- Email: [email protected]
Pneumatic Tube Delivery System for Blood Samples Reduces Turnaround Times Without Affecting Sample Quality
RESEARCH
Pneumatic Tube Delivery System for Blood Samples Reduces Turnaround Times Without Affecting Sample Quality Authors: Christopher M.B. Fernandes, MD, Andrew Worster, MD, Kevin Eva, PhD, Stephen Hill, PhD, and Catherine McCallum, ART, Hamilton, Ontario, Canada
Christopher M.B. Fernandes is Professor and Head of Emergency Medicine, McMaster University, Hamilton, Ontario, Canada. Andrew Worster is Clinical Assistant Professor, Emergency Medicine, Hamilton Health Sciences and McMaster University, and Clinical Assistant Professor, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada. Kevin Eva is Assistant Professor, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada. Stephen Hill is Assistant Professor, Hamilton Regional Laboratory Medicine Program and Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada. Catherine McCallum is Quality Manager, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada. Presented at the American College of Emergency Physicians Research Forum, Boston, Massachusetts, October 2003. For correspondence, write: Christopher M.B. Fernandes, Professor and Head of Emergency Medicine, McMaster University, 237 Barton St East, Hamilton, ON, l8l 2x2, Canada; E-mail: [email protected]. J Emerg Nurs 2006;32:139-43. 0099-1767/$32.00 Copyright n 2006 by the Emergency Nurses Association. doi: 10.1016/j.jen.2005.11.013
Study objectives: In this study, blood samples from ED pa-
tients that were delivered to the laboratory by a pneumatic tube delivery system and by a human courier were compared for timeliness and quality of results. Methods: We studied all consecutive measurements of serum hemoglobin and potassium ordered from 2 emergency departments of a multisite tertiary care hospital system, one with a pneumatic tube system and the other using human couriers. Turnaround time was measured from the time that the test was ordered by the physician to the time the result was reported on the hospital information system. Hemolysis was measured with use of a standardized, validated method. Analysis: Times were normalized by log transformation (ln
[minutes + 1]), and a comparison of sites was conducted using analysis of variance. Hemolysis rates of the 2 delivery systems were compared by m2. Results: There was no significant difference in hemolysis rate between the 2 methods of delivery (7/121 [5.79%] with a pneumatic tube system and 20/200 [10%] with a human courier). When delivered with a pneumatic tube system, the mean turnaround times (with ranges) for both hemoglobin (33 minutes [4-230]) and potassium (64 [34-208]) were shorter than those delivered by a human courier (43 minutes [3-150] and 72 [28-213], respectively). Conclusion: The use of a pneumatic tube delivery system for
transporting blood samples from the emergency department to the laboratory can significantly reduce the turnaround times of results without a reduction in sample quality.
April 2006
32:2
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I
n this era of overcrowding, any potential for delay must be redressed, including laboratory turnaround times. The College of American Pathologists’ QProbes Study, based on 40,000 specimens per analyte at 700 institutions,1 identified the turnaround time (TAT) from phlebotomy to reporting of results as the ‘‘most important characteristic for stat laboratory testing’’ and provided TATs for various laboratory tests. These TATs have been used as external benchmarks to which the TATs for hemoglobin and potassium at individual institutions have been compared and root cause analyses performed to determine points of delay.2,3 Although delays in TATs often are a result of process issues, they also can be related to design and equipment factors. The method of delivery of the blood samples to the laboratory is one such factor that has the potential to have an impact on both TAT and sample quality.4-9 The pneumatic tube system (PTS) has been reported to be a rapid and reliable method of transporting small materials such as specimens and medications between hospital departments, thereby eliminating the need for human couriers.10 However, the PTS also has been implicated as a cause for hemolysis of transported blood specimens.6,7 Hemolysis is a key issue with these samples, because it may induce falsely elevated potassium levels and necessitate repeat collection and measurement of blood specimens, thereby increasing the overall TATs. The objectives of this study were to compare the TATs of 2 commonly performed ED blood tests, serum potassium and hemoglobin, as well as the hemolysis rates of the samples transported from the emergency department to the laboratory by a PTS and those transported by human courier. We hypothesized that a PTS reduces TAT without reduction in sample quality. Methods
ETHICS
This quality assessment study did not involve human subjects or experiments and therefore was deemed by our hospital and university Review Ethics Board to be exempt from formal approval. Identification of blood samples was removed as the data for each sample were entered into a computer database for analysis. This process maintained the confidentiality of patient information by eliminating all patient identifiers from each sample.
140
SETTING
The setting was 2 emergency departments of a multisite, tertiary care, academic medical center staffed by a single group of full-time emergency physicians. Site 1 has an annual volume of 39,500 visits, 64.0% of which are triaged as resuscitation, emergent, or urgent (ie, levels 1 to 3 of a 5level triage acuity scale),11 and a 15.8% admission rate. Site 2 has an annual volume of 28,500 visits, 46.2% of which are triaged as levels 1 to 3, and a 15.2% admission rate. Site 1 has a PTS, the TransLogic CTS-20. This computercontrolled, branched system of 15-cm diameter tubes traverses one f loor and has only one transfer station. Samples are placed in a plastic container known as a carrier that consists of high-impact resistant polycarbonate and contains removable padded liners. The system transports the carrier (one at a time) at an average speed of 7.6 meters (25 feet) per second using positive and negative air pressure and transfer stations to determine the direction of travel. Upon arrival at a destination station, the carrier is decelerated by an air cushion and dropped gently into a receiving bin.10 Site 2 has no PTS; therefore, a health care aide must be called on a regular basis to transport laboratory specimens for analysis. Other than the method of delivery of the samples to the laboratory, the process from physician ordering to reporting the results on the hospital information system is identical at both sites, including the laboratory equipment on which the samples are measured: serum potassium levels were measured using a Roche Integra 700 (Roche Diagnostics, Laval, Quebec), and hemoglobin levels were measured using a Coulter Gen-S (BeckmanCoulter, Inc, Brea, Calif.) (Figure 1).2 Hemolysis was measured by visual inspection of the specimens using a 4-point validated Likert scale based on the plasma hemoglobin concentration. Hemolysis was defined a priori as greater than 0 g/L of hemoglobin in the plasma such that samples with greater than 5 g/L were rejected and, when necessary, the samples were recollected. The proportion of serum potassium samples hemolyzed is reported as percent of total potassium samples. Turnaround time for this study was measured from the time that the test was ordered by the physician to the time the result was reported on the hospital information system.
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START
T1
EP ORDERS LAB TEST (S)
TABLE 1 Turnaround times for blood tests in the emergency department
-STAT vs Not STAT ED 20% STAT 75% Urgent 5% Rountine
ACUITY & LOCATION
Turnaround times
-
-
ORDER PROCESSED
workload (RN) #MD’s Housestaff No medical directives Tests referred out
WAIT
- Order wait: no one to process volume of orders - Staff workload
ORDER PROCESSED
RN DRAWS SAMPLE
T2
T2
RN DRAWS SAMPLE
PLACED IN TUBE
T3
T3
PLACED IN TUBE
-
WAIT
WAIT
Tube (min)
Human (min)
P value
33 4-230 64 34-208
43 3-150 72 28-213
b.001 NA b.001 NA
NON-ACUTE
ACUTE
Portering Tube system down Lack of tubes
WAIT
WAIT
T4
Hemoglobin: mean Hemoglobin: range Potassium: mean Potassium: range NA, Not applicable.
test was performed on the hemolysis rates. Central tendency and dispersion were described using mean values and ranges. Where appropriate, 95% confidence intervals were calculated to illustrate data precision.
LAB RECEPTION ARRIVAL
T5
Results
SAMPLES & LABELS CHECKED & LOGGED IN
- Tube sits at reception: volume of workload # of personnel
WAIT
T6
CENTRIFUGE ?
INSTRUMENT
WAIT CENTRIFUGE
RESULTS REVIEWED &VERIFIED
Turnaround Times T2 – T7 T1 – T8
INSTRUMENT T6 T7-results reported
MEDITECH REPORT
Lab ED
RESULT IN ED
T8
- Transport of results to appropriate area - Printer locatiom
Table 1 illustrates that the turnaround time for hemoglobin was significantly less than that for serum potassium (F[1,660] = 406, P b .001). More importantly for the current discussion, the same table illustrates that the turnaround time for the PTS was significantly less than that of a human courier system (F[1,66] = 136, P b .001). Finally, the hemolysis rate of 7/121 (5.8%) observed with a PTS did not differ from the rate of 20/200 (10%) observed with a human courier (m2 = .174, P N .15).
END
Discussion
FIGURE 1
ED/lab process. SAMPLING
This cross-sectional study examined TATs for all consecutive stat hemoglobin and serum potassium measurements during an 8-day period at each site. Patient identifiers were removed from each sample and replaced by sequential numeric identifiers to ensure confidentiality. We proposed a minimal clinically significant difference in mean and median TATs of 10 minutes and an absolute increase in hemolysis rate of 10%. ANALYSES
A log transformation (ln minutes + 1) was performed to normalize TAT data. An analysis of variance was performed on the normalized turnaround time data and a m2
April 2006
32:2
The results of this study demonstrate that transportation of blood specimens from the emergency department to the laboratory via a PTS can be time effective without compromising the quality of the samples. A previous study simultaneously comparing TATs via a human courier and a PTS found no statistical difference between the two.6 However, students were employed specifically for the purpose of carrying the specimens to the laboratory in that study, presumably as soon as the specimens were ready. In our study, the delivery of hand-carried specimens was dependent on the availability of a health care aide, and thus specimens could sit for significant periods awaiting pickup. The lack of significant difference in hemolysis rates between the 2 transportation methods contradicts previous reports that a PTS would have a higher hemolysis rate than
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other methods of transfer because of the rapid acceleration and deceleration.5,7 However, there are several determinants of whether the results of a blood specimen are altered when transported via a PTS. These determinants include but are not limited to: (1) the volume of blood in the vacutainer7,12,13; (2) the type of PTS used7,12,13; (3) the distance and routing of the PTS7,12,13; and (4) cushioning of the container.7,12,13 The PTS in this study (TransLogic CTS20) has only one transfer station, traverses only one f loor, and participating staff in the study were unaware of the modifying factors. Sample quality is definitely an issue when delays in tests and repetition of tests due to hemolysis delay patient disposition. Is this significant? When we examine causes for ED overcrowding, we must consider the multiple factors that result in patient waits and delays. It is traditional to blame delays in moving admitted patients out of the emergency department as the sole cause for overcrowding. However, without negating the very significant effect from this fact, we also must identify and deal with other causes.14 This finding has practice implications. We suggest that use of a PTS can reduce TATs, contributing to a reduced length of stay for ED patients. This study has some limitations. It is specific to one institution and may need replication in other settings and systems. Second, we must consider a possible Hawthorne effect, because staff were aware of this study in that times were being recorded, but they remained unaware of the purpose and hypothesis. Also, it is unlikely that this effect would have been significant, given the 8-day study period with rotating staff in both departments. This study did not evaluate the total amount of time that the PTS is inoperational because of maintenance and mechanical failure or the need for many of the tests ordered. It should be noted that our definition of TAT allows for time lapses that might be considerable and unrelated to either transport system. For example, an hour might have elapsed from time of physician order until phlebotomy, or the specimen may have sat unattended prior to being placed in the PTS or a human courier being notified. What kind of solutions can be implemented? If possible, it would seem that implementation of a PTS must be seriously considered in any emergency department aiming at competitive TATs. A previous Q-Probes Study suggested that the following could be generalized to any
142
emergency department to reduce TATZdelivery of each specimen as it is collected, direct delivery route, continuous rather than batch testing, and pneumatic tube delivery system.8 Other studies have supported this central laboratory approach, using a TS, as more cost-effective and faster than the traditional satellite laboratory system.4 ED point-of-care testing also has been suggested as an option to improve TAT. It may be worth considering in the future. However, because this type of testing generally requires whole blood and may not cover all analytes, it remains problematic in the current environment.15 The most efficient improvement in laboratory TATs may be ultimately related to elimination of unnecessary tests. Conclusion
The use of a pneumatic tube delivery system for transporting blood samples from the emergency department to the laboratory can significantly reduce the TATs of results without a reduction in sample quality. REFERENCES 1. Howanitz P, Steindel S, Cembrowski G, Long T. Emergency department stat test turnaround times. Arch Pathol Lab Med 1992;116:122-8. 2. Fernandes CMB, Worster A, Hill S, McCallum C, Eva K. Root cause analysis of delays for laboratory tests on emergency department patients. Can J Emerg Med 2004;6:116-22. 3. Fernandes CMB, Walker R, Price A, Marsden J, Haley L. Root cause analysis of laboratory delays to an emergency department. J Emerg Med 1997;15:735-9. 4. Green M. Successful alternatives to alternate site testing. Use of a pneumatic tube system to the central laboratory. Arch Pathol Lab Med 1995;119:943-7. 5. Pragay D, Edwards D, Toppin M, Palmer R, Chilcote M. Evaluation of an improved pneumatic-tube system suitable for transportation of blood specimens. Clin Chem 1974:57-60. 6. Stair TO, Howell JM, Fitzgerald DJ, Bailey SC, Bastasch MD. Hemolysis of blood specimens transported from ED to laboratory by pneumatic tube. Am J Emerg Med 1995;13:484. 7. Steige H, Jones J. Evaluation of pneumatic tube systems for delivery of blood specimens. Clin Chem 1971;17:1160-4. 8. Dale JC, Steindel SJ, Walsh M. Early morning blood collections: a College of American Pathologists Q-Probes Study of 657 institutions. Arch Pathol Lab Med 1998;122:865-70. 9. Collinson PO, John CM, Gaze DC, Ferrigan LF, Cramp DG. Changes in blood gas samples produced by a pneumatic tube system. J Clin Pathol 2002;55:105-7. 10. Keshgegian A, Bull G. Evaluation of a soft-handling computerized pneumatic tube specimen delivery system. Am J Clin Pathol 1992;97:535-40.
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11. Beveridge R, Clarke B, Janes L, Savage N, Thompson J, Dodd G, et al. Canadian Emergency Department Triage and Acuity Scale (CTAS) Implementation Guidelines. Can J Emerg Med 1999; 1(3 suppl). 12. McClellan E, Nakamura R, Haas W, Moyer D, Kunitake G. Effect of pneumatic tube transport system on the validity of determinations in blood chemistry. Am J Clin Pathol 1964;42: 152-5.
13. Delbruck A, Poschmann H. [On the inf luence of pneumatic post transport on clinical investigation material under different operating conditions]. Z Klin Chem Klin Biochem 1968;6:211-6. 14. Fernandes CMB. Emergency department overcrowding: what is our response to the ‘‘New Normal’’? Acad Emerg Med 2003;10: 1096-7. 15. Altieri M, Camarca M. Point of care testing. Clin Pediatr Emerg Med 2001;2:275-9.
Clarification In the December 2005 and February 2006 issues of JEN, Iris Frank, RN, MSN, was the section editor of the compilations, ‘‘Emergency Response to the Gulf Coast Devastation by Hurricanes Katrina and Rita: Experiences and Impressions.’’ The authors of the Katrina articles were as follows: December 2005;31(6):526 ] 47 Mikki Grit, RN April Wood, RN, EMT Jennifer Crate, RN, CEN Bob McBride, RN Tim Butcher, RN, BSN, EMT-P Sue Connell, RN Curt Audin, RN Kerry Jeanice, RN, EMT-P Robin Page, RN, CEN Bernie Heilicser, DO Mary Connelly, RN, CEN Jo Ann Edwards, RN Knox Andress, RN Sharon Cohen, RN, CNS Karen To’oto’o, RN, BS
February 2006;32(1):56 ] 62 Nancy Chiocchi, RN, MSN Helen Sandkuhl, RN, MSN, CEN, TNS, FAEN Joan Eberhardt, RN, BSN, MA, CCRN, FAEN Virginia Myerscough, RN, BSN, CEN Scott Howard, RN
The editors are grateful to all of the contributors who shared their stories and furthered our understanding of the events that unfolded in the aftermath of Hurricane Katrina.
April 2006
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Pneumatic Tube Delivery System for Blood Samples Reduces Turnaround Times Without Affecting Sample Quality Authors: Christopher M.B. Fernandes, MD, Andrew Worster, MD, Kevin Eva, PhD, Stephen Hill, PhD, and Catherine McCallum, ART, Hamilton, Ontario, Canada
Christopher M.B. Fernandes is Professor and Head of Emergency Medicine, McMaster University, Hamilton, Ontario, Canada. Andrew Worster is Clinical Assistant Professor, Emergency Medicine, Hamilton Health Sciences and McMaster University, and Clinical Assistant Professor, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada. Kevin Eva is Assistant Professor, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada. Stephen Hill is Assistant Professor, Hamilton Regional Laboratory Medicine Program and Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada. Catherine McCallum is Quality Manager, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada. Presented at the American College of Emergency Physicians Research Forum, Boston, Massachusetts, October 2003. For correspondence, write: Christopher M.B. Fernandes, Professor and Head of Emergency Medicine, McMaster University, 237 Barton St East, Hamilton, ON, l8l 2x2, Canada; E-mail: [email protected]. J Emerg Nurs 2006;32:139-43. 0099-1767/$32.00 Copyright n 2006 by the Emergency Nurses Association. doi: 10.1016/j.jen.2005.11.013
Study objectives: In this study, blood samples from ED pa-
tients that were delivered to the laboratory by a pneumatic tube delivery system and by a human courier were compared for timeliness and quality of results. Methods: We studied all consecutive measurements of serum hemoglobin and potassium ordered from 2 emergency departments of a multisite tertiary care hospital system, one with a pneumatic tube system and the other using human couriers. Turnaround time was measured from the time that the test was ordered by the physician to the time the result was reported on the hospital information system. Hemolysis was measured with use of a standardized, validated method. Analysis: Times were normalized by log transformation (ln
[minutes + 1]), and a comparison of sites was conducted using analysis of variance. Hemolysis rates of the 2 delivery systems were compared by m2. Results: There was no significant difference in hemolysis rate between the 2 methods of delivery (7/121 [5.79%] with a pneumatic tube system and 20/200 [10%] with a human courier). When delivered with a pneumatic tube system, the mean turnaround times (with ranges) for both hemoglobin (33 minutes [4-230]) and potassium (64 [34-208]) were shorter than those delivered by a human courier (43 minutes [3-150] and 72 [28-213], respectively). Conclusion: The use of a pneumatic tube delivery system for
transporting blood samples from the emergency department to the laboratory can significantly reduce the turnaround times of results without a reduction in sample quality.
April 2006
32:2
JOURNAL OF EMERGENCY NURSING
139
RESEARCH/Fernandes et al
I
n this era of overcrowding, any potential for delay must be redressed, including laboratory turnaround times. The College of American Pathologists’ QProbes Study, based on 40,000 specimens per analyte at 700 institutions,1 identified the turnaround time (TAT) from phlebotomy to reporting of results as the ‘‘most important characteristic for stat laboratory testing’’ and provided TATs for various laboratory tests. These TATs have been used as external benchmarks to which the TATs for hemoglobin and potassium at individual institutions have been compared and root cause analyses performed to determine points of delay.2,3 Although delays in TATs often are a result of process issues, they also can be related to design and equipment factors. The method of delivery of the blood samples to the laboratory is one such factor that has the potential to have an impact on both TAT and sample quality.4-9 The pneumatic tube system (PTS) has been reported to be a rapid and reliable method of transporting small materials such as specimens and medications between hospital departments, thereby eliminating the need for human couriers.10 However, the PTS also has been implicated as a cause for hemolysis of transported blood specimens.6,7 Hemolysis is a key issue with these samples, because it may induce falsely elevated potassium levels and necessitate repeat collection and measurement of blood specimens, thereby increasing the overall TATs. The objectives of this study were to compare the TATs of 2 commonly performed ED blood tests, serum potassium and hemoglobin, as well as the hemolysis rates of the samples transported from the emergency department to the laboratory by a PTS and those transported by human courier. We hypothesized that a PTS reduces TAT without reduction in sample quality. Methods
ETHICS
This quality assessment study did not involve human subjects or experiments and therefore was deemed by our hospital and university Review Ethics Board to be exempt from formal approval. Identification of blood samples was removed as the data for each sample were entered into a computer database for analysis. This process maintained the confidentiality of patient information by eliminating all patient identifiers from each sample.
140
SETTING
The setting was 2 emergency departments of a multisite, tertiary care, academic medical center staffed by a single group of full-time emergency physicians. Site 1 has an annual volume of 39,500 visits, 64.0% of which are triaged as resuscitation, emergent, or urgent (ie, levels 1 to 3 of a 5level triage acuity scale),11 and a 15.8% admission rate. Site 2 has an annual volume of 28,500 visits, 46.2% of which are triaged as levels 1 to 3, and a 15.2% admission rate. Site 1 has a PTS, the TransLogic CTS-20. This computercontrolled, branched system of 15-cm diameter tubes traverses one f loor and has only one transfer station. Samples are placed in a plastic container known as a carrier that consists of high-impact resistant polycarbonate and contains removable padded liners. The system transports the carrier (one at a time) at an average speed of 7.6 meters (25 feet) per second using positive and negative air pressure and transfer stations to determine the direction of travel. Upon arrival at a destination station, the carrier is decelerated by an air cushion and dropped gently into a receiving bin.10 Site 2 has no PTS; therefore, a health care aide must be called on a regular basis to transport laboratory specimens for analysis. Other than the method of delivery of the samples to the laboratory, the process from physician ordering to reporting the results on the hospital information system is identical at both sites, including the laboratory equipment on which the samples are measured: serum potassium levels were measured using a Roche Integra 700 (Roche Diagnostics, Laval, Quebec), and hemoglobin levels were measured using a Coulter Gen-S (BeckmanCoulter, Inc, Brea, Calif.) (Figure 1).2 Hemolysis was measured by visual inspection of the specimens using a 4-point validated Likert scale based on the plasma hemoglobin concentration. Hemolysis was defined a priori as greater than 0 g/L of hemoglobin in the plasma such that samples with greater than 5 g/L were rejected and, when necessary, the samples were recollected. The proportion of serum potassium samples hemolyzed is reported as percent of total potassium samples. Turnaround time for this study was measured from the time that the test was ordered by the physician to the time the result was reported on the hospital information system.
JOURNAL OF EMERGENCY NURSING
32:2
April 2006
RESEARCH/Fernandes et al
START
T1
EP ORDERS LAB TEST (S)
TABLE 1 Turnaround times for blood tests in the emergency department
-STAT vs Not STAT ED 20% STAT 75% Urgent 5% Rountine
ACUITY & LOCATION
Turnaround times
-
-
ORDER PROCESSED
workload (RN) #MD’s Housestaff No medical directives Tests referred out
WAIT
- Order wait: no one to process volume of orders - Staff workload
ORDER PROCESSED
RN DRAWS SAMPLE
T2
T2
RN DRAWS SAMPLE
PLACED IN TUBE
T3
T3
PLACED IN TUBE
-
WAIT
WAIT
Tube (min)
Human (min)
P value
33 4-230 64 34-208
43 3-150 72 28-213
b.001 NA b.001 NA
NON-ACUTE
ACUTE
Portering Tube system down Lack of tubes
WAIT
WAIT
T4
Hemoglobin: mean Hemoglobin: range Potassium: mean Potassium: range NA, Not applicable.
test was performed on the hemolysis rates. Central tendency and dispersion were described using mean values and ranges. Where appropriate, 95% confidence intervals were calculated to illustrate data precision.
LAB RECEPTION ARRIVAL
T5
Results
SAMPLES & LABELS CHECKED & LOGGED IN
- Tube sits at reception: volume of workload # of personnel
WAIT
T6
CENTRIFUGE ?
INSTRUMENT
WAIT CENTRIFUGE
RESULTS REVIEWED &VERIFIED
Turnaround Times T2 – T7 T1 – T8
INSTRUMENT T6 T7-results reported
MEDITECH REPORT
Lab ED
RESULT IN ED
T8
- Transport of results to appropriate area - Printer locatiom
Table 1 illustrates that the turnaround time for hemoglobin was significantly less than that for serum potassium (F[1,660] = 406, P b .001). More importantly for the current discussion, the same table illustrates that the turnaround time for the PTS was significantly less than that of a human courier system (F[1,66] = 136, P b .001). Finally, the hemolysis rate of 7/121 (5.8%) observed with a PTS did not differ from the rate of 20/200 (10%) observed with a human courier (m2 = .174, P N .15).
END
Discussion
FIGURE 1
ED/lab process. SAMPLING
This cross-sectional study examined TATs for all consecutive stat hemoglobin and serum potassium measurements during an 8-day period at each site. Patient identifiers were removed from each sample and replaced by sequential numeric identifiers to ensure confidentiality. We proposed a minimal clinically significant difference in mean and median TATs of 10 minutes and an absolute increase in hemolysis rate of 10%. ANALYSES
A log transformation (ln minutes + 1) was performed to normalize TAT data. An analysis of variance was performed on the normalized turnaround time data and a m2
April 2006
32:2
The results of this study demonstrate that transportation of blood specimens from the emergency department to the laboratory via a PTS can be time effective without compromising the quality of the samples. A previous study simultaneously comparing TATs via a human courier and a PTS found no statistical difference between the two.6 However, students were employed specifically for the purpose of carrying the specimens to the laboratory in that study, presumably as soon as the specimens were ready. In our study, the delivery of hand-carried specimens was dependent on the availability of a health care aide, and thus specimens could sit for significant periods awaiting pickup. The lack of significant difference in hemolysis rates between the 2 transportation methods contradicts previous reports that a PTS would have a higher hemolysis rate than
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other methods of transfer because of the rapid acceleration and deceleration.5,7 However, there are several determinants of whether the results of a blood specimen are altered when transported via a PTS. These determinants include but are not limited to: (1) the volume of blood in the vacutainer7,12,13; (2) the type of PTS used7,12,13; (3) the distance and routing of the PTS7,12,13; and (4) cushioning of the container.7,12,13 The PTS in this study (TransLogic CTS20) has only one transfer station, traverses only one f loor, and participating staff in the study were unaware of the modifying factors. Sample quality is definitely an issue when delays in tests and repetition of tests due to hemolysis delay patient disposition. Is this significant? When we examine causes for ED overcrowding, we must consider the multiple factors that result in patient waits and delays. It is traditional to blame delays in moving admitted patients out of the emergency department as the sole cause for overcrowding. However, without negating the very significant effect from this fact, we also must identify and deal with other causes.14 This finding has practice implications. We suggest that use of a PTS can reduce TATs, contributing to a reduced length of stay for ED patients. This study has some limitations. It is specific to one institution and may need replication in other settings and systems. Second, we must consider a possible Hawthorne effect, because staff were aware of this study in that times were being recorded, but they remained unaware of the purpose and hypothesis. Also, it is unlikely that this effect would have been significant, given the 8-day study period with rotating staff in both departments. This study did not evaluate the total amount of time that the PTS is inoperational because of maintenance and mechanical failure or the need for many of the tests ordered. It should be noted that our definition of TAT allows for time lapses that might be considerable and unrelated to either transport system. For example, an hour might have elapsed from time of physician order until phlebotomy, or the specimen may have sat unattended prior to being placed in the PTS or a human courier being notified. What kind of solutions can be implemented? If possible, it would seem that implementation of a PTS must be seriously considered in any emergency department aiming at competitive TATs. A previous Q-Probes Study suggested that the following could be generalized to any
142
emergency department to reduce TATZdelivery of each specimen as it is collected, direct delivery route, continuous rather than batch testing, and pneumatic tube delivery system.8 Other studies have supported this central laboratory approach, using a TS, as more cost-effective and faster than the traditional satellite laboratory system.4 ED point-of-care testing also has been suggested as an option to improve TAT. It may be worth considering in the future. However, because this type of testing generally requires whole blood and may not cover all analytes, it remains problematic in the current environment.15 The most efficient improvement in laboratory TATs may be ultimately related to elimination of unnecessary tests. Conclusion
The use of a pneumatic tube delivery system for transporting blood samples from the emergency department to the laboratory can significantly reduce the TATs of results without a reduction in sample quality. REFERENCES 1. Howanitz P, Steindel S, Cembrowski G, Long T. Emergency department stat test turnaround times. Arch Pathol Lab Med 1992;116:122-8. 2. Fernandes CMB, Worster A, Hill S, McCallum C, Eva K. Root cause analysis of delays for laboratory tests on emergency department patients. Can J Emerg Med 2004;6:116-22. 3. Fernandes CMB, Walker R, Price A, Marsden J, Haley L. Root cause analysis of laboratory delays to an emergency department. J Emerg Med 1997;15:735-9. 4. Green M. Successful alternatives to alternate site testing. Use of a pneumatic tube system to the central laboratory. Arch Pathol Lab Med 1995;119:943-7. 5. Pragay D, Edwards D, Toppin M, Palmer R, Chilcote M. Evaluation of an improved pneumatic-tube system suitable for transportation of blood specimens. Clin Chem 1974:57-60. 6. Stair TO, Howell JM, Fitzgerald DJ, Bailey SC, Bastasch MD. Hemolysis of blood specimens transported from ED to laboratory by pneumatic tube. Am J Emerg Med 1995;13:484. 7. Steige H, Jones J. Evaluation of pneumatic tube systems for delivery of blood specimens. Clin Chem 1971;17:1160-4. 8. Dale JC, Steindel SJ, Walsh M. Early morning blood collections: a College of American Pathologists Q-Probes Study of 657 institutions. Arch Pathol Lab Med 1998;122:865-70. 9. Collinson PO, John CM, Gaze DC, Ferrigan LF, Cramp DG. Changes in blood gas samples produced by a pneumatic tube system. J Clin Pathol 2002;55:105-7. 10. Keshgegian A, Bull G. Evaluation of a soft-handling computerized pneumatic tube specimen delivery system. Am J Clin Pathol 1992;97:535-40.
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11. Beveridge R, Clarke B, Janes L, Savage N, Thompson J, Dodd G, et al. Canadian Emergency Department Triage and Acuity Scale (CTAS) Implementation Guidelines. Can J Emerg Med 1999; 1(3 suppl). 12. McClellan E, Nakamura R, Haas W, Moyer D, Kunitake G. Effect of pneumatic tube transport system on the validity of determinations in blood chemistry. Am J Clin Pathol 1964;42: 152-5.
13. Delbruck A, Poschmann H. [On the inf luence of pneumatic post transport on clinical investigation material under different operating conditions]. Z Klin Chem Klin Biochem 1968;6:211-6. 14. Fernandes CMB. Emergency department overcrowding: what is our response to the ‘‘New Normal’’? Acad Emerg Med 2003;10: 1096-7. 15. Altieri M, Camarca M. Point of care testing. Clin Pediatr Emerg Med 2001;2:275-9.
Clarification In the December 2005 and February 2006 issues of JEN, Iris Frank, RN, MSN, was the section editor of the compilations, ‘‘Emergency Response to the Gulf Coast Devastation by Hurricanes Katrina and Rita: Experiences and Impressions.’’ The authors of the Katrina articles were as follows: December 2005;31(6):526 ] 47 Mikki Grit, RN April Wood, RN, EMT Jennifer Crate, RN, CEN Bob McBride, RN Tim Butcher, RN, BSN, EMT-P Sue Connell, RN Curt Audin, RN Kerry Jeanice, RN, EMT-P Robin Page, RN, CEN Bernie Heilicser, DO Mary Connelly, RN, CEN Jo Ann Edwards, RN Knox Andress, RN Sharon Cohen, RN, CNS Karen To’oto’o, RN, BS
February 2006;32(1):56 ] 62 Nancy Chiocchi, RN, MSN Helen Sandkuhl, RN, MSN, CEN, TNS, FAEN Joan Eberhardt, RN, BSN, MA, CCRN, FAEN Virginia Myerscough, RN, BSN, CEN Scott Howard, RN
The editors are grateful to all of the contributors who shared their stories and furthered our understanding of the events that unfolded in the aftermath of Hurricane Katrina.
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