急診高血鈉的處置

Hypernatremia from Sun YaiCheng

 

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

---