Implementation of a Pneumatic-tube System for Transport of Blood Specimens WOJCIECH POZNANSKI, M.D., FRANCES SMITH, M.D., PH.D., AND FRANK BODLEY, PH.D.
HOSPITAL PNEUMATIC-TUBE SYSTEMS have been widely used for efficient transport of mail, drugs, and medical reports. In the first attempts to adapt these systems for blood transport, damage to the erythrocyte and other blood cells was encountered. Attempts to solve this problem have been made. 3 - 5,68 - 9 These efforts were applied to experimental models, and the closest to a functional system was the pilot project at the Erie County Laboratories. 8 A pneumatic-tube system incorporating structural modifications designed to reduce trauma to blood specimens was installed in our hospital. This paper describes these modifications and our experience with blood transport by this system. Materials and Methods Description of the System The pneumatic system for conveying blood samples at the Ottawa Civic Hospital was manufactured by the Mosler Airmatic Company. It is a unidirectional, continuously operating pneumatic-tube system dediReceived April II, 1977; received revised manuscript June 10, 1977; accepted for publication June 10, 1977. Address reprint requests to Dr. Smith: Division of Biochemistry, Department of Laboratory Medicine, Ottawa Civic Hospital, 1053 Carling Ave., Ottawa, Ontario K1Y 4E9, Canada.
Division of Biochemistry, Department of Laboratory Medicine Ottawa Civic Hospital, and the Departments of Biochemistry and Medicine of the University of Ottawa, Ottawa, Ontario, Canada
cated to specimen transport linking the emergency department and the intensive care unit with the biochemistry laboratory. The physical pathway of the tube travels 485 m through several connecting hospital buildings and rises and falls a total of four levels (Figs. 1 and 2). There is a buried underground section, as well as externally exposed portions that are coated and enclosed in mull wrap and moisture-proof insulation. This is important, as the carriers will jam if moisture condenses within the tube. In the future, the present system will be extended to the main operating areas and a newly constructed cardiac unit, creating a total circuit of about 833.3 m (see Fig. 1). The intracardiac portion of the extension was installed at the time the unit was built. Carriers are returned from the lab to their point of origin by our conventional pneumatictube system, also designed by Mosler Airmatic. The system was engineered to maintain the carriers at a constant speed (3.6 m/sec), regardless of load. This is significantly less than the usual velocity of pneumatic systems. The carriers are routed smoothly and automatically through gentle bends without the use of deflector arms. Deceleration of the carriers is controlled by an air brake. The landing site at the receiving station is well padded. As a safety feature, the system was designed to prevent access to the system when a carrier is in transit. Further, it is equipped with an alarm system, which is activated when a carrier becomes jammed. The carriers are constructed of plexiglas material with a leather hinge top-flap and at the opposite end a station selection control (Fig. 3D). This is electronically preset to return to the original sending station when the carrier is placed in the conventional system. No setting is necessary when the carrier is sent to the laboratory, as this is the only possible destination in our system. The carriers are color-coded so as not to be confused with carriers from the conventional system. The inserts are zipper-closed and padded with foam rubber, which holds the specimens snugly in
0002-9173/78/0800/0291 $00.75 © American Society of Clinical Pathologists
291
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
Poznanski, Wojciech, Smith, Frances, and Bodley, Frank: Implementation of a pneumatic-tube system for transport of blood specimens. Am J Clin Pathol 70: 291-295, 1978. Whole-blood specimens were transported through an installed 485-meter pneumatic-tube system dedicated to blood transport. The system featured constant-speed, low-carrier-velocity travel (3.6 m/sec) with controlled deceleration prior to arrival at its destination. Inserts were designed with ample use of padding to minimize agitation during transport and landing. Serum potassium, hemoglobin, and lactate dehydrogenase activity and whole-blood pH, PCo2> and P,,, were not altered in freshly drawn blood transported in this system. Partial filling or heparinization of the specimen containers did not alter the results. When specimens were allowed to clot prior to pneumatic-tube transport, significantly higher levels of serum lactate dehydrogenase were obtained. This study demonstrates that transport of whole-blood specimens by pneumatic tube without damage to blood components is feasible. (Key words: Blood specimen transport; Pneumatic tube; Nature of specimen.)
POZNANSKl, SMITH AND BODLEY
292
1
A.J.C.P. • August 1978
rf-STATON'S CARDIAC \ CARE
8SKtt»
STATIONS OPERATNG ROOM
FIG. 1. Plot diagram of hospital complex and pneumatic-tube system. Actual dedicated system: solid line; proposed system: broken line; conventional system stations: diamonds. Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
SWnON'3 EMERGENCY
STATIONS
H=FT
ELEVATION VEW
\t
STATION" 4
*!-
£
V r r r a l
\
J.
Onxnl Floor
STATION'S
STATION 1
FIG. 2. Model diagram of hospital complex and pathway of pneumatic-tube system.
Scale f-4G0'
LABORATORY SUGGESTIONS
Vol. 70 . No. 2
293
place (Fig. 3A). The outside diameter of the insert is cut so that there is no space for movement within the carrier. Normally the specimens are placed crosswise in the insert, no more than five per carrier. Blood Constituent
Measurement
The blood serum lactate dehydrogenase activity (LDH), sodium (Na + ), potassium (K + ), chloride (Cl~), carbon dioxide (C0 2 ), glucose, hemoglobin, and urea nitrogen, and whole-blood pYL and gases (P 02 , Pco2) were measured, because either they are frequently requested as emergency tests or they can provide evidence of cellular destruction, or both. Standard clinical laboratory procedures (Technicon SMA 6 and 12, Corning pH/Blood Gas 165) were employed for these determinations. Hemoglobin was measured according to the method of Harboe. 4 Standard statistical methods were employed. 1
Working Procedure Duplicate blood samples were drawn by venipuncture into 10-ml Vacutainer tubes* from patients in emergency or intensive care. The specimens were collected in plain, red-stoppered Vacutainers with the tubes filled to capacity unless otherwise specified. One tube was sent through the pneumatic system while the other was transported by porter to the laboratory. Upon receipt, the duplicate samples were processed together without special treatment. Clotting was allowed to come to completion, when necessary; Sure-Sep®t was applied to the clotted blood prior to centrifugation. Blood specimens for pH and gas determinations were collected in heparinized glass syringes, stoppered with syringe caps, wrapped in a * Becton-Dickinson. t General Diagnostics.
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
FIG. 3. Carrier and its insert. A, specimens being loaded into carrier insert. B, syringe wrapped in cold gel pack. C, syringe being loaded into carrier insert. D, insert being placed inside carrier.
POZNANSKl, SMITH AND BODLEY
294
Table I. Reproducibility of Methods C.V. Test
Mean*
± SD
(%)
Glucose (mmol/l) Urea nitrogen (mmol/l) Na + (mmol/l) K+ (mmol/l) CO, (mmol/l) CI (mmol/l) Lactate dehydrogenase (ug/1) Hemoglobin (g/l)t P,-„, (mm Hg) PH P,„ (mm Hg)
5.775 7.50 127.4 3.78 12.7 109.5 235.4 0.141 36.3 7.411 102.0
0.165 0.18 1.2 0.06 0.8 1.1 8.9 0.011 1.9 0.009 5.9
2.9 2.4 1.0 1.6 6.3 1.0 3.8 7.8 5.3 0.1 5.8
* n = 30. t n = 20.
Test
Porter (Mean*)
Tube (Mean*)
d
SE Diff.
Glucose (mmol/l) Urea nitrogen (mmo 1/D Na + (mmol/l) K + (mmol/l) C 0 2 (mmol/l) CI" (mmol/l) Lactate dehydrogen;ase (u/l) Hemoglobin (g/l)
7.246 9.19 137.9 4.19 27.9 99.3 303.0 0.077
7.324 9.23 137.8 4.18 28.5 100.8 307.2 0.103
0.078 0.04 0.1 0.01 0.6t 1.5t 4.2 0.026
0.125 0.05 0.3 0.02 0.2 0.6 5.0 0.019
seen to conform to acceptable laboratory standards.2 Except for hemoglobin, quality control sera were analyzed and the between-assay precision calculated. For hemoglobin the within-run precision was determined using a patient sample. In Table 2 the effects of pneumatic-tube blood transport on various serum constituents are shown. Other than slightly higher values for total C0 2 and Cl~ obtained for specimens transported through the system, no effect was detected. The effect of variation in the nature of the specimen collected was investigated. As shown in Table 3, the presence of partly filled tubes or heparinized blood did not alter the serum chemistry results. Transport of fully clotted blood through the system was associated with a definite elevation in serum LDH. Blood-gas and pH measurements were performed on whole-blood specimens collected and transported in heparinized glass syringes. No difficulty in transport arose. The test results were not affected by transport of the blood through the pneumatic tube (Table 4). The existing portion of the blood transport tube within the cardiac unit was evaluated. This segment is only 67 m long and at present is designed to transport specimens at 5.6 m/sec. As shown in Table 5, the greater transport speed over this shorter distance did not affect the test results.
* n = 35. t Difference statistically signiificant. P = 0.05.
Discussion
cold gel pack placed singly in the inserts, and sent immediately (Figs. 7>B, 3C). Results The reproducibility of our analytic methods during the study period is presented in Table 1, and may be
Our results indicate that routine transport of blood specimens by pneumatic tube is feasible. The small differences in total C0 2 and Cl~ associated with pneumatic-tube transport do not appear clinically important. The elevation of LDH associated with the transport of clotted blood through the pneumatic system is of
Table 3. Effect of Nature of Specimen on Test Result Test*
Specimen
Control (Mean)
Tube (Mean)
d
t§
Plain Vacutainer sent immediatelyt (n = 22)
K+ Hemoglobin Lactate dehydrogenase
3.98 0.086 167.5
4.02 0.081 172.0
0.04 0.005 4.5
0.784 0.475 1.692
Half-filled plain Vacutainer sent immediatelyt (n = 8)
K+ Hemoglobin Lactate dehydrogenase
4.09 0.243 198.0
4.00 0.144 192.2
0.09 0.099 5.8
1.645 0.961 0.528
Filled plain Vacutainer sent after 15 minutest (n = 23)
K+ Hemoglobin Lactate dehydrogenase
3.85 0.108 233.1
3.84 0.110 264.3
0.01 0.002 31.2
0.333 0.192 2.966'
Filled heparinized Vacutainer sent immediatelyt (n = 24)
K+ Hemoglobin Lactate dehydrogenase
3.83 0.051 189.0
3.80 0.036 195.5
0.03 0.015 6.5
0.515 1.235 0.699
* Units are K \ mmol/l; hemoglobin, g/l; lactate dehydrogenase, ug/1. t Control is completely filled plain Vacutainer sent by porter. t Control is completely filled heparinized Vacutainer sent by porter.
§ Student's t test for paired data.
V < o.oi.
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
Table 2. Effects of Blood Transport Through the Pneumatic-tube System
A.J.C.P. • August 1978
LABORATORYSUGGESTIONS
vol. 70 . No. 2
295
Table 5. Effect of Transport Through Cardiac Unit Tube
Table 4. Effects of Pneumatic-tube Transport on pH and Blood-gas Results Test
Porter (Mean*)
Tube (Mean*)
a
SE Diff.
Test
Porter (Mean*)
Tube (Mean*)
d
SE Diff.
Pro, (mm Hg) P„, (mm Hg)
7.420 39.8 96.2
7.421 39.2 94.8
0.001 0.6 1.4
0.003 0.9 3.6
Glucose (mmol/1) Urea nitrogen (mmol/1) Na+ (mmol/1) K+(mmol/1) C0 2 (mmol/1) CI" (mmol/1) Lactate dehydrogenase (/i.g/1)
6.567 6.10 138.4 4.46 27.7 99.2 255.4
6.496 6.10 138.7 4.44 27.6 99.2 258.0
0.071 0 0.3 0.02 0.1 0 2.6
0.934 0 0.2 0.03 0.1 0 3.6
* n •- 43.
* n = 56.
carriers. The safety lockout may prove undesirable as utilization of the system increases, but this feature can be modified. As technology in this field advances, the development of pneumatic systems capable of transporting both blood specimens and other materials within hospitals seems probable. Acknowledgments. The Administrators and the Department of Planning and Development of the Ottawa Civic Hospital assisted in this project.
References 1. Bradford Hill A: Principles of Medical Statistics. Ninth edition. New York, Oxford University Press, 1971. p 390 2. Crosswell MA: How useful is the clinical chemistry laboratory. Lab-Lore 6:353-356, 1975 3. Delbruck A, Porchman H: Uber den einfluss des rohrposttransportes auf klinischen untersuchungsmaterial unter verschiedenen betriebsbedingungen. Klin Chem Klin Biochem 6:211-216, 1968 4. Harboe M: A method for determination of hemoglobin in plasma by near-ultraviolet spectrophotometry. Scand J Clin Lab Invest 11:66-70. 1959 5. Lapidus BM, Dehner GF: Gravity delivery of laboratory specimens. Am J Clin Pathol 64:127-135, 1975 6. McClellan EK, Nakamura RM, Haas W, et al: Effect of pneumatic tube transport system on the validity of determinations in blood chemistry. Am J Clin Pathol 42:152-155, 1964 7. Peckauskas RA. Portnoy AL, Narayanan S: Investigations into the biochemical changes in the red cell membrane following irradiation of plasma. Abstracts IX Intern. Cong. Clin. Chem. 81. 1975 8. Pragay DA, Edwards L, Toppin M. et al: Evaluation of an improved pneumatic tube system suitable for transportation of blood specimens. Clin Chem 20:57-60. 1974 9. Steige H. Jones JD: Evaluation of pneumatic tube system for delivery of blood specimens. Clin Chem 17:1160-1164, 1971
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
limited practical significance. Usually our blood specimens are sent through the system immediately following procurement so that changes in LDH do not occur (Tables 2, 3, and 5). Only when the hospital personnel were asked deliberately to introduce a 15min delay before sending the specimens was this effect seen. As there was not an associated increase in serum hemoglobin, interference with other tests seems unlikely. The increase in LDH unaccompanied by elevations of hemoglobin and K+ suggests that the erythrocytes were not the source, as hemoglobin4 and K+7 have been reported to be more sensitive indicators of physical trauma to erythrocytes. The performance of our blood specimen transport system is superior to those of systems previously reported. "•" The system has been operational for a year with rare interruptions in service and only occasional specimen losses through broken or spilled tubes. The transit time for specimens from critical care areas to the laboratory has been drastically reduced. The need for a special blood porter service for the emergency department no longer exists. Over a five-year period this will balance the installation cost of the system. The design of this system, although specific for our hospital, incorporates certain general features intended to minimize physical trauma to blood components. Of these, in our own experience, the padding of the landing site is critical. The transit speed within our system may be slower than necessary to prevent damage to blood components. We propose to investigate this when we extend the tube. Our current carrier velocity is limited by the weight of the carriers, so that increasing it would involve the introduction of lighter
HOSPITAL PNEUMATIC-TUBE SYSTEMS have been widely used for efficient transport of mail, drugs, and medical reports. In the first attempts to adapt these systems for blood transport, damage to the erythrocyte and other blood cells was encountered. Attempts to solve this problem have been made. 3 - 5,68 - 9 These efforts were applied to experimental models, and the closest to a functional system was the pilot project at the Erie County Laboratories. 8 A pneumatic-tube system incorporating structural modifications designed to reduce trauma to blood specimens was installed in our hospital. This paper describes these modifications and our experience with blood transport by this system. Materials and Methods Description of the System The pneumatic system for conveying blood samples at the Ottawa Civic Hospital was manufactured by the Mosler Airmatic Company. It is a unidirectional, continuously operating pneumatic-tube system dediReceived April II, 1977; received revised manuscript June 10, 1977; accepted for publication June 10, 1977. Address reprint requests to Dr. Smith: Division of Biochemistry, Department of Laboratory Medicine, Ottawa Civic Hospital, 1053 Carling Ave., Ottawa, Ontario K1Y 4E9, Canada.
Division of Biochemistry, Department of Laboratory Medicine Ottawa Civic Hospital, and the Departments of Biochemistry and Medicine of the University of Ottawa, Ottawa, Ontario, Canada
cated to specimen transport linking the emergency department and the intensive care unit with the biochemistry laboratory. The physical pathway of the tube travels 485 m through several connecting hospital buildings and rises and falls a total of four levels (Figs. 1 and 2). There is a buried underground section, as well as externally exposed portions that are coated and enclosed in mull wrap and moisture-proof insulation. This is important, as the carriers will jam if moisture condenses within the tube. In the future, the present system will be extended to the main operating areas and a newly constructed cardiac unit, creating a total circuit of about 833.3 m (see Fig. 1). The intracardiac portion of the extension was installed at the time the unit was built. Carriers are returned from the lab to their point of origin by our conventional pneumatictube system, also designed by Mosler Airmatic. The system was engineered to maintain the carriers at a constant speed (3.6 m/sec), regardless of load. This is significantly less than the usual velocity of pneumatic systems. The carriers are routed smoothly and automatically through gentle bends without the use of deflector arms. Deceleration of the carriers is controlled by an air brake. The landing site at the receiving station is well padded. As a safety feature, the system was designed to prevent access to the system when a carrier is in transit. Further, it is equipped with an alarm system, which is activated when a carrier becomes jammed. The carriers are constructed of plexiglas material with a leather hinge top-flap and at the opposite end a station selection control (Fig. 3D). This is electronically preset to return to the original sending station when the carrier is placed in the conventional system. No setting is necessary when the carrier is sent to the laboratory, as this is the only possible destination in our system. The carriers are color-coded so as not to be confused with carriers from the conventional system. The inserts are zipper-closed and padded with foam rubber, which holds the specimens snugly in
0002-9173/78/0800/0291 $00.75 © American Society of Clinical Pathologists
291
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
Poznanski, Wojciech, Smith, Frances, and Bodley, Frank: Implementation of a pneumatic-tube system for transport of blood specimens. Am J Clin Pathol 70: 291-295, 1978. Whole-blood specimens were transported through an installed 485-meter pneumatic-tube system dedicated to blood transport. The system featured constant-speed, low-carrier-velocity travel (3.6 m/sec) with controlled deceleration prior to arrival at its destination. Inserts were designed with ample use of padding to minimize agitation during transport and landing. Serum potassium, hemoglobin, and lactate dehydrogenase activity and whole-blood pH, PCo2> and P,,, were not altered in freshly drawn blood transported in this system. Partial filling or heparinization of the specimen containers did not alter the results. When specimens were allowed to clot prior to pneumatic-tube transport, significantly higher levels of serum lactate dehydrogenase were obtained. This study demonstrates that transport of whole-blood specimens by pneumatic tube without damage to blood components is feasible. (Key words: Blood specimen transport; Pneumatic tube; Nature of specimen.)
POZNANSKl, SMITH AND BODLEY
292
1
A.J.C.P. • August 1978
rf-STATON'S CARDIAC \ CARE
8SKtt»
STATIONS OPERATNG ROOM
FIG. 1. Plot diagram of hospital complex and pneumatic-tube system. Actual dedicated system: solid line; proposed system: broken line; conventional system stations: diamonds. Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
SWnON'3 EMERGENCY
STATIONS
H=FT
ELEVATION VEW
\t
STATION" 4
*!-
£
V r r r a l
\
J.
Onxnl Floor
STATION'S
STATION 1
FIG. 2. Model diagram of hospital complex and pathway of pneumatic-tube system.
Scale f-4G0'
LABORATORY SUGGESTIONS
Vol. 70 . No. 2
293
place (Fig. 3A). The outside diameter of the insert is cut so that there is no space for movement within the carrier. Normally the specimens are placed crosswise in the insert, no more than five per carrier. Blood Constituent
Measurement
The blood serum lactate dehydrogenase activity (LDH), sodium (Na + ), potassium (K + ), chloride (Cl~), carbon dioxide (C0 2 ), glucose, hemoglobin, and urea nitrogen, and whole-blood pYL and gases (P 02 , Pco2) were measured, because either they are frequently requested as emergency tests or they can provide evidence of cellular destruction, or both. Standard clinical laboratory procedures (Technicon SMA 6 and 12, Corning pH/Blood Gas 165) were employed for these determinations. Hemoglobin was measured according to the method of Harboe. 4 Standard statistical methods were employed. 1
Working Procedure Duplicate blood samples were drawn by venipuncture into 10-ml Vacutainer tubes* from patients in emergency or intensive care. The specimens were collected in plain, red-stoppered Vacutainers with the tubes filled to capacity unless otherwise specified. One tube was sent through the pneumatic system while the other was transported by porter to the laboratory. Upon receipt, the duplicate samples were processed together without special treatment. Clotting was allowed to come to completion, when necessary; Sure-Sep®t was applied to the clotted blood prior to centrifugation. Blood specimens for pH and gas determinations were collected in heparinized glass syringes, stoppered with syringe caps, wrapped in a * Becton-Dickinson. t General Diagnostics.
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
FIG. 3. Carrier and its insert. A, specimens being loaded into carrier insert. B, syringe wrapped in cold gel pack. C, syringe being loaded into carrier insert. D, insert being placed inside carrier.
POZNANSKl, SMITH AND BODLEY
294
Table I. Reproducibility of Methods C.V. Test
Mean*
± SD
(%)
Glucose (mmol/l) Urea nitrogen (mmol/l) Na + (mmol/l) K+ (mmol/l) CO, (mmol/l) CI (mmol/l) Lactate dehydrogenase (ug/1) Hemoglobin (g/l)t P,-„, (mm Hg) PH P,„ (mm Hg)
5.775 7.50 127.4 3.78 12.7 109.5 235.4 0.141 36.3 7.411 102.0
0.165 0.18 1.2 0.06 0.8 1.1 8.9 0.011 1.9 0.009 5.9
2.9 2.4 1.0 1.6 6.3 1.0 3.8 7.8 5.3 0.1 5.8
* n = 30. t n = 20.
Test
Porter (Mean*)
Tube (Mean*)
d
SE Diff.
Glucose (mmol/l) Urea nitrogen (mmo 1/D Na + (mmol/l) K + (mmol/l) C 0 2 (mmol/l) CI" (mmol/l) Lactate dehydrogen;ase (u/l) Hemoglobin (g/l)
7.246 9.19 137.9 4.19 27.9 99.3 303.0 0.077
7.324 9.23 137.8 4.18 28.5 100.8 307.2 0.103
0.078 0.04 0.1 0.01 0.6t 1.5t 4.2 0.026
0.125 0.05 0.3 0.02 0.2 0.6 5.0 0.019
seen to conform to acceptable laboratory standards.2 Except for hemoglobin, quality control sera were analyzed and the between-assay precision calculated. For hemoglobin the within-run precision was determined using a patient sample. In Table 2 the effects of pneumatic-tube blood transport on various serum constituents are shown. Other than slightly higher values for total C0 2 and Cl~ obtained for specimens transported through the system, no effect was detected. The effect of variation in the nature of the specimen collected was investigated. As shown in Table 3, the presence of partly filled tubes or heparinized blood did not alter the serum chemistry results. Transport of fully clotted blood through the system was associated with a definite elevation in serum LDH. Blood-gas and pH measurements were performed on whole-blood specimens collected and transported in heparinized glass syringes. No difficulty in transport arose. The test results were not affected by transport of the blood through the pneumatic tube (Table 4). The existing portion of the blood transport tube within the cardiac unit was evaluated. This segment is only 67 m long and at present is designed to transport specimens at 5.6 m/sec. As shown in Table 5, the greater transport speed over this shorter distance did not affect the test results.
* n = 35. t Difference statistically signiificant. P = 0.05.
Discussion
cold gel pack placed singly in the inserts, and sent immediately (Figs. 7>B, 3C). Results The reproducibility of our analytic methods during the study period is presented in Table 1, and may be
Our results indicate that routine transport of blood specimens by pneumatic tube is feasible. The small differences in total C0 2 and Cl~ associated with pneumatic-tube transport do not appear clinically important. The elevation of LDH associated with the transport of clotted blood through the pneumatic system is of
Table 3. Effect of Nature of Specimen on Test Result Test*
Specimen
Control (Mean)
Tube (Mean)
d
t§
Plain Vacutainer sent immediatelyt (n = 22)
K+ Hemoglobin Lactate dehydrogenase
3.98 0.086 167.5
4.02 0.081 172.0
0.04 0.005 4.5
0.784 0.475 1.692
Half-filled plain Vacutainer sent immediatelyt (n = 8)
K+ Hemoglobin Lactate dehydrogenase
4.09 0.243 198.0
4.00 0.144 192.2
0.09 0.099 5.8
1.645 0.961 0.528
Filled plain Vacutainer sent after 15 minutest (n = 23)
K+ Hemoglobin Lactate dehydrogenase
3.85 0.108 233.1
3.84 0.110 264.3
0.01 0.002 31.2
0.333 0.192 2.966'
Filled heparinized Vacutainer sent immediatelyt (n = 24)
K+ Hemoglobin Lactate dehydrogenase
3.83 0.051 189.0
3.80 0.036 195.5
0.03 0.015 6.5
0.515 1.235 0.699
* Units are K \ mmol/l; hemoglobin, g/l; lactate dehydrogenase, ug/1. t Control is completely filled plain Vacutainer sent by porter. t Control is completely filled heparinized Vacutainer sent by porter.
§ Student's t test for paired data.
V < o.oi.
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
Table 2. Effects of Blood Transport Through the Pneumatic-tube System
A.J.C.P. • August 1978
LABORATORYSUGGESTIONS
vol. 70 . No. 2
295
Table 5. Effect of Transport Through Cardiac Unit Tube
Table 4. Effects of Pneumatic-tube Transport on pH and Blood-gas Results Test
Porter (Mean*)
Tube (Mean*)
a
SE Diff.
Test
Porter (Mean*)
Tube (Mean*)
d
SE Diff.
Pro, (mm Hg) P„, (mm Hg)
7.420 39.8 96.2
7.421 39.2 94.8
0.001 0.6 1.4
0.003 0.9 3.6
Glucose (mmol/1) Urea nitrogen (mmol/1) Na+ (mmol/1) K+(mmol/1) C0 2 (mmol/1) CI" (mmol/1) Lactate dehydrogenase (/i.g/1)
6.567 6.10 138.4 4.46 27.7 99.2 255.4
6.496 6.10 138.7 4.44 27.6 99.2 258.0
0.071 0 0.3 0.02 0.1 0 2.6
0.934 0 0.2 0.03 0.1 0 3.6
* n •- 43.
* n = 56.
carriers. The safety lockout may prove undesirable as utilization of the system increases, but this feature can be modified. As technology in this field advances, the development of pneumatic systems capable of transporting both blood specimens and other materials within hospitals seems probable. Acknowledgments. The Administrators and the Department of Planning and Development of the Ottawa Civic Hospital assisted in this project.
References 1. Bradford Hill A: Principles of Medical Statistics. Ninth edition. New York, Oxford University Press, 1971. p 390 2. Crosswell MA: How useful is the clinical chemistry laboratory. Lab-Lore 6:353-356, 1975 3. Delbruck A, Porchman H: Uber den einfluss des rohrposttransportes auf klinischen untersuchungsmaterial unter verschiedenen betriebsbedingungen. Klin Chem Klin Biochem 6:211-216, 1968 4. Harboe M: A method for determination of hemoglobin in plasma by near-ultraviolet spectrophotometry. Scand J Clin Lab Invest 11:66-70. 1959 5. Lapidus BM, Dehner GF: Gravity delivery of laboratory specimens. Am J Clin Pathol 64:127-135, 1975 6. McClellan EK, Nakamura RM, Haas W, et al: Effect of pneumatic tube transport system on the validity of determinations in blood chemistry. Am J Clin Pathol 42:152-155, 1964 7. Peckauskas RA. Portnoy AL, Narayanan S: Investigations into the biochemical changes in the red cell membrane following irradiation of plasma. Abstracts IX Intern. Cong. Clin. Chem. 81. 1975 8. Pragay DA, Edwards L, Toppin M. et al: Evaluation of an improved pneumatic tube system suitable for transportation of blood specimens. Clin Chem 20:57-60. 1974 9. Steige H. Jones JD: Evaluation of pneumatic tube system for delivery of blood specimens. Clin Chem 17:1160-1164, 1971
Downloaded from http://ajcp.oxfordjournals.org/ by guest on March 19, 2016
limited practical significance. Usually our blood specimens are sent through the system immediately following procurement so that changes in LDH do not occur (Tables 2, 3, and 5). Only when the hospital personnel were asked deliberately to introduce a 15min delay before sending the specimens was this effect seen. As there was not an associated increase in serum hemoglobin, interference with other tests seems unlikely. The increase in LDH unaccompanied by elevations of hemoglobin and K+ suggests that the erythrocytes were not the source, as hemoglobin4 and K+7 have been reported to be more sensitive indicators of physical trauma to erythrocytes. The performance of our blood specimen transport system is superior to those of systems previously reported. "•" The system has been operational for a year with rare interruptions in service and only occasional specimen losses through broken or spilled tubes. The transit time for specimens from critical care areas to the laboratory has been drastically reduced. The need for a special blood porter service for the emergency department no longer exists. Over a five-year period this will balance the installation cost of the system. The design of this system, although specific for our hospital, incorporates certain general features intended to minimize physical trauma to blood components. Of these, in our own experience, the padding of the landing site is critical. The transit speed within our system may be slower than necessary to prevent damage to blood components. We propose to investigate this when we extend the tube. Our current carrier velocity is limited by the weight of the carriers, so that increasing it would involve the introduction of lighter
