This is not a well studied topic, however these articles do cover most questions surrounding the matter.

1: Subbarayan D, Choccalingam C, Lakshmi CKA. The Effects of Sample Transport by Pneumatic Tube System on Routine Hematology and Coagulation Tests. Adv Hematol. 2018 Jul 2;2018:6940152. doi: 10.1155/2018/6940152. eCollection 2018. PubMed PMID: 30079089; PubMed Central PMCID: PMC6051325. Full text

2: Petit M, Mine L, Pascreau T, Brouzes C, Majoux S, Borgel D, Beaudeux JL, Lasne D, Hennequin C. Preanalytical influence of pneumatic tube delivery system on results of routine biochemistry and haematology analysis. Ann Biol Clin (Paris). 2017 Dec 1;75(6):703-712. doi: 10.1684/abc.2017.1287. PubMed PMID: 29043982.

3: Le Quellec S, Paris M, Nougier C, Sobas F, Rugeri L, Girard S, Bordet JC, Négrier C, Dargaud Y. Pre-analytical effects of pneumatic tube system transport on routine haematology and coagulation tests, global coagulation assays and platelet function assays. Thromb Res. 2017 May;153:7-13. doi: 10.1016/j.thromres.2016.12.022. Epub 2016 Dec 28. PubMed PMID: 28292729. Full text

4: Amann G, Zehntner C, Marti F, Colucci G. Effect of acceleration forces during transport through a pneumatic tube system on ROTEM® analysis. Clin Chem Lab Med. 2012 Mar 9;50(8):1335-42. doi: 10.1515/cclm-2011-0800. PubMed PMID: 22868797.

5: Kratz A, Salem RO, Van Cott EM. Effects of a pneumatic tube system on routine and novel hematology and coagulation parameters in healthy volunteers. Arch Pathol Lab Med. 2007 Feb;131(2):293-6. PubMed PMID: 17284116. Full text

6: Calmette L, Ibrahim F, Gouin I, Horellou MH, Mazoyer É, Fontenay M, Flaujac C. Impact of a pneumatic tube system transport on hemostasis parameters measurement: the experiment of Cochin universitary hospital (AP-HP, Paris, France). Ann Biol Clin (Paris). 2017 Feb 1;75(1):93-100. doi: 10.1684/abc.2016.1215. Review. PubMed PMID: 28132949.

7: Suchsland J, Winter T, Greiser A, Streichert T, Otto B, Mayerle J, Runge S, Kallner A, Nauck M, Petersmann A. Extending laboratory automation to the wards: effect of an innovative pneumatic tube system on diagnostic samples and transport time. Clin Chem Lab Med. 2017 Feb 1;55(2):225-230. doi: 10.1515/cclm-2016-0380 PubMed PMID: 27362964.

8: Dhar S, Basu S, Chakraborty S, Sinha S. Evaluation of the pneumatic tube system for transportation of packed red cell units. Asian J Transfus Sci. 2015 Jul-Dec;9(2):195-8. doi: 10.4103/0973-6247.154254. PubMed PMID: 26420944; PubMed Central PMCID: PMC4562145. Full text

9: Tiwari AK, Pandey P, Dixit S, Raina V. Speed of sample transportation by a pneumatic tube system can influence the degree of hemolysis. Clin Chem Lab Med. 2011 Nov 10;50(3):471-4. doi: 10.1515/CCLM.2011.779. PubMed PMID: 22070350.

10: Fernandes CM, Worster A, Eva K, Hill S, McCallum C. Pneumatic tube delivery system for blood samples reduces turnaround times without affecting sample quality. J Emerg Nurs. 2006 Apr;32(2):139-43. PubMed PMID: 16580476. Full text