objectives• Normal fluid physiology• Water /electrolyte regulation• Periop fluid assessment &requirement• Third space losses• Blood loss &replacement• Iv fluids comp., blood & blood components• Transfusion therapy

Total Body Water (TBW)• Varies with age, gender, body habitus• 55% body weight in males• 45% body weight in females• 80% body weight in infants• Less in obese: fat contains little water

60% fluids

55% fluids

Total Body MassTotal Body Mass

female

male

45% solids

40% solids

2/3 Intra-

cellular fluid (ICF)

1/3 (ECF) 80%

20%

Interstitial fluid

Plasma

• Some fluid is lost from blood in the Some fluid is lost from blood in the interstitial tissues, and returned by the interstitial tissues, and returned by the lymphatic systemlymphatic system

(also lymph and other miscellaneous fluids)

Fluid and Electrolyte Regulation• Volume Regulation

- Arginine-Vasopressin (Antidiuretic Hormone)- Renin/angiotensin/aldosterone system- Baroreceptors in carotid arteries and aorta- Stretch receptors in atrium and juxtaglomerular aparatus- Cortisol

Regulation of ECF

Electrolyte Regulation• Plasma Osmolality Regulation

- Arginine-Vasopressin (ADH)- Central and Peripheral osmoreceptors

• Sodium Concentration Regulation- Renin/angiotensin/aldosterone system- Macula Densa of JG apparatus

Hormonal regulation

• Daily water intake must equal water outputDaily water intake must equal water outputWater IntakeWater Intake Water OutputWater Output

• Stimulated by Stimulated by thirst center of thirst center of hypothalamushypothalamus

• OsmoreceptorsOsmoreceptors detect an detect an increase in increase in fluid fluid osmolarityosmolarity

• Thirst center inhibited by Thirst center inhibited by distension of stomach distension of stomach wallwall

• SensibleSensible loss: loss: urine, feces, urine, feces, noticible sweatnoticible sweat

• InsensibleInsensible loss: loss: respiration and respiration and non-noticible non-noticible sweatsweat

• Urine output is the primary Urine output is the primary regulator of water out (ADH from regulator of water out (ADH from posterior pituitary gland)posterior pituitary gland)

Normal Fluid Balance• Daily adult water intake = 2600 cc

• 1400 cc liquid• 800 cc in solid food• 400 cc from metabolism

• Normally intake = loss• 1500 cc urine• 400 cc respiration• 500 cc evaporation• 200 cc stool

• Insensible losses increased by fever, perspiration, low humidity

• Measurable losses increased by diuretics, bowel preps, etc

Preoperative Evaluationof Fluid Status

• Factors to Assess:- mental status- h/o intake and output- blood pressure: supine and standing- heart rate- skin turgor- urinary output- serum electrolytes/osmolarity

Degree of DehydrationClinical SignsClinical Signs MildMild Moderate Moderate SevereSevere

↓ ↓ in body weightin body weight 3-5%3-5% 6-10%6-10% 11-15%11-15%

Fontenelle/Skin Fontenelle/Skin turgor/Eyesturgor/Eyes

Normal (+/-)Normal (+/-) ↓↓ ↓↓↓↓

Skin ColorSkin Color NormalNormal PalePale GreyGrey

Mucus MembranesMucus Membranes Normal to DryNormal to Dry DryDry ParchedParched

Cap RefillCap Refill 2-3 seconds2-3 seconds 3-4 seconds3-4 seconds > 4 seconds> 4 seconds

Heart RateHeart Rate NormalNormal ↑↑ ↑↑↑↑

Blood PressureBlood Pressure NormalNormal Postural changesPostural changes HypotensionHypotension

Urine OutputUrine Output Normal to slight Normal to slight ↓↓ OliguriaOliguria Severe oliguria or Severe oliguria or anuriaanuria

TearsTears ↓↓ ↓↓ ↓↓ to absentto absent AbsentAbsent

Urine Spec GravUrine Spec Grav >1.020>1.020 ↑↑↑↑ ↑↑↑ ↑↑↑ or anuriaor anuria

Orthostatic Hypotension• Systolic blood pressure decrease of greater than

20mmHg from supine to standing• Indicates fluid deficit of 6-8% body weight

- Heart rate should increase as a compensatory measure- If no increase in heart rate, may indicate autonomic

dysfunction or antihypertensive drug therapy

CLINICAL CORRELATIONClinical correlation (Severity of shock)

% of Blood lost

(For a 70 Kg (Adult

Blood Required

 1.       Shock absent (covert shock): PR = 60-100/min BP=110-140;AAbsent vasoconstriction(VC);UUrine output (UO) = 40 – 50 ml/hr. 

 <10%-15%

 <750 ml 

 No blood required

2.       Compensated Shock: PR = 100-120/minBP = 110-140;VC = +; UO =30-40 ml/hr. 

10% - 30% 750ml—11/2L ½ L – L

 3.       Early decompensation: PR = 120-140BBP = 70-110; VC = ++;UO = <30ml/hr 

 30 – 50%

 1 ½ l – 2 ½ L

 1

4.       Severe decompensation: PR =>140/minBP = 0-70; VC = +++; UO = Zero 

> 50% 2 ½ - 3 ½ > 3L

Intravenous Fluids:• Conventional Crystalloids• Colloids• Hypertonic Solutions• Blood/blood products and blood substitutes

Crystalloids• Combination of water and electrolytes

- Balanced salt solution: electrolyte composition and osmolality similar to plasma; example: lactated Ringer’s, Plasmlyte, Normosol.

- Hypotonic salt solution: electrolyte composition lower than that of plasma; example: D5W.

Colloids• Fluids containing molecules sufficiently large enough to

prevent transfer across capillary membranes.• Solutions stay in the space into which they are infused.• Examples: hetastarch (Hespan), albumin, dextran.

SolutionSolutionss

VolumeVolumess NaNa++ KK++ CaCa22++ MgMg22++ ClCl-- HCOHCO33

-- DextroseDextrose buffers mOsm/LmOsm/L

ECFECF 142 4 5 103 27 280-310Lactated Lactated Ringer’sRinger’s 130 4 3 109 Lactate28 273

0.9%0.9% NaClNaCl 154 154 308

0.45%0.45% NaClNaCl 77 77 154

D5WD5W 50 278

Normosol 140 5 3 98 Acetate27295

plasmalplasmalyteyte 140 5 3 98

Gluconate 23

295

D5/0.45D5/0.45% NaCl% NaCl 77 77 50 406

3%3% NaClNaCl 513 513 10266%6%

HetastarHetastarchch

500 154 154 310

25%25% , ,5%5% AlbuminAlbumin 250,500

130-

160<2.5

130-160 330

Common parenteral fluid therapyCommon parenteral fluid therapy

Infusion of IV FluidsVolumetric Effects (1000ml)

Intracellular Interstitial Intravascular

Dext 5% 666 250 84ml

RL 100 700 200ml

N/S - 825 275ml

5% Albumn + N/S

- - 1000ml

Pentastarch 1500ml

ISOTONIC SOLUTIONS • 0.9% Normal Saline

• D5W 5 % Dextrose*

• D51/4NS 5% Dextrose 0.2% NS

• D51/3NS 5% Dextrose 0.3% NS • LR or RL Lactated Ringers Solution

HYPERTONIC SOLUTIONS• 3% N S 3% Normal saline• 5 % N S 5% Normal Saline• D 10 W Dextrose 10% in water• D 20 W Dextrose 20% in Water• D5 ½ NS 5%Dextrose,with 0.45% Normal Saline• D5NS 5% Dextrose with 0.9% Normal Saline• D5LR 5% Dextrose with Lactated Ringers

HYPOTONIC SOLUTIONS

• 1/3 N S 0.33% Normal Saline

• 1/2 N S 0.45% Normal Saline

• D 2.5 W Dextrose 2.5% in water

Perioperative Fluid Requirements• The following factors must be taken into account:• Maintenance fluid requirements• NPO and other deficits: NG suction, bowel prep• Third space losses• Replacement of blood loss• Special additional losses

Maintenance Fluid Requirements• Insensible losses such as evaporation of water from

respiratory tract, sweat, feces, urinary excretion. Occurs continually.

• Adults: approximately 1.5 ml/kg/hr• “4-2-1 Rule”

- 4 ml/kg/hr for the first 10 kg of body weight- 2 ml/kg/hr for the second 10 kg body weight- 1 ml/kg/hr subsequent kg body weight- Extra fluid for fever, tracheotomy, denuded surfaces

NPO and other deficits• NPO deficit = number of hours NPO x maintenance fluid

requirement.• Bowel prep may result in up to 1 L fluid loss.• Measurable fluid losses, e.g. NG suctioning, vomiting,

ostomy output.

Third Space Losses• Isotonic transfer of ECF from functional body fluid

compartments to non-functional compartments.• Depends on location and duration of surgical procedure,

amount of tissue trauma, ambient temperature, room ventilation.

Replacing Third Space Losses

• Superficial surgical trauma: 1-2 ml/kg/hr• Minimal Surgical Trauma: 3-4 ml/kg/hr

- head and neck, hernia, knee surgery• Moderate Surgical Trauma: 5-6 ml/kg/hr

- hysterectomy, chest surgery• Severe surgical trauma: 8-10 ml/kg/hr (or more)

- AAA repair, nehprectomy

Blood Loss• Replace 3 cc of crystalloid solution per cc of blood loss

(crystalloid solutions leave the intravascular space)• When using blood products or colloids replace blood loss

volume per volume

Blood Loss Estimation During Surgery• Amount of blood in suction• Small gauze sponge (ray-tec) 25cc• Laparatomy sponge 125-150cc• Weigh sponges• ? Serial hematocrits• Based on known average case blood loss

Other factors• Ongoing fluid losses from other sites:

- gastric drainage- ostomy output- diarrhea

• Replace volume per volume with crystalloid solutions

Example• 50 y/o male, 70 kg, for hemicolectomy• NPO after midnight, surgery at 0800, received bowel

prep• 4 hr. procedure, 500 cc blood loss• What are his estimated intraoperative fluid requirements?

Example (cont.)

• Fluid deficit: 1.5 ml/kg/hr x 8 hrs = 840 ml + 1000 ml for bowel prep = 1840 ml total deficit

• Maintenance: 1.5 ml/kg/hr x 4hrs = 420mls• Third Space Losses: 6 ml/kg/hr x 4hrs =1680 mls• Blood Loss: 500ml x 3 = 1500ml• Total = 1840+420+1680+1500=5440mls

Clinical Evaluation of Fluid Replacement

1. Urine Output: at least 1.0 ml/kg/hr2. Vital Signs: BP and HR normal (How is the patient doing?)3. Physical Assessment: Skin and mucous membranes no dry;

no thirst in an awake patient4. Invasive monitoring; CVP or PCWP may be used as a

guide5. Laboratory tests: periodic monitoring of hemoglobin and

hematocrit

SPECIFIC GRAVITY OSMOLALITY1.000 01.005 1751.010 3501.015 5 251.020 7001.025 8751.030 1050

Hyponatremia• TBW may be high, normal, or low• 1% postoperative patients• Very common in HIV hospitalized patients• Results in reduced plasma osmolality• Clinical features:

• <125 mental status changes, muscle cramps, lethargy, nausea, anorexia

• <115 seizures and cardiovascular collapse

Hyponatremia Treatment• Acute normalization not recommended because of risk of

cerebral edema, seizures• Hypervolemic: (renal failure, CHF, cirrhosis, nephrotic

syndrome): water restriction, diuretics• Hypovolemic(diuretics, vomiting, diarrhea, adrenal insufficiency,

bowel prep): normal saline, or if severe judicious use of hypertonic saline

• Normovolemic (SIADH, hypothyroidism, drugs): fluid restriction

Hypernatremia:• Again, TBW may be high, normal, or low• With the exceptions of small bowel secretions and pancreatic

secretions, loss of body fluids results in hypernatremia• Tremulousness, mental confusion, weakness, seizures, coma• Rapid correction can induce cerebral edema• Correction formula:

• Normal [Na}/measured [Na]xTBW = current TBW• Water deficit = TBW - current TBW

Hypernatramia(cont.)• Hypervolemic(mineralocorticoid excess): Na removed with

diuretics, dialysis; water replaced with D5W• Normovolemic(diabetes insipidus): treat etiology, correct free

water deficit with D5W, exogenous vasopressin• Hypovolemic (diarrhea, vomiting osmotic diuretics, impaired

thirst): volume ressusitate with balanced salt solution, then replace water deficit with D5W

Hypokalemia• Serum [K] < 3.3 meq/l• Total body K deficit• Shift in extracellular to intracellular K• [K] poor index of total body K• 70 kg man, drop from [K] 4 to 3meq/l reflects deficit of 100 -200

meq K • K loss from GI tract, kidney(diuretics, steroids, RTA)• Rapid shift with alkalosis

Hypokalemia• Clinical features:

• Weakness, Cardiac dysrhythmias, Augmentation neuromuscular block

• Treatment: Maximum IV infusion rate: 1 mEq/kg/hr• Marked hypokalemia:

• Monitor serum K closely• 0.5-1 mEq/kg/dose given as an infusion for 1-2 hour • Dysrhythmias can be treated with K 0.5-1.0 meq/5 mins

HyperkalemiaCauses

• Decreased excretion (renal failure, hypoaldosteronsim)

• Massive tissue injury (crush, burns)• Intracellular to extracellular shift (acidosis,

succinylcholine)• Administration of blood products• Hemolyzed sample

Hyperkalemia

• Clinical features: • Muscle weakness, • Paresthesias, • Cardiac dysrhythmias, • Peaked T-waves, bradycardia, wide QRS, prolonged

QT, VT, VF

Hyperkalemia Treatment• CaCl for EKG changes• Hyperventilation• Blood alkalinisation : Na-Bicarbonate• Glucose and insulin (10U reg insulin for each 25g

glucose)• Cation exchange resins (Kayexalate), • dialysis for slower correction

Hypercalcemia• Hyperparathyroidism, malignancy, immobilization,

granulomatous disease• GI symptoms, mental status changes, polyuria, hypertension• Prolonged PR, prolonged QT• Unpredictable effect on muscle relaxants• Careful positioning

• Remove/treat 1 cause• Rehydration – 4 – 6l• Biphosphonates (pamidronate 90mg over 4 hrs)• Forced diuresis (saline + furosemide)• Glucocorticoids (prednisone 40mg/d)• Calcitonin• Haemodialysis

Management

Hypocalcemia• [Ca} < 8.5 mg/dl• Parathyroidectomy, radiation therapy, vit D deficiency,

malapsorption• Neuromuscular irritability, circumoral numbness, stridor,

laryngospasm, tetany, apnea, seizures, shock• Anesthetic considerations: aggrevated by alkalosis, rapid blood

transfusions, hypothermia, renal dysfunction• Monitor coagulation

• Hypocalcaemia• Identify cause (and treat)• Vitamin D (when indicated)• Calcium gluconate – IV/IM• Calcium chloride• Oral calcium supplements• I - hydroxychole calciferol• Diet dairy products

Management

• Mainly an intracellular ion• Concentration : 0.7 – 0.9 Mmol/L• A co-factor in many biochemical reactionsHypomagnesaemia (<0.7 Mmol/L• May be due to:-

• Excessive use of diuretics• Administration of insulin in D/ketoacidosis• Large GIT fluid loses• Long term parenteral nutrition without supplimentation

MAGNESIUM

• Oral magnesium hydroxide (poorly absorbed)• Im magnesium chloride• Slow IV magnesium sulphate (30-50 Mmol/12 – 24 hrs,

then 15 – 20 Mmol/day

Treatment

• Due to:• Excessive mgt+ administration• Renal failure

Treatment• Remove cause• IV calcium chloride (emergency)• Haemodialysis/haemofiltration

Hypermagnesaemia (> 0.9 Mmol/L)

Transfusion Therapy

• 22 million blood components administered annually in U.S.- (pRBC’s, whole blood, fresh frozen plasma, platelets,

etc.) .• 12,000,000 units of pRBC’s annually

- 60% of transfusions occur perioperatively.- responsibility of transfusing perioperatively is with

the anesthesiologist.

When is Transfusion Necessary?• “Transfusion Trigger”: Hgb level at which

transfusion should be given.- Varies with patients and procedures

• Tolerance of acute anemia depends on:- Maintenance of intravascular volume- Ability to increase cardiac output- Increases in 2,3-DPG to deliver more of the carried

oxygen to tissues

Oxygen Delivery

• Oxygen Delivery (DO2) is the oxygen that is delivered to the tissues

• DO2= Cardiac Output (CO) x Oxygen Content (CaO2)• Cardiac Output (CO) = HR x SV • Oxygen Content (CaO2):

- (Hgb x 1.39)O2 saturation + PaO2(0.003)- Hgb is the main determinant of oxygen content in the blood

Oxygen Delivery (cont.)

• Therefore: DO2 = HR x SV x CaO2

• If HR or SV are unable to compensate, Hgb is the major determinant factor in O2 delivery

• Healthy patients have excellent compensatory mechanisms and can tolerate Hgb levels of 7 gm/dL.

• Compromised patients may require Hgb levels above 10 gm/dL.

Blood Groups

Antigen on Plasma IncidenceBlood Group erythrocyte Antibodies White African-

AmericansA A Anti-B 40% 27%B B Anti-A 11 20AB AB None 4 4O None Anti-A 45 49

Anti-BRh Rh 42 17

Cross Match• Major:

- Donor’s erythrocytes incubated with recipients plasma• Minor:

- Donor’s plasma incubated with recipients erythrocytes• Agglutination:

- Occurs if either is incompatible• Type Specific:

- Only ABO-Rh determined; chance of hemolytic reaction is 1:1000 with TS blood

Type and Screen• Donated blood that has been tested for ABO/Rh antigens

and screened for common antibodies (not mixed with recipient blood).- Used when usage of blood is unlikely, but needs to be

available (hysterectomy).- Allows blood to available for other patients.- Chance of hemolytic reaction: 1:10,000.

Component Therapy

• A unit of whole blood is divided into components; Allows prolonged storage and specific treatment of underlying problem with increased efficiency:

- packed red blood cells (pRBC’s)- platelet concentrate- fresh frozen plasma (contains all clotting factors)- cryoprecipitate (contains factors VIII and fibrinogen; used in Von

Willebrand’s disease)- albumin - plasma protein fraction- leukocyte poor blood - factor VIII- antibody concentrates

Packed Red Blood Cells

• 1 unit = 250 ml. Hct. = 70-80%.• 1 unit pRBC’s raises Hgb 1 gm/dL.• Patient hemoglobin levels down to 7 gm/dL are

generally tolerated if intravascular volume is maintained.

• Mixed with saline: LR has Calcium which may cause clotting if mixed with pRBC’s.

Platelet Concentrate• Treatment of thrombocytopenia• Intraoperatively used if platlet count drops below 50,000 cells-

mm3 (lab analysis).• 1 unit of platelets increases platelet count 5000-10000 cells-mm3.

• Risks:- Sensitization due to HLA on platelets

- Viral transmission

Fresh Frozen Plasma

• Plasma from whole blood frozen within 6 hours of collection.

- Contains coagulation factors except platelets- Used for treatment of isolated factor deficiences, reversal of

Coumadin effect, TTP, etc.- Used when PT and PTT are >1.5 normal

• Risks:- Viral transmission- Allergy

Complications of Blood Therapy• Transfusion Reactions:

- Febrile; most common, usually controlled by slowing infusion and giving antipyretics

- Allergic; increased body temp., pruritis, urticaria. Rx: antihistamine,discontinuation. Examination of plasma and urine for free hemoglobin helps rule out hemolytic reactions.

Complications of Blood Therapy (cont.)

• Hemolytic: - Wrong blood type administered (oops).- Activation of complement system leads to intravascular

hemolysis, spontaneous hemorrhage.- Signs: hypotension,fever, chills, dyspnea, skin flushing,

substernal pain. Signs are easily masked by general anesthesia.- Free Hgb in plasma or urine - Acute renal failure- Disseminated Intravascular Coagulation (DIC)

Treatment of Acute Hemolytic Reactions

• Immediate discontinuation of blood products• Maintenance of urine output with crystalloid

infusions• Administration of mannitol or Furosemide for

diuretic effect

Complications (cont.)• Transmission of Viral Diseases:

- Hepatitis C; 1:30,000 per unit- Hepatitis B; 1:200,000 per unit- HIV; 1:450,000-1:600,000 per unit- 22 day window for HIV infection and test detection- CMV may be the most common agent transmitted, but

only effects immunocompromised patients- Parasitic and bacterial transmission very low

Other Complications

- Decreased 2,3-DPG with storage: ? Significance- Citrate: metabolism to bicarbonate; Calcium binding- Microaggregates (platelets, leukocytes): micropore

filters controversial- Hypothermia: warmers used to prevent- Coagulation disorders: massive transfusion (>10 units)

may lead to dilution of platelets and factor V and VIII.- DIC: uncontrolled activation of coagulation system

Autologous Blood• Pre-donation of patient’s own blood prior to

elective surgery• 1 unit donated every 4 days (up to 3 units)• Last unit donated at least 72 hrs prior to surgery• Reduces chance of hemolytic reactions and

transmission of blood-bourne diseases• Not desirable for compromised patients

Administering Blood Products

- Consent necessary for elective transfusion- Unit is checked by 2 people for Unit #, patient ID,

expiration date, physical appearance.- pRBC’s are mixed with saline solution (not LR)- Products are warmed mechanically and given slowly if

condition permits- Close observation of patient for signs of complications- If complications suspected, infusion discontinued,

blood bank notified, proper steps taken.

Alternatives to Blood Products

• Autotransfusion• Blood substitutes

Autotransfusion

• Commonly known as “Cell-saver”• Allows collection of blood during surgery for re-

administration• RBC’s centrifuged from plasma• Effective when > 1000ml are collected

Blood Substitutes• Experimental oxygen-carrying solutions: developed to

decrease dependence on human blood products• Military battlefield usage initial goal• Multiple approaches:

- Outdated human Hgb reconstituted in solution- Genetically engineered/bovine Hgb in solution- Liposome-encapsulated Hgb - Perflurocarbons

Blood Substitutes (cont.)

• Potential Advantages:- No cross-match requirements- Long-term shelf storage- No blood-bourne transmission- Rapid restoration of oxygen delivery in traumatized

patients- Easy access to product (available on ambulances, field

hospitals, hospital ships)

Blood Substitutes (cont.)• Potential Disadvantages:

- Undesirable hemodynamic effects:• Mean arterial pressure and pulmonary artery pressure increases

- Short half-life in bloodstream (24 hrs)- Still in clinical trials, unproven efficacy- High cost

Transfusion Therapy Summary• Decision to transfuse involves many factors• Availability of component factors allows treatment of

specific deficiency• Risks of transfusion must be understood and explained to

patients• Vigilance necessary when transfusing any blood product