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EVDs can be placed either in the operating room (OR) or at the bedside using local anesthesia.11,12 The OR provides a more sterile, controlled environment where acute complications can be efficiently managed. However, waiting for an OR room may delay treatment when emergent EVD is needed, and transporting critically ill patients leaves physicians without resources during transport. Although EVD placement in an ICU setting may increase the risk of severe infection, there are no conclusive data to determine how the environment of EVD placement affects the overall complication rate and outcome.11,13
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EVDs have traditionally been placed by neurosurgeons to ensure that the person who places the device can also manage procedure-associated complications, such as subdural or intracerebral hemorrhage. Recently, an increasing number of EVDs and ICP monitors have been placed by nonneurosurgeons, including neurointensivists, nurse practitioners, physician assistants, trauma surgeons, and general surgery residents.14 The impact of EVD placement by nonneurosurgeons on procedural success, complication rates, and outcomes is yet to be determined. Nevertheless, the increasing trend toward nonneurosurgeon EVD and ICP monitor placement, if proven equally safe and effective, may provide patients with more expeditious care in select environments.
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Although an EVD is thought to offer the most accurate ICP measurements, the surgeon may be unable to place an EVD in patients with collapsed ventricles, slit ventricles, or significant mass effect.5 In such cases, ICP can be monitored via placement of a fiberoptic parenchymal ICP bolt, which is a small fiberoptic cable passed through a burr hole and into the parenchymal edge, usually at the Kocher point. If an ICP bolt is placed and the team believes intracranial CSF volume is contributing to critically elevated ICP, a spinal drain can be placed in patients with communicating hydrocephalus. Just like an EVD, the spinal drain allows for lowering of ICP and treatment of hydrocephalus through CSF drainage. In effect, a parenchymal ICP bolt in conjunction with a spinal drain can serve the same functions as an EVD.15 Although intraparenchymal monitors are easily placed and can be disconnected during patient transport without the need for recalibration, they cannot accurately detect pressure alterations in deeper parts of the brain.15,16 The devices are also associated with mechanical failure, fragility, and monitor malfunction. Table 22-1 describes advantages and disadvantages of ICP-monitoring devices.
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Prior to receiving an external ventriculostomy, the 56-year-old patient presented above undergoes CT angiography, which reveals a 10 mm × 8 mm × 6 mm pericallosal aneurysm. See Figure 22-5.
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