how is pH measured
increased H+ = decreased pH (acidic)
decreased H+ = increased pH (alkalotic)
what are the aspects measured in an ABG
- pH
- PCO2
- PO2
- HCO3
what is buffering pairs
- bicarbonate/ carbonic acid system
- disodium/ monosodium phosphate buffer system
- haemoglobin/ oxyhaemoglobin system
- protein buffer system
what is bicarbonate/ carbonic acid buffer
- disease process results in less bicarb = more H+ = pH decreases
- to overcome this and maintain normal pH there will be less carbonic acid produced = less H+ = pH returns to normal
what is respiratory system in acid base balance
- the lungs are important
- it will compensate for disturbance of metabolic origin
- works within minutes to hours
what is renal system in acid base balance
- kidneys are the long term regulators of blood pH
- it will compensate for disturbance of respiratory origin
- works from hours to days
- the kidneys will retain or eliminate both HCO3 and H+ ions as needed
what are the lungs and kidneys roles?
- attempt to balance each other to maintain acid base balance in blood
- if pH changes because of a repsiratory disorder the renal system will be responsible for making corrections to balance blood
what is acidosis
- too much H+
- pH <7.35
what is alkalosis
- not enough H+
- pH >7.45
what is being measured in ABG
- pH - measures of H+ in blood
- PCO2 - amount of dissolved CO2 in blood
- HCO3 - amount of HCO3 in blood
- PO2- amount of dissolved O2 in blood
- BE - amount of excess or insufficient HCO3 in the system, negative BE = deficit of HCO3 in blood = excess acid
- SaO2 - % of hB saturated with oxygen
normal values of ABG
pH
* range 7.35-7.45
* acidosis - <7.35
* alkalosis - >7.45
PaCO2
* range - 35-45mmHg
* acidosis - >45
* alkalosis - <35
HCO3
* range - 22-28 mEq/L
* acidosis - <22
* alkalosis - >26
PaO2
* range - 80-100 mmHg
* hypoxaemia - <80
SpO2
* range - 95 - 100%
* hypoxaemia - <95
causes and risk factors of pneumonia
causes
* aspiration of orophaeyngeal secretions composed of bacterial flora or gastric content
* inhalation of contaminants
* contamination from systemic circulation
risk factors
* advanced age
* compromised immunity
* underlying lung disease particularly COPD
* alcoholism
* smoking
* malnutrition
* chest trauma
* impaired swallowing
what is the most common cause of chronic obstructive pulmonary disease
tabacco smoking
respiratory rate and depth are controlled by what?
apneustic and pneumotaxic centres in the pons
why is monitoring respiratory status a nursing priority when a client with COPD is recieving oxygen
decreased arterial oxygen is the stimulus for breathing in a client with COPD
