pH is a measurement of the acidity of the blood, reflecting the number of hydrogen ions present.
Lower numbers mean more acidity; higher numbers mean more alkalinity.
pH is elevated (more alkaline, higher pH) with:
Hyperventilation
Anxiety, pain
Anemia
Shock
Some degrees of pulmonary disease
Some degrees of congestive heart failure
Myocardial infarction
Hypokalemia (decreased potassium)
Gastric suctioning or vomiting
Antacid administration
Aspirin intoxication
pH is decreased (more acid, lower pH) with:
Strenuous physical exercise
Obesity
Starvation
Diarrhea
Ventilatory failure
More severe degrees of pulmonary disease
More severe degrees of congestive heart failure
Pulmonary edema
Cardiac arrest
Renal failure
Lactic acidosis
Ketoacidosis in diabetes