FLUID STATUS REVIEW


A brief evidence based guide
- see fluid and electrolyte balance for a more comprehensive discussion


1. IS THIS PATIENT OVERLOADED?

A raised LV filling pressure signals the need for diuretics.
Small studies - more research needed to confirm conclusions.

1.  Review the History
Patients with no history of severe systolic dysfunction (reduced EF) have a low prevalence of increased filling pressure.
In patients with a history of severe systolic dysfunction, increased filling pressure is easier to confirm, but harder to exclude.
2.  Short of Breath?

Onset of dyspnoea and/or orthopnoea is somewhat helpful.

3.  Assess the Vital Signs.


Tachycardia, systolic hypotension and decreased pulse pressure are somewhat helpful.

4.  Look at the JVP.
Very helpful, but only useful when abnormal.
Points about JVP:

- Not visible in >16% (of critically ill patients), hard in short fat necks.
- Only accurate 56% of time - to improve: use R internal and a ruler, measure highest point.
- Normal is 0-4cm.
- Without a ruler, intra-observer measurements cannot be accurately compared, and people tend to underestimate.
- Abdominojugular reflux is specific for RVF but insensitive (if present, LR>6).  Press mid-abdo for 15-25s, pt mouth open & regular breaths (prevents valsalva), +ve if >=4cm sustained increase.
- Kausmall's sign (JVP paradoxically rises during inspiration) most often seen in severe RVF.

5.  Listen to the Heart.

A third heart sound (mid-diastolic) is somewhat helpful if heard.
Yeild doubled with bell over apex at 45 degrees in left lateral decubitus position, but overall not very helpful.

6.  Listen to the Lungs

Rales are somewhat helpful.

7.  Look for Oedema

Helpful, but only if present (specific, but not sensitive).

8.  If new patient - do a chest xray
Radiographic  redistribution is very helpful, but also only when present.
Cardiomegaly is helpful but only on the first assessment - thereafter loses specificity as does not fluctuate.
 


2. HAS THIS PT LOST A SIGNIFICANT AMT OF BLOOD?

History
A hx of maleana is not a useful gauge of severity of blood loss.

Vitals
Supine hypotension (<95) is helpful when present (often absent with blood loss <1150ml).
Supine tachycardia is helpful but only when present (often absent with blood loss <1150ml).
Supine bradycardia frequently occurs immediately after significant blood loss.

Postural Vitals
(Wait one minute after standing)
Mild postural dizziness has no value.
Severe postural dizziness (prevents standing) is very helpful.
Postural pulse increase of >30 is very helpful.
For large blood loss any one = sensitivity 97%, specificity 98%;
For moderate blood loss any one = sens only 22%.
Any one positive is also a useful marker of likely mortality from a GI bleed.
Postural BP loss of >20mmHg occurs in 11-30% normal over 65s and has little added value to the above.

Exam
Capillary refill is unhelpful.

Lab Tests
Admission haematocrit does not help gauge severity of blood loss.
(Often decrease is delayed 24-72 hrs).

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3. IS THIS PT HYPOVOLAEMIC?

For vomiting, diarrhoea, low oral intake etc.
Difficult to assess as there are few studies.

Talk to the Pt
Physical signs in the older pt of confusion, extremity weakness, nonfluent speech, dry mucous membranes, dry tongue, furrowed tongue, and sunken eyes are not useful in isolation.
However, they are useful in combination.
One study suggested pts with moderate or severe dehydration have 3.9 and 5.7 of these signs respectively, vs 1.3 for non-dehydrated patients.

Look at Vitals
Postural changes of BP are not significantly helpful.
Postural pulse increases should be just as helpful as for blood loss above.

Look at the Skin?
Skin turgor and capillary refill has no proven value.
Not having sunken eyes argues against.

Look in the Mouth
Only useful for ruling out.
Moist mucus membranes and tongue without a furrow makes dehydration unlikely.

Look at the JVP
If negative +ve LR of low CVP of 3.
If high, rules out hypovolaemia.
If normal, clinically useless.

Feel the axilla
If dry, positive LR 2.8.
If moist, negative LR 0.6.

Blood Tests
These are readily available, and hypernatraemia is very useful.
Have a low threshold for ordering this, urea, creatinine.

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Notes

If a patient has a raised filling pressure but aparantly normal ejective fraction, this reveals diastolic dysfunction.

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References

JAMA Rational Clinical Examination Series:

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