Changes in blood gas samples produced by a pneumatic tube system

Abstract

Aims: To investigate the effect of a pneumatic tube system (PTS) on the results of samples sent for blood gas analysis to a central laboratory.Methods: Blood gas samples were analysed immediately or sent via the PTS to the laboratory for analysis. In addition, samples sent via the PTS in a pressure sealed container were compared with those sent non-pressure sealed to the laboratory. Results: Samples sent via the PTS had significant alterations in their pO 2 values, which were not seen when samples were carried by hand to the laboratory. There was no effect on pCO 2 and pH values. The use of a pressure sealed container abolished the alteration in pO 2 values seen. Conclusions:Samples for blood gas analysis should be transported via a PTS using a pressure sealed container to avoid artefacts in the pO 2 . R apid sample delivery systems, usually pneumatic tube systems (PTS), have been installed in hospitals to reduce delays in delivering samples from the patient to the core laboratory. The use of such rapid sample delivery systems, combined with electronic data links, would be expected to improve laboratory turnaround times (TATs). This would enable the laboratory to provide an analytical service with TATs comparable to that of a satellite "emergency" laboratory or point of care testing (POCT) facility at less cost.1 Studies have shown that there are no significant effects on analytes, particularly pO 2 , pCO 2 , and pH.2 However, a recent report has shown that there is perturbation of pO 2 values when there is air contamination. 3 We have examined the impact of an air tube delivery system (ASCOM GCT GmbH, Keven, Germany) on blood gas samples analysed immediately or sent via the pneumatic tube system to the laboratory for analysis."The use of rapid sample delivery systems, combined with electronic data links, would be expected to improve laboratory turnaround times" METHODSArterial blood samples were drawn from patients in the intensive care unit (ICU) of a UK district general hospital. The ICU is located in a separate building from the pathology laboratory, but on the same geographical site. All of the hospital wards including the ICU are connected to the central pathology laboratory via a pneumatic air tube delivery system. The ICU is 520 metres from the laboratory, with a median delay from sampling to arrival at the laboratory of 19 minutes (interquartile range, 13 to 23). Ethical permission for our study was obtained from the local research ethics committee. Samples were taken into commercially supplied preheparinised syringes (Mieno Corp, Tokyo, Japan). Visible air bubbles were expelled and the samples capped and processed immediately.A three stage study was performed, as follows:Phase 1. Consecutive samples were drawn in duplicate from patients over a two week period. One sample was analysed immediately on the ICU by a member of the ICU staff. The second sample was capped and sealed in a gas tight plastic envelope and taken immediately, by hand, to the laboratory for analysis by a member of the laboratory staf...

Determination of Hemolysis Thresholds by the Use of Data Loggers in Pneumatic Tube Systems

“…However, blood samples are particularly sensitive to strong forces or vibrations with high frequencies and require special attention. It has been shown that PTS transport could affect samples (7-9 ) and lead to hemolysis or altered blood gases (5 ). On the other hand, there are hospitals working with PTSs constructed in such a way that they do not affect samples or do so only minimally (1, 10 -12 ).…”

“…The parameters were chosen with respect to literature on the evaluation of similar systems (4,5 ). We decided to analyze an expanded panel including differential blood count (LH 750, Beckman Coulter), coagulation tests (BCS XP, Siemens), erythrocyte sedimentation rate (S2000, Sarstedt), sodium, potassium, chloride, phosphate, glucose, magnesium, aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), lipase, LDH, troponin T, IgG, free thyroxine (Modular-System, Roche), procalcitonin (Kryptor, Brahms), and blood gas analysis (ABL 700, Radiometer).…”

The impact of pneumatic tube system on routine laboratory parameters: a systematic review and meta-analysis

“…In vitro hemolysis, caused by PTS, has been reported to alter the blood specimen's quality and potentially affects clinical laboratory measurements such as biochemical, most notably potassium (K), lactate dehydrogenase (LDH) [4], hematology and coagulation parameters. Moreover, these strong forces can potentially affect blood gas measurements [5] and spectrophotometric analysis of cerebrospinal fluid [6]. Most recently, the transportation of blood samples through the PTS has been shown to affect in vitro platelet function [7].…”

The Clinical Significance of Patient Specimen Transport Modality: Pneumatic Tube System Impact on Blood Gas Analytes

“…PTS induced pressure changes must be considered as a possible source for pre-analytical error for blood gas measurements. 4,5 Past investigations have observed that blood gases were not significantly altered when transported by PTS. [6][7][8] However, when an air bubble is present within a specimen transported via PTS, the P O 2 is significantly affected.…”