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You are here: Home / 09. Medical/Surgical / metabolic-disorders / Alkalemia – Metabolic and Respiratory Alkalosis

Alkalemia – Metabolic and Respiratory Alkalosis

February 20, 2012 by CrashMaster

Alkalemia

hypokalemia (and sensitization to dig related arrhythmias)

reduction of ionized calcium leading to neurologic symptoms

Stimulates anaerobic metabolism

Metabolic Alkalosis

Plasma bicarb>45

seek to lower it to

  • Nasogastric Suction/Vomiting
  • Diuretics-from increased loss of urinary electrolytes and water. Cl loss balanced by reabsorbtion of bicarb, H+ moves into cells to allow eflux of K. Mg loss promotes loss of K
  • Hyperaldosteronism
  • Volume depletion: contraction alkalosis. Stimulation of renin-angiotensin to waste H+
  • Organic Ion administration-Lactate, acetate, and citrate. (need 8 units of blood to affect pH.)
  • Posthypercapnia-if chronic

Contraction alkalosis because relatively more bicarb in a smaller space (sketchy concept)

Patients need NaCl and Potassium Chloride

Can give hydrochloric acid

need 0.1 to 0.2 N solution (100 to 200 mmol per liter)

0.5 * kg * desired reduction in bicarb=mmol of acid needed

Volume in L of 0.1 M=desired mEQ/100 mEq/L

Using 0.2 desired mEq/200 mEq/L

Infuse at 0.2 mEq/kg/hour

 

Cl responsive if urine Cl is

Vomiting, gastric drainage, diuretics, lactate, acetate

 

Cl Resistant if Cl>20 mEq (Mineralcorticoid excess or K depletion)

excess mineralcorticoid (cushings, hyperaldo, ACTH tumors, licorice, renal art stenosis, steroids,)

severe k deficiency

mag deficiency

 

associated with high mortality (South Med J 1987;80(6):729)

3 Causes from a Renal Perspective

from Joel Topf

  1. Conditions with chloride depletion with secondary collecting duct hydrogen stimulation
  2. Conditions with primary stimulation of the collecting duct hydrogen secretion
  3. Increased Alakli Intake with renal failure

Respiratory alkalosis:

Acute

a.HCO3- drops 1 to 3.5 mEq/L for every 10 mm Hg drop in P CO2 .

Limit of compensation: bicarbonate is rarely below 18 mEq/L.

Chronic (renal compensation starts within 6 hours and is usually at a steady state by 1.5 to 2 days)

a.HCO3- drops 2 to 5 mEq/L for every 10 mm Hg drop in P CO2 .

Limit of compensation: bicarbonate is rarely below 12 to 14 mEq/L.

Pseudorespiratory Alkalosis

severely reduced pulmonary perfusion with normal alveolar ventilation (i.e. you’re bagging a shocked patient)

less CO2 is delivered and more CO2 is extracted (b/c of poor systemic perfusion and poor relative pulmonary perfusion respectively)

So get arterial eucapnia or even hypocapnia with a severely acidotic and hypercapnic venous and tissue state

 

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Filed Under: metabolic-disorders


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