Table 2 Reviewed articles for jugular vein dimension and intracranial pressure (ICP)

Craig et al., 1991 [25]

UK

Case review:

Intracranial pressure and collar use

Collar use was associated with impaired venous drainage and as such relates to an increase in ICP

Only two patients

2 patients

Lemyze et al., 2011 [28]

France

Case review:

Level of consciousness

Collar use post hanging may exacerbate cerebral oedema due to compression of neck veins

Only one patient

1 patient

Dunham et al., 2008 [32]

USA

Literature Review

Risks with MRI and collar use

Collar use is associated with a rise in ICP, and secondary brain injury; early collar removal advocated

Evidence supports the theory but no substantial proof

Ho et al., 2002 [7]

China

Literature Review

Intracranial pressure and collar use

Collars appear to act like a tourniquet around the neck, potentially exacerbating a head injury and increasing ICP

Evidence supports the theory but no substantial proof

Dunham et al., 2011 [8]

USA

Simulation study

Collar use and outcome

Early collar removal is advocated for unstable/high risk and stable patients with spinal injuries

Simulation study only; no real proof for claims

Davies et al., 1996 [6]

UK

Study:

ICP before and after collar application

Stifneck collar may cause a rise in intracranial pressure.

Supports hypothesis for collars affecting ICP but exact mechanism for rise in ICP was not determined

19 patients

Hunt et al., 2001 [29]

UK

Study:

ICP before and after collar application

Collars are associated with a rise in intracranial pressure, potentially worse if the ICP is higher to start with

Supports hypothesis for collars affecting ICP but exact mechanism for rise in ICP was not determined

30 patients

Kolb et al., 1999 [24]

USA

Study:

Cerebrospinal fluid pressure before and after collar application

Cerebrospinal fluid pressure increased after collar application, but no clear associated with BMI

Collars were placed when the patient was inclined to the side rather than supine; exact mechanism for rise in ICP was not determined

20 patients

Kuhnigk et al., 1993 [30]

Germany

Study:

Intracranial pressure and collar use

Found no correlation between collar use and increased intracranial pressure

Baseline ICP readings were higher than in other reports and as such may have had an impact on the results

18 patients

Mobbs et al., 2002 [9]

Australia

Study:

ICP before and after collar application

Intracranial pressure was higher following the application of a collar

Supports hypothesis for collars affecting ICP but exact mechanism for rise in ICP was not determined

10 patients

Stone et al., 2010 [31]

USA

Study:

Jugular vein dimensions before and after collar application

Collar application associated with alteration to jugular vein diameter indicative of venous obstruction

Supports hypothesis for collars affecting ICP but no mechanism was determined as actual ICP was not measured

42 volunteers

Porter et al., 1999 [27]

UK

Study:

ICP before and after collar application

All patients showed a rise in ICP following collar application

Supports hypothesis for collars affecting ICP but no mechanism was determined

9 patients

Ferguson et al., 1993 [10]

UK

Study:

Tissue Interface Pressure around neck area

Normal jugular venous pressure when supine was 2-7 mmHg, concluded pressures exerted on the neck over this will cause a ‘back pressure’

Supposition rather than fact with the relationship of collar use to increased ICP

5 patients

Raphael et al., 1994 [26]

UK

Study:

Cerebrospinal fluid pressure before and after collar application

7/9 experienced raised cerebrospinal fluid pressure following collar application

Supports hypothesis for collars affecting ICP but no mechanism was determined

9 patients