Chapter 67 Michael T. Hilton and Paul M. Paris Pain and suffering are not confined within hospital boundaries. Pain is a common complaint of patients cared for by EMS providers. It is estimated that 20% of the approximately 15 million patients transported by EMS annually in the United States experience moderate-to-severe pain [1]. Although prehospital personnel are usually focused on the ABCs, the treatment of pain should be considered an important priority in the care of ill and injured patients [2,3]. Most studies of EMS analgesia practices show that many patients with moderate-to-severe pain do not receive analgesia in the prehospital phase of their care. NAEMSP currently recommends that EMS systems have a policy to address prehospital pain management [3]. The initial statement in NAEMSP position paper is, “NAEMSP believes that the relief of pain and suffering of our patients must be a priority for every EMS system. Adequate analgesia is an important step for achieving this goal. NAEMSP believes that every EMS system should have a clinical care protocol to address prehospital pain management. Adequate training and education of prehospital personnel and EMS physicians should support the pain management protocol.” Prehospital pain protocols should address the following issues. The challenge of treating pain in the prehospital setting is to use agents and techniques that are not only effective but safe and do not lead to physiological compromise or a delay in diagnosis upon arrival in the ED [5,6]. Because of inordinate fears of “masking the diagnosis” and the desire to prevent side-effects, many EMS systems have opted for little or no use of pharmacological analgesics. Providing analgesia has been largely ignored in prehospital care education [1]. Few EMS texts devote significant attention to this topic. Many systems do not have protocols to treat pain and suffering, other than that from ischemic chest pain [7]. Many prehospital providers are frustrated by being unable to offer patients more than the “bite the bullet” approach to providing relief from acute pain. For those systems with reasonable analgesia protocols, the majority of patients are still untreated or undertreated. Many paramedic attitudes have been suggested as reasons for this inadequate treatment of pain [8]. Prehospital pain management is a fertile area for study. Current research topics include barriers to prehospital analgesia, interventions to address barriers, non-opioid alternative analgesics (e.g. ketamine, IV acetaminophen), and alternative routes for pain relief, such as intranasal and transmucosal routes that can be used by basic providers as well as field-based ultrasound-guided nerve blocks that can be useful in wilderness settings or in prolonged extrications [9]. Several studies have shown that oligoanalgesia is more the rule than the exception in prehospital care. One of the most dramatic studies was performed by White et al. in the city of Akron in the late 1990s [10]. At that time, the EMS system had standing orders for either the administration of morphine sulfate, 2–5 mg IV push, or nitrous oxide, 50% self-administered. During the study period, 1,073 patients with suspected extremity fractures were identified. Of this large number of patients, only 18 received analgesia: 16 patients received nitrous oxide and two received morphine. McEachin reported on several different EMS agencies transporting patients to a single hospital in Michigan [11]. Of 124 patients suspected of having lower extremity fractures, only 22 (18.3%) received parenteral analgesia. Many of these patients (38.4%) were triaged from an ALS response to a BLS transport. Hennes et al. reported results from prehospital analgesia practice in Milwaukee where a review of 5,383 patients with acute pain showed that morphine was administered in only 258 patients (4.8%) [12]. Of those patients with extremity fractures, 37 of 351 (10.5%) received morphine, and morphine was given to only seven of 258 children (3.0%). In patients with burn injury, 16 of 130 (12.3%) received morphine; only one of 12 children received it. Similar findings showing lack of analgesic administration or oligoanalgesia have been replicated in other studies [13,14]. The benefits of prehospital analgesia are not only physiological. It improves the perception of quality of care provided by EMS. One study showed that 80% of patients reported the overall quality of EMS care to be excellent when they rated their pain management as excellent. Prehospital analgesia also dramatically decreases the time-to-analgesic administration, ranging from 60 to 120 minutes earlier, when compared to analgesic administration being deferred to the emergency department [15–17]. Evans made the poignant statement, “To allow a patient to suffer unnecessary pain does harm to the patient – a violation of the first ethical principle of medicine” [18]. In a 1999 editorial, the late Peter Baskett states, “The blame for ‘oligoanalgesia’ must be laid at the door of physicians in authority who have, through ignorance, underplayed the physiologic and psychological benefits of analgesia and overplayed the potential of deleterious side effects of agents that are commonly available” [19]. Opioids are the best class of pharmacological agents to treat acute pain in all areas of medicine, including the prehospital environment. (See Box 67.1 for a list of desirable characteristics, most but not all of which are found in the opioids.) Osler referred to opioids as “God’s own medicine” [20]. The properties that make opioids desirable in the field include rapid onset, high potency, titrateability, relative safety, and reversibility. Morphine sulfate has been used for ischemic chest pain in the field for the past three decades. Over the past several years, fentanyl has gained increased usage. In many EMS systems, it is now the most commonly used opioid for non-cardiac pain. In emergency departments and in the field, it is increasingly replacing morphine for myocardial ischemia and chest pain. For many types of pain, opioids can be titrated by the IV route to produce safe and effective analgesia and can be administered by the intramuscular and intranasal routes as well [21,22]. One of the major benefits of opioids is that most side-effects can be rapidly reversed with an opioid antagonist, such as naloxone, which is carried by most EMS systems for use in opioid overdoses. With all opioids, EMS systems must adhere to Food and Drug Administration guidelines for monitoring and documenting possession and use. Specialized critical care transport teams seem to provide analgesia and achieve significant pain relief more frequently than described in routine ground-based EMS systems [23]. Fentanyl has several properties that make it well suited for prehospital use. It is one of the only opioids that does not cause a release of histamine, thereby preventing potential exacerbation of reactive airway disease, and reducing the chance of inducing significant hemodynamic changes. Fentanyl is very lipid soluble, and it crosses the blood–brain barrier quickly, reaching its peak effect within a few minutes. Its half-life is shorter than most other opioids with a duration of action less than 1 hour. Fentanyl does not cause any decrease in cardiac contractility. Like all opioids, however, it can decrease sympathetic tone and if a patient’s blood pressure is dependent on the sympathetic nervous system, fentanyl can cause some hypotension, but this is relatively uncommon. Kanowitz reported on the use of fentanyl in 2,129 prehospital patients with an average titrated dose of 118 μg, with a range of 5 to 400 μg [24]. Only 12 patients had any vital sign abnormalities during the drug’s duration of action, and most of these were relatively minor, with only one patient receiving naloxone reversal. This one patient was an 83-year-old woman with a hip fracture who received two doses of 100 μg fentanyl and had some respiratory depression while in the ED that was immediately reversed with 0.4 mg of naloxone without any adverse effects. There were no significant complications or deaths as a result of prehospital use of fentanyl. The authors concluded that fentanyl effectively decreased pain scores without causing significant vital sign changes, thereby allowing it to be used safely and effectively for prehospital pain management. Several studies have also been reported showing the safe and effective use of fentanyl in ground and air transport of adult and pediatric patients [25,26]. Fentanyl has a short half-life and duration of action of 60 minutes or less. Opioid-induced hypotension is rare with fentanyl, but in patients who are only able to maintain normal systemic pressure due to extreme sympathetic drive, fentanyl can blunt the sympathetic response and theoretically lower blood pressure. Should this occur, fluid administration is typically all that is needed, but alpha-adrenergic agents can be used to help to restore blood pressure. The safe and effective use of oral transmucosal use of fentanyl has been described in the battlefield setting [27]. Fentanyl also has been used via the intranasal route through an atomizer device [28]. In some systems, fentanyl is replacing morphine as the opioid of choice for ischemic cardiac chest pain. Morphine has been widely used in EMS systems for the past three decades. Initially it was largely restricted to the treatment of ischemic cardiac pain, but its indications have expanded to a wide variety of pain states. Despite the potential for a multitude of side-effects related to the prehospital use of morphine, the literature does not suggest that these have been a major clinical issue. Morphine has the advantage of having a wide margin of safety when it is used in careful IV titrated fashion [29]. It is safe in patients with liver disease and for acute pain and can be used safely in renal disease. Morphine does not decrease cardiac contractility but does decrease preload and afterload and therefore should be used with caution in any patient who has borderline or frank hemodynamic instability. It is important to titrate the dose to the analgesia accomplished. Some characteristics of the opioid agonist-antagonist class of analgesics make them ideally suited for prehospital use. Drugs in this group include nalbuphine and butorphanol. The primary benefits of this class are the ceiling on respiratory depression, minimal euphoria and limited abuse potential, lack of biliary spasm, and minimal hemodynamic effects. Stene et al. described the prehospital use of nalbuphine in 46 patients with moderate-to-severe pain due to multiple trauma, burns, fractures, and intraabdominal conditions [30]. The agent was partially to completely effective in 89% of patients and was without any major untoward effects. Nalbuphine also causes very minimal, if any, hemodynamic changes. Since that early study, others have confirmed the value of IV nalbuphine in the field [31,32]. Another advantage of this drug is that it is not a controlled substance, easing some of the paperwork required when using morphine. Butorphanol is now available as a nasal spray [33,34]. This agent and route of administration have many theoretical benefits in the prehospital environment, but studies have yet to be reported on the field use of nasal butorphanol. The use of the agonist-antagonist class of analgesics in the field may result in patients in the ED requiring somewhat higher doses of pure opiate agonists to achieve adequate analgesia [35]. Nitrous oxide-oxygen mixtures fulfill many of the properties desired for a prehospital analgesic [36–38]. Several field studies have demonstrated the safety and efficacy of self-administered 50% nitrous oxide in prehospital care [39–41]. All studies have confirmed that the majority of patients with moderate-to-severe pain from a variety of sources will achieve significant pain relief. In unpublished data from use in the city of Pittsburgh in the past two decades, over 4,000 patients have been treated without any significant major adverse effects. Significant analgesia is achieved in approximately 80% of patients. In a rural EMS system, a nitrous oxide-oxygen mixture led to pain relief in 85% of patients for which it was used [42]. One of the major advantages of the use of nitrous oxide is that it is relatively devoid of serious side-effects. Its major side-effect has been nausea, noted in four patients in a study by Ducasse et al., which also found that numerical rating scores decreased significantly with use of a nitrous oxide-oxygen mixture [43]. In 1994, an alert entitled “Controlling exposure of nitrous oxide during anesthetic administration” provided guidelines to prevent environmental levels from exceeding their recommended standards. In a moving vehicle, or one with a fan, short-term administration should be safe for the providers, although well-designed protocols must be written and followed when using this gas mixture. A prototype of a nitrous oxide protocol is shown in Box 67.2; it includes the absolute and relative contraindications to nitrous oxide administration [44].
Analgesia
Introduction
Literature review
Opioids
Fentanyl
Morphine
Opioid agonist-antagonists
Nitrous oxide
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