This study was a cross-sectional study conducted to confirm the knowledge and attitude of surgical ward nurses toward PCA to develop future PCA education programs for nurses. Our findings confirmed that the total score of nurses’ knowledge and attitudes was not high. Although the tool used in this study has not been previously used, the knowledge score was similar to previous studies [23, 25]. Knowledge and attitude scores, according to the general characteristics of nurses, were also similar to those found in previous studies [15,16,17, 23]. Previous studies [15,16,17, 23] confirmed that knowledge was greater, or attitudes were more appropriate, among nurses receiving pain management education, and similar results were confirmed in this study. However, in this study, 80% of nurses had previously received pain management education, including education on PCA. To increase the effectiveness of education programs, it is important to understand factors such as the clinical experience, and educational background, and insufficient knowledge areas of individual nurses. This study suggests that intensive education should target newly trained nurses, who have little clinical experience on the surgical ward and who have received no previous education on PCA.
Nurses’ knowledge of PCA
In this study, knowledge of opioid analgesics was relatively poorer than that of other areas, ranking second to fifth according to the overall incorrect answer rate (Table 2). However, awareness of addiction and respiratory depression, which have been identified as obstacles to sufficient postoperative pain control, was higher than that found in previous studies [1, 3, 6, 10, 19, 24]. Importantly, the question “If delirium occurs, PCA should be stopped” scored a high number of incorrect answers. Delirium is challenging in the postoperative recovery process, and nurses should be attentive to the use of opioid analgesics, particularly among the elderly. Postoperative pain may increase the occurrence of delirium, so PCA has been recommended [26, 27], although most nurses in this study were not aware of this recommendation. Additionally, among the drugs used in PCA, fentanyl citrate is known to be the safest drug for patients with impaired kidney function because it does not produce active metabolites that can cause side effects on the central nervous system . However, only half of the nurses were aware of this. Previous studies [5, 20], demonstrated that PCA was a safer and more effective analgesic method than PRN because dosing can compensate for differences between individuals regarding drug requirements, but about half of the nurses believed the opposite. Previous studies have shown that nurses’ knowledge of analgesics, particularly opioid analgesics, is limited [17,18,19, 25]. Similarly, our study found that the overall knowledge about opioid analgesics used in PCA among nurses in the surgical ward was insufficient. Therefore, the future PCA education programs for nurses should be followed by a basic understanding of opioid analgesics. It is necessary to check whether the knowledge of nurses has improved by the effect of education. Accordingly, it is also necessary to identify whether the patient’s pain control is appropriate, and the patient’s satisfaction is increased.
Nurses’ attitudes toward PCA
Like knowledge responses, the highest attitude scores were in the management domain, while inappropriate attitudes were observed in the opioid analgesic domain (Table 3). PCA opioid analgesics are not the only cause of nausea and vomiting occurring after surgery. However, in this study, over 50% of surgical ward nurses tended to stop PCA immediately when side effects manifested themselves. Nausea and vomiting are common postoperative complications caused by various factors including postoperative pain . Moreover, according to previous studies [5, 20], PRN administration showed no difference in the incidence of side effects, such as nausea and vomiting, compared with PCA use, and patients using PCA had good pain control, high satisfaction, and shorter hospital stays. Therefore, if the patient’s pain intensity is continuously severe, PCA should not be stopped only because patients exhibit symptoms of nausea and vomiting. Rather, nurses should be educated on how to simultaneously improve nausea, vomiting, and pain by combining PCA and antiemetic drugs. Therefore, when developing a PCA education program, the educational content should be organized so that it combines the side effects of opioid analgesics with the basic understanding of causes, risk factors, and management of postoperative nausea and vomiting.
As shown in Tables 2 and 3, most nurses provide PCA education immediately after surgery, and this finding was consistent with that of previous studies . However, it may be difficult for patients to accurately understand PCA immediately after surgery. Previous studies have confirmed that receiving this information before surgery has a higher educational effect [4, 8, 21]. Furthermore, Lin et al.  reported that patients educated about PCA before surgery, had a lower number of requests for help to the PCA nurse, which in turn increased work satisfaction for nurses. Therefore, it may be necessary to modify the policy of the entire hospital to increase both the satisfaction of nurses and patients when using PCA. It would be more effective to modify PCA policies regarding preoperative patient education at the hospital level rather than at the ward level or at the discretion if individual nurses.
Correlation between knowledge and attitude subdomains on PCA
In this study, two knowledge and three attitude subdomains showed significant correlations with one another (Table 4). Specifically, the greater the knowledge about opioid analgesics, the better the attitude toward opioid side effect management. Previous studies have reported that doctors’ and nurses’ knowledge and attitudes are also important in determining the effectiveness and safety of PCA . Furthermore, King and Walsh  reported that nurses’ fears of the effects and side effects of opioid analgesics disappeared after receiving education on PCA, and PCA education for patients became more effective. In this study, patients were also asked about their intentions regarding PCA education, and 95.7% of nurses answered that they required further education. Among the six domains investigated, the need for managing the side effects of opioid analgesics was the highest (66.7%), followed by basic knowledge education on opioid analgesics (47.9%). And nurses preferred a shortened PCA education program time of less than 30 minutes (53.8%). Therefore, the education program should consist of different domains including basic knowledge, opioid side effects, and the management of side effects. Role-playing exercises and case studies should also be actively utilized because they can confirm the status of nurses’ knowledge and evaluate whether the nurses demonstrate appropriate attitudes toward patient pain management.
Factors affecting nurses’ knowledge and attitudes toward PCA
As set out in Tables 1 and 5, there was an association between the type of ward in which the nurse worked, and the knowledge acquired by nurses. Low knowledge scores were found among nurses on the musculoskeletal surgical ward and there was also a higher percentage of persons discontinuing PCA . Since musculoskeletal surgical ward patients take oral painkillers earlier than patients on abdominal surgical wards, the use of PCA may be affected. Nevertheless, the reasons underlying the differences among nurses are uncertain. It is important to first identify these reasons and then provide targeted intensive education where required. It would also be useful to develop an educational program that compares the causes of different educational results after nurses receive PCA education in pairs between ward nurses who had a positive approach to nursing education and nurses who did not. Through this approach, nurses can independently identify the causes of the different educational results and help each other to increase their knowledge.
Limitations and meanings
From a total of 22 surgical wards of tertiary hospital A, 8 surgical wards were selected in this study and sampled using the cluster sampling method. Since this study did not apply to all surgical ward nurses at a tertiary hospital, it is difficult to generalize the results to all surgical ward nurses. Furthermore, the knowledge and attitude scores may be lower in hospitals that are smaller than those included in this study and where pain management education including PCA is not regularly conducted. This cross-sectional study has all the limitations and risks of bias inherent to cross-sectional studies. Specifically, as participants of various ages with different empirical backgrounds were sampled at the same time, the effect of exogenous variables, such as clinical experience, cannot be reduced, and this sample cannot represent all age groups. We consider that further studies should verify the validity and reliability of the tools developed and used in this study.
Nevertheless, the results of this study can be considered meaningful. Most previous studies have measured the overall knowledge and attitude of nurses toward pain management. There are few studies confirming nurses’ knowledge and attitudes toward PCA, and these did not specifically identify the weak and strong parts of PCA education. The strength of this study was that it identified which aspects of nurses’ knowledge and attitudes were vulnerable and what types of intensive education are necessary when educating about PCA.