This article will examine and critically analyse existing literature surrounding patient immobilisation following a suspected or confirmed acute neck injury. In particular, literature on the use of a cervical collar and head blocks and the use of clinician decision tools will be critically analysed. A review has been conducted using several databases: CINAHL, PubMed, SwetsWise, Cochrane, MEDLINE, Embase, and the National Research Register. Search terms included ‘cervical collars’ and ‘immobilisation’. To ensure the inclusion of the most relevant research the search timeframe was limited to 1995 to the present day.
Pre-hospital spinal immobilisation is broadly applied in patients at risk of cervical spine injury, as recommended in resuscitation guidelines such as the Advanced Trauma Life Support Student Course Manual (American College of Surgeons, 2008), Prehospital Trauma Life Support (National Association of Emergency Medical Technicians, 2010) and the UK Ambulance Services Clinical Practice Guidelines (Joint Royal Colleges Ambulance Liaison Committee, 2013). The UK incidence of spinal cord trauma is estimated as 10–15 per million people each year (Benger and Blackham, 2009). Hasler et al (2012), whose study is based on a prospective data collection of the Trauma Audit and Research Network from 1988 to 2009, found that 3.5% of 250 584 trauma patients had a resulting spinal injury after spinal cord trauma. Hasler et al (2012) used data of a substantial size, meaning the findings would be strengthened by further dissemination, such as by a patient's presenting injuries, age or mechanism of injury, to further interpret the proportion of spinal injuries incurred.
A meta-analysis study conducted by Halpern et al (2010) found 7.5% of clinically unevaluable patients had cervical spine injuries, of which 42% had associated spinal instability. Halpern et al added:
‘Quadriplegia resulting from spinal instability missed by a clearance test had enormous impacts on longevity, quality of life, and costs, overshadowing the effects of prolonged collar application, even when the incidence of quadriplegia was extremely low’ (2010: 1727).
The results produced by Halpern et al (2010) focus on patients with altered levels of consciousness, compared to Hasler et al (2012), who consider any consciousness level. This literature review found no statistical data directly comparing the percentage of patients with reduced level of consciousness and normal levels in relation to spinal injury. Perhaps this is something that could be studied further. Studies such as Stiell et al (2001) who carried out a prospective study, found that in alert and stable patients the incidence of ‘clinically important’ cervical spine injury was 1.7%, with 0.1% developing a neurological deficit. Horodyski et al (2011) argued that fully alert, stable patients should not necessarily be immobilised; the findings from studies by Hasler et al (2012) and Halpern et al (2010) appear to support the argument in principle.
The concept of pre-hospital spinal immobilisation is to restrict mobility during extrication, resuscitation and transfer to hospital (Kwan et al, 2009). Abram and Bulstrode (2010) reviewed existing evidence suggesting that the practice of immobilisation was developed largely without robust supporting evidence, further adding that it may in fact be harmful to the patient. This suggestion is supported by McHugh and Taylor (1998) who carried out a prospective study of 129 patients over the age of 16 years with full spinal immobilisation. The results showed a statistical decrease in the number of patients that were asymptomatic following immobilisation; in addition, no patient that complained of pain agreed that it disappeared following immobilisation. Many asymptomatic patients protested at being immobilised, and they were told by the clinician it was precautionary, policy or mandatory. Finally, 13.2% of participants said they were not asked about the presence of neck or back pain prior to immobilisation. As with many studies found in this review, the sample size of this study is small; however, the advantage of a prospective study method is the sample could be widened and the study replicated to strengthen the findings. The opinions of 129 patients cannot accurately represent a wider population. Variations of patients' age, size, shape, and co-morbidities, for example, need to be considered. Also, the length of time the patient spends immobilised whilst being transferred to hospital will vary greatly; this study does not state the demographic of participants to allow the findings to be generalised.
Domeier et al (1997) carried out a retrospective chart review of patients and found that none of the 346 analysed patients suffered a cervical fracture without having at least one of the five following signs:
Domeier et al (1997) concluded the absence of all these criteria could be used to identify patients not requiring spinal immobilisation. Domeier et al (1997) make a substantial claim; however, the findings are based on 346 patients in 1992/93, it is doubtful that these findings could be substantiated enough to effect practice without further large scale research. The fragility of spinal injury and potential harm to the patient limits what alternative research methods, such as trials, could be carried out on live and healthy patients. However, alternative methods could be tested to strengthen the claims made by Domeier et al (1997), such as nationalised prospective and retrospective data collection (Kwan et al, 2009).
Hauswald et al (1998) found in a retrospective study of the effect of emergency immobilisation on neurologic outcome of patients who have blunt traumatic spinal injuries in two university hospitals, that immobilisation subjects most patients to expensive, painful, and potentially harmful treatment for little, if any benefit. The limitation of this study, however, is the two hospitals are in different countries with differing medical and economic climates. Every patient that experienced blunt trauma taken to one hospital received pre-hospital immobilisation, whereas in the other hospital no patient received immobilisation as there was essentially no emergency service. Even though the two groups may not be equivalent, the findings of this study are striking and potentially raise a question about current pre-hospital practice. However, the fact that Hauswald et al (1998) did not specify the mechanism of injury or the type of fractures presented, and that patient groups were not matched for the severity of injury, should be considered. As with Domeier et al (1997) the study size is small; it is unlikely a study group of 450 patients from two very different countries has a robust foundation to detect a statistical difference. Despite the limitations of this study the theoretical idea of immobilisation based on the concern that a conscious patient may deteriorate neurologically appears questionable. Hauswald et al (1997) found significant further force is required to cause damage, adding tissues and ligaments will generally stiffen or spasm following the initial impact and actually increase spinal stability. This review showed no studies examining the force required to create such injuries, this would be ethically and morally impractible to use live healthy patients, perhaps studies using cadavers such as that by Horodyski et al (2011) could be developed further.
The effectiveness of cervical collars and head blocks have been the subject of studies such as that conducted by Holla (2012), who carried out a proof of principle study analysing the range of movement with the addition of a rigid collar and head blocks. The study used 10 healthy subjects with different body types. Subjects were firstly tested using a rigid collar, and then head blocks, then a combination of both. The range of motion without an immobiliser was considered to be 100%. The subjects were also asked to open their mouths as far as possible once the immobilisers were applied. The results found that the mean range of motion was reduced with a collar to 34%. Head blocks reduced motion to 12%, and the combination of collar and blocks showed no mean statistical difference. Holla (2012) concluded, based on the findings of this study and a review of previous research, that rigid collars in conjunction with head blocks resulted in no additional immobilisation. Limitations for the study include the sample size, which for a quantitative study is small (Parahoo, 2006). Holla (2012) justified the sample size, arguing that the findings are so conclusive that increasing the number of healthy subjects would not affect the outcome. Furthermore, Holla (2012) acknowledges that a large-scale prospective trial of injured patients is needed. As well as there not being injured subjects included in this study, no obese or short subjects were used. This limits the generalisability of the findings would not be transferable to all patient groups.
Holla (2012) found the range of mouth opening whilst wearing a cervical collar was significantly reduced. Although the aim of a cervical collar is to restrict movement, limiting the range that a patient's mouth can be opened by using a cervical collar will have a considerable impact on patient experience and more importantly outcome. The removal of blood and/or foreign bodies, and the use of airway adjuncts would be challenging (Kwan et al, 2009; Holla, 2012). The benefit of immobilisation versus the limitation of airway management is not considered in this study, similarly no evidence was found establishing how high the risk is to the patient's airway. However, diagnosing an unstable spinal injury can be challenging, Holla (2012) argues that spinal column injury should be presumed until it can be excluded, stating that spinal immobilisation is a priority in multiple trauma, spinal clearance is not.
A similar study conducted by Horodyski et al (2011) examined the extent to which the cervical spine is immobilised. The study used a repeated-measures design to quantify motion of five lightly embalmed cadavers, assessing a one piece extrication collar, followed by a two piece collar and no collar. The study concluded neither collar was effective in significantly reducing segmental motion. As expected, there was significantly more motion with no collar. Horodyski et al.(2011) concluded that a cervical collar is better than no immobilisation but further study is required to develop an effective immobilisation technique. Horodyski et al (2011) argued, however, that immobilisation provides an important warning to clinicians to exercise caution when moving and handling a patient. This study is limited by the fact it only examines a single scenario, a global cervical instability; the need for further study is identified for upper level cervical injuries. A further limitation of this study is the use of cadavers as this will have a limited ability to accurately reflect live patients; the natural stabilising effect of muscles and ligaments is negated.
Immobilisation has associated risks, the most severe being aspiration and respiratory compromise. Asphyxiation is a major cause of preventable death in trauma (Kwan et al, 2009). Unwarranted immobilisation may cause avoidable harm; future study should consider this (Butman et al, 1996 cited by Kwan et al, 2009). It is important to consider the risk of vomiting, and consequently of pulmonary aspiration, whilst transporting the patient; managing an airway with a patient restrained in the supine position is at best challenging and potentially harmful (Benger and Blackham, 2009).
A large scale observational study was conducted by Hoffman et al (2000) who examined clinicians' decision making in spinal immobilisation. The study population consisted of 34 069 patients considered for imaging following blunt trauma in the USA. Hoffman et al (2000) identified a disproportionate number of patients that were immobilised and X-rayed unnecessarily, the main reason being the clinician's fear of litigation following misdiagnosis. The adoption of a quantitative observational study method as chosen in this study may be limiting, as this study does not address the clinician's rationale and could be strengthened by utilising a mixed method approach. A qualitative exploration of clinicians' opinion would provide a valuable insight into why the conservative approach is often taken. No research of this nature was found during this literature review, the lack of qualitative findings in this review may be due to quantitative evidence commonly being preferred in health care (Walker, 2005).
There are a number of studies, such as Domeier et al (1997), supporting the argument that the decision to immobilise a patient is disproportionate to the number of patients that have acquired a cervical injury (Hauswald et al, 1998; Orledge and Pepe, 1998; Hoffman et al, 2000; Rethnam et al, 2008; Kwan et al, 2009). Future development of a decision instrument and a spinal clearance algorithm, such as the Canadian C-spine Rule or the National Emergency X-Radiography Utilisation Study (NEXUS), could have significant value.
A retrospective study conducted by Rethnam et al (2008) reviewed 114 alert and stable patients in two hospitals; the study found two out of the 144 patients had cervical spinal injuries, both of which would have been identified when the Canadian C-Spine Rule was applied. Although this is a relatively small sample size, this study could be easily replicated and widened to national patient data, thus strengthening the findings. Rethnam et al (2008) appears to demonstrate the importance of a decision tool in reducing patient exposure to unnecessary radiation from X-ray and reduces health care costs.
Mower and Hoffman (2004) carried out a comparative review of the Canadian C-Spine Rule and NEXUS decision instrument. The study identified shared strengths and weaknesses of both methods—essentially both methods are efficient in identifying patients who do not require immobilisation and imagery. However, Mower and Hoffman (2004) state the tools are not efficient at determining patients who actually have a cervical spinal injury, which is arguably the point of a tool such as this. With this in mind, the decision instruments should not be discounted; both tools apply to blunt trauma and can aid clinical assessment of patients considered to be at low risk of spinal injury. Ultimately, both decision tools will result in a large portion of injured patients being immobilised but would generate a significant reduction in cervical spine imaging (Mower and Hoffman, 2004). A similar cohort study by Vaillancourt et al (2011) with paramedics from one emergency service looked at 3 000 consecutive, alert and stable adult trauma patients. The study found 40% of the patients could be transferred safely without immobilisation if the Canada C-Spine Rule was used.
Conclusions
Current practice of spinal immobilisation appears to be based heavily on historical practice rather than scientific precedence. Evidence shows that it is common practice to immobilise patients, yet studies demonstrating the benefit of this is limited. The decision made by the clinician to immobilise a patient is based on fear of reprisal, caution and ritualised practice rather than robust clinical assessment or a definitive criteria. A global, standardised criteria and robust immobilisation method is yet to be established. Although there are guidelines such as Canada C-spine Rule, this is an area where further study is required. An apparent lack of level one research such as large scale clinical trials showing the exact effect of pre-hospital spinal immobilisation on mortality, neurological injury and spinal injury remains uncertain.
The evidence examined in this literature review has not produced a conclusive finding of best practice. Greater consideration could be given to the patient experience, and the associated risks of immobilisation should be carefully taken into account prior to immobilisation. The risk of asphyxiation and complicated airway management in particular is concerning, and the contribution to trauma mortality cannot as such be excluded.