Opioids have long been the go-to when prescribing analgesia for postoperative pain. However, as we have discussed in previous articles within this column, there is growing concern about how many people prescribed opioids postoperatively become addicted to their pain relief (Mendes, 2020). There is therefore a push at present to find other options in pain management, and to manage the dosing of opioids with awareness in terms of both not giving more than required and for as minimal a time as possible in the interests of the patient, while also of course ensuring it is enough to provide therapeutic benefit.
Glare et al (2019) note that inappropriate opioid prescribing after surgery, particularly following discharge, is a major contributing factor to rising deaths in the United States from prescription opioids. Chronic post-surgical pain occurs in about 10% of patients who have undergone surgery, typically beginning as acute postoperative pain that is difficult to manage, and soon transitions into a persistent pain condition with neuropathic features unresponsive to opioids (Glare et al, 2019).
Therapeutic suggestions
A recent study published in the British Medical Journal investigated the use of therapeutic suggestions played to patients through earphones during general anaesthesia while undergoing surgery, and their effect on postoperative pain and related opioid use. The research was a blinded randomised controlled study, that took place across five tertiary care hospitals in Germany (Nowak et al, 2020).
Consecutively from January to December 2018, Nowak et al (2020) recruited 385 patients who were to undergo surgery for 1-3 hours under general anaesthesia. There were 191 patients in the intervention group and 194 in the control group. The intervention developed by the researchers consisted of an audiotape of background music and positive suggestions based on hypnotherapeutic principles, being played repeatedly for 20 minutes followed by 10 minutes of silence to patients through earphones during general anaesthesia. Patients in the control group were assigned to a blank tape.
The main outcome was classified as a dose of opioid administered by patient-controlled analgesia or nurse-controlled analgesia within the first 24 hours following the surgery, based on regular evaluation of pain intensity on a numerical rating scale (range 0-10, with higher scores representing more severe pain).
Impact on pain
Interestingly, when the two groups were compared, it was found that the intervention group required a significantly lower opioid dose than the control group within 24 hours after surgery, with an average 4 mg morphine equivalents versus 5.3 mg for the control group, and an effect size of 0.36. The number of patients who required opioids postoperatively was significantly reduced in the intervention group also, whereby 121 of 191 (63%) patients in the intervention group compared with 155 of 194 (80%) in the control group, required the analgesia. Pain scores were found to be consistently and significantly lower in the intervention group within 24 hours of surgery completion, with an average reduction of 25%, and no adverse events were reported (Nowak et al, 2020).
Power of subconscious
Nowak et al (2020) concluded that therapeutic suggestions played via earphones during general anaesthesia could provide a safe, feasible, inexpensive, and non-drug technique to reduce postoperative pain and opioid use, and has the potential for more general use. Based on this finding of intraoperative perception by a significant number of patients, the researchers suggested that surgeons and anaesthetists should be careful about background noise and conversations during surgery. It is fascinating that a patient appears to be able to perceive and understand, perhaps on a subconscious level, sounds and speech while under general anaesthesia, and as a result be influenced in the choices they then decide to make.
Opioid use
The researchers explained that their study found a statistically significant reduction in use of postoperative opioids in patients who received therapeutic suggestions by audiotape during surgery, which comprised background music and mindful text. Furthermore, the number of patients who requested and received opioids was significantly lower following this intervention. The authors noted that any report of an effect on reducing medication requirement needs information that distinguishes a significant portion of patients have had a reduced need for the medication following the intervention. They also highlighted that the phenomenon of ‘intraoperative awareness’, the common explanation for intraoperative perception and the reaction of only a small number of patients, cannot account fully for the observed portion of affected patients, which involved a 26% higher abstinence from opioids.
Opioid consumption is one of the most appropriate and widely established measures to evaluate postoperative pain, especially when it is standardised and regulated such as in patient-controlled analgesia (to a numerical pain rating scale score 3). What is missing however is that pain intensity should also be considered as the two variables, pain and analgesia, are interdependent and inseparably connected. Further to this, pain scoring in the study by Nowak et al (2020) was part of a defined opioid treatment. Starting at admission and then in the post-anaesthesia care unit 24 hours after surgery, postoperative pain was observed to be significantly lower in the intervention group. In order to interpret the observed relatively high pain scores, it is important to take into account that the pain score and dosage of opioids were not matched. For example, the regular evaluation of pain could have taken place immediately before, immediately after, or at some time after the dose of the opioid.
Nowak et al (2020) also explained that their review of the literature found that particular words may also be processed by patients to their disadvantage—previous studies found that words such as ‘pain’ may in fact increase or even induce pain. Therefore, the researchers avoided negative words and negations in their text, and used connotations such as ‘increased comfort’ instead of ‘no pain,’ and with suggestions for regulation and reframing. Moreover, support, care, self-healing power, and meaning were communicated within the audios to the patients. Remarkably, they found analgesic effects without addressing the topics ‘pain’ or ‘analgesia.’ The tested suggestions were found to be associated with the general therapeutic goal of keeping the postoperative pain score under 3, with a number needed to treat pain being 6, to avoid postoperative opioids.
Strengths and limitations
As is the case with any research, the study was not without its limitations. The positive aspect of the study is that the fact the authors found a stronger effect of therapeutic suggestions during surgery than in previous studies may relate to their study design, with the analgesic requirement based on a NRS score for pain rather than the arbitrary administration of analgesia. Generally, with a liberal pain management and high opioid dosage, pain levels will be low and differ little between study groups. Conversely, restricted analgesia would lead to higher pain scores with high discriminatory power. The induced changes in pain and requests for opioids indicate a well-designed strategy for analgesic treatment and consideration of pain levels and opioid consumption (Nowak et al 2020).
The notably pronounced effects found in their study may also be associated with the highly developed text the authors chose for the audiotape. In this text, negative expressions such as ‘feel no pain’ or ‘absence of nausea’ were replaced by positive ones such as ‘increased comfort’, and the fundamental structure of the text for the therapeutic communication was based on themes derived from basic psychological needs and positive suggestions set against traumatic stressors. For example, the topics included by the authors were: support, contact, comfort, control, information, instructions, respect, safety, confidence, and healing. The hypnotic interventions included dissociation to a safe place of wellbeing, the reframing of disturbing sensations and noises, reinforcement of self-confidence, affirmation, and indirect suggestions (eg ‘He looks like he is really doing well’ in the third person, rather than a direct ‘You will be doing great’ (Nowak et al, 2020). However, studies of this kind for comparison unfortunately were very small and written up almost 20 years ago. Considerable changes and developments in anaesthesia and pain management have occurred throughout this time so comparison with such studies was difficult in terms of reliability.
A limitation of the study however is that the contribution of factors other than the therapeutic suggestions remains unclear. The authors explain for example that positive effects can be expected from the background music. Several beneficial effects have been described for perioperative music, among others, on postoperative pain and analgesia, they note. Despite this, most work on music used in a medical setting has been done on conscious patients before, during, or after surgery, and some meta-analyses have concluded that the effect of music is lower when given during general anaesthesia. Nowak et al (2020) also explain that an earlier randomised controlled trial on music given under controlled general anaesthesia found no effect on postoperative neurohormonal stress response and opioid dosage (Migneault et al, 2004).
The use of two methods for administering postoperative opioids, involving either patient-controlled analgesia or nurse-controlled analgesia, may also be considered a limitation. There were also limitations in the overall invasiveness, extent, and duration of the surgeries in this study. Therefore, to enable the results to be transferable to more invasive operations, such as cardiac surgery and other procedures with indication for postoperative intensive care, further research would be required.
The significant observed effect of the tested non-drug intervention not only reached statistical significance but is also of clinical interest. Validation using further and larger studies could lead to a call for a more general use of ‘therapeutic suggestions’ in surgical patients. The efficacy of intraoperative therapeutic suggestions shown by this study, combined with the low effort and costs necessary for implementation and with no side effects observed or expected, makes it difficult to argue against using this simple method for the reduction of postoperative pain and opioid use.