Intracranial Pressure Monitors
Margaret Riordan, MD , Lawrence Chin, MD*
About 50% of patients with severe traumatic brain injury and abnormal computed tomography (CT) scans have elevated intracranial pressure; thus, the most recent set of
Brain Trauma Foundation guidelines recommends ICP monitor placement in any patient with a severe head injury who has an abnormal CT scan. These patients are defined as having a
Glasgow Coma Scale score of 3 to 8 after adequate cardiopulmonary resuscitation. Abnormal CT scan findings include hematomas, contusions, and generalized edema. Additionally, there is grade 3 evidence for ICP monitor insertion in intraventricular space.
The external drainage catheter is a cerebrospinal fluid diversion device that also measures intracranial pressure. The catheter tubing is translucent with depth markings and contains a radiopaque barium sulfite strip. ICP readings are based on a fluid-filled transduction system that transmits changes in intracranial pressure through a saline-filled tube to a diaphragm on a strain gauge transducer.6,13,14 This monitor must be leveled with the Foreman of Monro (approximately the level of the external auditory canal) after insertion and should be zero balanced daily. The level of the drain can be adjusted to allow more or less CSF drainage. These monitors can be left in place for several days, but most manufacturers recommend replacing the fiberoptic monitors after about 5 days to ensure accurate ICP readings. ICP monitors can be removed easily at ith sutures to
Department of Neurosurgery, SUNY-Upstate, 750 Adams Street,
Syracuse, NY 13210, USA
KEYWORDS te se th ntr re s.theclinics.comthe bedside, and the entry point is closed w prevent CSF leaks. * Corresponding author.
E-mail address: email@example.com
Atlas Oral Maxillofacial Surg Clin N Am- (2015) -e1061-3315/15/$ - see front matter ª 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.cxom.2015.05.003 oralmaxsurgeryatlatoring leads to either medical or surgical intervention resulting in decreased mortality.7,8pressure. Several studies have shown that close ICP monis, whereas the EVD is not accurate unless it is located in theIntroduction
The first documented external ventriculostomy (EVD) for elevated intracranial pressure (ICP) was performed in 1744 using a wick to drain cerebrospinal fluid (CSF) after a ventricular puncture, but it was not until 1881 that the first sterile EVD was performed. By the 1950s, the overall drainage system had not significantly changed. The most common early use for ICP monitoring andCSFdrainagewasReye’s syndrome. EVDs arenow frequently used in trauma patients with severe head injuries, patients with obstructive hydrocephalus after subarachnoid hemorrhage, large strokes, or other large structural lesions.1e3
ICP monitoring is considered a mainstay for the management of acute brain injury. The brain is enclosed by the skull and is a fixed container. Thus, based on the Monro-Kellie doctrine, any addition to this space, such as a hematoma, will increase ICP. Normal intracranial pressure is less than 20 to 25 mm Hg, and sustained pressures from 20 to 30 mm Hg are associated with increased mortality.4 Most neurocritical care specialists and trauma surgeons base their medical management on maintaining cerebral perfusion pressure, which is calculated by subtracting the ICP from the mean arterial 5,6 Traumatic brain injury Intracranial pressure monitor Ex
KEY POINTS Intracranial pressure monitors are indicated in patients with between 3 and 8 or for acute hydrocephalus. These monitors can easily be inserted at the bedside, and pressure that can guide management and treatment plans. There are few major complications after placement of i monitor, hemorrhage, and inaccurate intracranial pressurepatients with a normal CT scan if the patient has at least 2 of the following criteria: (1) age greater than 40 years, (2) motor posturing, and (3) systolic blood pressure less than 90 mm Hg.6,9e12
ICPmonitoringandCSFdrainageare also commonlyused in the setting of acute hydrocephalus, which may be caused by subarachnoid hemorrhage, intraventricular hemorrhage, or mass lesions. A ventriculostomy insertion allows for ICPmonitoring and
CSFdrainage, thusalleviating intracranial pressure.Furthermore,
EVDs may be useful in patients with meningitis who have hydrocephalus both for CSF drainage and antibiotic delivery.1,2
There are 2 basic types of ICP monitors: those that provide
ICP data only (commonly referred to as a bolt) and those that allow for concurrent drainage of cerebrospinal fluid while measuring ICP (external ventriculostomy or intraventricular catheter). Monitors that drain CSF detect changes in pressure based on flow through a fluid-filled system and are most accurate when the system is closed to drainage. The combination of a ventriculostomy with a closed drainage system is also known as an external ventricular drain or EVD. Bolts use fiberoptic technology that allows for continuous ICP monitoring without CSF drainage. The fiberoptic type of catheter can be placed in the subdural space or in the brain parenchyma, rnal ventriculostomy Cerebrospinal fluid vere traumatic brain injury and a Glasgow Coma Scale score ese devices provide accurate measurements of intracranial acranial pressure monitors, including infection, misplaced cording over time. marked at Kocher’s point to help guide the trajectory of the 16 2 Riordan & Chincatheter once the patient is draped.
Surgical procedure 1. After the incision has been planned as described above, the skin is prepared around the proposed incision site. The skin preparation should also incorporate 2 to 3 cm around the incision to allow a sterile exit site for the catheter. 2. The surgical site is then sterilely draped. 3. The incision is injected with a local anesthetic such as 1% lidocaine. Note this step should be skipped if there is concern for a dural breach, as lidocaine can potentiate seizure activity. 4. The incision is then opened down the skull with a number 10 blade scalpel.Surgical technique