Parenteral Fluid Therapy in Stroke Patient

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Introduction

Adequate  fluid  intakes  must  be  ensured  in  stroke patients at risk of dehydration, especially in the presence of  dysphagia and reduced consciousness(1,5) Monitoring and attempting to stabilize acute physiological parameters within normal limits such as blood pressure, temperature,   hydration   status,   glucose   levels   and oxygen saturation has become standard practice for some acute stroke units(1)

Parenteral fluids may have reduced the occurrence of dehydration  and  maintained  systemic  blood  pressure after  acute  stroke.(2)   Selection  of  initiating  solutions during acute phase has been decided arbitrarily owing to the fact that studies of electrolyte imbalance after stroke are not extensive, and it remains unclear whether initial hydration status influences mortality or functional recovery. As a rule,  rehydration with 5% dextrose or hypotonic solutions during the first hours is not justifiable since it will readily enter the brain cells resulting in worsening of brain edema. The American Heart Association has recommended normal saline at 50 ml/hour during the first hours of acute ischemic stroke(3).

However, it is not stated clearly when one has to switch to maintenance solution. Anaerobic metabolism initiated by ischemia induces local lactic acidosis and elevated tissue PCO2 (not necessarily systemic lactic acidosis)(4). This fact has caused many authorities to decline the use of lactated Ringer’s solution as ‘resuscitating ‘ solution in acute stroke. Secondly, the osmolarity of lactated Ringer i.e. 273 is considered hypotonic to plasma (normally 285 + 5 mOsm/L). Since there has been no standard fluid regimen, neurologists may either use normal saline, Ringer’s solution or even some doctors use Ringer’s lactate  in  spite  of  the  concern.  The  proponents  of Ringer’s solution  may either think that the osmolarity of Ringer’s solution (310 mOsm/L) is ideal in preventing edema , or thought wrongly that Ringer’ solution is the same as Ringer’s lactate minus lactate. In fact, their sodium and chloride contents differ significantly(6).

	Glu	Electrolyte(mEq/L)
Product	Glu (g/L)	Na+	K+	Ca++	Cl-	Lact ate	Acet ate	(mO sm/ L)
Normal saline	-	154	-	-	154	-	-	308
Ringer’s solution	-	147	4	4,5	155. 5	-	-	310
Lactated Ringer (RL)	-	130	4	3	109	28	-	273
Asering (acetated Ringer)	-	130	4	3	109	-	28	273
KAEN 3B	27	50	20	-	50	20	-	290
KAEN 3A	27	60	10	-	50	20	-	290

Within the context of fluid resuscitation in hypovolemic shock, the prolonged use of normal saline and Ringer’s solution is associated with increased risk of hyperchloremic dilutional acidosis. In head injuries or subarachnoid hemorrhage, the use of normal saline and Ringer’s solution may be suitable in view of   high incidence of electrolyte imbalances, particularly hyponatremia. Any intracranial disease, surgery, mechanical ventilation and anesthetics may be complicated with electrolyte imbalance. Two distinct entities exist, namely cerebral salt wasting and SIADH.

The former is truly sodium depletion and although the clinical picture is similar to latter, this condition (CSWS) requires  different  approach of  management by  which high sodium infusion solution is warranted(7) On the contrary SIADH   responds merely to fluid restriction in the region of 600-800 ml/day. However, this is not possible in critically ill who may require minimum fluid load more than this to maintain cerebral perfusion pressure.

These two conditions are the suitable indications for normal saline and Ringer solution.

However, it remains to be questionable if normal saline or Ringer’s solution are suitable as maintenance solution in acute ischemic stroke. One should also consider that spurious hyponatremia may be caused by tremendous hyperglycemic response during acute phase.

Each 100 mg/dl increase of glucose concentration is associated with reduction of  1.7 mEq/L of sodium. In addition, plasma osmolarity is also important factor.

One recent study has shown that the raised plasma osmolarity during admission is associated with stroke mortality.  Plasma  osmolarity  >296  is  considered indicative of hyperosmolar state. This study however did not show the influence of intravenous rehydration, unlike beneficial oral rehydration on clinical outcome(2) (note: type of infusion solution was not mentioned explicitly).

Ringer’s acetate may be a suitable alternative to normal saline and Ringer’s solution.

LR and AR differ only in their bicarbonate source. LR contains 28 mmol of lactate per liter while AR has 28 mmol of acetate. Unlike lactate the metabolism of which takes place mostly in the liver, acetate is metabolized mainly in muscles and to a lesser extent in kidneys and heart. Acetate Ringer’s solution has become a standard resuscitation fluid in pediatric diabetic ketoacidosis, and proved to be a better intraoperative solution than LR in maintaining core temperature during iso- and sevofluran anesthesia(8,9,10) .

The issue of osmolarity can be solved by addition of 20%  or  40%  magnesium  sulphate.  For  example,  to render the osmolarity of  Ringer’s acetate to 290, add 10 ml of 20% MgSO4. Administration of MgSO4  is at least safe in stroke patients.(11)

Current Osmolarity of Asering (Ringer’s acetate)	Desired osmola- rity	ml of 20% MgSO4 to be added	Mg (mEq /cc)	Magnesium (total)
273.4 273.4 273.4 273.4	285 290 295 300	7.25 10.375 13.5 16.625	1.66 mEq/ cc	12 mEq 17 mEq 22.41 mEq 27.5 mEq

Once the hemodynamic condition has been stabilized, maintenance fluid therapy can be given as KAEN 3B/KAEN 3A. These two solutions may offer advantages in hypertonic dehydration as well as providing daily homeostasis requirement of potassium and sodium. There has been increasing evidence a high potassium intake caused a large reduction in deaths from stroke even when blood pressure was precisely matched between those on the high and low potassium intakes(12).

CONCLUSION:

Neurologists should not underestimate the importance of hydration status of stroke patients. One particular theme that has emerged from stroke unit trials is that there are differences in the way acute physiology (such as temperature, blood pressure, blood glucose    and hydration) are managed between these units and nonstroke units.

There are different approaches of rehydrating  patients with ischemic stroke from those with SAH, head injuries or neurosurgeries.

Timing and selection of parenteral fluids may need to be revisited. One good candidate for initiating solution in acute ischemic stroke  is Ringer’s acetate. Unlike normal saline or Ringer solution, it is not associated with increased risk of hyperchloremic dilutional acidosis when given aggressively in correcting dehydration and shock. Secondly, it does not interfere with the interpretation of focal (tissue) lactic acidosis. Should there be a desire to approximate the osmolarity of Ringer’s acetate to that of plasma, addition of 20% magnesium sulfate is enabled in view of its established safety, while there is now ongoing large scale efficacy study involving 712 patients. Following acute phase of stroke, maintenance solution can be considered to keep the electrolyte homeostasis, particularly potassium and sodium.

REFERENCES

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2. Bhalla A. et al. Influence of Raised Plasma Osmolality on clinical outcome after acute stroke. Stroke. 2000;31:2043- 2048
3. Adams HP et al. Guidelines for the Early Management of Adults With Ischemic Stroke Stroke 2007, 38:1655-1711
4. William E. Hoffman, Fady T. Charbel,, Guy Edelman, James I. Ausman, Brain tissue acid-base changes during ischemia Neurosurgical Focus 2(5): Article 2, 1997
5. Whelan K. Inadequate fluid intakes in dysphagic acute stroke.Clin Nutr 2001 Oct;20(5):423-8
6. Pedoman Cairan Infus PT Otsuka Indonesia 2000
7. Springate J. Cerebral Salt-Wasting Syndrome. eMedicine Journal, may 2, 2001 Vol 2 No 5
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9. Kashimoto S. Comparative effects of Ringer’s acetate and lactate solutions on intraoperative central and peripheral temperatures. J Clin Anesth1998;10(1):23-27
10. Mark A Graber. Terapi Cairan, Elektrolit dan Metabolik. Farmedia. Edisi 3, 2010
11. Keith W. Muir, Keneddy R. Lees. Dose Optimization of Intravenous Magnesium Sulfate. (stroke.1998;29:918- 923).
12. Feng J He, Graham A MacGregor, Beneficial effects of potassium BMJ 2001;323:497-501 ( 1 September )