The evolving needs of critical care.
Critical care is one of the most diverse and rapidly expanding disciplines in medicine. The specialty has been revolutionized by recent technologic advances, from transesophageal echocardiography to ventricular assist devices and extracorporeal membrane oxygenation. A new crop of monitoring techniques allows continuous analysis of respiratory and hemodynamic functions.|1-3~ ECG and blood pressure monitoring have been coupled with more sophisticated devices that provide comprehensive analysis of parameters such as mixed venous |O.sub.2~ saturation and coronary sinus blood gases.|4-6~
* Caseload challenge. The technology boom, combined with an ever-wider therapeutic armamentarium, arrived just in time to help intensivists cope with a daunting change in the patient population. The ICU patient of today is likely to be older and sicker than the ICU patient of the past. Furthermore, the ICU is treating more patients with acute multisystem failure and a multiplicity of chronic diseases.|7,8~ Even in specialized ICUs, such as coronary care units, it is increasingly rare to find a critically ill patient with only the disease process for which that unit has been designated. We face daily and hourly decisions concerning which problem to treat at any given time.
Critical care management assumes new dimensions in the presence of comorbidity. The challenge is even greater when an advanced disease process is present, such as diabetes, end-stage hypertension, cardiomyopathy, immunodeficiency syndrome, or adult respiratory distress syndrome (ARDS). The ICU is further burdened by advanced surgical procedures requiring longer recovery time than surgeries of the past. Three examples are transplantation of the pancreas, heart, and liver. Even "garden-variety" surgeries such as cholecystectomy and pacemaker insertion demand more complex postoperative care when performed on older or more fragile patients, as is increasingly the case. An additional source of pressure is the declining ratio of physicians to patients in many critical care units.
* Team versus time. By necessity, the ICU has evolved into a multidisciplinary arena. The critical care team coordinates all aspects of patient care. The composition of this team, which varies among institutions, may include representatives of the departments of medicine, surgery, anesthesiology, nursing, pulmonology, physical therapy, laboratory, radiology, pharmacy, or social services. Unless these teammates and their departments cooperate fully, overall efforts to improve patient care will be futile.|9~
In the ICU, the only constant is rapid change. No area of patient care, except perhaps the emergency room, is more dynamic. Adapting to sudden and critical fluctuations in patient status requires frequent and complicated interventions. Having hemodynamic, clinical, and laboratory data available on demand is vital.
When a situation requiring treatment arises, all pertinent information is needed as quickly as possible. It is helpful that certain parameters, including heart rate, blood pressure, oxygen saturation, pulmonary artery pressure, central venous pressure, and mixed venous oxygen saturation, can be continuously monitored. Despite the wealth of hemodynamic information provided by these monitoring devices, it is not enough.
Patience is not always a virtue in critical care. In some ICU situations, any wait for a test result--even a "short" one--delays important therapeutic response. High on the ICU wish list is point-of-care technology offering rapid (or, ideally, continuous or instantaneous) feedback of metabolic functions such as blood gases, electrolytes, chemistries, and hematocrit, without compromising accuracy or reproducibility. To succeed, such a system must address the needs of both physicians and nurses.
* Nurse's-eye view. From a nursing perspective, what aspects of point-of-care technology would most enhance diagnosis and treatment of the critically ill patient? A system or device that cuts down on paperwork. walking around, and other nonclinical chores will free the ICU nurse to spend more time attending to patients' physical and emotional needs. Patient-controlled analgesia is one success story, improving quality of care while reducing the time nurses spend delivering and administering medication.
Drawing and labeling blood specimens, transporting them to the central laboratory, and retrieving the results consumes precious time for nurses and other ICU staff members--time away from the bedside of a patient who may need medication titrated, blood replaced, or ventilation adjusted. By eliminating the need to collect and send specimens and gather results, point-of-care technology has the potential to streamline patient management and boost nursing efficiency. Not least of its attributes would be its ability ultimately to reduce the overall cost associated with each test request.
* Physician's perspective. The ICU was never a leisurely place to work, but the factors cited above have made things even worse. Often, it seems the physician must be at two or more bedsides at once, managing simultaneous crises. Under these conditions, it is impossible to provide appropriate therapeutic intervention without up-to-the-minute laboratory information. Unfortunately, obtaining much of that information involves a delay that, however brief, may still be too long. For the critical care physician, the major issue related to monitoring and testing is response time.
* Drug management. Drug therapy calls for swift and precise adjustment to many parameters. The countless agents at our disposal are often used in exacting regimens that may combine a vasopressor with a vasodilator or other disparate drugs. When should a dosage be changed or an agent added or withdrawn? Only pharmacologic fine-tuning will maximize effectiveness while minimizing side effects and adverse interactions. The patient's biochemical and hemodynamic status must be identified whenever necessary.
* Surgical frontiers. The growing diversity of surgical procedures, both elective and emergent, and the increasing acuity of underlying disease states in surgical candidates have raised the stakes for test turnaround time in the surgical ICU.
* Mechanical assist devices. Supportive technologies are often used as a bridge to transplantation in extremely ill patients experiencing suspected failure of multiple organ systems. These measures include right and left ventricular assist devices, intra-aortic balloon counterpulsation, and pulmonary artery counterpulsation. Most patients in this situation require anticoagulation and hematologic monitoring as well as close hemodynamic monitoring. The left ventricular assist devices currently in use at our institution can provide intermittent hematologic monitoring at the bedside.
* Multiple draws. Repeated blood draws for lab determinations are costly and labor-intensive. They also subject critically ill patients to blood draws as often as once an hour, thus potentially compromising their hematologic and hemodynamic status.
* Reimbursement pressures. No clinician wants patients to spend unnecessary days in the ICU, nor can most hospitals afford it. Having clinical data promptly helps physicians order patients' removal from the unit at the first appropriate opportunity or provides evidence that they are not ready to leave.
* Information overload. Sorting through an avalanche of data in search of the most important value of the moment can be a formidable task for the clinician. To relieve this problem, reporting systems must provide test results when and where needed and should be designed to make all available data easy to use. In the ICU at our institution, a bedside computer for each patient provides instant access to the information systems of both the laboratory and the hospital. This state-of-the-art arrangement will probably be routine in tertiary care centers before the end of this decade.
* Assigning priorities. Many ICU test request forms, including those used at our institution, are preprinted Stat. The inevitable result is Stat abuse. The routine 4 a.m. blood specimen become indistinguishable in terms of urgency from the badly needed potassium level for a patient experiencing dysrhythmias. Frustration for both clinician and laboratory is the predictable response.
To differentiate test orders that truly deserve the name of Star from those that do not, direct providers of health care in the critical care setting must work with indirect providers in the central laboratory to define the conditions that constitute unequivocal medical emergencies. Some of the questions it is helpful to ask in determining these criteria are listed in "Identifying 'real' Stats." found in a box on the preceding page.
* Partial solution. Obtaining more efficient systems for conventional laboratory requisitions will help limit the testing workload generated by the intensive care unit, but they won't be enough. We need inventive solutions for point-of-care testing in the ICU and elsewhere. The technology for measuring biochemical parameters using whole blood at the bedside is already here, and it certainly has the potential to solve the problem of turnaround time. It also raises important questions, however, about accuracy, accountability, and cost.
Economic issues have penetrated to the foreground of health care considerations. Which departments should install point-of-care technology? Will its use be reimbursable to patients? Will testing revenues shift from one department to another?
Even more important than cost is the ultimate impact on quality of care. Who will perform bedside analyses? Who will assure their accuracy?
Nurses are often the first candidates mentioned for the job. Yet the ICU nurse is already inundated by duties involving direct patient care. More important, performance of clinical tests by nonlaboratory personnel may make results less valid.
There is far more to clinical laboratory testing than collecting a specimen and pushing a button. Qualified personnel must be responsible for instrument calibration, maintenance, and troubleshooting as well as for data recording and documentation and for quality control. When testing is moved out of the central laboratory, accountability for these functions can become a logistical and even a political hurdle. While no easy solutions come to mind, there is one clear path to success: cooperation, with the quality of patient care seen as the overriding consideration.
Never has the collaborative relationship between the staffs of the laboratory and the critical care unit been more important. Each institution will have to insure efficiency and accuracy of point-of-care testing in its own way; the sprawling university medical center will require a different system from the compact community hospital. In all cases, the common denominator will be open communication.
* Opportunity knocks. Clinical laboratorians often feel threatened professionally and financially in contemplating the expansion of point-of-care testing. Without the central laboratory's full support, however, such initiatives cannot succeed. Point-of-care testing represents more than faster test results in the ICU. It also provides the laboratory with opportunities to extend and diversify the talents of its clinical and managerial staff.
To include the central laboratory in early stages of planning, a pathology resident or laboratory supervisor might be asked to help develop policies and procedures for lab oversight of point-of-care testing devices. To go forward with point-of-care testing without actively soliciting the advice and participation of the resident testing experts, laboratorians, would be counterproductive.
Implemented wisely, point-of-care testing should make the central laboratory more efficient and productive. An ICU with the capacity to perform routine blood gas measurements or chemistries, for example, would relieve the central laboratory during workload peaks to concentrate on genuine Stat orders or on tests requiring more sophisticated analysis than what was available at the bedside.
Critical care medicine has been hurtled into a technologic growth spurt. The most positive aspect of this metamorphosis is continued improvement of patient care. We now have unprecedented capabilities to sustain and prolong life. We are on the job around the clock; and our testing needs grow each day. Performing tests as before will soon pass from inconvenient to impossible. For intensive care to move into the future creatively, it must hold among its resources advanced diagnostic technology at the point of patient care.
1. Surratt, P.M., and Owens, O. A pulse method of measuring respiratory system compliance on ventilated patients. Chest 80: 34-38, 1981
2. Severinghaus, J.W. Historical development of oxygenation monitoring. In: Payne J.B., and Severinghaus, J.W., eds. "Pulse Oximetry," chap. 3. New York, Springer-Verlag, 1986.
3. Arai, T.; Hatano, Y.; Ramatsu, K.; et al. Real time analysis of the change in arterial oxygen tension during endotracheal suction with a fiberoptic bronchoscope. Crit. Care Med. 13: 855-858, 1985.
4. Ellis, D.M. Interpretation of beat to beat blood pressure values in the presence of ventilatory changes. J. Clin. Monit. 1:65-70, 1985
5. Kurki, T.; Smith, N.T.; Head, N.: et al. Noninvasive continuous blood pressure measurement from the finger: Optimal measurement conditions and factors affecting reliability. J. Clin. Monit. 3:6-13, 1987.
6. Griffin, R.M., and Kaplan, J.A. Comparison of ECG leads |V.sub.5~, C|V.sub.5~, C|B.sub.5~ and II by computerized ST segment analysis. Anesth. Analg. 65:S65, 1986.
7. Swan, H.J., and Ganz, W. Measurement of right atrial and pulmonary arterial pressures and cardiac output: Clinical application of hemodynamic monitoring. Adv. Inten. Med. 27:453-473, 1982.
8. Thys, D.M.; Hillel, L.; Goldman, M.; et al. A comparison of hemodynamic indices derived by invasive monitoring and by two-dimensional electrocardiography. Anesthesiology 67:630-634, 1987.
9. Sazama, K., and Haugh, M.G. "STAT: The laboratory's role." Chicago, American Society of Clinical Pathologists, 1986.
Identifying 'real' Stats
When every test request from the critical care unit is labeled Star, the laboratory lacks guidance in assigning priorities. Every health care institution must write its own criteria for emergency test orders. Doing so requires a joint effort by the medical, nursing, laboratory, and administrative departments. Once Star testing has been defined, emergencies can be handled to everyone's satisfaction. When misunderstandings arise, keeping the patient's welfare foremost should help put matters in perspective.
For an effective system, the medical and laboratory staff must work out mutually acceptable answers to these questions:
1. What medical conditions constitute emergencies or potential emergencies?
2. Which laboratory tests should be available Star at all times?
3. How can the laboratorian reliably assign a priority to any single test request or set of requests?
4. What procedures are appropriate for ordering, transporting, and receiving specimens and results?
5. How can the clinician be assured of receiving accurate and timely test results?
6. How can the physician and the laboratorian transmit information with the greatest possible ease and accuracy?
Dr. Hines is associate professor of anesthesiology, Yale University School of Medicine, and director of the cardiothoracic intensive care unit at Yale-New Haven (Conn.) Hospital. Mylott is an intensive care nurse at Yale-New Haven Hospital. Dr. Barash is professor and chairman, department of anesthesiology, Yale University School of Medicine and Yale-New Haven Hospital.
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|Title Annotation:||MLO Special Issue: Point-of-Care Testing|
|Author:||Hines, Roberta; Mylott, Laura; Barash, Paul G.|
|Publication:||Medical Laboratory Observer|
|Date:||Sep 1, 1991|
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