Question | Answer |
ABGs purpose? | evaluate overall oxygen status |
normal ABGs | pH 7.35-7.45
PaCO2 35-45
HCO3 22-26
PaO2 80-100 |
respiratory system (PaCO2) | regulates acid-base by eliminating or retaining CO2
respiratory center=medulla oblongata.responds to >CO2 |
pH response: RespSystem | responds within minutes, but less effective overtime due to fatigue |
renal system (HCO3) | conserve and reabsorb all the HCO3 it filters as well as excreting weak acids |
pH response: renalsystem | takes 2-3days to repond, but is more powerful |
at risk health conditions for acid-base imbalance | DM, COPD, KIDNEY DISEASE, ELDERLY (L333) |
why are elderly more at risk to acidbase imbalance? | they have <kidney,resp compensatory functions (L333) |
pH | measure of H+ concentrations
acid=donates H+
base=accepts H+ |
CAUSES: RespACIDOSIS | pH<7.35, PaCO2>45 HYPOVENTILATION(<RR/DEPTH)retains CO2
opiate/sedative overdose, aspiration, chest trauma, brain injury, pneumonia, pulmo edema, COPD, respiratory muscle weakness (spinal cord injury, Guillain-barre) |
S/S: RespACIDOSIS | hypoventilation, drowsiness, disorientation, headache, coma; <BP, ventricular fibrillation r/t hyperkalemia from compensation, warm, flushed skin; seizure |
CAUSES: RespACIDOSIS | pH>7.45, PaCO2<35 HYPERVENTILATION(>RR,O2)blows off CO2
septicemia, salicylate intoxication, anxiety, initial response to hypoxia (pneumonia, hf, pe) |
S/S: RespALKALOSIS | hyperventilation, lethargy, light-headed, confusion; tachycardia, dysrrhythmias r/t hypokalemia; NV, epigastric pain; tetany, numbness/tingling, hyperreflexia, seizure |
altered concentrations causing Imbalances | RespImbalances=carbonic acid concentrations
MetabolicImbalances=base bicarbonate concentrations |
CAUSES: MetabolicACIDOSIS | pH<7.35, HCO3<22
lactic acidosis, ketoacidosis r/t DM, starvation, alcoholism; renal failure, diarrhea, GI fistulas, shock |
S/S: MetabolicACIDOSIS | kussmaul respiration, drowsiness, confusion, headache, coma; <BP, dysrrhythmias r/t hyperkalemia; warm/flushed skin, NV, diarrhea, abd pain |
CAUSES: MetabolicALKALOSIS | pH>7.45, HCO3>26
vomiting/gastric suctioning, excessive antacids/steroids intake, diuretic therapy |
S/S: MetabolicALKALOSIS | dizziness, irritability, nervousness, confusion; tachycardia, dysrrhythmias r/t hypokalemia; NV, anorexia; tetany, tremors, tingling, muscle cramps,hypertonic muscles, seizure, hypoventilation (lungcompensation) |
PaO2 vs SaO2 | assessment of oxygenation
-amnt of O2 dissolved in plasma, 80-100; usually >70 adequate if person is hemodynamically stable
-% of O2 bound to hgb, >95 |
compensation | resp and renal systems compensate for each other, 20:1 ratio (bicarb:carbonic)
*partial or total/ incomplete or complete
goal: normal pH
metabolic imbalance=lungs excrete CO2
resp imbalance=kidneys alter bicarb |
interpreting ABGs | 1. pH ?acidosis or alkalosis
2. PaCO2 ?35-45
3. pH-PaCO2 relationship = resp problem?
4. HCO3 ?22-26
5. pH-HCO3 relationship = metabolic problem?
6. Look Complensation |
if compensating... | respAcidosis = >HCO3
respAlkalosis = <HCO3
metabolicAcidosis = <PaCO2
metabolicAlkalosis = >PaCO2 |