Acid-Base Disorders

Volume Regulation Pharmacology

by Nnedimma Ozoani

Chapter 28 Diuretic Drugs

by Songyuan Ma

Diuretics

by Felicia MedStudent

pH > 7.45

Alkalemia

Respiratory

Hyperventilation

Secondary response:

Bicarb generation

Cellular buffering & Renal

Hepatic failure

Distress

Pregnancy

Pain

Anxiety

Hypoxemia

CNS lesions

Metabolic

Gain of bicarb or loss of H+

Secondary response:

Decreased ventilation

Cl- resistant

Stimulates Aldo

Severe hypokalemia

RAAS, Adrenal tumors

Cl- sensitive (volume depleters)

Vomiting

Loop, Thiazide Diuretics

Decreased ECV

Increased RAAS

Increased Aldo

Decreased H+, K+

pH < 7.35

Acidemia

PCO2

> 45

Compensatory response to respiratory acidosis

Causes

Miscellaneous

Obesity

Hypoventilation

Pulmonary

Parenchyma

Airway

Neuromuscular

Central

Anesthetics

Infection

Stroke

Compensatory Rate

4 Bicarb per 10 pCO2

Chronic Respiratory Acidosis (Single Disorder)

1 Bicarb per 10 pCO2

Compensation not as good: needs to regenerate bicarb

Acute Respiratory Acidosis (Single Disorder)

< 35

Compensatory response to metabolic acidosis

(Hyperventilation)

HCO3

> 28

Mixed

< 24

Metabolic Acidosis (Single)

Anion Gap

> (10-12)

High AG

Delta Ratio

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

1-2

Pure High AG Acidosis

High AG & Normal AG acidosis

<0.4

Hyperchloremic normal anion gap acidosis

Osmolar Gap

> (10-15)

Think ingestion

Propylene glycol

Ethylene glycol

Produces glycolic, oxalic acids

EtOH

Methanol

Methanol/formaldehyde intoxicatoin

Produces formic acid

Rx: Dialysis

10-15

MUDPILES

Salicylates

Also causes respiratory alkalosis (BRS phys)

Lactic acid

Hypoxia

Rx: Pressors

INH

TB Rx

Young women, Suicide

Paraldehyde

DKA

Acetoacetic acid

B-OH-butyric acid

Rx: Insulin

Uremia

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

GFR < 15-20

Rx: Dialyze

Malnutrition

10-12

Hyperchloremic

Urine anion gap

> -20

Renal

RTA of renal insufficiency

GFR usu. >15 ml/min

Hyperkalemic

Type 4 RTA

Hyporeninemic, hypoaldosteronemic distal RTA

Most common seen

Diabetic patients

You can generate a Type 4 RTA w/ drugs that limit Aldo fx on kidney

ACE

ARB

Aldo antagonists

Kidney for some reason doesn't respond to aldosterone

OR aldosterone effects on kidneys are being blocked (drugs)

Hypokalemic

NH4CL Admin.

No change in Urine pH

Classical distal RTA

Type 1 (only because it was discovered first)

Proton back leak distally

Amphotericin B (makes holes)

K+ leaks out (hypokalemic) to compensate

Urine pH < 5

Proximal RTA

Rare (Paraproteinemias --> Excessive amt of a single monoclonal gammaglobulin in the blood)

Waldenstrom's macroglobulinemia

Amyloidosis

Multiple myeloma

Abnormal protein damages the proximal tubule

Iatrogenic

CA inhibitors (Acetazolamide)

Gentamicin

Part of generalized disorder of proximal tubular function known as --> Fanconi syndrome

Self-limiting

Problem w/ Bicarb reabsorption --> Serum bicarb load delivered to kidney reduces, so kidney can handle new steady state due to distal effects

Aldosterone action leads to hypokalemia

HCO3 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

< -20

Extrarenal

Ext. loss of secretions in GI

Biliary

Pancreatic

Diarrhea

Acid-Base Disorders