Tissue-interface pressures on three different support-surfaces for trauma patients

Remaining Cervical Spine Movement Under Different Immobilization Techniques

BACKGROUND

Immobilization of the cervical spine by Emergency Medical Services (EMS) personnel is a standard procedure. In most EMS, multiple immobilization tools are available.The aim of this study is the analysis of residual spine motion under different types of cervical spine immobilization.

METHODS

In this explorative biomechanical study, different immobilization techniques were performed on three healthy subjects. The test subjects' heads were then passively moved to cause standardized spinal motion. The primary endpoints were the remaining range of motion for flexion, extension, bending, and rotation measured with a wireless human motion detector.

RESULTS

In the case of immobilization of the test person (TP) on a straight (0°) vacuum mattress, the remaining rotation of the cervical spine could be reduced from 7° to 3° by additional headblocks. Also, the remaining flexion and extension were reduced from 14° to 3° and from 15° to 6°, respectively. The subjects' immobilization was best on a spine board using a headlock system and the Spider Strap belt system (MIH-Medical; Georgsmarienhütte, Germany). However, the remaining cervical spine extension increased from 1° to 9° if a Speedclip belt system was used (Laerdal; Stavanger, Norway). The additional use of a cervical collar was not advantageous in reducing cervical spine movement with a spine board or vacuum mattress.

CONCLUSIONS

The remaining movement of the cervical spine is minimal when the patient is immobilized on a spine board with a headlock system and a Spider Strap harness system or on a vacuum mattress with additional headblocks. The remaining movement of the cervical spine could not be reduced by the additional use of a cervical collar.

Lateral pressure equalisation as a principle for designing support surfaces to prevent deep tissue pressure ulcers

When immobile or neuropathic patients are supported by beds or chairs, their soft tissues undergo deformations that can cause pressure ulcers. Current support surfaces that redistribute under-body pressures at vulnerable body sites have not succeeded in reducing pressure ulcer prevalence. Here we show that adding a supporting lateral pressure can counter-act the deformations induced by under-body pressure, and that this 'pressure equalisation' approach is a more effective way to reduce ulcer-inducing deformations than current approaches based on redistributing under-body pressure. A finite element model of the seated pelvis predicts that applying a lateral pressure to the soft tissue reduces peak von Mises stress in the deep tissue by a factor of 2.4 relative to a standard cushion (from 113 kPa to 47 kPa)-a greater effect than that achieved by using a more conformable cushion, which reduced von Mises stress to 75 kPa. Combining both a conformable cushion and lateral pressure reduced peak von Mises stresses to 25 kPa. The ratio of peak lateral pressure to peak under-body pressure was shown to regulate deep tissue stress better than under-body pressure alone. By optimising the magnitude and position of lateral pressure, tissue deformations can be reduced to that induced when suspended in a fluid. Our results explain the lack of efficacy in current support surfaces and suggest a new approach to designing and evaluating support surfaces: ensuring sufficient lateral pressure is applied to counter-act under-body pressure.

Demonstration of pressure reduction in a new proof of concept spine board

Pressure injuries are a significant problem following spinal cord injury (SCI). High interface pressures while lying on a spine board during emergency transport appear to play a major role in their formation. The aim of the present study was to assess the interface pressures and sensing area between the body and the standard spine board (SSB) and a proof of concept spine board prototype (P-5). Twenty-one able-bodied subjects were assessed on each board. Interface pressures and sensing area were recorded every minute over 15 min. The mean peak pressure was higher on the SSB at the head, scapulothoracic (S-T), sacroiliac (S-I), and heels (227.6 mmHg, 148.9 mmHg, 360.3 mmHg, and 179.3 mmHg) compared to P-5 (51.9 mmHg, 60.1 mmHg, 66.8 mmHg, and 60.2 mmHg). The peak pressure index (PPI) at the head, S-T and S-I was higher on the SSB (100.2 mmHg, 101.6 mmHg, and 270.6 mmHg) compared to P-5 (41.6 mmHg, 51.9 mmHg and 58.7 mmHg). An analysis using pairwise comparisons for repeated measures showed that interface pressures (p < .05) and PPI (p < .001) were reduced at all locations. Modifications of a spine board incorporated in P-5 can dramatically reduce interface pressures and reduce pressure injury formation.

Comparing the Efficacy of Methods for Immobilizing the Cervical Spine

STUDY DESIGN

This was a prospective simulator study with 16 healthy male subjects.

OBJECTIVE

The aim of this study was to compare the relative efficacy of immobilization systems in limiting involuntary movements of the cervical spine using a dynamic simulation model.

SUMMARY OF BACKGROUND DATA

Relatively few studies have tested the efficacy of immobilization methods for limiting involuntary cervical movement, and only one of these studies used a dynamic simulation system to do so.

METHODS

Immobilization configurations tested were cot alone, cot with cervical collar, long spine board (LSB) with cervical collar and head blocks, and vacuum mattress (VM) with cervical collar. A motion platform reproduced shocks and vibrations from ambulance and helicopter field rides, as well as more severe shocks and vibrations that might be encountered on rougher terrain and in inclement weather (designated as an "augmented" ride). Motion capture technology quantitated involuntary cervical rotation, flexion/extension, and lateral bend. The mean and 95% confidence interval of the mean were calculated for the root mean square of angular changes from the starting position and for the maximum range of motion.

RESULTS

All configurations tested decreased cervical rotation and flexion/extension relative to the cot alone. However, the LSB and VM were significantly more effective in decreasing cervical rotation than the cervical collar, and the LSB decreased rotation more than the VM in augmented rides. The LSB and VM, but not the cervical collar, significantly limited cervical lateral bend relative to the cot alone.

CONCLUSION

Under the study conditions, the LSB and the VM were more effective in limiting cervical movement than the cervical collar. Under some conditions, the LSB decreased repetitive and acute movements more than the VM. Further studies using simulation and other approaches will be essential for determining the safest, most effective configuration should providers choose to immobilize patients with suspected spinal injuries.

LEVEL OF EVIDENCE

3.

A New Craniothoracic Mattress for Immobilization of the Cervical Spine in Critical Care Patients

Current immobilization techniques of the cervical spine are associated with complications including pressure ulcers, discomfort, and elevated intracranial pressures with limited access to the thorax and airway. In this study, a newly developed craniothoracic immobilizer (Pharaoh mattress) for critical care patients with cervical injury was tested for its restriction of cervical movement, peak interface pressures, comfort, and radiolucency, and compared with headblocks strapped to a spineboard. Cervical movement was measured by roentgen stereophotogrammetric analysis in 5 fresh frozen cadavers. Peak interface and discomfort pressures were measured in 10 healthy volunteers. Radiographic absorption was calculated by measuring the total emission radiation with and without immobilizer. The Pharaoh mattress caused a mean restriction of 59% (SD: 15) flexion-extension, 77% (SD: 14) lateral bending, and 93% (SD: 3) rotation, compared with the unrestricted situation. No significant differences in restriction of cervical movement were found between headblocks strapped to a spineboard and the Pharaoh mattress. The mean peak pressures on the Pharaoh mattress were significantly lower than on the spineboard. Healthy volunteers gave significantly lower numeric discomfort scores on the Pharaoh mattress than on the spineboard. The Pharaoh mattress absorbed more x-rays than the spineboard. The Pharaoh mattress provides similar restriction of cervical movement compared with headblocks strapped to a spineboard but with lower interface pressures and increased comfort. This new mattress could be useful for immobilization of the cervical spine in critical care patients with mechanically instable spinal fractures.

Comparing the Efficacy of Methods for Immobilizing the Thoracic-Lumbar Spine

OBJECTIVE

The purpose of this study was to compare the relative efficacy of immobilization systems in limiting thoracic-lumbar movements.

METHODS

A dynamic simulation system was used to reproduce transport-related shocks and vibration, and involuntary movements of the thoracic-lumbar region were measured using 3 immobilization configurations.

RESULTS

The vacuum mattress and the long spine board were generally more effective than the cot alone in reducing thoracic-lumbar rotation and flexion/extension. However, the vacuum mattress reduced these thoracic-lumbar movements to a greater extent than the long spine board. In addition, the vacuum mattress significantly decreased thoracic-lumbar lateral movement relative to the cot alone under all simulated transport conditions. In contrast, the long spine board allowed greater lateral movement than the cot alone in a number of the simulated transport rides.

CONCLUSION

Under the study conditions, the vacuum mattress was more effective for limiting involuntary movements of the thoracic-lumbar region than the long spine board. Moreover, the increased lateral bend observed with the long spine board under some conditions suggests it may be inadequate for immobilizing this anatomic region as presently designed. Should emergency medical service providers choose to immobilize patients with suspected injuries of the thoracic-lumbar spine, study results support the use of the vacuum mattress.

Redesign of a spine board: Proof of concept evaluation

Sacral pressure ulcers are a significant problem in individuals following spinal cord injury (SCI) and are felt to be in part due to the high interface-pressures applied to the body while lying on a standard spine board (SSB) during emergency transport. The aim of the present study was to assess the interface pressures and sensing areas between the body and the SSB and two proof of concept spine board prototypes (P-1 and P-2). Ten able-bodied individuals were assessed on each board. Interface pressures and sensing area were recorded every minute over 15 minutes. The highest pressure was generated at the sacral-iliac region. The mean of the peak pressures on the SSB, P-1, and P-2 was 288.6, 202.8, and 102.8 mmHg, respectively. The mean of the sensing areas on the SSB, P-1, and P-2 was 78.2, 98.5, and 109.4 in(2), respectively. An analysis using pairwise comparisons test showed the interface pressures were significantly reduced (p = 0.003) and the sensing area was significantly increased (p < 0.001) on P-2 in the sacral-iliac location. This study's procedures can be used when determining critical factors to guide the redesign of an SSB that reduces interface pressure and increases sensing area.

Comparison of the Vacuum Mattress versus the Spine Board Alone for Immobilization of the Cervical Spine Injured Patient: A Biomechanical Cadaveric Study

STUDY DESIGN

A biomechanical cadaveric study.

OBJECTIVE

We sought to determine the amount of motion generated in an unstable cervical spine fracture with use of the vacuum mattress versus the spine board alone. Our hypothesis is that the vacuum mattress will better immobilize an unstable cervical fracture.

SUMMARY OF BACKGROUND DATA

Trauma patients in the United States are immobilized on a rigid spine board, whereas in many other places, vacuum mattresses are used with the proposed advantages of improved comfort and better immobilization of the spine.

METHODS

Unstable subaxial cervical injuries were surgically created in five fresh whole human cadavers. The amount of motion at the injured motion segment during testing was measured using a Fastrak, three-dimensional, electromagnetic motion analysis device (Polhemus Inc.). The measurements recorded in this investigation included maximum displacements during application and removal of the device, while tilting to 90°, during a bed transfer, and a lift onto a gurney. Linear and angular displacements were compared using the Generalized Linear Model analysis of variance for repeated measures for each of the six dependent variables (three planes of angulations and three axes of displacement).

RESULTS

There was more motion in all six planes of motion during the application process with use of the spine board alone, and this was statistically significant for axial rotation (P = 0.011), axial distraction (P = 0.035), medial-lateral translation (P = 0.027), and anteroposterior translation (P = 0.026). During tilting, there was more motion with just the spine board, but this was only statistically significant for anteroposterior translation (P = 0.033). With lifting onto the gurney, there was more motion with the spine board in all planes with statistical significance, except lateral bending. During the removal process, there was more motion with the spine board alone, and this was statistically significant for axial rotation (P = 0.035), lateral bending (P = 0.044), and axial distraction (P = 0.023).

CONCLUSION

There was more motion when using a spine board alone during typical maneuvers performed during early management of the spine injured patient than the vacuum mattress. There may be benefit of use of the vacuum mattress versus the spine board alone in preventing motion at an unstable, subaxial cervical spine injury.

LEVEL OF EVIDENCE

2.

Comparison of tissue-interface pressure in healthy subjects lying on two trauma splinting devices: The vacuum mattress splint and long spine board

BACKGROUND

Most emergency transport protocols in the United States currently call for the use of a spine board (SB) to help immobilize the trauma patient. However, there are concerns that their use is associated with a risk of pressure ulcer development. An alternative device, the vacuum mattress splint (VMS) has been shown by previous investigations to be a viable alternative to the SB, but no single study has explicated the tissue-interface pressure in depth.

METHODS

To determine if the VMS will exert less pressure on areas of the body susceptible to pressure ulcers than a SB we enrolled healthy subjects to lie on the devices in random order while pressure measurements were recorded. Sensors were placed underneath the occiput, scapulae, sacrum, and heels of each subject lying on each device. Three parameters were used to analyze differences between the two devices: 1) mean pressure of all active cells, 2) number of cells exceeding 9.3kPa, and 3) maximal pressure (Pmax).

RESULTS

In all regions, there was significant reduction in the mean pressure of all active cells in the VMS. In the number of cells exceeding 9.3kPa, we saw a significant reduction in the sacrum and scapulae in the VMS, no difference in the occiput, and significantly more cells above this value in the heels of subjects on the VMS. Pmax was significantly reduced in all regions, and was less than half when examining the sacrum (104.3 vs. 41.8kPa, p<0.001).

CONCLUSION

This study does not exclude the possibility of pressure ulcer development in the VMS although there was a significant reduction in pressure in the parameters we measured in most areas. These results indicate that the VMS may reduce the incidence and severity of pressure ulcer development compared to the SB. Further prospective trials are needed to determine if these results will translate into better clinical outcomes.

The Effect of a Liner on the Dispersion of Sacral Interface Pressures During Spinal Immobilization

Sacral pressure ulcers are a significant problem following spinal cord injury and are felt to be in part due to the high interface-pressures generated while strapped to the spine board. The objective of this study was to determine sacral interface-pressure and sensing area in healthy volunteers on a spine board and the effects of a gel pressure dispersion liner. Thirty-seven volunteers were placed on a pressure-sensing mat between the subject and the spine board. Measurements were carried out with and without a gel liner. Pressures and sensing area were recorded every minute for 40 minutes. The highest pressure was generated at the sacral prominence of each subject. Mean interface-pressures were higher on the spine board alone than with the gel liner (p < .0001). Overall, mean sensing area was lower on the spine board than with the gel liner (p < .0001). Standard spinal immobilization causes high sacral interface-pressures. The addition of a gel liner on the spine board decreased overall mean sacral pressures and increased mean sensing area. Generation of sacral pressure ulcers may be related to the initial interface-pressures generated while the patient is strapped to the spine board. The addition of a gel liner may reduce the incidence of sacral pressure ulcers.

Minimal patient handling: a faculty of prehospital care consensus statement

This paper outlines the emerging best practice when packaging a prehospital trauma patient while providing spinal immobilisation. The best practice described is based on the recommendations of a consensus meeting held by the Faculty of Pre-Hospital Care, Royal College of Surgeons of Edinburgh, in the West Midlands in April 2012, where the opinion of experienced practitioners from across the prehospital and emergency care community considered the currently available evidence and reviewed current clinical practice. Initial consensus points were then subject to further review and dialogue with stakeholders from the initial meeting. The recommendations drawn from the meeting and subsequent dialogue represent a 'general agreement' to the principles and practices described in the paper. The recommendations will provide guidance for clinical practice and governance alongside other consensus statements from the Faculty of Pre-Hospital Care that seek to address prehospital spinal immobilisation and pelvic immobilisation.

The effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements

BACKGROUND

It is clinically known that shape is important when selecting or designing a wheelchair support surface for the prevention of pressure ulcers (a £ 2 billion annual cost to the National Health Service, UK); however, the effect of different levels of shape contouring has not been adequately studied.

OBJECTIVES

To investigate the effect of seat shape on the risk of pressure ulcers using discomfort and interface pressure measurements.

STUDY DESIGN

Randomised, repeated trial.

METHODS

Thirty able-bodied participants sat with restricted movement for 30 min in three sessions to evaluate two cushion shapes against a flat baseline surface. Visual Analog Scaling and pressure mapping were used to measure surrogates for pressure ulcer risk, discomfort and interface pressures, respectively.

RESULTS

Linear regression revealed a reduction in discomfort (p < 0.05) on the custom contoured shapes. Interface pressures measured were also lower (p < 0.05) on the custom contoured shapes, and a negative Pearson's correlation (p < 0.05) indicated an association between smaller hip widths and increased discomfort for the commercially shaped cushion.

CONCLUSIONS

The results of this study confirm that custom contoured shapes were effective at reducing pressure ulcer surrogate measures in the participants of this study and therefore suggests that the contribution of a cushion's three-dimensional contours on pressure ulcer risk should be further researched.

CLINICAL RELEVANCE

The measurement of seat shape, discomfort and interface pressure in surrogate participants can help inform the design of wheelchair seating for individuals who are insensate or otherwise at risk of developing pressure ulcers. This knowledge can now be implemented using modern three-dimensional shape acquisition, analysis and fabrication technologies.

Effect of vacuum spine board immobilization on incidence of pressure ulcers during evacuation of military casualties from theater

BACKGROUND CONTEXT

In the summer of 2009, the vacuum spine board (VSB) was designated by the US Air Force as the preferred method of external spinal immobilization during aeromedical transport of patients with suspected unstable thoracolumbar spine fractures. One purported advantage of the VSB is that, by distributing weight over a larger surface area, it decreases the risk of skin pressure ulceration.

PURPOSE

To examine whether the rate of pressure ulcers has changed since the introduction of the VSB.

STUDY DESIGN

Retrospective cohorts.

PATIENT SAMPLE

Injured US service members undergoing spinal immobilization during evacuation from the Iraq and Afghanistan theaters to Landstuhl, Germany.

OUTCOME MEASURES

Presence and stage of pressure ulceration, and deterioration in neurologic status.

METHODS

Records of the initial 60 patients medically evacuated on the VSB to Landstuhl Regional Medical Center were retrospectively analyzed for patient demographics, injury characteristics, and incidence of pressure injury. The incidence of pressure ulcers after the use of VSB was compared with that in a historical control consisting of 30 patients with unstable spinal injuries evacuated before the introduction of the VSB. No sources of external funding were used for this investigation.

RESULTS

The combined cohort had a mean age of 28.8 years and mean Injury Severity Score (ISS) of 20.63 and comprised 96% men. Most injury mechanisms were blunt (58%). The rate of neurological injury was 19%. There were no cases of progressive neurological deficit or deformity in either cohort. In the VSB group, using a broad definition of pressure ulcer, incidence was 13 of 60 patients (22%). Using a strict definition, incidence was eight of 60 (13%): five Stage I and three Stage II. In the non-VSB group, incidence of pressure ulcers was three of 30 (10%), using either definition, all Stage II. Difference in incidence between the groups was not statistically significant. Intubated patients had a significantly higher incidence of pressure ulcers.

CONCLUSION

Both the VSB and historic means (non-VSB) of spinal immobilization appear to be safe and produce only transient morbidity despite an average of 9 to 10 hours of transport. Intubated status was identified as the most important risk factor for the development of a pressure ulcer.

Eliminating log rolling as a spine trauma order

BACKGROUND

Currently, up to 25% of patients with spinal cord injuries may experience neurologic deterioration during the initial management of their injuries. Therefore, more effective procedures need to be established for the transportation and care of these to reduce the risk of secondary neurologic damage. Here, we present more acceptable methods to minimize motion in the unstable spine during the management of patients with traumatic spine injuries.

METHODS

This review summarizes more than a decade of research aimed at evaluating different methods of caring for patients with spine trauma.

RESULTS

The most commonly utilized technique to transport spinal cord injured patients, the log rolling maneuver, produced more motion than placing a patient on a spine board, removing a spine board, performing continuous lateral therapy, and positioning a patient prone for surgery. Alternative maneuvers that produced less motion included the straddle lift and slide, 6 + lift and slide, scoop stretcher, mechanical kinetic therapy, mechanical transfers, and the use of the operating table to rotate the patient to the prone position for surgical stabilization.

CONCLUSIONS

The log roll maneuver should be removed from the trauma response guidelines for patients with suspected spine injuries, as it creates significantly more motion in the unstable spine than the readily available alternatives. The only exception is the patient who is found prone, in which case the patient should then be log rolled directly on to the spine board utilizing a push technique.

Randomised clinical trial comparing pressure characteristics of pelvic circumferential compression devices in healthy volunteers

INTRODUCTION

The role of pelvic circumferential compression devices (PCCDs) is to temporarily stabilise a pelvic fracture, reduce the volume and tamponade the bleeding. Tissue damage may occur when PCCDs are left in place longer than a few hours. The aim of this randomised clinical trial was to quantify the pressure at the region of the greater trochanters (GTs) and the sacrum, induced by PCCDs in healthy volunteers.

MATERIALS AND METHODS

In a crossover study, the Pelvic Binder(®), SAM-Sling(®) and T-POD(®) were applied successively onto 80 healthy participants in random order. The pressure was measured using a pressure mapping system, with the volunteers in supine position on a spine board and on a hospital bed. Data were analysed using Mixed Linear Modelling.

RESULTS

On a spine board, the pressure exceeded the tissue damaging threshold at the GTs and the sacrum. Pressure at the GTs was highest with the Pelvic Binder(®), and lowest with the SAM-Sling(®). Pressure at the sacrum was highest with the Pelvic Binder(®). The pressure at the GTs and sacrum was reduced significantly for all three PCCDs upon transfer to a hospital bed.

CONCLUSION

The results of this randomised clinical trial in healthy volunteers showed that patients with pelvic fractures, temporarily stabilised with a PCCD, are at risk for developing pressure sores. The pressure on the skin exceeded the tissue damaging threshold and is, besides PCCD type, influenced by BMI, waist size and age. Regardless with which PCCD trauma patients are stabilised, early transfer from the spine board is of key importance to reduce the pressure to a level below the tissue damaging threshold. Clinicians should be aware of the potential deleterious effects associated with the application of a PCCD, and every effort must be made to remove the PCCD once haemodynamic resuscitation has been established.

Your Pillow May Not Guarantee a Good Night's Sleep or Symptom-Free Waking

PURPOSE

To describe the performance of the pillow that participants usually slept on with respect to retiring and waking cervico-thoracic symptoms, pillow comfort, and sleep quality.

METHODS

Participants (n=106) were systematically recruited for a field trial comparing their own pillow and five trial pillows. Participants provided daily retiring and waking symptom reports and sleep-quality and pillow-comfort ratings prospectively for 1 week on each pillow. Linear and logistic regression models were used to investigate the relationship between pillow use, age, gender, sleep quality, pillow comfort, and waking and temporal (overnight) symptom reports.

RESULTS

No waking symptoms were reported by 42.5% of participants on their own pillow. Regular waking symptoms, failure to relieve retiring symptoms, uncomfortable pillows, and/or poor-quality sleep were reported by over 50% of participants. All participants who reported poor sleep quality also reported poor pillow comfort. Pillow-comfort reports were not related to any waking symptom report; however, reports of poor sleep quality were significantly related to waking cervical stiffness (adjusted odds ratio [AOR]=4.3 [Confidence Interval (CI): 1.3-15.6]) and scapula pain (AOR=6.1 [CI: 1.1-31.6]). Feather pillow users provided consistently low reports of pillow comfort and sleep quality.

CONCLUSION

Many participants appear to have made poor pillow choices, as poor sleep quality, low pillow comfort, and waking symptoms were common. Further research is required to understand why people choose particular pillows to sleep on, as well as to identify the best fit between person and pillow to optimize sleep quality and reduce waking symptoms.

Immobilization and splinting in mountain rescue. Official Recommendations of the International Commission for Mountain Emergency Medicine, ICAR MEDCOM, Intended for Mountain Rescue First Responders, Physicians, and Rescue Organizations

Immobilization and splinting of fractures are essential to reduce morbidity and mortality in mountain rescue. Therefore, members of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) debated the results of a literature review carried out by the authors. Focusing on common immobilization and splinting techniques relevant to mountain rescue, a consensus document was formulated. Pain relief of appropriate speed of onset and strength should be available on scene. Spinal immobilization is recommended for all casualties that have sustained head or spine injury. The preferred method is a vacuum mattress with an appropriately sized rigid cervical collar. In such casualties, only those in an unsafe environment or with time-critical injuries should be evacuated before spinal immobilization is performed. In some casualties, the cervical spine may be cleared and a cervical collar may be omitted. In the presence of hemodynamic instability and where there is a suspicion of a fractured pelvis, an external compression splint should be applied. Splinting of a femoral shaft fracture is important to limit pain and life-threatening blood loss. If time allows, extremity fractures should be adequately splinted and, if the practitioner is skilled, a displaced fracture or joint dislocation should be reduced on scene with the use of appropriate analgesia.

Pressure ulcer risk factors in persons with SCI: Part I: Acute and rehabilitation stages

BACKGROUND

Pressure ulcers (PUs) are a common complication following a spinal-cord injury (SCI). Good prevention requires identifying the individuals at risk for developing PUs. Risk assessment scales used nowadays were designed on pathophysiological concepts and are not SCI-specific. Recently, an epidemiological approach to PU risk factors has been proposed to design an SCI-specific assessment tool. The first results seem quite disappointing, probably because of the level of evidence of the risk factors used.

OBJECTIVE

To determine PU risk factors correlated to the patients with SCI, medical care management during the acute as well as in the rehabilitation and chronic stages. This first part focuses on identifying the risk factors during the acute and rehabilitation stages.

MATERIALS AND METHODS

Systematic review of the literature.

RESULTS

Six studies met our inclusion criteria. The risk factors during the acute stage of an SCI are essentially linked to care management and treatment modalities. There is insufficient evidence to make a recommendation on medical risk factors, except for low blood pressure on admission to the Emergency Room, with a moderate level of evidence. Regarding the rehabilitation stage, no study was deemed relevant.

DISCUSSION AND CONCLUSIONS

Additional observational studies are needed, for both the acute and rehabilitation stages, to improve this level of evidence. However, this systematic review unveiled the need for a carefully assessed t care management and the related practices, especially during the acute stage of an SCI.

Development of a navigation system for minimally invasive esophagectomy

BACKGROUND

A major challenge of minimally invasive esophagectomy is the uncertainty about the exact location of the tumor and associated lymph nodes. This study aimed to develop a navigation system for visualizing surgical instruments in relation to the tumor and anatomic structures in the chest.

METHODS

An immobilization device consisting of a vacuum mattress fixed to a stretcher was built to decrease patient movement and organ deformation. Computer tomography (CT) markers were embedded in the stretcher at a defined distance to a detachable plate with optical markers on the side of the stretcher. A second plate of optical markers was fixed to the operating instrument. These two optical marker plates were tracked with an optical tracking system. Their positions were then registered in a preoperative CT data set using the authors' navigation software. This allowed a real-time visualization of the instrument and target structures. To assess the accuracy of the system, the authors designed a phantom consisting of a box containing small spheres in a specific three-dimensional layout. The positions of the spheres were first measured with the navigation system and then compared with the known real positions to determine the accuracy of the system.

RESULTS

In the accuracy assessment, the navigation system showed a precision of 0.95 +/- 0.78 mm. In a test data set, the instrument could be successfully navigated to the tumor and target structures.

CONCLUSION

The described navigation system provided real-time information about the position and orientation of the working instrument in relation to the tumor in an experimental setup. Consequently, it might improve minimally invasive esophagectomy and allow for surgical dissection in an adequate distance to the tumor margin and ease the location of affected lymph nodes.