Respiratory Acidosis and Alkalosis
How is respiratory acidosis diagnosed?
pH <7.35 pCO2 >45mmHg
How is resp alkalosis diagnosed?
pH >7.45 and pCO2 is low - <35mmHg
What is chronic respiratory acidosis?
paCO2 elevated, pH normal/near normal Secondary to conditions such as COPD, obesity, hypoventilation syndrome, NM disorders, amyotrophic lateral sclerosis, severe restrictive ventilator defects.
What is max plasma level of HCO3 ?
45mmol/L
What is respiratory acidosis?
Build up of CO2 in the blood causing blood pH to fall. Usually due to breathing difficulty as a results of alveolar hypoventilation --> PaCO2
How is res alkalosis compensated for?
Decrease CO2 causes constriction of cerebral blood vessels and shifts O2 dissociation curve to the left. This impairs O2 delivery to the tissues Increased NM excitability due to changes in Ca2+ levels Hypokalemia as there is less hydrogen excreted so potassium is excreted in it's place to maintain charge balancep
What is the prognosis?
Depends on underlying disease --> If corrected there may be no affects but it can occur chronically if the lung condition worsens
How do you prevent resp acidosis?
Don't smoke, lose weight, be careful about taking sedatives- never mix sedatives with alcohol
What causes resp acidosis?
Hypoventilation - drugs that supress breathing benziodiazipenes, downers Disease of the airways - asthma, copd Disease of the chest - scoliosis Neuromuscular disease - drives lungs to inflate/deflate Severe obesity
What causes resp alkalosis?
Intracerebral haemorrhage, meningitis, stroke, salicyclate/progesterone drug use, anxiety, hysteria, stress, pain, cirrhosis of the liver, sepsis, elevated body temperature, hypoxia, lung disease that leads to shortness of rbeath
What is chronic resp alkalosis?
Longstanding condition which is symptomless Kidney secretes excess bicarbonate to cause metabolic acidosis to compensate If present >7 days full compensation can occur
How is resp acidosis compensated for?
Metabolically - more HCO3 is produed and retained by the kidneys to normalise CO2.HCO3 ratio --> pH
What is acute resp alkalosis?
Occurs rapidly and the person may lose consiousness and then ventialtion willr esume normal
What is respiratory Alkalosis?
Occurs when CO2 in the blood drops below normal and produces and increase in pH. Usually due to hyperventilation. Increased breathing increases alveolar respiration expelling CO2 from circulation. H+ ions and bicarbonate react to make more CO2 to maintain normal so H+ drops and pH rises
What is acute respiratory acidosis?
PaCO2>6.4kPa/ 47mmHg ph <7.35 Occurs with abrupt respiratory failure --> depression of central respiraotyr centre, disease, drugs, NM disease, airway obstruction
What are the possible complications of resp.acidosis?
Poor organ functiom, respiratory failure, shock
What are the signs and symptoms of resp alkalosis?
Primary hyperventilation, acute diziness, light headedness, agitation, confusion, cramps, tingling, numbeness around mouth and fingers, muscle twitchin, hypercapnea, chest pain, blurred vision, spasms, weakness, extreme - seizures, irregular heartbeats, tetany, chronic --> no distinctive signs usual asymptomatic
What are the sings and symptoms of resp acidosis?
Slow breathing, headaches, drowsiness, lethargy, fatigure, memory loss, restlessness, tremor, confusion, gait disturbance, blunted deep tendon reflexes, myoclonic jerks,, papilledema, rachychardia, changes in BP, swelling of blood vessels in the eyes
How do you treat resp alkalosis?
Treat underlyign condition Breathe into a paper bag Antimicrobials treat infections/pneumonia Medication to treat fever/irregular heartbeats Metabolic acidosis uses as compensation so may need to be treated to if symptomatic
How is resp acidosis treated?
Treat underlying disease - bronchodilators to reverse airway obstruction, non invasive positive pressure ventilation CPAP/BiPAP, Oxygen, stop smoking
