The absence of brain stem function is documented by conducting the following tests:
• Absence of Pupillary reflex response to light
• Absence of Corneal reflexes
• Absence of Vestibulo-ocular reflex
• Absence of Cranial nerve response to pain
• Absence of Gag and Cough reflexes
• Apnoea Test
Pupillary Reflexes: To check for absent pupillary response to light, bright pen torchlight should be used in a darkened room. It should be made sure that no eye drops to dilate the pupils have been used in the four hours previously. The pupils may not be necessarily fixed and dilated in the brainstem dead patients; however there should be no pupillary response to light.
Corneal Reflexes: Moist cotton tipped swab should be used and firm pressure should be applied to the cornea without damaging it.
Vestibulo-Ocular Reflexes: This testing involves instilling 20ml of ice-cold water into the external auditory canal and looking at eyeball movements of either eye for about a minute. No eyeball movement indicates absence of reflex. Presence of ruptured eardrums or discharge from the ear prevents this test from being performed.
Gag and Cough Reflexes: This requires temporary disconnection from the ventilator. A cotton tipped swab can be used to stimulate the posterior pharynx to look for a response. Experienced ICU staff usually notice a progressive loss of response during the evolution of brainstem death when performing the routine suction of airways and oropharynx.
Grimacing of the face to a painful stimulation: This is a normal response in a normal condition and is absent in brainstem death situation. A firm supra-orbital pressure (trigeminal nerve) should be used to check this cranial reflex. Pin pricks should not be used to test this response.
Dolls Head Eye Phenomenon (Testing for oculo-cephalic reflex): This is one test that can be done to know if the brainstem is still alive. If this test is positive then other tests to establish brain stem death can be postponed. One may need to disconnect the patient from the ventilator for 15 to 20 second to perform this test. To do this test the physician holds the patients head between his hands and moves the head from side to side through 180 degrees. The clinician should hold the head to one side for 3 to 4 seconds and look at the simultaneous eye movement to that side. A similar movement is done to the opposite side and eye movement is noticed. In a normal fully alert individual the eyes move with the head and there is only a very fractional delay. In the case of Brain Stem Death, the eyes will not move with the head.
Apnoea Test: This is the last test done after all tests above are positive. The aim of apnoea test is to establish death of the respiratory centre in the brain stem. It is done to check whether there is any spontaneous breathing or not. If the patient cannot breathe on his/her own, after all other tests are positive then they can be declared Brain Stem Dead.