Urinary alkalization and urinary acidification in poisoning

 

尿液鹼化原理是毒物從經由腎臟排除, 毒物為弱酸性的情況, 分佈於細胞外液並且protein binding不強. (像NSAID與protein binding強就無用)

 尿液鹼化適應症:

l  中重度salicylate毒性未達hemodialysis程度

(水楊酸中毒血液透析適應症: https://twmmhedpc.blogspot.com/2019/12/poison-hemodialysis-is-helpful.html

l  Phenobarbital (多劑量activated charcoal較優)[1].

 

l  Chlorophenoxy herbicides (2-4-dichlorophenoxyacetic acid and mecoprop): 須高尿流量 600 mL/h 較有效 [2, 3], forced diuresis 也是有幫忙的[4]

 

l  Chlorpropamide: supportive care/IV dextrose normally sufficient.

 

l  Toxicities of High-Dose Methotrexate [5]

 

尿液鹼化禁忌症

l  本來患者狀況fluid就overload

l  Renal impairment: CKD, uremia.

l  本來血鉀就很低(Uncorrected hypokalemia), 避免低血鉀引發VT [6] 最好keep 血鉀在4—4.5 mEq/L [7] 
 

尿液鹼化併發症:

l  Hypokalemia.

l  Volume overload.

l  鹼血症(Alkalemia);

l  輕度Hypocalcemia
 

尿液鹼化做法:

NaHCO₃^- 1 amp in N/S 1 BT run 125 ml, 有uremia, CHF, CKD 需調整滴速 [8]

1–2 mEq/kg IV bolus followed by 2 mEq/kg per h IV infusion

Sodium bicarbonate 4 amps in D5W 500ml run 250 mL/hr. (可以加20 mEq of potassium chloride避免低血鉀)

Keep urine output of 1 to 2 mL/kg per hour

 

尿液鹼化監測

urine pH 每 15 to 30分測尿的pH 保持7.5 to 8.5.

尿液鹼化曾用於Brazil 與 Iran的organophosphate poisoning 但並無有效實證。[9], 另抗發炎製劑Diflunisal和NSAID 也是無效 [10].

 

尿液酸化

urinary acidification 可以增加弱鹼的移除(包括 amphetamines和phencyclidine), 但產生的相關危險性(例如 rhabdomyolysis) 往往超過尿液酸化原本的好處.  

尿液酸化對MAOI的移除是無效的[4]

REFERENCES

 

[1]: Lindberg MC, Cunningham A, Lindberg NH. Acute phenobarbital intoxication. South Med J. 1992;85(8):803–807. doi:10.1097/00007611-199208000-00004

 

[2]: Bradberry SM, Proudfoot AT, Vale JA. Poisoning due to chlorophenoxy herbicides. Toxicol Rev. 2004;23(2):65–73. doi:10.2165/00139709-200423020-00001

 

[3]: Roberts DM, Buckley NA. Urinary alkalinisation for acute chlorophenoxy herbicide poisoning. Cochrane Database Syst Rev. 2007;(1):CD005488. Published 2007 Jan 24. doi: 10.1002/14651858.CD005488.pub2

 

[4]: Tintinalli’s Emergency Medicine, 8th ed. P.1227

 

[5]: Howard SC, McCormick J, Pui CH, Buddington RK, Harvey RD. Preventing and Managing Toxicities of High-Dose Methotrexate. Oncologist. 2016;21(12):1471–1482. doi:10.1634/theoncologist.2015-0164

 

[6] Tsai IH, Su YJ. Thyrotoxic periodic paralysis with ventricular tachycardia. J Electrocardiol. 2019; 54:93–95. doi: 10.1016/j.jelectrocard.2019.04.001

 

[7] Tintinalli’s Emergency Medicine, 8th ed. P.1268.

 

[8]. Table 176-2. Tintinalli’s Emergency Medicine, 8^th ed. P.1208 -1212.

 

[9]. Tintinalli’s Emergency Medicine, 8th ed. P.1320.

 

[10]: Balali-Mood M, Prescott LF. Failure of alkaline diuresis to enhance diflunisal elimination. Br J Clin Pharmacol. 1980;10(2):163–165. doi:10.1111/j.1365-2125. 1980.tb01734.x

 

 

-- edited 11th Jan, 2020 Yu-Jang Su.