Evolving trends in the surgical, anaesthetic, and intensive care management of acute spinal cord injuries in the UK

PURPOSE

We surveyed the treatment of acute spinal cord injuries in the UK and compared current practices with 10 years ago.

METHODS

A questionnaire survey was conducted amongst neurosurgeons, neuroanaesthetists, and neurointensivists that manage patients with acute spinal cord injuries. The survey gave two scenarios (complete and incomplete cervical spinal cord injuries). We obtained opinions on the speed of transfer, timing and aim of surgery, choice of anaesthetic, intraoperative monitoring, targets for physiological parameters, and drug treatments.

RESULTS

We received responses from 78.6% of UK units that manage acute spinal cord injuries (33 neurosurgeons, 56 neuroanaesthetists/neurointensivists). Most neurosurgeons operate within 12 h for incomplete (82%) and complete (64%) injuries. There is a significant shift from 10 years ago, when only 61% (incomplete) and 30% (complete) of neurosurgeons operated within 12 h. The preferred anaesthetic technique in 2022 is total intravenous anaesthesia (TIVA), used by 69% of neuroanaesthetists. Significantly more intraoperative monitoring is now used at least sometimes, including bispectral index (91%), non-invasive cardiac output (62%), and neurophysiology (73-77%). Methylprednisolone is no longer used by surgeons. Achieving at least 80 mmHg mean arterial blood pressure is recommended by 70% neurosurgeons, 62% neuroanaesthetists, and 75% neurointensivists.

CONCLUSIONS

Between 2012 and 2022, there was a paradigm shift in managing acute spinal cord injuries in the UK with earlier surgery and more intraoperative monitoring. Variability in practice persists due to lack of high-quality evidence and consensus guidelines.

Adverse Effect of Neurogenic, Infective, and Inflammatory Fever on Acutely Injured Human Spinal Cord

This study aims to determine the effect of neurogenic, inflammatory, and infective fevers on acutely injured human spinal cord. In 86 patients with acute, severe traumatic spinal cord injuries (TSCIs; American Spinal Injury Association Impairment Scale (AIS), grades A-C) we monitored (starting within 72 h of injury, for up to 1 week) axillary temperature as well as injury site cord pressure, microdialysis (MD), and oxygen. High fever (temperature ≥38°C) was classified as neurogenic, infective, or inflammatory. The effect of these three fever types on injury-site physiology, metabolism, and inflammation was studied by analyzing 2864 h of intraspinal pressure (ISP), 1887 h of MD, and 840 h of tissue oxygen data. High fever occurred in 76.7% of the patients. The data show that temperature was higher in neurogenic than non-neurogenic fever. Neurogenic fever only occurred with injuries rostral to vertebral level T4. Compared with normothermia, fever was associated with reduced tissue glucose (all fevers), increased tissue lactate to pyruvate ratio (all fevers), reduced tissue oxygen (neurogenic + infective fevers), and elevated levels of pro-inflammatory cytokines/chemokines (infective fever). Spinal cord metabolic derangement preceded the onset of infective but not neurogenic or inflammatory fever. By considering five clinical characteristics (level of injury, axillary temperature, leukocyte count, C-reactive protein [CRP], and serum procalcitonin [PCT]), it was possible to confidently distinguish neurogenic from non-neurogenic high fever in 59.3% of cases. We conclude that neurogenic, infective, and inflammatory fevers occur commonly after acute, severe TSCI and are detrimental to the injured spinal cord with infective fever being the most injurious. Further studies are required to determine whether treating fever improves outcome. Accurately diagnosing neurogenic fever, as described, may reduce unnecessary septic screens and overuse of antibiotics in these patients.

Spinal cord perfusion pressure correlates with breathing function in patients with acute, cervical traumatic spinal cord injuries: an observational study

OBJECTIVE

This study aims to determine the relationship between spinal cord perfusion pressure (SCPP) and breathing function in patients with acute cervical traumatic spinal cord injuries.

METHODS

We included 8 participants without cervical TSCI plus 13 patients with cervical traumatic spinal cord injuries, American Spinal Injury Association Impairment Scale grades A-C. In the TSCI patients, we monitored intraspinal pressure from the injury site for up to a week and computed the SCPP as mean arterial pressure minus intraspinal pressure. Breathing function was quantified by diaphragmatic electromyography using an EDI (electrical activity of the diaphragm) nasogastric tube as well as by ultrasound of the diaphragm and the intercostal muscles performed when sitting at 20°-30°.

RESULTS

We analysed 106 ultrasound examinations (total 1370 images/videos) and 198 EDI recordings in the patients with cervical traumatic spinal cord injuries. During quiet breathing, low SCPP (< 60 mmHg) was associated with reduced EDI-peak (measure of inspiratory effort) and EDI-min (measure of the tonic activity of the diaphragm), which increased and then plateaued at SCPP 60-100 mmHg. During quiet and deep breathing, the diaphragmatic thickening fraction (force of diaphragmatic contraction) plotted versus SCPP had an inverted-U relationship, with a peak at SCPP 80-90 mmHg. Diaphragmatic excursion (up and down movement of the diaphragm) during quiet breathing did not correlate with SCPP, but diaphragmatic excursion during deep breathing plotted versus SCPP had an inverse-U relationship with a peak at SCPP 80-90 mmHg. The thickening fraction of the intercostal muscles plotted versus SCPP also had inverted-U relationship, with normal intercostal function at SCPP 80-100 mmHg, but failure of the upper and middle intercostals to contract during inspiration (i.e. abdominal breathing) at SCPP < 80 or > 100 mmHg.

CONCLUSIONS

After acute, cervical traumatic spinal cord injuries, breathing function depends on the SCPP. SCPP 80-90 mmHg correlates with optimum diaphragmatic and intercostal muscle function. Our findings raise the possibility that intervention to maintain SCPP in this range may accelerate ventilator liberation which may reduce stay in the neuro-intensive care unit.

Duroplasty for injured cervical spinal cord with uncontrolled swelling: protocol of the DISCUS randomized controlled trial

BACKGROUND

Cervical traumatic spinal cord injury is a devastating condition. Current management (bony decompression) may be inadequate as after acute severe TSCI, the swollen spinal cord may become compressed against the surrounding tough membrane, the dura. DISCUS will test the hypothesis that, after acute, severe traumatic cervical spinal cord injury, the addition of dural decompression to bony decompression improves muscle strength in the limbs at 6 months, compared with bony decompression alone.

METHODS

This is a prospective, phase III, multicenter, randomized controlled superiority trial. We aim to recruit 222 adults with acute, severe, traumatic cervical spinal cord injury with an American Spinal Injury Association Impairment Scale grade A, B, or C who will be randomized 1:1 to undergo bony decompression alone or bony decompression with duroplasty. Patients and outcome assessors are blinded to study arm. The primary outcome is change in the motor score at 6 months vs. admission; secondary outcomes assess function (grasp, walking, urinary + anal sphincters), quality of life, complications, need for further surgery, and mortality, at 6 months and 12 months from randomization. A subgroup of at least 50 patients (25/arm) also has observational monitoring from the injury site using a pressure probe (intraspinal pressure, spinal cord perfusion pressure) and/or microdialysis catheter (cord metabolism: tissue glucose, lactate, pyruvate, lactate to pyruvate ratio, glutamate, glycerol; cord inflammation: tissue chemokines/cytokines). Patients are recruited from the UK and internationally, with UK recruitment supported by an integrated QuinteT recruitment intervention to optimize recruitment and informed consent processes. Estimated study duration is 72 months (6 months set-up, 48 months recruitment, 12 months to complete follow-up, 6 months data analysis and reporting results).

DISCUSSION

We anticipate that the addition of duroplasty to standard of care will improve muscle strength; this has benefits for patients and carers, as well as substantial gains for health services and society including economic implications. If the addition of duroplasty to standard treatment is beneficial, it is anticipated that duroplasty will become standard of care.

TRIAL REGISTRATION

IRAS: 292031 (England, Wales, Northern Ireland) - Registration date: 24 May 2021, 296518 (Scotland), ISRCTN: 25573423 (Registration date: 2 June 2021); ClinicalTrials.gov number : NCT04936620 (Registration date: 21 June 2021); NIHR CRN 48627 (Registration date: 24 May 2021).

Acute, severe traumatic spinal cord injury: improving urinary bladder function by optimizing spinal cord perfusion

OBJECTIVE

The authors sought to investigate the effect of acute, severe traumatic spinal cord injury on the urinary bladder and the hypothesis that increasing the spinal cord perfusion pressure improves bladder function.

METHODS

In 13 adults with traumatic spinal cord injury (American Spinal Injury Association Impairment Scale grades A-C), a pressure probe and a microdialysis catheter were placed intradurally at the injury site. We varied the spinal cord perfusion pressure and performed filling cystometry. Patients were followed up for 12 months on average.

RESULTS

The 13 patients had 63 fill cycles; 38 cycles had unfavorable urodynamics, i.e., dangerously low compliance (< 20 mL/cmH2O), detrusor overactivity, or dangerously high end-fill pressure (> 40 cmH2O). Unfavorable urodynamics correlated with periods of injury site hypoperfusion (spinal cord perfusion pressure < 60 mm Hg), hyperperfusion (spinal cord perfusion pressure > 100 mm Hg), tissue glucose < 3 mM, and tissue lactate to pyruvate ratio > 30. Increasing spinal cord perfusion pressure from 67.0 ± 2.3 mm Hg (average ± SE) to 92.1 ± 3.0 mm Hg significantly reduced, from 534 to 365 mL, the median bladder volume at which the desire to void was first experienced. All patients with dangerously low average initial bladder compliance (< 20 mL/cmH2O) maintained low compliance at follow-up, whereas all patients with high average initial bladder compliance (> 100 mL/cmH2O) maintained high compliance at follow-up.

CONCLUSIONS

We conclude that unfavorable urodynamics develop within days of traumatic spinal cord injury, thus challenging the prevailing notion that the detrusor is initially acontractile. Urodynamic studies performed acutely identify patients with dangerously low bladder compliance likely to benefit from early intervention. At this early stage, bladder function is dynamic and is influenced by fluctuations in the physiology and metabolism at the injury site; therefore, optimizing spinal cord perfusion is likely to improve urological outcome in patients with acute severe traumatic spinal cord injury.

Spinal Cord Perfusion Pressure Correlates with Anal Sphincter Function in a Cohort of Patients with Acute, Severe Traumatic Spinal Cord Injuries

Background

Acute, severe traumatic spinal cord injury often causes fecal incontinence. Currently, there are no treatments to improve anal function after traumatic spinal cord injury. Our study aims to determine whether, after traumatic spinal cord injury, anal function can be improved by interventions in the neuro-intensive care unit to alter the spinal cord perfusion pressure at the injury site.

Methods

We recruited a cohort of patients with acute, severe traumatic spinal cord injuries (American Spinal Injury Association Impairment Scale grades A–C). They underwent surgical fixation within 72 h of the injury and insertion of an intrathecal pressure probe at the injury site to monitor intraspinal pressure and compute spinal cord perfusion pressure as mean arterial pressure minus intraspinal pressure. Injury-site monitoring was performed at the neuro-intensive care unit for up to a week after injury. During monitoring, anorectal manometry was also conducted over a range of spinal cord perfusion pressures.

Results

Data were collected from 14 patients with consecutive traumatic spinal cord injury aged 22–67 years. The mean resting anal pressure was 44 cmH₂O, which is considerably lower than the average for healthy patients, previously reported at 99 cmH₂O. Mean resting anal pressure versus spinal cord perfusion pressure had an inverted U-shaped relation (Ȓ² = 0.82), with the highest resting anal pressures being at a spinal cord perfusion pressure of approximately 100 mmHg. The recto-anal inhibitory reflex (transient relaxation of the internal anal sphincter during rectal distension), which is important for maintaining fecal continence, was present in 90% of attempts at high (90 mmHg) spinal cord perfusion pressure versus 70% of attempts at low (60 mmHg) spinal cord perfusion pressure (P < 0.05). During cough, the rise in anal pressure from baseline was 51 cmH₂O at high (86 mmHg) spinal cord perfusion pressure versus 37 cmH₂O at low (62 mmHg) spinal cord perfusion pressure (P < 0.0001). During anal squeeze, higher spinal cord perfusion pressure was associated with longer endurance time and spinal cord perfusion pressure of 70–90 mmHg was associated with stronger squeeze. There were no complications associated with anorectal manometry.

Conclusions

Our data indicate that spinal cord injury causes severe disruption of anal sphincter function. Several key components of anal continence (resting anal pressure, recto-anal inhibitory reflex, and anal pressure during cough and squeeze) markedly improve at higher spinal cord perfusion pressure. Maintaining too high of spinal cord perfusion pressure may worsen anal continence.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-021-01232-1.

Effects of local hypothermia-rewarming on physiology, metabolism and inflammation of acutely injured human spinal cord

In five patients with acute, severe thoracic traumatic spinal cord injuries (TSCIs), American spinal injuries association Impairment Scale (AIS) grades A-C, we induced cord hypothermia (33 °C) then rewarming (37 °C). A pressure probe and a microdialysis catheter were placed intradurally at the injury site to monitor intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), tissue metabolism and inflammation. Cord hypothermia-rewarming, applied to awake patients, did not cause discomfort or neurological deterioration. Cooling did not affect cord physiology (ISP, SCPP), but markedly altered cord metabolism (increased glucose, lactate, lactate/pyruvate ratio (LPR), glutamate; decreased glycerol) and markedly reduced cord inflammation (reduced IL1β, IL8, MCP, MIP1α, MIP1β). Compared with pre-cooling baseline, rewarming was associated with significantly worse cord physiology (increased ICP, decreased SCPP), cord metabolism (increased lactate, LPR; decreased glucose, glycerol) and cord inflammation (increased IL1β, IL8, IL4, IL10, MCP, MIP1α). The study was terminated because three patients developed delayed wound infections. At 18-months, two patients improved and three stayed the same. We conclude that, after TSCI, hypothermia is potentially beneficial by reducing cord inflammation, though after rewarming these benefits are lost due to increases in cord swelling, ischemia and inflammation. We thus urge caution when using hypothermia-rewarming therapeutically in TSCI.

Acute Spinal Cord Injury: Monitoring Lumbar Cerebrospinal Fluid Provides Limited Information about the Injury Site

In some centers, monitoring lumbar cerebrospinal fluid (CSF) is used to guide management of patients with acute traumatic spinal cord injuries (TSCI) and draining lumbar CSF to improve spinal cord perfusion. Here, we investigate whether the lumbar CSF provides accurate information about the injury site and the effect of draining lumbar CSF on injury site perfusion. In 13 TSCI patients, we simultaneously monitored lumbar CSF pressure (CSFP) and intraspinal pressure (ISP) from the injury site. Using CSFP or ISP, we computed spinal cord perfusion pressure (SCPP), vascular pressure reactivity index (sPRx) and optimum SCPP (SCPP_opt). We also assessed the effect on ISP of draining 10 mL CSF. Metabolites at the injury site were compared with metabolites in the lumbar CSF. We found that ISP was pulsatile, but CSFP had low pulse pressure and was non-pulsatile 21% of the time. There was weak or no correlation between CSFP versus ISP (R = -0.11), SCPP_(csf) versus SCPP_(ISP) (R = 0.39), and sPRx_(csf) versus sPRx_(ISP) (R = 0.45). CSF drainage caused no significant change in ISP in 7/12 patients and a significant drop of <5 mm Hg in 4/12 patients and of ∼8 mm Hg in 1/12 patients. Metabolite concentrations in the CSF versus the injury site did not correlate for lactate (R = 0.00), pyruvate (R = -0.12) or lactate-to-pyruvate ratio (R = -0.05) with weak correlations noted for glucose (R = 0.31), glutamate (R = 0.61), and glycerol (R = 0.56). We conclude that, after a severe TSCI, monitoring from the lumbar CSF provides only limited information about the injury site and that lumbar CSF drainage does not effectively reduce ISP in most patients.

Heterogeneous effect of increasing spinal cord perfusion pressure on sensory evoked potentials recorded from acutely injured human spinal cord

PURPOSE

To investigate the effect of increasing spinal cord perfusion pressure (SCPP) on sensory evoked potentials (SEPs) and injury site metabolism in patients with severe traumatic spinal cord injury TSCI.

MATERIALS AND METHODS

In 12 TSCI patients we placed a pressure probe, a microdialysis catheter and a strip electrode with 8 contacts on the surface of the injured cord. We monitored SCPP, lactate-to-pyruvate ratio (LPR) and SEPs (after median or posterior tibial nerve stimulation).

RESULTS

Increase in SCPP by ~20 mmHg produced a heterogeneous response in SEPs and injury site metabolism. In some patients, SEP amplitudes increased and the LPR decreased indicating improved tissue metab olism. In others, SEP amplitudes decreased and the LPR increased indicating more impaired metabolism. Compared with patients who did not improve at follow-up, those who improved had significantly more electrode contacts with SEP amplitude increase in response to increasing SCPP.

CONCLUSIONS

Increasing SCPP after acute, severe TSCI may be beneficial (if associated with increase in SEP amplitude) or detrimental (if associated with decrease in SEP amplitude). Our findings support individualized management of patients with acute, severe TSCI guided by monitoring from the injury site rather than applying universal blood pressure targets as is current clinical practice.

P75 Factors that predict degree of spinal cord compression and optimal spinal cord perfusion pressure in patients with acute, severe traumatic spinal cord injuries

Objectives

To identify factors which predict intra-spinal pressure (ISP) and optimal spinal cord perfusion pressure (SCPPopt) in patients with acute, severe traumatic spinal cord injuries (TSCI) that could be used instead of invasive ISP monitoring.

Methods

We monitored ISP, mean arterial pressure (MAP) and computed spinal cord perfusion pressure (SCPP), spinal pressure reactivity index (sPRx) and SCPPopt in 64 TSCI patients, AIS grades A–C who were part of the Injured Spinal Cord Pressure Evaluation (ISCoPE) study. We recorded baseline, injury/imaging and management variables which may influence ISP/SCPPopt. Statistical analysis was used to investigate differences in ISP/SCPPopt between the variables

Results

51% (34/64) had U-shaped sPRx vs. SCPP curve in the first 24 hours after surgery. Mean SCPPopt was 74 mmHg (range 48–103). Lower mean 24 hour ISP was found with: older age, alcohol excess, non-conus medullaris injury, duroplasty and less surgical bleeding. Mean ISP on day 1 after surgery correlates with mean ISP over the first week. Lower 24 hour SCPPopt was associated with: higher mean ISP and conus medullaris injury. No MRI factors predicted ISP or SCPPopt.

Conclusions

Several factors predict ISP. Modifiable factors to reduce ISP are less surgical bleeding and expansion duroplasty. No variables predict SCPPopt. ISP monitoring remains the only way to estimate SCPPopt to help prevent secondary damage and we continue to support use of ISP monitoring to individualise management in acute, severe TSCI.

Gastrointestinal motility following thoracic surgery: the effect of thoracic epidural analgesia. A randomised controlled trial

Backgrounds

Impairment of gastrointestinal (GI) motility is an undesirable but inevitable consequence of surgery. This prospective randomised controlled study tested the hypothesis that postoperative thoracic epidural analgesia (TEA) with ropivacaine or a combination of ropivacaine and morphine accelerates postoperative GI function and shortens the duration of postoperative ileus following major thoracic surgery compared to intravenous (IV) morphine.

Methods

Thirty patients scheduled for major thoracic surgery were randomised to three groups. All patients had bowel motility assessments 1 week preoperatively. All patients received general anaesthesia. Group Ep-R received TEA with ropivacaine; group Ep-RM received TEA with ropivacaine and morphine and group IV-M received IV morphine via patient controlled analgesia pump (PCA). Bowel motility was assessed by clinical examination in addition to oro-ceacal transit time (OCTT) on the first and third postoperative days and colonic transit time (CTT).

Results

Overall the OCTT demonstrated a 2.5-fold decrease in bowel motility on the first postoperative day. The OCTT test revealed statistically significant differences between all groups (Ep-R vs Ep-RM, p = 0.43/Ep-R vs IV-M, p = 0.039 / Ep-RM vs IV-M, p < 0.001). Also, very significant differences were found in the OCCT test between days (Ep-R vs Ep-RM, p < 0.001/Ep-R vs IV-M, p < 0.001 / Ep-RM vs IV-M, p = 0.014). There were no significant differences in the CTT test or the clinical signs between groups. However, 70% of the patients in the Ep-R group and 80% in the Ep-RM group defecated by the third day compared to only 10% in the IV-M group, (p = 0.004).

Conclusions

Objective tests demonstrated the delayed motility of the whole GI system postoperatively following thoracic surgery. They also demonstrated that continuous epidural analgesia with or without morphine improved GI motility in comparison to intravenous morphine. These differences were more pronounced on the third postoperative day.

Trial registration

ISRCTN number: 11953159, retrospectively registered on 20/03/2017.

Metabolic profile of injured human spinal cord determined using surface microdialysis

The management of patients having traumatic spinal cord injury would benefit from understanding and monitoring of spinal cord metabolic states. We hypothesized that the metabolism of the injured spinal cord could be visualized using Kohonen self-organizing maps. Sixteen patients with acute, severe spinal cord injuries were studied. Starting within 72 h of the injury, and for up to a week, we monitored the injury site hourly for tissue glucose, lactate, pyruvate, glutamate, and glycerol using microdialysis as well as intraspinal pressure and spinal cord perfusion pressure. A Kohonen map, which is an unsupervised, self-organizing topology-preserving neural network, was used to analyze 3366 h of monitoring data. We first visualized the different spinal cord metabolic states. Our data show that the injured cord assumes one or more of four metabolic states. On the basis of their metabolite profiles, we termed these states near-normal, ischemic, hypermetabolic, and distal. We then visualized how patients' intraspinal pressure and spinal cord perfusion pressure affect spinal cord metabolism. This revealed that for more than 60% of the time, spinal cord metabolism is patient-specific; periods of high intraspinal pressure or low perfusion pressure are not associated with specific spinal cord metabolic patterns. Finally, we determined relationships between spinal cord metabolism and neurological status. Patients with complete deficits have shorter periods of near-normal spinal cord metabolic states (7 ± 4% vs. 58 ± 12%, p < 0.01, mean ± standard error) and more variable injury site metabolic responses (metabolism spread in 70 ± 11 vs. 40 ± 6 hexagons, p < 0.05), compared with patients who have incomplete neurological deficits. We conclude that Kohonen maps allow us to visualize the metabolic responses of the injured spinal cord and may thus aid us in treating patients with acute spinal cord injuries.

Safety profile and probe placement accuracy of intraspinal pressure monitoring for traumatic spinal cord injury: Injured Spinal Cord Pressure Evaluation study

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.

Intraspinal pressure and spinal cord perfusion pressure after spinal cord injury: an observational study

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.

Expansion duroplasty improves intraspinal pressure, spinal cord perfusion pressure, and vascular pressure reactivity index in patients with traumatic spinal cord injury: injured spinal cord pressure evaluation study

We recently showed that, after traumatic spinal cord injury (TSCI), laminectomy does not improve intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), or the vascular pressure reactivity index (sPRx) at the injury site sufficiently because of dural compression. This is an open label, prospective trial comparing combined bony and dural decompression versus laminectomy. Twenty-one patients with acute severe TSCI had re-alignment of the fracture and surgical fixation; 11 had laminectomy alone (laminectomy group) and 10 had laminectomy and duroplasty (laminectomy+duroplasty group). Primary outcomes were magnetic resonance imaging evidence of spinal cord decompression (increase in intradural space, cerebrospinal fluid around the injured cord) and spinal cord physiology (ISP, SCPP, sPRx). The laminectomy and laminectomy+duroplasty groups were well matched. Compared with the laminectomy group, the laminectomy+duroplasty group had greater increase in intradural space at the injury site and more effective decompression of the injured cord. In the laminectomy+duroplasty group, ISP was lower, SCPP higher, and sPRx lower, (i.e., improved vascular pressure reactivity), compared with the laminectomy group. Laminectomy+duroplasty caused cerebrospinal fluid leak that settled with lumbar drain in one patient and pseudomeningocele that resolved completely in five patients. We conclude that, after TSCI, laminectomy+duroplasty improves spinal cord radiological and physiological parameters more effectively than laminectomy alone.

Variability in the treatment of acute spinal cord injury in the United Kingdom: results of a national survey

The aim of this study was to examine how traumatic spinal cord injury is managed in the United Kingdom via a questionnaire survey of all neurosurgical units. We contacted consultant neurosurgeons and neuroanesthetists in all neurosurgical centers that manage patients with acute spinal cord injury. Two clinical scenarios-of complete and incomplete cervical spinal cord injuries-were given to determine local treatment policies. There were 175 responders from the 33 centers (36% response rate). We ascertained neurosurgical views on urgency of transfer, timing of surgery, nature and aim of surgery, as well as neuroanesthetic views on type of anesthetic, essential intraoperative monitoring, drug treatment, and intensive care management. Approximately 70% of neurosurgeons will admit patients with incomplete spinal cord injury immediately, but only 40% will admit patients with complete spinal cord injury immediately. There is no consensus on the timing or even the role of surgery for incomplete or complete injuries. Most (96%) neuroanesthetists avoid anesthetics known to elevate intracranial pressure. What was deemed essential intraoperative monitoring, however, varied widely. Many (22%) neuroanesthetists do not routinely measure arterial blood pressure invasively, central venous pressure (85%), or cardiac output (94%) during surgery. There is no consensus among neuroanesthetists on the optimal levels of arterial blood pressure, or oxygen and carbon dioxide partial arterial pressure. We report wide variability among U.K. neurosurgeons and neuroanesthetists in their treatment of acute traumatic spinal cord injury. Our findings reflect the lack of Class 1 evidence that early surgical decompression and intensive medical management of patients with spinal cord injury improves neurological outcome.

Heart rate variability may identify patients who will develop severe bradycardia during spinal anaesthesia

BACKGROUND AND OBJECTIVES

The reported incidence of cardiac arrest during spinal anaesthesia is 6.4+1.2 per 10,000 patients. Many of these arrests occurred in healthy young patients during minor surgery. This raises the question of whether some of them were avoidable. We investigated the value of Heart Rate Variability (HRV) to identify patients prone to developing severe bradycardia during spinal anaesthesia.

METHODS

Eighty ASA I-II patients, 21-60 years of age, undergoing elective surgery under spinal anaesthesia were studied. The HRV was assessed for 25 min before the spinal block. Two spectral components of HRV were calculated: a low-frequency (LF) and a high-frequency (HF) component. Patients were grouped according to whether bradycardia did or did not develop during spinal anaesthesia.

RESULTS

Nineteen patients developed severe bradycardia (<45 b.p.m.). The mean value of HF before spinal anaesthesia was significantly increased in the bradycardic group (P<0.05). The correlation between baseline heart rate (HR(baseline)) and minimum heart rate and LF, HF during spinal anaesthesia was significant (P<0.01). A receiver operator curve characteristic analysis showed a sensitivity and specificity of HF and HR(baseline) of 65% and 74%, respectively, to predict bradycardia <45 b.p.m. after spinal anaesthesia.

CONCLUSIONS

The present study shows that HF and clinical factors such as patient's HR(baseline) could identify patients prone to developing severe bradycardia during spinal anaesthesia.