Induced coma

An induced coma – also known as a medically induced coma (MIC), barbiturate-induced coma, or drug-induced coma – is a temporary coma (a deep state of unconsciousness) brought on by a controlled dose of an anesthetic drug, often a barbiturate such as pentobarbital or thiopental. Other intravenous anesthetic drugs such as midazolam or propofol may be used.

Drug-induced comas are used to protect the brain during major neurosurgery, as a last line of treatment in certain cases of status epilepticus that have not responded to other treatments, and in refractory intracranial hypertension following traumatic brain injury.

Induced coma usually results in significant systemic adverse effects. The patient is likely to completely lose respiratory drive and require mechanical ventilation; gut motility is reduced; hypotension can complicate efforts to maintain cerebral perfusion pressure and often requires the use of vasopressor drugs. Hypokalemia often results. The completely immobile patient is at increased risk of bed sores as well as infection from catheters.

The presence of an endotracheal tube and mechanical ventilation alone are not indications of continuous sedation and coma. Only certain conditions such as intracranial hypertension, refractory status epileptics, the inability to oxygenate with movement, et cetera justify the high risks of medically induced comas.

Brain disruption from sedation can lead to an eight times increased risk of the development of ICU delirium. This is associated with a doubled risk of mortality during hospital admission. For every one day of delirium, there is a 10% increased risk of death. Medically induced comas that achieve a RASS level of −4 or −5 are an independent predictor of death.  

Although patients are not sleeping while sedated, they can experience hallucinations and delusions that are often graphic and traumatizing in nature. This can lead to post-ICU PTSD after hospital discharge. Patients that develop ICU delirium are at 120 times greater risk of long-term cognitive impairments.

Considering the high risks of medically induced comas, protocols such as the ABCDEF Bundle and PADIS guidelines have been developed to guide ICU teams to avoid unnecessary sedation and comas. ICU teams that master these protocols to keep patients as awake and mobile as possible are called "Awake and Walking ICUs". These are teams that only implement medically induced comas when the possible benefits of sedation outweigh the high risks during specific cases. 

Survivors of prolonged medically induced comas are at high risk of suffering from post-ICU syndrome and may require extended physical, cognitive, and psychological rehabilitation.