External Ventricular Drain Related Complications-Whether Continuous CSF Drainage Via Ommaya Reservoir is the Answer?
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.284354
Source of Support: None, Conflict of Interest: None
Keywords: Continuous EVD drainage, EVD blockage, EVD complications, EVD infection, external ventricular drainageOmmaya reservoir can be used for all cases requiring external CSF drainage to reduce EVD related complications.Key Message: Ommaya reservoir can be used for all cases requiring external CSF drainage to reduce EVD related complications.
External ventricular drainage (EVD) is one of the commonest procedures in neurosurgical practice. EVD is required for Cerebrospinal fluid (CSF) drainage externally in multiple conditions. EVD is associated with several complications like catheter blockage, catheter dislodgement, and CSF infection. CSF infection after EVD in particular can be a nightmare for the surgeon and can significantly prolong the hospital stay of patient and adversely impact patient outcomes. Over the years, many modifications of standard EVD have been attempted to reduce complications associated with the procedures. In this article, we describe our institutional technique of EVD and its results.
Brainlab Vector-vision with intra operative computerized tomography (iCT) (Brainlab AG, Feldkirchen, Germany).
All Ommaya reservoirs were inserted in Operation theatres under sterile condition. Neuro-navigation was used in patients with small or distorted ventricles.
A small 3 cm semi-circular incision is made over the pre-coronal area and scalp flap is retracted using a self-retaining retractor. 14 mm burr hole is made and bone edges waxed. Duramater is coagulated and a small opening is made. Piamater is also coagulated with bipolar cautery forceps. Ventricular catheter is inserted towards ipsilateral medial canthus in medio-lateral and towards ipsilateral tragus in antero-posterior direction. Once the ventricle is hit and CSF flow is confirmed, ventricular catheter is connected with 18 mm Ommaya reservoir chamber and the connection is secured with a non-absorbable suture. Scalp is closed in a standard two layered fashion. The Ommaya reservoir is not directly under the line of incision. External assembly consists of a scalp vein set, with a non-coring needle. The needle is inserted in a zig-zag fashion percutaneously to puncture the Ommaya reservoir. [Figure 1] The flexible end of the scalp vein set is connected to the CSF reservoir bag with a 100 cm tube. A three way is used to connect the scalp vein set with the tubing, to facilitate repeated CSF samplings. The entire external assembly was changed, including the needle for entry into the reservoir, whenever the reservoir bag reached its full capacity with a fresh point of entry through the scalp.
All patients that required CSF diversion externally were included in the study. Patients that required continuous CSF drainage were only included in the study and those on intermittent CSF drainage were excluded from the study. Patients, who had an EVD inserted in a normal ventricular catheter fashion through twist drill, were converted to Ommaya reservoir assembly method in our hospital.
Patients, who had Ommaya reservoir placement for intrathecal chemotherapy or tumor cyst drainage were not included in the study. New infection was defined as a positive CSF culture in primarily non-infected patients, or growth of a secondary pathogen in primarily infected patients.
Prophylactic antibiotics and CSF surveillance
Prophylactic antibiotics were used during the course of the CSF drainage. CSF was screened only at the time of change of the external assembly.
The data was collected retrospectively from January 2014 to June 2017. A total of 59 patients fit into the criteria for inclusion. Forty (67.79%) patients were male and 19 (32.20%) patients were female. Age of patients varied from 1 month to 71 years. 48 (77.96%) patients had non-infected CSF at time of starting drainage for various indications including subarachnoid hemorrhage, intra-ventricular hemorrhage, or tumor associated hydrocephalus. Thirteen (22.03%) patients required external CSF drainage for infected CSF [Table 1]. The primary infective agent was MRSA in 3 patients, Pseudomonas in 3 patients, Acinetobacter in 2 patients, Klebsiella in 2 patients and Staphylococcus epidermidis in one patient.
The study period had a total of 793 CSF drainage days (Range 3-64 days) with an average of 13.4 days per patient. Twenty three (38.9%) patients required drainage for less than or equal to 7 days, while 36 (61.01%) patients required drainage for more than 7 days. Mean duration for CSF drainage was highest for patients with infected CSF primarily.
Two patients from 48 (4.16%) developed infection in primarily non-infected CSF and one patient from 13(7.69%) developed a secondary or new infection. The cumulative rate of new infection was 5.08%.
No blockage of ventricular catheter was seen. Ventricular end was changed electively in two patients (3.38%) with infected CSF for faster resolution of CSF infection. Fresh Ommaya hardware was put in opposite ventricular system.
No accidental catheter dislodgement was seen in the study period. The common disconnection point in the external assembly is the entry site of the needle into the Ommaya chamber. The disconnection rate is 1 per 6 drainage days.
EVD is a very versatile procedure. EVD is done for a variety of indications in routine and emergency neurosurgical practice as a lifesaving procedure. However, it is associated with an unacceptably high incidence of complications. The commonest and most dreaded complication is infection. The infection rate related to EVD have been described from 0-45%. Other non-infective complications include those associated with catheter maintenance like blockage, and dislodgement.
Several techniques have been described to reduce the incidence of infection associated with EVD. The use of antibiotic- and silver impregnated catheter, reducing frequency of CSF samplings, use of tunneled catheters, prophylactic antibiotics, or following a set of measures in a protocol based fashion in intensive care unit (ICU) have been described in literature to reduce such infections. CSF leak for more than 24 hours is another possible risk factor for increase in infection. All these techniques have their own benefits and pitfalls, and discussing all these individually is beyond the scope of this article. The infection rate for primarily non-infected CSF, in our study was 4.16%, and we believe that it can be brought down further as we gain more experience with this technique. The secondary infection rate of 9.09%, seen in patients with already infected CSF may be because of use of intrathecal antibiotics through the EVD, which require repeated openings of the closed drainage system.
There are certain non-infective complications associated with EVD, like ventricular catheter dislodgement or catheter pullouts, catheter blockage, catheter breakage, CSF leak from skin entry site The technique that we have described does not require any special catheters. It can be done under local anesthesia as it does not require long tunneling which may need general anesthesia or deep sedation. EVD using this method can be maintained even in non-neurosurgical ICU where para-medical staff is not well trained in handling patients with EVD. It is not uncommon for ventricular catheters to get dislodged or get pulled out while shifting or positioning the patient. This is preventable with our technique as only the external assembly will get disrupted during such inadvertent events, but the ventricular catheter remains in place.
One frequent point of disconnection in this whole assembly is the junction of external and internal assembly, that is the needle of scalp vein set gets dislodged from the Ommaya reservoir chamber. This can also be reduced with the help of a stay suture to secure the needle to the skin.
In case of disconnection, we recommend changing the entire external assembly with a fresh scalp vein set to puncture the Ommaya chamber using a fresh entry point through the skin and taking a zigzag path through the layers of the scalp. Taking a zigzag path through the skin to enter into the reservoir prevents CSF leak through the puncture site, and seals off the tract once the needle is removed.
Keeping dressing over the EVD insertion site is another challenge as the hair growth and secretions prevent a tight occlusive adhesive dressing over the scalp. In our technique, besides the external dressing, the skin acts as a natural dressing and as a strong natural barrier to ingress of micro-organisms. The epitheliazation of surgical wounds happens within 24 hours, and it sort of prevents entry of micro-organisms from outside. Our technique provides a very effective and natural dressing, thereby providing a unique way to reduce infection rate.
After insertion, EVD monitoring, maintenance and troubleshooting has essentially become more of a nursing responsibility. Therefore, the EVD maintenance requirements needs to kept simple and technically less challenging. After the reservoir placement, the technique described in this article is simple enough, and can be performed by nurses.
It has been widely accepted that the CSF sampling from the EVD assembly should be kept to a minimum and there should be as minimum as possible manipulation of the EVD. We follow the same principles and avoid opening of the closed EVD system and empirical CSF samplings. We change the entire external assembly simultaneously, whenever there is a need to change the system. The CSF collection bag is 1000 ml capacity and we do not drain the bag on a daily basis. Once the bag fills up, instead of emptying the bag, we change the entire external assembly from the scalp vein set to the bag. The new needle makes a fresh point of entry into the reservoir as described already.
Even though all procedures in our study were done inside an Operating room, the procedure can also be done bedside under local anesthesia if the need arises. To put an Ommaya reservoir, we need a slightly larger opening than a conventional twist drill. This can be done conveniently by making a burr hole bed side.
In the operating room, navigation can be used for non-dilated or distorted ventricles. Navigation theoretically reduces the risk of malpositioning the ventricular catheter even when studies do not prove it to be better than free hand techniques.
The smaller caliber of the needle used for entry into the reservoir will cause slight increase in the resistance to the CSF outflow as compared to a larger caliber ventriculostomy catheter in EVD. In our study, we did not encounter any difficulties in controlling the intra-cranial pressure (ICP) or rate of flow of CSF. In fact, we believe that this should help in maintaining a continuous and steady flow of CSF by preventing CSF over drainage and complete collapse of the ventricle.
Ommaya reservoir is removed in all patients with infected CSF, after resolution of infection. In patients who require a shunt, the Ommaya is removed at the time of shunt surgery.
Drawbacks of this study include a single institutional data, short study period, smaller patient size, lack of a control and lack of prospective data. Although based on our data, this technique looks promising, but needs further studies to confirm our findings.
EVD using a CSF reservoir placed under the scalp is a safe and effective method of CSF drainage. It helps reduce the rate of CSF infection, along with non-infective complications associated with maintenance of EVD. This technique of EVD insertion can be included in the bundle of EVD management practices at different institutes, to improve upon the existing results.
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Conflicts of interest
There are no conflicts of interest.