replacement:

Blood Replacement Therapy:

Blood Replacement Therapy

PowerPoint Presentation:

Ideally blood loss should be replaced by crystalloid or colloid solution to maintain intravascular volume; untill danger of amaemia outweighes the risk of transfusion. At this point further blood loss is replaced by transfusion of red cell (packed cell). For most pt. this point corresponds to a haemoglobin between 7-8 gm/dl or haematocret 21-24%. 10 gm/dl haemoglobin level is optimal in most of the case. Below 7 gm/dl cardiac output is increased to maintain O 2 delivery to the tissue . Cont….

PowerPoint Presentation:

Most clinician use Hartmann sol n 3-4 times the volume of blood loss or colloid 1:1 ratio; until the transfusion point is reached. At that time blood is replaced “unit for unit” as it is lost. Transfusion point can be estimated by preoperative haematocret & estimated blood volume. Pt. with normal haematocrit should be transfused only after loss greater than 10-20% (15%) of the blood volume. Transfusion are not recommended until the Hct reduced to 30% or Hb 8gm/dl. Cont….

Average Blood Volumes:

Average Blood Volumes Age Blood volume Neonates Premature 95mL/kg Full term 85mL/kg Infants 80mL/kg Adults Men 75mL/kg Women 65mL/kg

Patients with normal HCT should only be transfused after 10-20% loss of blood volume:

Patients with normal HCT should only be transfused after 10-20% loss of blood volume One unit of blood Increases Hb by 1 gm/dl Or HCT by 2-3% 10 ml pack red cells/kg Increases Hb by 3gm/dl Or HCT by 10% Useful guide Line:

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THANK YOU

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Thank You

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