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Smartphones can monitor medical center pneumatic tube systems.

To the Editor:

The pneumatic tube system (PTS) has become a common means of transportation of specimens in medical centers. Although the PTS provides convenience and speed of transport, hemolysis of blood specimens and preanalytical variation have been related to excessive acceleration forces and prolonged time/ distance traveled in the PTS (1-5). As a result, regular assessment of 3-axis acceleration (i.e., forces) in PTSs has been recommended in an article in this journal (5). An editorial related to that article suggested that products designed for PTS assessment may become commercially available and capable of recording g-forces in PTSs (2). To date, however, we have found no products that are available in the US designed to record forces in the PTS used in our health system (Swisslog).

Many modern smartphones are equipped with an accelerometer that measures acceleration forces. The devices also contain a chronometer, and they are nearly ubiquitous and are portable, and small enough to fit in a PTS carrier, suggesting that they might be useful for monitoring forces and time associated with travel of samples through a PTS.

To explore this possibility, we used a relatively old cell phone (iPhone 5) and a readily available data logger app (Sensor Kinetics Pro). The smartphone was wrapped in bubble wrap, placed in a carrier, and sent through the hospital PTS. The data logger app collected data on 3-axis acceleration vs time in transit. As shown in Fig. 1, the smartphone experienced shocks with peak acceleration forces exceeding 8g (78 m/s2). These forces are similar to the forces of up to 10g reported by Streichert et al. in their PTS when it was at a high-speed setting (5). Streichert et al. documented that such forces are associated with sample hemolysis. The smartphones that we sent through the PTS were not damaged during transport, and the results were reproducible when the smartphone was sent through the PTS repeatedly (not shown).

The iPhones, like most smartphones, also have audiovisual recording capabilities and a light source. We used these capabilities to visualize the effect of acceleration forces on blood samples during transit through the PTS. One smartphone was used to make an audiovisual recording of blood in a filled heparinized sample tube, and a second smartphone illuminated the tube in the carrier. As can be seen in the resulting smartphone video (see the online Supplemental Video link that accompanies the online version of this article at http:// www.clinchem.org/content/vol62/ issue6), the sample experienced marked turbulence, resulting in a foamy or frothy appearance of the blood sample, with large and small air pockets. The foamy appearance of the sample was readily appreciated upon direct visual inspection immediately after transport of the sample, but dissipated within a few minutes.

These findings suggest that smartphones can be used to quickly and economically monitor the PTS variables of force and time that have been shown to affect the integrity of patient specimens. Although we used an iPhone 5, other types of smartphones have similar capabilities and presumably could be used; this possibility will require documentation. Due to the convenience and efficiency of this approach, it has several possible applications in medical centers that use PTSs: (a) a medical center may use this approach to establish PTS acceptability criteria or recommend thresholds not to be exceeded to ensure sample integrity during transport; (b) this approach can be used to investigate a presumptive problematic PTS route; (c) because PTS routes are often installed, and may be modified during medical center renovations, this approach can be used to quickly assess or reassess route performance and consistency; and (d) this approach may be especially useful for more-frequent monitoring of PTS routes that service specific patient populations (such as oncology or hematology patients) whose blood samples may be more susceptible to cellular damage during transport.

Smartphones appear to provide the capabilities needed to monitor medical center PTSs, with the benefits of being cost effective, convenient, and widely available.

References

(1.) Evliyaoglu O, Toprak G, Tekin A, Basarali MK, Kilinc C, Colpan L. Effect of pneumatic tube delivery system rate and distance on hemolysis of blood specimens. J Clin Lab Anal 2012; 26:66-9.

(2.) Felder RA. Preanalytical errors introduced by sample-transportation systems: a means to assess them. Clin Chem 2011; 57:1349-50.

(3.) Kavsak PA, Mansour M, Wang L, Campeau S, Clark L, Brooks D, Trus M. Assessing pneumatic tube systems with patient-specific populations and laboratory derived criteria. Clin Chem 2012; 58:792-5.

(4.) Steige H, Jones JD. Evaluation of pneumatic-tube system for delivery of blood specimens. Clin Chem 1971; 17:1160-4.

(5.) Streichert T, Otto B, Schnabel C, Nordholt G, Haddad M, Maric M, et al. Determination of hemolysis thresholds by the use of data loggers in pneumatic tube systems. Clin Chem 2011; 57:1390-7.

Garrett R. Mullins [1] *

James H. Harrison [1, 2]

David E. Bruns [1]

[1] Division of Laboratory Medicine Department of Pathology

[2] Department of Public Health Science University of Virginia School of Medicine and Health Sciences Center Charlottesville, VA

* Address correspondence to this author at: Department of Pathology PO Box 800168 University of Virginia School of Medicine Charlottesville, VA 22908 E-mail grm9yd@virginia.edu

Previously published online at DOI: 10.1373/clinchem.2016.257063

Author Contributions: All authors confirmed they have contributed to the intellectual content of this paper and have met the following 3 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; and (c) final approval of the published article.

Authors' Disclosures or Potential Conflicts of Interest: Upon manuscript submission, all authors completed the author disclosure form. Disclosures and/or potential conflicts of interest:

Employment or Leadership: None declared. Consultant or Advisory Role: None declared. Stock Ownership: J. H. Harrison, Apple, Inc. Honoraria: None declared.

Research Funding: None declared.

Expert Testimony: None declared.

Patents: None declared.

Caption: Fig. 1. Three-axis acceleration vs time plot of data collected by a smartphone (iPhone 5) using a data logger app (Sensor Kinetics Pro) while traveling through a pneumatic tube system from a patient-care area to the clinical laboratory.
Table 1. Summary of OGTT classified as positive according to the 2013
CDA (2) and ADA guidelines criteria (3).

                                      CDA criteria   ADA criteria

Number of pregnancy OGTTs                  10 773         10 773
Total number positive                        2776           4033
Total diagnosed by 2-h result only            850            994
% of positives diagnosed                       31             25
  by 2-h result only
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Article Details
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Title Annotation:Letters to the Editor
Author:Mullins, Garrett R.; Harrison, James H.; Bruns, David E.
Publication:Clinical Chemistry
Article Type:Letter to the editor
Date:Jun 1, 2016
Words:1076
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