It was observed that vital signs data indicated a tendency to decrease or stabilize when the subject was exposed to music intervention. However, there is only statistical significance (p < 0.05), in blood pressure (BP), possibly due to the lack of significance, insufficient sample size and that the affected variables were within normal ranges.
Regarding the first, the mean SBP was reduced by 15.3 mmHg and the mean DBP by 9.6 mmHg with respect to the control group, in line with Do Amaral et al., who describe a 6 mmHg reduction in SBP values (11). Our results reinforce those obtained in other studies in which a normalization of BP is observed, reducing both SBP and DBP in surgical processes.
According to the literature consulted, exposure to music produces a decrease in anxiety associated with changes at a physiological level such as a decrease in BP (16, 17). Given the characteristics of care in an ALS ambulance, in our case, it was not possible to use scales to measure anxiety levels, but this decrease in BP has been reflected.
We observe that HR and RR present similar results to other studies (16, 18), finding significance in studies conducted in the hospital surgical environment (19) and intensive care patients (20).
The RF measurement was performed with an electromedicine sensor, which reduces the measurement bias, with the difference in the RR means being 0.6 breaths per minute, the lesser effect could be attributed to the fact that the music is chosen by the researcher and not the patient (21), and the time of exposure to music is less than in other studies in which the results obtained have been significant (22).
The results obtained in the SpO2 variable coincide with the studies carried out in other clinical settings (20, 22). We have not found any studies that register the EtCO2 variable.
Taking into account that one of the inclusion criteria is that the patient is conscious, the range in the BIS is narrowed. Values between 97 and 100 correspond to the awake, conscious, and active patient, taking the value of 90 as the patient's state without anxiety. With these references, we observe that the mean of the control group is 93.1 ± 6.4, compared to the mean of 92.3 ± 8.0 in the intervention group, in accordance with the findings of Maeyama et al. (23).
Several investigations have confirmed that music significantly reduces the perception of pain by the cancer patient (24), in patients undergoing surgical procedure (25, 26), as well as in the hospital emergency setting, and in hospital intensive care units (20, 22), where a decrease in the administration of analgesic drugs was observed (25).
The absence of significant VAS findings could be related to the low VAS levels found (mean of 1.1 vs. 1.2), both below 3, a value that some authors define in pain-free ranges (27).
When studying the impact of music on the administration of drugs during care, we find in the literature that Ayoub et al. (28), associate a decrease in anxiety of patients with spinal anaesthesia exposed to music intervention and with this, lower doses of Propofol administration, these data coinciding with similar studies (29). In this regard, studies stand out (10, 25, 27) in which the doses of drugs administered as sedation prior to a surgical procedure are decreased, as well as the doses of analgesic drugs during different invasive procedures.
Regarding the administration of drugs during the transfer, it is worth highlighting the results obtained in relation to the variable that encompasses cardiovascular drugs (nitrates and antihypertensive drugs) (p = 0.010), which implies that listening to music reduces the doses administered to these patients, a fact that acquires great relevance since interactions with other drugs and possible adverse effects could be avoided.
We were unable to compare these findings with other studies, since in general, the drugs that have been described in the different studies were related to the decrease in pain and anxiety, and not to treatments specifically related to drugs with a cardiovascular effect.