“Brain dead but alive!” There are very few conditions when a person has no brainstem activity and is declared brain dead by the doctors. Physicians must take great caution in declaring patients with these diagnoses as they are actually alive.
A true story of a patient in our ward …
While conducting rounds in the medical ward of PIMS hospital, two intubated patients were lying close to each other and were ventilated through ambu-bags as no bed was available in the medical intensive care unit.
The First patient …
One patient was around 50 years with diabetes, hypertension and chronic lung disease who was in respiratory failure. He was intubated on arrival to the emergency department and was given breaths by the attendants through ambu-bag for the last 12-16 hours.
The other patient …
The other patient was a 16 years old girl with a history of neurotoxic snakebite one day before presenting to the emergency department. She was deeply unconscious, in respiratory failure, had fixed dilated pupils, absent dolls eye and gag reflexes. She was intubated and breaths were given by the attendants since admission. She had no other comorbid conditions.
Which patient …
Meanwhile, a bed was vacated in the medical ICU and we had to decide to shift one of the patients. Although both were candidates for ventilator support, one of them had to be shifted first. The girl had arrived before the man but she had absent brainstem signs, while the man had multiple co-morbid conditions and might not survive even with ICU care.
Brain dead but alive …
Although absent brainstem signs mean that the patient is brain dead. This could mean that she would not gain consciousness and occupy a precious ICU bed without any good outcome. In fact, she was labeled as braindead!. This tempted us to shift the older individual, however, after discussion, the girl was shifted to the medical ICU, put on a ventilator and high doses of anti-snake venom were given. Fortunately, she responded to the treatment and gained consciousness and was discharged after about ten days in a walking, talking and laughing state.
Lets briefly discuss the importance of the above story of this brain dead but alive young female.
Before labeling the person as brain dead, the following criteria must be met.
- Pupils dilate and do not react to light (fixed dilated pupils)
- Loss of corneal reflex (absent blinking reflex on touching the corner of the eye)
- Positive Dolls eye reflex (oculocephalic reflex) – the eyes normally move opposite to the direction of the head. In brain-dead patients, both the eyes and the head move in the same direction.
- Loss of oculovestibular reflex – absent eye movements when cold ice is poured into the ear
- Absent gag reflex when the back of the throat is touched
- Absent respiration when ventilator support is switched off.
- Failure of the heart rate to increase by 5 beats per minute when 1 -2 mg of atropine is given
- Positive apnea test i.e. absent respiratory efforts when the ventilator is switched off and the pCO2 rises to above 60 mmHg or increase by 20 mmHg from the baseline in the presence of a normal PO2.
- An EEG shows no brain activity at all.
Brain death is defined as the loss of complete brain functions. It includes both voluntary and involuntary functions like respiration and the autonomic system. In contrast to brain death, coma is a transient loss of higher brain functions and persistent vegetative state is the permanent loss of higher brain functions. In both these conditions, the involuntary function of the brain is maintained.
A vegetative state is the partial or complete loss of higher mental functions. In this condition, patients are arousable but not aware of their surroundings. This is in contrast to a coma in which the patient lacks both awareness and wakefulness.
Patients who develop locked-in syndrome are aware of their surroundings but cannot move. Only the eye muscles remain functional and the patient can communicate through the eyes.
Conditions mimicking brain death
- Shock/ hypotension
- Hypothermia -temperature < 32°C
- Drugs known to alter neurologic, neuromuscular function and electroencephalographic testing, like anesthetic agents, neuroparalytic drugs, barbiturates, benzodiazepines, and alcohols.
- Brain stem encephalitis.
- Guillain- Barre’ syndrome.
- Encephalopathy associated with hepatic failure, uremia and hyperosmolar coma
- Severe hypophosphatemia.
Brain dead but alive – Neurotoxic snake bite
Patients with neurotoxic snakebite can have a variety of symptoms ranging from mild ptosis to respiratory failure, coma and complete loss of brainstem reflexes. Patients may develop fixed dilated pupils, absent gag reflex and have absent corneal and vestibule-cochlear reflexes. EEG abnormalities may be present and patients have a variable degree of encephalopathy.
Brain dead but alive – Barbiturate poisoning
Barbiturates are known for their hypnotics, anesthetics and anti-epileptic properties. Barbiturates, in a dose-dependent manner, can reversibly inhibit all excitable tissues especially the central nervous system. Neurological effects start from calming to sleepiness, unconsciousness, coma, surgical anesthesia, and finally fatal respiratory and cardiovascular depression. It leads to coma with absent reflexes when taken in high doses, usually when plasma concentration exceeds above 100 mcg/ml.
Brain dead but alive – Hypothermia
Severe hypothermia (below 30 C) is associated with cardiovascular and neurologic effects. Patients become drowsy and become comatose. The skin becomes cyanosed. The heart rate falls and respiration becomes slow progressing to full respiratory arrest. The pupils become dilated with absent brainstem reflexes and the EEG may also be suggestive of brain death. A case report of a young child with hypothermia who survived after six hours of CPR emphasizes that patients with hypothermia should be resuscitated with a full protocol for a longer period and till the core body temperature is above 32 c.
Brain dead but alive – Acute Pandysautonomia
Acute pandysautonomia is an extremely rare variant of Guillain Barre syndrome characterized by postural hypotension, pupillary abnormalities, bowel and bladder symptoms. In severe cases, patients can present with absent reflexes, muscle weakness, and respiratory failure. Absent dolls eye reflex, gag reflex, and fixed dilated pupils may lead the physicians to declare the patient as dead. Intravenous Immunoglobulins is the treatment of choice.
physicians need to be extra cautious in declaring a patient as brain dead and weaning him/ her off ventilatory support prior to excluding the above-mentioned diseases. Repeated neurological examination and EEG may be done to confirm brain death. Furthermore, these patients should not be devoid of critical care and ventilator support.