Family of measures for this quality improvement initiative

We sought to evaluate our adherence to a new institutional protocol to manage PHVD, with early placement of a VAD based on specific neurosonographic ventricular measurements. The process measures were the time taken to insert a VAD after neurosonographic criteria were met, and compliance with postoperative head ultrasounds and VAD taps. The balancing measure was the complication rate related to earlier VAD insertion.

Setting

At the beginning of 2020, after 12 months of multidisciplinary protocol development, an early intervention management pathway for the management of preterm infants with IVH was instituted at our center. It is the quaternary referral site for pediatric neurosurgical care for the province of British Columbia, Canada. It is equipped with a large level IV neonatal intensive care unit (NICU) with 56 acute care and 14 step-down beds, and is a member of the Hydrocephalus Clinical Research Network (HCRN).

Management of patients in historical cohort

Prior to the implementation of this new management pathway, infants with PHVD at our institution, like most centers in North America, were managed with temporizing procedures if they manifested symptoms and/or signs of elevated intracranial pressure ^{Reference Wellons, Shannon and Holubkov8} ; radiologic assessment of ventricular size played an ancillary role in evaluation of a patient for temporizing therapy. Similarly, tapping of the VAD was usually done to mitigate clinical symptomatology rather than to achieve a target ventricular size. Management of these infants was not standardized across neonatologists or neurosurgeons, and there was evidence of intra-center variation in how these infants were treated, both anecdotally at our site as well as in the literature. ^{Reference El-Dib, Limbrik and Inder9}

Protocol development

Our neonatologists expressed an interest in standardizing the care of these infants and exploring the possibility of adapting an early intervention management philosophy for PHVD for use in our local environment. A working group comprised of a lead neurosurgeon, neonatologist and neuroradiologist iteratively refined the details of a management protocol, based on the Early versus Late Ventricular Intervention Study (ELVIS), ^{Reference de Vries, Groenendaal and Liem10} that was eventually agreed upon by all stakeholders. Key elements of discussion regarding how to operationalize an ELVIS-based protocol in our local environment included establishing a ventricular size threshold for surgical temporization, the frequency of ultrasound surveillance, standardization of radiologic reporting of ultrasound evaluations, developing policies and procedures to facilitate the transport of infants from peripheral NICUs for possible surgical intervention and how to train and maintain competence in VAD tapping procedures amongst our NICU colleagues. As a part of protocol implementation, the neurosurgical team, who previously performed VAD taps at our institution, published a tapping procedure document on the hospital intranet and demonstrated proper tapping technique to a critical mass of neonatologists who then propagated the technique to other faculty, staff and trainees in their department. Members of the neurosurgical team provided ongoing training and assistance with this intervention when requested.

Because this new management approach would entail an increased intensity of intervention in fragile premature infants compared to our historical practice, we decided to develop and evaluate the protocol using a quality improvement methodology focused primarily on safety. The fully developed protocol was posted on the hospital intranet, and educational sessions for neonatologists at our and peripheral sites were held pre-implementation and on a regular basis thereafter.

Selection of patients

Preterm infants (born < 32 weeks of gestation) with grade III/IV IVH ^{Reference Papile, Burstein, Burstein and Koffler11} or those with any grade of IVH associated with ventricular dilatation on ultrasonography were included in the new management pathway.

Screening ultrasound recommendations

Screening for IVH in premature infants was in accordance with the Canadian Neonatal Network’s clinical practice guideline regarding ultrasound screening for brain injury in preterm infants. ^{Reference Mohammad, Scott and Leijser12} Once an ultrasound scan detected IVH in an infant, the Levene index was measured to assess for ventriculomegaly. ^{Reference Levene13} If the ventricular index measured in mm was less than the 97^th percentile (p97) for post-menstrual age, a scan was repeated in a week. If the repeat scan did not show any change in ventricular size, subsequent imaging was done two weeks later. If at that point, there was no progression, the next ultrasound scan was done 4–6 weeks later to look for periventricular leukomalacia. However, if the ventricles were enlarging, scans were repeated weekly. Anterior horn width ^{Reference Davies, Swaminathan, Chuang and Betheras14} was also documented in all patients but was not a criterion considered for VAD insertion.

Apart from radiological assessment, routine clinical assessments were also performed. This included daily measurement of head circumference and documentation of symptoms or signs of raised intracranial pressure by the neonatologists. These comprised apnea/bradycardia out of proportion to degree of immaturity and without any other known cause, bulging of the anterior fontanel, splaying of the calvarial sutures, or additional specific neurological findings such as altered level of consciousness, downward deviation of the eyes and seizures. The presence of two or more of these signs was considered clinically significant. ^{Reference Flanders, Kimmel and Lang15}

Intervention recommendations

If the ultrasound showed that the Levene index in either of the ventricles had crossed the p97 threshold, indicating a diagnosis of PHVD, the neurosurgery team was consulted so that they could follow the subsequent scans. Repeat ultrasound scans thereafter were done twice a week or earlier if the infant developed any clinical sign of raised intracranial pressure. If the p97 + 4 mm threshold was crossed, VAD insertion was arranged with a goal of placement within three days of crossing the threshold. In the meantime, daily serial lumbar punctures (up to a maximum of 3) were recommended, with an aim of draining 10 ml/kg of CSF each time; the decision to perform a lumbar puncture was left to the discretion of the neonatology team, based on factors such as the presence of symptoms of elevated intracranial pressure, the general medical status of the infant and/or whether VAD placement was imminent. The three-day VAD-placement target was felt to be reasonable and realistic and was put in place to avoid a prolonged rise in ventricular size prior to surgical temporization.

If the patient was in a peripheral NICU, the process of transfer to our institution was initiated when they crossed the p97 threshold (i.e. at an ultrasonographic diagnosis of PHVD), optimistically allowing for their arrival before they crossed the p97 + 4 mm surgical intervention threshold, but also recognizing that some infants who were transferred on this basis would stabilize their ventricular size below the intervention threshold and therefore not require surgery.

Surgical procedure

The VAD was placed with the infant on the operating room table under general anesthesia. All procedures occurred during the day, with experienced anesthesia and nursing teams readily available. A curvilinear incision was made, centered on the corner of the anterior fontanel. A unitized reservoir with a 3–4 cm ventricular catheter was inserted into the lateral ventricle under ultrasound guidance, and 10 ml/kg of CSF was aspirated to confirm patency. Intravenous antibiotic administration before the skin incision, hand scrub and double gloving by all participants in the operation, preparation of the surgical field with non-alcohol iodine-based prep and the use of iodine-impregnated incision tape were ensured in all patients. These were adapted from the HCRN CSF shunt infection prevention protocol. ^{Reference Chu, Jensen and Holubkov16} Postoperatively, the child was transferred back to the NICU for monitoring.

Ventricular access device tapping

Portable ultrasound scans were performed in the NICU, daily in the morning on the weekdays and once over the weekend. The VAD was tapped daily at the bedside by one of the neonatologists after the final ultrasound report with ventricular size indices (Levene index, anterior horn width) was reviewed and the measurements recorded, with 10 ml/kg of CSF being aspirated at a rate of 1 ml/kg/min. A 25-gauge butterfly needle connected to a 10 ml syringe was used, ensuring sterile precautions. Some infants required modification of the daily 10ml/kg tapping standard to accommodate two 10ml/kg taps per day, depending on the unique clinical circumstance. Clear stopping rules for VAD taps were put in place; taps were to be held, and neurosurgical opinion sought, if new intraventricular, intraparenchymal or extraaxial blood was seen on ultrasound, there was clinical concern of infection at the VAD site, there was technical difficulty in accessing the reservoir or aspirating the full volume of CSF, or the fontanel was sunken at the beginning of assessment.

Daily taps were continued until the Levene index fell below p97 (our prescribed target). Occasionally, we observed instances where the Levine index appeared to stabilize below p97 + 4 mm but above p97 despite repeated taps and attempts to achieve the p97 target. In these instances, one or more tap “holidays” of variable duration were then observed, whereby ultrasound assessments were carried out per protocol but tapping was only reinstituted if the Levene index again increased above p97 + 4 mm. As infants approached term-equivalent age, consideration was given to whether the infant required a permanent CSF diversionary procedure on the basis of evaluating the overall clinical status of the child (head circumference trajectory, presence or absence of clinical symptoms or signs of hydrocephalus, radiologic assessment of ventricular size) rather than on ventricular size criteria alone. If the infant did not require a permanent procedure whilst in the NICU, they continued outpatient neurosurgical surveillance for hydrocephalus with serial clinical and imaging assessments. The decision to proceed with a permanent CSF diversionary procedure was not strictly protocolized, but was consistent with our management of other infants being assessed for hydrocephalus treatment.

Data collection and statistical analysis

Data were collected retrospectively from the electronic medical record and a patient database for infants treated after introduction of the new protocol in 2020. For the historical cohort of patients treated from 2018 to 2019, relevant data were retrieved from their electronic medical records. Variables collected from both patient groups included gestational age and weight at birth, gender, IVH grade, head circumference percentile at the time of surgery and complications related to the intervention (VAD obstruction, infection, CSF leak from the wound and fresh intraventricular/parenchymal/extraaxial hemorrhage documented on imaging). The time intervals between the ultrasound finding of Levene index crossing p97 (i.e. diagnosis of PHVD) and when neurosurgery was consulted, and the interval between the Levene index crossing the p97 + 4 mm surgical threshold and VAD insertion, were determined. Where appropriate, these data were compared between both groups. For the patients managed with the new protocol, compliance rates to prescribed head ultrasound frequency and VAD tapping rules were calculated, and the reasons for protocol deviation/violation were documented.

Data were analyzed using R (version 4.3.3, R Foundation for Statistical Computing, Vienna, Austria). Frequency and percentage were used for categorical variables. Median with inter-quartile range (IQR) was used for continuous variables. Categorical variables were compared using either Fisher’s exact test or Chi-square test, and continuous variables were compared using the Mann-Whitney U (Wilcoxon rank-sum) test. A P value of<0.05 was considered significant.