Though declaring a person dead is a simple routine, but undoubtedly a critical moment for a doctor. It is an organized step-wise process of patient’s examination to assess the brain functions. Death must be declared by a medical doctor or medical professional.
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The dead person is always pulse-less. You cannot feel any radial pulse in both fore-arms or any pulse anywhere in the body. The heart pumps blood out into the body through vessels producing a pressure onto their walls. This pressure produces and amplitude in the vessel wall that is felt as a “Pulse”. If the heart is not functioning, no pulse can be felt. However, only pulselessness does not confirm that the patient is dead. In several conditions, pulse may not be recordable. In other words, a working heart may be too weak to produce pulse. Carotid pulses are better to be examined.
No Blood Pressure
No blood pressure can be recorded in both upper limbs or anywhere in a dead person. In a dead person, heart stops working! The heart pumps blood out into the body through vessels producing a pressure onto their walls. This pressure is named as “Blood Pressure”. If the heart is not working, no blood pressure can be recorded. However, only B.P. lessness does not confirm the patient is dead. In several conditions, blood pressure may not be recordable. In other words, a working heart may be too weak to produce enough power to give a recordable blood pressure.
|Blood Pressure (Source: www.drelaine.com)|
No Heart Sounds
No heart sounds can be heard over the chest of a dead person at least for one minute. Simply, when the heart is dead, no sound will be produced. If you are in doubt, ask to your colleague to hear the patient’s heart (auscultate).
No Respiratory Sounds
No respiratory or other breathing sounds can be heard over chest. No respiratory movements are observed. When the brain is dead, breathing movements and sounds stop.
No Response to Deep Painful Stimulus
The dead person does not respond to any deep painful stimulus. Deep painful stimulus can be applied by sharply pushing or rubbing against the sternum (central bone of chest).
|Painful Stimulus/ Pressing the Sternum|
Absent Pupillary Light Reflex
It refers to the change in the diameter of pupil in response to light. The pupil dilates in dim light (darkness) while constricts in high or intense light, regulating the light entering the eye. It assesses the brain function (mid-brain) whether it is functioning or not. In a dead patient, pupillary light reflex is absent. It means the both pupils do not respond to light and the pupils are seen as bilaterally fixed dilated. However, some drugs (e.g. mydriatic eye drops, anticholinergic drugs, tricyclic antidepressant overdose) and third nerve palsy may dilate the pupils so that they fail to respond to light. So, other signs must be considered along with papillary light reflex. Afferent limb (sensory limb) of this reflex is made by first cranial nerve (optic nerve, CN-I) while efferent limb (motor limb) is made by third cranial nerve (Oculomotor nerve, CN-III).
|Pupillary Light Reflex|
Absent Corneal Reflex
Corneal reflex or blink reflex refers to the blinking of eyelids by the stimulation of cornea. Corneal reflex can be checked by brushing something like cotton swab against the corneal surface. It is also mediated by brain (a centre located in pons of midbrain). It is absent too in a dead person. Afferent limb (sensory limb) of this reflex is made by the first branch (ophthalmic nerve, V1) of the fifth cranial nerve (Trigeminal nerve, CN-V) while efferent limb (motor limb) is made by branches (temporal and zygomatic nerves) of seventh cranial nerve (Facial nerve, CN-VII).
Straight-Lined Electrocardiograph (ECG)
The ECG of a dead person shows straight line. Straight line refers to absent electric signals in the heart. However, sometimes ECG shows some irregular and abnormal drawings that may be due to injected drugs like atropine and adrenaline. So, clinician should wait till the ECG is straight before declaring the patient is dead.
Absent Oculocephalic ReflexOculocephalic reflex or vestibulo-ocular reflex refers to the conjugate but opposite movements of eyeballs when the head is rotated to one side. For instance, if the head is moved to the right, the eyeballs will move to the left. These are the reflex eye movements meant for the stabilization of the image on retina. In other words, when an examiner moves or rotates the head of the patient side to side, the eyes remain fixated on the examiner's face. Sensory signals of oculocephalic reflex are carried through vestibular system (semi-circular canals) to the eighth cranial nerve (vestibular nerve, CN-VIII), from where the signals reach the brain stem. From the brain stem, motor signals reach the ocular muscles through sixth cranial nerve (abducens nerve, CN-VI ) and third cranial nerve (oculomotor nerve, CN-III). In the dead, this reflex is absent. It is also called as "doll's eye reflex" or "doll's eye movements". Doll's eye maneuver is contraindicated in the patients with brain-stem injury.
|Oculocephalic reflex (Source: www.wikilectures.eu)|
Absent Gag Reflex (Pharyngeal Reflex)In this test, the back of the throat (i.e. the posterior wall of pharynx) is touched with a cotton swab or a suction tube. It causes the back of the throat to contract (i.e. contraction of pharyngeal muscles) producing cough or gag. The sensory fibers of the gag reflex are carried by glossophaygeal nerve (CN-IX) while the motor fibers by vagus nerve (CN-X). Gag reflex is absent in brain dead person. Pharyngeal reflex is usually done in patients who present with deep coma or who have been on ventilator or when the doctor is not sure about "the brain is dead".
|Gag Reflex (Source: www.clinicalexams.co.uk)|