Respiratory alkalosis / acidosis

Respiratory acidosis

Causes:

· characterised by increases in PCO2 (>45 mm Hg) leading to increased carbonic acid 2^o:

i) impairment in CO₂ clearance

a) impaired diffusion of CO2 via respiratory membrane

eg COAD

b) inadequacies of expiratory processes

eg blocked airway, crushed chest

c) depressed respiratory rate or depth

eg narcotic drugs, pain

ii) increased CO₂ production

a) excessive increased metabolic rate

eg fever, hyperthyroidism

Signs & Symptoms

· depression of CNS: irritability & drowsiness

· elevation of respiratory rate & depth (Kussmaul respirations)

· tachycardia & arrhythmia

· Hypercalcemia & hyperkalemia

Causes:

· characterised by depression in HCO₃^- caused by:

i) increased clinical loss of bicarbonate

a) increased small bowel output

eg prolonged diarrhoea, lower GIT drainage

ii) conversion of buffer bicarbonate to carbonic acid as excess nonvolatile acids are neutralized

a) elevations in nonvolatile acids 2^o increased intake/production

eg ingestion salicylic acid

eg lactic acid 2^o anaerobic metabolism

eg ketone bodies 2^o insulin deficit

b) elevations in nonvolatile acids 2^o decreased output

eg renal failure

Signs & Symptoms

· depression of CNS: irritability & drowsiness

· elevation of respiratory rate & depth (Kussmaul respirations)

· tachycardia & arrhythmia

· Hypercalcemia & hyperkalemia