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Hypothermia Guideline for the Treatment of Refractory ICP

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Guideline of Care

Increased intracranial pressure (ICP) has been associated with poor outcomes in brain-injured patients, including those with hepatic encephalopathy. Hypothermia may provide benefit in controlling ICP; however, this has not always translated to improved patient outcomes. Its use for ICP control is considered a Level III recommendation in the Traumatic Brain Injury guidelines published by the Brain Trauma Foundation. Nevertheless, hypothermia is often considered in the management of refractory ICP.

Patient Selection

Patients who have been shown to benefit from induced hypothermia for elevated ICP include:

  1. Traumatic brain injury (TBI).
  2. Stroke.
  3. Hepatic Encephalopathy.

Relative Exclusion Criteria

Patients in whom hypothermia may come with increased risk include those with:

  1. Recent major surgery within 14 days - hypothermia may increase the risk of infection and bleeding.
  2. Systemic infection/sepsis- hypothermia inhibits immune function and is associated with an increased risk of infection.
  3. Patients with active ongoing bleeding - hypothermia may impair the clotting system.

Preparation

Cooling should be instituted as early as possible when ICP is felt to be refractory to conventional measures.

  1. A continuous temperature monitor will aid in the cooling process and prevents "overcooling."
    • A bladder temperature probe is used to monitor the temperature.
    • Pulmonary artery temperature probe may be used, if available.
  2. It is recommended that a secondary temperature device (Exergen) be used to also monitor temperature. The bladder probe is only accurate when there is adequate urine output; therefore, an alternative to the bladder temperature probe is required in the setting of oliguria. This alternative temperature probe can be any core temperature monitor that is compatible with the Arctic Sun console.

Methods

  1. Cold saline chilled to 4º degrees Celsius has been used to lower temperature during hypothermic therapy. It may also be useful in "breaking" high fever in neurologically impaired patients (Exclusions: Patients who may not tolerate large amounts of fluid over 30 minutes due to cardiac insufficiency).
    1. Materials Needed:
      1. Foley catheter with temperature measurement port.
      2. Temperature measurement cable and Marquette monitor port.
      3. Cooled Normal Saline at 3 degrees Celsius from medication refrigerator.
      4. Patient weight determines the amount of saline delivered (Calculation is 30cc of saline per kg).
      5. Peripheral IV access recommended. Cold Saline should be delivered through a peripheral line. Subclavian and internal jugular infusions have been known to cause lethal arrhythmia. Delivery by a femoral venous line may be acceptable if no peripheral access is available.
    2. Procedure:
      1. Place catheter and record both Exergen and bladder temperature on the flow sheet.
      2. Set up first liter of Normal Saline on large bore tubing and into a pressure bag for delivery into a peripheral I.V. Total cold normal saline fluid volume is calculated as 30cc/kg, run over 30-45 minutes.
      3. Cold Saline should be given via a peripheral line.
      4. Record temperature with Exergen and bladder catheter every 10 minutes.
  2. Cooling with an external cooling pad device:
    1. Eligibility confirmed and materials gathered.
    2. Place continuous temperature device and place cooling pad on patient.
    3. After applying pads, set target goal. Mild hypothermia [35ºC (95ºF)-34ºC(93.2ºF)].
    4. Assess for shivering and medicate to cease shivering if needed.
    5. These pads may be used with external pacing pads. Place the external pacing pads on the chest and cover with Arctic sun pads.
    6. Refer to re-warming for strategies to re-warm.

Supportive Therapy

  1. Monitor ICP. Continue other medical therapies that support treatment of increased ICP.
  2. Keep CPP > 60mmHg. Often BP remains elevated during hypothermia as a result of peripheral vasoconstriction. Hypotension is a particular concern during the warming phase due to vasodilation, and thus controlled slow re-warming is necessary.
  3. Monitor patient for arrhythmias (most commonly bradycardia) associated with hypothermia. An Osbourne or camel wave may be present when cooling, and does not require specific therapy. If significant dysrhythmias, hemodynamic instability or bleeding develop, then cooling should be discontinued, and the patient actively re-warmed. Rebound increased ICP and/or hypotension may occur if patient is rewarmed too quickly.
  4. Blood work requirements include electrolyte panel, glucose, CBC, and blood cultures at 12 hours and 24 hours. Hypothermia commonly causes hypokalemia, which may be exacerbated by insulin administration. Conversely, when patients are re-warmed, potassium exits cells, and hyperkalemia may occur. Both hypo- and hyperkalemia should be treated when they occur. Unexplained hyperglycemia and increases in serum amylase and lipase have been observed during hypothermic therapy.
  5. All ABG measurements must be analyzed at the patient's actual body temperature. For CO2 goal discuss with the treating physician.
  6. Assess skin every 6 hours by gently peeling back the external cooling pads. (Arctic Sun)
  7. Always use a secondary temperature monitoring device when using any cooling device. Record the patient temp on the device, the secondary temp source (Exergen) and the water temperature of the Arctic Sun. The water temp will help to determine the work of the machine in trying to keep the patient at target.

Shiver Management

Assessment and management of shivering is critical to the success of any temperature management strategy. Shivering increases the metabolic rate and heat production which is detrimental to ICP management and counteracts any attempts to cool the patient. Also, microshivering or non-detectable shivering should be suspected if patient does not reach cooling goal with 2 hours.

No Shivering:

  • Standing acetaminophen

Shivering < 5 min:

  • Forced air convection warmer (Bair Hugger)
  • Meperidine intermittent IV push 12.5-50 mg up to 3-4 times daily. Not to be used in patients with documented renal insufficiency (serum creatinine ≥ 1.5). Contraindicated with the concomitant use of monoamine oxidase inhihibitors MAOI within the past 2 weeks.
  • Buspirone 5 mg ORALLY 2-3 times a day OR 7.5 mg ORALLY twice a day; may increase the dosage by 5 mg/day every 2-3 days as needed (usual dose 20-30 mg/day 2-3 divided doses, MAX dose 60 mg/day)

Shivering for > 5 min:

  • When above interventions have not worked, then convert to meperidine infusion 25-50 mg/hr, or propofol 10-300 mg/hr.

Breakthrough Shivering:

  • Consider infusion of dexmedetomidine 1 mcg/kg over 10 min*. Maintenance infusion dose range is 0.2-0.7 mcg/kg/hr.
  • If dexmedetomidine is ineffective or unavailable, consider magnesium sulfate drip 1 g/hr for goal Mg level of 3-4.5 mmol/L, or dantrolene*.

Refractory Shivering:

  • Cisatricurium or vecuronium (please refer to hypothermia after cardiac arrest guideline for dosing)

*May be used only with pharmacy approval in specific units. Please contact the Neuro ICU staff regarding its use in specific instances (726-8071).

Re-warming

The re-warming phase is the most critical as re-warming too quickly can lead to rebound elevated ICP, poor patient outcomes and even death. Re-warming should be done very slowly over a period of at least 24 hours. Peripheral beds, which were once constricted, start to dilate. This shift sometimes causes hypotension. Monitor for rebound elevated ICP.

  1. Monitor patient for hypotension related to re-warming, secondary to vasodilation.
  2. Monitor patient for hyperkalemia during re-warming as potassium moves from intracellular to extra cellular compartment.
  3. Monitor for hypoglycemia as intrinsic insulin stores increase.
  4. The goal after re-warming is normothermia 37 ºC(i.e. avoidance of hyperthermia).
  5. Normothemia should be maintained aggressively for at least 24 hours once reached. This will ensure the management of fever which may cause an increased risk of cerebral edema.

Controlled Re-warming using an external vest device (Arctic Sun):

The device can be programmed for controlled re-warming over a period of at least 24 hours. Dial in the desired warming rate on the machine. The device should be programmed to maintain a target temp of 37°C (98.6°F) at a rate of no more than 0.5 degrees per hour.

References

Brain Trauma Foundation; American Association of Neurological Surgeons; Congress of Neurological Surgeons; Joint Section on Neurotrauma and Critical Care, AANS/CNS. Guidelines for the management of sever traumatic brain injury III. Prophylactic hypothermia. Journal of Neurotrauma. 2007; 24: S21-25.

Bajatia,N,et al. (2006) Rapid Infusion of Cold Saline as an adjunct treatment of fever in head injured patients. Neurology, 66 1739- 1741.

Jalan, R., et al. (2003). Moderate hypothermia prevents cerebral hyperemia and increase in intracranial pressure in patients undergoing liver transplantation for acute liver failure. Transplantation. 75 (12) p.2034-2039

Polderman, K.H. (2008). Induced hypothermia and fever control for prevention and treatment of neurological injuries. Lancet. 371 p.1955-1969.

Stravitz, T.R., et al. (2007). Intensive care of patients with acute liver failure: Recommendations of the U.S. acute liver failure study group. Critical Care Medicine. 35 (11) p. 2498-2508.

Takashi, T., et al. (2009). Effect of 35°C hypothermia on intracranial pressure and clinical outcome in patients with severe traumatic brain injury. The Journal of TRAUMA. 66 (1) p. 166-173.

Authoring Information

Reviewed/Approved by: Taylor Kimberly, M.D., Ph.D and Guanci, Mary M, MSN, RN, CNRN

Last updated: 09/06/10

Authors: David M. Greer, M.D., Guanci, Mary M, MSN, RN, CNRN and Gayle Montoya, MSN, R.N.

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