Sleep Apnea/Acid-Base

characteristics of sleep apnea

collapse of pharyngeal airway that results in sleep obstructive states with hypoxia and hypercarbic events

cardiovascular effect of sleep apnea

hypertensive events, tachycardia, arrhythmogenesis

physiologic affects of sleep apnea

hypopnea, apnea, SNS activation, increase in pulmonary pressure, oxidative stress

cause of obstructive sleep apnea

tongue falls to the back of the throat and blocks the airway

STOP-bang screening tool for sleep apnea

snore, tired, observation, (blood) pressure, BMI, age, neck circumference, gender

parts of obstructive sleep apnea diagnosis

daytime and nighttime symptoms, interview of sleep partner, STOP-bang

gold standard diagnostic test for obstructive sleep apnea

polysomnogram

best therapy treatment for obstructive sleep apnea

CPAP machine

arterial blood gas testing (ABG)

partial pressures of gases and acid-base content from blood drawn from an artery

components of an arterial blood gas testing

pH, pO2, pCO2, HCO3, saO2, base/excess deficit

normal blood pH

7.35-7.45

normal pO2

80-100 mmHg

normal pCO2

35-45 mmHg

normal HCO3

22-26

low pH

acidic

high pH

alkaline

control of pCO2

controlled by lungs, change occurs rapidly

control of HCO3

controlled by kidneys, change occurs slowly

effect of hypoventilation

increase/retain CO2 → decrease pH → acidosis

effect of hyperventilation

decrease/eliminate CO2 → increase pH

effect of retention of HCO3

increase HCO3 → increase pH

effect of elimination of HCO3

decrease HCO3 → decrease pH → acidosis

common acid-base imbalance states

metabolic and respiratory acidosis

characteristics of respiratory acidosis

pH below 7.35, hypercapnia, lungs cannot expel CO2

characteristics of respiratory alkalosis

pH above 7.45, hypocapnia, CO2 blown off faster than it is produced, hyperventilation

consequences of respiratory acidosis (high CO2)

CNS depression, congestive heart failure, lung disease, chest wall disorders, airway obstruction, neuromuscular diseases

characteristics of metabolic acidosis

pH below 7.35, increase in hydrogen ions (decrease in excretion), decreased HCO3 production

consequences of metabolic acidosis

lactic acidosis (excess acid), sepsis, diabetic ketoacidosis, renal failure

function of arterial blood gas interpretation

determine whether the pathology is due to a pulmonary or metabolic issue

steps of arterial blood gas interpretation

1. acidosis vs. alkalosis

2. respiratory vs. metabolic

3. is there any compensatory input