2013年3月31日 星期日

急診高血鈉的處置


Hypernatremia 定義:[Na+] > 150 mEq/L

Clinical Signs of Hypernatremic States Related to Serum Osmolality:

Osmolality (mOsm/kg) Manifestations

350–375                                    Restlessness, irritability
375–400                                    Tremulousness, ataxia
400–430                                    Hyperreflexia, twitching, spasticity
>430                                         Seizures and death



Causes of Hypernatremia *Likely or important ED diagnostic considerations.

Inadequate water intake*
  • Inability to obtain or swallow water
  • Impaired thirst drive
  • Increased insensible loss
Excessive sodium
  • Iatrogenic sodium administration  
Sodium bicarbonate
Hypertonic saline
  • Accidental/deliberate ingestion of large quantities of sodium  
Substitution of salt for sugar in infant formula or tube feedings
Salt water ingestion or drowning
  • Mineralocorticoid or glucocorticoid excess*  
Primary aldosteronism
Cushing syndrome
Ectopic ACTH production
  • Peritoneal dialysis  
Loss of water in excess of sodium
GI loss*  
  • Vomiting, diarrhea, intestinal fistula
Renal loss  
  • Central diabetes insipidus  
  • Impaired renal concentrating ability  
  • Osmotic diuresis (multiple causes)*     
Hypercalcemia
Decreased protein intake
Prolonged, excessive water intake
Sickle cell disease
Multiple myeloma
Amyloidosis
Sarcoidosis
Sjögren syndrome
Nephrogenic diabetes insipidus
Congenital
Drugs/medications
  • Alcohol, lithium, phenytoin, propoxyphene, sulfonylureas, amphotericin, colchicine
Skin loss  
  • Burns, sweating
Essential hypernatremia


急診病人高血鈉最常見的原因是「嚴重水分不足 severe volume loss」

    Treatment
    1. The cornerstone of treatment is volume repletion.
    2. Volume should be replaced first with NS or lactated Ringer's solution.
    3. Some practitioners inappropriately fear using NS solution from concern that an [Na+] of 154 mEq/L exceeds normal serum [Na+]. However, in most hypernatremic states, there is a total body [Na+] deficit, and the use of NS allows a more gradual decrease in serum [Na+].
    4. Once perfusion has been established, the solution should be converted to 0.45% saline or another hypotonic solution until the urine output is at least 0.5 mL/kg/h.
    5. The reduction in [Na+] should not exceed 10~15 mEq/L per day.
    • 原則:先處理水分缺損,再來矯正高血鈉
    • 輸液選擇:先以 N/S 矯正水分缺損後,再用 half saline or D5W 矯正高血鈉
    • 血鈉變化應每天小於 10~15 mEq/L

      Free Water Deficit 計算

      公式一 (Washington manual)

      公式二 (Harrison, ICU Book,Tintinalli, Rosen )
      Free Water Deficit
      Replacement Volume = TBW deficit × 1/(1-X)
      X= [Na+] of resuscitation fluid / [Na+] of isotonic saline


      70 公斤的成人,抽血發現 [Na+] 160 mEq/L
      計算式:
      TBW deficit = 0.6 ×70× [160/140-1]= 6 L
      若使用 0.45NaCl 做為輸液
      Replacement volume = 6 × 1/ (1-½)=12 L
      水分缺損要在 48小時 補足
      點滴速度約每小時 250 mL

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