ASSESSMENT OF ACID-BASE
BALANCE
RT 3025
,HYDROGEN ION CONCENTRATION
(pH)
Normal pH: 7.35 - 7.45
pH is measurement of H+ ions in the plasma.
Changes in pH of 1 unit represent a ten fold change in
[H+].
pH [H+] in nanomols/ L
7.6 26
7.5 32
7.4 40
7.3 50
7.2 63
7.1 80
7.0 100
6.9 125
, ACIDEMIA VS ALKALEMIA
pH > 7.45 = alkalemia.
pH < 7.35 = acidemia.
Allbody functions occur optimally around a pH of
7.40.
Acidosis results in depression of the CNS.
Lethargic and disoriented to comatose.
Acidosis reduces cardiac contractility.
Alkalosis results in hyperexcitability of CNS and
peripheral nerves.
muscle spasm.
, PaCO2
Normal value: 35-45 mmHg.
It is the most reliable measurement for evaluating
effectiveness of ventilation.
It is a reflection of the respiratory component of the acid-
base status.
CO2 is a waste product of metabolism; therefore, PaCO 2
identifies degree of ventilation in relation to metabolic
rate.
Fever or exercise increase metabolic rate (CO2
production) leading to hyperventilation (CO2 elimination).
BALANCE
RT 3025
,HYDROGEN ION CONCENTRATION
(pH)
Normal pH: 7.35 - 7.45
pH is measurement of H+ ions in the plasma.
Changes in pH of 1 unit represent a ten fold change in
[H+].
pH [H+] in nanomols/ L
7.6 26
7.5 32
7.4 40
7.3 50
7.2 63
7.1 80
7.0 100
6.9 125
, ACIDEMIA VS ALKALEMIA
pH > 7.45 = alkalemia.
pH < 7.35 = acidemia.
Allbody functions occur optimally around a pH of
7.40.
Acidosis results in depression of the CNS.
Lethargic and disoriented to comatose.
Acidosis reduces cardiac contractility.
Alkalosis results in hyperexcitability of CNS and
peripheral nerves.
muscle spasm.
, PaCO2
Normal value: 35-45 mmHg.
It is the most reliable measurement for evaluating
effectiveness of ventilation.
It is a reflection of the respiratory component of the acid-
base status.
CO2 is a waste product of metabolism; therefore, PaCO 2
identifies degree of ventilation in relation to metabolic
rate.
Fever or exercise increase metabolic rate (CO2
production) leading to hyperventilation (CO2 elimination).
