Critical Care Medicine-Neurologic Disorders>>>>>Increased Intracranial Pressure
Question 4#

A 32-year-old female with chronic alcoholism and cirrhosis was brought to the emergency department following a night of binge drinking. She was found unresponsive at home and EMS was called. On arrival to the emergency department she was intubated for airway protection. She did not require sedation for intubation and is not currently on any sedation. A head CT was completed and demonstrated diffuse cerebral edema with effacement of the sulci and ventricular system. Her lab results were remarkable for an elevation in AST and ALT (2000, 1000 units/L respectively), total bilirubin 5.6 mg/dL, and ammonia 3642 µm/L. Her examination remains poor, with only extensor posturing to motor stimulation. Her pupils are 5 mm and sluggishly reactive to light.

Given the findings on head CT what is the next best step in management?

a. Hyperventilate the patient with goal pCO2 20 mm Hg
b. Start sedation with a midazolam infusion at 1 mg/h
c. Placement of an intraparenchymal monitor for intracranial pressure monitoring and guidance of therapy
d. Infusion of mannitol at 1 g/kg and if needed repeat every 6 hours
e. Emergent liver transplantation

Correct Answer is D

Comment:

Correct Answer: D

Fulminant liver failure is frequently associated with worsening cerebral edema and elevation in ICP. The detoxification of high ammonia levels to glutamine in astrocytes results in increased intracellular osmolality and cerebral edema. Given the extremely high mortality rate associated with the development of cerebral edema, it is prudent to aggressively manage this pathology. There is a step-wise approach in the management of intracranial hypertension which starts with head of bed elevation, and securing airways should always take priority and starting the patient on sedation could help controlling ICP. In liver failure patients, midazolam, which through multiple CYP pathways, will accumulate and cause complications. Propofol might be a safer option; however, it is thoroughly studied in this cohort of patients. 

The use of hyperosmolar therapy (mannitol and hypertonic saline) for increased ICP in acute liver failure is extrapolated from its use in head trauma. Smaller studies showed that hypertonic saline helps reducing ICP when was used in patients with grade III and IV hepatic encephalopathy and mannitol helps reducing cerebral edema and improves survival in patients with fulminant hepatic failure.

Overall, the common practice is to place an intracranial monitor to best manage these patients. However, given the possibly underlying coagulopathy in these patients, hemorrhages related to ICP monitor placement can be catastrophic and may add to the overall mortality. Smaller studies showed that epidural catheters have lower hemorrhage rates and precision relative to subdural bolts and intraparenchymal catheters.

Regarding other ICP management options, hyperventilation is a temporizing measure which can result in lowered ICP but prolonged hyperventilation carries a serious risk of significant reduction in cerebral blood flow (CBF) and cerebral ischemia.

Although transplantation can be potentially considered, treating intracranial hypertension at this point takes priority.

References:

  1. Cordoba J, Blei AT. Cerebral edema and intracranial pressure monitoring. Liver Transplant Surg. 1995;1:187-194.
  2. Conn HO. Hyperammonemia and intracranial hypertension: lying in wait for patients with hepatic disorders. Am J Gasteroenterol. 2000;95:814-816.
  3. Rossi S, Buzzi F, Paparella A, et al. Complications and safety associated with ICP monitoring: a study of 542 patients. Acta Neurochir Suppl. 1998;71:91-93.
  4. Karvellas CJ, Fix OK, Battenhouse H, et al. Outcomes and complications of intracranial pressure monitoring in acute liver failure: a retrospective cohort study. Crit Care Med. 2014;42:1157-1167.
  5. Amarapurkar DN. Prescribing medications in patients with decompensated liver cirrhosis. Int J of Hepatology. 2011;2011:5.