Outcome following the introduction of a procedure specific pain management program for caesarean section

Based on the results of a prospective audit conducted in 2014 among 310 post caesarean section patients (Group A) at Tuen Mun Hospital, Hong Kong, a procedure specific postoperative pain management programme was implemented. To complete the audit cycle, a second prospective audit was conducted in 2015 among 332 patients (Group B). The proportion of patients with severe pain (VAS>=7/10) reduced significantly from 55.5% (Group A) to 23.0% (Group B) (p


Introduction
Post caesarean section (CS) patients usually suffer from moderate to severe pain postoperatively. Traditionally opioid is used for analgesia. However opioid use is associated with many side effects and long term problems, e.g. dependence, drug abuse. The Joint Commission 1 , recognizing the potential danger of opioid use, issued a Sentinel Event Alert and made recommendations on the safe use of opioids, including the use of multimodal analgesia. Multimodal analgesia is the combination of different classes of analgesics in optimal dosages that maximize efficacy and minimize side effects. So far published meta-analyses focused on the combination of two analgesics 2,3,4,5 which do not fully reflect our common practice of using 3 or more analgesics. Moreover, the data is not procedure specific. Since we now have evidence to suggest that the efficacy of analgesic agents differ in different surgical settings 6 , further studies are needed to prove its effectiveness.
Postoperative pain therapy should be procedure specific for several reasons. Firstly, the nature of surgery influences the type, location, intensity and duration of pain. Secondly, the efficacy of different analgesics differs between different procedures. 6 Thirdly, the risks of analgesic techniques should balance against the benefits of pain therapy outcomes and this risk to benefit ratio depends on the type of procedure (e.g. Epidural analgesia offers complete analgesia after CS; however, its use is associated with motor impairment and urinary retention which affect breastfeeding and rehabilitation). Fourthly pain assessment should be procedure specific. (e.g. In classical incision for CS, assessing dynamic pain score during coughing is important as inadequate pain relief could lead to cardiopulmonary complications).
Tuen Mun Hospital (TMH) is the largest regional hospital in the New Territories West Cluster (NTWC) in Hong Kong. We have more than 5500 deliveries a year and the rate of caesarean section is about 27%. As part of the Quality Improvement Program, we introduced procedure specific pain management programme (PSPMP) in 2015 and evaluated its effectiveness by performing audits.

Methods
This prospective survey was conducted in the postpartum obstetric ward. Our institutional ethics committee was consulted and this project was approved as a quality assurance activity. Patients were followed up by pain nurses during work days in the 3 months review period. Two structured questionnaires were designed. One to be filled on postoperative day 1 to collect patient information, the type of analgesics that were prescribed and pain score in the first 24hrs. The second one was filled on postoperative day 2 or 3 to assess the overall pain management service.

Standardise the use of spinal morphine
In Group A, about 11.2% of patients received fentanyl. Since no regular analgesics were administered postoperatively, the worst 24hr visual analogue scale (VAS) was 7 (IQR: 5-8  With significant improvement in parameters 2 to 6 ( Table 4), the second set goal was achieved in Group B.
C. Analgesia related side effects (Table 5) Overall, there was no significant difference in the incidence of side effects in Group A and B (p=0.339). When looking into subgroups, the incidence of pruritus was slightly increased in Group B (p<0.001). This increase was expected because more patients now received spinal morphine (88.5% of patients had spinal morphine in Group A versus 99.3% in Group B).

Discussion
An ideal perioperative pain programme should be evidence-based, procedure specific and cost effective.

Principles behind the design of PSPMP a) Multimodal analgesia administered at regular intervals with prn analgesics
The key concept of 1986 WHO 11 analgesic ladder is by mouth, by the clock, by the ladder and for the individual. Paracetamol and non-steroidal anti-inflammatory agents (NSAID) are good at treating mild to moderate pain. Opioid should be the next step for patients with moderate to severe pain. The route of administration should be appropriate and should be administered orally wherever possible. Regular analgesics should be given.
Apart from treating pain according to its pain intensity, it is wise to match the analgesic with the underlying pain pathophysiology, e.g. NSAID reduces visceral pain originating from the uterus and complements the somatic wound pain relief from the opioid. It is opioid sparing and limits the opioid related adverse effects. Multimodal therapy should always be considered instead of using stepwise increase in a single analgesic. The use of RA wherever possible is now the standard anaesthetic care in CS. Survey showed that RA was increasingly used for elective CS from 32% in 1982 12 to 91% in 2000 13 and this trend may be responsible for the decline in maternal mortality due to anaesthesia, from 7.2 (1982-1984 report) 14 to 3 deaths per million maternities (2000-2002 report) 15 .
Apart from giving multimodal analgesia at a regular interval, prn medication for breakthrough pain is required to address the transient flare of pain on top of background pain. After optimizing the background analgesia, prn analgesics could provide a better dynamic pain relief and may facilitate early mobilization and rehabilitation.

b) Some non-opioid analgesic adjuncts
Preoperative 600mg gabapentin reduces post CS pain on movement at 24hrs but may result in severe sedation 16 . Neuraxial neostigmine and clonidine enhance postoperative analgesia. Side effects include prolonged motor blockade, nausea and vomiting in neostigimine use 17 and unacceptable hypotension, sedation, bradycardia, vomiting and prolonged motor block 18 in clonidine use. Dexamethasone (1.25 -20mg) 19 had been shown to decrease VAS at 24hrs, decrease pain on movement and decrease morphine consumption, decrease nausea and vomiting without increasing the rate of infection. Postoperative hyperglycemia may occur. Although these adjuvants showed promising results, they were not considered in our analgesic regime because of the side effects.
Regional block, for instance, TAP has opioid sparing effect . One study showed that TAP together with intrathecal opioid did not improve the outcome as compared to using intrathecal opioid alone. 20 So TAP is considered only in GA group or when spinal morphine is contraindicated.
We did encounter some resistance during the change in practice. We identified in Group A that 18.4% of patients were prescribed with prn pethidine. Pethidine during breastfeeding was not recommended because norpethidine would accumulate in breast milk with repeated use and had a low neonatal elimination. Finally, the team agreed on the change. Performing sTAP was another hurdle. Our team gained the consensus that it could save time if surgeon performs sTAP. In addition, sTAP could help to extend anaesthesia time in case when operation is long and spinal anaesthesia wears off.
There are some limitations. First of all, this is a sequential survey. The patients are not randomised and the observers cannot be blinded. Secondly, there are some missing data in both surveys, especially the second questionnaire. We managed to decrease the missing data in Group B from 37% to 29.5%.

Conclusion
With team effort, we managed to obtain more than 50% reduction in patients with severe pain in the first 24hrs and a positive increase in patient satisfaction. There is still room for improvement. 23% of post CS patients still had severe pain and 0.7% of patients were dissatisfied with the pain service in Group B. To sum up, pain management protocol should be procedure specific and multidisciplinary teamwork ensures its success.