Depression, Post-Op Infections, and Wound Healing after CABG Surgery
Abstract & Commentary
By Karen Johnson, RN, PhD, Professor, School of Nursing, University of Maryland, is Associate Editor for Critical Care Alert
Dr. Johnson reports no financial relationship to this filed of study.
Synopsis: When assessed 2 or 3 days after extubation, at hospital discharge, and again 6 weeks following coronary artery bypass grafting, patients with depressive symptoms had more wound infections and delayed wound healing than patients without evidence for depression.
Source: Doering LV, et al. Depression, healing, and recovery from coronary artery bypass surgery. Am J Crit Care. 2005;14:316-324.
Doering and colleagues used a nonrandomized, comparative, longitudinal design to study 72 patients after CABG surgery to investigate the association among depressive symptoms, infections, and impaired wound healing. Data were collected at 3 time points post-operatively: within 48 hours after extubation, at the time of discharge from the hospital, and 6 weeks after discharge. Depressive symptoms were measured using the Multiple Affect Adjective Check List (MAACL). Physical recovery was measured by using the 6-minute walk test, the Wolfer-Davis Recovery Index, the physical health composite score of the Short Form 12 (SF-12) and a chart review to determine documented infections and episodes of prolonged wound healing required treatment.
Mean scores for the depressive symptoms were high at all 3 time points: mean scores for depressive symptoms on the MAACL were 19.8 (SD, 6.3), 18.8 (SD, 7.1), and 16.4 (SD, 7.8) respectively. At these 3 respective time points, this represents 92%, 88%, and 72% of the patients in the sample scoring higher than the population norm of 11. The highest incidence of depressive symptoms occurred within 48 hours of extubation (typically post-op day 2-3). Patients with higher depression scores at discharge were 3.7 times more likely than patients with lower depression scores to experience wound infections and wound healing problems 6 weeks after discharge (odds ratio, 3.7; 95% CI, 1.15-12.0; P = .03). These findings persisted even when the effects of age, diabetes and obesity were statistically controlled for. Patients with higher depressive scores also had shorter walking distances on the 6-minute walk test than did patients with lower depressive scores.
This is one of the first studies to establish a relationship between depressive symptoms and infections and impaired wound healing after CABG. This study found a high prevalence of depressive symptoms after CABG, and linked these symptoms to adverse outcomes after surgery.
The high prevalence of depressive symptoms reported in this study is alarming. The highest scores were within 48 hours post-extubation, typically on post-op day 2-3. Although this prevalence is striking, it is not clinically surprising. It is typically on about post-op day 2-3 that patients—irrespective of the type of surgery done—seem to have bad days. We tell them to expect it, but we do little about it. Doering et al postulate that feelings of depression are intensified in the first few post-op days as a result of pain, sleep deprivation, isolation, and loss of control. We have to continue to strive to do a much better job at controlling these factors.
Since Doering et al did not begin data collection until 48 hours post-extubation, we do not know how many of these patients were depressed pre-operatively. There is a long-standing link between depression and chronic cardiovascular disease. Over a third of the patients in this study carried diagnoses of chronic cardiovascular disease, because 36% of them had had a previous myocardial infarction or CABG procedure. It would be interesting to see if these findings could be replicated in patients with no previous experience with myocardial infarction or CABG, and in non-cardiac surgery patients postoperatively.
The association between depression, delayed wound healing, and infection is most likely due to hypothalamic-pituitary-adrenal (HPA) reactivity as a response to the stress. Critical illness, anesthesia, surgery, trauma, burns, hemorrhage, infection, pain, cold, fever, and emotional disorders are stressors that activate the HPA axis.1,2 When faced with such a stressor, the hypothalamus releases corticotropin releasing hormone, which in turn stimulates the anterior pituitary to release adrenal corticotropin hormone (ACTH), which then stimulates the adrenal cortex to release both the mineralocorticoid, aldosterone (to promote intravascular fluid retention) and the glucocorticoid, cortisol (to increase availability of substrates for metabolism and modulate the immune/inflammatory response). The HPA axis is an essential component of the general adaptation to stress, and plays a crucial role in cardiovascular, metabolic, and immunologic homeostasis. However, cortisol has a profound effect on the inflammatory process as it inhibits the functions of almost every cell involved in inflammation. This inhibition is mediated by altering the transcription of cytokine genes (eg, for Interleukins 1 and 6) and by inhibiting the production of proinflammatory substances (such as leukotrienes and prostaglandins).3
If we are going to make an impact on the negative association between depression and impaired wound healing, we need to start with controlling or mitigating the physical and emotional response to the stress of surgery and the environments we place patients to heal. This study highlights the importance of assessing our patients’ emotional health, in addition to their physical health postoperatively, because emotional health influences patient outcomes.
- Lamberts SW, et al. Corticosteroid therapy in severe illness. N Engl J Med. 1997;337:1285-1292.
- Marik PE, Zaloga GP. Adrenal insufficiency in the critically ill: A new look at an old paradigm. Chest. 2002; 122:1784-1796.
- O’Connor TM, et al. The stress response and the hypothalamic-pituitary axis: from molecule to melancholia. QJM. 2000;93:323-333.