Johnston is a healthy and fit 27 year old male who just had a left pneumonectomy following the diagnosis of primary lung adenocarcinoma. His vital signs upon admission to the ward are within normal range; only his breathing rate is 12, which is bordering bradypnea. He has an indwelling catheter insitu, and his IV line is delivering Normal Saline 18/24. For pain relief he has 0.125% Marcain delivered through epidural infusion at 5mL/hr. This essay will discuss the postoperative care of Mr.Johnston in response to questions, with a focus on acute pain relief through epidural analgesia.

             Question 1.

             The IASP defines pain is "an unpleasant sensory or emotional experience associated with actual or potential tissue damage, or described in terms of such damage" (American Pain Society, 2008). This definition acknowledges that pain is a perception and not a sensation; and that the experience of pain is subjective and is influenced by thoughts, feelings and behaviour (Macintyre, NHMRC & ANZCA, 2010). Pain has been poorly treated in the past due to many preconceived ideas and myths such as "Pain is not harmful ", and "High doses of narcotics can easily cause addiction(Willis, 2007). Although the deleterious effects of unrelieved pain is well known today, postoperative pain is still undermanaged in the hospital setting (Apfelbaum, Chen, Mehta & Gan, 2003).

             Postoperative pain is a form of acute pain as it occurs due to injury such as surgical incision (Macintyre, NHMRC & ANZCA, 2010). Acute pain is one of the activators of the systematic stress response in the body, which includes complex neurohumoral and immune responses (Macintyre, NHMRC & ANZCA, 2010). The systematic stress response is activated when the nociceptors (C and A-delta fibres of primary afferent neurones that are in the periphery and viscera) detect a tissue damaging stimuli (Hall & Guyton, 2011). Upon activation, chemicals such as hydrogen ions, substance P, adenosine triphosphate, serotonin, histamine, bradykinin, interleukins and prostaglandins are released systematically and into the damaged tissues (Hall & Guyton, 2011).