Co-creating critical limits for enhanced acute care: proven need and web knowledge base Part 2: Standard of care, what it means and how it is applied

Dec. 19, 2015

Editor’s note: A few months ago, I sent Dr. Kost, who serves as the reviewer of the Table of Critical Limits that appears in MLO’s annual publication Clinical Laboratory Reference (CLR), a question from a reader, in the hopes that he would respond to it for MLO’s recurring “Tips from the Clinical Experts” column. The question was this: “What are critical values for routine coagulation testing (i.e., PT and PTT) for therapeutic and diagnostic testing?”
Dr. Kost responded with a discussion of a scope far beyond that of typical “Tips” answers: A two-part discussion—and call to action—on the broader topic of standardized critical limits for enhanced acute care. I enthusiastically took Dr. Kost up on his offer to address this important topic for MLO once again, as he did for the magazine with a colleague more than 20 years ago. MLO ran Part 1 in the December 2015 issue, and is pleased to present Part 2 in this January 2016 issue.

In Part I in the December 2015 issue of MLO, I focused primarily on coagulation critical limits and showed that we could use the web productively. Now I move on to discuss some important legal aspects of the definition and application of critical limits. These legal aspects apply broadly. They are not limited to any one category of analytes.

The fundamental concept of standard of care is based on the legal case, Vaughan vs. Menlove, 3 Bing NC 468, 132 ER 490 (CP 1837), wherein the judge instructed the jury to reason whether the defendant “proceed[ed] with such reasonable caution as a prudent man would have exercised under such circumstances.” In simple terms, it is the level at which the average, prudent provider in a given community would practice and how similarly qualified practitioners would have managed the patient’s care under the same or similar circumstances.

When under oath, whether during a deposition or in a court of law, including arbitration proceedings, one must be able to recite this definition of the standard of care and explain whether or not the medical actions being challenged met the standard of care viewed generally from the national or sometimes regional perspective—not local. Hence, for laboratory practitioners and now point-of-care (POC) coordinators, access to web-based survey results can be extremely valuable. Additionally, one should not wait for a crisis (e.g., huge financial loss) to hit, but instead proactively mitigate risk.

Legal Principles. The easiest way to appreciate the legal principles that unfold when there is an adverse outcome related to critical limits is to consider that you, the reader, could be called to task and required to explain during deposition or to a jury: a) each and every detail of your critical values policy and each entry on your critical limit list; b) the rationale and consensus process by which you selected them; and c) the manner in which they were originally derived, implemented, updated, changed, and practiced in your hospital setting or in point-of-contact areas. The last could include even primary care sites and homes in the community of patients who self-test.

Application. Specifically, you will be interrogated intensively regarding the selection process and, under cross-examination, must explain any and all variances from published national survey critical limits deemed admissible for comparison by the court. Usually, admissibility means you can use the data you find online in the MLO CLR (Clinical Laboratory Reference) tables, in the publications cited herein, or in other pertinent factual sources revealed during discovery by either side.

Sometimes attorneys will refer to the mean as indicative of the standard of care, and at other times, the median, so a basic appreciation of the differences in parametric versus non-parametric statistics is helpful. All levels of personnel can be subjected to these legal interrogations—the clinical laboratory professional, nurse, laboratory director, IQCP planner, physician, administrator, information technology staff, and others. You might find yourself on the stand in court, so it is important to understand the court’s viewpoint!

How surveys are treated by attorneys and courts

Attorneys and the courts are interested in establishing the standard of care and whether it was breached in a particular case. In some instances, a court has thrown out critical values publications based on surveys of professional members/subscribers, because the data were deemed “heresy,” defined as member/subscriber opinions potentially at variance and not reflecting the broad national standard of care. On the other hand, legal authorities accept results based on objectively defined and statistically sampled surveys with an adequate response rate, typically in the order of 70 percent (e.g., references 1-3 at the end of this article).

Various professionals with proven credentials, typically demonstrated by published track records in critical values innovation, research, and practice, are called upon as expert witnesses in litigated controversies involving inappropriate selection of quantitative critical limits or qualitative critical values, failure to follow hospital written policies, lack of timely notification of critical results, instrument measurement errors leading to missed critical test result findings, and other factors, such as results overlooked at the point of care, that may be considered medical malpractice.

The impact of legal outcomes

Settlements, which depend on both adverse outcomes and their causality, such as the death of an adult from a missed critical cardiac biomarker result in the clinical laboratory or at the point of care, or the lifelong disastrous mental impairment of an infant from kernicterus following an overlooked elevated bilirubin level not treated promptly with phototherapy, can be in the range of millions of dollars.

Patient harm and the dysfunctional consequences of sloppy communication practices motivated The Joint Commission (TJC) to integrate urgency rules for critical results notifications in the National Patient Safety Goals (NPSGs) several years ago. These derisking measures currently appear in the 2015 NPSGs. The reader can find the NPSGs online.4

However, TJC offers no precise guidance for selecting critical limits nor justifying them medically. That part is up to the individual hospital team, and in this article, we are positing that the time has come for hospitals everywhere in America to share their critical values experience in the web-public domain in order to improve collective practice and the standard of care in this area.

Public domain listings—mostly pros and hardly cons

What has not happened, and should, is proactive action by hospitals and their laboratory professionals to make critical values lists and policies freely and easily available for harmonization, while at the same time mitigating risk from inconsistent practices, clumsy thresholds, or just plain confusion, such as our current survey found for PTT and aPTT. This article calls to action transparency, consistency, cost-effectiveness, and ultimately, harmonization. Further, this approach is not based on guidelines written from professional opinions, the lowest form of evidence, but instead on actual critical limits used every day in American hospitals—that is, raw data.

Note that since the publication of the JAMA and Pediatrics papers about 25 years ago,1,2 we have not observed a single situation in which attorneys have been unable to produce lists and policies, no matter how well cloistered, from individual hospitals during the discovery phase of litigation and then present them as evidence for or against the legal action, as the case might be. I have seen six-foot tall poster boards of critical limits lists presented to juries, and unbeknownst, even from my own institution!

Therefore, especially now in the current e-world there is nowhere to hide, and hospitals have little to be concerned about in regard to proactively making critical limits lists public and much to gain if they do so. National practices will become transparent, including inadvertent outliers, omitted analytes deemed essential, forgotten points of care, deficiencies in identifying age-related limits, confused therapeutic constraints, or simply listing too many analytes and reducing impact.

Establishing a public domain knowledge base using the web

Individual hospitals, clinics, and primary care sites should first originate or confirm frequently critical values based on their own consensus process among laboratory, clinical, and other stakeholders. Operators and patients performing testing at points of need also need guidance. In fact, this study may be the first web-based documentation of an INR of 5.0 as a reasonable critical limit for the standard of care in coagulation. Besides being well confirmed by other studies, its novelty lies in proving the feasibility of using the web as a suitable media in the worldwide call to action (In this regard, the reader might return to the sidebar in Part 1, MLO 47(12):36.)

Therefore, it is recommended that all hospitals publish their list(s) of critical limit list(s) and associated policy(ies) on the web, in order to co-create an actionable public domain knowledge base with unburdened free access for practitioners, researchers, point-of-care coordinators, patients, and even attorneys.

Care must be taken to assure that point-of-care results, wherever and by whomever they are produced along patient spatial care paths (SCP),5 starting in the home and possibly telecommunicated to the clinical team, follow the same uniform practice standard of care, including rapid bidirectional notifications and clear documentation of how long it takes for the decision maker to receive critical test results and take appropriate action.

Conclusions and recommendations

  • The selection and design of critical limits, qualitative critical values, and attendant policies should be evidence-based. The WorldWide Web presents collective groups of medical professionals with a unique opportunity to proactively contribute to a publicly shared knowledge base by posting their hospital documents and then extracting from the web “colligative” properties that harmonize the practice of urgent critical test result notifications.
  • The key is  getting adequate numbers of postings on the web and achieving fairly even geographic representation of states throughout the nation and of countries globally, so that researchers can sample from various sets of raw data without bias error-free, and also be assured of an immediately adequate response rate, which is more or less automatic if access is freely available and enough primary documents are available. Indeed, the primary documents should be collected, that is, extracted from websites, to avoid transcription errors and flaws resulting from truncation as described above.
  • With such a knowledge base resource, we will be able to answer important questions, such as whether there has been “drift” in quantitative critical limits since the first national surveys were conducted 25 years ago, why so many critical values are now listed, whether they are necessary, and which critical values reflect the “core” essential ones for patient survival.
  • Additional questions include, but are not limited to, the following: Has that core been altered by the implementation of POCT? Can practice be more impactful for outcomes? How can inconsistencies be eliminated to restore original purpose, treating life-threatening conditions immediately upon their detection? This call to action for a freely shared web knowledge base and global harmonization seeks and suggests the means to facilitate high quality patient-focused decision making at the speed of life.


The results presented in this article are preliminary, subject to change upon gathering of more data during this new e-round of national surveys, and likewise, interpretations are tentative. The small sample for POCT may not be representative of the larger population who use POC critical limits, and here, only INR is reported, while actually other POC instrument analytes, such as glucose, potassium, and troponin I, were posted in the lists we gathered online—so beware this new facet of the standard of care!


  1. Kost GJ. Critical limits for urgent clinician notification at US medical
    centers. Journal of the American Medical Association. 1990;263:704-707.
  2. Kost GJ. Critical limits for emergency clinician notification at United States children’s hospitals. Pediatrics. 1991;88:597-603.
  3. Kost, G.J. The significance of ionized calcium in cardiac and critical care:  Availability and critical limits at US medical centers and children’s hospitals. Archives of Pathology and Laboratory Medicine. 1993;117:890-896.
  4. The Joint Commission. National Patient Safety Goals Effective January 1, 2015. [Accessed September 20, 2015.]
  5. Kost GJ, Ferguson, Kost LE. Principles of point of care culture, the spatial care path, and enabling community and global resilience. Journal of the International Federation of Clinical Chemistry. 2014;25:4-23.
Gerald J. Kost, MD, PhD, MS, FACB, serves as Founding Director of the Point-of-Care Testing Center for Teaching and Research (POCT•CTR) and as Emeritus Faculty in the School of Medicine, UC Davis. He is also founder of Knowledge Optimization in Davis, CA.