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

fluid bolus who still show an increase in DO 2 and tissue oxygenation after 1 hour is…. 2.7%[r]

IV Fluid –

Where Will It Be One Hour From Now?

Professor Brendan Smith

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

Choose a number between and 36. Remember your number…

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

But does it have to be intravenous fluid?

What about oral

Dr Thomas Latta – Scotland – 1832

(Cholera epidemic)

1 ounce = 30ml

Dr Thomas Latta – Scotland – 1832

(Cholera epidemic)

1 ounce = 30ml

Six pints = 3.4 litres

How did we get from small volumes of fluid to 8, 10, 15+ litres?

The average volume of blood in an adult

= litres

The average plasma volume

= Litres

Even if there was no plasma left, why would we ever need more than

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

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

Bryan Cotton, Shock 2006; 26 (2): 115 - 121

“If giving 1 or 2 (or 3 or 4) litres of normal saline doesn’t result in a sustained increase in BP or oxygen

delivery, why would the 5th or 6th

litre give you a different result?”

The “Fluid

The curse of “fluid responsiveness”

The curse of “fluid responsiveness”

Insert Vietnamese translation here

Insert Vietnamese translation here

Insert Vienamese translation here

The curse of “fluid responsiveness”

The curse of “fluid responsiveness”

Are you going to give

500ml of crystalloid in 10 minutes

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 at least 30%

Can you measure a hair accurately using a ruler?

Sensitivity to Change

Would you dose medication using these scales?

Sensitivity to Change after Fluid Bolus BP

Pulse Pressure

(BPsystolic – BPdiastolic)

Heart Rate

What about Cardiac Output and Stroke Volume?

Measurement Error of Methods

Swan-Ganz 20 - 30%

PiCCO 20 - 40%

NiCOM (Cheetah) 25 - 45%

ICG 30 - 70%

15% minimum ∆ to be reliable

Any clinical

Sensitivity to Change after Fluid Bolus Echocardiography / Doppler

Measurement Error = 3 – 10%

We give the patient 10ml/kg of fluid

The patient responds to the fluid.

Starling Curves and Fluid Loading Stroke Volume LVEDV Healthy Mild Heart Failure 20% 8% 5% 2%

So if the patient responded then a second bolus will overload them!

If the patient was not responsive then one bolus may not be enough loading!

So how did knowing that the patient was

Maybe use a smaller challenge volume…

Starling Curves and Fluid Loading Stroke Volume LVEDV Healthy Heart Failure 8% ~3%

If the minimum detectable change is 15%

for BP / PulsePressure / HR

there may be no detectable response

even in a healthy patient! And…

“If the patient is fluid responsive then we can give fluid…”

But why?

Responsiveness

is not the same as

All of us in this room would respond

to a fluid bolus…

but how many of us need one?

None!

Although one of these would be good…

The reason we use a fluid bolus is…

To increase Stroke Volume

This leads to increased Cardiac Output

Which improves Perfusion

Which increases Oxygen Delivery (DO2)!

But does it?

We can define need easily: It is the need for an increase in

tissue perfusion and in

tissue oxygenation

(as measured by an increase in

tissue oxygen tension – PtO2) Does anybody measure PtO2?

But what about duration 30 mins?

1 hour?

DO2 = 1.34 x [Hb] x SaO2 x CO 100

If fluid increases CO then this looks good but…

Fluid reduces haemoglobin concentration which reduces DO2

1L of fluid reduces [Hb] by ~ 20% But how much does CO increase?

If ↑CO <20% then we make a loss on the deal,

The average increase in CO in response to 1L of fluid is –

11%

How many patients are fluid responsive?

Multiple (171) studies have consistently shown only 50% or less of haemodynamically

unstable patients are fluid responsive!

Therefore 50% of patients given a fluid bolus immediately have reduced DO2,

i.e they are directly harmed

Of patients who respond to fluid only 50% increase CO by =>20%

80% of a crytalloid bolus is extravascular by 60 minutes…

And that’s on a good day!

CHEST 2015; 48 ( ): 919- 926

(FACTT)

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

Only 23% of patients showed CO increase =>15%

Mean increase in MAP at hour = 2mmHg No change in urine output

94% had reduced tissue oxygenation at 1 hour

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

even in (volume) responders.”

MAP increased by 2.9mmHg (3.9%)

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

Cardiac Index (L/min/m2) over 45 mins

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

0 15 30 45 mins

26 Post-op patients

250ml crystalloid rapidly

50% responders

Maximal CO at 1.2 minutes post challenge

CO returned to baseline by 10 minutes

Septic Shock Patients are NOT Volume Depleted

(usually)

The questions we need to ask

before 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?

Conclusion:

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 hour is…

2.7%

Or about 1 in 36!

And our lucky patient today is…

# 17

But if anybody wants to know more about fluid responsiveness then join me later and