This document summarizes a case study of a child with metabolic acidosis following sepsis and 20% body surface area burns. It applies the Fencl-Stewart approach to analyze the acid-base disturbance. This involves measuring the standard base excess, sodium-chloride effect, albumin effect, and calculating the unmeasured ion effect. In this case, the unmeasured ion effect of -21.5 mEq/L suggests lactic acidosis as the cause. Bicarbonate therapy is not recommended due to risks of worsening tissue hypoxia and intracellular acidosis. The appropriate treatment is to correct hypoalbuminemia, hypernatremia, and the underlying cause of lactic acidosis through improving oxygen delivery and

1. Fencl–Stewart approach: Telaah Kasus Gangguan Asam-Basa Kiki MK Samsi, dr.,Sp.A, M.Kes Pediatric Critical Care Unit Tarumanagara University - Sumber Waras Hospital

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4. Kasus 1 Seorang anak 2 thn, BB 10 kg: Ileus obstruktif Muntah-muntah Dehidrasi berat pH 7.6, Kalium 2 meq/L, Cl 82 meq/L Tatalaksana Pasang NGT untuk DEKOMPRESI Resusitasi cairan dengan RL Beri KCl untuk hipokalemia

5. Na + = 140 mEq/L Cl - = 82 mEq/L SID = 58 mEq/L OH - = 58 mEq/L Hypocloremic Alkalosis 58

6. The adverse effects of a severe alkalosis Decreased myocardial contractility Arrhythmias Decreased cerebral blood flow Confusion Mental obtundation Neuromuscular excitability Impaired peripheral oxygen unloading (due shift of oxygen dissociation curve to left).

8. The adverse effects of a severe alkalosis Hypoventilation (due respiratory response to metabolic alkalosis) Pulmonary microatelectasis (consequent on hypoventilation) Increased ventilation-perfusion mismatch (as alkalosis inhibits hypoxic pulmonary vasoconstriction).

9. Na + = 140 mEq/L Cl - = 82 mEq/L SID = 58 mEq/L OH - = 58 mEq/L + Hypocloremic Alkalosis Na + = 137 mEq/L Cl - = 109 mEq/L Lactat = 28 mEq/L SID = 0 mEq/L OH - = 0 mEq/L Ringer Lactat

10. Na + = (140 + 137 mEq/L) : 2 = 138,5 mEq/L Cl - = ( 82 + 109 mEq/L) : 2 = 95,5 mEq/L SID = 43 mEq/L OH - = 43 mEq/L 58 43

11. Na + = 140 mEq/L Cl - = 95 mEq/L SID = 45 mEq/L OH - = 45 mEq/L + Hypocloremic Acidosis Na + = 154 mEq/L Cl - = 154 mEq/L SID = 0 mEq/L OH - = 0 mEq/L NaCl 0,9%

12. Na + = (140 + 154 mEq/L) : 2 = 147 mEq/L Cl - = ( 82 + 154 mEq/L) : 2 = 118 mEq/L SID = 29 mEq/L OH - = 29 mEq/L 58 29

13. Kasus 2 Seorang anak 4 thn, BB 15 kg: Sepsis pasca luka bakar BSA 20% (1 minggu) Nafas cepat, febris Penurunan kesadaran AGD pH 7,2; PCO2 30 mmHg; PO2 80 mmHg BE – 2; SaO2: 92%

14. The major effects of a metabolic acidosis Depression of myocardial contractility Sympathetic overactivity (incl tachycardia, vasoconstriction, decreased arrhythmia threshold) Resistance to the effects of catecholamines Peripheral arteriolar vasodilatation Venoconstriction of peripheral veins Vasoconstriction of pulmonary arteries Shift of K+ out of cells -> hyperkalaemia

15. Terapi Resusitasi cairan RL disertai: Bicarbonat natrikus: Setuju atau Tidak Setuju Penderita kejang-kejang Hypocapnia

16. Recognised undesirable effects of bicarbonate administration Hypernatraemia Hyperosmolality Volume overload Rebound or ‘overshoot’ alkalosis Hypokalaemia Hypercapnia Impaired oxygen unloading due to left shift of the oxyhaemoglobin dissociation curve

17. Kasus 2 Elektrolit Natrium : 160 mEq/L Chlorida : 110 mEq/L Kalium : 3.5 Lab lain: Darah rutin dalam batas normal Protein total 4.0 Albumin 1.2 g/dL

18. Kasus 2 Stong Ion Difference =[Na + ]–[Cl – ] = 160-110 = 50 ALBUMIN EFFECT = albumin 1.2 g/dL = HIPOALBUMIN UNMEASURED ION EFFECT ???? As. Laktat akibat gangguan perfusi dan oksigenisasi

19. Clinical Investigations Strong ions, weak acids and base excess: a simplified Fencl–Stewart approach to clinical acid–base disorders D. A. Story*,1, H. Morimatsu2 and R. Bellomo2 British Journal of Anaesthesia, 2004, Vol. 92, No. 1 54-60

20. Four variables STANDARD BASE EXCESS (mmol /litre = meq / litre) from a blood gas machine SODIUM–CHLORIDE EFFECT (meq / litre) =[Na + ]–[Cl – ]–38 ALBUMIN EFFECT (meq/ litre) =0.25x[42–albumin (g/litre)] UNMEASURED ION EFFECT (meq / litre) = standard base excess–(sodium–chloride effect)– albumin effect

21. Kasus 2 STANDARD BASE EXCESS from a blood gas machine = -2 mEq/L SODIUM–CHLORIDE EFFECT (meq / litre) =[Na + ]–[Cl – ]–38 = 160-110-38 = 12 mEq/L ALBUMIN EFFECT (meq/ litre) = 0.25 x [42–albumin (g/litre)] = 0.25 x [42-12 g/L] = 7.5 mEq/L UNMEASURED ION EFFECT (meq / litre) = standard base excess–(sodium–chloride effect)– albumin effect = -2 – 12 – 7.5 = -21.5

23. TATALAKSANA KASUS 2 Untuk memperbaiki asidosis: perbaiki oksigenisasi jaringan Koreksi hypernatremia Koreksi hipoalbuminemia Na Bicarbonat ????

24. Important points about the use of bicarbonate in metabolic acidosis Ventilation must be adequate to eliminate the CO2 produced from bicarbonate Bicarbonate therapy can increase extracellular pH only if the CO2 produced can be removed by adequate ventilation. Indeed if hypercapnia occurs then as CO2 crosses cell membranes easily, intracellular pH may decrease even further with further deterioration of cellular function.

25. Important points about the use of bicarbonate in metabolic acidosis Bicarbonate may cause clinical deterioration if tissue hypoxia is present If tissue hypoxia is present, then the use of bicarbonate may be particularly disadvantageous due to increased lactate production (removal of acidotic inhibition of glycolysis) and the impairment of tissue oxygen unloading (left shift of ODC). This means that with lactic acidosis or cardiac arrest then BICARBONATE THERAPY MAY BE DANGEROUS.

26. Important points about the use of bicarbonate in metabolic acidosis Bicarbonate is probably not useful in most cases of high anion gap acidosis As mentioned above lactic acidosis can get worse if bicarbonate is given. Studies have shown no benefit from bicarbonate in diabetic ketoacidosis. In these cases, the only indication for bicarbonate use is for the emergency management of severe hyperkalaemia

27. Teng Kyu Natrium Cloride Albumin Unmessurement ion Lactat acid Phosphor +