Pain management and oligoanalgesia in emergency departments

Pain Management in the Emergency Department

Pain is a complex neurobiological problem that involves the nervous system, cognitive system as well as the emotional system. The highly subjective nature of pain makes its assessment and management a complex problem. Oligoanalgesia or under treatment of pain is widely observed in the ED. Multimodal or combinational therapy is found to be the most effective in providing relief from acute pain. Formulating and implementing a framework for pain management in all emergency departments would definitely reduce patient suffering time and improve pain management outcome.

Pain is the most common problem in any emergency setting. Cordell et.al reports that almost 70% of patients arriving at the ED complain of pain. [1] Pain management is one of the important yet undertreated issues in the emergency department of any hospital. Oligoanalgesia is found to be a common problem with hospitals both in the rural and urban settings highlighting the need for more effective pain management strategies. It is not such an easy task for emergency room physicians to handle pain management for the entire spectrum of patients ranging from neonates, children, adults and the elderly. Typically, young children and the elderly are less likely to receive analgesia even in case of severe fracture for fear of undesirable complications. More than a decade ago, the Canadian association of emergency workers concluded from their extensive review of literature that healthcare workers tend to "underestimate patient suffering." [2] Several studies since then have also reported poor assessment of pain and Oligoanalgesia as common in the ED in any hospital. It is also a known issue that some patients abuse pain care in the hospital setting by using the ED as the gateway to drugs. This makes the physician's job much more complex and may also affect diagnosis and appropriate intervention. A brief overview of pain, its pathology, psychology and the different treatment interventions would help us better understand the issues surrounding pain management in the emergency department.

Pathology of pain

The pathology of pain includes both neurological as well as biochemical processes. The perception of pain also involves many factors like environmental, social and cultural influences. Pain is mainly classified into two types namely acute pain and chronic pain. Acute pain is caused by an underlying pathological condition or an injury and is usually relieved soon. The PPSG defines acute pain as "Acute pain -- normal predicted physiologic response to adverse stimuli associated with surgery, injury, or illness. Typically it is time limited and responds to opioids and other treatment modalities" [3]

The main mediating agents for acute pain are nociceptors, the free nerve endings of specialized nerves. The nociceptors are triggered in response to chemicals such as leukotrienes, thromboxanes, bradykinins, serotonin and histamine that are released after a tissue injury. These nociceptors trigger an afferent nerve impulse that propagates along the peripheral nerves, gets processed in the dorsal horn and then ascends through the spinal column into the brain. Different centers in the brain are involved in the interpretation of the signal and a response signal travels from the brain along the spinal column into the peripheral nerves. [4]

Pain can also be classified based on the anatomy of its origin into three main types namely somatic, visceral and neuropathic. Different types of somatic nociceptors produce different kinds of pain such as burning sensation, pirking, etc. The three main types of somatic nociceptors include A? mechanical nociceptors, A? mechanoheat nociceptors and C. polymodal nociceptors. The A? mechanical nociceptors originate from myelinated axons and conduct signals at the rate of 4 to 44 m/sec. The C. polymodal nociceptors are from unmyelinated axons and conduct signals at the rate of 0.5 to 1 m/sec. [5]Visceral pain is pain due to injury sustained by the internal organs of the body or due to conditions such as ischemia, fibromyalgia, spasms, muscle distention, etc. Since some of the visceral afferents make use of autonomic pathways to access the central nervous system, autonomic symptoms such as vomiting, nausea, sweating, bradycardia etc. are often associated with visceral pain. Finally, neuropathic pain is the pain caused due to disturbance in the central nervous system or due to injuries to the peripheral nerves. The pain is typically felt far away from the site of damage as in the case of spinal disc prolapse, which causes shooting pain in the legs. [4]

Psychology of Pain

Understanding the psychology of pain is as important as understanding its pathophysiology. The limbic system that includes the hippocampus, amygdala, limbic cortex etc. is the seat of emotional and behavioral processing. Studies have shown that performing frontal lobectomy considerably relives the affective component of pain in patients with cancer and seizure. The perception of pain is affected by a variety of factors such as context, attention, anxiety, memory, expectations and belief. A case pertaining to the contextual perception of pain is that of soldiers at the warfront who sustain severe injuries and report only mild pain. The emotional reaction to pain is found to be affected by the attention to it. Studies have shown that distracting the mind results in reduced experience of the pain. Anxiety or the fear of pain or the nervousness about being unable to control the situation leads to increased suffering. Distracting the patient by discussing things that interest him can be a useful approach to minimize the discomfort during invasive interventions. Research has also shown that in some cases pain can be a conditioned response to particular stimuli. Also the perception of pain can be altered by exposure to different levels of tolerance to pain. [6]

The psychology of pain plays a big role in chronic patients. Thus improving the subjective feeling of pain is most beneficial for speeding up the recovery process of patients suffering from chronically painful conditions. Addressing the psychiatric causes of pain is as important as assessing and treating the symptom itself. This would avoid a vicious cycle of pain related depression and depression induced greater perception of pain that most chronic patients suffer from. Also some patients tend to develop a 'drug seeking behavior'. Prolonged usage of opioids for example leads to an addictive personality. This puts physicians under a predicament particularly when they strongly suspect a 'drug seeking behavior' while faced with the obligation to provide treatment.

Chronic Pain in the ED

Several studies such as Nielson et.al, Eliot et.al have concluded that chronic pain is a rather common problem with patients presenting in the emergency department. A recent study by Cordell et.al (2002) also showed that almost 52% of 1665 people who visited the ED complained of pain and of these 38% of the patients were clearly identified with chronic pain syndrome. [7]This highlights the importance of chronic pain care in the ED. Since physiogical, psychological and social factors are involved in chronic pain it is not possible for the physician in the ED to assess all these factors into consideration given the lack of time for such a comprehensive evaluation. The complex pathophysiology of chronic pain makes it all the more difficult to manage in the ED. For example, opiate medications which are generally used and found to be very effective for acute pain would not be as effective in chronic pain patients as they tend to develop receptor mediated tolerance (N- methyl-D-Asparate). Furthermore, as opiates are strongly addictive, patients tend to persist with them inspite of the paradoxical opiate induced pain due to descending pain facilitation. [8]

Training for Acute Pain Management

As we discussed above, pain management falls short of optimum care in most of the ED settings in any hospital. Pain being a subjective feeling is difficult to assess correctly and interventions in most cases fail to relive the patient completely. Oligoanalgesia or under treatment of pain is a widely observed. Selbst et.al (1990) reported that even patients with long bone fractures were under treated and received only mild anesthesia. Ngai etal (1997) documented the use of analgesics both in the ED and post discharge. [9] This study also confirmed under treatment of pain. Fosnocht et.al (2001), Lewis et.al (1994) and two other studies have also reported that only 30 to 63% of patients in the emergency department receive analgesics. In general there is a stingy attitude on the part of the ED physicians when it comes to administering analgesics. It is observed that even with the plethora of research on pain and its under treatment in the ED there is not much done in the form of developing and implementing a framework of pain management in the ED. Though implementation of guidelines has been reported to be successful and shown to improve patient satisfaction, one of the main concerns is the resistance by doctors as it exposes them to legal action in case of failure to adhere to the standard procedural evaluation and intervention.

One of the recent studies conducted on the effectiveness of pain management training for healthcare professionals in the ED turned out to be a promising one. This cohort study by Isabelle et.al observed 249 and 162 patients in the pre and post intervention periods respectively. The study observed that post training pain documented by physicians and nurses increased from 61% and 76% to 78% and 85% respectively. Also noticeable was the increase in dosage of analgesia from 40% to 63% and of morphine from 10% to 17% while intravenous morphine dosage increased from 2.45 to 4.6 mg. The visual analogue scale score, which is an indicator of pain, also showed a marked reduction from 2. 9 cm to 2.1 cm post training suggesting a significant improvement in pain management and patient satisfaction.[10] This cohort study clearly showed that pain management in the ED can be considerably improved by providing appropriate training for the ED staff and by implementing pain management guidelines for the ED.

Treatment Modality

Pain is a complex neurobiological problem that involves the nervous system, cognitive system as well as the emotional system. No single pharmaceutical agent can provide total relief given the multiple mediators, receptors and processes involved in the experience of pain. Effective intervention would most likely be a combinational therapy that uses the varied mechanisms of action of different drugs. Most ED physicians find multimodal therapy to be optimal for pain care. Multimodal therapy involves the use of two or more methods of pain control. For example, anti-inflammatory drugs are combined with sedatives and anti-convulsants, opiods, etc. This combinational therapy also helps to minimize the side effects and to reduce the dosage of component analgesics. Acetaminophen is a widely used synthetic analgesic with anti-pyretic properties. This is widely prescribed for musculoskeletal injuries, headaches, back pain, earache, etc.,. Acetaminophen is regarded as the safest drug for children and elders as it is well tolerated. Nonsteroidal antiinflammatories [NSAIDS] are another class of drugs widely used in the ED for pain relief. Drugs of this class work by inhibiting cyclooxygenase, the enzyme responsible for prostaglandin biosynthesis. NSAIDS have anti-inflammatory, analgesic and antipyretic properties. One serious side effect of using NSAIDS is the injury to the GI tract (possible peptic ulcer) due to the inhibition of prostaglandin. [13]

Conclusion

Given the highly subjective nature of pain, its assessment and management present a complex problem. Often in the ED much time and effort is devoted into the diagnosis of the underlying cause of pain rather than in relieving pain. A close review of the numerous pain management literature involving ED suggests that treatment and diagnosis do not proceed simultaneously in the ED and that diagnosis always precedes administration of analgesics. Optimal pain care in the ED therefore calls for a considerable change in our approach to handling a pain scenario. Relieving the patient's distress should be a high priority. To quote Albert Schweitzer, "We must all die. But that I can save a person from days of torture, that is what I feel is my great and ever-new privilege. Pain is a more terrible lord of mankind than even death itself." [12] Analgesia should be given a high priority in the ED setting. Psuedo addiction is often misinterpreted as 'Substance addiction and abuse' leading to under treatment of chronic pain. There is enough research evidence to suggest that a framework for pain management be formulated and implemented in all hospital emergency departments. This would definitely reduce patient waiting time and improve pain management outcome.