Introduction
Adenocarcinoma is a subtype of lung cancer. It is under the major classification of non-small cell carcinomas. They mainly affect women and men who do not smoke (Kumar, Cotran, & Robbins, 2007, pp. 678). Adenocarcinomas progress gradually, but they metastasize at early stages (Goljan, 2007, pp 67). This, therefore, means that they have to be dealt with earlier because cancer is difficult and more expensive to manage after there are foci of metastasis.
The carcinomas of the lung also need early treatment because once they progress, they have a poor prognosis (Jakab, 2006, pp.89). Factors that indicate that the cancer is still localized and resectable are; expectoration and chronic cough, alternatively, signs of late-stage disease are; chest pain, hoarseness of the voice, pleural or pericardial effusion, superior vena cava syndrome, and recurrent segmental atelectasis (Young et al. 2011, pp.168). The common sites for metastasis are the brain, liver, and bone. The treatment of choice in early-stage cancer is resection (Alter, 2009, pp. 18).
The reason why doctors prefer epidural analgesia instead of other forms of analgesia is the fact that it provides exceptional pain relief postoperatively. It also reduces the use of opioids, for that reason, avoiding the side effects of opiates especially dependence (Jarrell & Carabassi, 2008, pp 57). It can also be used for extensive periods, thereby, reducing complications that occur post-operatively. It acts locally; therefore, it has no systemic effects. Epidural anesthesia has reduced stress response as compared to other modalities of pain management.
Types of Pain
There are two kinds of pain, physiological and clinical. Physiologic pain is pain that comes and goes. It acts as a protective mechanism since it sends a message that there is something causing pain and; therefore, one has to remove the offending stimulation. Clinical pain, on the other hand, is pain arising from excessive sensitivity of a local area to painful stimuli, and this pain also spreads to localized tissues that are otherwise not injured. Surgery causes incision pain as a result of trauma to nerve endings and tissues. The resultant trauma causes overstimulation of pain receptors, and these then communicate the stimuli to the spinal cord, which then becomes hyperstimulated.
The resultant pain that is centralized is a kind of post-traumatic tension to the spinal cord. The central nervous system, consequently, interprets any stimulation as unpleasant, because it is overwhelmed. In addition to that, the pain can be referred to additional parts of the body. Pain is transmitted through A fibers and C fibers (Ganong, 2009, pp. 56). The A fibers are myelinated, and they are responsible for the fast transmission of pain. They transmit sharp pain. On the other hand, the C fibers are unmyelinated. They, therefore, transmit pain at a lower speed as compared to the A fibers. They transmit dull, throbbing pain (Gray, Standring, Ellis, & Berkovitz, 2007, pp. 1122).
The complications that arise from pain are multisystemic. In certain patients, the pain is very severe that they have to be confined to bed, and this causes further deterioration. First of all, there is the general stress response due to surgery. This is secondary to the release of inflammation mediators, and stress hormones like corticotrophin. The mediators cause the proliferation of inflammatory cells like neutrophils, and this leads to an increase in the metabolic rate (Schneider & Szanto, 2009, pp. 126). Another contributory factor to the increase in metabolic rate is the pyretic effect of cytokines that reset the hypothalamic thermostat. In addition to that, the cytokines lead to leaky vessels hence; water and sodium tend to be retained in the interstitial space.
Secondly, there are respiratory complications, which mainly occur, in patients that have had surgeries of the respiratory tract or those that are confined to bed. These include the lobular collapse of the lung, shallow breathing, cough suppression, and infections. Cough suppression results in the retention of respiratory secretions and this lead to susceptibility to infections. Lobular collapse is detected by reduced air entry. It can also lead to reduced oxygenation, and for this reason, lead to hypoxia. The patient may require being under oxygen support in case they develop a respiratory compromise. Prophylactic antibiotics may be used to reduce the chances of developing nosocomial infections (Jarrell & Carabassi, 2008, pp 121).
Thirdly, cardiovascular complications are inclusive of; tachycardia, hypertension, and increased cardiac work. The increase in cardiac work may lead to hypertrophy of myocardial muscles, angina, myocardial ischemia, and infarction of the cardiac vessels. Antihypertensive medication can also be used to reduce raised blood pressure (Hall and Guyton, 2011, pp. 224).
Pain can also cause immobility. This results in increased chances of thromboembolic episodes that arise secondary to vascular stasis. The most frequent sites of thrombus development are the deep veins of the lower limb. This is because the calf muscles aid in venous return to the heart and this occurs during mobility. The calf muscles especially the soleus muscle (which has been named the muscle pump), are involved in pumping blood back to the heart by their contraction and relaxation.
Vascular stasis is one of the factors that make up Virchow’s triad, which states the risk factors for thrombi formation. Once the thrombi have formed, they can dislodge, that is, embolize and move to another part of the body, for instance, the pulmonary trunk, where it causes cor pulmonale. In the heart, it can lead to myocardial infarction while in the brain; it can cause an infarction cerebrovascular accident.
Additionally, pain that causes immobility will cause musculoskeletal complications. For instance, due to reduced use of muscles, they tend to atrophy. This is indicated by reduced muscle bulk and power. Bones, on the other hand, undergo osteopenia due to increased osteoclastic activity with reduced osteoblastic activity. This is detected on the bone x-rays which show reduced cortical bone. This leads to easy fractures.
Last but not least, there are psychological complications. The pain causes constant anxiety and fear. This leads to insomnia, anger, and hostility to family members and other caretakers like medical personnel. Prolonged pain has been known to cause psychotic illness, and this may require the use of antipsychotic drugs (Coon and Mitterer, 2011, pp.56).
The disadvantages of epidural anesthesia are; firstly inadequate nerve block. This occurs in certain patients, and it can be remedied by attempting a second epidural (Karp, Morris & Jaslau, 2008, pp 49). Secondly, epidural anesthesia may cause respiratory compromise, and this means that the cough reflex and expectoration are reduced, hence, increased chance of infection. Thirdly, if the epidural needle goes beyond the epidural space, it may puncture the dura, and this will result in severe headaches in the patient (Sabiston & Townsend, 2008, pp. 78).
The puncture can also subsequently, lead to aspiration of cerebrospinal fluid. Another risk that arises with an epidural infusion of anesthesia is the risk of infection. The infection can spread to the adjacent meningeal membranes to cause meningitis. An epidural cannula can also cause injury to epidural vessels, and this will be diagnosed when a blood-stained tap is observed. The major complications are paralysis and death. Death occurs due to paralysis of the respiratory muscles; therefore, respiration is compromised leading to death.
Conversely, the advantages of epidural anesthesia are that, there is no effect on muscle power and sensation; hence, meaning that mobility is not affected. Epidural anesthesia is also effective. There is also reduced post-operative respiratory infection and problems. Finally, there is a reduced chance of the patient suffering a myocardial infection, and stress responses are also minimal.
Use of Epidural Analgesia
An epidural catheter should be labeled so that it can be differentiated from either a venous or an arterial catheter. To prevent infection, the catheter should not be left in situ for more than three days. During the change of a catheter, an aseptic technique should be used. This entails the use of sterile gloves and masks (Rosai & Ackerman, 2011, pp. 678). Any medication that is infused through the catheter should have no preservatives. During the replacement of a catheter, alcohol should not be used to sterilize the site of the catheter. The patient ought to be constantly assessed to ascertain that the epidural block is effective; this is to ensure that the patient does not suffer from poor pain management.
There should, hence, be continuous monitoring of the patient’s pain score. Ideally, the patient needs assessment at least thrice a day to ensure that pain management is effective. Pain is assessed after the patient has been asked to take a deep breath, move about, and cough. The pain is rated from 1-5 by the pain relief rating. The ideal rate is 4-5 because this allows the patient to undergo chest physiotherapy, and move about. In cases where pain management is poor, the epidural cannula should be checked to ensure that it is neither dislodged nor malpositioned. Pain that causes psychological changes should be indicative of poor pain management, and this warrants a change of analgesia.
It has been reported that when fentanyl or bupivacaine are used as anesthesia, they provide segmental pain relief, and so the anesthetist may be required to insert many cannulas. This method is preferred because it is more effective, and the dosage of the drugs used is less; hence, there are minimal side effects. These drugs have a reduced effect on respiratory function as compared to morphine and other opiate drugs.
In addition to that, the patient’s dermatomes should be regularly assessed for sensation. The sensory elements that are reviewed are, for example, cold, vibration, and pressure. If the sensation is affected the physician may be called in to review the patient and change the anesthesia used or the rate of infusion.
The patient should also be constantly evaluated for developing paraesthesia. This is done using the Bromage scale which grades paralysis from complete paralysis to partial weakness. The score ranges from one to six. One represents a complete block, where the patient cannot move the lower limb at all. Two represents the ability to move the feet alone. Three represents the ability to move the knees; it is a partial block. Four, on the other hand, represents the patient’s ability to fully flex their knees, but there is detectable weakness on hip flexion. Five corresponds to the hip flexion with no weakness while the patient is supine. Six represents the partial ability to bend the knees. Paralysis and sensory change are bad prognostic factors; hence they should be avoided (Constanzo, 2007, pp 79).
The infusion rate of the analgesia should be constantly monitored in case it is running too fast, therefore, causing cardiorespiratory compromise. Respiratory compromise may not necessarily manifest with decreased respiratory rate. It may manifest as sedation or altered mental status, for instance, the patient may be confused or delirious. Management entails reducing the infusion rate or changing the analgesic drug. Alternatively, if it runs too slowly, the patient may still be in pain.
The patient’s temperature should also be monitored closely because; a rise in the temperature would indicate infection (Marieb, 2006, pp. 76). Infection is also accompanied by a rise in respiratory rate and heart rate. Many patients have been observed to have raised body temperatures twenty-four hours postoperatively, and this may not raise concern among the medical staff. However, a patient who has persistent fever may be having bacteremia, and this may spread to the epidural site. Such patients may have their catheters removed after weighing the benefits and risks of having the catheter in-situ. The patient may also be given antipyretic medication to reduce the high body temperature. The most commonly used antipyretic medication is paracetamol (Finkel, Clark, and Cubeddu, 2009, pp.34).
The epidural site should also be constantly monitored, as it has been reported that thoracic catheters are more likely to dislodge as compared to lumbar ones. This can be reduced by enhancing the dressing on epidural sites. The catheter can also kink, become occluded, or the infusion pump can also malfunction. The management and prevention of such occurrences can be reduced by training the hospital staff. In addition to that, the site ought to be checked for inflammation. This may indicate that the aseptic technique was not used during the insertion of the catheter, movement around the insertion site, or other areas of infection. Management entails the use of an antiseptic to clean that area, but alcohol-based antiseptics should be avoided.
The patient should also be monitored closely lest they develop side effects due to the drugs used for analgesia. Pruritus and gastrointestinal symptoms are the common side effects. When non-steroidal anti-inflammatory agents are used, the patient may complain of epigastric pain that results due to gastric ulcers. Treatment of side effects may require the use of anti-histamines which are meant to reduce pruritus and epigastric pain. Adverse effects may warrant changing the analgesic drug.
In cases where the patients are on prolonged epidural medication and are confined to bed, they may require supportive treatment like catheterization and physiotherapy so that they do not get urinary tract infections and contractures (Goodman & Fuller, 2009, pp 87). To prevent bedsores, they should be advised to change their position at least every hour.
Possible Complications
Hypotension is described as a systolic pressure that is below 100mmhg. This may occur as a result of epidural infusion. The patient is, hence, hypotensive, and he requires fluid resuscitation. The best plasma expander is normal saline. Fluids should be judiciously administered to the patient to avoid fluid overload, which would lead, to heart failure. The patient may also be given adrenaline which is a vasoconstrictor, and this would raise the blood pressure (Lilley & Savoca, 2007, pp. 234). The rate of infusion should also be reduced to alleviate this complication.
The headache could be a result of a puncture of the dura during insertion of the cannula. The cannula can also migrate to puncture the dura, and this can cause aspiration of cerebrospinal fluid that would cause the resultant headache to stretch of the meninges. The brain is usually suspended in the skull by the cerebrospinal fluid. When cerebrospinal fluid leaks, the brain rubs against the skull and this causes stretching of the meninges causing the resultant headache, which is very severe and is not relieved by painkillers. The pain starts approximately twenty-four to forty-eight hours after insertion of the epidural catheter (Karp, Morris & Jaslau, 2008, pp 57).
The leakage of cerebrospinal fluid can also lead to vasodilation of blood vessels in the brain. This further worsens the headache which is front-occipital. The patient may require opiates to alleviate the severe pain.
When the brain sags, the cardiorespiratory centers which are at the base of the skull can herniate through the foramen magnum, and cause compromise of the cardiovascular and respiratory systems (Lehne, 2007, pp.56). In this situation, the patient may require ventilation and circulatory support to keep them from succumbing. The analgesia may also not be effective in alleviating pain; therefore, the dose should be increased, or the drug users should be substituted with another.
The analgesia may also cause blockage of nerves supplying the muscles, hence, causing weakness. The drug may require to be changed to alleviate this side effect, and the patient may require physiotherapy. In addition to these, the patient’s level of sedation should be monitored. Sedation manifests as an altered level of consciousness. A patient that presents with increased sedation may require supportive treatment like oxygen support, catheterization, and parenteral or nasogastric tube feeding. Sedation can also manifest as loss of sensation and movement.
The respiratory rate and arterial blood gases should be constantly be assessed. A rise in respiratory rate is a sign of anxiety, and the patient may require assurance that they will be alright. The most common complication that arises from tachypnea is respiratory alkalosis, and this then causes the patient to compensate by losing bicarbonate ions through the kidney. This then reduces the serum pH and alleviates alkalosis. He may also be given anti-anxiety medication; these would act to reduce the rise in respiratory rate (Katzung, Masters, and Trevor, 2009, pp. 678).
A cannula in-situ may develop a hematoma around it, especially if an epidural blood vessel is injured. The definitive management of a hematoma is drainage. In other cases, a patient may develop an abscess due to a lack of aseptic technique. An abscess requires incision and drainage. Systemic antibiotics should also be given to the patient (Finkel, Clark, and Cubeddu, 2009, pp.34).
Conclusion
In summary, the benefits of epidural analgesia outweigh the risks. The patients, however, require closer monitoring because of the complication that can arise secondary to epidural analgesia. The major complication that arises from epidural anesthesia is a spinal shock.
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