Prehospital Management of Vascular Injury

Principles

The extremities are the most commonly injured anatomical regions in those patients wounded on the battlefield. In patients with battlefield injury in more than one body area, 82% will have an injury to at least one limb. As a result of this, much of the guidance pertaining to management of exsanguinating extremity injury is from military experience and literature. Although caution should be used when translating experience from one sphere to another, a mangled or amputated limb caused by a motor vehicle collision or industrial accident requires similar management to that caused by an improvised explosive device (IED). Equally it should be noted that “military” mechanisms of injury can be experienced in civilian practice.

During American combat operations in Vietnam, exsanguination from wounded extremities was the most common cause of preventable death. This was in contrast to the experience of American Special Forces personnel during combat operations in Somalia in the late 1990s. Here US special forces used TQs for patients with catastrophic extremity hemorrhage, which was not standard practice during the Vietnam war or among the wider military or civilian populations in the late 1990s. Case reports from the conflict credited the use of TQs with preventing death from exsanguination. The potential value of TQ use was recognized and in the later conflicts in Iraq and Afghanistan, there was a resurgence in the use of TQs for extremity injury, along with improvements in design. The UK military were also early adopters of the new style TQs. In April 2006 they became personal issue for all UK personnel deploying to operational areas. This adoption of TQs was one part of a larger paradigm shift in care for battlefield casualties from the familiar “ABC” to a revised “<C>ABC”. This placed the control of catastrophic hemorrhage as the primary consideration when treating a wounded casualty. Reviews of the use of tourniquets, as part of this new paradigm, by both the British and American militaries again found them to be life-saving.

The UK military’s approach to the management of extremity injury was further conceptualized in a hemostatic ladder ( Fig. 5.2 ). This ladder covers the whole spectrum of the management of catastrophic hemorrhage, including in-hospital care. It should be noted that only the first four rungs on the ladder are applicable to prehospital care and, when viewed through today’s lens, the ladder could be considered to be incomplete or even incorrect due to the omission of tranexamic acid and the inclusion of recombinant activated Factor VII (rFVIIa). Notwithstanding these concerns, the principles of the hemostatic ladder remain valid and provide a good representation of the care provided to injured personnel, and remain as a guide to the management of casualties today.

A stepwise approach starting with direct pressure and elevation, using a First Field Dressing (FFD) or equivalent, is usually the first technique that should be used in the management of bleeding extremity injuries. If necessary, this can then be followed by the use of hemostatic agents (see later). If these measures fail to control hemorrhage, a TQ should then be applied.

In addition to allowing easy conceptualization of the principles of management of catastrophic hemorrhage, there are other great strengths to this model. First, there is an acknowledgement that there are times when the stepwise approach advocated should not be followed. One example is during “care under fire” (CUF) when a TQ should be applied immediately due to the tactical situation. However, it can be extrapolated that there are also clinical situations where moving straight to TQ application may be appropriate. This may be due to the state of the limb itself, i.e., mangled or amputated with catastrophic hemorrhage, or due to competing priorities in the care of the patient, e.g., concomitant airway obstruction or complete ventilatory failure requiring emergency management. In other words, there are occasions when the use of a TQ is the most expeditious way to manage exsanguination and thus should be used in order to allow timely management of other injuries, even if a more time-consuming approach, such as direct pressure with or without hemostatic gauze, may also work.

This is a situation where expert clinical judgement is required. Another example of when it may be advisable to jump some rungs of the ladder is if the number of patients outmatches the number of clinicians available to deal with them – the National Ambulance Resilience Unit recommends the use of TQs to manage extremity hemorrhage in a major incident. The final situation where TQ use is appropriate, without escalating through the hemostatic ladder, is when operating in a chemical, biological, radiological, or nuclear (CBRN) environment. Here the requirement to keep the casualty as well protected as possible from the CBRN hazard, as well as the encumbrance for the clinician of operating in personal protective equipment (PPE), necessitates the use of TQs.

In addition, the decision to use a TQ should be reviewed at the earliest appropriate point and de-escalated back down the hemostatic ladder if appropriate.

Practicalities

Simple measures often save lives. Direct pressure can often stop significant bleeding, at least until a more definitive means of controlling the bleeding is possible. If simple direct pressure is not successful, hemostatic dressings should be considered. This is likely to be especially helpful in situations where there is a wound cavity to pack, e.g., a gunshot wound. UK military guidelines suggest a two-person approach to the application of their hemostatic dressing of choice (Celox). One person removes the FFD, which was applied in order to manage the wound with direct pressure, as the other tightly packs the hemostatic dressing into the wound cavity. The first operator then reapplies direct pressure through another FFD for three minutes. The direct pressure here is key: the hemostatic dressing should be seen as an adjunct to direct pressure, not as an alternative. Further discussion about hemostatic dressings can be found below in the “Junctional Hemorrhage” section.

As discussed previously, TQs have been shown to be life-saving. Whereas the manner of application depends on the exact model of TQ used, certain principles are ubiquitous ( Box 5.1 ).

When TQs are applied for the correct indication, the risk of ischemic injury to the limb is outweighed by the risk of death from exsanguination. It should be noted that arterial TQs are routinely used in elective surgery. It should also be noted that injury to the limb is rare if a TQ is in place for less than 2 hours, although this evidence relates to elective surgical patients and may not be applicable to hypovolemic trauma patients. Application of a TQ for longer than 6 hours is likely to lead to muscle damage necessitating amputation.

Appropriate removal of a TQ is another area for consideration – see Box 5.2 for the key principles. If the TQ has been in place for more than 6 hours, removal should only be undertaken with cardiac monitoring and with appropriate equipment for resuscitation to hand.

Principles

Junctional hemorrhage, or bleeding from a junction between the torso and the extremities, is by definition not amenable to traditional extremity TQ use. This is either because it is not possible to get proximal to the wound in order to apply a TQ (in the axillae and groins) or because an ischemic zone distal to the TQ is not feasible (in the neck). Once again much of the data and experience related to the management of injuries to these areas comes from military evidence and experience. A review of US fatalities during Operations IRAQI FREEDOM (OIF) and ENDURING FREEDOM (OEF) found that by the end of OEF junctional hemorrhage had surpassed extremity hemorrhage as the leading cause of potentially avoidable death from compressible hemorrhage. These deaths are avoidable because, although not amenable to TQ use, bleeding in junctional areas is easily accessible and potentially compressible. Therefore, relatively straightforward treatment options, which can be employed by nonspecialist physicians and, indeed, by nonvocational medics, exist for managing hemorrhage in these areas. This is particularly the case with the widespread adoption of hemostatic agents. The widespread use of these dressings, along with the resurgence of TQs, must be considered one of the positive legacies of these conflicts.

Practicalities in the Management of Junctional Hemorrhage

There are additional complexities in managing vascular injury in the neck. Therefore, the management of the neck will be considered separately to the management of bleeding in the axillae and groins.

Hemostatic Dressings

We have already introduced the subject of hemostatic dressings, so will now explore in more detail what these items are and examine the pros and cons of individual formulations.

Hemostatic dressings can be grouped by their mechanism of action into :

• 1.

  Those that concentrate clotting factors

• 2.

  Muco-adhesive agents

• 3.

  Procoagulant factor supplements

Factor concentrators were the original hemostatic agents. They are presented as loose or encapsulated granules and act by rapidly absorbing water, bringing platelets and clotting factors into closer contact with each other and therefore stimulating coagulation. The agent most commonly used initially was QuickClot. However, there were concerns about an exothermic reaction from the activated agent causing burns, and also concern about difficulty removing the product from the wound further along the care pathway, and so the use of this agent has declined.

Muco-adhesive agents form a seal around the bleeding site and thus encourage coagulation. These products are usually made from chitosan impregnated gauze and include Celox and HemCon.

Procoagulant factor supplements such as QuickClot Combat Gauze deliver a high local concentration of clotting factors and thus activate the coagulation cascade.

Agreed criteria that make an ideal hemostatic dressing can be found in Box 5.3 .

Three recent systematic reviews have examined the efficacy of the different types of hemostatic dressing. All were narrative reviews due to the heterogeneity of included studies, and all found that the hemostatic dressings were effective. However, evidence comparing one particular formulation to another was both scarce and contradictory.