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Sodium Bicarbonate Revisited

Acidosis is thought to have adverse physiological effects and generally is associated with increased mortality. Consequently, therapy to correct acidosis, usually with sodium bicarbonate is been widely used. In recent years, however, this approach is changing.

Disease process

Add acid

Loose alkali

acidosis Impaired acid excretion

More than 100 years of Soda Bi Carbonate

Adverse Effects Of Acidosis ………………. Depressed myocardial contractility Decreased catecholamine efficacy Arrhythmias Pulmonary vasoconstriction

Glycolytic enzyme phosphofructokinase

is pH dependent resulting in the impaired utilization of glucose

Below 7.o

Sodium Bicarbonate

Hypertonicity and hyperosmolality Hypercapnia and intracellular acidosis Ionized hypocalcaemia Decreased oxygen delivery Hypokalemia Increased organic acid production Rebound alkalosis Decreased VF threshold , arrhythmias Repeated doses : transient hypotension Intracellular acidosis / CSF acidosis Catecholamine inactivation Precipitation ( cal. carbonate ) Local infiltration necrosis

Hypertonicity and hyperosmolality

7.5 % sodium bicarbonate Sodium 0.9 mEq / ml Osmolality : 1700 mOsm /lit.

Normal serum osmolality is around 290

1700 / 6 = 284 , that’s why ideal dilution of S.B. should be 6 times and with 5 % dextrose

NaHCO3 Na + HCO3

H HCO3

H2O + CO2

Intracellular acidosis

60 mmHg

90 %

7.4

7.8

7.0

Impaired tissue oxygenation with correction of acidemia .

Hb. Sat.%

RT.

LT.

Oxyge

n delivery

24 to 48 hrs

Low 2-3 DPG levels Secondary to reduced glycolysis

Direct effect of pH on hemoglobin reducing affinity of oxygen

acute acidemia facilitates oxygen delivery, whereas more chronic acidemia hampers oxygen delivery.

Correcting acute acidemia could be more dangerous

Sodium Bicarbonate

Hypertonicity and hyperosmolality Hypercapnia and intracellular acidosis Ionized hypocalcaemia Decreased oxygen delivery Hypokalemia Rebound alkalosis Decreased VF threshold , arrhythmias Increased lactate production Repeated doses : transient hypotension Intracellular acidosis / CSF acidosis Catecholamine inactivation Precipitation ( cal carbonate ) Local infiltration necrosis

Case 1…………………

8 months old child with diarrhea and LRI is in shock His ABG is

pH 7.01

Pco2 36 HCO3 5.5

ACIDOSIS

LOW BICARB

BUT CO2 IS HIGH ?

WOULD BICARB BE INDICATED ? NO

Case 2.

Preterm weighing 1.8 kg was on oral feeds and developed Diarrhea , junior resident noted that the baby was moderately Dehydrated and had respiratory rate of 58 / min. Bolus of normal saline was given followed by a dose of bicarb , thinking that the baby may be acidotic. After about 4 hours baby had seizures . Sugar normal and so was calcium , seizure were controlled but recurred Again ……………….

Though the serum calcium was “normal ” These were hypocalcaemic seizures .

Ionic calcium low

CASE 3………….

DKA WITH RT LOWER LOBE CONSOLIDATION AND HYPOXIA

Ph 7.016 CO2 6 BICARB 6 PO2 58

Severe metabolic acidosis with mild hypoxia Sugar 689 , ketones ++++ , COMA

Received bicarb with other standard protocol for DKA……………sugar 326 mg %

Ph 7.36 CO2 34 BICARB 18 PO2 63

ABG LOOKS BETTER , MILD HYPOTENSION , ON SUPPORT SUGAR IS OK

Patient deteriorates soon for no obvious reason , his sugar is OK , ABG = Acidosis Anion gap still wide , ketones not very high

Ph 7.16 CO2 14 BICARB 9 PO2 57

8 HOURS AFTER

LACTIC ACIDOSIS

Rapid correction of acidosis shifts curve to left……..tissue hypoxia

Mild hypotension Diabetics have low 2.3. DPG Soda bicarb. promotes lactic acidosis

In severe DKA, bicarb therapy is not supported by the literature. In fact, at least 2 human studies have shown possible deleterious effects of bicarbonate administration even in patients with serum pH less than 7.0 . Thus the administration of sodium bicarbonate to patients with diabetic ketoacidosis cannot be recommended at any pH ( class 1 )

• Giving bicarbonate to a patient with a true

bicarbonate deficit is not controversial

• Controversy arises when the decrease in

bicarbonate concentration is the result of its

conversion to another base which, given time,

can be converted back to bicarbonate

What are the deleterious effects of acidemia ?

Is acidemia severe enough to warrant therapy ?

How much bicarbonate ?

what are deleterious effects of Bicarbonates ?

In considering acute bicarbonate replacement four questions should be thought of

SEVERE METABOLIC ACIDOSIS WITH ADEQUATE VENTILATORY SUPPORT HYPERKALEMIA HYPERMAGNESEMIA TRICYCLIC ANTI DEPRESSANT POISONING SODIUM CHANNEL BLOCKER POISONING

Indications as per A.H.A.

Sodium bicarbonate is further indicated in the treatment of certain drug intoxications, including barbiturates (where dissociation of the barbiturate-protein complex is desired), in poisoning by salicylates or methyl alcohol and in hemolytic reactions requiring alkalinization of the urine to diminish nephrotoxicity of hemoglobin and its breakdown products.

How do I give soda bicarb

×

Indication : if pH is less than 7.15 in DKA ( less than 7.1 and not improving ) HCO3 required = half of BW × ( 15 – HCO3 ) Dilute 4 to 6 times give over 2 hours Diluent : water for injection/5%dextrose

Ensure adequate ventilation

carbicarb, an equimolar mixture of sodium bicarbonate and sodium carbonate. Carbonate preferentially combines with hydrogen ions resulting in production of bicarbonate rather than CO2. Carbonate can also combine with carbonic acid, a reaction which also produces bicarbonate. Thus the acidosis is titrated without the production of CO2 or the lowering of intracellular pH.

ALTERNATIVE

Post resuscitation ..role of Soda Bicarbonate ?

I don’t have ABG facility and the patient is in shock

Should I give Soda Bicarbonate

Child with diarrhea and shock I would like to add S.B..

to normal saline bolus , comment

If the child admitted with me has received large dose of

S.B. what should I monitor ?

How do I dilute S.B., Rate of infusion

Role of S.B. in wide anion gap acidosis

Intratracheal administration for treatment of metabolic A

Can S.B. be used for treatment of hyponatremia ?

( equivalent to 6 % saline,7.5 % contains 0.9 mEq./ml)

FAQ,S ………………………….

OVERDOSAGE:

Should alkalosis result, the

bicarbonate should be stopped

and the patient managed

according to the degree of

alkalosis NORMAL SALINE may

be given, potassium chloride is

indicated if there is

hypokalemia. Severe alkalosis

may be accompanied by

hyperirritability or tetany and

these symptoms may be

controlled by calcium gluconate.

THANKS