Intravascular_Fluid_Therapy_anesthesia__b7ca9904.ppt

Fluid Management
Jeffrey Groom, PhD, CRNA
Director and Clinical Associate Professor
Nurse Anesthetist Program
Florida International University

Goal of perioperative fluid management
The goal of perioperative fluid management is to
provide the appropriate amount of parenteral
fluid to maintain adequate:
– intravascular fluid volume,
– left ventricular filling pressure,
– cardiac output,
– systemic blood pressure,
– and ultimately, oxygen delivery to tissues.

Rational approach to fluid management
In addition to surgical considerations
(blood loss, evaporative loss, third spacing),
certain conditions and changes that occur during
the perioperative period can make the
management of fluid balance a challenge,
including preoperative:
• fluid volume status,
• preexisting disease states,
• and the effect of anesthetic drugs on normal
physiology

Management of fluid therapy
• Management of fluid therapy may influence
intraoperative and postoperative morbidity and
mortality.
• Providing sufficient intravascular fluid volume is
essential for adequate perfusion of vital organs.
• Although quantitative considerations are of primary
concern, oxygen carrying capacity, coagulation,
and electrolyte and acid-base balance are also of
critical importance.

Preoperative assessment of
intravascular fluid volume
Preoperative assessment of intravascular fluid volume is
important before induction of anesthesia.
• Common causes of preoperative hypovolemia:
– Bowel preparations, vomiting, diarrhea, diaphoresis,
hemorrhage, burns, and inadequate intake
• Redistribution of intravascular fluid volume without evidence of
external loss is another important cause of preoperative
volume depletion.
– Examples: patients with sepsis, adult respiratory distress
syndrome, ascites, pleural effusions, and bowel
abnormalities.
• Often, these processes are accompanied by increased
capillary permeability resulting in loss of intravascular fluid
volume to interstitial and other fluid compartments.

Evaluation of intravascular fluid volume
• Evaluation of intravascular fluid volume relies on
indirect measurements such as systemic blood
pressure, heart rate, and urine output because
measurements of fluid compartments are not readily
available.
• Even with sophisticated monitoring techniques
(pulmonary artery catheters, arterial oxygen
saturation), the adequacy of intravascular fluid volume
replacement and tissue oxygen delivery to individual
vital organs cannot be precisely determined.
• For these reasons, clinical evaluation of intravascular
fluid volume is necessary.

Clinical Estimation of
Intravascular Fluid Volume

INTRAVASCULAR FLUID VOLUME STATUS
AND ANESTHETIC TECHNIQUE
• Induction of anesthesia with thiopental leads to a
decrease in venous return.
• Induction of anesthesia with propofol produces a
decrease in systemic vascular resistance, cardiac
contractility, and preload.
• Ketamine produces increases in systemic blood
pressure, heart rate, and cardiac output through
stimulation of the sympathetic nervous system and
inhibition of norepinephrine reuptake.
– Direct myocardial depressant effects of ketamine may be
unmasked by exhaustion of catecholamine stores
(congestive heart failure, end-stage shock) and result in
paradoxical decreases in blood pressure when ketamine is
administered

• Neuromuscular blocking drugs, though generally
devoid of direct cardiovascular effects, can lead to
histamine release (Sux, Atracurium) and decreased
systemic vascular resistance or produce venous
pooling because of loss of muscle tone.
• Isoflurane, desflurane, and sevoflurane all decrease
systemic vascular resistance and mildly depress
myocardial contractility. In addition, institution of
positive-pressure ventilation of the patient’s lungs
reduces preload and is particularly likely to decrease
systemic blood pressure in hypovolemic patients.

• Regional Anesthesia (Spinal & Epidural)
AKA Neuraxial blockade - block sympathetic
nervous system fibers innervating arterial and
venous vascular smooth muscle, causes
vasodilatation, pooling of blood, and decreased
venous return to the heart.
• May cause significant changes in systemic blood
pressure, especially in intravascularly depleted
patients.
• These effects are often mitigated by fluid
administration before the institution of regional
anesthesia.

PERIOPERATIVE FLUID THERAPY:
QUANTITATIVE CONSIDERATIONS
Perioperative fluid therapy includes:
1. Replacement of preexisting fluid deficits,
2. Replacement of normal losses
(maintenance requirements)
3. Replacement of surgical wound (“third-
space”) losses
4. Replacement of surgical wound
(bleeding) losses

QUALITATIVE CONSIDERATIONS
Crystalloid solutions – NS, LR, Plasma-lyte, Dextrose solutions
• NS - large volumes can lead to a hyperchloremic-induced non-gap
metabolic acidosis
• LR - large volumes can lead to an increased bicarbonate production
from the metabolism of lactate and induce metabolic alkalosis
• LR and Plasma-Lyte contain potassium and should be used with
caution in hyperkalemic patients.
• Calcium in LR prohibits its use in the presence of citrated blood
products.
• Dextrose-containing solutions should be avoided because
hyperglycemic-induced hyperosmolality, osmotic diuresis, and
cerebral acidosis are known complications.
• Infusions of total parenteral nutrition solutions should be continued
during anesthesia and surgery to prevent hypoglycemia; or
alternatively administer dextrose-containing infusion. In either case,
monitor intra op blood glucose.

• Colloid solutions – albumin, hydroxyethyl starch, and dextran
• Albumin (5% or 25%) is purified from human plasma
– there is no known risk of transmission of hepatitis B or C or HIV.
– However, because albumin is a blood product, Jehovah’s Witness patients
may object to its use for religious reasons.
– The half-life of albumin in plasma is approximately 16 hours, with about 90%
of the dose remaining in the intravascular space 2 hours.
• Hydroxyethyl starch (hetastarch) is a semisynthetic colloid synthesized from
amylopectin
– 6% high-molecular-weight hetastarch in saline (Hespan)
– 6% high-molecular-weight hetastarch in balanced electrolytes (Hextend)
– The half-life for 90% of hydroxyethyl starch particles is 17 days.
• Dextran is a semisynthetic colloid biosynthesized from sucrose
– Based on differing molecular weights, dextran 70 is generally preferred for
volume expansion, whereas dextran 40 is thought to improve blood flow in
the microcirculation, presumably by decreasing blood viscosity.
• Hypersensitivity reactions, including anaphylaxis, have been reported with
albumin, hydroxyethyl starch, and dextran.
• Considerably more expensive than crystalloids.

COAGULATION ABNORMALITIES
• Bleeding associated with the use of the synthetic colloids has been widely
reported.
• Dextran 70 and, to a lesser extent, dextran 40 produce a dose-related
reduction in platelet aggregation and adhesiveness.
• Hydroxyethyl starch can lead to a reduction in factor VIII and von Willebrand
factor, impairment of platelet function, and prolongation of the partial
thromboplastin time.
• Coagulation studies and bleeding times are not generally significantly
affected after infusions of up to 1 L.
• However, these colloids are best avoided in patients with a known
coagulopathy.
Colloid versus Crystalloid Solutions
• Numerous comparison studies with NO distinct advantages
• Because colloids are more expensive and do not have the same safety
profile as crystalloids, it is hard to justify their use outside situations in which
rapid intravascular fluid volume expansion is needed.

1. Replacement of preexisting fluid deficits
Examples: _____ ml/hr minimum maintenance req
60 kg = ______ 100 kg = _____ 200 kg = _____
Sometimes called
the “4-2-1 Rule”

Sometimes called
the “4-2-1 Rule”
Quick Version for patients over 20kg is to take weight (kg) plus 40 (ml/hr)
Hourly Maintenance Fluid Rate ___kg + 40ml = ____ ml/hr
Ex 120 kg pt 120kg + 40 = 160 ml/hr

Perioperative fluid therapy based on:
• The predicted daily maintenance fluid
requirements for healthy adults may exceed
2500ml/day including 20 mEq/L Sodium and
15-20mEq/L Potassium
• Insensible loss (diaphoresis, respiration, etc.)
may exceed 1000ml/day
• Urinary losses to maintain renal function average
1000ml/day, GI losses 200ml/day

Hourly Maintenance Fluid Requirement
X Hours NPO
Fluid Deficit
Examples: _____ ml Estimated Fluid Deficit
60kg/8hr = ___ 100kg/10hr = ___ 200kg/12hr= ___

usually over 3 hours
1stHR ½ 2nd HR ¼ 3rd HR ¼
Examples: _____ ml Estimated Fluid Deficit
1000 ml deficit = ___ ml 1st HR
___ ml 2nd HR
___ ml 3rd HR

Abnormal fluid losses (vomiting, diarrhea, preoperative
bleeding), occult losses (ascites, infected tissues), and
insensible losses (fever, sweating, hyperventilation) must
not be overlooked in the preoperative correction of fluid
deficits so that the hypotension and hypoperfusion that
can occur during induction of anesthesia can be minimized.
(Clinical estimation - No formula for replacement amount)
The fluid used for replacement should be similar in
composition to the fluid lost (Crystalloids).

2. Replacement of normal losses
(maintenance requirements)
_____ ml/hr minimum maintenance requirements
(Administered With or Without Surgery Losses)

(“third-space”) losses

(bleeding) losses
Replace 1 mL of blood loss with 3 mL crystalloid solution
Examples:
100ml blood = ___ml cryst
500ml blood = ___ml cryst

(bleeding) losses
Replace 1 mL of blood loss with 3 mL crystalloid solution
4x4 = 10 ml blood
Lap = 100-150 ml

• Continually record ongoing estimates of surgical blood loss.
• Include: Measurement of blood in the surgical suction container;
• Estimate: occult bleeding into the wound or under surgical drapes
• Estimate: blood on surgical sponges and laparotomy pads (“laps”)
• Use of irrigating solutions may also complicate the estimates.
• Serial hematocrit values reflect the ratio of blood cells to plasma, not
blood loss.
• Typically, surgeons and anesthesia providers underestimate actual
blood loss.
• Clinical signs such as tachycardia are insensitive and nonspecific.
• Decreasing urine output, decline in arterial pH, and a rising base deficit
may be manifested only when tissue hypoperfusion has become
moderate to severe.
• Therefore, visual estimation of continual blood loss is mandatory to guide
fluid therapy and transfusion.
Replace blood loss with isotonic crystalloid solution at 3ml : 1ml blood loss ratio,
-OR-
milliliter-per-milliliter replacement with colloid or blood

*
*
Hourly Maintenance Fluid Rate (4-2-1 Rule ml/hr)

60 kg man with 10 hour NPO
having Hemicolectomy 1st Hr 2nd Hr 3rd Hr 4th Hr
Insensible loss 120ml 120ml 120ml 120ml
Deficit 500ml 250ml 250ml -------
Replacement 6ml/kg/hr
When surg starts
360ml 360ml 360ml
Total Hour 620ml 730ml 730ml 480ml
Running Total 620ml 1350ml 2080ml 2560ml
EXAMPLE 1 (insensible Loss Rate)

Maintenance 100ml 100ml 100ml 100ml
Deficit 500ml 250ml 250ml -------
Replacement 8ml/kg/hr
When surg starts
480ml 480ml 480ml
EXAMPLE 2 (Maintenance Rate)

Insensible loss 120ml 120ml 120ml 120ml
Deficit 500ml 250ml 250ml -------
Replacement
Blood loss
6ml/kg/hr 360ml +
300ml
360ml 360ml
EXAMPLE 1 (insensible Loss Rate)

__ kg man with __ hour NPO
having _____-ectomy 1st Hr 2nd Hr 3rd Hr 4th Hr
Insensible loss
(2ml/kg/hr)
Deficit
(adjust prn)
Replacement
(use lower end)
Bleeding
(3:1 Cryst:blood)
Total Hour
Running Total
EXAM (insensible Loss Rate)

Transfusion Considerations
• Considered on a case by case basis
• Blood loss should be replaced with crystalloid or colloid solutions to
maintain intravascular fluid volume until the danger of anemia or
depletion of coagulation factors necessitates the administration of
blood products.
• Below a hemoglobin level of 7 g/dL, resting cardiac output has to
increase greatly to maintain normal oxygen delivery to tissues.
Therefore, blood loss should be replaced with transfusion of
erythrocytes to maintain a hemoglobin concentration between 7 and
8 g/dL. A level of 10 g/dL is generally desired for patients with
significant cardiac or pulmonary disease.
• The most common intraoperative coagulopathy is dilutional
thrombocytopenia, which occurs with either large-volume blood
product transfusion or crystalloid/ colloid administration.
• Factor deficiency is less common in the absence of hepatic
dysfunction because stored blood retains 20% to 30% activity of
factors VII and VIII, which is sufficient for coagulation.

Calculating Allowable Blood Loss
–Estimated Blood Volume (EBV) and ABL
• Blood Volume as a function of total body water
• Composition decreases with age
– Premature 100-120cc/kg
– Newborn 80-90cc/kg
– Infant (age 3-12 months) 75-80cc/kg
– Adult male 70cc/kg
– Adult female 65cc/kg

Hematocrit (70kg male initial crit 45% target 30%)
• If you know what the preoperative HCT is,
• Calculate MABL to a minimum target HCT:
MABL = (EBV) x (Starting HCT – Target HCT)
Starting HCT
MABL = (70cc/kg x 70kg) x (45%-30%)
45%
MABL = (4900) x (15)/45 = 1633ml
Estimate that PT will be at approximate Hct of 30% at a blood loss of 1633 ml

Hematocrit (100kg male initial crit 35% target 25%)
MABL = (EBV) x (Starting HCT – Target HCT)
Starting HCT
MABL = (70cc/kg x 100kg) x (35%-25%)
35%
MABL = (7000) x 10)/35 = 2000ml
Estimate that PT will be at approximate Hct of 25% at a blood loss of 2000 ml

Basics of Anesthesia
Blood Therapy Chapter 24
• Emergency Transfusion – Order of preference
• Type and Screen vs Type and Cross
• Decision to transfuse
• Blood components – PRBCs, Acute Loss,
Complications, FFP
• Transfusion reactions
• Autologous Blood – PreDeposit, Salvage,
Dilution
• Basic nursing procedures to administer blood
products – Safety checks, IV Setup,
Administration, Documentation

CASE - 40 yo 220lb hernia 10hr npo
• Convert pounds to kilograms
• Calculate maintenance
• Calculate deficit
• Calculate 3rd Space replacement
requirement
• Include possible need to replace
blood loss

100 kg man with 10 hour
NPO having herniorrhaphy 1st Hr 2nd Hr 3rd Hr 4th Hr
Insensible loss
Deficit
Replacement
Total Hour
Running Total

100 kg man with 10 hour
NPO having herniorrhaphy 1st Hr 2nd Hr 3rd Hr 4th Hr
Insensible loss
Deficit
Replacement
Blood loss (200cc)
Blood loss replacement with
IV Crystalloids
100 loss 100 loss
Total Hour
Running
Urine Output

Calculating allowable blood loss
Hematocrit (70kg female initial crit 45% target 30%)

Exam I
• Surgical Services (5% slides/Stoelting Ch3)
• Preanesthesia Assessment (30% slides/text)
• Surgical Patient Positioning (30% slides/text)
• Fluid Management (35% slides/text)

Intravascular_Fluid_Therapy_anesthesia__b7ca9904.ppt

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