3. Fluid Electrolyte in Anesthesia

1

Algemene Principes van Vochtbeleid

M. Verhaegen,Hasanul ArifinAnesthesiologyUZ KU Leuven

2

Intraoperative IV Fluid Therapy: Historical Perspective (1)

Fluid restriction Postoperative Salt Intolerance

(Coller et al, Ann Surg 1944, 119: 533-541) “No isotonic saline solution or Ringer’s solution

should be given during the day of operation and during the subsequent first two postoperative days”

3

Intraoperative IV Fluid Therapy: Historical Perspective (2)

Trauma/surgery: large fluid deficits Acute Changes in Extracellular Fluid

Associated with Major Surgical Procedures(Shires et al., Ann Surg 1961, 154: 803-810) Major surgery is associated with significant

functional extracellular fluid volume deficits Replace with large volumes of balanced

electrolyte solutions

Artificiële colloïden en indicaties albumine Bloedproducten Hemodilutie en autotransfusie Electrolietenafwijkingen Het zuur-base evenwicht Vochtbeleid

Vochtcompartimenten Distributie van water over de vochtcompartimenten Electrolieten samenstelling

Het perioperatieve vochtbeleid

Body Fluid Compartments

Total body water = 60 % of body weight (BW)

2/3

Intracellular water= 40 % of BW

1/3

Extracellular water

= 20 % of BW

Plasma (5 % of BW)

Extracellular water

= 20 % of BW

% of body weight

70 kg male (L)

Total body water

60 42

Intracellular 40 28

Extracellular 20 14

Intravascular

5 3.5

Interstitial 15 10.5Sendak in Principles and Practice of Anesthesiology (2nd ed), Longnecker et al.,

7

Extracellular Extravascular Water

Interstitial fluid and lymph Rapid exchange (with plasma) Slow exchange

Bone water «Cavitary» fluids: transudates of plasma

E.g. peritoneal, pericardial, pleural Transcellular fluids: active transport mechanisms

E.g. salivary, hepatic, biliary, pancreatic, gastrointestinal intraluminal, mucosal, dermal, intraocular, intrathecal

Age- and Gender-related Changes in Total Body Water

Total body water (%)

Age Male Female

1 mo 76 76

1 – 12 mo 65 65

1 – 10 yr 62 62

10 – 16 yr 59 57

17 – 39 yr 61 50

40 – 59 yr 55 47

> 60 yr 52 46Hays: Dynamics of body water and electrolytes (1980)In: Maxwell et al (eds): Clinical disorders of fluid and electrolyte metabolism

Relationship Between Body Habitus and Total Body Water in Adults

Total body water (%)

Build Male Female

Thin 65 55

Average 60 50

Obese 55 45Principles and Practice of Anesthesiology (2nd ed), Longnecker et al.

10

Electrolytes:Physiologic and Chemical Activity

Number of particles/unit volume (m)moles / liter of solution

Number of osmotically active particles/unit volume (m)osmoles / liter of solution

Number of electric charges/unit volume (m)equivalents / liter of solution

11

Body Fluids: Ionic Composition

Electrical neutrality In any fluid compartment or intravenous

solution the number of milliequivalents of cations is balanced by precisely the same number of milliequivalents of anions

Chemical combining activity (milliequivalents) 1 equivalent of an anion is the amount

which can combine with 1 g of hydrogen

Body Fluid Compartments: Composition

Intracellular Extracellular

Intravascular Interstitial

Sodium (mEq/l) 10 145 142

Potassium (mEq/l) 140 4 4

Calcium (mEq/l) <1 3 3

Magnesium (mEq/l) 50 2 2

Chloride (mEq/l) 4 105 110

Bicarbonate (mEq/l) 10 24 28

Phosphorus (mEq/l) 75 2 2

Protein (g/dl) 16 7 2

Body Fluid Compartments: CompositionElectrolyte Plasma

(mEq/L)

Plasma water (mEq/L)

Interstitial fluid (mEq/L)

Intracell. fluid (mEq/kg

H2O)

CATIONS

Sodium 142 152 145 10

Potassium 4 4 4 156

Calcium 5 5 3 3

Magnesium 3 3 1 26

Total 154 164 153 195

ANIONS

Chloride 103 109 114 2

Bicarbonate 27 29 30 10

Phosphate 2 2 2 108

Sulfate 1 1 1 20

Organic acids

5 6 5

Protein 16 17 1 55

Total 154 164 153 195

Gibbs - Donnan Principle

Equilibrium

1A 2A 1B 2B

5 Pr-

5 Na+

10 Cl-

10 Na+

5 Pr-

5 Na+

4 Cl-

4 Na+

6 Cl-

6 Na+

•Na+1B x Cl-

1B = Na+2B x Cl-

2B

•Electrical neutrality

Non-diffusible protein anions

Plasma water (mEq/l)

Interstitial fluid (mEq/L)

CATIONS

Sodium 152 145

Potassium 4 4

Calcium 5 3

Magnesium 3 1

Total 164 153

ANIONS

Chloride 109 114

Bicarbonate 29 30

Phosphate 2 2

Sulfate 1 1

Organic acids 6 5

Protein (org. anions) 17 1

Total 164 153

141 147

16

Water Distribution and Movement

Hydrostatic forces Mechanical pressure generated by the heart Weight of blood within the vasculature

Osmotic forces The movement of water is governed by the

compartmental concentrations of osmotically active substances, predominantly electrolytes

Extracellular: sodium, chloride, bicarbonate Intracellular: potassium, magnesium,

phosphate, protein

17

Osmotic Pressure

Osmotic pressure is the hydrostatic pressure that must be applied to the solution of greater concentration to prevent water movement across a semi-permeable membrane separating two aqueous solutions of unequal concentration

Osmotic pressure is dependent on the number of osmotically active molecules in solution

18

Osmotic Pressure 1 Osmole (Osm)

= 1 gram-molecular weight (1 M) of a nondissociating compound and consists of 6.023 x 1023 molecules

Osmolarity (mOsm / L) = the number of osmoles of solute per liter of solution (solvent

plus solute)

Osmolality (mOsm / kg H2O) = the number of osmoles of solute per kilogram of solvent (water)

Osmotic pressure = osmolality x 19.3 (mmHg)


10 mEq/l 142 mEq/l

Sodium balance

20

Plasma Osmolality

[Gluc] [BUN]Sosm (mOsm/kg H2O) = (2 x [Na+]) + + 18 2.8

[Na+] in mEq/lGlucose in mg/dlBUN = blood urea nitrogen in mg/dl

Serum osmolality < 260 mOsm/kg H2OSerum osmolality > 325 mOsm/kg H2O

Neurologic abnormalities•Confusion•Obtundation•Abnormal muscular activity•Seizures

Extracellular osmolality = 290 ± 10 mOsm/kg H2O


Sodium balance

Oncotic pressure Membrane permeability

Hydrostatic pressureLymphatic drainage

ProteIns

23

Starling’s Equation

Q = kA [ ( Pc - Pi ) + ( i - c ) ] (mEq / L)

Q = fluid filtrationk = capillary filtration coefficientA = area of the capillary membranePc = capillary hydrostatic pressurePi = interstitial hydrostatic pressure = reflection coefficient for albumini = interstitial colloid osmotic pressurec = capillary colloid osmotic pressure

Osmolality (mOsm/kg)

Plasma ISF

[Na+] (non-protein) 281.4 281.1

Protein 1.2 0.2

Total 282.6 281.3

Plasma ISF

[Na+] (non-protein) 5431.0 5425.2

Protein 23.2 3.9

Total 5454.2 5429.1

25.1 mmHg

Osmotic pressure (mmHg)

Capillary

Arterial Venous

Interstitium

Lymphatic drainage

Pc = 40 mmHg

Pc = 10 mmHg

c = 23 mmHg

Pi = 2 mmHgi = 4 mmHg

Filtration Absorption

c = 18 mmHg

27

Control of Body Fluid Compartments

Atrial natriuretic peptide Vasopressine Renin, angiotensin Parathyroid hormone Calcitonin Prostaglandins Dopaminergic receptors -adrenergic receptors Thirst mechanism Intrinsic renal properties

28

Volume and Electrolyte Status

Abnormalities of Volume Concentration Composition

Basis for assessment Medical history Physical examination Laboratory data

29

Volume changes (1)

Volume deficit Insufficient intake External losses Distributional volume deficit

Volume excess

30

Distributional Volume Deficit

Transfer of isotonic solution from a functional compartment to a nonfunctional space

Equivalent to ECF volume loss Isotonic Both ISF and PV contribute Same systemic manifestations as ECF loss

Surgical trauma, muscle injury, burns, peritonitis, ascites

Extracellular Fluid Deficit: Clinical Findings (1)

Decrease in body weight

(%)

Clinical signs

Mild 3 - 5 Dry mucous membranes, oliguria

Moderate

6 - 10 Orthostatic hypotension,

tachycardia, anorexia, apathy, poor skin

turgor

Extracellular Fluid Deficit: Clinical Findings (2)

Decrease in body weight

(%)

Clinical

signs

Severe 11 - 15 Supine hypotension, stupor, sunken eyes,

cool and dry skin, mild hypothermia

Catastrophic

> 20 Coma, anuria, significant in core

temp., dicrotic pulse, pulsus paradoxus,

circulatory collapse

33

Volume changes (2)

Volume deficit Volume excess

Iatrogenic Medical condition

Cardiac, hepatic or renal dysfunction Mobilization of third space losses

34

Concentration Changes

Loss of extracellular water

Increased serum [Na+]

Increased serum osmolality

Redistribution of water

Changes in osmolality and solute concentrations in other fluid compartments

Disorders of water balance

35

Changes in Composition

Changes in acid-base balance Changes in electrolytes

Sodium Calcium Magnesium Potassium

Changes in plasma proteins

36

Tonicity

Relative osmolality of solutions Isotonic

Osmotic pressure = osmotic pressure of body fluids Hypertonic

Osmotic pressure > osmotic pressure of body fluids intracellular volume depletion

HypotonicOsmotic pressure < osmotic pressure of body fluids cellular swelling

Extracellular Intracellular

Osm. Volume Osm. Volume

Water

Hypertonic salt solution

Isotonic salt solution

Loss of sodium chloride

Sugar(g/l)

Electrolytes Na K Ca Cl

(mEq/l)

Other anions(mEq/l)

Osmol(mOsm/l)

D5W 50 252

D5W + 40 mEq/l KCl

50 40 333

D10W 100 505

LR 130 4 3 109 28 273

D5W - LR 50 130 4 3 109 28 525

0.45% NaCl 77 77 154

0.9% NaCl 154 154 308

Albumin 5% 154 154 310

0

50

100

150

200

250

D5WLactatedRinger’s

Albumin5 %

Volume (ml)

Prough, Anesthesiology Clinics of North America (1996)

Administration of 250 ml of fluid

ICV

ISV

PV

Prough, Anesthesiology Clinics of North America (1996)

Administration of 250 ml of fluid

Volume (ml)

ICV

ISV

PV

-750

-500

-250

0

250

500

750

1000

D5W LR Alb 5% Alb 25%

41

Intraoperative Fluid Management

Volume, composition and concentration of intravenously administered fluids should beadjusted to maintain baseline function of

vital organ systems

42

Intraoperative Fluid Management

Basal fluid requirements Correction of preoperative fluid deficits

Fasting Disease-related fluid losses

Intraoperative fluid losses Blood loss Redistribution: ”Third space fluid loss” Other fluid losses

43

Basal Fluid and Electrolyte Losses (1)

Constant loss of water and electrolytes Skin

Insensible losses (evaporation) Perspiration

Lungs Insensible losses

Kidneys Gastrointestinal tract

Water (ml) Electrolytes

Skin Insensible 400

Perspiration 100 Na+

Lungs Insensible 400

Kidney Urine 1 500 K+

Gastro-intestinal

Feces 100 Na+, K+

Total 2 500

70 kg adult / 24 h

Basal water losses parallel energy expenditures Maintenance fluids (hospitalized pts): 100 ml/100 kcal/d

From Holliday MA and Segar WE, Pediatrics (1957)

1000

1500

17001900

2100 2300

2500

Computed need for average hospital patients

46

Decreased Metabolic Rate

Starvation Hypothyroidism Addison’s disease Obesity associated with hypothalamic or

pituitary dysfunction General anesthesia Extremes of age

47

Increased Metabolic Rate Skeletal muscle activity Ingestion of nutrients Caffeine, nicotine Fever, sepsis Elevated ambient temperature Diabetes insipidus Leukemia Polycythemia Dyspnea associated with cardiac, pulmonary,

renal disease

Normal activity and temperature

Normal activity, high temperature

Urine 1400 1200

Sweat 100 1400

Feces 100 100

Insensible loss 700 600

Total 2300 3300

Daily loss of water (mL)

From Rhoades and Tanner, Medical Physiology, Little, Brown & Co., Boston (1995)

49


Volume Basal water losses parallel energy

expenditures 4-2-1 RuleWeight

(kg)Volume required

0-10 4 ml/kg/h

11-20 40 ml/h + 2 ml/kg/h above 10 kg

> 20 60 ml/h + 1 ml/kg/h above 20 kg

Weight (kg) Volume 70 kg

0 – 10 4 ml/kg/h 40

11 - 20 2 ml/kg/h 20

> 20 1 ml/kg/h 50

Total 110 ml/h

“4-2-1” rule

51


Electrolytes Sodium: 1 – 2 mEq/kg/d Potassium: 1 – 1.5 mEq/kg/d Calcium: 1 – 1.5 mEq/kg/d

52

Intraoperative Fluid Administration

Maintenance fluids Correction of fluid deficit Replacement of intraoperative fluid losses

53

Intraoperative Maintenance Fluids (1)

Volume “4-2-1” rule Possibly increased intraoperatively

Fever Sweating Denuded skin Exposed peritoneal or pleural surfaces Non-humidified gasses, at high flow rates

54


Composition Water

D5W Electrolytes

Not for minor surgery in healthy patients Potassium

Bowel preparation

55


Glucose Indicated in type I diabetes mellitus

2-3 g/kg/d Indicated if risk of hypoglycemia

Total parenteral nutrition Insulinoma Prolonged (> 24 h) fasting Starvation

Avoid if risk of cerebral ischemia Hyperglycemia-induced cerebral acidosis

56

Correction of Preoperative Fluid Deficit

Preoperative fasting fluid deficit Basal maint. fluids/h x npo period (h)

1st hour: 50 % of deficit 2nd hour: 25 % of deficit 3rd hour: 25 % of deficit

Additional fluid deficits Disease-related fluid losses

External Internal

Elhakim et al., Acta Anaesth Scand (1998), 42

Time

VAS for nausea

(mm)

1 h 2 h 4 h 6 h 24 h48 h72 h0

5

10

15

20

25

30

Crystalloid

No crystalloid

**

*

**

* P>0.05

Elhakim et al., Acta Anaesth Scand (1998), 42* P>0.05

Vomiting (n)

Crystalloid No crystalloid

Day unit (6 h) 2 3

6 h – 3 d 0 8

0 - 2 h 2 2

2 - 4 h 0 1

4 - 6 h 0 0

6 - 24 h 0 8

24 - 48 h 0 3

48 - 72 h 0 1

*

59

External Fluid Losses

Gastrointestinal tract Vomiting, diarrhea, ostomy output,

overzealous bowel preparation Hidden: bowel obstruction, ileus Volume, concentration and composition

disturbances External blood loss

Gastrointestinal bleeding Traumatic injuries

Volume and composition of gastrointestinal fluids

From Miller, Anesthesia, 5th ed.

24 h vol. (mL)

Na+ (mEq/L)

K+ (mEq/L)

Cl- (mEq/L)

HCO3-

(mEq/L)

Saliva 500-2000 2-10 20-30 8-18 30

Stomach 1000-2000 60-100 10-20 100-130 0

Pancreas 300-800 135-145 5-10 70-90 95-120

Bile 300-600 135-145 5-10 90-130 30-40

Jejunum 2000-4000 120-140 5-10 90-140 30-40

Ileum 1000-2000 80-150 2-8 45-140 30

Colon - 60 30 40 -

61

Internal Fluid Losses (1)

Sequestered ECF pool Cavitary fluid losses

Pathologic transudate of plasma (pleural, ascitic, pericardial)

Anatomical compartment Develop slowly compensation

Third space fluid losses Extracellular tissue fluid Non-anatomical compartment Develop quickly considerable impact on ECF

Internal blood loss

62

Internal Fluid Losses (2)

Sequestered ECF pool Cavitary fluid losses Third space fluid losses Internal blood loss

Retroperitoneal hematoma Aorta aneurysm Leaking vascular anastomosis Pelvic or femoral fracture Splenic rupture Liver trauma

63

Correction of Preoperative Disease-related Fluid Losses (1)

Assessment of ECF volume deficit 1 % in body weight 10 ml/kg fluid

e.g. moderate fluid loss: 8% of body weight 70 kg 8 x 10 x 70 = 5 600 ml

Isotonic fluid: water + salt Normal saline (NaCl 0.9%) Balanced salt solution

e.g. lactated Ringer’s

64

Correction of Preoperative Disease-related Fluid Losses (2)

Ideally: preoperative correction < 20 % of blood volume

Replace over 15 min Redistribution to ISF: 40-60 % within 15-30 min 75 %

within 60 min Large deficit and surgery not urgent

Replace 25-50 % over 1 h Remainder over several hours

Correction of electrolyte abnormalities

65

Replacement of Intraoperative Fluid Losses (1)

Blood loss Redistribution and subsequent loss of

extracellular and intracellular fluid Replacement with crystalloids

Volume blood:crystalloid ratio 3:1 to 5:1 (even 7:1)

Composition NaCl 0.9 % Balanced electrolyte solution

Colloids Blood products

Third space losses

Cervera et al., Am J Surg (1975), 129

67

Replacement of Intraoperative Fluid Losses(2)

Redistribution: “Third space fluid loss” Sequestered extracellular fluid Volume related to surgical trauma

Minor: 2 - 4 ml/kg/h Intermediate: 4 - 8 ml/kg/h Major: 8 - 15 ml/kg/h

Replacement fluid NaCl 0.9 % Balanced electrolyte solution

Continues 24 – 48 h Mobilization 1 – 3 days postoperatively

Roberts et al., Ann Surg (1985), 202

Lactated Ringer’s D5W

Fluid (ml) 1660 ± 96 530 ± 92

Duration (min) 253 ±50 187 ± 113

ECV preop (l) 12.5 ± 2.3 12.5 ± 2.4

ECV postop (l) 12.3 ± 7.0 10.6 ± 1.9

* P<0.05 between groups** P<0.05 vs preop

**

*

69

Postoperative Fluid Losses

Basal fluid losses Internal fluid losses

Third space loss Blood loss Accumulation of fluid within body cavities

External fluid losses Blood loss Enhanced insensible loss Transcellular fluid loss

70

Postoperative Fluid Therapy

Basal fluid loss + increased insensible loss Hypotonic maintenance fluids Until adequate oral intake

All other postoperative fluid losses Balanced salt solution + electrolytes

Postoperative day 1- 3: mobilization of third space fluid losses

71

Intraoperative Fluid Therapy: Lack of Good Target Points (1)

Cardiovascular parameters ECG Blood pressure Central venous pressure Pulmonary artery catheter Transesophageal echocardiography

Perfusion directed therapy Fluid overload

72


Cardiovascular parameters Perfusion directed therapy

Global Lactate

Regional: Gastrointestinal Gastrointestinal Pco2 tonometry

Organ specific Kidney: urine output

Fluid overload

73


Fluid overload Intraoperative absorption of irrigating fluids

during endoscopic surgery Transurethral resection of the prostate Hysteroscopic surgery Absorption can be accurately monitored

74

Fatal Postoperative Pulmonary Edema: Pathogenesis and Literature Review(Arieff: Chest 1999, 115: 1371-1377)

Fatal postoperative pulmonary edema 13 patients (incidence of 0.02 %)

10 generally healthy 3 serious associated medical conditions Age 38 ± 21 y

Within 3 postoperative days Range: 3 to 66 h, mean ± SD: 27 ± 20 h

No predictive variables No predictive warning signs

Cardiorespiratory arrest first clinical sign in 8 pts Fluid overload as single cause

Mean net fluid retention of 7.0 ± 4.5 l first 27 h postop (24 % increase of total body water)

75

Hyperchloremic Metabolic Acidosis

“Dilutional acidosis” Metabolic acidosis resulting from rapid

administration of fluids that contain near-physiologic concentrations of sodium accompanied by anions (usually chloride) other than bicarbonate or bicarbonate precursors, such as lactate. (D.S. Prough, Anesthesiology 2000)

Dose-dependent

76

Rapid Saline Infusion Produces Hyperchloremic Acidosis in Patients Undergoing Gynecological Surgery.(Scheingraber et al.: Anesthesiology 1999, 90)

Saline(n = 12)

Lact. Ringer’s (n = 12)

Time of infusion (min) 135 ± 23 138 ± 20

Volume after 120 min (ml/kg)

71 ± 14 67 ± 18

Estimated blood loss (ml) 962 ± 332 704 ± 447

Urine output (ml) 717 ± 459 1 075 ± 799

Scheingraber et al., Anesthesiology 90 (1999)

Saline Lactated Ringer ’s

0 min 120 min 0 min 120 min

Bicarbonate

(mM)23.5 ± 2.2 18.4 ± 2.0 23.3 ± 2.0 23.0 ± 1.1

Anion gap (mM)

16.2 ± 1.2 11.8 ± 1.4 15.8 ± 1.4 12.5 ± 1.8

Chloride (mM)

104 115 104 106


Lactated Ringer’sNormal saline

7.50

7.45

7.40

7.35

7.30

7.25

7.200 30 60 90 120 min 0 30 60 90 120 min

0 30 60 90 120 min0 30 60 90 120 min

50

46

42

38

34

30

26

4

0

-4

-8

-12

3.0

2.5

2.0

1.5

1.0

0.5

0.0

mm

Hg

mm

ol/

l

mm

ol/

lpH Carbon dioxide

Base excess Lactate

# # #

### #*

#*

#* #*

*

*

** *

** *

* P<0.05 intragroup# P<0.05 intergroup


Lactated Ringer’sNormal saline

Sodium Chloride

Calculated SID Prot-

0 30 60 90 120 min 0 30 60 90 120 min

0 30 60 90 120 min0 30 60 90 120 min

148

144

140

136

120

115

110

105

100

17.5

15

12.5

10

7.5

45

40

35

30

25

mm

ol/

l

mm

ol/

l

mm

ol/

l

mm

ol/

l

#*#* #*

#*#*

#*#*

#*

#*#*

**

**

***

*

**

*

***

*

**

**

**

* P<0.05 intragroup# P<0.05 intergroup

Replacing 1 Liter of Blood Loss with Crystalloid (3:1)

Crystalloid Excess chloride load(mmol)

3 l of NaCl 0.9 % 165

3 l of lactated Ringer’s 27

81

Hyperchloremic Metabolic Acidosis: Therapy

Switch to balanced electrolyte solution Lactated Ringer’s Plasmalyte

Hyperventilation pH > 7.2 and preferably > 7.3

Furosemide (Fresh frozen plasma)

Transfusion criteria

82

Plasma Volume Expansion (PVE): Static Concept

Plasma volumePVE = Volume infused x

Distribution vol.

Distribution volume:D5W = total body waterLactated Ringer’s = extracellular vol.NaCl 0.9% = extracellular vol.

One-compartment Volume of Fluid Space Model

Ki V V

Kb Kr(V - V)

V

V = expandable space of volume

V = target volume

Ki = constant fluid infusion rate

Kb = basal rate of fluid elimination (perspiration, basal diuresis)

Controlled rate of fluid elimination proportional by a constant Kr to the relative deviation of v from V

Svensén et al., Anesthesiology (1997), 87

Two-compartment Volume of Fluid Space Model

The net rate of fluid exchange between the 2 compartments is proportional to the difference in relative deviations from the target volumes by a constant Kt

Ki V1V1

Kb Kr(V1 - V1)

V1

Kt

V2 V2

Secondary fluid space

Svensén et al., Anesthesiology (1997), 87

85

Plasma Volume Expansion (PVE): Kinetic Analysis

Bolus of fluid Peak effects Rates of clearance

Infusion of fluid necessary to maintain PVE at a certain level

Effects of anesthesia, surgery and trauma on fluid requirements

Usefull during severe pathophysiologic disturbances?

0 20 40 60 80 100 120Time (min)

0 20 40 60 80 100 120Time (min)

0.2

0.15

0.10

0.05

0

0.2

0.15

0.10

0.05

0

Pla

sm

a d

ilu

tion

, (v

– V

)/V Single bolus of Ringer’s

40 ml/min for 40 min

Bolus + continuous infusion of Ringer’s at 25 ml/min

Hahn and Svensen, Br J Anaesth (1997), 79

Hahn and Svensen, Br J Anaesth (1997), 79

88

Volume Kinetics of Ringer’s Solution during Induction of Spinal and General Anaesthesia. (Ewaldsson and Hahn: Br J Anaesth 2001, 87)

10 patients: 20 ml/kg of Ringer acetate over 60 min (0.33 ml/kg/min) Spinal anesthesia 20 min after start of infusion

5 patients: 350 ml of Ringer’s over 2 min immediately after spinal

followed by Ringer’s at 0.33 ml/kg/min Ephedrine 5-10 mg IV if SAP < 60 % of baseline Parameters

Blood pressure Blood hemoglobin concentration

Every 3 min during 60 min

Ewaldsson and Hahn, Br J Anaesth (2001), 87

Spinal anesthesia

Rapid infusion group

0.33 ml/kg/min during 60 min

0.33 ml/kg/min during 40 min350 ml over 2 min

Semipermeable membrane

Solvent

Osmosis

Solute

Solution

Osmoticpressure

3. Fluid Electrolyte in Anesthesia

Documents

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intraoperative

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