Evaluation of a portable clinical analyzer in the pediatric emergency department: analysis of cost and turnaround time.

ABSTRACT

Background. The objective of this study was to evaluate a portable clinical analyzer (PCA) in the pediatric emergency department (ED), examining (1) turnaround time, (2) cost, and (3) sample amounts for PCA versus standard laboratory.

Methods. Twenty children were studied. Laboratory measurements were taken from the study group using PCA and central laboratory as the control.

Results. The PCA turnaround times were 54.2 minutes faster than the central laboratory. Cost was $1.65 less for the PCA. The PCA sample size was smaller (0.29 mL vs 2.62 mL).

Conclusions. Laboratory values obtained by PCA were available to treating physicians significantly faster than those from the central laboratory. The PCA costs less and uses a smaller blood sample than the central laboratory. Use of PCA technology has the potential to decrease laboratory turnaround time and cost. Further investigation on the influence of patient care is needed.

**********

IN THE PEDIATRIC emergency department, time can be a critical factor in the outcome of patient care. The availability of test results, which may guide emergency treatment, can be delayed by many variables. The hospital laboratory is one area of potential delay. A considerable amount of time can lapse from the time laboratory samples are drawn from the patient until the results are communicated to the treating physician. Researchers have developed point-of-care testing to help address these issues.

Point-of-care testing is defined as any kind of laboratory testing done outside of the central laboratory. (1) Portable clinical analyzers are a recent technologic advancement that have the potential to reduce the turnaround time of laboratory results while maintaining a simplicity that allows their use by nonlaboratory health care professionals. (2,3) The accuracy and precision of these PCAs has been shown to be equivalent to, if not better than currently established laboratory based systems. (2-8) However, the cost of operating a PCA in the acute care setting has not been fully investigated.

Previous studies have not evaluated this technology in the pediatric ED, where it may be most useful. Patients brought to the pediatric ED often do not have sufficient history available. Physicians treating children in this population may rely more heavily on test results to help guide their interventions and diagnoses. This study examined the cost of PCA use and its potential to decrease laboratory turnaround times in a pediatric ED.

MATERIALS AND METHODS

The i-STAT handheld analyzer is used in conjunction with i-STAT cartridges for the simultaneous quantitative determination of specific analytes in whole blood. The handheld analyzer is 6.41 cm wide x 20.97 cm long, and is 5.21 cm deep. The weight is 520 grams. Two 9-volt lithium batteries power the unit. Disposable cartridges house biosensors along with microfluidic components and a calibration solution. The cartridges require a sample volume of 65 [micro]L and have an analysis time of 90 to 140 seconds. Each individually packaged cartridge automatically propels the calibrant solution over the biosensors to perform a 1-point calibration just before the passage of the blood sample over the biosensors. (6) Several cartridge configurations are available (Table 1). We chose the EC 8+ and EC 7+ models because these offered the tests we consider most useful in a pediatric ED setting. (9)

The following protocol was approved by the Institutional Review Board for Human Use at the University of Alabama at Birmingham Hospital. All studies were done at the Children's Hospital, whose research is governed by the University. The study incorporated the pediatric ED population at the Children's Hospital. The annual ED volume is approximately 60,000 patients. This population is composed primarily of minority, inner-city children.

Inclusion criteria were (1) ED patient population, (2) age birth to 16 years, and (3) presenting symptoms or complaints that warranted laboratory studies as part of the ED evaluation. Laboratory studies were limited to those that could be evaluated by both the PCA, and the central laboratory. These measurements included sodium, potassium, chloride, bicarbonate, blood urea nitrogen, pH, PO2, PCO2, total CO2, oxygen saturation, ionized calcium, base excess, anion gap, hemoglobin, hematocrit, glucose, and base deficit.

Diagnoses considered included those that would routinely warrant laboratory investigation of serum electrolytes and/or hematologic values (such as hemoglobin, hematocrit, and blood gas analysis). These diagnoses included but are not limited to diabetic ketoacidosis, dehydration, failure to thrive, altered mental status, seizure, respiratory distress, cardiac arrest, and trauma (Table 2).

The primary outcome variables studied were elapsed time before the laboratory results were available to the treating physician and the cost of PCA use versus central laboratory. Laboratory results for PCA were recorded as they were read from the PCA display screen. Results from the central laboratory were documented as available once they were called to the treating physician or when they were printed on the ED printer. Laboratory computer results are printed in the ED simultaneously as they are recorded in the laboratory.

The cost variable was limited to laboratory cost for each patient. For the PCA group, this is the cost of the cartridge used to analyze the blood sample. Portable clinical analyzer technology allows testing without specialized personnel, thereby limiting additional cost. For the central laboratory group, the cost of the individual test included the cost of the materials and the fee for the technologist's services.

If eligible, informed consent was obtained. The study group had blood drawn and samples run on the PCA and in the standard laboratory as a control. All PCA studies had standard laboratory studies as controls, and no patient care decisions were based on PCA results alone. A power of 80% was used, with a two-tailed [alpha] of .05. Twenty patients provided 40 interventional and control observations that allowed detection of a minimum of 15 minute differences in the "time to results" and 50% differences in mean laboratory costs.

Each patient was entered into True Epistat statistical software for use in this study. Numeric variables indicating laboratory turnaround times in the ED were analyzed using Student's t test for determining differences in population means. All patient data were coded appropriately, preserving patient confidentiality.

RESULTS

Of the 20 patients enrolled in our study (allowing 40 interventional and control observations), 11 were male and 9 were female. The average turnaround time for PCA testing was 2.2 minutes (SD 0.5 minutes). The central laboratory had an average turnaround time of 56.3 minutes (SD 22.2 minutes). The i-STAT required 54.2 minutes less than the central laboratory (t = -10.917, P < .001; 95% CI, -44.12 to -64.25).

The mean cost of the i-STAT group is $9, versus the mean cost of the laboratory group of $10.65. This yielded a difference of $1.65 (95% CI, 0.01 to -3.30, t = 2.02, P = .05). The current cost for the EG [7.sup.+] and EC [8.sup.+] panel tests on the i-STAT are $9 per cartridge (Table 1), which is similar to the cost of the individual tests included in this study ($9.96 for a blood gas analysis with electrolytes and $9.15 for a fluid balance panel with 8 values, including laboratory technician expense). The cost of PCA is much lower, however, considering that there are elements- of both the blood gas and fluid balance panel on the EC [8.sup.+] and EG [7.sup.+] cartridges (Table 1).

For PCA testing, the blood sample averaged 0.29 mL. The standard laboratory amount averaged 2.62 mL (though the minimal amount required by the laboratory is 0.5 mL). Therefore, the i-STAT uses 2.31 mL less than the central laboratory (t = -7.196, P < .001; 95% CI, -1.66 to -2.96).

DISCUSSION

The concept of point-of-care testing represents a fundamental shift in diagnostic testing, the objective being cost-effective, patient-focused testing at the site of diagnosis and management. (6) The PCA is an evolving technology intended to address these issues. Previous studies have validated the analytical accuracy and precision of these devices and their reliability in the hands of nontraditionally trained health care professionals. (2-6) However, the cost of operating a PCA versus using a central laboratory has not been extensively detailed. The debate continues about the ideal setting for these devices. (4,8,10,11) We believe that the rapid turnaround times of the PCA combined with the minimal blood sample size make the pediatric emergency and acute care setting ideal for implementing this technology.

In this study from a pediatric ED, PCA results were available significantly faster than results from the central hospital laboratory. Test results may facilitate medical decisions that guide emergency interventions despite little or no knowledge of the patient's medical history. This is especially important when dealing with the acutely ill or injured child. Time is a critical element in the outcome of these patients, and efforts that can reduce decision-making times on any level may prove significant.

Rapid availability of test results, within minutes of phlebotomy, may result in faster decision-making and earlier intervention. This could further avoid unnecessary diagnostic tests, establishing earlier diagnoses, and shortening patient time in the ED. These contributions have potential to affect patient flow in the ED at all levels, not just the individual patient. If the time to a patient's admission or discharge from the ED can be reduced, then subsequent patients can be seen more rapidly. This can potentially decrease waiting room times and improve patient care and satisfaction on many levels. Further studies are needed to evaluate these potential benefits.

In this study, physicians did not use PCA results in their medical decision-making without having laboratory values confirmed by the central laboratory. In several instances, however, unexpected or useful clinical findings were observed when using the i-STAT technology. These included diagnosis of diabetic ketoacidosis, as well as findings of abnormal electrolyte values in patients with alterations in mental status, leading to more rapid detection and treatment. We also noticed on several occasions the benefit of the small blood sample needed for use of the PCA. On several occasions, intravenous (IV) access or blood samples could not be obtained rapidly because of the patient's condition or hydration status. Our experience showed that small amounts of blood from a failed IV access attempt or "blown vein" were sufficient for PCA studies. Results were often available to the treating physician before samples for the central laboratory were collected.

Patients who require serial laboratory analyses, such as patients with trauma, diabetic ketoacidosis, or severe dehydration, benefit not only from the efficiency of the i-STAT and reduced patient discomfort, but also from the minimal blood sample volume required for analyses. In critically ill patients and the very young, drawing large amounts of blood can exacerbate already life-threatening conditions. Also, the PCA cartridges are a closed system, and caretakers benefit from minimal exposure to the blood sample.

With rising health care costs and declining reimbursements, focus on cost vs benefit issues remains at the forefront of medical decision making. In this study, the cost of performing i-STAT analysis was $9 per patient, an average of $1.65 less than the central laboratory. The study group of 20 patients is a small sample for comparing these laboratory costs. The number of tests ordered varies from day to day and with the time of year. To address this, a cost analysis of i-STAT versus our central laboratory for 20 and 40 tests a day is presented in Table 3. The cost of implementing the technology is also relatively inexpensive. The i-STAT analyzer costs approximately $6,000, and specific cartridges are purchased according to need.

The PCA also has many cost containment variables that are not as easily measured. As in this study, the user friendly PCA eliminates the need for specialized personnel. The small blood volume required can bypass the need for venipuncture and subsequently the time, equipment, and specialized personnel associated with that skill. The PCA also eliminates the need for specimen transport.

The study was limited to a single ED setting. Laboratory efficiency varies from institution to institution. The study is not generalized to the entire ED population, since only certain diagnoses were considered eligible in our study. The sample size of 20 patients with respect to comparing laboratory costs is a small sample size.

CONCLUSION

We found that the PCA offered an efficient alternative to the central laboratory in a select patient population. The technology allows easy maintenance and calibration. The small specimen sizes and the rapid turnaround times have the potential for significant clinical impact on the patients in the pediatric ED, where immediate access to laboratory results is required for urgent clinical decision-making. The potential to guide therapeutic care in a cost effective way in the ED course needs further evaluation. The potential not only for earlier interventions, but also for earlier patient discharges or disposition needs further evaluation.

TABLE 1. Available Cartridge Configurations for the i-STAT Portable
Clinical Analyzer

i-STAT EC 8 *             i-STAT EG 7 *

Sodium                    Sodium
Potassium                 Potassium
Chloride                  Ionized calcium
pH                        Hematocrit
P[CO.sub.2]               pH
Blood urea nitrogen/urea  P[CO.sub.2]
Glucose                   P[O.sub.2]
Hematocrit                Total [CO.sub.2] *
Total [CO.sub.2] *        HCO3 *
HCO3 *                    [BE.sub.ccf] *
[BE.sub.ccf] *            Oxygen saturation *
Hemoglobin *              Hemoglobin *

* = When cartridges have sensors for both pH and P[CO.sub.2] bica
(HCO3), total carbon dioxide Total [CO.sub.2]) and base excess can be
calculated.
TABLE 2. Comparison of a Portable Clinical Analyzer (i-STAT) and
Standard Laboratory Hemotologic Studies

                                Blood Sample  Time for Results
                                    (mL)            (min)
Patient  Diagnosis              i-STAT   Lab    i-STAT    Lab

 1       Diabetic ketoacidosis   0.1      1       2        40
 2       Seizure                 0.3      4       2        45
 3       Seizure                 0.1      3       2       120
 4       CHD                     0.1      3       2
 5       Altered mental status   0.3      6       2        46
 6       Altered mental status   0.2      3       2        45
 7       Altered mental status   0.1      1.5     2        49
 8       Dehydration             0.3      3       2        25
 9       Vomiting                0.3      0.5     2        35
10       Seizure                 0.5      3       2        53
11       Dehydration             0.5      2       3        65
12       Diabetic ketoacidosis   1.0      3       2        75
13       Dehydration             0.5      2       3        80
14       Vomiting                0.25     1       2        43
15       Diabetic ketoacidosis   0.8      1.5     2        57
16       Vomiting                0.4      2       2        80
17       R/o sepsis              0.1      1       2        57
18       CHD                     0.1      3       2        32
19       Lethargy                0.08     5       2        55
20       Altered mental status   0.3      4       3        58

                 Cost
                  $
Patient  i-STAT        Lab

 1         9.00  19.11 ABG + FBP
 2         9.00   9.15 FBP
 3         9.00   9.15 FBP
 4         9,00   9.15 FBP
 5         9.00   9.15 FBP
 6         9.00   9.15 FBP
 7         9.00   9.15 FBP
 8         9.00   9.15 FBP
 9         9.00   9.15 FBP
10         9.00   9.15 FBP
11         9.00   9.15 FBP
12         9.00  19.11 ABG + FBP
13         9.00   9.15 FBP
14         9.00   9.15 FBP
15         9.00  19.11 ABG + FBP
16         9.00   9.15 FBP
17         9.00   9.15 FBP
18         9.00   9.15 FBP
19         9.00   9.15 FBP
20         9.00   9.15 FBP

ABG = Arterial blood gas analysis, FBP = fluid balance panel, CHD =
congenital heart disease, R/o = rule out.
TABLE 3. Cost Analysis for Testing With a Portable Clinical Analyzer
(PCA)

                                       Blood Gas     Fluid Balance
                              PCA    Analysis (BGA)   Panel (FBP)
                            ($9.00)     ($9.96)         ($9.15)

Assuming 20 tests each day  $180.00     $199.20         $183.00
Assuming 40 tests each day  $360.00     $398.40         $366.00

                                       Potential Annual
                            BGA + FBP   Cost Savings--
                            ($19.11)      BGA + FBP

Assuming 20 tests each day   $382.20      $73,803.00
Assuming 40 tests each day   $764.40     $147,606.00

Acknowledgment. We thank Regenia Williams who helped with data collection.

References

(1.) Santrach PJ, Burritt MF: Point-of-care testing. Mayo Clin Proc 1995; 119:493-494

(2.) Jacobs E, Vadasdi E, Sarkozi L, et al: Analytical evaluation of i-STAT portable clinical analyzer and use by non-laboratory health care professionals. Clin Chem 1993; 39:1069-1074

(3.) Herr D, Newton M, Santrach P, et al: Airborne and rescue point of care testing. Am J Clin Pathol 1995; 104(suppl 1):s54-s58

(4.) Woo J, McCabe JB, Chauncey D, et al: The evaluation of a portable clinical analyzer in the ED. Am J Chin Pathol 1993;10:599-605

(5.) Rosenbaum J, Watson D, Perkins S: Evaluation of the I-STAT analyzer in a neonatal intensive care unit. Arch Pathol Lab Med 1991; 119:969

(6.) Mock T, Morrison D, Yascoff R: Evaluation of the i-STAT system: a portable chemistry analyzer for the measurement of sodium, potassium, chloride, urea, glucose and hematocrit. Clin Biochem 1995; 28:187-192

(7.) Salem M, Chernow B, Burke R, et al: Bedside diagnostic blood testing: its accuracy, rapidity, and utility in blood conservation. JAMA 1991; 266:382-389

(8.) Meirav M, Yehezkel W: Point of care testing: a critical review. Pediatr Emerg Care 2000; 16:45-48

(9.) i-STAT Systems Manual 151530 Revision H. Princeton, NJ, i-STAT Corp, 1998

(10.) Lamb S: Responsibilities in point of care testing: an institutional perspective. Arch Pathol Lab Med 1995; 119:886-889

(11.) Belanger A: Alternate site testing: the regulatory perspective. Arch Pathol Lab Med 1995; 119:902-906

RELATED ARTICLE: KEY POINTS

* Laboratory values obtained by the portable clinical analyzer (PCA) were available to treating physicians significantly faster than those from the central laboratory.

* The PCA costs less and used a smaller blood sample than the central laboratory.

* Use of PCA testing has the potential to decrease laboratory turnaround time and to decrease cost.

From the Department of Pediatric Emergency Medicine, Children's Hospital of Alabama, University of Alabama at Birmingham.

Equipment for this study was provided by the i-STAT Corp, 303 College Rd E, Princeton, NJ 08540.

The authors have no commercial or proprietary interest in the i-STAT device. The Critical Care Transport team at the testing institution uses i-STAT technology, but there is no financial interest in or obligation to the i-STAT Corp.

Reprint requests to Byron Mainor, MD, Children's Acute Care, 524 Beaumont Rd, Fayetteville, NC 28304.