Acid Base Disorders

Normal pH?

7.4

Normal PCO2?

40 mmHg

Normal HCO3-

24 mEq/L

What is PaCO2?

is the partial pressure of CO 2 in arterial blood (35-45 mmHg)

How is HCO3- measured?

Indirectly on ABG

How is CO2 measured?

on a venous draw (e.g. BMP, CMP) is also equivalent to

bicarbonate concentration

Respiratory acidosis?

Decrease pH, increased pCO2 and HCO3

Metabolic acidosis?

Decrease pH, decreased pCO2 and HCO3

Respiratory alkalosis?

Increased pH, decreased pCO2 and HCO3

Metabolic alkalosis?

Increased PH, increased pCO2 and HCO3

Respiratory disorders have secondary responses where?

Kidneys

Metabolic disorders have secondary response where?

Lungs

If AG > 12 then what is present?

The anion gap metabolic acidosis is present

Simply define respiratory alkalosis?

Decreased ability of lungs to excrete CO2 at a rate to keep up with production

Examples of CNS depression in respiratory acidosis?

Sedatives, CNS disease

Examples of lung diseases in respiratory acidosis?

ARDS, COPD, pulmonary edema, severe PNA

Examples of neuromuscular disorders respiratory acidosis?

Myasthenia gravis, Guillain-Barré syndrome

Treatment for CNS depression in respiratory acidosis?

Naloxone for opioid overdose

Reduce sedative exposure

Treatment for lung disease in respiratory acidosis?

Bronchodilators (albuterol) for COPD exacerbation

Loop diuretics ± IV nitroglycerin for pulmonary edema Appropriate antibiotics for severe pneumonia

Treatments for neuromuscular disorders in respiratory acidosis?

Pyridostigmine (acetylcholinesterase inhibitor) for myasthenia gravis

Simply define respiratory alkalosis?

Characterized by a decrease in pCO2 and increase in blood pH

Central stimulation of respiration in respiratory alkalosis examples?

Stroke, traumatic brain injury, salicylate/aspirin overdose, pregnancy, fever, pain, anxiety

Examples of peripheral stimulation of respiration in respiratory alkalosis?

Pulmonary embolism, asthma

Examples of hypoxia is respiratory alkalosis?

Asthma, PE, pulmonary fibrosis, high altitude

treatment for central stimulation of respiration?

Salicylate overdose: alkalinize blood/urine with sodium bicarb to enhance elimination Pain: opioids or other analgesics Anxiety: anxiolytics (e.g. benzodiazepines)

Treatment for peripheral stimulation of respiration?

Pulmonary embolism: anticoagulation ± t PA

Asthma: albuterol ± ipratropium, corticosteroids

Treatment for hypoxia?

Acute altitude sickness: acetazolamide (CAI, HCO3 wasting —> metabolic acidosis)

Anion gap metabolic acidosis (MUDPILES)

M - Methanol/ ethanol, metformin

U - Uremia

D - Diabetic ketoacidosis

P - Propylene Glycol

I - Isoniazid (INH),or Iron toxicity

L - Lactic acidosis

E - Ethylene Glycol

S - Salicylates (Aspirin)

Methanol/ ethanol overdose treatment?

NaHCO3, fomepizole (alcohol dehydrogenase inhibitor to block metabolism)

Uremia treatment?

Sodium bicarbonate, dialysis

diabetic ketoacidosis treatment?

Insulin to enhance dextrose utilization

Propylene glycol treatment?

Stop PG-containing IV medication

Iron treatment?

Deferoxamine: antidote, complexes with ferric ions to enhance renal elimination

lactic acidosis treatment?

Increase perfusion with isotonic crystalloids ± vasopressor (e.g. norepinephrine)

Ethylene glycol treatment?

Fomepizole

Salicylates treatment?

NaHCO3 to alkalinize blood/urine

Gi loss of HCO3 causes?

Severe diarrhea

Renal loss of HCO3 causes?

• Renal tubular acidosis

• Carbonic anhydrase inhibitors

• Aldosterone inhibitors

Hypercholeremia causes?

Fluid resuscitation/hyperalimentation

Treatment for GI loss of HCO3?

Antidiarrheals

Treatment for renal loss of HCO3?

• Stop carbonic anhydrase inhibitors

• Stop aldosterone inhibitors

Treatment for hypercholermia?

• Limit use of high chloride-containing IV fluids

including 0.9% NaCl

• Use balanced crystalloids or hypotonic fluids if

clinically appropriate

Treatment of saline-responsive is _________ to

Replace total body chloride deficit and limit further losses (e.g. lower diuretic dose, anti-emetics, decrease NG tube suctioning as feasible)

Administration of 0.9 NaCl

Metabolic Alkalosis (DAMPEN)

D- diuretics

A- adenoma of colon

M- Misc (bulimia)

P- posthypercapnia

E- emesis

N- nasogastric suctioning