Postoperative pain: management and innovation - Pathos

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Postoperative pain: management and innovation

Dolore postoperatorio: gestione e innovazione
Short review
Pathos 2022; 29, 1. Online 2022, May 30
Nicola Maratea
Responsabile UOSD
Coordinamento attività anestesiologiche
Ospedale di Policoro, ASM Matera

Despite the growing interest in the acute postoperative pain treatment and care, many steps need to be taken in both a technical and organizational sense to achieve optimal results. The most difficult problem to solve is the daily contrast between the clinical evidence of efficacy and the work differences in which every anesthetist finds himself operating. In our hospital, we have tried to reach a compromise between the adequate and updated use of technical and pharmacological resources and the organizational support of the individual healthcare realities. The basis of multimodal therapy is synergism, or mutual pharmacological enhancement, by associating sub-maximal doses of analgesic substances with different mechanisms of action to increase therapeutic power and reduce adverse effects.
Nonostante il crescente interesse per il trattamento e la cura del dolore acuto postoperatorio, molti passi devono essere compiuti in senso sia tecnico sia organizzativo per ottenere risultati ottimali. Il problema più difficile da risolvere è rappresentato dal contrasto quotidiano tra l'evidenza clinica di efficacia e le differenti realtà lavorative in cui ogni anestesista si trova a operare. Presso il nostro Ospedale, da tempo si è cercato di raggiungere un compromesso tra l'utilizzo adeguato e aggiornato delle risorse tecniche e farmacologiche e il supporto organizzativo delle singole realtà assistenziali. La base della terapia multimodale è il sinergismo, ovvero il mutuo potenziamento farmacologico, associando dosi sub-massimali di sostanze antalgiche con meccanismo di azione diverso per aumentare la potenza terapeutica e ridurre gli effetti avversi.
Key words
Postoperative pain, innovation, resources, technology, drugs
Parole chiave
Dolore postoperatorio, innovazione, risorse, tecnologia, farmaci

It was once believed that the surgical act, absolutely central and pre-eminent fact, involved pain as an inevitable consequence that, in a paternalistic conception of medicine, was considered an acceptable price by the patient for the therapeutic benefit that the intervention guaranteed, or should have guaranteed. The situation has gradually evolved for a number of reasons of a clinical, ethical and managerial nature.1
Postoperative pain is a classic acute pain; hyperalgesia and the intensification of over-sensitization to painful stimuli are the result of the lowering of the threshold of nociceptors, sensitized by the release of the mediators of inflammation as a result of trauma or tissue damage;a form of biological amplification of the painful stimulus.2
Pain is ethically unacceptable and it is recognised that adequate analgesia after surgery contributes significantly to the reduction of morbidity and postoperative mortality. Even today, postoperative pain is not adequately treated, constituting one of the main problems of the surgical patient.
It is acknowledged that the solution to the problem of inadequate treatment of postoperative pain lies not only in the development of new drugs or new techniques, but also and above all in the development of an organization to a better use of existing techniques. Despite the continuous flourishing of guidelines and protocols for the treatment of acute postoperative pain, it is increasingly evident how it is difficult to achieve satisfactory results, especially in the daily clinical environment. Several surveys conducted in recent years have shown how painful the postoperative experience is for most patients. Yet we know how important it can be to treat pain early in terms of short- and long-term outcomes.3-5

Intense perioperative pain causes pathophysiological effects that are mainly evident in three systems: cardiovascular, respiratory and immune. It should also be emphasized that the development of a failure of any organ, if not promptly corrected, predisposes to the deterioration of other systems, producing a very dangerous, often very difficult to overturn, picture of multi-organ failure, what the British call the "failure of several organs".
In recent years we have seen a significant increase in the treatment of acute pain. However, this is still the exception and not the rule: most patients suffering from diseases associated with intense pain still suffer untold torments. These sufferings are completely useless, since the current knowledge, drugs and technology at our disposal, if properly applied, allow patients to obtain an analgesia that allows a comfortable postoperative period even after highly invasive and traumatic interventions.
The main factors involved in causing postoperative pain, in its intensity, quality and duration, are:
1) Place, nature and duration of the assistance;
2) Type of incision and extent of intraoperative trauma;
3) Psychological and physiological disposition of the patient;
4) Psychological, physical and pharmacological preparation of the patient by each member of the surgical staff;
5) Development of serious complications related to the surgery;
6) Anesthetic treatment not only during, but also before and after surgery;
7) Especially the quality of postoperative treatment.
There is a well-known correlation between the frequency of pulmonary complications and the localization of pain. Upper chest or abdominal pain will prevent the patient from breathing easily and coughing.
However, postoperative pain is pain that is not only controllable but completely predictable and also almost totally preventable.
Postoperative analgesia is becoming increasingly important in patient management. Normally, antalgic treatment was practiced after the painful stimulus (for example surgery) had reached the nerve centers. More recently, preemptive analgesia before the start of surgery is recommended. The key concept of preemptive analgesia is that painful stimulation induces pain memory. Pain therapy is most effective if it is started before the tissue insult activates the peripheral nociceptors and activates the central sensitization.
Preemptive also requires behavioral intervention that can reduce stress and anxiety.6-8 The need to achieve rapid functional recovery of the surgical patient, through early mobilization and nutrition, has led to a reconsideration of the use of substances and to adopt therapeutic strategies that would allow, with equal effectiveness, to reduce consumption. The concept of multimodal analgesia was introduced more than 20 years ago and still represents the principle to which the main scientific societies and guidelines refer:  if there are no contraindications, non-opioid drugs are recommended at fixed times throughout the postoperative period. There is another important reason why these drugs are indispensable in the treatment of acute pain.
After a tissue injury, the production of inflammatory factors (PG) determines on the nociceptor a pronocicective action by lowering its threshold of stimulation. From the inflamed site, substances such as interleukins (IL1B) are also released, which by blood reach the CNS and are responsible for the overproduction of PGE2 centrally.
Central sensitization may persist long after trauma, as alterations in perception are maintained by bio-chemical-structural changes mediated by intracellular calcium or other "secondary messengers". Once started, the process of spinal sensitization is difficult to control. Hence operational strategies to control postoperative pain, such as spinal opiates and local anesthetics, are much more effective when applied before receptor activation. For this reason, loco-regional anesthesia, which induces the blocking of nociceptive transmission, together with the administration of opiates and prolonged for the first postoperative period, is the best method of prevention of "spinal sensitization". Recent experiences on pain control have shown the effectiveness of neural block pain transmission, carried out before the beginning of surgical trauma.9
Important studies (10) have shown the importance that central inhibition plays in the modulation of nociception. There are therefore two types of signals that start from damaged and inflamed tissues and arrive at the central nervous system: the first is mediated by the electrical activity of the sensitized nerve endings of the injured area wich provide us with information on the site, on onset, duration on type of damage. This first signal is sensitive to peripheral COX2 inhibitors and nerve block with local anesthetics. The second signal is instead of humoral type and leads to the induction of COX2 throughout the CNS, is sensitive to COX inhibitors that are able to cross the blood-brain barrier. Untreated or inadequately controlled pain is the most common medical problem; it tends to worsen as the population ages and increases the risk of algogenic pathologies and disorders. It is helpful to administer drugs early, when tissue damage is expected and before the release of inflammatory mediators, such as in the preoperative period.

Already Crile11 had noticed the protective effect of adequate premedication, combined with a deep regional block, combined with a general "light" anesthesia. These data have been confirmed by experimental research with which the consumption of analgesics in the postoperative period in patients undergoing loco-anesthesia has been reduced.12 The administration in epidural or CSE of local and opioid anaesthetics provides an analgesia higher than that obtained with both intravenous PCA and intramuscular opiates. In fact, in epidural opiates in combination with low doses of local anesthetic are able to prevent the perception of pain. This technique does not achieve a complete abolition of responses to stress, which is not always necessary, but a condition of "absence of pain" (pain free state) is achieved with an effective modulation of the sympathetic-responseadrenergic, and a reduction in cortisol incretion and a consequent improvement in nitrogen balance. These results largely justify the increased invasiveness of epidural analgesia, compared to traditional methods. The intravenous PCA, even if able to supply an effective and constant analgesia, does not prevent the perception of the pain that even if of modest entity, and however able to start the humoral and neural response to the stress.13
The use of peripheral blocking techniques in the treatment of postoperative pain is rapidly expanding and reflects the tendency of modern anesthesiology to ensure:
1) Analgesia targeted to the real needs of the patient and the surgeon
2) Selectivity of action
3) Limited risks and virtual absence of serious or unpleasant side effects.
However, such methods require a wide range of anatomical knowledge and experience. Their main field of application is without a doubt orthopedic surgery, where the possibilities are very wide, but also in general, vascular, plastic, ENT, and outpatient surgery generally there are opportunities to appreciate its effectiveness and versatility. The most evident results are in patients suffering from heart or lung disease, which may benefit from reduced consumption of myocardial oxygen, improvement of respiratory function and early mobilization with also reduction of thromboembolic risk.14
Clinical cases
After years of experience with Combined Spinal and Epidural (CSE) method, in May 2020 we decided to undertake a review of the protocol used over the years in retrospect. In our Hospital too, CSE has become one of the most widespread methods for the control of postoperative pain with a series of more than 600 patients treated over the years. Postoperative pain relief, including VAS detection, was provided in all patients for the first 24 hours. Continuous infusion with electronic pump or elastomer at 6-7 ml/h of levobupivacaine at 0.625%, hydrochloric morphine 2-3 mg, octreotide 0.05 mg  or clonidine 0.05 mg in the 24-hour observation period. The removal of the epidural catheter occurred at a variable distance from the surgery, between 24 and 36 hours.15-20

Advantage of CSE
1) Ability to manage postoperative analgesia
2) Better patient satisfaction
3) Reduction of anxiety
4) Reduction of total drug doses
5) Lower incidence of side effects
6) Reduction of stay time
The ideal analgesic treatment consists of a mixture of drugs (balanced analgesia) which act at different levels to be able to abolish the various components of the painful stimulus and thus suppress the responses associated with them. A multidisciplinary and multi-professional approach is considered as a fundamental element for future strategies on postoperative care. Epidural analgesia represents an advance of PCA, as it provides a more effective analgesia with fewer side effects. Thus, epidural analgesia and CSE offers the potential for a better outcome without increased risk. The local anesthetics of choice for postoperative analgesia are levobupivacaine and ropivacaine for the long duration of action. Associated with opioids at low concentrations, they do not involve hemodynamic instability or motor block (0.125% -0.0625%)
Ropivacaine gives a number of important advantages:
1) Favorable balance between sensory and motor block
2) Reduced cardiotoxicity
3) Pharmacokinetics known for infusions lasting up to 72 hours
Ropivacaine, due to its lower lipid solubility, offers a more favorable balance between sensory and motor block, when compared with levobupivacaine.

CSE is recognized as the most effective technique in the postoperative pain control.
This can best be achieved by developing a more integrated multidisciplinary and multimodal approach to patient management. This approach implies close relationships between surgeons, anesthesiologists, nurses, physiotherapists and allows for early patient re-installation and mobilization.21-23
It is now recognized that an adequate treatment of postoperative pain significantly improves the outcome of patients undergoing major surgery, demonstrating a lower incidence of postoperative complications, of hospitalization days with a consequent reduction in costs.
The postoperative period should be considered as a "true disease" with a multifactorial etiology and with a common denominator: the pain symptom. The "postoperative pain syndrome", again, should not be evaluated only as strictly welfare, but also social, if we consider the increase in management costs, a direct consequence of the delayed discharge of patients in whom it is not properly treated.

Conflict of interest
The author declares that the article is not sponsored and that it was written in the absence of conflicts of interest.
30th May 2022
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