Surgery – Diagnostic testing – Touch or pain response of skin
Reexamination Certificate
2000-03-23
2002-07-09
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Touch or pain response of skin
C600S300000
Reexamination Certificate
active
06416480
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems and methods for computerized monitoring the levels of consciousness of patients admitted to medical units such as intensive care units, emergency rooms, operating rooms, etc. Specifically it automates and ultimately completely eliminates the need for human assessment of the most commonly used coma score—the Glasgow Coma Score (GCS), while still using the same scale.
2. Description of the Prior Art
The Glasgow Coma Scale (GCS) was proposed by Teasdale and Jennett (Teasdale and Jennett 1974) and further elaborated Avezaat et. al., “A Scoring Device For The Level Of Consciousness: The Glasgow “Coma” Scale”
Ned Tijdschr Geneeskd
121 2117-21 (1977). GCS is the most widely used scoring system in quantifying level of consciousness following traumatic brain injury. It is used primarily because it is simple, has a relatively high degree of inter-observer reliability, and because it correlates well with outcome following severe brain injury.
GCS is comprised of three components: eye opening—E; motor response—M; and verbal response—V. (1) The eye opening is scored on a scale from 1 to 4. A score of 1 is assigned to a patient who is incapable of opening his or her eyes. In contrast, a 4 is assigned if the patient opens his or her eyes spontaneously. If a patient is unable to open his/her eyes spontaneously, but is capable of responding to verbal commands, such as “open your eyes”, a score of 3 is assigned. If eye opening cannot be elicited by a verbal command, but can be caused by applying a painful stimulus, the response is scored as 2.
(2) The motor response is scored on a scale from 1 to 6. A maximum score of 6 is assigned to a patient capable of obeying verbal commands such as “Show me two fingers”. If the patient does not react to verbal commands, but can localize painful stimuli by moving his or her arm toward the pain source in an attempt to remove the irritant, he or she will receive a score of 5. A patient only capable of a withdrawal response (a reflexive non-localizing movement) is assigned a score of 4. A score of 3 is given to an abnormal flexion response in which the arms are flexed at the elbows. If the motor response is an abnormal rigid extension (“brain stem level”) the score is 2. A minimum score of 1 is assigned to a patient who produces no motor response to verbal or pain stimulus.
(3) The verbal response is scored on a scale from 1 to 5. A maximal verbal score of 5 is given to a patient who is oriented and converses cohesively. A patient who can speak intelligibly, but is disoriented (i.e., unable to answer questions such as “Who are you?” or “Where are you?”) is assigned a verbal score of 4. A score of 3 is given to a patient who utters inappropriate words in response to verbal questions. If the patient produces only incomprehensive sounds he or she will receive a score of 2. The absence of a verbal response is designated as 1 on the verbal scale. Often patients in the ICU are intubated; resulting in a mechanical obstruction of their airways which prevents them from speaking. In such cases a verbal score of 1 v is logged. The total maximal Glasgow Coma Score is 15 while the minimal score is 3. Table 1 is a summary of the Glasgow Coma Scale.
TABLE 1
Summary of the Glasgow Coma Scale
Eye
Best Verbal
Best Motor Response
Opening (E)
Response (V)
(M) upper limbs
4 = Spontaneous
5 = Normal
6 = Normal (obeys
conversation (oriented)
commands)
3 = To
4 = Disoriented
5 = Localizes to pain
voice
incoherent conversation
2 = To
3 = Words, but not
4 = Withdraws to pain
pain
coherent
(normal flexion)
1 = None
2 = No words,
3 = Decorticate posture
incomprehensive only
(abnormal flexion)
sounds
1 = None
2 = Decerebrate
(extension)
1 = None
Total GCS = E + V + M
The following example demonstrates a GCS assessment performed on a comatose patient. Prior to the GCS assessment the patient is situated in a standard position (hands on either side of the chest). The nurse is unable to observe spontaneous eye movements and subsequently determines that the patient is unconscious. In an attempt to elicit a response the nurse gives verbal commands such as “Jack open your eyes”. This is repeated few times, each time successively louder. The patient's eyes remain closed, however, so she proceeds to forcefully pinch (i.e., painfully) the skin on his shoulders (above the deltoid muscle). The patient does not localize the pain (does not move hand toward the pain source), so the nurse pinches skin on the inner side of his biceps, which the patient localizes, or tickles the patient's nose with a Q-tip—an irritant which is localized as well. This is the end of the GCS exam. The patient was scored as GCS 7-8v (E2; M4-5; V1v).
FIG. 1
shows a cartoon view of the standard GCS assessment procedure as performed by nurses in hospitals around the world. It shows the various eyes, motor, and verbal responses as observed during GCS assessment.
The GCS assessment is part of standard patient care and is commonly incorporated in most hospitals' written Policies and Practices manual. Specifically, in a neurosurgery ICU the GCS of every patient is assessed and manually recorded in the patient's chart every hour or entered in a computer. Routinely, an attending nurse performs the procedure; however, the attending physician can also assess the GCS during his or her rounds. Normally it takes about two to five minutes to get the GCS depending on the patient's state of consciousness. Besides neurosurgery ICUs, where the patients are usually in a somewhat impaired state of consciousness or comatose, the assessment of GCS is recommended every 4 hours in all non-neurological ICUs and a minimum of once a shift for patients on the hospital floor. GCS is also commonly used in the emergency room.
There are several reasons why it is desirable to have an automated method for measuring the GCS:
1) Availability of qualified human assessors: Unpredictable changes of the patient's level of consciousness can occur any time, day and night, and critical care personnel might not always be at hand to capture such changes. An AGCS system can be programmed to assess the GCS automatically and repetitively as frequently as necessary.
2) Subjectivity and frequency of assessment: Since the assessment of GCS requires human intervention (clinical procedure by nurses or doctors), it is often subjective, and can not be always performed on a regular basis.
3) Variability and accuracy: The accuracy of the Glasgow Coma Score is critical. Despite its demonstrated reproducibility in published works, in actual practice there is substantial variability in performing, scoring and recording the GCS by bedside nurses (these are the health care workers who most frequently perform this test as a routine evaluation). It is not at all uncommon to see an abrupt change in the recorded GCS when there is “change of shift”, when a new nurse comes on duty: “Scoring is often performed incorrectly (e.g. nurses commonly and inappropriately score patients according to worst response” and therefore it is often inaccurate.
4) Reliability and reproducibility of the GCS in actual practice is important for physician monitoring of patient status. Decisions regarding non-invasive or invasive diagnostic testing or therapeutic management are often made based on changes in GCS. For instance, a significant (e.g., 2 point) decrease in GCS often will lead to the performance of a cranial CT scan, or an invasive cerebral angiogram, which may further result in a change in the patient's treatment. If the GCS has been scored inaccurately, the patient will have been exposed to a potentially risky and unnecessarily costly procedure, or conversely, a change in mental state with implications for early intervention may be missed. The AGCS system will reliably and reproducibly provide the Glasgow coma score.
5) Inadequate personnel t
Dawes Daniel L.
McCrosky David
Myers Dawes & Andras LLP
Winakur Eric F.
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