Effective pain control in post-operative patients is essential in ensuring patient's quick recovery, earlier mobilization and lower cost and higher patient satisfaction. The immune system of patients who have undergone surgery is suppressed owing to the surgery. The suppression is proportionate to the level of invasion by the surgery thereby, necessitating proportionate pain management measures. For effective post-operative pain management, consider the patient's physics, physiology, age and type of surgery (Vadivelu et al., 2010).
Tissue damage in surgical procedures is inevitable and results in pain to patients depending on their age, sex, and the degree of invasion by the surgery. Inadequacy of pain relief yields held up mobilization, further complications, anxiety and psychological distress. Chronic post-surgical pain is more common than realized, especially after certain types of surgery; for example thoracotomy and mastectomy. Uman et al. (2007) notes Predictive factors for developing continuing pain include preoperative pain, repeat surgery, prolonged surgery, severe postoperative pain, surgical approaches with a higher risk of nerve damage, chemotherapy or radiation, and some psychological and depressive symptoms. According to Uman et al. (2007) It is not clear how successful preventative measures such as pre-emptive analgesia may be in preventing chronic pain developing, but it is highly likely that early intervention when signs are detected is more likely to be beneficial.
Managing postoperative pain in the current healthcare environment can be difficult. Busy hospital wards, low staff numbers, limited time, inappropriate attitudes or focus on other imperatives, and inadequate knowledge all impede optimal postoperative pain management. This may be mitigated by producing an environment where pain management is considered a priority by introducing regular and accurate pain assessment, a multimodal treatment approach and a focus on responding to individual patient's needs. Many healthcare systems are under pressure to reduce patients' hospital stay and improve patient satisfaction. These aspects are compromised if pain management is not adequate.
Vondrackova et al. (2009) notes that, pain management regimens in post-operative patients should not be standardized. The nurse charged with the duty of care for post-operative patients need to understand the condition of the patients considering their psychological, medical and physical condition such as age; anxiety or level of fear; personal preference; surgical procedure; and response to agents given. This will guarantee effective pain management and quicken the patient's recovery. It is relevant to note the goal of managing of post-operative pain is to reduce medication doses, lessen side effects and, still provide adequate analgesia (Buvanendran et al., 2010).
Pain is predictable following surgery and gradually decreases over time (Buvanendran et al., 2010). Post-operative Pain (POP) is a highly individualized, complex, multi-dimensional experience that come about as a result of interactions between biological, psychological, environmental, and social factors (Australian and New Zealand College of Anaesthetists and Faculty of Pain Medicine (Mei W., 2010). If POP is not managed, effectively the patients' recovery can be adversely affected resulting in chronic post-surgical pain (CPSP) and even death (Mei W., 2010).
Nociception is the term used to describe the neural processes by which a noxious substance or a tissue damaging event such as surgical incision is perceived as pain. This is described in four stages, transduction, transmission, perception and modulation. Nociception involves a complex interaction between the central nervous system and peripheral nervous system including an evaluation of patients' pre and post-operative psychological and environmental influences. The tissue damaged caused by surgery results in the nociceptive system operating in a 'sensitized state of the patient. This encourages behaviors that guard the wound from further damage thus promoting wound healing (Samaraee, 2010).
Noxious stimuli associated with surgery are detected in the PNS by nociceptors of the sensory cutaneous and peripheral sensory afferents. These are distributed throughout the body in the skin, muscles, joints and viscera. They respond to a range of noxious stimuli that are associated with surgery. These are Mechanical stimuli, for example, surgical incision, pressure from swelling, inflammation, extravasation; Thermal stimuli, for example, heat from inflammation; Chemical stimuli, for example, chemicals released in response to tissue damage, inflammation, ischaemia, infection and wound cleansing agents (Samaraee, 2010).
The Physiology of Pain
Pain is not a single entity. It is variability reflects a rather the dynamic physiology of the nociceptive input from the periphery to the cerebral areas that interpret the nociceptive information. Pain is in general seen as either nociceptive, inflammatory or neuropathic, giving pain a patho-physiology correlate (McNicol et al., 2007). Nociceptive pain is the pain that results from activation of high thresholds peripheral sensory neurons (nociceptors) by intense mechanical, chemical or thermal noxious stimuli. Signals from these nociceptors travel primarily along small myelinated A-delta and unmyelated C. sensory afferent fibres to the dorsal horn of the spinal cord where they make synaptic contact with second order neurons. The signals travel post-synaptic to the thalamus and sensory cortex along the spinothalamic tract of the spinal cord (McNicol et al., 2007). This spino-cerebral signalling continues also partly to the hypothalamus and the limbic system, the loci being relevant in determining the individuals' emotional reactions to pain (Vondrackova et al., 2009). The nociceptive input and rostral transmission signalling are under the influence of both local and bulbo-spinal neural activity. These can bee either inhibiting or facilitating. There are numerous pharmacologically identified transmittors that can act as modulators in this circuitry of nociceptive input.
Inflammatory pain is the heightened pain occurring in response to tissue injury and inflammation. These results from release of sensitizing inflammatory mediators that leads to a reduction in the threshold of nociceptors that innervates the inflamed tissue (peripheral sensitisation). The peripheral sensitization is augmented by important biological processes that result in central sensitization of the spinal cord and rostral sites. As a result of an increase in the irritability of neurons in the central nervous system, inflammatory processes are also associated with exaggerated responses to normal sensory inputs. These phenomena, named allodynia or hyperalgesia that is evoked within a matter of minutes outlasts the precipitating tissue injury for hours or days. Spinal cord nociceptive neurons may become sensitized by repeated brief stimulation, which leads to prolonged spontaneous discharge i.e. The phenomenon of windup (Worwag & Chodak, 1998). This mechanism may hypothetically increase the level and duration of pain after surgery (Vondrackova et al., 2009) and legitimize thorough pain surveillance and analgesic medication.
Neuropathic pain is the pain that arises after injury to peripheral nerves or to sensory transmitting systems in the spinal cord and brain. As with inflammatory pain, allodynia and hyperalgesia typically reflects neuropathic pain.
In the period following surgery, inflammation, direct activation of nociceptors and in some cases injury to nerves, the clinical depiction is prevailed by self-generated breakthrough pain and resting referred to as the site of surgery; primary hyperalgesia, but also to the surrounding tissues; secondary hyperalgesia (B-y-kyilmaz, 2010).
Nociception is not synonymous with pain. This process may be ideal for the pain to prevail, but nociception is not enough to account for pain as a clinical presentation. Nociception is a physiological phenomenon, and pain is a perceptual involving higher central- nervous mechanisms. A nociceptive barrage may be perceived and reported as pain by one patient, but not necessarily by another. Such variability in individuals' perception of pain is common (Macrae, 2008). The neuromatrix theory of pain (B-y-kyilmaz, 2010) proposes that pain is not only a sensory event but rather a multidimensional phenomenon that could be influenced by past experience, cultural learning, and a host of cognitive and psychological variables. The brain possesses "the body-self neuromatrix." This integrates multiple inputs to bring about the output pattern that causes pain.
Post-Operative Pain Management Drugs
The increasingly popular approach controlling, managing and preventing post-operative pain is Mutimodal (balanced) analgesia. This involves the administration of a combination of non-opioid and opioid analgesics that act at different levels within the peripheral and central nervous system attempting to alleviate pain through control and healing. These measures seek also to reduce likely side effects such as sedation, vomiting pruritis, nausea and constipation (Vadivelu et al., 2010, Macrae, 2008).
Development and availability of newer agents to cater for post-operative pain management opens ground for possible combinations of multimodal analgesia. Therapy that is multi-pharmacological and based on synergistic effect of two or more drugs unveils desirable effects in reducing the recovery period compared to a monopharmacologic approach (Vadivelu et al., 2010).
Opioid analgesics play an relevant role in the treatment of pain in the immediate postoperative period. These drugs however, are associated with pre-operative complications such as sedation, drowsiness, Pruitus, ileus, constipation, ventilator depression and urinary retention. The effects of these opioids are adverse and substantially inhibit quick rehabilitation and recovery (Vadivelu et al., 2010, Buvanendran et al., 2010). Their effects are summarized to be sensory neurons hyperpolarization of first and second order, with inhibition…