Intracranial pressure monitoring

Emergent, Controlled Lumbar Drainage for Intracranial Pressure Monitoring During Orthotopic Liver Transplantation

Authors: C. Joseph Bacani, W. D. Freeman, Rachel A. Di Trapani, Juan C. Canabal, Lisa Arasi, Timothy Shine and Darrin L. Willingham.

Background:  Measurement of intracranial pressure (ICP) is recommended in comatose acute liver failure (ALF) patients due to risk of rapid global cerebral edema. External ventricular drains (EVD) can be placed to drain cerebrospinal fluid and monitor ICP simultaneously although this remains controversial in the neurosurgical community given the risk of hemorrhagic complications. We describe a patient with ALF and global cerebral edema whose EVD failed immediately before orthotopic liver transplantation (OLT) in which a lumbar drain (LD) was used temporarily to monitor ICP.
Methods:  We describe a 36 year old patient with ALF and brain edema from acetaminophen overdose who had an EVD placed for ICP monitoring and management. The EVD failed repeatedly (i.e., lost CSF drainage and ICP waveform) despite several saline irrigations and three doses intraventricular tissue plasminogen activator (1 mg) in the hours that immediately preceded her planned emergency OLT. An LD was placed emergently and controlled cerebrospinal fluid (CSF) drainage and ICP measurement was performed by setting the LD at 20 mmHg and leveling at the ear level (foramen of Monro). The LD was removed once the EVD flow was re-established post-OLT.
Results: The EVD and LD ICP measurements were reported to be the same just prior to removing the LD.
Conclusions: Controlled CSF drainage using a lumbar drain can be used to monitor ICP when leveled at the foramen of Monro if EVD failure occurs perioperatively. The LD can temporarily guide ICP management until the EVD flow can be re-established after OLT.

Moderate hypothermia with intracranial pressure monitoring as a therapeutic paradigm for the management of acute liver failure: a systematic review

Authors: Dmello D, Cruz-Flores S, Matuschak GM.

OBJECTIVE: To systematically review the literature and present data on the safety and efficacy of induced moderate hypothermia combined with ICP monitoring in critically ill patients with acute liver failure.

DESIGN: We conducted a retrospective observational search of MEDLINE database using both OVID and PubMed with the following MeSH terms, "Hypothermia, Induced," "Brain Edema," "Intracranial Hypertension" (ICH), "Liver failure, Acute" and "Liver Failure, Fulminant." We limited our search to case series involving at least three human subjects and all other clinical trials. Baseline ICP, cerebral perfusion pressure (CPP) and cerebral blood flow (CBF) as well as the response of these variables to hypothermia were recorded when available. Additional clinical and demographic data were also recorded.

RESULTS: Five case series were identified. Pre-existing coagulopathy from liver failure was reversed by various modalities in all studies prior to insertion of ICP monitors. Induction of moderate hypothermia combined with ICP monitoring consistently improved ICP, CPP and CBF in four trials; one trial demonstrated the feasibility and effectiveness of moderate induced hypothermia as part of a protocolized strategy for the management of ICH.

CONCLUSIONS: Limited data exist concerning the safety and efficacy of moderate hypothermia and ICP monitoring for the treatment of ICH in acute liver failure. The available evidence shows that induction of moderate hypothermia in this clinical setting is feasible and possibly efficacious. Well-designed prospective clinical trials are warranted in this challenging context, given the potential of providing a bridge to liver transplantation or even clinical recovery.

The baseline pressure of intracranial pressure (ICP) sensors can be altered by electrostatic discharges

Authors: Eide PK, Bakken A.

BACKGROUND: The monitoring of intracranial pressure (ICP) has a crucial role in the surveillance of patients with brain injury. During long-term monitoring of ICP, we have seen spontaneous shifts in baseline pressure (ICP sensor zero point), which are of technical and not physiological origin. The aim of the present study was to explore whether or not baseline pressures of ICP sensors can be affected by electrostatics discharges (ESD's), when ESD's are delivered at clinically relevant magnitudes.

METHODS: We performed bench-testing of a set of commercial ICP sensors. In our experimental setup, the ICP sensor was placed in a container with 0.9% NaCl solution. A test person was charged 0.5 - 10 kV, and then delivered ESD's to the sensor by touching a metal rod that was located in the container. The continuous pressure signals were recorded continuously before/after the ESD's, and the pressure readings were stored digitally using a computerized system

RESULTS: A total of 57 sensors were tested, including 25 Codman ICP sensors and 32 Raumedic sensors. When charging the test person in the range 0.5-10 kV, typically ESD's in the range 0.5 - 5 kV peak pulse were delivered to the ICP sensor. Alterations in baseline pressure >2 mmHg was seen in 24 of 25 (96%) Codman sensors and in 17 of 32 (53%) Raumedic sensors. Lasting changes in baseline pressure >10 mmHg that in the clinical setting would affect patient management, were seen frequently for both sensor types. The changes in baseline pressure were either characterized by sudden shifts or gradual drifts in baseline pressure.

CONCLUSIONS: The baseline pressures of commercial solid ICP sensors can be altered by ESD's at discharge magnitudes that are clinically relevant. Shifts in baseline pressure change the ICP levels visualised to the physician on the monitor screen, and thereby reveal wrong ICP values, which likely represent a severe risk to the patient.

Intracranial pressure monitoring

Authors: R. Ravi a and R. J. Morgan b

Maintaining adequate cerebral perfusion is the primary goal of management of patients with traumatic brain injury and intracranial pressure is one of the major factors affecting cerebral blood flow. Intracranial pressure measurement is necessary to confirm or exclude intracranial hypertension and to determine cerebral perfusion pressure. It also helps guide therapy in head injury patients. There is a substantial body of evidence to support the use of intracranial pressure monitoring and it is now a central part of the critical care management of the severely brain injured patient. This is a review of intracranial pressure monitoring with specific reference to traumatic brain injury. A brief description of the physiology of cerebral blood flow and intracranial pressure is given followed by the principles of measurement, indications, techniques and problems associated with intracranial pressure monitoring.

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