Benefits Of Ketamine Versus Propofol In Acute Traumatic Brain Injuries With Elevated Intracranial Pressure

Ketamine is a widely used medication that can be administered for the delivery of anesthesia as well as analgesia while supporting hemodynamics. A commonly taught concept based on early research is that ketamine should not be administered to those with acute brain injuries. Early research had stated that ketamine can cause a dangerous increase in intracranial pressure (ICP) and thus a decrease in cerebral perfusion and oxygenation in those with traumatic brain injuries (TBI) (Takeshita et al., 1972). More recent research has shown that ketamine may be efficacious for patients with TBIs and can decrease ICP (Dengler et al., 2022). In comparison, the use of propofol for induction is a widely accepted and much more common practice for induction with the benefits of possibly avoiding a detrimental increase in ICP (Adembri et al., 2007). This literature review was conducted to identify the benefits and safety of cerebral hemodynamics with the use of ketamine versus propofol for induction in the adult population presenting for decompressive craniotomy. A literature review of confounding evidence has been conducted, including electronic bibliographic databases, relevant articles, and several anesthesia textbooks. In searching the databases the focus was on studies using ketamine and propofol with acute brain injuries and their effects on intracranial pressure in patients presenting for decompressive craniotomies. There are currently 31 research studies and systematic reviews included. Positive clinical outcomes, such as decreased ICP, hemodynamic control, and ideal pain control, were noted in many of the studies and within the literature. It appears that the use of ketamine does not increase ICP and may be just as efficacious as propofol for those presenting with TBI (Breindahl et al., 2021). USE OF KETAMINE VS. PROPOFOL IN ACUTE TRAUMATIC BRAIN INJURIES 3 Benefits of Ketamine Versus Propofol in Acute Traumatic Brain Injuries with Elevated Intracranial Pressure Annually there are over 5.48 million cases of TBIs, and they account for more than half of all trauma-related deaths (Dengler et al., 2022), and are the leading cause of disability and death in young adults in the United States (Hines & Marschall, 2017). During their hospitalization, it is incredibly important to maintain cerebral hemodynamics to provide better patient outcomes. These hemodynamics changes include hemodynamic parameters such as cerebral perfusion pressure (CPP), cerebral blood flow (CBF), intracranial pressure (ICP), and cerebral metabolic rate of oxygen (CMRO2). It is noted that periods of elevated ICP combined with hypotension leads to an increase in mortality and poorer outcomes for patients with a TBI (Dengler et al., 2022). A traumatic brain injury can result from both a closed head injury or a penetrating injury by foreign objects such as bullets. These injuries can then be further exacerbated by hypotension, defined as systolic blood pressure less than 90 mmHg or mean arterial blood pressure less than 65 mmHg (Hines & Marschall, 2017), and hypoxia. TBIs are categorized as either primary or secondary injuries. Primary injuries are directly related to trauma with a disruption in normal anatomy and physiology of the brain and are generally focal. Four categories of primary brain injuries are subdural hematoma, epidural hematoma, intraparenchymal hemorrhage, and nonfocal, diffuse neuronal injury from the disruption of axons of the central nervous system. The most common type of injury is an acute subdural hematoma, and this often warrants surgical intervention. This is the focus of this literature review as it is the most common injury seen and will be referred to as a TBI throughout the review. Acute subdural hematoma carries the highest risk of mortality. With this injury, there is an accumulation of blood from the veins between the USE OF KETAMINE VS. PROPOFOL IN ACUTE TRAUMATIC BRAIN INJURIES 4 skull and brain, which can lead to an increase in ICP, and compression of cerebral blood flow. Secondary injuries are from preventable situations such as systemic hypotension, hypoxia, hypercapnia, and hyperthermia. These secondary injuries have a further negative impact on patients who have primary head injuries and greatly increase the risk of morbidity and mortality. Thus, they should be treated aggressively and accordingly (Butterworth et al., 2022). The initial gold standard for assessing the seriousness of a neurological injury is the Glasgow Coma Scale (GCS). This scale assesses coma severity based on eye-opening responses, motor abilities, and verbal abilities (see Table 1). A GCS of less than eight is considered severe. Once determined that there is a significant injury it is important to measure ICP in patients who are unconscious and/or have a GCS <8. The gold standard for measuring ICP is an intraventricular catheter, which also allows for the drainage of CSF simultaneously. There is also the use of intraparenchymal, subdural, or epidural catheters. Intracranial pressure (ICP) refers to supratentorial cerebrospinal fluid pressure. A normal ICP is 5-15 mmHg in adults. This can be measured within the lateral ventricle or the subarachnoid space over the cerebral cortex (Nagelhout & Elisha, 2018). The Monro-Kelly doctrine states that the brain is not compressible and enclosed in the cranium, so any increase in intracranial volume will cause an increase in ICP (Nagelhout & Elisha, 2018). Further, the intracranial space is made up of four compartments: the brain, blood, intracellular water, and CSF. If any of these factors increase, there must be a decrease in the other factors to maintain a constant ICP. If compensatory mechanisms to decrease any of the other factors are not sufficient, ICP can rise. Elevated ICP is defined as pressures exceeding 20-25 mmHg. At this point, treatment is necessary to maintain appropriate cerebral hemodynamics and patient safety. USE OF KETAMINE VS. PROPOFOL IN ACUTE TRAUMATIC BRAIN INJURIES 5 Table 1 Glasgow Coma Scale (GCS)