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Isaac Phang, Argyro Zoumprouli, Samira Saadoun, and Marios C. Papadopoulos

OBJECTIVE

A novel technique for monitoring intraspinal pressure and spinal cord perfusion pressure in patients with traumatic spinal cord injury was recently described. This is analogous to monitoring intracranial pressure and cerebral perfusion pressure in patients with traumatic brain injury. Because intraspinal pressure monitoring is a new technique, its safety profile and impact on early patient care and long-term outcome after traumatic spinal cord injury are unknown. The object of this study is to review all patients who had intraspinal pressure monitoring to date at the authors' institution in order to define the accuracy of intraspinal pressure probe placement and the safety of the technique.

METHODS

At the end of surgery to fix spinal fractures, a pressure probe was inserted intradurally to monitor intraspinal pressure at the injury site. Postoperatively, CT scanning was performed within 48 hours and MRI at 2 weeks and 6 months. Neurointensive care management and complications were reviewed. The American Spinal Injury Association Impairment Scale (AIS) grade was determined on admission and at 2 to 4 weeks and 12 to 18 months postoperation.

RESULTS

To date, 42 patients with severe traumatic spinal cord injuries (AIS Grades A–C) had undergone intraspinal pressure monitoring. Monitoring started within 72 hours of injury and continued for up to a week. Based on postoperative CT and MRI, the probe position was acceptable in all patients, i.e., the probe was located at the site of maximum spinal cord swelling. Complications were probe displacement in 1 of 42 patients (2.4%), CSF leakage that required wound resuturing in 3 of 42 patients (7.1%), and asymptomatic pseudomeningocele that was diagnosed in 8 of 42 patients (19.0%). Pseudomeningocele was diagnosed on MRI and resolved within 6 months in all patients. Based on the MRI and neurological examination results, there were no serious probe-related complications such as meningitis, wound infection, hematoma, wound breakdown, or neurological deterioration. Within 2 weeks postoperatively, 75% of patients were extubated and 25% underwent tracheostomy. Norepinephrine was used to support blood pressure without complications. Overall, the mean intraspinal pressure was around 20 mm Hg, and the mean spinal cord perfusion pressure was around 70 mm Hg. In laminectomized patients, the intraspinal pressure was significantly higher in the supine than lateral position by up to 18 mm Hg after thoracic laminectomy and 8 mm Hg after cervical laminectomy. At 12 to 18 months, 11.4% of patients had improved by 1 AIS grade and 14.3% by at least 2 AIS grades.

CONCLUSIONS

These data suggest that after traumatic spinal cord injury intradural placement of the pressure probe is accurate and intraspinal pressure monitoring is safe for up to a week. In patients with spinal cord injury who had laminectomy, the supine position should be avoided in order to prevent rises in intraspinal pressure.

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Aaron Lawson McLean, Aimun A. B. Jamjoom, Michael T. C. Poon, Difei Wang, Isaac Phang, Mohamed Okasha, Matthew Boissaud-Cooke, Adam P. Williams, and Aminul I. Ahmed

OBJECTIVE

Freehand external ventricular drain (EVD) insertion is associated with a high rate of catheter misplacement. Image-guided EVD placement with neuronavigation or ultrasound has been proposed as a safer, more accurate alternative with potential to facilitate proper placement and reduce catheter malfunction risk. This study aimed to determine the impact of image-guided EVD placement on catheter tip position and drain functionality.

METHODS

This study is a secondary analysis of a data set from a prospective, multicenter study. Data were collated for EVD placements undertaken in the United Kingdom and Ireland from November 2014 to April 2015. In total, 21 large tertiary care academic medical centers were included.

RESULTS

Over the study period, 632 EVDs were inserted and 65.9% had tips lying free-floating in the CSF. Only 19.6% of insertions took place under image guidance. The use of image guidance did not significantly improve the position of the catheter tip on postoperative imaging, even when stratified by ventricular size. There was also no association between navigation use and drain blockage.

CONCLUSIONS

Image-guided EVD placement was not associated with an increased likelihood of achieving optimal catheter position or with a lower rate of catheter blockage. Educational efforts should aim to enhance surgeons’ ability to apply the technique correctly in cases of disturbed cerebral anatomy or small ventricles to reduce procedural risks and facilitate effective catheter positioning.

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Georgios V. Varsos, Melissa C. Werndle, Zofia H. Czosnyka, Peter Smielewski, Angelos G. Kolias, Isaac Phang, Samira Saadoun, B. Anthony Bell, Argyro Zoumprouli, Marios C. Papadopoulos, and Marek Czosnyka

OBJECT

In contrast to intracranial pressure (ICP) in traumatic brain injury (TBI), intraspinal pressure (ISP) after traumatic spinal cord injury (TSCI) has not received the same attention in terms of waveform analysis. Based on a recently introduced technique for continuous monitoring of ISP, here the morphological characteristics of ISP are observationally described. It was hypothesized that the waveform analysis method used to assess ICP could be similarly applied to ISP.

METHODS

Data included continuous recordings of ISP and arterial blood pressure (ABP) in 18 patients with severe TSCI.

RESULTS

The morphology of the ISP pulse waveform resembled the ICP waveform shape and was composed of 3 peaks representing percussion, tidal, and dicrotic waves. Spectral analysis demonstrated the presence of slow, respiratory, and pulse waves at different frequencies. The pulse amplitude of ISP was proportional to the mean ISP, suggesting a similar exponential pressure-volume relationship as in the intracerebral space. The interaction between the slow waves of ISP and ABP is capable of characterizing the spinal autoregulatory capacity.

CONCLUSIONS

This preliminary observational study confirms morphological and spectral similarities between ISP in TSCI and ICP. Therefore, the known methods used for ICP waveform analysis could be transferred to ISP analysis and, upon verification, potentially used for monitoring TSCI patients.