The Physiological basis of Pain and other Common Symptoms Associated with End of Life

Introduction

The actual dying process normally starts well before an individual’s physical death. While the date and time of an individual’s death are unpredictable, death, however, and whenever it occurs, is normally preceded by a number of physiological and psychological changes. Dying individuals and the elderly often tend to die after a period of deterioration that is caused by one or more chronic progressive illnesses. The suffering that typically tends to characterize the period before death can in part be related to the dying individuals experiencing unrelieved symptoms with pain being the most prevalent of these symptoms. This paper will seek to provide a description of the physiological basis of pain and other common symptoms that are normally associated with the end of life processes.

The chronically ill and the elderly have the highest prevalence of disability, comorbidity, and frailty of any demographic. A study conducted by Smith et al., (2010) found that there is a relatively high prevalence of pain during the end of life processes with 25% of all study respondents being reported to have experienced pain during the last two years of their lives. This percentage doubles to 50% during the last four months of an individual’s life. Pain is commonly associated with many end stage diseases and a key component of pain management for the elderly and the terminally ill individuals is to determine the physiology of the pain that is being experienced so as to allow for the palliative care team to developed an individualized pain management plan. There are three types of pain that individuals can experience during the end of life processes, these are a somatic pain, visceral pain, and neuropathic pain.

During the end of life processes, chemical, thermal or mechanical nociceptive stimulation can recruit peripheral nociceptors that serve to conduct nociceptive signal originating from the somatosensory neuron to the spinal cord’s dorsal horn. The primary neuron situated in the dorsal horn works to establish a synaptic contact with the secondary neuron. Secondary neurons form the lateral and medial tracts promptly cross in the spinal cord so as to send afferent projections to the higher centers. A second synapse in the medial and lateral nuclei of the thalamus will be caused by the presence of a relatively high proportion of afferents. The second synapse will in-turn make synaptic contact with tertiary neurons. These tertiary neurons send afferent to the secondary and primary somatosensory cortices that serve to determine the sensory quality of pain such as its intensity, location, and duration. The tertiary neurons are also noted to project to the limbic structures such as the insula and the anterior cingulate cortex which are involved in the emotional or affective component of pain (Marchand, 2008).

Another common symptom that is associated with the end of life processes is that dying individuals at times tend to lose interest in drink and food. This is because their ability to swallow drinks and food becomes severely impaired as a result of their suffering from dysphagia (Buning & Bullock, 2016). Dysphagia is defined as difficulty in swallowing liquids and solid foods and is normally an indicator that an individual is suffering from some other disease. The act of swallowing liquids and foods entails the use of over 50 different muscle groups; unimpaired nerve conduction and the presence of an intact oropharyngeal anatomy that will serve to allow for there to be smooth coordination between the digestive system and the respiratory system. From the start of the swallowing process to the end of this process, a single swallow is observed to take about 20 seconds and occurs in four distinct stages.

The first stage of swallowing is the oral preparation stage where the tongue and teeth work to break down the food that is to be ingested into small pieces. As the food is broken down in the mouth, it is mixed with saliva and the tongue works to form this food into one or two small boluses. The second stage of the swallowing process is the oral transit stage where the lips are drawn to a close so as to seal the food boluses within the mouth. The tongue then propels these boluses towards the pharynx in preparation for the next stage of swallowing. The pharyngeal stage of swallowing involves the tongue’s involuntary posterior movement. The passage of the food boluses through the pharyngeal acts as a stimulus that stimulates nerve bundles that send a signal to the medulla oblongata swallowing center. Upon the receipt of this signal, the medulla oblongata triggers a peristaltic wave that works to push the bolus into the esophagus. The final stage of the swallowing process is the esophageal stage and this stage involves food movement through the peristaltic process first through the upper and then through the lower esophageal areas and into the stomach (Affoo et al., 2013).

Any disruptions that at any stage of the process can greatly interfere with swallowing. These disruptions can include brain damage from strokes; the patient suffering from diseases such as dementia, Parkinson’s disease, and amyotrophic lateral sclerosis that work to affect the body’s neurological system; conditions causing reflux; internal obstructions in the digestive system caused by cancerous growths and lesions; as well  as the general deconditioning that occurs in the body and is normally associated with end of life processes and the end stages of terminal or chronic illnesses (Affoo et al., 2013).

Another common symptom that is often presented by individuals during the end of life processes is the production of terminal secretions that cause the dying individual to produce a noise that is often referred to as the death rattle when breathing (Lokker et al., 2014). This noise is produced by the oscillatory movement of secretions that occur in the trachea, the hypopharynx, and the oropharynx during expiration and inspiration in unconscious terminally ill patients. The origin of this secretions is the bronchial mucosa and the salivary glands.

The reported incidents of death rattle during the end of life processes of terminally ill patients vary strongly from about 6% to 92% of these patients. Most of the studies that have been conducted to examine the incidents of death rattle during the end of life processes have been conducted by observing patients dying from cancer with the majority of these patients having been admitted to hospices and palliative care units. Death rattles are most commonly reported as occurring in patients that are dying of brain metastases, pulmonary malignancies, or primary brain tumors. In about 75% of the patients that produce death rattles, Mercadamte et al., (2014) notes that these rattles predict death within 48 hours of their occurrence. Some medical authors argue that it is important to distinguish rattles caused by respiratory pathology (pseudo-death rattle) and rattles produced by bronchial secretions and non-expectorated salivary secretions (the real death rattle). The real death rattle often tends to respond well to the administration of antimuscarinic drugs that provide anticholinergic therapy while the pseudo-death rattle does not respond well to the administration of these medications.

Another common symptom that often presents during the end of life processes is skin failure. Skin failure is broadly described as an event where the skin and the underlying tissues happen to die as a result of increased hypoperfusion. Skin failure is observed to occur at the same time as the failure or dysfunction of other organ systems in the body of an individual undergoing end of life processes. During skin failure, hypoperfusion causes the skin cells to start to die and this causes the skin to be unable to perform its role in maintaining the body’s water balance, temperature as well as its vasomotor tone (Levine, 2016). In addition to this, dying skin is also unable to protect the body from mechanical trauma and infection. Skin failure can manifest as subjective symptoms such as localized pain or as objective changes affecting skin integrity, turgor or color. End of life processes can affect the body’s homeostatic mechanisms and this causes the body to react by shutting blood flow from the skin and channeling it to its vital organs. This in-turn has the effect of triggering a reduction in the normal cutaneous metabolic processes as well as soft tissue and skin perfusion. Minor insults in cases with skin failure can result in major complications such as pressure ulcers, gangrene, skin tears, skin hemorrhage as well as infection.

Conclusion

The actual dying process normally starts well before an individual’s physical death. Individuals with chronic terminal diseases and the elderly often tend to die after a period of deterioration. The suffering that typically tends to characterize the period before death can in part be related to the dying individuals experiencing unrelieved symptoms with pain being the most prevalent of these symptoms. There are three types of pain that individuals can experience during the end of life processes, these are a somatic pain, visceral pain, and neuropathic pain. As the end of life processes advances, it is also common for dying individuals to lose and interest in drink and food as they ability to swallow food becomes severely impaired as a result of their suffering from dysphagia. Other common symptoms that are usually associated with the end of life processes include skin failure and terminal secretions that trigger the death rattle. The death rattle is normally predictive of death occurring within 48 hours of its occurrence.

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