Background
Passive leg raising
What do we already know about the test?
Test | Advantages | Limitations | Confounding factors | Criterion of judgement | Diagnostic threshold | Level of evidence* |
---|---|---|---|---|---|---|
Passive leg raising | →Reversible, no fluid infusion | →Requires a direct estimation of CO/SV | →Possible false negatives in case of intra-abdominal hypertension →False negatives in case of venous compression stockings | ↗ CO | ≥ 10% | ++++ |
→Works regardless of breathing activity, cardiac rhythm, Vt, lung compliance | →False negatives in case of IAH | ↗ VTI | ≥ 10% | ++++ | ||
→Very well validated | ↗ end-tidal CO2 | ≥ 5% ≥ 2 mmHg | ++ | |||
↗ perfusion index | ≥ 9% | + | ||||
↘ PPV/SVV | ≥ − 1 to 4 points | + | ||||
↘ capillary refill time | ≥ − 27% | + | ||||
Mini-fluid challenge | →Easy to perform | →Requires a direct estimation of CO/SV | →Poor precision of the technique measuring cardiac output →Volume of fluid infused (minimum: 100 mL) | ↗ CO | ≥ 5% | ++ |
→Works regardless of breathing activity, cardiac rhythm, Vt, lung compliance, IAP | →Requires a precise estimation of CO/SV →Still requires fluid infusion | ↗ VTI | ≥ 10% | + | ||
Trendelenburg manoeuvre | →Reversible, no fluid infusion →Possible even in prone position, on the operating table or under ECMO →Works regardless of breathing activity, cardiac rhythm, Vt, lung compliance | →Possible gastric reflux →Requires more validation | →Intra-abdominal hypertension? | ↗ CO | ≥ 8 to 10% | + |
What's new?
Monitoring technique
Limitations
End-expiratory occlusion test
What do we already know about the test?
Test/index | Advantages | Limitations | Confounding factors | Criterion of judgement | Diagnostic threshold | Level of evidence |
---|---|---|---|---|---|---|
PPV | →Automatically measured →Widely available (invasive or non-invasive arterial pressure curve) →Requires no manoeuvre →Very well validated | →Impossible to use in many patients because of confounding factors | →False positives in case of cardiac arrhythmias, spontaneous breathing activity and possibly right ventricular failure →False negatives in case of low Vt, low lung compliance and IAH | Absolute value itself | ≥ 15% | ++++ |
SVV | →Automatically measured →Requires no manoeuvre →Well validated | →Impossible to use in many patients because of confounding factors →Requires a device for pulse contour analysis | →Those of PPV →An arterial pressure of poor quality may provide wrong values | Absolute value itself | ≥ 15% | +++ |
EEO test | →Easy to perform →Works regardless of breathing activity, cardiac rhythm, Vt, lung compliance →Well validated | →Requires a direct estimation of CO/SV →Requires mechanical ventilation →Cannot be used if the patient interrupts the 15-s EEO | →Interruption of the test before its end by breathing efforts of the patient | ↗ CO | ≥ 5% | +++ |
↗ VTI (better with additional EIO) | EEO alone: ≥ 5% EEO + EIO: ≥ 13% | + | ||||
↗ perfusion index | ≥ 2.5% | + | ||||
Vt challenge | →Requires no measurement in CO/SV (just an invasive or non-invasive arterial pressure curve) →Reliable in prone position and in spontaneously breathing patients | →Requires mechanical ventilation →Different diagnostic thresholds reported →Requires more validation | →Cardiac arrhythmias? →Intra-abdominal hypertension? | ↗ PPV | ≥ 1 to 3.5% | ++ |
Vena cava distensibility | →Requires no measurement in CO/SV | →False positives in case of spontaneous breathing activity and possibly right ventricular failure →False negatives in case of low Vt, low lung compliance →Quite low reliability →Not reliable in case of IAH →For SVC: requires TOE | →Those of PPV (except cardiac arrhythmia) | Absolute value itself | IVC: ≥ 12% SVC: ≥ 12 to 36% | + |
What's new?
Monitoring technique
Limitations
Pulse pressure and stroke volume variations
What do we already know about the indices?
What's new?
Limitations
Tidal volume challenge
What do we already know about the test?
What's new?
Respiratory variation in the diameter of the vena cava
What do we already know about the index?
What's new?
Reliability
Mini-fluid challenge
What do we already know about the test?
What's new?
Reliability
Monitoring technique
Limitations
Other tests
Other tests using the ventilator
Trendelenburg manoeuvre
Place of preload responsiveness assessment in patient management
No magic value!
Preload responsiveness: not always!
The presence of preload responsiveness does not mean that fluid should be infused
Testing preload responsiveness: which applications?T esting fluid responsiveness
Testing fluid responsiveness… and assessing the response to fluids
Any effect on patient outcome?
First author (year of publication) | Number of patients | Number of centres | Primary end-point | Effect of fluid administration* | Effect on mortality* | Other tested effects* | |||
---|---|---|---|---|---|---|---|---|---|
Chen [96] | 82 | 1 | Volume of fluids administered by days 3 and 5 and cumulative fluid balance by days 3 and 5 | Fluid balance at Day-3 | 1 952 [48–5003] mL vs 3 124 [767–10103] mL, p = 0.20 | In-hospital | 56% vs. 49%, p = 0.51 | Ventilator-free days | 5.5 [0–12.25] days vs 5.5 [0–16.75] days, p =0 .05 |
Need for renal replacement therapy | 41.5% vs 39.0%, p = 0.82 | ||||||||
Vasopressor-free days | 5.5 [0–10] days vs 5 [0–16] days, p = 0.84 | ||||||||
Richard [97] | 60 | 1 | Duration of cardiovascular failure | Daily volume of fluids for volume expansion | 383 (211 to 604) mL/day vs 917 (639 to 1,511) mL/day, p = 0.01 | 28-day | 23% vs. 47%, p = 0.10 | Time to shock resolution | 2.0 (1.2 to 3.1) days vs 2.3 (1.4 to 5.6) days, p = 0.29 |
Red cell transfusions | 103 (0 to 183) mL vs 178 (82 to 304) mL, p = 0.04 | ||||||||
Ventilator-free days | 14 [0–24] days vs 8 [0–21] days, p = 0.35 | ||||||||
Douglas [95] | 150 | 13 | Positive fluid balance at 72 h or ICU discharge | Fluid balance at 72 h or ICU discharge | 0.65 ± 2.85 L vs 2.02 ± 3.44 L, p = 0.02 | 30-day | 20% vs. 21%, p = 0.42 | Need for rate of renal replacement therapy | 5.1% vs 17.5%, p = 0.04 |
Need mechanical ventilation | 17.7% ± 34.1%, p = 0.04 |