SALICYLATES (ASPIRIN, ASA)  

 

Overview:

  1. 1Salicylates  are found  in cold preparations, wintergreen, topical  keratolytics, Pepto - Bismol.
     
  2. >200 mg / kg  needed  to  produce  toxicity.
     
  3. Stimulates  respiratory center ®Respiratory alkalosis.
     
  4. Irritates  GI  mucosa ®N/V
     
  5. Enhances   lipolysis ® Ketosis
     
  6. Uncouples  oxidative  phosphorylation .  This  being  a  major  buffer  of  hydrogen  ion , its impairment  causes AG  metabolic  acidosis.
     
  7. Inhibits plt  aggregation®bleeding tendency

S & S:        

  1. CNS -  tinnitus, lethargy, coma due to cerebral edema.
     
  2. CV - complications  are  2ry  to  hypotension, arrhythmias 2ry  to decrease ATP and acidosis.
     
  3. Pulmonary  -  non-cardiogenic   edema, tachypnea, respiratory alkalosis
     
  4. GI  -  N/V, GI   bleed, Pilorospasm, AST/AGT
     
  5. Acid - base  -  > AG, Respiratory  alkalosis, low or high Na may be present, K.
     
  6. Metabolic  -  hyperpyrexia, low or high  Glucose, Ketosis  2ry  to  lypolisis.

DX:

  1. Bed side test with Ferric Chloride. This substance when  in contact with urine, turns violet color   if ASA is present. It doesn't specify if ingestion was acute or chronic.
     
  2. Serum  level  considered  to  be  toxic  when  >  100 mg / dL  of  acute and   >  60 mg / dL  of  chronic ingestion. Levels  usually  peak   after  6  hrs.,  but  due  to  possibility  of   enteric  coated  pills  or  pylorospasm, serial  levels  should  be  obtained. The level is then plotted on Done's nomogram.
     
  3. Done's  nomogram   is  useful  only  for  acute  single  ingestion . It  loses  it's  sensitivity   when :
     
    1. OD  after  24  hr.
    2. OD over 24 hr.
    3. Chronic  ASA  use
    4. Enteric coated ASA

Treatment:

  1. Fluid  and  lyte  replacement .  IVF  of  choice  is  D5 1/3  NS + 25 mEq  HC03  +  40 mEq KCl
     
  2. Decontamination   and  AC (multiple doses)
     
  3. Alkalinize  urine - done  with  100mEq  NaHCO3  in  1L  D51/4  NS .  Urine  should   be  frequently checked   to guarantee  pH >7.5  and  if  this  is  not  alkaline  serum  K  must  be  checked and corrected if low .
     
  4. Hemodialysis   -  done  when :  a) Renal  failure  b) ARDS  c) Severe  CNS  symptoms  d) Refractory  acidosis  e) Hepatic  compromise  with  ­  PT/PTT  f)  ASA  level  > 100 mg/dL  in acute or 60 mg/dL in chronic toxicity.

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