Specimen Name Result Units Range
Plasma Sodium 141 mmol/L (135-145)
Potassium 3.8 mmol/L (3.5-5.5)
Chloride 101 mmol/L (100-109)
Anion Gap 12 mmol/L (7-17)
ABG pH 7.75 (7.36-7.44)
PaO2 110 mmHg (70-100)
PaCO2 24 mmHg (35-45)
HCO3- 32 mmol/L (21-26)
BE 13 mmol/L (±3)
Hb 109 g/L (120-180)
O2Hb 98 % (96-100)

34yo female admitted following drug O/D?
Salicylate Overdose
  • ingested 48g salicylate
  • marked respiratory alkalosis
  • added metabolic alkalosis - ??cause (Rx bicarbonate)

 

Mechanism:

  • inhibits many enzymes including:
    • cyclooxygenase - platelet > endothelial
    • oxidative phosphorylation
    • Kreb's cycle - succinate dehydrogenase, α-ketogluarate dehydrogenase
    • hyaluronidase
  • uncoupling in oxidative phosphorylation results in
    • ↑ heat production
    • ↑ glycogenolysis → early hyperglycaemia
    • ↑ energy requirement → late hypoglycaemia
    • ↑ lactate production, ↑ FFA's and ketogenesis → metabolic acidosis
  • central respiratory stimulation plus ↑ VO2/CO2 production
        → net respiratory alkalosis
  • toxicity and serum levels correlate poorly
    • maximal therapeutic doses ≈ 4-6g/d
    • toxic dose ≥ 10g
    • fatal doses ≥ 30g
  • dose-dependent kinetics
    • 300mg → 2.5hrs
    • 1000mg → 5-7hrs
    • 4000mg → 15-30hrs
  • small ↓pH (7.4→7.2) → ≈2x ↑ free fraction