Respiratory Acidosis and Alkalosis Flashcards
Normal Arterial blood gas
HCO3- = 24 PaCO2= 40 PaO2= 95
Alveolar gas normal
PaCO2= 36 PaO2= 105
Venous blood gas normal
PvCO2= 50 PvO2= 30-40
Respiratory acidosis
Build up of CO2 in blood
pH more acidic
Brough about by some form of breathing difficulty
Resp acidosis MOA
CO2 accumulates if lungs don’t dispel it through alveolar ventilation
Alveolar hypoventilation
Increased PCO2- hypercapnia
–> decrease in blood pH
Resp acidosis main causes
Hypoventilation due to drugs that suppress breathing
Diseases of airway
Diseases of chest (scoliosis)
Diseases that affect nerves + muscles that drive lungs to inflate or deflate
Severe obesity
Degree of change in blood pH depends on
Body’s ability to buffer the excess CO2
Henderson-Hasselbach equation
pH= 6.1 + log [(HCO3-)/0.03 x pCO2]
pH
log(1/[H+])
pKa
6.1 at body temp
Resp acidosis chemicals
High PaCO2 (>40mmHg) Slightly raised HCO3- (>24mmHg) Ratio of [HCO3-]/pCO2 decreases -->pH also decreases
Resp Acidosis symptoms explanation
CO2 lipid soluble gas- diffuse across BBB
HCO3- = ion, can’t enter CSF
–> CSF less buffered than blood so pH changes faster in response to CO2
Resp acidosis symptoms
Headache Drowsiness Lethargy Anxiety Sleepiness
Resp acidosis Signs
Slow breathing Gait disturbance Blunted deep tendon reflexes Disorientation Tremor Myoclenic jerks Papilloedema Tachycardia BP drop
Resp Acidosis Diagnosis
pH<7.35
pCO2 >45mmHg
Blood sample for pH
ABG
Resp Acidosis Treatment
Aimed at underlying lung disease
–> bronchodilators, ventilation, O2, smoking cessation
Acute Resp acidosis findings
pCO2 > 6.3kPa/47mmHg
pH<7.35