Anxiety is a common disorder that involves feeling of extreme fear or worry. It has been observed that many patients undergoing surgery experience anxiety. It has positive relationship with intraoperative and postoperative complication. There are various tools designed for measuring anxiety and all those tools have some limitations, among them state trait inventory questionnaire is considered most reliable tool as it has shown consistent result in various studies. It is a sensitive predictor of distress over time.
The incidence of significant preoperative anxiety in our study population was 36% by using STAI scale. Miguel et al.(5) also found the incidence of 32% while in other studies it varies from 20–92%(2, 9, 18). This wide range may be due to the use of different scales in different surgical patients. Type of population may also influence the incidence of anxiety as higher percentages are seen in western population (11, 19).
Determinant of high preoperative anxiety in various studies are prolonged waiting time, age under 65 year(5), fear of anaesthesia and surgery, lack of information about procedure, fear of postoperative pain and distorted body image and separation from family. Better preoperative consultation has shown to reduce anxiety (20, 21).
In the present study, although insignificant but preoperative anxiety was more common in female cardiac surgery patients than male patients (40.6% vs 33.8%). This is in line with the study by Mehdi et al. who suggested that the preoperative anxiety levels are much higher in female than male patients (1). Vilma et al.(22) also found higher anxiety in females. Although, the percentage of female patients was very low in the present study and difficult to conclude but previous studies have also shown the same trend(9).
No significant differences were found between preoperative anxiety and smoking, DM, HTN and BMI. Type of surgery (Valvular vs CABG) also had no significant effect on anxiety. Valve surgery patients were slightly more anxious preoperatively in comparison with CABG surgery patients. This is in contrast with other studies where CABG patients showed higher anxiety scores (23). Reason may be that in our study only 12 patients underwent valve surgery and rest were CABG surgery patients.
Study by H. Kil et al in 2011 concluded that patients with higher STAI scores required greater amount of induction and inhalational agent and also significantly associated with post-operative pain (24). We did not look at induction agent and inhalation requirements but intraoperative analgesia requirements were increased in moderate to severe anxiety group. Rather, Intraoperative analgesia requirements in the present study were significantly higher in moderate to severe anxiety group. Takenkara Shiho et al. proposed that high preoperative anxiety is associated with reduced intraoperative nociceptive response (changes in HR, SBP and perfusion index) and high postoperative response(25). This may be the reason that intraoperative narcotic consumption was lower than expected in their study. Preoperative Anxiety may also effect the intraoperative haemodynamics. Aysegul Bayrak et al. noticed higher HR and Blood pressure in anxiety group than non-anxiety or lower anxiety score groups(26). Post-operative pain scores were also higher in anxiety group. Marentes et al. demonstrated higher anaesthetic requirements in anxiety group but analgesic requirements were not mentioned in their study(27). In fact we were unable to find any study showing intraoperative analgesia requirements. We need further studies to look at this factor as well.
In our study, using standard analgesia protocol post-operative pain scores were found significantly higher in moderate to severe anxiety group as compared to mild anxiety group in first 24 hrs. As expected, the analgesic requirements were also significantly increased in moderate to severe anxiety group. This may be due to the fact that average pain score was moderate in anxiety group and mild in non-anxiety during first 12 hrs. Highly significant association was found when postoperative pain was compared between non anxious and anxious patients after adjusting age gender, type of surgery and other comorbids. Our study is in line with study by Miguel et al. who measured preoperative anxiety and depression using, Hospital anxiety and depression scale (HADS) and found significant correlation of pre-operative anxiety with post-operative pain(5). Analgesic consumption was also high in their study in anxiety group and remain high for 48 hours after extubation.
Study by Gresztat et al. in 2008 concluded that patients with higher preoperative anxiety respond poorly to analgesic medication, which may be due to increase perception of pain(28). It is difficult to say whether preoperative anxiety leads to change in pain intensity or the response to pain medications disturbed.
Ocalan et al. looked at ENT surgeries and found a positive relationship of preoperative anxiety and post-operative pain, but negative relationship of post-operative pain with depression. They also suggested early intervention to relieve preoperative anxiety(29). Other studies also concluded with same suggestions in various surgeries(18, 30).
Generally, female patients have higher pain scores than men(31). In the present study, male patients showed slightly higher mean postoperative pain scores, irrespective of groups during first 24 hours as compared to females. But the association between gender and postop pain was insignificant. Postop morphine requirement was higher in female patients than male but this association was insignificant.
Pregabalin has been used as an anxiolytic agent before neurosurgery and authors were able to demonstrate the anxiolytic effect and reduced postoperative analgesic requirements(32). It shows that anxiolysis does reduces postoperative analgesia need.
Significant association was also found between type of surgery and postoperative pain at 24 hrs. where postop pain was more at valvular surgery than CABG after adjusting other factors.
Further studies are required to see the effect of preoperative anti-anxiety medication on postoperative pain management. These medications can be started on surgical floors, night before surgery and continued till patient called for operative room. In addition it is the responsibility of doctor and nurse to educate patients about the procedure, and also take appropriate interventions, in order to reduce anxiety and post-operative morbidities. Another approach is to give ICU tour to patient and families before surgery in order to improve satisfaction and reduce anxiety(33).
Average age of the anxiety group was non-significantly lower than non-anxiety group. But postoperative pain was not affected by age except in 51 to 60 years group. There was no change in analgesic requirements for pain control in both the groups despite higher pain scores in anxiety group.
Our study also found that patients of anxiety group having duration of surgery more than 300 minutes had greatest post-operative pain scores(5.00 ± 1.41) at 12 hrs. which is moderate by our definition. This is significantly different for non-anxious patients who had mild pain at the same time but this difference abolished at 24 hrs.
The main limitation of the study was that the study was performed in only one centre and all factors responsible for anxiety were not considered
In conclusion, our study indicates that patients undergoing cardiac surgery and experienced moderate to severe anxiety before surgery are more prone to develop higher pain scores at post-operative period which is significantly different from mild group. Intraoperative and postoperative analgesic requirements were also significantly increased.