The literature

There are no randomised controlled trials evaluating the various out-of-hospital spinal immobilisation techniques² so it is not possible to state categorically which method(s) should and shouldn’t be used. However, certain known facts suggest that some methods may be better than others for immobilising the spine.

The UK ambulance services do not tend to use soft collars and with good reason. Soft collars do not limit movement^5,6 so are of no benefit where the risk of cervical spine injury is high. There are variances between different types of semi-rigid collars, but small studies have not demonstrated any clear reduction of movement,⁷ suggesting that the application is more important than the actual device. What has been shown on healthy volunteers is that semi-rigid cervical collars when used alone only reduce movement by between 31% and 45%,⁸ which clearly shows that a collar on its own is insufficient to protect the cervical spine. In the same study it was found that head blocks and straps produced a reduction of between 58-64% but when head blocks and straps were in place the addition of a collar was not beneficial. This is important when considering the impact of cervical collars on intracranial pressure (ICP), which is discussed later.

There has been a tendency for paramedics to routinely use long boards for the immobilisation of patients, but there may be alternatives to this approach. Long boards have been shown to be inferior to devices such as the vacuum mattress in terms of reduction of movement and patient comfort,^9,10 although the vacuum mattress is not suitable for extrication. Extrication devices such as the Kendrick extrication device (KED) have also proven to be better than long boards at reducing rotational movement and, where time is not critical, the use of such a device may be warranted.^11,12

What is essential when using a rigid long board is to minimise the time a patient is on the board. It is suggested that a patient should be on an unpadded long board for no more than 45 minutes.^13,14 The problems related to pressure ulceration are discussed later in this chapter.

A further consideration is the method used to place the patient onto the immobilisation equipment and none are without their risks. There will inevitably be a small amount of spinal movement when transferring a patient to immobilisation equipment but there appears to be little consensus as to which method should be used.

Log rolling has been shown to cause significant motion of the head and thoracolumbar spine,^15,16 although it is not known if the range of movement would actually exacerbate the clinical condition. There is a suggestion that the variation in the amount of flexion and extension between different techniques is not clinically significant¹⁷ although axial rotation appears to be more pronounced in the log-roll method than when using a 6-person lift or a lift-and-slide technique.¹⁸ Log-rolling should not be used where there is suspicion of a pelvic fracture as it may disrupt clots and promote further blood loss.¹⁹

JRCALC⁴ are suggesting that use of a scoop stretcher may be safer for lifting patients onto a long board. This is supported by research that has shown that the scoop stretcher causes significantly less movement on application compared with the long board.²⁰ It may be worth immobilising the patient on the scoop stretcher rather than transferring to a long board as this reduces the need for secondary transfers and a log-roll manoeuvre to remove the patient from the device. It has also been shown that immobilisation on the scoop provided increased comfort levels compared with the long spinal-board.²⁰

The optimum positioning for cervical immobilisation cannot be achieved without some form of padding between the back of the head and the long board. In healthy adults, a slight degree of flexion equivalent to 2 cm of occiput elevation produces a favourable increase in spinal canal/spinal cord ratio at levels C5 and C6, a region of frequent unstable spine injuries.²¹

There are numerous potential complications associated with spinal immobilisation, particularly cervical spine immobilisation using a semi-rigid collar. These include:

• Airway problems (including increased risk of aspiration)
  
• Increased intracranial pressure
  
• Restricted respiration
  
• Dysphagia
  
• Skin ulceration
  
• Pain.

Airway problems

Airway management is made more difficult in patients with suspected spinal injury by the need to maintain in-line immobilisation of the patient’s head and neck. This restricts access to the airway and also makes it more difficult to clear vomit or blood because the usual postural drainage manoeuvres may be contraindicated. Application of a semi-rigid cervical collar exacerbates the problem by significantly reducing mouth opening, which could hinder definitive airway placement.²² Loosening the cervical collar or removing the anterior portion of the collar before attempts at tracheal intubation may improve the view that can be attained during laryngoscopy.²² The flexible bougie is the preferred option for first-line use in all cases to maximise rates of intubation on first attempt.²³

The risk of aspiration is increased for the supine trauma patient. Because trauma is unexpected, the patient is likely to have a full stomach and injury may reduce their ability to protect the airway.²⁴ In the supine position, passive regurgitation or vomiting may result in aspiration of gastric contents and impaired oxygenation.²⁴ There is debate about whether the long board helps to protect against aspiration, a belief borne out by the idea that it facilitates turning a vomiting patient onto their side. It has been suggested that rapid log-rolling is considered a more appropriate strategy to turn the trauma patient that is vomiting,²⁵ but this requires four people to carry out the manoeuvre and one person to suction the patient. One person holds the head and coordinates the roll, while three others roll the chest, pelvis, and limbs so that the head, neck, body and limbs move in an aligned manner. The fifth person carefully suctions the oral cavity and avoids inducing further gagging or vomiting.²⁶ Consideration may need to be given to administration of a suitable antiemetic and gastric decompression (where trained to do so).

The use of an extrication device such as the KED may help to alleviate some of these problems by allowing the patient to be managed in a position other than supine.

Increased intracranial pressure

Correctly fitted cervical collars cause an increase in intracranial pressure,^27-31 most likely because they reduce venous return from the head. Evidence suggests that in patients with head injury, loosening of the cervical collar once the patient is securely on the board may prevent compromise of venous return and exacerbation of raised intracranial pressure.³²

Restricted respiration

Studies have shown clinically significant effects on respiration using both the long board and the vacuum mattress.³³ This is significant because restricted chest expansion can result in low tidal volumes and exacerbate the physiological effects of the supine position on respiratory function.³⁴ The supine position leads to a reduced functional residual capacity and means that fewer alveoli are available for external respiration. Given that trauma leads to an increased metabolic rate and oxygen demand, it is likely that high-concentration supplemental oxygen will be needed to help meet the patient’s oxygen requirements. These physiological effects are of particular concern where patients have associated thoracic injuries that further compromise respiratory function; it is possible that these patients will require ventilator support.

Dysphagia

Dysphagia (difficulty swallowing) has been linked to the application of a semi-rigid cervical collar but this problem has been noted specifically in patients with unusual neck anatomy following neurosurgical procedures.³⁵ It is unclear whether this may also be a problem in prehospital emergency immobilisation but it is worth bearing in mind given the potential airway obstruction that may occur as a result of dysphagia.

Skin ulceration

Cutaneous pressure ulceration is of significant concern for the spinally injured patient and every effort should be made to minimise the amount of time a patient spends on high-pressure surfaces such as the long board and scoop. The duration of contact and high interface pressure are predictors of cutaneous pressure ulceration in the trauma patient.³⁶ Ischaemia occurs when the pressure between the immobilisation device and the skin exceeds or approaches capillary pressure. At 32 mmHg of pressure, capillary blood flow becomes compromised causing hypoxia, necrosis and ulceration.³⁷ The intensity of pressure is proportional to the time necessary to cause tissue damage so that the higher the pressure, the shorter the contact time required to cause irreversible tissue damage. It is suggested that a sustained interface pressure of 35 mmHg for 2 hours and 60 mmHg for 1 hour is sufficient to cause irreversible tissue damage.³⁷ Studies on healthy subjects have recorded interface pressures of 233.5 mmHg and 82.9 mmHg at the sacrum and thorax on a rigid spine board.^34,38

Pain

Spinal immobilisation devices can induce pain, even in those with no injuries. Various studies have shown that healthy volunteers immobilised with rigid neck collars and long boards complain of pain and discomfort after approximately 30 minutes.^39,34,40 The pain is most often located at the heels, sacrum, thoracic spine, elbows, occipital region and chin where the interface pressures are at their highest.^2,34,40 It has been suggested that after 30 minutes it becomes difficult to differentiate the pain generated by the immobilisation devices from the pain caused by the initial trauma.^34,40 This will make it more difficult to assess the patient’s condition and may also lead to unnecessary clinical imaging where physicians believe the pain is related to the initial trauma.^34,40

Penetrating trauma

Until recently there has been no discrimination between blunt and penetrating trauma when considering the need for spinal immobilisation. Most books and journals have recommended that all patients with such injuries should be immobilised, or merely state that such is the practice in their emergency department and prehospital trauma care.⁴¹ However, a semi-rigid collar applied over a penetrating injury, such as high velocity bullets or projectiles, may conceal findings such as continuous oozing, subcutaneous emphysema and especially expanding haematoma.⁴¹

The recommendations from a study carried out in Israel suggest the following:⁴¹

• In penetrating injury to the neck without a clear neurological deficit, there is no place for using a collar or any other device for neck stabilisation.
  
• Neck stabilisation devices may be used when there is overt neurological deficit or the diagnosis cannot be made (i.e. unconscious victim). However, in this case it is obligatory to expose the neck by removing the anterior portion of the device every few minutes, at least in the initial phase of treatment.
  
• Neck stabilisation devices may be used for the unusual occurrence of a penetrating injury which is combined with blunt trauma. The stabilisation is then for the blunt mechanism only and not for the penetrating one.

JRCALC state that those with isolated penetrating injuries to limbs or the head do not require immobilisation. Those with truncal or neck trauma should be immobilised if the trajectory of the penetrating wound could pass near or through the spinal column.⁴

Blunt trauma

In blunt trauma, manual immobilisation should be commenced at the earliest time for any patient where the mechanism of injury suggests the possibility of SCI. The immobilisation can be released once the practitioner has ascertained that ALL of the following criteria are present:⁴

• No alteration in consciousness or mental state and patient is able to fully co-operate with examination
  
• No evidence of intoxication
  
• No complaint of spinal pain
  
• No vertebral tenderness
  
• No neurological deficit or complaint
  
• No significant distracting injury.

Note: Spinal pain does not include tenderness isolated to the muscles of the side of the neck.

• Cervical (semi-rigid) collars
  
• Extrication devices
  
• Long board and straps
  
• Vacuum mattress.

Cervical collars

There are numerous semi-rigid collars on the market and each has its own specific requirements. It is not possible to give guidance on all individual cervical collars so the practitioner should ensure that they are familiar with the techniques specific to the device being used.

A cervical spine collar needs to sit on the chest, posterior thoracic spine and clavicle, and trapezius muscle to be effective.⁴² The head is immobilised by the collar beneath the mandible and at the occiput. The spine is not fully immobilised by a collar but its application aids in reducing head movement. The sizing of the collar is also of great importance; if the collar is too small it won’t restrict the flexion motion of the neck, if too long it may cause hyperextension or allow for greater motion if the chin slips inside the front piece of the collar. In addition to sizing, it is also important to ensure that the collar is fastened correctly – too loose and it will not restrict motion of the head and neck, too tight and it may compromise the veins of the neck leading to a rise in ICP.

The collar should be applied only when the patient’s head has been brought into neutral alignment. If the head cannot be brought into neutral alignment it will be very difficult and possibly dangerous to apply a semi-rigid collar. In those instances, improvisation with blankets or towels may be required.