Use of heparinized versus non-heparinized syringes for measurements of the pleural fluid pH.
BACKGROUND
Pleural fluid (PF) pH measurement is important for establishing a diagnosis and for guiding clinical management. The current standard practice is to collect PF samples for pH measurement in heparinized syringes at room temperature and to instantaneously process these samples.


OBJECTIVE
The purpose of this study is to investigate the effect of collecting PF in heparinized versus non-heparinized syringes at room temperature on PF pH measurements when processed at various time intervals.


METHODS
From 50 consecutive thoracenteses, 1 ml of PF was collected anaerobically in each of six 3-ml syringes. Only three syringes were coated with heparin. The samples were processed for PF pH measurements at time 0 (T(0)) and 1 h (T(1)) and 2 h (T(2)) after collection. All specimens were preserved at room temperature, until the measurements were carried out in duplicates by a calibrated blood gas analyzer.


RESULTS
PF pH values were significantly lower with heparinized versus non-heparinized syringes at all time intervals (T(0): pH heparinized = 7.378 +/- 0.107 vs. pH non-heparinized = 7.390 +/- 0.108; T(1): pH heparinized = 7.378 +/- 0.115 vs. pH non-heparinized = 7.389 +/- 0.111; T(2): pH heparinized = 7.367 +/- 0.105 vs. pH non-heparinized = 7.389 +/- 0.121). In the heparinized syringes, there was a significant decrease in PF pH values at T(2) versus T(0) and T(1). There were no significant changes in PF pH values over time in the non-heparinized syringes.


CONCLUSIONS
For serial PF pH measurements, the same type of syringes (either heparinized or non-heparinized) should be consistently used. With heparinized syringes, processing of PF pH measurements should be performed within 1 h after collection.
Department of Internal Medicine, American University of Beirut, Beirut, Lebanon.
Pierre K
PK
Bou-Khalil
Ghassan W
GW
Jamaleddine
Ali H
AH
Debek
Mohamad F
MF
El-Khatib
D000925:Anticoagulants / Q000008:administration & dosage*; D005122:Exudates and Transudates / Q000737:chemistry; D005260:Female; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D019152:Paracentesis / Q000295:instrumentation*; D010996:Pleural Effusion / Q000737:chemistry*; D013594:Syringes; D013696:Temperature
D000925:Anticoagulants; D006493:Heparin