Ineffective pain management in the postoperative period leads to untoward consequences like slower recovery and increased cost of care. Optimal pain management modalities enable earlier mobilization and ease of performing physical therapy with resultant early functional recovery. Recent decades have seen a surge of research directed towards improvement in the quality of postoperative pain relief with special focus on procedure specific pain management. Bulk of this research has originated from the developed world.
Systematic reviews are now being carried out in health care systems to get the best evidence for decision making and to subsequently include the researched modality/intervention in the clinical practice. Two main purposes of a systematic review are to establish the extent to which existing research has progressed toward explaining a problem, and to clarify the extent to which this evidence explains a new or existing question. The purpose of this systematic review is to deliver a meticulous summary of all the available RCTs performed in LMIC over the last decade for the management of postoperative pain in adult patients, to scrutinize the types of modalities being used in LMIC for postoperative pain relief, and to compare these modalities with those being used in the developed world.
The PROSPECT is an international collaboration of anaesthesiologists and surgeons. The PROSPECT aims to provide healthcare professionals with practical procedure-specific pain management recommendations formulated in a way that facilitates clinical decision-making across all the stages of the perioperative period [63]. For postoperative pain management for laparoscopic cholecystectomy procedure, PROSPECT [64] recommends multimodal analgesia including wound infiltration with long acting local anaesthetic (LA), intraperitoneal infiltration of LA or both, paracetamol, COX-2 selective inhibitors, NSAIDs, and opioids for rescue analgesia. Four out of 11 RCTs from LMIC used regional blocks, which are neither recommended, nor not-recommended in PROSPECT. However, that can be due to PROSPECT recommendations being formulated in 2005 while use of abdominal wall blocks is rather a recent phenomenon. Intraperitoneal infiltration of LA was studied in three instances. One trial compared LA infiltration of incisional wounds with abdominal plane blocks. Oral Pregabalin, Cox-2 inhibitor, and Gabapentin were also studied. Majority [five] RCTs used TAP blocks for the study group, intraperitoneal infiltration with LA in three, and gabapentinoids in three. Usual care or control groups received either TAP block at a different level than the study group [subcostal vs. conventional], different drugs or different concentrations of the same drugs. LA infiltration of the surgical wounds was employed in two control groups while celecoxib and alprazolam were used for two. One trial used placebo for control group in place of the studied modality. All trials used multimodal analgesia for pain management overall, which is according to the international recommendations.
Thoracotomy is considered one of the most painful surgical procedures. Inadequate pain relief after thoracotomy can result in postoperative pulmonary complications. Considering multifactorial nature of thoracotomy, a single modality cannot provide adequate pain control. The management of pain after thoracotomy requires a multimodal approach incorporating regional and systemic analgesia to targets multiple sites [65]. Regional analgesia is highly recommended with non-steroidal anti-inflammatory drugs (NSAIDs), paracetamol, opioids and other adjuvants for the pain following thoracotomy. Analgesic effect of paracetamol with NSAIDs is additive. None of the RCTs used NSAIDs and paracetomol for post thoracotomy pain.
Continuous thoracic epidural analgesia is recommended by PROSPECT for postoperative pain management following laparotomy, ensuring an appropriate level according to the site of incision [63]. A combination of local anaesthetic agent and an opioid for the epidural infusion has better analgesic efficacy compared to either agent alone. When the patient does not receive an epidural due to contra-indication or lack of feasibility, strong opioids using intravenous patient controlled analgesia (IV PCA) are recommended for high intensity pain as part of a multimodal regime. Multimodal analgesia in such cases may include non-steroidal anti-inflammatory drugs, paracetamol and intravenous lignocaine. Pre-peritoneal infusion of local anesthetic is recommended in patients who have not received an epidural. The RCTs s performed on postoperative pain relief in LMIC have employed multimodal analgesia in all cases as recommended for these procedures. Thoracic epidural was used in five of the 11 trials, while PCA was used in two. Majority RCTs [five] used thoracic epidural followed by TAP block [three]. In the case of usual care or control groups, thoracic epidural was employed but using either a different drug or a different concentration, while IV PCA was used for two control groups. Placebo was used in the control groups in three studies, replacing the studied modality. Abdominal wall blocks were employed in five studies, which are not part of the PROSPECT recommendations. As pointed out above, abdominal wall blocks have come in vogue after the PROSPECT recommendations. Since multiple and varied pain relieving modalities have been employed and compared in different studies, it is difficult to compare the results with the current recommendations.
Multimodal analgesia is recommended for postoperative pain relief following total abdominal hysterectomy (TAH). For severe pain, PROSPECT recommends strong opioids using PCA along with NSAIDs such as Diclofenac Opioids can be administered as a continuous infusion, when PCA is not feasible. Weak opioids can be substituted along with paracetamol and NSAIDs when pain decreases to moderate intensity [66]. Though epidural analgesia is not recommended for routine use, it is considered useful for high-risk patients undergoing TAH. In both the RCTs conducted in LMIC on post-hysterectomy pain, multimodal analgesia was not employed, rather pre-emptive analgesic effect of gabapentin (plus dexamethasone) or pregabalin was studied on consumption of a single postoperative analgesic agent (ketorolac [38] or pethidine [39]. Both used placebo for usual care groups.
A multimodal approach has been recommended for perioperative pain management in major breast cancer surgery. A successful multimodal approach requires coordination between surgical, anaesthesia, and nursing staff throughout perioperative period. Recent recommendations [67] are to use antiepileptic medication (gabapentin or pregabalin), paracetamol, and regional nerve blocks (paravertebral blocks, PEC blocks, or thoracic epidural injection), wound infiltration with LA at the end, NSAIDs, and intermittent short-acting opioids. This regimen should be continued for up to 1 week after surgery. Other classes of medications can also be used such as, intravenous lignocaine, N-methyl-D-aspartate (NMDA) antagonists such as ketamine and magnesium, alpha-2-adrenergic antagonists clonidine and dexmedetomidine. Glucocorticoids such as dexamethasone have been used to minimize postoperative pain, nausea and vomiting.
PROSPECT recommendations for non-cosmetic major breast surgery [68] include paravertebral block, gabapentinoids, COX-2-selective inhibitors, paracetamol, IV dexamethasone, intercostal nerve block plus other regional techniques (TPVB), NSAIDs, strong opioids, (for high intensity pain) or weak opioids for moderate to low intensity pain, paracetamol alone or in combination with other non-opioid analgesics for low to moderate intensity pain. Majority of the RCTs [seven] employed thoracic paravertebral blocks, followed by PECS I and II block [four]. Though regional techniques were employed, there was a gap in comparison to the recent recommendations, such as preoperative use of antiepileptic medication, paracetamol and, intraoperative wound infiltration with LA, NSAIDs, and intermittent short-acting opioids. Usual care or control groups used different drugs or different concentrations of the drug for TPVB and PECS I and II blocks. In LMIC, incidence of breast cancer is rising and increasing number of patients are undergoing these procedures. Healthcare teams hence are required to develop and follow multimodal pain management protocols as per recent recommendations to provide quality care to their patients. Multimodal preventive analgesia regimen needs to be followed in patients scheduled for major breast cancer surgery.
Moderate to severe pain is not uncommon after orthopedic procedures, especially after joint replacement surgeries. If not adequately controlled, there is a high probability of developing persistent post-surgical pain. Two commonly performed procedures in the lower limb are total knee arthroplasty (TKA) and hip replacement surgery. In RCTs carried out in LMIC, the modalities used for TKA were local anaesthetic infiltration in joint space, lumbar epidural, combined spinal epidural, and lumbar plexus block. According to the PROSPECT recommendations [68] for TKA, peripheral neural block is strongly recommended for best post-operative pain management. Epidural block is only recommended for patients having increased risk of cardio-pulmonary complications and in those cases where general anaesthesia is contraindicated due to increased risk of morbidity; otherwise epidural is not recommended for post-operative analgesia after TKA. Intra-articular infiltration of local anaesthetics is also not recommended because of inconsistent evidence. Similarly ASA (American Society of Anesthesiologists) strongly recommends the use of peripheral nerve blocks, either continuous or single shot, after TKA and hip surgeries [69]. Hence in LMIC, the post-operative pain management practices for lower limb surgeries are not according to the evidence based recommended methods, which is probably due to lack of expertise in performing peripheral nerve blocks, lack of knowledge, or due to a large patient volume.
On the contrary, for upper limb and shoulder surgeries the studies done in LMIC have shown that peripheral nerve blocks were used for post-operative pain management. ASA also strongly recommends peripheral nerve blocks for upper extremities and shoulder surgery. However there is no recommendation by PROSPECT for upper limb surgeries as yet. Hence the pain management strategies for upper limb surgeries in LMIC seem to be consistent with the current practice of the developed countries.
Though the review shows a congruence of RCTs being carried out in the LMIC with internationally available recommendations and guidelines in majority of the instances, it is pertinent to realize that clinical practices on the ground may not reflect this. The findings of this review should be interpreted cautiously as majority of RCTs are small. This indeed is a limitation of the review. Placebo was used in four RCTs for the control groups, replacing study drug/intervention. Although there were other analgesia options in the multimodal regimen being used to treat pain, use of placebo is outdated and not encouraged for pain research.