Dịch truyền tĩnh mạch – Sẽ đi đâu sau truyền 1h - Professor Brendan Smith

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<b>IV Fluid –</b>

<b>Where Will It Be One Hour From Now?</b>

<b>Professor Brendan Smith .</b>

School of Biomedical Science, Charles Sturt University,
Medical School, University of Notre Dame, Australia,

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Choose a number between 1 and 36.

Remember your number…

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iv fluid is used in every hospital on earth every day!

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But does it have to be intravenous

fluid?

What about

<b>oral</b>

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Dr Thomas Latta

– Scotland – 1832

(Cholera epidemic)

1 ounce = 30ml

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Dr Thomas Latta

– Scotland – 1832

(Cholera epidemic)

1 ounce = 30ml

Six pints = 3.4 litres

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How did we get from small volumes of

fluid to 8, 10, 15+ litres?

The average volume of blood in an adult

<b>= 5 litres</b>

The average plasma volume

<b>= 3 Litres</b>

Even if there was no plasma left, why

would we ever need more than

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“Despite overwhelming data demonstrating the deleterious effects
of aggressive crystalloid-based resuscitation strategies,

large-volume resuscitations continue to be the standard of care”

<b>Bryan Cotton, Shock 2006; 26 (2): 115 - 121</b>

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<i>“If giving </i>

<i>1</i>

<i>or </i>

<i>2</i>

<i>(or </i>

<i>3</i>

<i>or </i>

<i>4</i>

<i>) litres of </i>

<i>normal saline doesn’t result in a </i>

<i>sustained increase in BP or oxygen </i>

<i>delivery, why would the </i>

<i>5</i>

<i>th</i>

<i>or </i>

<i>6</i>

<i>th</i>

<i>litre give you a different result?”</i>

<b>The “Fluid</b>

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<b>The curse of “fluid responsiveness”</b>

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<b>The curse of “fluid responsiveness”</b>

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Insert Vietnamese translation here.

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Insert Vietnamese translation here.

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Insert Vienamese translation here

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<b>The curse of “fluid responsiveness”</b>

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<b>The curse of “fluid responsiveness”</b>

Are you going to give

500ml

of crystalloid in 10 minutes

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Are clinical signs reliable indicators

of response to fluid?

It depends on their

sensitivity to change

,

and

on the

measurement error

of the method …

If the measurement error is large, e.g.

30%

then the change has to exceed

<b>at least 30%</b>

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Can you measure a hair

accurately using a ruler?

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<b>Sensitivity to Change</b>

Would you dose medication

using these scales?

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<b>Sensitivity to Change after Fluid Bolus</b>

<b>BP</b>

<b>Pulse Pressure </b>

(BPsystolic – BPdiastolic)

<b>Heart Rate</b>

What about <b>Cardiac Output </b>and <b>Stroke Volume?</b>

<b>Measurement Error of Methods</b>

Swan-Ganz <b>20 - 30%</b>

PiCCO <b>20 - 40%</b>

NiCOM (Cheetah) <b>25 - 45%</b>

ICG <b>30 - 70%</b>

15%

minimum

<b>∆</b>

to be reliable

Any

clinical

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<b>Sensitivity to Change after Fluid Bolus</b>

Echocardiography / Doppler

<b>Measurement Error </b>

=

<b>3 – 10%</b>

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We give the patient 10ml/kg of fluid

The patient responds to the fluid.

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<b>Starling Curves and Fluid Loading</b>

<b>Stroke </b>
<b>Volume</b>
<b>LVEDV</b>
Healthy
Mild
Heart
Failure
20%
8%
5%
2%

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So if the patient responded then

a second bolus will

<b>overload</b>

them!

If the patient was not responsive then

one bolus

<b>may not be enough loading</b>

!

So how did knowing that the patient was

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Maybe use a smaller challenge volume…

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<b>Starling Curves and Fluid Loading</b>

<b>Stroke </b>
<b>Volume</b>
<b>LVEDV</b>
Healthy
Heart
Failure
8%
~3%

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If the

<b>minimum detectable change </b>

is

<b>15% </b>

for BP / P

ulse

P

ressure

/ HR

there may be

<b>no detectable response</b>

even in a healthy patient!

And…

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“If the patient is fluid responsive

then we can give fluid…”

<b>But why?</b>

<b>Responsiveness</b>

is not the same as

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All of us in this room

<b>would respond </b>

to a fluid bolus…

but how many of us

<b>need</b>

one?

<b>None!</b>

Although one of these would be good…

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The reason we use a fluid bolus is…

To increase <b>Stroke Volume</b>

This leads to increased <b>Cardiac Output</b>

Which improves <b>Perfusion</b>

Which increases <b>Oxygen Delivery (DO₂)!</b>

<b>But does it?</b>

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We can define

<b>need</b>

easily:

It is the need for an increase in

tissue perfusion

and in

tissue oxygenation

(as measured by an increase in

tissue oxygen tension – PtO

₂

)

Does anybody measure PtO

₂

?

But what about

duration

30 mins

?

1 hour

?

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<b>DO</b>

<b>₂</b>

= 1.34 x [Hb] x SaO

₂

x CO

100

If fluid increases <b>CO</b> then this looks good but…

Fluid reduces haemoglobin concentration
which <b>reduces DO₂</b>.

1L of fluid reduces <b>[Hb] </b>by ~ <b>20%</b>.
But how much does <b>CO</b> increase?

If

<b>↑CO </b>

<20%

then we make a loss on the deal,

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The average increase in CO

in response to 1L of fluid is –

<b>11% </b>

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How many patients are fluid responsive?

Multiple (171) studies have consistently shown
only <b>50%</b> or less of haemodynamically

unstable patients are fluid responsive!

Therefore <b>50%</b> of patients given a fluid bolus
immediately have <b>reduced DO₂</b>,

i.e. they are directly harmed.

Of patients <i><b>who do respond </b></i>to fluid
only <b>50%</b> increase <b>CO</b> by <b>=>20%</b>

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<b>80%</b>

of a crytalloid bolus is

extravascular by

<b>60</b>

minutes…

And that’s on a good day!

CHEST 2015; 1 48 ( 4 ): 919- 926

(

<b>FACTT</b>

)

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<b>569</b> Fluid bolus doses in <b>127</b> patients
(for low BP, low urine output, or both)

Only <b>23%</b> of patients showed CO increase =><b>15%</b>

Mean increase in MAP at 1 hour = <b>2mmHg</b>
<b>No change </b>in urine output.

<b>94%</b> had <b>reduced tissue oxygenation </b>at <b>1 hour</b>.

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“Results show that volume expansion with crystalloids
in patients with circulatory shock has limited success

even in (volume) responders.”

<b>MAP increased by 2.9mmHg (3.9%)</b>

<b>[Hb] decreased from 95.9 g/L 91.1g/L (5%)</b>

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<b>Cardiac Index (L/min/m2_{) over 45 mins}</b>

“Responders” - <b>2.9 </b>L/min, <b>3.55</b> L/min, <b>3.1</b> L/min, <b>3.0 </b>L/min
Non-responders - <b>3.4 </b>L/min, <b>3.6</b> L/min, <b>3.3 </b>L/min, <b>3.2 </b>L/min

<b>0</b> <b>15</b> <b>30</b> <b>45 mins</b>

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<b>26</b> Post-op patients

<b>250ml</b> crystalloid rapidly

<b>50%</b> responders

Maximal <b>CO</b> at <b>1.2 minutes </b>post challenge

<b>CO</b> returned to baseline by <b>10 minutes</b>

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<b>Septic Shock Patients are </b>

<b>NOT</b>

<b>Volume Depleted </b>

(usually)

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The 7 questions we need to ask

<b>before</b>

giving an iv fluid bolus:

1. Is there clear evidence of inadequate tissue perfusion?

2. Is there clear evidence of inadequate preload?

3. Is it clear why preload is inadequate?

4. Is there evidence of impaired cardiac function?

5. Was there a positive response to PLR?

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<b>Conclusion:</b>

Taking all the research together, the number of
haemodynamically unstable patients treated with a

fluid bolus who still show an increase in DO₂ and
tissue oxygenation after 1 hour is…

<b>2.7%</b>

<b>Or about </b>

<b>1 in 36!</b>

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And our lucky patient today is…

<b># 17</b>

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But if anybody wants to know more about

fluid responsiveness then join me later and

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