Nov 2006 Kishore P.Critical Care Conference

Fluids and electrolytes

Nov 2006 Kishore P.Critical Care Conference

Case 1

• 23 yr old girl presented with 5 days of fever, cough, chest pain and breathlessness. She was intubated for progressive hypoxia and shifted to the ICU. On arrival in the ICU, she was maintaining peripheral saturation of 91% with FiO2 of 100/8. Her heart rate was 140/min, resp rate was 40/min and BP 90/50mmHg with warm peripheries. The X-Ray shows bilateral infiltrates, most in the right lower zone. A diagnosis of bacterial pneumonia with sepsis was made and she was started on Antibiotics. Her blood pressure dropped to 50 systolic over the next hour.

Nov 2006 Kishore P.Critical Care Conference

A central line was inserted and the CVP was found to be 4mmHg. 1 liter of colloid was rushed in after which the CVP became 14mmHg and she was started on Noradrenaline and subsequently on dopamine infusions. Her blood pressure came up with this but she continued to need frequent fluid bolus resuscitations to maintain BP even though the CVP was high over the next 3 days. She gradually improved over the next few days, becoming afebrile and requiring lower doses of inotropes. Her ventilatory requirements diminished and she was considered for weaning.

Nov 2006 Kishore P.Critical Care Conference

• However oxygen requirements went up to 80/8 and she failed 2 attempts at weaning. X-Rays showed bilateral interstitial shadows.

• Hb: 7gm%• TC: 8900/cumm• Na- 136• K-3.8• Creat: 0.6mg%• Ca: 7.0mg%• PO4: 2.5mg%

• TP: 4.5gm%• Alb: 1.6gm%• At day 10,

cumulative balance: +16875ml

Nov 2006 Kishore P.Critical Care Conference

• She was given 10mg of inj. Frusemide and put on an IV infusion of the same at 2mg/hour. 4 hours later, her blood pressure fell, necessitating stopping of the Frusemide infusion and fluid bolus resuscitation.

Nov 2006 Kishore P.Critical Care Conference

• Colloid Vs crystalloid.• Is CVP an accurate measure of

intravascular volume status?• How much fluid is enough?• Why wasn’t this patient weanable-the

“ebb and flow of shock”• Fluids and the lung-the importance of the

cumulative balance.• Why is it difficult to mobilize fluid?• The rationale for a “routine” fluid order.

Nov 2006 Kishore P.Critical Care Conference

Crystalloid Vs. Colloid

• No difference in clinical end points• Volume of colloid required is less-

faster administration• Colloid expensive• Total dose of colloid limited in renal

failure

Nov 2006 Kishore P.Critical Care Conference

Is CVP a good measure

• Correlation with intravascular volume very poor

• Easiest objective measurement• Other clinical markers of volume-skin

turgor, urine output, PF ratio, serum sodium must be correlated

• The leg raise test

Nov 2006 Kishore P.Critical Care Conference

Seven times?

• No, seventy times seven!• Fill to perfusion targets• Don’t go by the numbers

Nov 2006 Kishore P.Critical Care Conference

Ebb and flow of shock

• In the initial days of shock, there is intense sodium and water avidity

• Patients need large amounts of fluids• Once the pathology is in resolution,

patients go into a diuretic phase and put out all the resuscitation fluid

• This may not happen for some reasons-– Decreased oncotic pressure– Decreased renal function

Nov 2006 Kishore P.Critical Care Conference

The lung and fluid

• Fluid preferentially sequesters in the lung• One of the earliest signs of a fluid overload

is a drop in the P/F ratio• Hence an unrecognised waterlogged state

is to be ruled out in all patients with unexplained hypoxia and failed weaning

• The cumulative balance sheet is a useful adjunct for fluid management in the ICU.

• +1000ml /day for the first 2 days of ventilation and +500ml/day subsequently

Nov 2006 Kishore P.Critical Care Conference

Why difficult to mobilise?

• 2 common reasons:– Decreased oncotic pressure-

hypoalbuminemia– Decreased renal function

• Blood/albumin with frusemide infusion

• Dialysis

Nov 2006 Kishore P.Critical Care Conference

Routine fluids

• Maintenance need for water-50ml/kg• Daily need for Na-10g. Each bottle of

DNS/NS contains 4.5g• Minimum calories required to prevent

infection -6kcal/kg. i.e. 300-400kcal• Hence 2 bottles of DNS and 3 bottles of D5

will fulfill all the above requirements• Potassium requirement is 3-4.5gm/day• 50%MgSO4 2ml can be added as

maintenance to the IVF

Nov 2006 Kishore P.Critical Care Conference

• Volume-give more if there are ongoing losses. Restrict in heart, renal failure or if oxygenation poor

• If fluid restricted, use 10% dextrose to ensure minimum caloric requirement is met

• Potassium according to daily serum values. No added Potassium or Magnesium in renal failure

• Number of sodium containing bottles can be adjusted according to the daily serum sodium values

Nov 2006 Kishore P.Critical Care Conference

• Be strict with fluid balance only if it affects oxygenation

• Use frusemide infusion with fluid restriction

• Remember, CVP by itself is not a clinical target

Nov 2006 Kishore P.Critical Care Conference

Signs of fluid overload

• CVP>15cmH2O• Worsening P/F ratio• Bilateral crackles• LVS3• Bilateral X-Ray infiltrates• VPW>70mm with a CTR>0.55• Rapid improvement (<24hrs) in

oxygenation with fluid removal

Nov 2006 Kishore P.Critical Care Conference

Signs of fluid depletion

• CVP<5cmH2O• MAP<70mmHg, HR>100/min• Serum sodium>145 MEq/L• Urea: creatinine ratio> 40:1• Decreased skin turgor

Nov 2006 Kishore P.Critical Care Conference

Electrolyte management

• Hyponatremia• Hypernatremia• hypokalemia• Hyperkalemia• Phosphate• Calcium• Magnesium