Article Text
Abstract
Background All trauma patients with a cervical spinal column injury or with a mechanism of injury with the potential to cause cervical spinal injury should be immobilised until a spinal injury is excluded. Immobilisation of the entire patient with a rigid cervical collar, backboard, head blocks with tape or straps is recommended by the Advanced Trauma Life Support guidelines. However there is insufficient evidence to support these guidelines.
Objective To analyse the effects on the range of motion of the addition of a rigid collar to head blocks strapped on a backboard.
Method The active range of motion of the cervical spine was determined by computerised digital dual inclinometry, in 10 healthy volunteers with a rigid collar, head blocks strapped on a padded spine board and a combination of both. Maximal opening of the mouth with all types of immobiliser in place was also measured.
Results The addition of a rigid collar to head blocks strapped on a spine board did not result in extra immobilisation of the cervical spine. Opening of the mouth was significantly reduced in patients with a rigid collar.
Conclusion Based on this proof of principle study and other previous evidence of adverse effects of rigid collars, the addition of a rigid collar to head blocks is considered unnecessary and potentially dangerous. Therefore the use of this combination of cervical spine immobilisers must be reconsidered.
- Neurology
- spinal
- nursing
- prehospital
- nursing
- emergency departments
- trauma
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Introduction
All trauma patients with a cervical spinal column injury or with a mechanism of injury having the potential to cause cervical spinal injury should be immobilised at the scene, during transport and in hospital, until a spinal injury is excluded.1 2 Immobilisation of the entire spine with a rigid cervical collar, head immobilisation, backboard, tape and straps is recommended in the Advanced Trauma Life Support guidelines by the American College of Surgeons.2 More than five million patients require spinal immobilisation each year.3 From a trial in 1983 it was concluded that the combination of a rigid collar with sandbags and tape was most effective in immobilisation of the cervical spine.4 In the 1990s, the sandbags and tape were replaced by foam head blocks strapped to padded backboards. The combination of a rigid collar with foam head blocks strapped on a backboard is now commonly used world wide. The rationale for this technique is that two different immobilisers probably result in better immobilisation and are therefore safer. However, there is insufficient evidence to support these guidelines.2 No scientific reports have been published about this method of double immobilisation. In this study the effects on the range of motion of the addition of a rigid collar to head blocks strapped on a backboard were analysed.
Materials and methods
For the rigid collar we used the Select Stifneck collar (Laerdal Medical Corp, Wappingers Falls, New York, USA), which is made of a hard polyethylene shell that can be closed with a Velcro band. It is padded with a 2 mm layer of soft foam. The collar immobilises the cervical spine by bridging the sternum, clavicles, trapezoidal muscles and upper back to the occipital bone and mandible. The collar was used according to the manufacturer's instructions.
Sof-Loc head blocks ((#35993 Iron Duck, Chicopee, Massachusetts, USA) were used. These two vinyl-dipped foam blocks were strapped with two Velcro straps on both sides of the head to a padded spine board (Traumatras, Almelo, the Netherlands). The skull and head blocks were fixed directly to the spine board, which in turn was connected to the thorax with straps.
Ten healthy subjects with different body types, as described in table 1, were selected to test the rigid collar, the head blocks strapped on the backboard and the combination of both. The volunteers were asked to flex, extend, laterally bend and rotate their head as much as possible with the different immobilisers on, as shown in figure 1. The range of motion was measured with a computerised digital inclinometer (EDI 320 CYBEX, Ronkonkoma, New York, USA) as described by the American Medical Association.5
The range of motion without an immobiliser was considered 100% of the normal range of motion.
The same volunteers were asked to open their mouth as far as possible with and without application of the immobilisers. The distance from the lower border of the upper incisors and the upper border of the lower incisors was measured three times with a ruler as described by Chin et al,6 and the average calculated.
The mean active range of motion and SD was determined for each immobilising technique. A two-tailed paired Student t test and 95% confidence interval was calculated using SPSS 16.
Results
The range of motion of the cervical spine with and without cervical immobilisation is presented in figure 2 and table 2. With the rigid collar on, the mean range of motion in all directions was limited to at least 34% of the normal range of motion. With the head blocks alone the mean range of motion was reduced to at least 12% of the normal range of motion. The range of motion in all directions was not reduced with the addition of a rigid collar to head blocks.
As described in table 3, the difference in the range of motion was significant reduced (p<0.005) by the collar compared with no immobilisation. A second significant decrease (p<0.005) in the range of motion in all directions was seen when the head blocks were compared with the rigid collar. No significant decrease (p>0.05) in the range of motion was observed when the collar was added to the head blocks.
The mean mouth opening was significant reduced (p<0.01) from 47 mm (SD 9 mm) without a collar to 34 mm (SD 11 mm) with a collar.
Discussion
This proof of principle study demonstrates that the application of a rigid collar in addition to head blocks does not provide extra immobilisation of the cervical spine. No previous reports showing benefit of this combination of immobilisation are available. Nonetheless, this combination has been used world wide on millions of patients.3
It is well known that most commonly used collars do not fully immobilise the cervical spine.7 8 At least 19° of flexion-extension, 46° of axial rotation, or 45° of lateral bending is possible with different collars.8 Other rigid collars like the Aspen, Ambu and Miami J-collar function in a similar manner.9
The use of sandbags and tape was more effective in immobilisation of the cervical spine than any collar.4 The addition of a Philadelphia collar to sandbags reduced the extension from 15° to 7°. Although the range of motion was measured with a hand-held goniometer and no significance analysis was reported in that study, the combination of a collar and sandbags with tape was previously advised.4 However, the modern foam head blocks strapped to a spine board, as used in this study, limit all cervical motions, including extension to <15°. Therefore it is clear that the semi-constraining rigid collars do not add extra immobilisation to full-constraining head blocks. The assumption that a combination of two different immobilisers results in the best immobilisation is not true.
The number of subjects in this study is limited. After evaluation of a pilot study of 10 subjects, however, it became obvious that the best cervical immobiliser determines the range of motion of the cervical spine. Therefore it is not likely that increasing the number of healthy volunteers in this proof of principle, will affect the outcome of this study. However, a larger prospective trial with injured patients is needed.
No extremely obese, short or injured subjects were included in this study. It is unknown if, and how, the range of motion is affected by external immobilisers in these groups of patients. Further prospective clinical trials are needed to answer these questions.
Although the reliability for the range of motion for inclinometry is rated good, with an intraobserver and interobserver intraclass correlation coefficient of 0.85, 0.70, respectively, the smallest detectable differences with the Cybex EDI-320 go up to 10° for flexion-extension, 7° for lateral flexion and 14° for rotation.10 However, despite the 95% CIs of this study, these measurement errors will not affect the clinical message of the study: a rigid collar does not provide additional immobilisation when used in combination with head blocks.
In agreement with other studies we found that the use of a rigid collar significantly reduces mouth opening.11 12 All rigid collars immobilise the cervical spine by compression of the mandible. This forces the mandible upwards to close the mouth. If less pressure is applied to the mandible to increase the mouth opening more movement is possible in the cervical spine. Limited mouth opening will make removal of blood, broken teeth or artificial dentures and placing a tracheal tube more difficult. Some tubes cannot be placed when a rigid collar is in place.13
Apart from a lack of additional immobilisation and a limitation of the opening of the mouth a number of adverse side effect of rigid collars are described in the literature, as discussed in the following sections.2
Increased motion in the high cervical spine
The pressure of the collar on the mandible forces the skull to tilt backwards when the mouth is opened. A fluoroscopic study with chewing healthy people showed an increased motion at the higher levels of the cervical spine when wearing a rigid collar.6 As upper cervical spine fractures occur relatively frequently, complete immobilisation of the total cervical spine is needed in patients with possible instability of the spine.14
Pressure sores of the skin
With rigid collars like the Stifneck, local pressures on the skin go up to 80 mm Hg.15 This can cause collar-related decubitis ulcerations.15–20 Pressure sores can complicate later surgery and make later immobilisation with an orthosis impossible.
Increased intracranial pressure
A rigid collar can act like a cervical tourniquet, since it compresses the jugular veins with interface pressures of >10 mm Hg.21 Several studies describe an increase of intracranial pressure due to rigid collars.22–26 Because trauma patients, especially those with cervical injuries, often have intracranial contusions,14 27 it is clinically relevant to keep the intracranial pressure as low as possible.23
Increased pain and discomfort
As rigid collars rests upon the clavicles, sternum and upper ribs, fractures in this area will cause additional pain. Furthermore, a rigid collar can cause pain in an otherwise healthy subject.28 The examining doctor can misinterpret this as pain from a cervical spinal injury.29
Difficulty in obtaining adequate radiographs
It is not possible to make an odontoid peg radiograph with a rigid collar on because the mouth cannot be fully opened. Temporary removal of the collar leads to extra manipulations and is time consuming. Furthermore, rigid collars are not completely radiolucent. The contrast of the image will decrease, and misleading distortions can occur at the edges of the collar.
False sense of full immobilisation
Complete immobilisation by a rigid collar is impossible because it rests on the mobile shoulder girdles and mobile mandible. A false sense of security that the cervical spine is fully immobilised with a rigid collar can be created.30 Manual support of the head by an experienced person is always needed when a patient is log rolled with only a rigid cervical collar on.
The adverse effects of rigid collars are summarised in figure 3.
One might argue that a rigid collar may work as a reminder to the trauma team that the cervical spine is not cleared for instability. The head blocks, however, can work as a similar reminder.
The rigid collar can be useful in temporary immobilisation of the neck at extrication of patients in a sitting position in cars. However, based on the results of this study, the rigid collar should be removed when the head blocks are placed.
Conclusion
The results of this proof of principle study demonstrate that the addition of a rigid collar to head blocks does not provide any extra immobilisation of the cervical spine and is therefore considered unnecessary. Furthermore, this study showed that a rigid collar reduces the ability to open the mouth and clear the airway. In view of this and other known adverse effects of a rigid collar (increased motion at the level of the high cervical spine, increased intracranial pressures, pressure sores of the skin, increased pain and discomfort, poor quality of radiographs and a false sense of immobilisation), the combination of a rigid collar and head blocks should be reconsidered.
References
Footnotes
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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