Fluid Challanged

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Fluid Challenge Revisited

Jean-Louis Vincent, MD, PhD, FCCM

Max Harry Weil, MD, PhD, ScD (Hon), FCCM

Crit Care Med 2006; 34:13331337

Presented by Resident Dr. Toh Han SiongSupervised by VS Dr. Hsiu-Nien Shen

Department of Intensive Care, Chi-Mei Medical Center, ROC, Taiwan

,


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Introduction

Acutely ill patients frequently require fluid repletion Hypovolemia: external loss & internal loss

Relative Hypovolemia: increases venous capacitance

Volume repletion may be essential Restore critical levels of cardiac output and arterial pressure

More normal perfusion of vital organs and tissues


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Introduction

Hemorrhage:

Benefit / risk of fluid repletion must be assessed

Benefits of delayed resuscitation Large volume of fluid red cell deficit oxygen deficit

Persistent hypovolemia will result in MODS

Fluid repletion is typically more effective duringhypovolemic states but is less effective in later stages.


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Introduction

A method forguiding volume repletion has beenavailable for 25 yrs based on measurements of the

patients response to a fluid load.

Current role of fluid challenge as a methodof assessing response to fluid infusion.


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In the absence of overt hypovolemia,

which patient is likely to respond favorably

to fluid administration?


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In the absence of overt hypovolemia, which patient is

likely to respond favorably to fluid administration?

Clinical examination: limited sensitivity & specificity History

Physical signs Routine laboratory tests

Any given level of filling pressure: more likely hypovolemia

more likely right / left heart failure

Neither is sufficiently reliable


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Extravascular volume deficits do not

become clinically apparent until they

exceed 10% of body weight.

Nonspecific sign

CO = SV x HR

Lack of reliability based on astatic measurement


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Dynamic Evaluation ?

Ambulatory patient

Sedated and paralyzed

Provocative test

Fluid is given overdefined interval

Effect on right-sided filling pressures


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Misconceptions 1

Fluid administration should be withheld

because the central venous pressure is high.

Any given level of filling pressure: not reliable !!!

Filling pressures may paradoxically decline during

volume repletion, presumably as a result ofdecreased sympathetic stimulation.


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Misconceptions 2

Fluid administration should be withheldbecause there is evidence of lung edema onthe chest roentgenogram.

Pulmonary edema Contraindication to fluids

Pulmonary edema Volume overload

May also be the cause ofhypovolemia ! Acute cardiogenic pulmonary edema

Extravasation of fluid into the interstitium and alveoli

Reduces plasma volume and total blood volume

Graded fluid administration reverse hypovolemia (shock)


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Misconceptions 3

Fluid administration should be withheldbecause the patient has already received alarge volume in a short time interval.

Was amount of fluid already given insufficient orexcessive?

The patients objective response to fluid administered over a

defined interval, representing the fluid challenge, rather

than quantity previously administered is likely to resolve this issue.


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Misconceptions 4

Tachycardia is due to fluid deficit and shouldprompt increases in fluid administration.

Tachycardia has diverse causes !!! Stress, high environmental temperatures, intrinsic heart

disease, effects of medications (esp. -agonists)

If there is a fluid deficit, prompt intervention isappropriate and the fluid challenge is likely toreduce the heart rate.


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Misconceptions 5

I gave fluids to increase the central venous pressureto 12 mm Hg to exclude an underlying hypovolemia.

NOT SO!

Variable zero reference, the effects of afterload, and increases inintrathoracic pressure (esp. positive pressure ventilation)

Relationships between intravascular volume and filling pressures

Intravascular volume may be insufficient or excessive !!!


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What is a Fluid Challenge?

Distinguished from conventional fluid administration

Fluid replacement to patients with cardiorespiratory failure

The fluid challenge is reserved forhemodynamicallyunstable patients and offers three major advantages:

1. Quantitation of the cardiovascular response duringvolume infusion.

1. Prompt correction of fluid deficits.

1. Minimizing the risk of fluid overload and its potentiallyadverse effects, especially on the lungs.


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What kind of Measurement

does it suppose?

Filling pressures Preload Net effect ofpreload, ventricular compliance, and afterload

Frank-Starling principle:

Fluid infusion SV filling pressure

Dual end points:

Filling pressures filling pressure levels at which stroke volumes are increased

Blood flow: related to arterial pressure & urine output vital organ blood flow is preserved


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Initial Fluid Challenge Technique

Weil and Henning, 1979: 25 rule for central venous pressure (CVP) 37 rule for pulmonary artery occlusion pressure (PAOP)

Filling pressure was measured at 10-min intervals

Change3mmHg for PAOP or 2 for CVP: infusion was continued

Change 37 mmHg for PAOP or 25 mmHg for CVP: infusion was interrupted and reevaluated after a 10-min wait

Change7mm Hg for PAOP or5 mmHg for CVP: infusion was stopped

The protocol may be updated and even simplified.


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Modified Fluid Challenge Technique

Type of Fluid

Rate of Fluid Administration

Goal to be Achieved

Safety Limits


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Type of Fluid

Crystalloids orColloids can be used

Fluid challenges with colloids allow formore rapid

completion of challenge.

Crystalloid: Physiologic (0.9%) salt solution (saline)

May increase serum chloride concentrations

Balanced salt solutions (Ringers lactate / Hartmanns solution) Mildly hypotonic, may exacerbate cerebral edema


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Type of Fluid

SAFE study: albumin vs crystalloid solution Mortality rate was identical

Hypoalbuminemia is associated with higher morbidity Vincent JL et al,Ann Surg2003; 237:319334: meta-analysis

Albumin administration may reduce complications in critically ill patients

SAFE trial: Improved survival with albumin in patients with sepsis who are often

hypoalbuminemia (relative risk of death, 0.87; 95% CI, 0.741.02;p 0.06)

Albumin may be beneficial in this subset of critically ill patients


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Type of Fluid

Synthetic colloid solution:

Hydroxyethyl starch solutions: Less expensive, adverse effects on blood clotting

Gelatins: Smaller MW, less effective plasma expanders, low cost


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Type of Fluid

No intravenous fluid solution that is ideal in all clinical settings No secure data support a preference for one over another

The choice is best made contingent on:

the underlying disease

the type of fluid that has been lost

the severity of circulatory failure

the serum albumin concentration of the patient

the risk of bleeding.


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Rate of Fluid Administration

Amount of fluid to be administered over a defined interval

Original fluid challenge technique: Infusion pump that allowed close control of the rate of infusion

Pump rate: 600 or 999 mL/hr

Guidelines of the Surviving Sepsis Campaign:

5001000 mL of crystalloids over 30 mins 300500 mL of colloids over 30 mins


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Goal to be Achieved

Identify and Quantitate primary defect

Defects that prompt the fluid challenge Hypotension & tachycardia: most common

Oliguria: organ perfusion Skin perfusion (esp. limbs): toe temperature, sublingual CO2

Lactate:

A good measure of Anaerobic metabolism Severity of perfusion failure

Fails to reverse rapidly enough to serve as a real-time indicator


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Safety Limits

Pulmonary edema due to congestive heart failure Most serious complication of fluid infusion PAOP is a more direct indicator than CVP Regard CVP as acceptable in patients who do not have intrinsic heart /

lung disease

Time interval for measurements of cardiac filling pressures Every 10 mins for a define fluid load of 100 or 200 mL

Availability of continuous and simultaneous infusion andmeasurements, the intervals may be extended (i.e., largervolumes with correspondingly larger intervals are possible).


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What Are the Advantages?

Proposed protocol: Concurrent measurement of monitoring MAP & HR, even CO

Safety limits based on filling pressures

Safety limit can be increased


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1. Quantitative goals & limits

Lets see what happens and call me if youre in doubt

Can be employed equally by experienced clinicians and trainees

Exposes mechanisms and, especially, limited cardiac competenceat one extreme and directs the clinician to search for causes of

perfusion failure other than hypovolemia on the other.

It supports the team approach. Physicians, and especially nurses, appreciate the clear end points.


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2. Fluid deficits are more rapidly corrected in contrast to

a protracted infusion over 12 or even 24 hrs, with lesser

durations of hypovolemia and, therefore, less ischemicinjury and multiple organ failure.

3. After goals are achieved, there is more predictable

completeness of fluid repletion. Fears of large

volumes are minimized.


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What Are the

Limitations and Risks? The technique identifies cardiac failure early, based on early

increases in filling pressures to threshold levels.

Failure of renal elimination of fluids: esp. resorption of edema Renal function is protected: fluid challenge restores hemodynamic stability.

If there is renal failure, we now have effective renal replacement therapies

Neurologically impaired patients in whom fluids may increaseintracranial pressure and adversely affect intracranial disease ortraumatic brain injuries or in patients with diabetes insipidus.


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Conclusion

Fluid challenge strategy: not new or complex bedside technique One of the most useful, basic interventions for management of critically ill

and injured patients

Updated protocol outlined above: Types of fluid selected

Rates of administration

Objective goals and limits for volumes and rates of infusion

A procedure that facilitates diagnosis in the routine managementof critically ill and injured patients


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Fluid Challanged