Glasgow Coma Scale - Addendum to "Managing An Unconscious Patient" by Dr JB LIm

The blogger received a request by the Great Sifu Dr JB Lim to include the following addendum to his article earlier posted into this blog (refer to: http://taionn.blogspot.com/2012/08/managing-unconscious-patient-by-dr-jb.html ) and the blogger is more than pleased to oblige:

Management of a patient with low LOC:

In the event a patient becomes unconscious, an emergency physician, a paramedic or a first responder can make a quick assessment of his Level of Consciousness (LOC) using a number of methods.

AVPU:

The simplest assessment to use is known as the AVPU (Alertness when questioned, responsiveness to Verbal stimulus by asking or shouting if he is okay, responsiveness to Pain by pinching to elicit moaning or withdrawal from pain, or if he is Unresponsive to all). The patient can also be assessed for Alertness, Confusion, Drowsiness, and Unresponsiveness.

GCS:

A more trained emergency physician normally uses the Glasgow Coma Scale or GCS to determine the neurological status. This provides a more objective, and reliable method of assessing the LOC by giving scores from a minimum of 3 for deep coma to 15 for fully alert.

The GCS was first used by emergency doctors, paramedics and first respondents to assess the level of consciousness after head injury, but can now be used for all acute medical and trauma cases, or in patients in the intensive care of hospitals.

This scale looks at eye, verbal and motor responses. The three values are scored separately as well as their sum. The lowest possible GCS score is 3 to mean deep coma or even death, while the highest is 15 to grade a fully awake person.

However, it must be noted that primary brain injuries sustained at the time of trauma cannot be reversed. In order to minimize secondary brain damage, the initial management of any patient with Traumatic Brain Injury (TBI), or intracranial injury is to prevent low oxygen perfusion to the brain (hypoxia), to maintain an adequate BP so as to establish Cerebral Perfusion Pressure (CPP) in order to recognize and treat surgically correctable intracranial lesions. Additionally, other concomitant injuries should also be identified and stabilized.

Prehospital Phase

The prehospital phase during the first hour (The Golden Hour) is perhaps the most important interval in establishing the ultimate outcome after the TBI event. The initial goals of an emergency care giver are to maintain a patent airway, begin fluid resuscitation, immobilize the cervical and thoracolumbar spine, and assess the level of consciousness, followed by a rapid transport to a trauma center with neurologic services, and not to any ‘nearest hospital’

It is estimated that about half of TBI patients are reported to be hypoxic at the site of the accident. It was found this correlates with an increased in mortality. A case control study indicated that immediate prehospital intubation by a trained emergency provider significantly reduced the incidence of mortality in patients with TBI.

It is suggested the importance of early orotracheal intubation in patients with a GCS score of less than 8. Intubation can usually be accomplished without any sedation or medication and should be well within the clinical skills of a paramedic.

The Monro-Kellie Theory

My feeling as a prehospital care provider as for all ambulance crew with advanced training in trauma, is to understand the pressure-volume relationship between ICP (Intracranial Pressure), volume of CSF (cerebrospinal fluid), blood supply and brain tissue, as well as the cerebral perfusion pressure (CPP), in what is known as the Monro-Kellie doctrine or the Monro-Kellie hypothesis.

The Monro-Kellie hypothesis states that the cranial compartment is incompressible, and the volume inside the cranium has a fixed volume. The cranium and its constituents (blood, CSF, and brain tissue) create a state of volume equilibrium, such that any increase in volume of one of the cranial constituents must be compensated by a decrease in volume of another. Essentially, this is what Monro-Kellie hypothesis is all about.

In short, perfusion to the brain is compromised due to a decrease in blood flow if there is an increased in the ICP within the fixed compartmental volume of the skull.

Thus it is crucial for all advanced emergency care providers to be able to manage a head injury as fast as possible.

Regards,

Jb lim

Retired Regional Staff Officer and Trainer

St John Ambulance Malaysia