Postoperative Management and Pain Assessment: A Case Study

This case study discusses the postoperative management and pain assessment of an 83-year-old male patient who underwent total hip replacement surgery. It explores the drug ADME and alternative drugs for pain relief. The role of nurses in pain management and the importance of diet and rehabilitation are also examined.

Running head: CASE STUDY
CASE STUDY
Name of the Student:
Name of the University:
Authors note

1CASE STUDY
The following assignment is about Pasha Smirnov who is an 83-year-old male patient
who has gone through a total hip replacement or THR surgery. In this case, study the post-
operative management and pain assessment has been discussed in detailed. The case study’s
objective is to determine the drug ADME which is incongruous to Pasha’s case. The class of
drugs and its mechanism of action is aimed to be discussed in the following paragraphs.
Therefore, the main objective is to analyse the issues faced by Pasha and suggest any
alternative drugs available in this case. The drugs given to Pasha’s medical regime included
intravenous infusion of morphine, paracetamol, diclophenac and odansteron. The
pharmacological processes and the pharmacokinetic processes are an essential part when it
comes to drugs and their effects on the patient. Pasha has been already given the Patient
controlled Analgesic or PCA, with an infusion pump, but in the report, it has been mentioned
that he has been continuously facing problems of nausea and moderate pain by the pain
assessment tool. Nurses play a crucial role when it comes to therapeutic efficacy for the
patient. Therefore, the nurse’s role in pain management has been evaluated in this essay. In
this assignment alternatives to opioids has been aimed to research which can provide efficacy
with less side effects. Diet and rehabilitation regime are important aspects to one’s quick
recovery and well-being; hence, the correct diet is vital in Pasha’s diet regime.
In the given Case Study, Pasha Smirnov, who has a past history of osteoarthritis and
has gone through a total hip replacement surgery. The total hip replacement is an effective
surgical procedure in case of osteoarthritis (Dumolard, Gök and Le 2017). After surgery
nausea and constipation are the most common effect. There has been a post-operative
medicine regime that has to be followed by Pasha. In this case study, the pharmacological
processes and the drug interactions which has its synergistic and additive effects has been
analysed which can cause physiological reciprocations. The motive is to understand the
nurse’s role in post-operative management as well as pain management in a therapeutic way.

2CASE STUDY
The main objective of this study is to research the current alternative drugs which can be
used, in this case, analogous to Pasha Smirnov’s case. The follow-up visits by the patient and
patient education in this case will be also be discussed.
According to the patient’s current drug intake regime the ADME for Morphine (IV-
PCA): A morphine is an opioid drug which is used to relieve all types of pain and binds with
mu receptor (Garimella and Cellini 2013). The absorption of drug morphine intravenous, in
patient-controlled analgesic 10 mg per 10 ml, is quick because it is intravenous and it is
absorbed directly in the blood. Intravenous patient-controlled analgesia (IV-PCA) is a widely
used post-operative medication for pain control (Koh et al. 2015). As the route of absorption
is via IV administration, it could be understood that the onset of the drug is rapid. Pasha has
been given paracetamol as well which is 1 gm every six hours and a day. In a post-operative
treatment and management, this inclusion of paracetamol along with the IV morphine
(inpatient control analgesia) acts as a synergistic effect in reducing pain. Going by Pasha’s
prior medical history of severe osteoarthritis, administration of paracetamol in Pasha’s case,
can also help in osteoarthritis and prevent any infection inpatient (Machado et al. 2015).
According to Pasha’s case report, he had been experiencing a persistent record of hip
and joint pain for the last five years hence due to severe Osteoarthritis he went for total hip
replacement (THR). Therefore, paracetamol will also reduce the lower back pain
accompanying the post-operative management (Saragiotto et al. 2016). The application of
paracetamol along with the intravenous morphine will also enhance the efficacy of the drug
(Ceelie et al. 2013). The patient has been administered with Diclofenac with 50 mg three
times a day whenever required depending upon the condition of the patient. The
administration of Diclofenac helps in alleviating the pain, and in Pasha’s case it would help in
acute and chronic pain management as it is a non-steroidal anti-inflammatory drug (Pogatzki-

3CASE STUDY
Zahn, Chandrasena, and Schug, 2014). Along with managing the chronic pain, it will also
help in Pasha’s osteoarthritis (Gibofsky et al. 2014).
The morphine drug is distributed widely in the body. The metabolism takes place
mainly in the liver (Tzvetkov et al. 2012). There is a probability of soft tissue irritation due to
metal, which is a common cause of chronic pain after THA (Classen et al. 2013). Hence,
MRI scan ultrasound scan can be done to analyse the situation further. Infections should be
controlled that can also possibly cause chronic pain (Argoff 2014). The metabolic conversion
that takes the place of morphine yields two metabolites morphine-3-glucuronide (M3G) and
morphine-6-glucuronide (M6G). The elimination of the active metabolites takes place via
renal routes. The bioavailability of the drug since it is administrated intravenously it is 100
per cent. The peak plasma concentration is in 20 minutes in Intravenous drug administration
with total dose of 12mg per hour. The drug has a half-life of 1 to 2 hours. In gastrointestinal
tract diclofenac is absorbed completely hence, there is a rapid effect with a half-life of two
hours and metabolised in the liver.
Since Pasha has been administered with NSAIDs, and drugs like morphine and
diclophenac, as a result, Pasha may have a high tendency to have nausea and frequent
vomiting. Hence, the administration of Odansteron has been advocated, which will relief the
patient with the feeing nausea and vomiting. It is effective in post-operative cases (De
Oliveira Jr et al. 2013).
The drug is metabolised in the liver, and it is eliminated via the kidney. It is a
common phenomenon in post-operative management which is observed in patients.
Commonly known as Post-Operative Nausea and Vomiting (PONV) and hence
administration of antiemetic is significant (Gan et al. 2014). It is to be noted that in case
lower hip post-operative treatment that the patient can develop deep vein thrombosis and

4CASE STUDY
pulmonary embolism hence timely thromboprophylaxis of enoxaparin is required (Fuji et al.
2014). Pasha is given Lactulose 15 ml two times a day, in this scenario, it is given to him as a
post-operative medicament (Lessen et al. 2013). The drug is metabolised by the colon and
enteric bacteria, but the drug’s bioavailability is less.
The morphine drug has the following interactions with the benzodiazepines. When
the morphine is administered with benzodiazepines, it has additive as well as pharmacologic
effect. Drugs like Diazepam and anti-hypertensive agents give a synergistic effect. In a
research, it was seen that there is a synergistic effect with clonidine (Stone et al. 2014).
Distribution of diclofenac is rapid in the body, and there is an additive effect along with
paracetamol. This will help Pasha to relieve his pain, and since, it is Pasha’s post-operative
regime it will help him overcome pain in the hip wound along with opioids (Flores-Ramos
and Díaz-Reval 2013). It has been mentioned in the case report that Pasha as a post-operative
measure is wearing anti embolism stockings or AES. AES along with enoxaparin is an
anticoagulant with low molecular weight that is used to treat deep vein thrombosis.
After understanding Pasha’s current medicinal regime in detail with respective to its
pharmacokinetics involving ADME, bioavailability and the additive as well as its synergistic
effect in the previous paragraph. A detailed view and analysis would be given about
pharmacologic as well as the drugs adverse effect on Pasha’s regime will be discussed. By
the above pharmacokinetic evaluation, it can be understood that Pasha has been administered
with patient-controlled analgesic effect. In Pasha’s case, it could be analysed that he has mild
pain while mobilising which is recorded as 5 to 6. Morphine opioid receptors are widely
spread across the central nervous system and pharmacologically acts on the μ (mu) opioid
receptor subtype receptor in the brain with high intensity on the amygdala (on the posterior
side) putamen, thalamus as well as hypothalamus. Pasha according to the report is only able

5CASE STUDY
to manage few amounts of liquids and fluids because of persistent nausea which can be due
to morphine (Tammachote et al. 2013). Although it has not been mentioned in the report but
in the case of Pasha, there can be severe respiratory depression as well. Therefore, the patient
should be advised to inhale deeply. Pasha had not opened his bowels since the past three days
after surgery, administration of morphine caused constipation due to high binding of the
opioid receptor in the GI tract (Devillers et al. 2013). Hence, prophylactic use of a laxative is
required in Pasha’s case.
As discussed before, the administration of paracetamol is beneficial in Pasha’s case as
a postoperative medication, especially in people with osteoarthritis (Machado et al. 2015). In
a report, it is given that the administration of morphine and diclophenac as a postoperative
medication can reduce the pain significantly (Imantalab et al. 2014). The combination of
opioids along with the paracetamol and diclophenac can help in reducing pain, and it can also
help reduce in consumption and dependency of the opioids (Alliman et al. 2014). Diclofenac
and Paracetamol have two very different way of mechanism of action as Paracetamol is a
COX (COX-1, COX-2 and COX-3) inhibitor acting on the central nervous system; however,
it is not used as an anti-inflammatory and it is well tolerated in the body (Jóźwiak-Bebenista
and Nowak 2014).
In the case of diclophenac, it would be acting as a non-steroidal anti-inflammatory
drug with COX-1 and COX-2 inhibitor (Aeilo et al. 2014). However, in Pasha’s case, he is
facing pruritus in his trunk and back, it could be assorted as a side effect of morphine
administration (Kumar and Singh 2013). Moreover, paracetamol can cause an adverse effect
hypersensitivity reaction (Biswal and Sahoo 2014). Dyspepsia found in Pasha’s case could be
due to the administration of diclophenac, as gastrointestinal irritation observed in many cases.
According to Pareek and Chandurkar (2013), aceclofenac is a better drug administration than
diclophenac in terms of Gastrointestinal tolerability as well as for the betterment

6CASE STUDY
osteoarthritis. To curb the frequent vomiting and in Pasha’s case, he was given odansetron 8
mg twice a day, which is a selective and competitive serotonin 5-HT3 receptor antagonist.
Pasha was further given Lactulose to prevent constipation, twice a day, however, this can
cause dyspepsia as well. In a report Lactose in combination with meal has elevated functional
dyspepsia with patients with irritable bowel syndrome or IBS (Pohl et al. 2019).
The six R’s of nursing is very important so that there is proper delivery of
medications and nursing supervision in accordance with the patient’s consent. Hence,
Pasha’s case requires skilled nursing attention as well as proper anaesthesia, which require
proper care and monitoring so that the patient can be relieved of pain. As a post-operative
measure, in Pasha’s case, he has to be taken in to post anaesthesia care unit (PACU),
however, and three days have already passed. Pasha’s recovery in any other process is a
collaborative process, and there is an involvement of nurses, doctors and other clinical staffs
who need to maintain a proper medicine and care regime so that Pasha could recover fast.
Pasha has not passed bowel since the day of the operation (three days have already passed)
and therefore, it could be noticed that there is a need for laxative here. Hence, in this case
Pasha should be administered laxative immediately to avoid any other gastrointestinal
complication.
In addition to that, aceclophenac could be administrated instead of diclophenac as an
NSAID, as per the literature review the gastrointestinal tolerability and it is also applicable in
case of osteoarthritis (Pareek and Chandurkar 2013). In Pasha’s case, even after
administration of odansetron, there is an existence of persistent nausea. It is a very common
case when it comes to post-operative nausea and vomiting due to anaesthesia, and surgery
and it can be due to the opioids and non-steroidal ant-inflammatory drugs. As post-operative
management, lower doses of opioids should be given and the alternative medications for
opioid analgesic can be given whenever found appropriate. Anticholinergic drugs,

7CASE STUDY
antihistamines and dopamine antagonists could be given. In Pasha’s case, pain is moderately
present, and on the numerical scaling tool, while mobilising rated from 5-6. According to
Apfel et al. (2013), recommended I.V. administration of acetaminophen as post-operative
requirement. In this case, it would reduce the nauseating effects of opioids-oriented drugs. In
Pasha’s case the administration of analgesic is through an infusion pump (PCA), and
therefore, the patient has to be vigilantly monitored by the nurse. However, according to
Tetsunaga et al. (2015), it was found that continuous femoral nerve block (CFNB), provided
better pain relief, with lower side effects. Hence, as per research it could be adapted as an
alternative with people with acute nausea after morphine IV administration.
Primarily nurses are in charge of the pain management and assessment. Therefore, it
is imperative for the nurses to assess the descriptive version of Pasha’s pain. Apart from the
medicine management, the supervising nurse has to check the vital signs of Pasha from time
to time and the nurse has to follow and monitor the PCA, the nurse should maintain the
patients vital properly and communicate with Pasha so that there is a record of Pasha’s
perspective, this will help the doctors in clinical analysis. As Pasha has been given morphine,
there can be possibility of respiratory depression and hence, he should be advised to breathe
deeply. As per case study, it can be understood that the persistent nausea in Pasha’s case is
there even today, therefore Naloxone could be given to minimise the effect of morphine
which is an opiate drug. Instead of morphine, there can be an administration of 25 mg
pethidine (Intravenous bolus, which can be administered half or about a quarter of the dose).
Pasha has also not passed bowel since the THR surgery hence, his advised diet should contain
foods that are high in fibre along with the supplementation of liquids (water and fresh juices)
and fresh vegetables and fruits (Who.int, 2019). There should be continuous monitoring of
Pasha’s blood pressure, temperature and respirations.

8CASE STUDY
To avoid the surgical site infection, Pasha should be monitored for normothermia,
therefore, the should be provided with warm air units and hyperthermia blankets to obtain
normothermia (Mori. Hageman and Zimmerly 2017). According to the Alert, Confusion,
Verbal, Pain, and Unresponsive tool, he responded as alert (RCP London 2019). Since Pasha
is alert, therefore, Patient education can be initiated with the patient along with a family
member. After the bowel movement, there could be a planned discharge decided by the
doctor. Gradually Pasha, should be assisted to rehabilitation and physiotherapy exercises after
proper medication as discussed above. Pasha should be given information about the
precautions of the hip movements, and in his case, it is advisable not to bend forward. To
control any kind of swelling compression, stocking are already there in Pasha’s regime and
hence, it would be advisable for Pasha to wear the compression stockings. Moreover, to avoid
postoperative stiffness and intra articular adhesions, there should be early range of motion or
ROM (Enseki and Kohlrieser 2014). In his postoperative rehabilitation regime Pasha should
be given Pendulum or cicumduction ROM exercises. Follow up regimes should mentioned to
Pasha and assistance for dressing should be done accordingly. The dressings and wound
healing of the Pashas should be taken care of by the supervising nurse. Most important part of
the nursing care is therapeutic listening to the patient, with asking open end questions and
there should be well balance nurse patient understanding and relationship (Dumolard, Gök
and Le 2017).
In conclusion to the above literature review and discussion about Pasha Smirnov’s
case it could be inferred that, as a post-operative care, there has been administration of
medications. The medicine’s drug distribution and metabolism has been discussed in detail
along with Pasha’s symptoms after his THR surgery. After doing a thorough research
pharmacological research, as a post-operative medication morphine was administrated along
with the administration of paracetamol, diclophenac and odansetron. In the pharmacokinetic

9CASE STUDY
process, the drug administration, bioavailability as well as the synergistic and additive effects
of the drug has been well explained. Furthermore, the pharmacology of the drugs in Pasha’s
case that have potential adverse effects have been also discussed. Pasha’s given drug regime
has been thoroughly discussed with the potential adverse effects of the drugs. According to
the report, it could be understood that Pasha had nausea and vomiting, along with mild
dyspepsia. As explained nausea and vomiting which is common could be a potential adverse
effect of morphine. Furthermore, the dyspepsia can be also an adverse effect of paracetamol
and diclophenac. Though there is an administration of odansetron, the constipation can cause
nausea as well. In Pasha’s case, even after three days there is constipation, and laxative
supplementation has been advised. Acelcofenac instead of diclophenac has been advised, as it
has improved gastric tolerance. The morphine can cause further respiratory because opioids
acts on the binding side of receptors. Hence, Pasha has been advised to breathe deeply. The
nursing care regime along with patient care has also been mentioned. Pasha’s diet should
include high fibre diet with the intake of lots of fluids along with fruits and vegetable. It is to
be understood that implementation of lactulose can further increase constipation of Pasha. As
a vigilant supervision the nurse should keep proper documentation and record of Pasha’s
vitals like the temperature, respirations and the blood pressure. In the above discussion, by
understanding Pasha’s current status it could be understood that the tendency to vomit has
decreased but there has been persistent nausea. Hence, from the literature review some other
alternatives has been mentioned with respect to morphine medication. For instance, I.V.
administration of acetaminophen and continuous femoral nerve block (CFNB) has been
proved to be better analgesic with lower side effects as compared to morphine, which is still
persistent in Pasha’s case. Furthermore, Naloxone can also be given to the patient instead of
morphine. As soon as Pasha overcomes the nauseating effect, he should be encouraged by the
nurse to go through certain exercise regimes that is very important with respect to the post-

10CASE STUDY
operative measurement to avoid any kind of stiffness. The supervising nurse should give
Pasha the patient education about his follow up visits and time to dressing regime as well as
the medication direction.
References
Aielo, P.B., Borges, F.A., Romeira, K.M., Miranda, M.C.R., Arruda, L.B.D., Drago, B.D.C.
and Herculano, R.D., 2014. Evaluation of sodium diclofenac release using natural rubber
latex as carrier. Materials Research, 17, pp.146-152.
Alimian, M., Pournajafian, A., Kholdebarin, A., Ghodraty, M., Rokhtabnak, F. and
Yazdkhasti, P., 2014. Analgesic effects of paracetamol and morphine after elective
laparotomy surgeries. Anesthesiology and pain medicine, 4(2).
Apfel, C.C., Turan, A., Souza, K., Pergolizzi, J. and Hornuss, C., 2013. Intravenous
acetaminophen reduces postoperative nausea and vomiting: a systematic review and meta-
analysis. PAIN®, 154(5), pp.677-689.
Argoff, C.E., 2014. Recent management advances in acute postoperative pain. Pain
Practice, 14(5), pp.477-487.
Biswal, S. and Sahoo, S.S., 2014. Paracetamol induced Stevens‐Johnson syndrome–toxic
epidermal necrolysis overlap syndrome. International journal of dermatology, 53(8),
pp.1042-1044.
Ceelie, I., De Wildt, S.N., Van Dijk, M., van den Berg, M.M., Van Den Bosch, G.E.,
Duivenvoorden, H.J., De Leeuw, T.G., Mathôt, R., Knibbe, C.A. and Tibboel, D., 2013.
Effect of intravenous paracetamol on postoperative morphine requirements in neonates and
infants undergoing major noncardiac surgery: a randomized controlled trial. Jama, 309(2),
pp.149-154.

11CASE STUDY
Classen, T., Zaps, D., Landgraeber, S., Li, X. and Jäger, M., 2013. Assessment and
management of chronic pain in patients with stable total hip arthroplasty. International
orthopaedics, 37(1), pp.1-7.
De Oliveira Jr, G.S., Castro-Alves, L.J.S., Ahmad, S., Kendall, M.C. and Mccarthy, R.J.,
2013. Dexamethasone to prevent postoperative nausea and vomiting: an updated meta-
analysis of randomized controlled trials. Anesthesia & Analgesia, 116(1), pp.58-74.
Devilliers, M., Busserolles, J., Lolignier, S., Deval, E., Pereira, V., Alloui, A., Christin, M.,
Mazet, B., Delmas, P., Noel, J. and Lazdunski, M., 2013. Activation of TREK-1 by morphine
results in analgesia without adverse side effects. Nature communications, 4, p.2941.
Dumolard, P., Gök, M. and Le, N., 2017. Nurses' responsibilities in postoperative pain
management following total hip arthroplasty.
Enseki, K.R. and Kohlrieser, D., 2014. Rehabilitation following hip arthroscopy: an evolving
process. International journal of sports physical therapy, 9(6), p.765.
Flores-Ramos, J.M. and Díaz-Reval, M.I., 2013. Opioid mechanism involvement in the
synergism produced by the combination of diclofenac and caffeine in the formalin
model. ISRN Pain, 2013.
Fuji, T., Fujita, S., Kawai, Y., Nakamura, M., Kimura, T., Kiuchi, Y., Abe, K. and Tachibana,
S., 2014. Safety and efficacy of edoxaban in patients undergoing hip fracture
surgery. Thrombosis research, 133(6), pp.1016-1022.
Gan, T.J., Diemunsch, P., Habib, A.S., Kovac, A., Kranke, P., Meyer, T.A., Watcha, M.,
Chung, F., Angus, S., Apfel, C.C. and Bergese, S.D., 2014. Consensus guidelines for the
management of postoperative nausea and vomiting. Anesthesia & Analgesia, 118(1), pp.85-
113.

12CASE STUDY
Garimella, V. and Cellini, C., 2013. Postoperative pain control. Clinics in colon and rectal
surgery, 26(03), pp.191-196.
Gibofsky, A., Hochberg, M.C., Jaros, M.J. and Young, C.L., 2014. Efficacy and safety of
low-dose submicron diclofenac for the treatment of osteoarthritis pain: a 12 week, phase 3
study. Current medical research and opinion, 30(9), pp.1883-1893.
Grenald, S., Wang, Y., Young, M., Stark, J., Hu, J. and Vanderah, T., 2015. (368) Synergistic
drug interaction between morphine and a cannabinoid receptor 2 agonist in a model of
neuropathic pain. The Journal of Pain, 16(4), p.S68.
Imantalab, V., Mirmansouri, A., Sedighinejad, A., Nabi, B.N., Farzi, F., Atamanesh, H. and
Nassiri, N., 2014. Comparing the effects of morphine sulfate and diclofenac suppositories on
postoperative pain in coronary artery bypass graft patients. Anesthesiology and pain
medicine, 4(4).
Jóźwiak-Bebenista, M. and Nowak, J.Z., 2014. Paracetamol: mechanism of action,
applications and safety concern. Acta poloniae pharmaceutica, 71(1), pp.11-23.
Koh, J.C., Lee, J., Kim, S.Y., Choi, S. and Han, D.W., 2015. Postoperative pain and
intravenous patient-controlled analgesia-related adverse effects in young and elderly patients:
a retrospective analysis of 10,575 patients. Medicine, 94(45).
Kumar, K. and Singh, S.I., 2013. Neuraxial opioid-induced pruritus: an update. Journal of
anaesthesiology, clinical pharmacology, 29(3), p.303.
Lessen, K., Coolsen, M.M., Slim, K., Carli, F., de Aguilar-Nascimento, J.E., Schäfer, M.,
Parks, R.W., Fearon, K.C., Lobo, D.N., Demartines, N. and Braga, M., 2013. Guidelines for
perioperative care for pancreaticoduodenectomy: Enhanced Recovery After Surgery
(ERAS®) Society recommendations. World journal of surgery, 37(2), pp.240-258.

13CASE STUDY
Machado, G.C., Maher, C.G., Ferreira, P.H., Pinheiro, M.B., Lin, C.W.C., Day, R.O.,
McLachlan, A.J. and Ferreira, M.L., 2015. Efficacy and safety of paracetamol for spinal pain
and osteoarthritis: systematic review and meta-analysis of randomised placebo controlled
trials. bmj, 350, p.h1225.
Mori, C., Hageman, D. and Zimmerly, K., 2017. Nursing Care of the Patient Undergoing an
Anterior Approach to Total Hip Arthroplasty. Orthopaedic Nursing, 36(2), pp.124-130.
Pareek, A. and Chandurkar, N., 2013. Comparison of gastrointestinal safety and tolerability
of aceclofenac with diclofenac: a multicenter, randomized, double-blind study in patients
with knee osteoarthritis. Current medical research and opinion, 29(7), pp.849-859.
Pogatzki-Zahn, E., Chandrasena, C. and Schug, S.A., 2014. Nonopioid analgesics for
postoperative pain management. Current Opinion in Anesthesiology, 27(5), pp.513-519.
Pohl, D., Van Oudenhove, L., Törnblom, H., Le Nevé, B., Tack, J. and Simrén, M., 2018.
Functional dyspepsia and severity of psychologic symptoms associate with postprandial
symptoms in patients with irritable bowel syndrome. Clinical Gastroenterology and
Hepatology, 16(11), pp.1745-1753.
RCP London, 2019. National Early Warning Score (NEWS) 2. [online] Available at:
https://www.rcplondon.ac.uk/projects/outputs/national-early-warning-score-news-2
[Accessed 1 Mar. 2019].
Saragiotto, B.T., Machado, G.C., Ferreira, M.L., Pinheiro, M.B., Shaheed, C.A. and Maher,
C.G., 2016. Paracetamol for low back pain. Cochrane Database of Systematic Reviews, (6).
Stone, L. S., German, J. P., Kitto, K. F., Fairbanks, C. A., & Wilcox, G. L. (2014). Morphine
and clonidine combination therapy improves therapeutic window in mice: synergy in
antinociceptive but not in sedative or cardiovascular effects. PLoS One, 9(10), e109903.

14CASE STUDY
Tammachote, N., Kanitnate, S., Manuwong, S., Yakumpor, T. and Panichkul, P., 2013. Is
pain after TKA better with periarticular injection or intrathecal morphine?. Clinical
Orthopaedics and Related Research®, 471(6), pp.1992-1999.
Tetsunaga, T., Sato, T., Shiota, N., Tetsunaga, T., Yoshida, M., Okazaki, Y. and Yamada, K.,
2015. Comparison of continuous epidural analgesia, patient-controlled analgesia with
morphine, and continuous three-in-one femoral nerve block on postoperative outcomes after
total hip arthroplasty. Clinics in orthopedic surgery, 7(2), pp.164-170.
Tzvetkov, M.V., dos Santos Pereira, J.N., Meineke, I., Saadatmand, A.R., Stingl, J.C. and
Brockmöller, J., 2012. Morphine is a substrate of the organic cation transporter OCT1 and
polymorphisms in OCT1 gene affect morphine pharmacokinetics after codeine
administration. Biochemical pharmacology, 86(5), pp.666-678.
World Health Organization. 2019. Postoperative Care. Available at:
https://www.who.int/surgery/publications/Postoperativecare.pdf [Accessed 1 Mar. 2019].