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Medicare private fee-for-service.

Pfiesteria piscicida

(fēs-tĕr’ē-ă pĭs-ĭ-sīd′ ā) A unicellular marine organism, which may or may not produce a toxin, depending on environmental conditions. When toxic, it has been implicated in the death of millions of fish in the estuaries of North Carolina, Delaware, and Maryland. The toxin can become aerosolized, and if humans are exposed to it, severe neurological, mental, and physical illness may occur. Specific therapy to combat the toxin is not available, but concomitant infections can be treated with tetracyclines.


phosphofructokinase deficiency.


pay for performance.

P:F ratio

The ratio of arterial partial pressure of oxygen to inspired fractional concentration of oxygen; used to measure oxygen transfer.


Progression-free survival.


platelet function test; pulmonary function test.






pteroylglutamic acid.


1. Pharmacopoeia. 2. Symbol for phenyl.


[Ger. Potenz, power + H, symbol for hydrogen] In chemistry, a measure of the hydrogen ion concentration of a solution. The degree of acidity or alkalinity of a substance is expressed in a pH value. A solution that is neither acid nor alkaline has a pH of 7. Increasing acidity is expressed as a number less than 7, and increasing alkalinity as a number greater than 7. Maximum acidity is pH 0 and maximum alkalinity is pH 14. Because the pH scale is logarithmic, there is a 10-fold difference between each unit. For example, pH 5 is 10 times as acid as pH 6 and pH 4 is 100 times as acid as pH 6. The general mathematical formula defining pH is: pH = –log [H +], in which pH is the negative logarithm of the hydrogen ion concentration. The pH of a solution may be determined electrically by a pH meter or colorimetrically by the use of indicators. A list of indicators and the pH range registered by each is given under the indicator.

PATIENT CARE: A pH less than 6.8 or greater than 7.8 is incompatible with human life. SEE: illus.; table; indicator.




Values of body fluids and some familiar solutions


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pH of Some Fluids
Material pH
10% HCl 1.0
Gastric juice 1.0–5.0
0.1% HCl 3.0
Pure water (neutral) at 7.0
Blood plasma 7.35–7.45

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