Anesthesiology - Fluid Management

Front 1

What is the ultimate consequence of indadequate fluid management?

Back 1

Hypovolemic shock

Front 2

Which three factors must peri-operative fluid management take into account?

Back 2

1) Pre-operative fluid deficit

2) Normal fluid maintenance

3) Intra-operative losses

Front 3

Why do most patients going for an operation have a pre-operative fluid deficit?

Back 3

They've been NPO

Front 4

How are maintenance fluid requirements calculated?

Back 4

4:2:1 rule

First ten kilos: 4 mL/kg/hr

Second ten kilos: 2 mL/kg/hr

Every kilo after that: 1mL/kg/hr

Front 5

How do you calculate the patient's pre-operative fluid deficit?

Back 5

Normal maintenance requirements (4:2:1 rule) x number of hours NPO

Other factors may come into play, such as fluid loss through vomiting, NG tube losses, diarrhea, and sweating.

Front 6

If the patient has been febrile, what effect will that have on their maintenance fluid requirements?

Back 6

Increase maintenance requirements by 10% for every degree Celcius elevation in temperature.

Front 7

At what stage should the patient's pre-operative fluid deficit be replaced?

Back 7

As a rule, half of the deficit should be corrected prior to induction, and the remainder replaced intra-operatively.

However, if the pre-operative deficit is greater than 50% of estimated blood volume, then the surgery should be delayed, if possible, to allow for rehydration.

Front 8

Which two factors contribute to intra-operative fluid loss?

Back 8

1) Blood loss

2) Third spacing

Front 9

How do you estimate the amount of fluid lost intra-operatively to third spacing?

Back 9

It is estimated base on the nature of the surgery.

Minimal surgical trauma (orthopaedic surgery): 2-5cc/kg/hr

Moderate surgical trauma (bowel resection): 5-10 cc/kg/hr

Major surgical trauma (abdominal aortic aneurysm repair): 10-15cc/kg/hr

Front 10

Estimate the fluid loss due to third spacing in a surgery with minimal trauma (e.g. orthopaedic surgery).

Back 10

2-5mL/kg/hr

Front 11

Estimate the amount of fluid loss due to third spacing in a surgery with moderate surgical trauma (e.g. bowel resection).

Back 11

5-10 mL/kg/hr

Front 12

Estimate the amount of fluid loss due to third spacing in a surgery with major surgical trauma (e.g. abdominal aortic aneurysm repair)

Back 12

10-15 mL/kg/hr

Front 13

True or false?

Blood loss is usually overestimated.

Back 13

FALSE!

Blood loss is usually underestimated.

Front 14

How can intra-operative blood loss be estimated?

Back 14

1) Direct observation

2) Physiologic assessment

Front 15

Name three things can be visually inspected in order to estimate intra-operative blood loss?

Back 15

1) Suction
2) Sponges
3) "Loose" blood (blood on surgical field, drapes, floor)

Front 16

What is the best way to judge the adequacy of your fluid replacement for the patient?

Back 16

The patient's response to therapy

E.g. urine output greater than 1.0 cc/kg/hr

Other, less specific indicators of adequate tissue perfusion include hemodynamic stability, pH, and central venous pressure.

Front 17

What is central venous pressure?

Back 17

Pressure of blood in the thoracic vena cava, near the right atrium of the heart

Front 18

How is the severity of hemorrhagic shock classified?

Back 18

Four classes based on amount of blood loss.

Class 1: <15% blood loss
Class 2: 15-30% blood loss
Class 3: 30-40% blood loss
Class 4: >40% blood loss

The amount of blood loss can be estimated clinically the patient's status across six parameters: pulse rate, blood pressure, pulse pressure, respiratory rate, urine output, and mental status.

Front 19

A person with Class 1 hemorrhagic shock has lost what percentage of their blood?

Back 19

15% or less

Front 20

A person with Class 2 hemorrhagic shock has lost what percentage of their blood?

Back 20

15-30%

Front 21

A person with Class 3 hemorrhagic shock has lost what percentage of their blood?

Back 21

30-40%

Front 22

A person with Class 4 hemorrhagic shock has lost what percentage of their blood?

Back 22

>40%

Front 23

Which 6 clinical parameters are used to estimate a patient's percentage blood loss and classify the severity of their hemorrhagic shock?

Back 23

Vital signs:
1) Heart rate
2) Blood pressure
3) Pulse pressure
4) Respiratory rate

Ins/Outs
5) Urine output

Other
6) Mental status

Front 24

What are the two most reliable signs of early hypovolemia?

Back 24

Decreased urine output
Decreased pulse pressure

Front 25

What is pulse pressure?

Back 25

Difference between systolic and diastolic blood pressure

Front 26

What might a decrease in pulse pressure indicate?

Back 26

Indicates hypovolemia

Front 27

A person who has lost 15-30% of their blood has Class ___ hemorrhagic shock.

Back 27

Class 2

Front 28

A person who has lost 15% or less of their blood has Class ___ hemorrhagic shock.

Back 28

Class 1

Front 29

A person who has lost 30-40% of their blood has Class ___ hemorrhagic shock?

Back 29

Class 3

Front 30

A person who has lost 40% or greater of their blood has Class ___ hemorrhagic shock.

Back 30

Class 4

Front 31

Estimate the 70 kg patient's percent blood loss and classify the severity of their hemorrhagic shock:

Pulse rate: <100

Blood pressure: normal

Pulse pressure: normal

Respiratory rate: normal

Urine output: >30 cc/hr

Mental status: normal

Back 31

The patient is either not in hemorrhagic shock or has Class1 hemorrhagic shock with less than 15% blood loss.

Front 32

Estimate the 70 kg patient's percent blood loss and classify the severity of their hemorrhagic shock:

Pulse rate: 100-120

Blood pressure: orthostatic drop

Pulse pressure: decreased

Respiratory rate: 20-30

Urine output: 20-30 cc/hr

Mental status: anxious

Back 32

15-30% blood loss, Class 2 hemorrhagic shock

Front 33

Estimate the 70 kg patient's percent blood loss and classify the severity of their hemorrhagic shock:

Pulse rate: 120-140

Blood pressure: decreased

Pulse pressure: decreased

Respiratory rate: 30-40

Urine output: <20 cc/hr

Mental status: confused

Back 33

30-40% blood loss, Class 3 hemorrhagic shock

Front 34

Estimate the 70 kg patient's percent blood loss and classify the severity of their hemorrhagic shock:

Pulse rate: >140

Blood pressure: decreased

Pulse pressure: decreased

Respiratory rate: >40

Urine output: negligible

Mental status: lethargic

Back 34

>40% blood loss, Class 4 hemorrhagic shock

Front 35

What is the first change in mental status that would indicate volume depletion?

Back 35

Anxiety, then confusion, then lethargy

Front 36

At what percentage of blood loss does a patient start to become symptomatic?

Back 36

Around 15%

Front 37

Will a patient who has lost blood acutely show a low hemoglobin or hematocrit?

Back 37

No

Hemoglobin (as a concentration) and hematocrit (as a ratio) remain the same until intravascular volume has been restored with non-blood containing solutions.

Only after euvolemia has been restored is the hemoglobin level a useful guide for transfusion.

Front 38

Is lactic acidosis an early or late sign of impaired tissue perfusion?

Back 38

Late

Front 39

Which will allow for greater flow, a 14 gauge peripheral IV or a 14 gauge central line?

Why?

Back 39

The peripheral IV will allow for greater flow because the central line, by necessity, is longer.

Resistance is directly proportional to the length of tube that the fluid is flowing through.

Front 40

Name 10 potential complications of central venous cannulation.

Back 40

Arterial puncture, hemorrhage, pneumothorax, thoracic duct injury, neural injury, air embolism

Infection, thrombosis, hydrothorax, catheter misplacement, catheter/wire embolism.

Front 41

How do you estimate blood volume in the adult?

Back 41

60-70 mL/kg

Front 42

How do you calculate lowest allowable hemoglobin in a patient for a healthy patient?

Back 42

About half of a normal hemoglobin.

Front 43

What is transcellular fluid?

Back 43

Transcellular fluid is the fluid within the peritoneum and pleural spaces.

Front 44

How do you replace presumed third space losses during surgery?

Back 44

Minor trauma (ortho, soft tissue) - 4 mL/kg/hr

Moderate trauma (bowel, bladder resection) - 6 mL/kg/hr

Major trauma (abdominal aorta resection)
- 8 mL/kg/hr

Front 45

In the solution known as "two-thirds, one third," what comprises the two-thirds and what is the one-third?

Back 45

2/3 D5W and 1/3 NS

Front 46

Into which space/spaces do colloid solutions distribute?

Back 46

Colloid solutions remain within the intravascular space.

They also cause some interstitial fluid to enter the intravascular space.

Colloid solutions thus expand blood volume.