This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'The causes of systemic secondary insult to injured brain include all of the following except - \nSelect and explain. \nA. Hypercapnia, B. Hypoxemia, C. Hypotension, D. Hypothermia', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Patients with primary brain injury whether due to any trauma or stroke are at significant risk for some secondary\xa0ischemic brain injury?\n\nCauses of secondary brain injury are - Hypotension\n\nHypotension should be strictly avoided as significant hypotensive events as short as 10 minutes in duration have\xa0been shown to adversely influence the outcome after traumatic brain injury.\nEven in patients with stroke or head trauma, who do not require I.C.P. monitoring, close attention to adequate\xa0cerebral perfusion is required.\n\nHypoxia\n\nHypoxia (percutaneous oxygen saturation < 90%) alone, or in combination with hypotension, also leads to\xa0secondary brain injury.\n\nFever\n\nFever can adversely affect the outcome of the patient.\nSo aggressive control of fever with a goal of normothermia is warranted and can usually be achieved with\xa0antipyretic medication and cooling blankets.\n\nHyperglycemia\n\nThis is also associated with worsened clinical outcome after stroke and trauma.\nIntravenous insulin is encouraged for control of hyperglycemia as this allows better regulation of serum glucose\xa0level than subcutaneous insulin.\nA reasonable goal is to maintain serum glucose level at < 160 mg/dl.\n\nAlso know,\n\nEffect of hypothermia on secondary brain injury.\n\nThe drop in temperature inhibits the release of the excitatory neurotransmitter glutamate and attenuates the release\xa0of dopamine, in brain ischemia animal models, suggesting a protective effect of hypothermia in brain injury.\n\nSecondary brain injury can be a major determinant in the outcome of the patient so strategies for minimizing\xa0secondary brain insults are an integral part of critical care of all patients.\nEpisodes of secondary brain insults are usually not associated with apparent neurological worsening, rather they\xa0lead to cumulative injury, which manifest as higher mortality or worsened long term functional outcome.\nThus clinical strategies to prevent secondary brain insults involve close monitoring of vital signs and risk factors\xa0to prevent secondary ischemia.', 'role': 'assistant'}]