{{Short description|Medical procedure}} {{Infobox medical intervention | name = Induced coma | synonym = Medically induced coma | image = | caption = | alt = | pronounce = | specialty = Neurology, critical care medicine | ICD10 = | ICD9 = | ICD9unlinked = | CPT = | MeshID = | LOINC = | other_codes = | MedlinePlus = | eMedicine = }}
An '''induced coma'''{{spaced en dash}}also known as a '''medically induced coma''' ('''MIC'''), '''barbiturate-induced coma''', or '''drug-induced coma'''{{spaced en dash}}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.<ref name=Mariano2014/><ref name =An2018>{{cite journal | vauthors = An J, Jonnalagadda D, Moura V, Purdon PL, Brown EN, Westover MB | title = Variability in pharmacologically-induced coma for treatment of refractory status epilepticus | journal = PLOS ONE | volume = 13 | issue = 10 | article-number = e0205789 | date = 2018 | pmid = 30379935 | pmc = 6209214 | doi = 10.1371/journal.pone.0205789 | bibcode = 2018PLoSO..1305789A | doi-access = free }}</ref>
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,<ref name =An2018/> and in refractory intracranial hypertension following traumatic brain injury.<ref name=Mariano2014/>
Induced coma usually results in significant systemic adverse effects. The patient is likely to completely lose respiratory drive and require mechanical ventilation;<ref name="Ventilation">{{cite journal |last1=Gueye |first1=Papa N. |last2=Lofaso |first2=Frédéric |last3=Borron |first3=Stephen W. |last4=Mellerio |first4=Françoise |last5=Vicaut |first5=Eric |last6=Harf |first6=Alain |last7=Baud |first7=Frédéric J. |title=Mechanism of Respiratory Insufficiency in Pure or Mixed Drug-Induced Coma Involving Benzodiazepines |journal=Journal of Toxicology: Clinical Toxicology |date=January 2002 |volume=40 |issue=1 |pages=35–47 |doi=10.1081/clt-120002884 |pmid=11990203 }}</ref> gut motility is reduced;<ref name="GI Motility">{{cite journal |last1=Ladopoulos |first1=Theodoros |last2=Giannaki |first2=Maria |last3=Alexopoulou |first3=Christina |last4=Proklou |first4=Athanasia |last5=Pediaditis |first5=Emmanuel |last6=Kondili |first6=Eumorfia |title=Gastrointestinal dysmotility in critically ill patients |journal=Annals of Gastroenterology |date=15 March 2018 |volume=31 |issue=3 |pages=273–281 |doi=10.20524/aog.2018.0250 |pmid=29720852 |publisher=University of Crete Medical School, Department of Intensive Care Medicine |location=Crete, Greece |language=Greek |pmc=5924849}}</ref> hypotension can complicate efforts to maintain cerebral perfusion pressure and often requires the use of vasopressor drugs.<ref name="Brain dysfunction">{{cite journal |last1=Stevens |first1=Robert D. |last2=Nyquist |first2=Paul A. |title=Types of Brain Dysfunction in Critical Illness |journal=Neurologic Clinics |date=May 2008 |volume=26 |issue=2 |pages=469–486 |doi=10.1016/j.ncl.2008.02.004 |url=https://www.sciencedirect.com/science/article/pii/S0733861908000248 |access-date=27 August 2025 |publisher=Johns Hopkins University School of Medicine |location=Baltimore, MD |pmid=18514822 |issn=0733-8619|url-access=subscription }}</ref> Hypokalemia often results.<ref name="Hypokalemia">{{cite journal |last1=Aytuluk |first1=Hande Gurbuz |last2=Topcu |first2=Hulya |title=Severe hypokalemia and rebound hyperkalemia during barbiturate coma in patients with severe traumatic brain injury |journal=Neurocirugía |date=September 2020 |volume=31 |issue=5 |pages=216–222 |doi=10.1016/j.neucir.2019.12.003 |pmid=32146086 |publisher=Elsevier Ltd |language=Spanish|hdl=11491/7170 |hdl-access=free }}</ref> The completely immobile patient is at increased risk of bed sores as well as infection from catheters.<ref name="Bed sores">{{cite journal |author1=Sarah Lewis, PharmD |editor1-last=Han, M.D. |editor1-first=Seunggu |title=Medically Induced Coma: Everything You Need to Know |journal=Healthgrades |date=16 March 2022 |issue=Brain & Nerves |url=https://resources.healthgrades.com/right-care/brain-and-nerves/medically-induced-coma |access-date=27 August 2025 |publisher=Healthgrades Marketplace, LLC}}</ref><ref name="Pressure Ulcers">{{cite journal |last1=Hayashi |first1=Yuichi |last2=Shibata |first2=Hideaki |last3=Kudo |first3=Takuya |last4=Nishida |first4=Shohei |last5=Ishikawa |first5=Rie |last6=Moriya |first6=Chie |last7=Suzuki |first7=Akio |last8=Kimura |first8=Akio |last9=Inuzuka |first9=Takashi |title=Drug-induced Pressure Ulcers in a Middle-aged Patient with Early-stage Parkinson's Disease |journal=Internal Medicine |date=15 May 2018 |volume=57 |issue=10 |pages=1483–1486 |doi=10.2169/internalmedicine.9700-17 |pmid=29279501 |publisher=Gifu University Graduate School of Medicine |pmc=5995694}}</ref><ref name="Infection risk">{{cite journal |last1=Nseir |first1=Saad |last2=Makris |first2=Demosthenes |last3=Mathieu |first3=Daniel |last4=Durocher |first4=Alain |last5=Marquette |first5=Charles-Hugo |title=Intensive care unit-acquired infection as a side effect of sedation |journal=Critical Care |date=15 March 2010 |volume=14 |issue=2 |article-number=R30 |doi=10.1186/cc8907 |pmid=20226064 |publisher=BioMed Central Ltd. |doi-access=free |pmc=2887136}}</ref>
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 epilepticus, the inability to oxygenate with movement, et cetera justify the high risks of medically induced comas.<ref>{{Cite journal |last1=Eikermann |first1=Matthias |last2=Needham |first2=Dale M |last3=Devlin |first3=John W |date=May 12, 2023 |title='Multimodal, patient-centred symptom control': a strategy to replace sedation in the ICU |url=https://www.thelancet.com/pdfs/journals/lanres/PIIS2213-2600(23)00141-8.pdf |journal=The Lancet|volume=11 |issue=6 |pages=506–509 |doi=10.1016/S2213-2600(23)00141-8 |pmid=37187192 }}</ref>
Brain disruption from sedation can lead to an eight times<ref>{{Cite journal |last1=Pan |first1=Yanbin |last2=Yan |first2=Jianlong |last3=Jiang |first3=Zhixia |last4=Luo |first4=Jianying |last5=Zhang |first5=Jingjing |last6=Yang |first6=Kaihan |date=2019-07-10 |title=Incidence, risk factors, and cumulative risk of delirium among ICU patients: A case-control study |journal=International Journal of Nursing Sciences |volume=6 |issue=3 |pages=247–251 |doi=10.1016/j.ijnss.2019.05.008 |issn=2352-0132 |pmc=6722464 |pmid=31508442}}</ref> increased risk of the development of ICU delirium. This is associated with a doubled risk of mortality<ref>{{Cite journal |last1=Salluh |first1=Jorge I. F. |last2=Wang |first2=Han |last3=Schneider |first3=Eric B. |last4=Nagaraja |first4=Neeraja |last5=Yenokyan |first5=Gayane |last6=Damluji |first6=Abdulla |last7=Serafim |first7=Rodrigo B. |last8=Stevens |first8=Robert D. |date=2015-06-03 |title=Outcome of delirium in critically ill patients: systematic review and meta-analysis |url=https://www.bmj.com/content/350/bmj.h2538 |journal=BMJ |language=en |volume=350 |article-number=h2538 |doi=10.1136/bmj.h2538 |issn=1756-1833 |pmid=26041151|pmc=4454920 }}</ref> during hospital admission. For every one day of delirium, there is a 10% increased risk of death.<ref>{{Cite journal |last1=Ely |first1=E. Wesley |last2=Shintani |first2=Ayumi |last3=Truman |first3=Brenda |last4=Speroff |first4=Theodore |last5=Gordon |first5=Sharon M. |last6=Harrell |first6=Frank E. |last7=Inouye |first7=Sharon K. |last8=Bernard |first8=Gordon R. |last9=Dittus |first9=Robert S. |date=2004-04-14 |title=Delirium as a predictor of mortality in mechanically ventilated patients in the intensive care unit |journal=JAMA |volume=291 |issue=14 |pages=1753–1762 |doi=10.1001/jama.291.14.1753 |issn=1538-3598 |pmid=15082703 |url=http://nrs.harvard.edu/urn-3:HUL.InstRepos:33751441 }}</ref> Medically induced comas that achieve a RASS level of −4 or −5 are an independent predictor of death.<ref>{{Cite journal |last1=Shehabi |first1=Yahya |last2=Bellomo |first2=Rinaldo |last3=Reade |first3=Michael C. |last4=Bailey |first4=Michael |last5=Bass |first5=Frances |last6=Howe |first6=Belinda |last7=McArthur |first7=Colin |last8=Seppelt |first8=Ian M. |last9=Webb |first9=Steve |last10=Weisbrodt |first10=Leonie |last11=Sedation Practice in Intensive Care Evaluation (SPICE) Study Investigators |last12=ANZICS Clinical Trials Group |date=2012-10-15 |title=Early intensive care sedation predicts long-term mortality in ventilated critically ill patients |journal=American Journal of Respiratory and Critical Care Medicine |volume=186 |issue=8 |pages=724–731 |doi=10.1164/rccm.201203-0522OC |issn=1535-4970 |pmid=22859526}}</ref>
Although patients are not sleeping while sedated, they can experience hallucinations and delusions<ref>{{Cite journal |last1=Ali |first1=Mohammed |title=ICU Delirium |date=2023 |url=https://www.ncbi.nlm.nih.gov/books/NBK559280/ |journal=StatPearls |access-date=2023-08-15 |place=Treasure Island, FL |publisher=StatPearls Publishing |pmid=32644706 |last2=Cascella |first2=Marco}}</ref> 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.<ref>{{Cite journal |last1=Girard |first1=Timothy D. |last2=Jackson |first2=James C. |last3=Pandharipande |first3=Pratik P. |last4=Pun |first4=Brenda T. |last5=Thompson |first5=Jennifer L. |last6=Shintani |first6=Ayumi K. |last7=Gordon |first7=Sharon M. |last8=Canonico |first8=Angelo E. |last9=Dittus |first9=Robert S. |last10=Bernard |first10=Gordon R. |last11=Ely |first11=E. Wesley |date=July 2010 |title=Delirium as a predictor of long-term cognitive impairment in survivors of critical illness |journal=Critical Care Medicine |volume=38 |issue=7 |pages=1513–1520 |doi=10.1097/CCM.0b013e3181e47be1 |issn=1530-0293 |pmc=3638813 |pmid=20473145}}</ref>
Considering the high risks of medically induced comas, protocols such as the ABCDEF Bundle<ref>{{Cite journal |last1=Pun |first1=Brenda T. |last2=Balas |first2=Michele C. |last3=Barnes-Daly |first3=Mary Ann |last4=Thompson |first4=Jennifer L. |last5=Aldrich |first5=J. Matthew |last6=Barr |first6=Juliana |last7=Byrum |first7=Diane |last8=Carson |first8=Shannon S. |last9=Devlin |first9=John W. |last10=Engel |first10=Heidi J. |last11=Esbrook |first11=Cheryl L. |last12=Hargett |first12=Ken D. |last13=Harmon |first13=Lori |last14=Hielsberg |first14=Christina |last15=Jackson |first15=James C. |date=January 2019 |title=Caring for Critically Ill Patients with the ABCDEF Bundle: Results of the ICU Liberation Collaborative in Over 15,000 Adults |journal=Critical Care Medicine |volume=47 |issue=1 |pages=3–14 |doi=10.1097/CCM.0000000000003482 |issn=1530-0293 |pmc=6298815 |pmid=30339549}}</ref> and PADIS guidelines<ref>{{Cite web |title=SCCM {{!}} PADIS Guidelines |url=https://sccm.org/Clinical-Resources/ICULiberation-Home/Guidelines |access-date=2023-08-15 |website=Society of Critical Care Medicine (SCCM)}}</ref> 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<ref>{{Citation |last1=Smith |first1=Sarah |title=Post-Intensive Care Syndrome |date=2023 |url=https://www.ncbi.nlm.nih.gov/books/NBK558964/ |work=StatPearls |access-date=2023-08-15 |place=Treasure Island, FL |publisher=StatPearls Publishing |pmid=32644390 |last2=Rahman |first2=Omar}}</ref> and may require extended physical, cognitive, and psychological rehabilitation.
== Theory == Barbiturates reduce the metabolic rate of brain tissue, as well as the cerebral blood flow. With these reductions, the blood vessels in the brain narrow, resulting in a shrunken brain, and hence lower intracranial pressure. The hope is that, with the swelling relieved, the pressure decreases and some or all brain damage may be averted. Several studies have supported this theory by showing reduced mortality when treating refractory intracranial hypertension with a barbiturate coma.<ref>{{cite journal | vauthors = | title = The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Use of barbiturates in the control of intracranial hypertension | journal = Journal of Neurotrauma | volume = 17 | issue = 6–7 | pages = 527–530 | year = 2000 | pmid = 10937896 | doi = 10.1089/neu.2000.17.527 | publisher = Mary Ann Liebert, Inc. }}</ref><ref>{{cite journal | vauthors = Lee MW, Deppe SA, Sipperly ME, Barrette RR, Thompson DR | title = The efficacy of barbiturate coma in the management of uncontrolled intracranial hypertension following neurosurgical trauma | journal = Journal of Neurotrauma | volume = 11 | issue = 3 | pages = 325–331 | date = June 1994 | pmid = 7996586 | doi = 10.1089/neu.1994.11.325 }}</ref><ref>{{cite journal | vauthors = Nordby HK, Nesbakken R | title = The effect of high dose barbiturate decompression after severe head injury. A controlled clinical trial | journal = Acta Neurochirurgica | volume = 72 | issue = 3–4 | pages = 157–166 | year = 1984 | pmid = 6382945 | doi = 10.1007/BF01406868 | s2cid = 12215655 }}</ref>
About 60% of the glucose and oxygen used by the brain is meant for its electrical activity and the rest for all other activities such as metabolism.<ref>{{cite web | title= Update on Techniques for Neuroprotection during Hypothermic Arrest | publisher= Society of Cardiovascular Anesthesiologists | author= Grocott HP | url= http://www.scahq.org/files/Conference_2014_Annual_Syllabi_Sessions/SCA_2014_syllabus_Grocott_Update_on_techniques_for_neuroprotection_during_hypothermic_arrest.pdf | access-date= 14 April 2016 | quote= approximately 60% of CMRO2 is utilized for neuronal function (with the remainder being required for cellular integrity) | archive-url= https://web.archive.org/web/20160423192027/http://www.scahq.org/files/Conference_2014_Annual_Syllabi_Sessions/SCA_2014_syllabus_Grocott_Update_on_techniques_for_neuroprotection_during_hypothermic_arrest.pdf | archive-date= 23 April 2016 }}</ref> When barbiturates are given to brain injured patients for induced coma, they act by reducing the electrical activity of the brain, which reduces the metabolic and oxygen demand.<ref>{{cite web| title =Cerebral protection and resuscitation| publisher =CNS Clinic – Jordan – Amman| url =http://www.neuroanesthesia.info/cerebralprotection.htm| access-date =16 April 2016| quote =The primary mechanism of protection involves a reduction in CMRo2 of up to 55% to 60% at which point the EEG becomes isoelectric.| archive-date =4 November 2020| archive-url =https://web.archive.org/web/20201104172132/http://www.neuroanesthesia.info/cerebralprotection.htm}}</ref> Their action limits oxidative damage to lipid membranes and may scavenge free radicals. They also lead to reduced vasogenic edema, fatty acid release and intracellular calcium release.<ref name=Mariano2014/>
The infusion dose rate of barbiturates is increased under monitoring by electroencephalography until burst suppression or cortical electrical silence (isoelectric "flatline") is attained.<ref>{{cite web| title =Barbiturate Coma| publisher =Trauma.org| url =http://www.trauma.org/archive/anaesthesia/barbcoma.html| access-date =16 April 2016| quote =Therapeutic EEG response: burst suppression or cortical electrical silence (with preservation of SSEP and BAEF).| archive-url =https://web.archive.org/web/20160819000601/http://www.trauma.org/archive/anaesthesia/barbcoma.html| archive-date =19 August 2016}}</ref> Once there is improvement in the patient's general condition, the barbiturates are withdrawn gradually and the patient regains consciousness.
Controversy exists over the benefits of using barbiturates to control intracranial hypertension. Some studies have found that barbiturate-induced coma can reduce intracranial hypertension but does not necessarily prevent brain damage.<ref name=Mariano2014/> Furthermore, the reduction in intracranial hypertension may not be sustained. Some randomized trials have failed to demonstrate any survival or morbidity benefit of induced coma in diverse conditions such as neurosurgical operations, head trauma,<ref>{{cite journal | vauthors = Schwartz ML, Tator CH, Rowed DW, Reid SR, Meguro K, Andrews DF | title = The University of Toronto head injury treatment study: a prospective, randomized comparison of pentobarbital and mannitol | journal = The Canadian Journal of Neurological Sciences. Le Journal Canadien des Sciences Neurologiques | volume = 11 | issue = 4 | pages = 434–440 | date = November 1984 | pmid = 6440704 | doi = 10.1017/s0317167100045960 | doi-access = free }}</ref> intracranial aneurysm rupture, intracranial hemorrhage, ischemic stroke, and status epilepticus. If the patient survives, cognitive impairment may also follow recovery from the coma.<ref>{{cite journal | vauthors = Schalén W, Sonesson B, Messeter K, Nordström G, Nordström CH | title = Clinical outcome and cognitive impairment in patients with severe head injuries treated with barbiturate coma | journal = Acta Neurochirurgica | volume = 117 | issue = 3–4 | pages = 153–159 | year = 1992 | pmid = 1414516 | doi = 10.1007/BF01400613 | s2cid = 23032307 }}</ref> Due to these risks, barbiturate-induced coma should be reserved for cases of refractory intracranial pressure elevation.<ref name=Mariano2014>{{cite book | vauthors = Mariano GL, Fink ME, Hoffman C, Rosengart A | date = 2014 | chapter = Intracranial pressure: monitoring and management. | veditors = Hall JB, Schmidt GA, Kress JP | title = Principles of Critical Care | edition = 4th | publisher = McGraw Hill | chapter-url = https://accessmedicine.mhmedical.com/content.aspx?bookid=1340§ionid=80036194 | isbn = 978-0-07-173881-1 }}</ref>
== See also == * Insulin shock therapy * Traumatic brain injury
== References == {{Reflist|30em}}
== External links == *[https://www.livescience.com/39483-what-is-a-medically-induced-coma.html Medically induced Coma] – LiveScience
{{Intensive care medicine}} {{Authority control}}
Category:Neurology procedures Category:Intensive care medicine Category:Coma