1. Context
Against the backdrop of more than 320 million surgical procedures per year worldwide (1), perioperative pain control should be a high-priority issue within health care providers. However, in contrast to the belief of many therapists, postoperative pain is still markedly ‘undermanaged’ (2, 3). The rationale of this review was to increase therapists’, particularly anesthesiologists’ and surgeons’, consciousness of the ongoing unfortunate situation of post-surgical patients with moderate to severe/unbearable pain, including concrete proposals for solution. Physicians should be repeatedly reminded of the famous saying of Galen of Pergamon, “divinum est sedare dolorem” (it is divine to ease pain).
2. Evidence Acquisition
The aim of this review was to discuss reasons and potential solutions for a condition, which is highly unpleasant for patients and unflattering for therapists. The focus was on surgical procedures creating severe postoperative pain, with the emphasis on the outstanding potential of continuous regional blocks with catheters.
3. Results
The subject of whether the method of postoperative pain control influences outcome parameters, such as major complications or length of hospital stay, is an ongoing debate (6). However, the discussion frequently misses patients’ central concern: their suffering and discomfort. As matters now stand, the 2016 statement of Rawal remains unchanged, “Postoperative pain has been poorly managed for decades. Recent surveys from USA and Europe do not show any major improvement” (7).
3.1. Current Situation of Postoperative Pain Control
In his 2010 review, Sinatra (8) complained about the unsatisfactory situation of patients with severe postoperative pain, and concerns are still shared by others (7, 9, 10). The team of Gan published several surveys describing the situation of postoperative patients in the United States. In the years 2003, 2014, and 2017, inadequately treated postoperative pain was almost similar with an incidence of 86%, 75% (74% after discharge), and > 80%, respectively (3, 11, 12). This indicates that during a period of 14 years, postoperative pain control did not change for the better.
Several guidelines with questionable effect have been implemented. Meissner et al. in their 2018 multinational consensus report (13) noted, “despite the introduction of evidence-based recommendations for postoperative pain management, the consensus is that pain control remains suboptimal”, a statement we perceive as euphemistic.
3.2. Alternatives for Sufficient Postoperative Pain Therapy
For treating severe pain, opiates are effective, although they have considerable adverse effects, such as sedation, post-operative nausea and vomiting (PONV), urinary retention, pruritus, and constipation (14, 15). However, regional analgesia (RA) using mainly local anesthetics lacks these side effects. In their current review, i.e. ‘state of the art opioid-sparing strategies for post-operative pain in adult surgical patients’, Gabriel and co-workers emphasized both the excellent analgesic potential of RA and its ‘opiate-sparing’ effects (16).
Table 1 shows observational data of a large German hospital (17, 18) with a variety of regional catheters, demonstrating that the majority of relevant postoperative pain conditions are treatable in this way.
Table 1.Regional Catheters for Perioperative Pain Control in Elective Surgical Patients. Publication Granted by the Authors (17)
| Procedure | Specifics | Indication | Schedule (Planned) | Done (%) |
|---|---|---|---|---|
| Epidural catheter | Lumbar | Delivery (obstetrics) | 70 % | 45 |
| Artery occlusive disease of the lower limb | ALL | 96 | ||
| Thoracic | Major abdominal and thoracic surgery | ALL | 97.4 | |
| Femoral catheter | Major knee surgery | ALL | 100 | |
| Sciatic dorsal catheter | With FC only | Major knee surgery | 10% | 98 |
| Sciatic ventral single injection | With FC only | Major knee surgery | 90% | 100 |
| Brachial catheter | Interscalene approach | Major shoulder surgery | ALL | 99.3 |
Abbreviation: FC, femoral catheter
It is difficult to judge the efficacy of individual pain treatment strategies and compare them with others. This is mainly due to the lack of crucial information, such as techniques of catheter insertion and postoperative maintenance, qualification and responsibilities of respective therapists, and if mandatory standards have been applied. Although from years back, the 2012 statement of Hermanides et al. (19) regarding neuraxial analgesia is still highly relevant, “estimates of the incidence of failed epidurals are hampered by the lack of uniform outcome measures”. As a consequence, published success/failure rates have to be considered with the utmost caution. The issue is well exemplified by the 2018 Cochrane review of Salicath et al. (20), comparing epidural analgesia (EDA) with patient-controlled intravenous analgesia after major abdominal surgery in adults. As was concluded, “any improvement needs to be interpreted with the understanding that the use of EDA is also associated with an increased chance of failure to successfully institute analgesia, and an increased likelihood of episodes of hypotension requiring intervention and pruritus”. However, according to our understanding, neither failure rate nor postoperative pruritus was attributable to EDA itself. The EDA efficiency depends on therapists’ skill, as well as positioning and fixation of the catheter, whereas pruritus is a well-known effect of epidural opiates. With adequate organization, hypotensive episodes are not also considered relevant clinical problems.
In view of the fact that there is no coherent, generally accepted definition of failure regarding RA, we agree with the unambiguous criteria for ‘effective’ catheter-related analgesia of von Bormann et al. (17):
1. No need for routinely administered additional systemic analgesics;
2. No relevant side effects and no complications;
3. VAS score (0 - 10) continuously ≤ 3 during movement; patients are satisfied;
4. Length of the in situ period of the respective catheter as scheduled.
3.3. Specific Procedures-Peripheral Catheters
3.3.1. Femoral and Sciatic Block
Major knee surgeries, such as total knee arthroplasty, cause extreme pain, normally lasting 2 to 3 postoperative days. Ongoing pain control is crucial to enable mobilization starting immediately after surgery. The 2014 Cochrane review by Chan et al. (21) suggested superior effects of femoral catheter for pain control after total knee replacement, especially when combined with sciatic block or periarticular infiltration.
Femoral catheter insertion is simple; therapists can orientate themselves to clear landmarks, particularly the femoral artery. Ultrasound is not necessary and stimulation of the needle is adequate. However, the method has been increasingly challenged and adductor canal block (ACB) is becoming an attractive alternative.
3.3.1.1. Motoric Function and Adductor Canal Block
There is concern among surgeons and physiotherapists that continuous femoral nerve block (FNB) may hamper motoric function, thereby leading to delayed ambulation and increasing risk of falls (22). As a consequence, ACB has been promoted in order to provide adequate analgesia with less quadriceps weakness compared to femoral block (23, 24). However, Schwenk and Gandhi (25) focused on conclusions drawn from dynamometer data and emphasized that differences in motoric function between ACB and FNB were significant only during the first 8 postoperative hours, whereas fall accidents mostly occurred on the second postoperative day. Memtsoudis et al. (26) selected 191,570 total knee arthroplasty patients from the national (US) Premier Perspective Database. The overall inpatient fall (IF)-incidence was 1.6% without any association between IF and peripheral nerve blocks. To evaluate the assumption that ACB is only an indirect femoral block (27), Chuan et al. (28) conducted a multinational, multicenter, double-blinded randomized trial. They found no differences in immediate postoperative functional mobility, analgesia, and opioid consumption provided by FNB and ACB catheters for total knee arthroplasty surgery.
Currently, experts’ opinion regarding FNB and ACB appears to be undecided, with the use of the respective technique obviously based on individual therapists’ preferences.
3.3.1.2. Efficacy and Complications
Accurate and systematically collected failure rates of FNB or ACB have not yet been investigated. Popping et al. (29) in their observational study included 1,374 patients with femoral/sciatic block. They reported a failure rate of 3.96% and moderate infections without late sequelae in 35 patients (2.4%).
However, there have been reports about some few serious complications including compartment syndrome, periprosthetic fracture, and vascular injury (30). Widmer et al. (31) investigated 1,802 patients with femoral block, reporting an incidence of 1.94% sensory abnormalities in the distribution of the femoral nerve without lasting damage.
3.3.2. Brachial Block with Interscalene Catheter
The shoulder is another anatomic area with high sensitivity to pain (32). Common surgical procedures such as endoscopic removal of exostosis require passive movement of the joint immediately after surgery to avoid ‘frozen shoulder’. The shoulder has to be pain-free for this maneuver, which can be best achieved with a brachial plexus block via interscalene catheter. In cases with intermittent immobilization, bolus applications before physiotherapy may be preferable to continuous infusion.
3.3.2.1. Efficacy and Complications
Ullah et al. in their Cochrane review found better pain relief for continuous interscalene brachial block compared to parenteral analgesia (33). Failure rates can be low (0.4%) (34) or extremely high (18.8%) (35). Potential complications after interscalene catheter insertion are hoarseness, neurologic sequelae, dyspnea, and nerve injury; the reported incidence ranges from 0.8% long-term neurologic deficits to 31% hoarseness (36, 37). Inserting a sufficiently working interscalene pain catheter is a sophisticated technique requiring adequate training (32).
3.3.3. Peripheral Nerve Blocks for Postoperative Analgesia: Type of Application
Ilfeld and Gabriel (38) recently raised the issue of type of application for perineural catheters, asking “should we take the ‘continuous’ out of ‘continuous peripheral nerve blocks’?”, a concern that may lead to an ongoing debate regarding resources and efforts for RA. Organizing and monitoring bolus applications is, without question, less effortful compared to continuous application.
3.3.4. Neuraxial Blocks-Paravertebral Catheters
One of the first publications on paravertebral block (PVB) including a 2 year follow-up period was the 1998 report of Coveney and colleagues (39) in patients with breast cancer surgery. Since then, PVB has been used for pain control in different surgical settings, mainly after thoracic surgery (40). Norum and Breivik (41) do not consider PVB equivalent to EDA in thoracic surgery. Among others, they emphasize that optimally conducted EDA has not yet been compared with PVB.
3.3.4.1. Efficacy and Complications
The incidence of complications after paravertebral puncture may be low. However, the severity of events such as pleural or vascular puncture, hypotension, bilateral epidural, and intrathecal spread is a matter of concern. Naja and Lonnqvist (42) studied the outcome characteristics of thoracic and lumbar PVBs in 620 adults. The general failure rate was 6.1%; most relevant complications were vascular and pleural puncture, epidural or intrathecal spread, and pneumothorax. Moreover, the use of a bilateral paravertebral technique resulted in doubling of vascular puncture (9% vs. 5%) and an eight-fold increase in pleural puncture and pneumothorax. Sufficient placement of paravertebral catheters requires profound knowledge of anatomy, skill in puncturing the paravertebral space, and experience in applying ultrasound. In their randomized study, Sundarathiti and co-authors (43) performed paravertebral catheters as stand-alone anesthesia in major breast surgery. The catheters, although 100% sufficient to perform surgery including extensive axillary lymph node removal, were not left in situ due to organizational issues. Nevertheless, the study showed that catheters under ultrasound guidance could be advanced 8 cm deep into the paravertebral space without complications, relevant technical difficulties, or kinking, confirming the potential of PVC for postoperative pain control.
3.3.5. Neuraxial Blocks-Epidural Catheters
Based on a large body of evidence, EDA with thoracic approach remains the first-line therapy to control pain after major abdominal and thoracic surgery (44-46), whereas lumbar catheters are suitable in obstetrics and for patients with artery occlusive disease of the lower limb. Concerns about outcome deterioration due to delayed bowel function return, hypotension, and urinary retention caused by EDA are not substantiated; EDA does not lead to an increased risk of any major complications or relevant side effects (47, 48).
3.3.5.1. Efficacy
Majority of studies, some of them with large sample sizes, have demonstrated significant benefits of EDA for patients’ comfort and outcomes (17, 44, 49, 50), with the study of Monaco and co-workers (48) being an example. They investigated 459 consecutive patients with open thoraco-abdominal aortic aneurysm repair, with 409 (89%) patients receiving thoracic EDA (TEA). The patients with TEA, when compared to the other patients, experienced significantly less post-operative pain, as well as less complications, such as acute kidney injury, atrial fibrillation, and acute myocardial infarction. Moreover, there was no epidural hematoma/infection or paraplegia. The results remained statistically significant, even after propensity matching (43 vs. 43 patients). In our opinion, EDA is still the gold standard for controlling intense abdominal and thoracic pain.
3.3.5.2. Failure Rate
As a consequence of unclear or different criteria to assess the effectiveness of EDA, the reported failure rates vary over a wide range (Table 2). Primary reasons for failure are dislodgement/migration of the catheter, which was conclusively demonstrated by Motamed et al. (51) using postoperative computer tomography. Other relevant causes for insufficient therapeutic effects include delayed injections (19) and under-dosing of respective agents, as demonstrated by Panousis et al. (52) comparing intraoperative ropivacaine 0.2% and 0.5% with placebo. Once again, we emphasize that the dose of local anesthetics determines their effects, whereas concentration and volume affect onset of action and spread, respectively (53). To avoid relevant motoric and sympatholytic effects, the smallest possible volume with adequate concentration should be applied. Therefore, the tip of the catheter has to be in the center of pain perception, which is for major abdominal and thoracic surgery between Th 6 and Th 10. An interesting approach to reduce failure rates has been reported by Larsson and Gordh (54). They tested the effectivity of epidural catheters directly after insertion and before surgery and managed to reduce failure rates significantly. Delays did not exceed 10 - 15 minutes (Table 2). Failure of EDA catheters can be significantly reduced by improving perioperative organization, as it has been nicely demonstrated by Gleicher and co-workers (55). They decreased the failure rate of thoracic epidural catheters (112 vs. 142 patients) from 16.0% to 5.6% after implementing a separate block room. We also need to point out that a separate block room also reduces the delay of operating theatre turnover, as regional catheter insertions, particularly epidurals, can be performed simultaneously to a running OR. Our own data indicate a time saving of 12 - 25 minutes per major procedure. Installing and operating a block room should be easily manageable for large departments. However, for smaller units, additional efforts and extra holding of specialized personnel may be a matter of concern. Finally, regardless of organizational issues, our own experiences indicate that proper fixing of catheters, such as epidural or central venous lines, is paramount to ensure that catheters remain in position and also to avoid catheter-related infections.
Table 2.Published Failure Rates of Epidural Pain-Catheters
| Author, Year of Publication | Surgical Approach (Number of Patients) | C-Position (Failure Rate) | Reasons for Failure/Success |
|---|---|---|---|
| High Failure Rate | |||
| Burstal, 1994 (56) | Abdominal (1,062) | Lumbar, thoracic (23%) | Premature removal, no analgesic effect |
| Ready, 1999 (57) | Abdominal, thoracic (2,140) | Thoracic (32%); Lumbar (27%) | Migration, ineffective |
| McLeod, 2001 (58) | Upper abdominal, thoracic (640) | Thoracic (13%) | Dislodgement, malposition, occlusion |
| Motamed, 2006 (51) | Upper abdominal (125) | Thoracic (24.8%) | Dislodgement, verified by computer tomogram |
| Pratt, 2008 (59) | Pancreaticoduodenectomy (158) | Thoracic (31%) | Dislodgement, early abortion |
| Königsrainer, 2009 (60) | Thoraco-abdominal (300) | Thoracic (41.4%) | Dislodgement |
| Sakowska, 2009 (61) | Pancreaticoduodenectomy (51) | Thoracic (25%) | Unplanned removal |
| Choi, 2010 (62) | Pancreaticoduodenectomy (18) | Thoracic (36%) | Unplanned removal |
| von Bormann, 2013 (17) [1989-1992]a | Upper abdominal, thoracic (1,880); Lower abdominal/limb, thigh amputation (620) | Thoracic (19.3%); Lumbar (16.9%) | Catheter migration, malposition, early abortion |
| Patel, 2014 (63) | Pancreaticoduodenectomy (73) | Thoracic (42.5%) | No effect (site of catheter insertion?) |
| Wranicz, 2014 (64) | Upper abdominal, thoracic (317) | Thoracic (34.4 - 41%) | Dislodgement, malposition, occlusion |
| Wongyingsinn, 2016 (65) | Upper abdominal, thoracic (364) | Lumbar/Thoracic (48.6%) | Dislodgement, ineffective, wrong anatomic position |
| Gleicher, 2017 (55) | Upper abdominal (112) | Thoracic (16%) | Organizational issues |
| Low Failure Rate | |||
| Pan, 2004 (66) | Obstetrics (19,259) | Lumbar (1.2%) | Immediate re-insertion in case of inefficacy |
| Popping, 2008 (29) [1998 - 2006]a | Thoracic and major abdominal (10,198) | Thoracic (7%) | Standards |
| Larsson, 2010 (54) | Upper abdominal surgery (100) | Thoracic (2%) | Testing and re-inserting the catheter before surgery |
| von Bormann, 2013 (17) [1993 - 2010]a | Upper abdominal and thoracic (8,828), lower abdominal/limb, thigh amputation (2,755) | Thoracic (3.7%); Lumbar (3.1%) | Mandatory standards, catheter sewing, re-insertion, block room |
| Gleicher, 2017 (55) | Upper abdominal (142) | Thoracic (5.6%) | Block room |
aInvestigation period.
3.3.5.3. Complications
Typical adverse side effects of EDA are hypotension, urine retention, and pruritus, the latter mainly caused by neuraxial opiates (15). With a thoracic catheter in the center of pain perception, deterioration of motoric function or bowel function is not an issue (17, 44, 67). Complications after epidural puncture are rare but may have dramatic effects including paraplegia (68). However, the currently available literature suggests that the benefits of EDA outweigh its risks and side effects (44, 46, 49, 50, 69, 70). Thoracic epidurals are inserted in close vicinity to the spinal cord; the procedure has to be performed by experienced professionals (71).
3.4. Synopsis
Regional analgesia with catheters is highly effective when performed properly. It is not in any competition with alternative methods. However, new methods such as modified local infiltration techniques and percutaneous nerve stimulation (72, 73) have to be proven superior before replacing established procedures.
3.4.1. Agents
In contrast to many others, we do not recommend adding adrenaline to local anesthetics, although there are no sufficient data to support this strategy. We are, however, in agreement with Wiles and Nathanson (74), challenging the assumed benefits. Mauch et al. (75) observed t-wave, blood pressure, and heart rate alterations after adrenaline-containing LA, but could not distinguish whether the catheter was actually intravascular or whether the observed effect was the result of resorption. Nevertheless, we have to admit that the majority of anesthesiologists still oppose our strategy and hence the discussion is still open.
3.4.2. Organization
In cases of inadequate effect, catheters should be re-inserted as suggested by Pan et al. (66). Patients in the general ward should be regularly visited twice a day by members of the pain service, and in cases of particular need. A 24-hour emergency service must be ensured. Moreover, a separate block room should be implemented wherever possible.
3.4.3. Standard Operating Procedures (SOP), Patients with Anticoagulants
Standardizing procedures is key to guarantee patients’ safety and efficacy of procedures. SOPs should be mandatory; they are not ordered ‘top-down’ but have to be developed by the people involved, such as anesthesiologists, surgeons, oncologists, pharmacists, and purchase department, with the general manager or clinic director finally bringing it into effect.
As an example for the necessity of standards as an essential safety measure, Table 3 shows our own SOP for patients with compromised coagulation, including the most common anticoagulants. However, utmost caution has to be exercised for all regional catheter insertions. We strongly recommend that every facility should create and update its own SOPs adapted to the situation of the respective department/hospital.
Table 3.SOP Example Regarding Puncture/Catheter Application Near the Spinal Cord in Patients with Compromised Coagulation, Focusing on Time Intervals Prior To Puncture and Catheter Insertion or Removal
| Puncture | Removal | Reliable Biochemical Control Parameters | |
|---|---|---|---|
| Unfractioned Heparin, Prophylaxis < 15.000 U/day | 4 h | 1 h | If therapy > 5 days: Thrombocyte count |
| Unfractioned Heparin: High dose therapy | 4 - 6 h | 1 h | PTT, (ACT), thrombocyte count |
| Low molecular Heparin: Prophylaxis | 12 h | 2 - 4 h | > 5 days: Thrombocytes |
| Low molecular Heparin: Therapy | 24 h | 2 - 4 h | Thrombocytes (anti Xa) |
| Fondaparinux (Arixtra®) (prophylaxis < 2.5 mg/die) | 36 - 42 h | 6 - 12 h | (anti Xa) |
| Vitamin-K-Antagonist, such as Warfarin, Cumarin | PT > 70% | PT > 50% | PT |
| Hirudin (Lepirudin, Desirudin) | 8 - 10 h | 2 - 4 h | aPTT, ECT |
| Argatroban (Argatra®) | 4 h | 2 h | aPTT, ECT, ACT |
| Acetylsalicylacid (Aspirin) 100 mg (ASS 100®) | None | None | PFA (Platelet function); CAVE: Combination with Heparin or antirheumatic agents |
| Clopidogrel | 7 days | 7 days | There are none |
| Ticlopidin (Tyclid®) | 10 days | 10 days | There are none |
| NSAR | None | None | There are none |
3.4.4. Patients with Immunosuppression
Deterioration of the immunologic system is not per se a contraindication against any kind of pain catheters, assuming that the indication (pain status) is solid and the procedure is performed as described: sterile and atraumatic.
3.4.5. Expenses/Manpower
Expenses for RA are high, mainly due to safety and organizational measures, leading to extensive use of specialized medical personnel. The costs for RA exceeds those for patient controlled analgesia significantly, whereas systemic treatment (injection on demand) is by far the cheapest, yet the least effective alternative (Table 4). The delay of turnover time of operating rooms (OR) can indeed be a significant cost factor. However, it is also the source of conflicts between anesthesiologists and surgeons, a problem best managed with a ‘block room’ that serves several ORs.
Table 4.Expenses for 2-Day Alternative Pain Treatment
Abbreviations: MO, morphine; PCA, patient controlled analgesia
aOwn experience and educated guesses in more than 1,000 applications per year (averaging calculation)
We believe that costs as a limiting factor may be often a ‘lame excuse’, especially in large departments where manpower and expenses can easily be acquired by organizational measures, such as optimizing the schedule of operating rooms.
3.4.6. Lacking Expertise
The application of pain catheters requires skill, confidence and expertise, and is only acquirable for the novice by adequate training including multiple applications under supervision. Failure rates are obviously dependent on permanency of anesthetic staff as it has been emphasized by Heinink et al. (77).
3.4.7. Limitations
Every narrative review includes the risk of bias. We inserted a balanced number of pro and con literature referring to every discussed issue. In addition, the authors possess above average knowledge and experience in invasive pain treatment.
4. Conclusions
The following recommendations can only work in a well-organized and well-equipped facility with sufficient resources and uncompromised cooperation.
1. Postoperative pain therapy is not a ‘sideline’. Regional catheters should be offered whenever indicated, given that adequate expertise and manpower exist.
2. Patient information: Complete clarification about side effects of the respective method and its potential complications including bleeding, anaphylaxis, or nerve injury is paramount. Patients should be informed as soon as possible, ideally during the first contact with the treating department, and after the decision for the respective surgical procedure. In patients with epidural catheter, the rare possibility of injury, infection, or bleeding of the spinal cord and its consequences (paraplegia) must be explicitly mentioned. Patients must be aware of the need to notify medical staff immediately about back pain, strong headaches, or unexpected numbness. Patients should also be informed about the possibility of insufficient or fading analgesic effects.
3. Catheters should remain in ‘one hand’ during the entire treatment period.
4. Applying catheters in the intensive care unit or the operating room does not require sterile gowns as long as the procedure is performed under strict aseptic and atraumatic conditions.
5. Mixing epinephrine with local anesthetics is common, and most therapists do it. However, we oppose the trend and do not recommend it, as we are reluctant to mix highly active drugs when scientific evidence lacks for its benefits.
6. For epidural catheters, anatomic position and adequate fixation are essential. We strongly recommend suturing, which requires a wire armored catheter.
7. Pain catheters should be activated after insertion, usually before skin incision.
8. A working pain catheter in adequate position does not require the routine application of additional systemic analgesics.
9. As for all invasive procedures, the application of regional/neuraxial pain catheters has to follow established standards, ideally implemented in the form of mandatory written SOP.
A great number of patients are still suffering from moderate to severe pain, or even worst pain, after surgery. The consequent application of regional pain catheters can help to effectively counteract this problem.
