Gunshot Injuries

Gunshot injuries occur when someone is shot by a bullet or other sort of projectile from a firearm. They vary hugely depending on anatomical location and ballistic factors.
Despite media coverage of recent gun homicides, gun crime is neither prolific nor widespread in the UK¹ and most GPs will never have to deal with firearms injuries in their entire professional lives but for anyone who does it is important to have a logical and systematic approach.

Mechanism of injury

Terminal ballistics (the study of the dynamics of bullets in gunshot injury) is a complex and difficult area. Bullets are composed of a casing enclosing an explosive powder charge, which, on striking, forces the end projectile element out at speeds of up to 1500 metres/second, dependant on the ammunition and type of gun. They inflict injury in a number of ways. Firstly, the projectile crushes structures along its track, similar to other forms of penetrating injury. Temporary cavitation causes shearing and compression, sometimes tearing structures (as with solid abdominal viscera) or stretching inelastic tissue (the brain is particularly susceptible), analogous to blunt trauma.² As tissues recoil and hot gases dissipate, soft tissue collapses inwards with the permanent cavity being the resultant defect.³ Secondly, kinetic energy transfer occurs during retardation of the bullet and this may cause damage outside the tract. Factors influencing the efficiency of kinetic energy transfer include:

• The kinetic energy of a body (e), proportional to mass and velocity (mv^²)
• Projectile's deformation and fragmentation
• Entrance profile and path travelled through the body
• Biological characteristics of the transit tissues

Projectiles tend to be classified as low velocity (<300 m/second) or high velocity (>300 m/second). Those with higher velocity may be expected, on this basis, to dissipate more energy into surrounding tissue as they slow and cause more tissue damage but this is only a very approximate guide. This 'kinetic energy dump' theory is controversial, since high velocity injuries are frequently less extensive than would be predicted and fragmentation appears to be the most effective mechanism for wounding rather than yawing or other mechanisms for slowing high velocity rounds quickly.
Interpretation of fatal gunshot wounds in post-mortem is fraught and requires expert attention.⁴

Deaths from firearms reflect their availability in various countries. Other factors must play some part - Switzerland has relatively high gun ownership and a low homicide rate (but high gun suicide rate) compared to the US.

In the year to March 2007, there were 9,608 firearm offences (most where no firearm was discharged) in England and Wales with 58 homicides (61 if air guns are included) and 413 serious injuries.⁸ In 2005-6, there were 50 fatal injuries resulting from crimes involving firearms, the lowest recorded since 1989-9 but over the same time period non-fatal injuries have more than doubled.⁹
Air guns and air rifles are potentially lethal low-velocity weapons firing lead pellet or ball bearings. They are frequently regarded more as toys rather than weapons and are thought to be owned by up to 4 million households in the UK. They generate the largest number of firearm injuries in England and Wales due to their frequent use and usually are accidental injuries to boys caused by themselves or other children. Eye, neck and abdominal injuries are most common but brain and chest trauma may also occur.¹⁰

• As with any emergency situation, first assess SAFETY - of yourself and other emergency staff - before approaching. Is the shooter still in the vicinity? Are others (including the patient) armed? Await police presence if any concerns. Routinely, paramedics and pre-hospital emergency medics wear body armour for all assault, stabbing or shooting incidents and require police back-up before entering a potentially dangerous situation.
• Employ standard trauma life support protocols for the initial assessment (Airway, Breathing, Circulation) and resuscitation - principles are the same for gunshot injuries as for any major trauma.
• When faced with gunshot wounds there are further useful questions a doctor can ask.
  • What type of weapon was used? This does not have to be make and model but a generic classification like a small handgun, a shotgun or if it was a sniper from afar it was probably a high powered rifle. The victim or witnesses may be able to answer.
  • Where is the entry wound and where is the exit wound? It is very easy to be so concerned with the entry wound that the exit wound is ignored yet it might be a larger hole.
  • What structures may have been damaged between the two? Lungs, major vessels, vascular organs like liver and kidneys or bones may be involved. If the trajectory was at an unusual angle there may be an unusual combination.

The Primary Survey

Airway

Use basic manoeuvres (suction, chin lift, oropharyngeal airway) to open an airway and apply high flow oxygen by face mask. Avoid tilting the head or moving the neck if concerns of cervical spine injury.

Breathing

Respiratory embarrassment following gunshot injury can be due to pain, flail chest, or diaphragmatic injury. Patients who are apnoeic or hypoventilating require bag and mask ventilation prior to tracheal intubation and ventilation. Insert a chest drain if there is any chance of a tear to lung, bronchus, or chest wall.

Circulation

• Make an assessment of the general state of the patient. Considerable bleeding can occur internally and hence be occult. Patients are frequently young and fit so compensate well until in extremis - tachycardia may be delayed and hypotension suggests very marked blood loss.
• If the equipment is available, get intravenous access as soon as possible.
• If possible, secure bleeding vessels. If not, compression is permissible to stem bleeding but avoid tourniquets as they may enhance distal ischaemic damage.
• In a hospital environment, get blood grouped and cross matched fast. 6 units is not an unreasonable request.
• Rapid haemorrhage may necessitate operation before adequate resuscitation but anaesthesia may induce collapse of a compromised circulation and an experienced anaesthetist is essential.

Disability

Perform a rapid assessment of neurological status.

Exposure

Clothes should be removed and the entire body surface examined for exit and entry wounds. Note, it is easy to miss these in hairy parts of the body such as the scalp, axilla and perineum.

All patients with non-trivial gunshot injuries need:

• Cross matching of 6 units of blood.
• At least one and preferably two large-bore IV cannula are required for vigorous fluid replacement. However avoid hypertension which may exacerbate blood loss - aim for a systolic BP of 100-110mmHg.
• Investigation: X-ray (AP and lateral) one body region above and one below any wound as well as the one directly involved to search for further embedded shot/bullets.
• Monitoring: vital signs; blood gases; CXR; ECG monitoring.
• Those with chest injuries may need ITU care with a chest drain to hand, and facilities for immediate thoracotomy if there is any deterioration or a cardiac arrest.

Chest injuries

• Penetration of the chest may damage pleura, lung, great vessels, heart, mediastinum, diaphragm and abdominal contents. The commonest injury is a haemopneumothorax from damage to lung and chest wall. This requires a large (adult: 32G) chest drain. Any deterioration or cardiac arrest demands prompt thoracotomy. Wounds of the intercostal vessels or heart can cause massive haemorrhage. If drainage is initially >1500ml, or >300ml/h, thoracotomy is needed.
• Sucking chest wounds must be closed immediately. Vaseline® gauze pads sealed on only 3 sides can act as a flutter valve. The seal is completed when the chest drain inserted.
• Relieve any tension pneumothorax by needling the chest on the side of the suspected lesion before inserting a 32G chest drain or doing X-rays. Delay may be fatal. A tension pneumothorax gives hyper-resonance on that side and the trachea is deviated away from it.
• Infection of war-inflicted chest wounds is a major problem. Risk is reduced by early drainage of haemothorax, wide debridement of damaged tissue, delayed closure of wounds and prolonged antibiotics.

Cardiac tamponade

• 15% of deep chest injuries involve the heart.
• Diagnosis is difficult so have a high index of suspicion following penetrating trauma:
  • Beck's triad is rising venous pressure, falling systemic pressure and a small, quiet heart but often these are not observed. Picking up muffled heart sounds at a noisy trauma scene may be impossible.
  • Pulsus paradoxus may be noted as with constrictive pericarditis.
  • The JVP may not be visible if there is hypovolaemia.
  • Pericardial aspiration is a useful diagnostic tool and may be a life-saving treatment. It also buys time before definitive anterolateral thoracotomy.
  • If the equipment is available and time permits, echocardiography is the diagnostic investigation of choice.
• To relieve a tamponade, insert an 18G needle to the left of the xiphoid. Aim at the left shoulder, but with the needle angled downwards at 45° to the horizontal.

Abdominal injuries

Abdominal injuries are associated with a high incidence of internal injury. All but the most superficial penetrating wound of the abdomen require full exploratory laparotomy. This applies as much to knife as to bullet wounds. Observation is inadequate as there may be occult bleeding or perforation of bowel. This is contended by some who feel that non-operative management of penetrating abdominal injuries of solid organs (i.e. liver, spleen or kidneys) is safe in Level 1 trauma centres, in patients who are haemodynamically stable, without signs of peritonitis, following a CT scan to rule out damage to hollow viscus organs with serial monitoring by clinical examination, haemoglobin and white cell counts.¹¹Broad-spectrum antibiotics should be administered early with any abdominal injury.

Limb injuries

Nerves, tendons and vessels are endangered, so examine the limb in a good light. Test for pulses but their presence does not exclude arterial injury. Note sensation and sweating. Any damage identified will need formal surgical repair.

Wound closure

In the past, treatment of musculo-skeletal gunshot-related injuries was dictated by whether or not the injury was caused by a low or high-velocity bullet. Increasingly, it is recognised that injuries should be assessed and treated in their entireties¹² rather than just according to the velocity of the missile since even low velocity bullets cause significant tissue damage and some high-velocity bullets (particularly those from military rifles) are designed to stay intact after impact limiting wound severity and the need for massive wound debridement.^13,14
However, many low-velocity gunshot wounds can be safely managed with local wound care and outpatient review, dependant on the absence of any bony or vascular injuries.^15,16 High velocity bullets suck foreign material (normally clothing) through both entry and exit wounds and it can be spread along dissected tissue planes, up to 30 cm from the wound tract.¹⁷ Wide excision or fasciotomy may be required to clear foreign material and dead tissue. Primary suture is frequently delayed for high velocity injuries with grafting and suture at 3-5 days.
Gunshot wounds are particularly prone to anaerobic infection, especially tetanus and gas gangrene. Ensure tetanus cover is up to date and intravenous antibiotic prophylaxis of 24-48 hours duration is usual following fractures caused by high velocity weapons or shotguns.¹⁸

Reporting gunshot injuries

GMC guidelines in 2003¹⁹ advised that doctors are responsible for informing the police of gunshot injuries arriving in an emergency department (with identification details given only by consent except in very limited circumstances). As in other instances, duty of confidentiality should be wavered where a doctor believes that they are a danger to the public.²⁰

Forensic evidence

Health care professionals also have a duty to preserve potential forensic evidence when dealing with the victims and perpetrators of violence.²¹ To this end, ensure that all the patient's clothes, belongings and any missile fragments are retained, bagged, labelled and kept secure until passed onto the police ensuring the 'chain of custody'.

Firearm and shotgun licensing

Doctors are not required to act as co-signatories or referees firearm or shotgun licenses. BMA guidance²² suggests:

• You may act as a person of 'good-standing' where the person is not a patient.
• Where the person is a patient, only support the application where you are sure that you have sufficient knowledge about the individual to justify a judgement on the individual's safety in possessing and controlling a firearm.
• In general, make it clear that you are not in a position to judge 'future dangerousness'.
• GPs may be approached by the police requesting additional information pertaining to licensing - only provide information with consent and that is relevant to the application.
• Where you believe an individual has access to a firearm and is a danger, encourage them to return their license and surrender the firearm. Breach confidence if necessary.

Air weapons

Airguns do not require a license and children under 14 years may use them if supervised by a person aged over 21 years. The government may in the future reclassify some and raise the age limit in reaction to the serious and sometimes fatal injuries they cause.

Body armour

Bullet proof jackets have considerable limitations. The protection offered is graded I to IV. By and large I and II will protect against hand guns but assault rifles and other high power weapons require ceramic tiles to give grade III or IV.²³ Like mediaeval armour they are rather heavy and cumbersome and the Americans call them 'full metal jacket'.

Gun control

Moderating the injury and death caused by the violent use of guns is a very valid public health issue. Having a gun in an American house increases the occupants' risk of a violent death in the home (whether by suicide or homicide).²⁴ The right to bear arms in the USA is enshrined in its constitution and has been ardently and effectively protected by the National Rifle Association whilst the UK has some of the strictest gun control laws in the world. The massacre of school children and their teachers in Dunblane created public horror but whilst subsequent legislation to impose even tougher restrictions on the legal owners of handguns may have captured the mood of the public it is unlikely that it saved any lives. Amnesties allowing people to hand in illegal firearms often produce impressive responses but those who hand weapons in are unlikely to use them. During the month long firearms amnesty in April 2003, over 43,000 guns were surrendered in England and Wales and 3393 in Scotland.