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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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What Are the Advantages?
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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What Are the Advantages?
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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