Diagnosing critical conditions like major strokes or serious concussions with precision and ease – using modern highly reliable noninvasive methods – is the norm at UT Southwestern. Any doctor would embrace a painless, accurate, and timely approach, especially in emergency situations. However, despite the proven efficacy of pupillometry, many medical professionals still rely on an unreliable method of using flashlights to assess pupils, a practice that has persisted for decades.
Using a flashlight to assess brain health, though a traditional method, has significant shortcomings. Different types of flashlights are used, some with strong batteries, others with weak ones, leading to inconsistent light intensity. One study revealed that when two providers examine a patient’s pupils with flashlights, they can arrive at completely different conclusions. One might observe no reaction to light, while the other might see a positive response.
UT Southwestern’s Neurocritical Care unit is part of the O’Donnell Brain Institute and has been engaged in research exploring the utility of handheld pupillometry in critical care since 2015, using the Establishing Normative Data for Pupillometer Assessments in Neuroscience Intensive Care (END-PANIC) registry of prospectively collected pupillometer readings from patients admitted to neurocritical care units with a variety of conditions. The findings have revolutionized how the group assesses brain health and determines the best care for the patient.
DaiWai Olson, Ph.D., R.N., Professor of Neurology and Neurological Surgery at UTSW, explains the technology: “Pupillometry is a way of quantifying the pupillary response using a standardized light source, which is at a fixed distance from the eye. It has transformed patient care in the Neuro ICU, and we’ve built a phenomenal infrastructure for clinical research on the topic, publishing an average of about 40 multidisciplinary manuscripts a year to drive the clinical science and prompt widespread adoption.”
“Patients are admitted to the Neurological Intensive Care Unit with a variety of conditions, and there were so many research and clinical questions that we thought of early on that having a large database to sample from would help us evaluate the value of the device,” adds Venkatesh Aiyagari, M.D., Chief of the Division of Neurocritical Care at UT Southwestern and Medical Director of the Neuroscience Intensive Care Unit (Neuro ICU) at William P. Clements Jr. University Hospital.
Today, this ongoing registry houses data from more than 9,000 subjects who have been admitted to four hospitals in the U.S. – three academic medical centers and one community hospital – and one hospital in Germany and one in Japan. The registry currently has nearly 1 million pupillometer readings across various neurological conditions. Exploratory analysis of this database has led to several major publications in the last five years and enabled groundbreaking research into the use of pupillometry as a triage tool for traumatic brain injury (TBI) and as an early indicator of brain tissue shifts in various neurological emergencies. For neurocritical care patients, the results have been extraordinary, with a 300-fold improvement in accuracy, precision, and reliability.
The findings are significant:
Flashlight unreliability: A heavily cited paper demonstrated that using a flashlight to assess pupils is so unreliable that it should be replaced by better tools such as automated pupillometers. This finding is expected to change current practice, potentially eliminating the use of flashlights in pupil assessments within the next 10-20 years.
Objective measurement of pupil size: Objective measurement of pupil size, as opposed to using a flashlight, allows for accurate tracking of changes over time. This precise measurement can identify issues even when pupils appear normal but differ slightly in size, providing valuable insights into pupil function and health.
Holistic assessment: In critical care, accuracy in information is crucial, and leveraging assessment tools such as pupillometry enhances the overall evaluation of patients.
Midline shift detection: Pupillometry can predict worsening midline shifts in patients with large strokes, correlating changes in pupillometry values with the degree of midline shift. This method offers an alternative to frequent CT scans, reducing radiation exposure and costs while being less cumbersome.
Monitoring brain conditions: Pupillometers can monitor for brain swelling in stroke patients, determine the need for intracranial pressure monitors after head injuries, and help identify vasospasm in patients with head bleeding. This tool provides a lower cost, more accessible, and efficient method for assessing and managing brain conditions compared with traditional imaging techniques.
The UT Southwestern team has incorporated these findings into practice and taken this research one step further by automating pupillometer data entry into the electronic medical record to ensure the accuracy and reliability of the data collected and stored. Years ago, nurses would manually enter pupillometry readings, which added a lot of time and the possibility of error.
“We have started automatic data entries with a small device that’s like a small tablet that automatically transmits data to the patient’s chart,” Dr. Olson adds. “The reliability of the data entry is now 100% accurate and delivered in real time.”
Clements University Hospital is the first hospital in the world to ensure that all of the Neuro ICU beds are equipped with an interface that automatically transfers pupillometer data. This allows for the creation of models to assess various pupillometer values, such as changes in constriction velocity during dilation and variations in latency. By analyzing these data clusters, specific signals can be identified, providing valuable insights into patient conditions. The integration of this system enhances the accuracy and efficiency of patient monitoring in the ICU.
The future of pupillometry in medical practice is a game changer, particularly in emergency triage, where rapid and accurate assessments are crucial. When determining if a patient is experiencing a stroke, suffering from a concussion, or dealing with substance abuse, pupillometry offers unparalleled precision. Thanks to the pioneering work of Dr. Olson and Dr. Aiyagari, pupillometry is set to become the standard for assessing brain health, covering conditions from concussions and strokes to cardiac arrest. This advancement will ultimately render the traditional use of flashlights for assessing pupils obsolete, ensuring more reliable and lifesaving evaluations in critical medical situations.