Duet

Indications, Safety, and Warnings

It’s important for the healthcare provider to be familiar with all indications, warnings, and precautions for this device.

Indications

Draining and monitoring of cerebrospinal fluid (CSF) flow from the lateral ventricles or lumbar subarachnoid space is indicated in selected patients to:

• Reduce intracranial pressure (ICP), eg, pre-, intra-, or postoperative.
• Monitor CSF chemistry, cytology, and physiology.
• Provide temporary CSF drainage in patients with infected cerebrospinal fluid shunts.

Monitoring of intracranial pressure (ICP) is indicated in selected patients with:

• Severe head injury
• Subarachnoid hemorrhage graded III, IV, or V preoperatively
• Reyes syndrome or similar encephalopathies
• Hydrocephalus
• Intracranial hemorrhage
• Miscellaneous problems when drainage is to be used as a therapeutic maneuver.

Monitoring can also be used to evaluate the status pre- and postoperatively for space-occupying lesions.

Contraindications

Intracranial pressure monitoring with a ventricular or lumbar catheter is contraindicated in patients receiving anticoagulants or who are known to have a bleeding diathesis. The use of a ventricular catheter is contraindicated if scalp infection is present. A patient undergoing external drainage and monitoring must be kept under continuous, close supervision. The use of a ventricular or lumbar drainage catheter, or a Duet™ EDMS, is contraindicated where trained personnel are not available to supervise monitoring and drainage on a 24-hour-a-day basis.

The use of a lumbar catheter for drainage and monitoring of cerebrospinal fluid is not recommended for patients with non-communicating hydrocephalus; where lumbar puncture is contraindicated; in the presence of large intracranial mass lesions, tumors, hematomas, or cysts; in the presence of infections in the surrounding area which includes the skin, subcutaneous tissue, bone and the epidural space; and patients who have demonstrated blockage of cerebrospinal fluid to the subarachnoid space due to trauma, hematoma, fracture or tumor. The use of a lumbar catheter under these conditions for external drainage and monitoring is at the discretion of the physician.

Monitoring pressure from the lumbar subarachnoid space can be done only in instances where lumbar puncture does not pose a danger to the patient.

Warnings & Precautions

• Failure to appropriately adjust the rate of CSF outflow through the external drainage system may result in potentially serious injury to the patient.
• Patients undergoing external drainage and/or intracranial pressure monitoring must be kept under constant supervision in an intensive care unit staffed with trained personnel familiar with the use of intracranial and lumbar pressure monitoring techniques.
• Improper vigilance or improper drainage system setup can lead to overdrainage or underdrainage and potentially serious injury to the patient. Intracranial and lumbar pressure monitoring has been associated with intracranial infection, meningitis and ventriculitis. This hazard has been quoted at less than 1% to more than 5%. The risk of infection is probably influenced both by the number of times a system is opened and by the duration of the monitoring. Prolonged steroid therapy can also increase the risk of infection.
• It is possible that the puncture of the ventricle or the opening of the dura will result in an intracranial hemorrhage.
• It is possible that if too much CSF is removed from the ventricles, either during a drainage procedure or when the ventricle is first punctured, the ventricle may collapse and occlude the catheter.
• It is possible that the monitoring system may give a false pressure reading either due to a pressure line becoming clogged or kinked or from an air bubble lodged in the system. An incorrect pressure reading may lead to the wrong therapy being given to the patient. The irrigation of the catheter or the performance of a Volume Pressure Relationship (VPR) study may induce pressure waves in the patient. For this reason, irrigation or VPR studies should be done only by, or on the order of, a physician.
• In order to minimize the possibility of infection, meningitis or ventriculitis, several steps should be observed. First, the injection sites should always be cleaned with alcohol and the alcohol allowed to dry before a needle is inserted into them. Second, sterile technique should be observed in setting up the system and in the placement of the catheter. Third, subgaleal tunneling of the ventricular catheter should be approximately one to two inches.
• In order to avoid possible cracking of the Luer connectors after cleaning with alcohol, allow to air dry completely prior to connecting the system.
• Leakage from the system, which can result from damaged system components or improper use or handling, can potentially result in overdrainage, the need to replace the drainage system and/or other complications to the patient.
• In order to ensure against ventricular collapse and the possible consequence of tentorial herniation, always perform a drainage maneuver against a positive pressure head on the order of 20 cm H2O or 15 mm Hg. In addition, when the ventricle or lumbar subarachnoid space is first punctured during the insertion of the catheter, care should be taken so as little CSF as possible is lost.
• A double suture tie with silk suture should be used to secure the ventricular or lumbar catheter to the connection fitting. Check to ensure that the connection is tight prior to use.
• Whenever irrigation of the catheter or the performance of the VPR is decided upon, great care must be used so that pressure waves are not initiated. Only a small volume of saline should ever be injected into the ventricular system, and this only done by, or on the order of, a physician. In general, in monitoring intracranial pressure, one should always be aware of the waveform on the oscilloscope. If the waveform begins to dampen out, it is important that the entire monitoring system be examined. Ensure that the line to the patient is not kinked and that all air bubbles or blood or other debris are removed from the system.
• Ascertain that the transducer is on the same level as the patient’s ventricular system to ensure the proper reference level in the manometer tube for use in calibration procedures. Pressure monitoring with the manometer may result in overdrainage of the ventricles.

Complications

• Infections, particularly meningitis, ventriculitis, and wound infections
• Overdrainage, leading to:
  • Intracranial hemorrhage
  • Permanent neurological deficit
• Frequent punctures of the brain to insert the ventricular catheter can predispose to intracerebral hemorrhage and edema leading to a further rise in Intracranial Pressure (ICP).
• Poor recording of ICP will result if the catheter, patient line or other components of the monitoring system become clogged with blood clots, brain tissue fragments, or fibrinous debris.
• Ventricular wall collapse, in small patients, resulting in obstruction of the catheter and predisposing to tentorial herniation. It is therefore important to avoid excessive release of CSF before the system catheter is attached to the patient line.
• Limiting the duration of monitoring from a single site to less than five days will reduce the infection rate.

If monitoring must continue past five days, consider inserting a new catheter at a fresh site and changing the entire system.

Important Safety Information

Attention Consumers!
This therapy is not for everyone. Please consult your physician. A prescription is required.

Attention Physicians!
For further information, please contact your Medtronic NT sales representative.

Caution: Swedish law restricts this device to be ordered by, and sold to, a physician or medical institution only. Refer to product package insert for instructions, warnings, precautions and complications.