Massage therapy, considered a physical modality [9], was the most discussed nonpharmacological therapy for pain relief in the postoperative period of cardiac surgery, followed by musical intervention and hypnotherapy, considered cognitive-behavioral therapies [9].
Massage therapy proved effective in six of the eight studies [22, 25, 28, 30, 32, 33], and it also proved effective when combined with patient education [24]. Massage not only reduced anxiety [24, 25, 28, 32, 33] but also stress [28, 32] and fatigue [24].
The feet received the most attention [22, 25, 41], followed by the area indicated by the patient, which could be the head, neck, shoulders, arms, hands, back, legs, or feet [28, 33]. The duration of massage ranged from 10 to 30 minutes, with 20 minutes being the most common [22, 24, 28, 32, 33, 41].
A meta-analysis that evaluated the effect of massage on reducing perioperative anxiety and postoperative pain recommended that massage sessions should last 10 to 20 minutes in busy clinical settings [44].
A randomized clinical trial of 60 patients undergoing cardiac surgery found that, in addition to standard ICU care, a 20-minute massage session with moderate pressure on the hands could reduce the intensity and unpleasantness of pain and anxiety [45]. However, further research is needed on the optimal frequency, techniques, and duration of massage in the postoperative setting [33].
In a study conducted in Saudi Arabia with 31 patients, it was found that foot massage combined with pharmacological treatment can reduce pain, as there was a reduction of 2 to 3 points on the VAS, as well as a reduction in anxiety levels. In addition, this study addressed the importance of pain control, especially in the first four postoperative days [25].
Similarly, in a study of 152 patients, the authors found that massage therapy, used as an adjunct to standard treatment beginning on the third postoperative day, helped to relieve pain and reduce anxiety [28].
The effectiveness of massage therapy was demonstrated in a study conducted with 53 patients in the United States, which found a significant reduction in the level of pain in intensive care patients, as well as benefits related to the interrelationship between pain, relaxation, sleep, emotions, recovery, and other phases of healing [46].
In addition, massage therapy is considered a safe and inexpensive technique [25] that can be used as an adjunct to standard treatment to relieve discomfort while providing physical and psychological benefits during hospitalization [25, 28].
As health care professionals and patients become more aware of the benefits of massage therapy as an adjunct to conventional therapy, nurses will play an important role during patients' hospitalization by identifying the evidence and benefits of this technique for relieving pain and anxiety [47].
Regarding the efficacy of musical intervention, studies [20, 29, 37, 38, 40] have shown a significant reduction in postoperative pain and anxiety [20, 38, 40].
Background music and sedative music can be used in conjunction with pharmacological therapy to help patients recover after cardiac surgeries by reducing pain and anxiety [20, 29, 40]. In addition, musical intervention is low-risk and can be performed safely [20, 40].
In the studies analyzed, musical intervention was delivered through headphones or a music pillow at 20- to 30-minute intervals, with music preprogrammed by the researcher or chosen from a list by the patient. The music styles used were classical [20, 38, 40], jazz [38, 40], structured music with nature sounds [29], new age–style soft music [37], easy listening ("ambient music") [38], sedative music (synthesizer, harp, piano, orchestra, and flute) [40], and folk and pop [20]. A mixed randomized clinical trial with a quantitative and a qualitative phase conducted on 45 patients undergoing cardiac surgery found that a 15- or 30-minute session of musical intervention was effective in reducing pain. Pain intensity on the VAS was reduced by approximately two points, and the technique had a positive effect on reducing anxiety [48].
A meta-analysis of systematic reviews found that musical intervention was effective in reducing pain and anxiety in patients undergoing cardiac surgery and was a simple therapy to implement [49].
The effects of musical intervention on the relief of postoperative pain have been studied in a variety of surgical settings. A meta-analysis of 81 randomized clinical trials concluded that listening to music reduced pain and anxiety in adults undergoing surgery. However, it should be noted that the risk of bias in the studies ranged from moderate to high [50].
Further studies are needed on the effects of musical intervention on pain relief, as well as on the optimal duration of each session, the effects of repeated sessions, and the style of music [37, 38, 40].
Hypnosis, on the other hand, is a psychotherapeutic technique in which the hypnotist suggests changes in behavior, cognition, perception, affect, or mood [51, 52], which may help alleviate pain associated with medical procedures [54].
Only one of the four evaluations of hypnotherapy alone or in conjunction with other therapies [27] has demonstrated the effectiveness of the intervention in reducing pain after cardiac surgery. This study examined hypnosis in patients undergoing myocardial revascularization and found that it contributed to both pain relief and reduction of anxiety and stress. However, the authors emphasized that this technique should only be used by trained and certified teams [27].
Hypnotherapy has also been shown to be beneficial in other surgeries [55, 56] and procedures [57], although in some cases no statistically significant results were found [58]. In addition, one study found that hypnotic sedation may reduce the incidence of chronic pain in patients who have undergone mastectomy [53].
Although some studies have failed to demonstrate the efficacy of hypnosis for pain control in the postoperative period of cardiac surgery [21, 42], a meta-analysis of 85 clinical trials found that this therapy was able to significantly reduce pain in healthy patients exposed to a nociceptive stimulus, making it an attractive alternative to analgesics for most people [59]. Another meta-analysis of 50 studies found that pain relief had a positive outcome in surgical patients [60].
However, we emphasize the importance of conducting methodologically rigorous clinical trials with different populations to prove the efficacy and applicability of hypnosis in order to recommend this therapy [59], as well as to analyze the circumstances in which the beneficial effects of this therapy may occur [60].
Osteopathic manipulative treatment is a therapy whose results are well documented in the treatment of musculoskeletal disorders, especially low back pain; however, its application in other pathologies is still limited [61]. Despite the positive results found in an Italian study of 80 patients on the applicability of this therapy in the relief of pain after cardiac surgeries, further studies are needed to support the practice [26].
Although studies using ice packs, electroacupuncture, a set of complementary alternative therapies, scheduled rest, neurolinguistic programming, and guided imagery have shown positive results in reducing postoperative pain, individual studies are insufficient to recommend the clinical application of these therapies for pain relief after cardiac surgery.
Similarly, studies indicating the ineffectiveness of homeopathic treatment, guided relaxation, brief psychotherapy, and virtual reality in significantly reducing pain are insufficient to rule out their use as adjunctive methods to pharmacological analgesia.
In the absence of sufficient scientific evidence, the North American consensus of pain specialists neither recommends nor discourages the use of physical methods such as therapeutic massage, acupuncture, or cold therapy as adjuncts to the management of postoperative pain. In contrast, cognitive-behavioral therapies such as music intervention, hypnosis, guided imagery, and others have only moderate evidence and are only weakly recommended [9].
Moreover, studies show that these nonpharmacological therapies are safe, low-risk, and well accepted by patients, in addition to being inexpensive and easy to use [25, 26, 31, 39]. However, complementary therapies should be used in conjunction with pharmacological methods and not as a substitute [23].
The lack of meta-analysis is a potential limitation of the present systematic review, as the included studies were quite heterogeneous in evaluating different types of nonpharmacological therapies using different methods.