Illicit substance and drug intoxications may progress into life-threatening conditions which require immediate medical attention. In the adult population, ethanol-, opioid-, and benzodiazepine-related intoxications are common among hospitalized patients.1,2 The most severe symptoms of illicit substance intoxications are respiratory depression leading to respiratory arrest and cardiac-related problems such as tachycardia and cardiac arrest.3–6 Especially, opioid use in the context of prehospital poisoning is associated with high mortality.7
Illicit substance and drug intoxications in the prehospital setting are problematic because the actual substance may be difficult to identify or the intoxication is a result of multiple substance abuse and alcohol. In addition, the patients themselves can be unaware of the substance used. Intoxicated patients may be disoriented or unconscious, which may render the availability of anamnestic information impossible. In some cases of substance abuse, such as opioid- and benzodiazepine-related, treatment with an antagonist may reverse the effects of an overdose, improve the patient's clinical condition, and prevent unnecessary and potentially harmful treatment procedures such as airway management and further intensive care.3,8,9
Oral fluid screening for illicit substances has been used for forensic testing by police in the prehospital setting, but, to our knowledge, there are no previous studies regarding the use of this method in the context of emergency medical service (EMS).10,11 The aim of this pilot descriptive study was to evaluate whether on-site OF screening improves the diagnosis and treatment of EMS patients presenting with either a lowered level of consciousness due to an unknown cause or in association with known substance abuse.
MATERIALS AND METHODS
As a pilot sample, all consecutive patients in whom an OF screening test was performed by the physician-staffed mobile intensive care unit (MICU) of Pirkanmaa, Finland, between January 1, 2012 and May 31, 2013 were retrospectively analyzed. The MICU was staffed by an anesthesiologist and a paramedic, served a population of circa 500,000, and responded to high-risk medical and trauma-related emergencies such as cardiac arrest and high energy trauma. The study was based on EMS run sheets and hospital medical records and approved by the institutional review board of the Pirkanmaa health district (R14147, November 4, 2014). As the study was a retrospective chart review of nature, the need for patient consent was waived.
In the MICU, OF screening test (Drugwipe 6s, Securetec Detektions-Systeme AG, Germany) is used in cases of severe intoxication, in which a diagnosis of specific substance use may modify treatment. The OF screening test may also be used in cases when the patient presents with a lowered level of consciousness and no readily treatable or specific cause can be identified.
The test qualitatively analyzes the presence of amphetamine, methamphetamine, benzodiazepines, cocaine, opioids, and cannabis from OFs or sweat, based on antigen-antibody reactions. The performance characteristics of the test have been previously reported elsewhere.10,11
For data collection, patient characteristics, the cause of EMS activation, and OF screening test results were recorded. Prehospital care was evaluated in regard to the OF screening test result, that is, whether the test result modified patient care and whether there was any clinical impact observed.
During the study period, the MICU attended 119 patients with a suspected lowered level of consciousness due to an unknown cause or intoxication. A total of 57 patients were tested with the OF screening test owing to uncertainty of the actual cause of unconsciousness or the nature of intoxicating substances. Of the 57 patients, in 8 cases, OF screening test results were not recorded and thus excluded from the final analysis. Of the final 49 patients, 35 (71%) were men and 14 (29%) were women and their median age was 34 years. Sixteen patients (33%) tested positive for one or more of the substances identifiable by the test. The distribution of these substances is described in Table 1. None of these patients tested positive for cocaine.
In 6 (38%) of the 16 patients, treatment was modified based on the results of the OF screening, and in 4 of these cases, a clinically relevant response could be observed in the prehospital phase. The characteristics of these four patients are described in Table 2. In the remaining 2 patients, the effects of benzodiazepine poisoning were reversed with flumazenil in the early phase of emergency department treatment.
Based on these data, OF screening for intoxicated or unconscious EMS patients affected differential diagnosis, as 16 patients tested positive with the OF screening test. Of these 16 patients, directed medical treatment based on the results of the OF screening test could be provided in 6 patients. The 4 patients who had a positive outcome with the modified treatment avoided intubation prehospitally and therefore immediate intensive care in the hospital. This suggests that OF screening does have diagnostic value in the prehospital setting and can result in improved treatment for patients.
Illicit substance intoxication diagnosis commonly relies on typical symptoms of intoxication. Also, external clues of illicit substance use and information provided by the patient or bystanders are valuable when confirming the diagnosis of intoxication.12 All of these external signs may not be available or accurate, or information cannot be acquired owing to the patient's lowered level of consciousness. In these scenarios, OF screening may provide further diagnostic information and thus modify the provided treatment.
The present cost to test 50 patients with the OF test is approximately 1100 euros, which is well below the average daily cost exerted by the intensive care of an intubated patient.13 Based on the 4 patients in whom prehospital intubation and intensive care were avoided in this material, the use of the OF screening test could be characterized to be of good cost-benefit in selected patients.
This study carries limitations owing to the retrospective study setting; in 8 cases, the screening test results were missing and thus excluded. Although superior in terms of feasibility in the prehospital setting, the OF screening test is limited in sensitivity and specificity, as reflected by the comparison with urine screening test results. In addition, the cut-off values for the illicit substances in Drugwipe 6s are same or close to the cut-off values determined for detecting driving under the influence of drugs, and therefore, a positive result does not always indicate intoxicating levels of the substance.11,14,15
Furthermore, studies on the performance capabilities of Drugwipe have shown that detection of amphetamines is reliable, but the sensitivity for cocaine, opiates, and cannabinoids are not entirely satisfactory. The sensitivity and specificity values have also varied from study to study. There are no studies on the sensitivity and specificity of Drugwipe 6s for benzodiazepines, as the previous studies have been carried on older versions of Drugwipe, which do not have this feature.11
Illicit substances and their metabolite concentrations in OF and blood do correlate, but there is individual variation in OF to blood concentration ratios.16 As blood and OF concentrations are directly proportional, one could expect that the sensitivity of OF screening would improve when testing people who are suspected for overdosing.
Finally, from a clinical viewpoint, it cannot be evaluated whether the treatment and clinical course in the individual patient were affected solely by the screening test results, that is, empiric treatment with an antidote might have been attempted even in the absence of a positive screening test result for an intoxicating substance. However, in the case of the 4 patients with modified treatment and favorable prehospital response, no clear signs or information suggesting the use of a substance treatable with an antidote was available in the prehospital phase.
In conclusion, OF screening for illicit substances can be a valuable diagnostic tool in addition to the usual diagnostic methods in EMS patients with unconsciousness due to an unknown cause or signs of intoxication. The results of OF screening should be only used as a part of the differential diagnosis, and no definite conclusions should be drawn purely on the test results, that is, the results should be used on a “rule in” rather than a “rule out” basis. In selected cases, invasive and potentially harmful procedures may be avoided when treatment is modified by the OF screening test, for example, via reversal of the effects of intoxication using antagonist treatment.
This work is dedicated to Dr Janne Virta (1969–2016).
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