Acid-Base Disorders

pH < 7.35

r

Acidemia

PCO2

< 35

r

Compensatory response to metabolic acidosis(Hyperventilation)

HCO3

< 24

Metabolic Acidosis (Single)

Anion Gap

10-12

Hyperchloremic

Urine anion gap

< -20

r

Extrarenal

Diarrhea

Ext. loss of secretions in GI

Pancreatic

Biliary

> -20

r

Renal

Hypokalemic

NH4CL Admin.

Urine pH < 5

Proximal RTA

r

Rare (Paraproteinemias --> Excessive amt of a single monoclonal gammaglobulin in the blood)Waldenstrom's macroglobulinemiaAmyloidosisMultiple myelomaAbnormal protein damages the proximal tubuleIatrogenicCA inhibitors (Acetazolamide)GentamicinPart of generalized disorder of proximal tubular function known as --> Fanconi syndromeSelf-limitingProblem w/ Bicarb reabsorption --> Serum bicarb load delivered to kidney reduces, so kidney can handle new steady state due to distal effectsAldosterone action leads to hypokalemiaHCO3 not reabsorbed --> Na+ travels with it --> juxtaglomerular apparatus senses sodium load passing through --> secretes renin --> Angiotensinogen to Angiotensin I (by renin)--> AgI to AgII (by ACE) --> Vasoconstriction + Aldosterone stimulation --> sodium intake distally, potassium excreted --> hypokalemia

No change in Urine pH

Classical distal RTA

r

Type 1 (only because it was discovered first)Proton back leak distallyAmphotericin B (makes holes)K+ leaks out (hypokalemic) to compensate

Hyperkalemic

Type 4 RTA

r

Hyporeninemic, hypoaldosteronemic distal RTAMost common seenDiabetic patientsYou can generate a Type 4 RTA w/ drugs that limit Aldo fx on kidneyACEARBAldo antagonistsKidney for some reason doesn't respond to aldosteroneOR aldosterone effects on kidneys are being blocked (drugs)

RTA of renal insufficiency

r

GFR usu. >15 ml/min

> (10-12)

High AG

Delta Ratio

Osmolar Gap

10-15

MUDPILES

Malnutrition

Uremia

r

Typically doesn't get that high because we dialyze before they get that sick.

Rx: Dialyze

GFR < 15-20

DKA

Rx: Insulin

B-OH-butyric acid

Acetoacetic acid

Paraldehyde

INH

r

TB Rx

Young women, Suicide

Lactic acid

Rx: Pressors

Hypoxia

Salicylates

r

Also causes respiratory alkalosis (BRS phys)

> (10-15)

r

Think ingestion

Methanol

r

Methanol/formaldehyde intoxicatoin

Rx: Dialysis

Produces formic acid

EtOH

Ethylene glycol

Produces glycolic, oxalic acids

Propylene glycol

<0.4

Hyperchloremic normal anion gap acidosis

<1

High AG & Normal AG acidosis

1-2

Pure High AG Acidosis

>3

High AG + concurrent met. alk or pre-existing comp. resp acid

> 28

Mixed

> 45

HCO3

< 24

Mixed

> 28

r

Compensatory response to respiratory acidosis

Compensatory Rate

1 Bicarb per 10 pCO2

r

Compensation not as good: needs to regenerate bicarb

Acute Respiratory Acidosis (Single Disorder)

4 Bicarb per 10 pCO2

Chronic Respiratory Acidosis (Single Disorder)

Causes

Central

Stroke

Infection

Anesthetics

Neuromuscular

Pulmonary

Airway

Parenchyma

Miscellaneous

Hypoventilation

Obesity

pH > 7.45

r

Alkalemia

Metabolic

r

Gain of bicarb or loss of H+Secondary response:Decreased ventilation

Cl- sensitive (volume depleters)

Loop, Thiazide Diuretics

Decreased ECV

Increased RAAS

Increased Aldo

Decreased H+, K+

Vomiting

Cl- resistant

Stimulates Aldo

RAAS, Adrenal tumors

Severe hypokalemia

Respiratory

r

HyperventilationSecondary response:Bicarb generationCellular buffering & Renal

CNS lesions

Distress

Hypoxemia

Anxiety

Pain

Pregnancy

Salicylates

Hepatic failure