Introduction
The use of tear gas as a Riot Control Agent (RCA) by law enforcement agencies has dramatically increased in recent years and is used worldwide to control riots, protests and civil unrest (Rothenburg et al 2016). It is employed in a variety of settings from refugee camps and humanitarian contexts (MSF 2016a, BBC 2016, Strickland 2015, Baumard 2016) to football match riots and state protests (Stephens 2016, Aciksoz 2015) and can present numerous challenges for the attending healthcare worker (HCW). Yet how to best manage victims exposed to tear gas is still a matter of debate (Brvar 2015). In the absence of an accepted standardised approach, the general public have adopted their own strategies for dealing with the burning sensations associated with tear gas. An example of which is demonstrated by (Aciksoz 2015) who refers to ‘emergency aid stations’ offering lemon halves, vinegar solutions and liquid antacid and water during the 2013 Gezi protests in Turkey. Nottinghamshire Police (2016) warn that some of these remedies being used are ‘mythical at best and at worst, may exacerbate the pain and length of time taken to recover’. As the eye is the most sensitive and immediately affected organ (Blain 2003) it is no surprise that it is the main focus of the first aider's efforts when attending to tear gas victims. ‘First do no harm’ is a concept that all medical professionals will be familiar with and so it is reasonable to expect that we have a knowledge of the types of treatment used by the general public in order to promote and to practice safe medicine. This paper will therefore investigate some of the general public's more popular treatments alongside available academic literature in order to critically explore best practice for ocular management post exposure to tear gas.
Background:
‘Tear gas’ is an umbrella term for various agents such as oleoresin capsicum (OC) and 2-Chloroacetophenone (CN), more commonly known as ‘Pepper spray’ and ‘Mace’ respectively (Schep et al. 2013). Another, o-chlorobenzylidene malonitrile, came to be known as ‘CS gas’, named after the American Chemists Corson and Stoughton who first synthesized it in 1928 (Sivathasan 2010). These gases are also referred to by terms such as Riot Control Agents, lacrimators and incapacitating agents (Schep, Slaughter and McBride 2013, Sivathasan 2010). CS is the tear gas most commonly and most widely used (Brvar 2015, Rothenberg et al. 2016, Sivathasan 2010) and so will be the focus of treatment when referring to ‘tear gas’ in this essay.
CS gas reacts with the moisture on the mucous membranes and irritates the eyes, nose, mouth, skin, and respiratory tract (Schep, Slaughter and McBride 2013, ECHA 2016, Blain 2003). Table 1 shows a full list of the primary effects of exposure to CS gas. Ocular effects involve lacrimation, blepharospasm, photophobia, conjunctivitis and periorbital oedema (Schep, Slaughter and McBride 2013, Brvar 2015).
Literature review
It should be acknowledged that the majority of the general public will acquire their information from non-academic websites. Unfortunately, such internet searches return many examples of questionable information. These include references to ‘trials by street medics’ (Medic Wiki n.d) and confusing statements such as “tear gas is not actually a gas but a rapidly dispersing chemical agent called capsaicin” (Ferguson 2011). With the same replicated paragraphs appearing on various different websites, it is easy to see how this misinformation will spread.
Finding reliable management protocols with a sound evidence base however proves difficult. A search of the literature reveals a mixed and confusing picture. The key terms used for the literature search were tear gas, CS gas, chlorobenzylidene malonitrile, riot control agents, incapacitating agents; and the databases included: CINAHL, PubMed, Medline, Google Scholar and Google. An initial search for publications from the past 10 years revealed very few sources and therefore the timeframe was opened up to include any prominent literature dating back to 1995. The references within the chosen articles were also reviewed to identify further relevant literature. In spite of this very little literature was found to exist that treats the question specifically of ocular treatment post exposure to CS gas. This literature will now be critically discussed in relation to the ocular management of CS gas victims specifically in the pre-hospital context.
Common principles of CS gas treatment.
Whilst some treatments appear debateable, there are some common principles that should form the cornerstone of best practice treatment at all times. Moving people exposed to CS gas out of the contaminated area and into fresh, moving air is the most important initial action ensuring rapid dispersal of the spray (Schep, Slaughter and McBride 2013, Austin, Crawford and Armstrong. 2014, Brookes 2013, FFLM 2014, Worthington and Nee 1999). CS gas is heavier than air which explains why moving to higher ground is preferable wherever possible (Carron and Yersin 2009). CS gas in smoke format can cover between 60 and 300m2 (Rothenberg et al 2016). This method of gas delivery is less discriminating than a spray and so the area of contamination on the patient is likely to be greater (Nottinghamshire Police 2016). Thus, guidance for removal of clothing is more significant (Nottinghamshire Police 2016) and garments should be removed as soon as possible and sealed in a labelled plastic bag to avoid recontamination of the face or of others (Austin, Crawford and Armstrong. 2014, Brookes 2013).
Victims should avoid rubbing their eyes (McGorrigan and Payne-James 2014) as this will spread the area of contamination, raise the temperature of the skin and increase the burning sensation (Brookes 2013). Removal of contact lenses should be advised after washing and drying hands and help offered if necessary (Austin, Crawford and Armstrong 2014, McGorrigan and Payne-James 2014, Brookes 2013). Wearing glasses may be more suitable in areas that are constantly subjected to attacks by CS gas.
It is very important to reassure the individual, to let them know that the effects are temporary (Brookes 2013, McGorrigan and Payne-James 2014) and if circumstance allows, this should be done away from the noise and commotion whilst encouraging the victim to sit upright and breathe normally (Brookes 2013). Panic and agitation are common, especially on first exposure (Schep, Slaughter and McBride (2013) and stress reactions may impair the ability to communicate.
Where showering or washing is possible, National Health Service (NHS) (2011) state that the affected person should have a shower on as cold a setting as possible because hot water reactivates irritants used in CS spray. McGorrigan and Payne-James (2014) agree, warning against hot water use under any circumstances. Brvar (2015) notes that the most recommended methods for cutaneous rinsing are soap and copious flowing water since CS is sparingly soluble in water. Nottinghamshire Police (2016) goes further to advocate the use of just water and normal soap and to not bother with any other solutions or antacid type products. They advise not to isolate the eyes for irrigation rather to let a cold shower wash away the crystals. Slight controversy exists when wiping the face. Schep, Slaughter and McBride (2013) argue that this should be done before washing to remove particles whereas Nottinghamshire Police (2016) warns this runs the risk of pushing particles back into the pores.
Protecting the HCW and secondary effects
Kain, Mishra and James (2009) conclude that secondary exposure to CS gas can pose a significant risk to the HCW and Schep, Slaughter and McBride (2013) report the possibility for minor effects such as facial pruritis and respiratory and eye irritation to develop. It is essential (Carron and Yersin 2009) for HCWs to take precautions to protect against exposure from affected CS gas victims in order to enable more successful treatment. McGorrigan and Payne-James (2014) advocate the use of gloves and eye protection to avoid cross contamination and Brookes (2013) adds aprons to this list while advising practitioners with any respiratory or dermatological conditions to avoid providing care until effects of CS gas have diminished. Schep, Slaughter and McBride (2013) mention the use of goggles, gowns and surgical masks and treating in a well ventilated room.
Whilst many internet webpages will concentrate on medical treatments for their first aid kits, they may often neglect basic personal protective equipment. Table 2 shows a suggested ‘CS gas emergency pack’ that HCWs may find useful to implement.
|
|
Is medical treatment necessary for the average patient?
Médecins Sans Frontières (MSF) (2016b) referred the author to World Health Organization (WHO) guidelines for treating CS gas. Whilst CS gas is mentioned in the WHO (2014b) Guidelines for Initial Clinical Management of Patients Exposed to Chemical Weapons, specific treatment options for CS gas are not covered. Instead, a more general approach for chemical weapons exposure using the ‘Rinse-Wipe-Rinse’ technique is proposed whilst advocating copious irrigation of the eyes with 0.9% saline. The importance of this advice is not being called into question when chemical weapons are suspected but it should be asked if it is always the correct course of action in the case of CS gas. According to McGorrigan and Payne-James (2014), terminology has recently changed from ‘incapacitants’ to ‘irritants’ in order to reflect the use of CS gas as an RCA and not a chemical weapon. They suggest CS gas is an RCA because ‘the effects can be reversed without medical intervention’ and in most cases the symptoms are short lived, resolving over 15-30 minutes.
So before examining individual ocular treatments for CS gas serious consideration should be given as to whether or not treatment is necessary at all. Whilst Brvar (2015) builds a case for it being ‘evident that rinsing should commence as soon as possible’, and Schep, Slaughter and McBride (2013) call for ‘thorough eye decontamination, an eye exam and appropriate pain management’, there are also those who suggest that ‘medical treatment’ may not be necessary.
Left untreated, most symptoms will resolve within minutes of exposure (Blaho and Stark 2000). NHS (2011) describe these ‘incapacitants’ as ‘non-lethal and basically harmless.’ The Association of Chief Police Officers (2009) and Worthington and Nee (1999) tell us that most cases resolve spontaneously within 15-30 minutes once exposed to cool, fresh air and Breakell and Bodiwala (1998) echoed this sentiment, further stating that military studies endorse these first aid measures. Brvar (2016) reports that the Slovenian police force have no immediate decontamination measures when recruits are subjected to the gas and Brookes (2013) states that symptoms generally improve as effects are temporary meaning medical treatment may not be necessary. The caveat being that if symptoms do not improve within suggested time frames or pre-existing medical conditions give cause for concern, then medical attention should be sought. The Health protection Agency (HPA) (2008) stipulate a timeframe of 2 hours with persistent pain for referral to ophthalmology. ACPO (2009) declare that so-called ‘antidote’ or ‘neutralising agents’ have been tested and deemed inappropriate though they do not identify which ones.
That is not to say that exposure to CS gas cannot be dangerous. The more serious reports usually have a common theme; namely confined, unventilated spaces in which the individual may be exposed to very high concentrations of CS (Blain 2003, Dimitrogolou, Rachiotis and Hadjichristodoulou 2015). In this systematic review, Dimitroglou, Rachiotis and Hadjichristodoulou (2015) discuss longer-term ocular, dermal and respiratory health risks from CS gas as well as life threatening situations. Sivathasan (2010), McGorrigan and Payne-James (2014) and Gantly (2013) also talk of long-term health consequences. Schep, Slaughter and McBride (2013) discuss the embedding of particles in the cornea or conjunctiva after a CS gas grenade explosion necessitating slit lamp examination and removal of said particles. Wheeler and Murray (1995) refer to a case where paramedics made an incorrect differential diagnosis of CS gas where lack of treatment could have led to permanent ocular damage.
Blowing and moving dry air
It has been purported on social media (Grim 2014) that cigarette smoke when blown into the eyes alleviates the pain caused by CS gas. When questioned, Nottinghamshire Police (2016) suggest that the cigarette smoke itself used by ‘first aiders’ will do nothing and there are more effective ways of moving air such as with a fan or by the wafting of a clipboard.
Whilst no literature mentions the blowing of cigarette smoke specifically, many do refer to an air flow over the eyes, such as that directed by a fan.
Shortly after the introduction of CS gas by UK Police forces as a crowd control agent Worthington and Nee (1999) iterated the need to blow dry air directly onto the eyes resorting to water or isotonic fluids afterwards if not completely successful. Worthington and Nee (1999) like others (Grey 1995) tend to cite Yih (1995) when suggesting this method. Yih writes that doing so, the pain will reduce in minutes and warns against rinsing the eye first as this may prolong the burning sensation.
Sivthasan (2010), however, suggests Yih (1995) and other papers have somewhat inaccurately suggested blowing dry air onto affected eyes in order to facilitate vaporization of the dissolved CS gas. He explains that CS gas is essentially insoluble at normal temperatures and pressures leading to the decision that irrigation with water or saline should be started without delay. Whilst one train of thought appears to be centered around the unlikelihood of vaporization of the dissolved CS gas, another approach is to look at it from the perspective of blowing away the crystals. While natural tear secretion is usually enough to irrigate and remove the chemical from the eye (Breakell and Bodiwala 1998) it may be then necessary to ‘move the air’ to blow away the newly formed crystals (Nottinghamshire Police 2016).
Svinos and O'Malley (2011) when comparing active blown air vs. irrigation in a review of the literature concluded that either could be used to relieve eye symptoms after CS gas exposure. Breakell and Bodiwala (1998) on the other hand found that attempts to blow cold air onto the face did not result in any clinical improvement though it should be noted that the patients presented to hospital 20 minutes after exposure. They found that treatment with saline however, did improve symptoms. Whilst an unlikely issue outdoors, it was mentioned that using a fan increased contamination of the treating facility and therefore thought should be given to this when transferring patients to ambulances or to medical centres for treatment.
Irrigation with water and saline
The purpose of irrigation is to remove the chemical burden via elimination, dilution and pH neutralization (Chau Lee and Lo 2012). Brvar (2015) found that ocular rinsing with saline or water is mostly recommended and a literature review by Schep, Slaughter and McBride (2013) concluded that flushing with saline or water for 15–20 min would appear to be the most sensible initial procedure for any exposure to CS gas. Yet this advice is in stark contrast to advice from McGorrigan and Payne-James (2014) and Brookes (2013) who state that flushing with water or saline at an early stage will exacerbate symptoms or cause symptom relapse due to the rupturing of the CS crystals. They continue that saline should be used for irrigation after 60 minutes only if eye symptoms persist although its use may temporarily exacerbate the symptoms. Breakell and Bodiwala (1998) suggest waiting 30 mins before irrigating with saline.
The optimal duration for eye irrigation has not been agreed upon for chemical burns generally (Chau, Lee and Lo 2012) but it is interesting to note the time frames and quantities suggested for the treatment of CS Gas. Carron and Yersin (2009) recommend rinsing with saline for 10-15 minutes whereas others (Chau, Lee and Lo 2012, Sivathasan 2010) talk of ‘prolonged and copious’ irrigation to remove the solid particulates. For irrigation of Capsaicin Barceloux (2009) recommends at least 1-2 L of saline for eyes and skin. The advice from the Centers for Disease Control and Prevention (CDC) (2013) is to rinse with water until there is no evidence of RCAs in the eyes. Whilst this advice may be relevant in a hospital or healthcare setting, thought should be given to the quantity of fluid that the HCW may have at their disposal in the pre-hospital environment. Treatment with small vials for example would constitute neither ‘copious’ nor ‘prolonged’ and may simply increase pain (Chau, Lee and Lo 2012) by facilitating the spread and absorption of the chemical (WHO 2014b). Large amounts of saline to treat the numbers of people affected each time may not be available in such circumstances. Water, arguably, will be more accessible but is not without its own complications. The humanitarian context may prove difficult here. In reference to the Calais Jungle, the dismantled refugee camp that existed in the north of France, not only did Hands International (2015) condemn access to water as inadequate but issued reports of e-coli and salmonella in the water too. An MSF coordinator in the Jungle also reported 3 known cases of Hepatitis A (Thomson 2016). Two of the viruses that cause hepatitis (hepatitis A and E) can be transmitted by ingesting water (WHO 2014a), so caution should be exercised.
Another factor to consider with water may be the ‘wash-in effect’ (Brvar 2015). Moody and Maibach (2006) warn that washing with water, under some circumstances may increase local and systemic toxicity. When used to irrigate, water dilutes the chemical and mechanically rinses it from the eye but the hypotonicity of water relative to the eye may encourage an increased uptake of water, bringing the chemicals with it (Chau, Lee and Lo 2012, Prevor 2016). Irrigation is sometimes recommended with fluids of higher osmolarity to mobilize these chemicals out of the eye hence Blaho and Stark (2000) argue that on the rare occasions that irrigation is needed, normal saline and not water is the best choice. In their systematic review Chau, Lee and Lo (2012) conclude stating that despite obvious benefits there is insufficient evidence to recommend any rinsing options.
Whilst the UK Ambulance Services (JRCALC 2016) advise irrigating with tap water for heavy contamination of the skin and eyes, Carron and Yersin (2009) point out that CS gas dissolved in water intensifies the irritation. Furthermore, Brvar (2015) reports that in one study comparing different irrigating solutions police officers involved in the study refused to use pure water decontamination due to previous painful experiences. The need to use a topical anaesthetic to enable the patient to open their eyelids enough to allow irrigation was raised by Schep, Slaughter and McBride (2013). An unlikely option in the humanitarian context or when attending large scale protests with mass casualties.
Liquid Antacid and Water (L.A.W)
The use of L.A.W. (usually Maalox and water) is referenced by many online for the treatment of ‘tear gas’ (Temelkuran 2013, Maguire 2011, Ferguson 2011, Blackcrosscollective 2016) although it seems to have been forgotten that ‘tear gas’ is an umbrella term for various chemicals. Existing research looking at treatment with a liquid antacid has not revolved around CS gas but instead pain induced by capsaicin. Brvar (2015) and Sivathasan (2010) explain that when CS gas hydrolyses, it produces acidic metabolites including hydrochloric acid and this may be one reason why the idea of antacids remains a popular treatment.
The only reference to an evidence-based literature by online sources (Medic Wiki n.d) for L.A.W. is to a paper by Katz (2010) and this does indeed refer to topical antacid-therapy for capsaicin-induced dermal pain. Capsaicin is the crystallised active component of Chilli peppers (Barceloux 2009) and therefore is not the same chemical as CS Gas. Whilst pepper spray is used as a tear gas it is not the tear gas of choice for law enforcement agencies, as previously discussed. The Katz (2010) paper refers to 3 more reports of topical antacid therapy but these still relate uniquely to either pepper spray or mace. Furthermore, in this paper by Katz (2010) no reference is made to treating the eyes, despite being used as supporting evidence for eye irrigation by various websites. Also, the paper was based on a ‘phone-in’ survey leaving various factors unknown that could have affected antacid responsiveness. In summary though, the authors say the results support the application of topical antacids for capsaicin induced dermal pain.
In 2003, Lee et al. found a statistically significant decrease in pain with Maalox compared with Saline treatments at 10, 20 and 30 minutes after exposure (P-Value = 0.02, 0.01, 0.01 respectively). However, this study involved only 10 people and the cut off for clinical significance was deemed questionable (1.3cm using VAS scores). They concluded that it may be an appropriate treatment for dermal capsaicin exposure and are unsure as to its mechanism of action. Further studies comparing treatment regimens for Capsaicin induced dermal pain were carried out by Barry, Hennessy and McManus (2008). The results of their randomised control trial failed to show any relief provided by Maalox nor any of the other substances tested. The best predictor for a decrease in pain appears to be quite simply the time elapsed since exposure. They could therefore not make any recommendations for Maalox in practice. In fact, expert opinion (Nottinghamshire police 2016) states that Antacid based solutions are ‘pretty irrelevant and would only realistically do the same as water’.
Alternative treatments:
Lastly, various studies (Hall et al. 2002, Viala et al. 2005 and Brvar 2016) have paved the way for Diphoterine in the treatment of ocular chemical burns including CS gas. Whilst currently this solution may not be economically viable for many pre-hospital settings, it may well offer a safer and more efficacious alternative in the future.
Conclusion
Saline, water, dry air and L.A.W. are well established ocular treatments amongst HCWs or the general public. Recommending best practice is especially difficult faced with a lack of high quality evidence, conflicting studies, contradicting guidelines and the dissemination of inaccurate and confusing information via the internet.
Whilst further research will be necessary to enable recommendations for best practice, some important points should be remembered. The HCW should be aware that unless symptoms or medical conditions give cause for concern, medical intervention may not be necessary and the effects of CS gas will likely resolve spontaneously. If it is subsequently felt that the eyes must be irrigated, both saline and water are recognized treatments for irrigation. However, due to the ‘wash-in effect’ potentially prolonging the suffering of the casualty and the potential for contamination of the water source in a pre-hospital context, the use of saline would appear to be the wiser choice. When irrigating it must be ensured that supplies allow for copious and prolonged irrigation, otherwise the HCW may simply cause more pain. If using water, it should always be cold to minimize reactivation of the CS crystals. Blowing dry air into the patient's eyes should be thought of in the wider context of exposing the patient to ‘moving air’ and consider the most effective methods of doing so. Although the collective experiences of the general public on the front line should not be discarded, it is difficult to see the utility of L.A.W. for CS gas at this time based on current literature. Not only is evidence weak or non-existent but research looked at its effect on pepper spray and for mostly dermal pain. Efforts should thus be concentrated elsewhere. Diphotamine may be a safer and more efficacious alternative in the future pending economic viability for the treating HCW or organization.
Methods of decontamination will need to be adapted to local resources and the environment (WHO 2014b) but whatever the chosen method of treatment it should not be at the expense of the most basic, universally accepted and proven of actions. This essay highlights the need for the HCW to 1) prevent secondary effects by using appropriate personal protective equipment 2) extract the casualty from the area into a well-ventilated space 3) remove contaminated clothing and 4) offer reassurance. These are the most important of initial actions that should always be undertaken.