Comparison Between Dexmedetomidine and Propofol on Outcomes After Coronary Artery Bypass Graft Surgery

A Retrospective Study

Jie Hu; Bingfeng Lv; Raha West; Xingpeng Chen; Yali Yan; Chen Pac Soo; Daqing Ma

Disclosures

BMC Anesthesiol. 2022;22(51) 

In This Article

Discussion

In this large retrospective study of 1388 patients, the perioperative use of DEX shows an overall reduction in postoperative pulmonary complications, duration of mechanical lung ventilation, wound dehiscence or infection, length of ICU and hospital stay. Hypoxemia, atelectasis, pneumonia and bronchospasm are common in patients after cardiac surgery. In this study, these postoperative pulmonary complications tend to be less in the DEX group than in the propofol group, but only atelectasis was statistically significant. Atelectasis could be significantly less in the DEX group due to the reduction of lung inflammation, sputum stasis, and the association with reduction in the ICU mechanical lung ventilation time and is conducive to lung recruitment.[14]

DEX has been reported to suppress oxidative stress and inflammatory response in the lung[15] and diminish the severity of acute lung injury produced by remote organ ischemia-reperfusion.[16] The pulmonary protective properties may explain the finding of overall improvement in postoperative pulmonary complications. Our finding was in accordance with a recent meta-analysis of nine randomised controlled trials with a total of 1308 patients. DEX use was also associated with lower incidences of pulmonary complications and less mechanical ventilation time.[8] However, unlike our findings, they did not find any significant differences in other postoperative complications, length of ICU or hospital stay, despite previous systemic review and meta-analysis showing the significant reduction.[7] For 30-day mortality, unlike the previous findings,[7] we did not find a significant result for DEX; if anything, DEX was trending towards worse 30-day mortality.

When comparing the preoperative factors to match the propofol and DEX group, we found that arrhythmia and alcoholism were significantly more prevalent in the propofol than in the DEX group. However, upon multivariate logistic regression analysis for postoperative pulmonary complications, we did not find these two factors to worsen postoperative pulmonary complications and therefore did not influence the primary outcome in the propofol group.

We found that patients who had DEX could be extubated three hours earlier than patients who received propofol. These findings fit with DEX's well-described properties as a compliant, conscious sedative drug that allows more accessible assessment of conscious level, communication between patient and staff, and better pain control.[3] Our study also found the analgesic properties of DEX, where we showed that the group which received DEX required significantly less opioid than the propofol group.

The perioperative administration of DEX has been shown to reduce surgical stress, inflammatory response and preserve the immune cell function following surgery. DEX could significantly reduce the surge of epinephrine, cortisol, interleukin-6 and tumour necrosis factor-α following cardiac surgery.[6] DEX may reduce postoperative complications such as wound dehiscence or infection, as demonstrated in our study, by alleviating excessive surgical stress and inflammatory response.[6] These, together with its cytoprotective effects, might lead to an overall improvement in clinical outcomes.

To the best of our knowledge, our study is the first study to demonstrate that the use of DEX during cardiac surgery may shorten the surgical time compared to propofol. Other studies that compared the duration of surgery between the use of DEX and the controlled group (any treatment without DEX) have not produced a similar finding.[17] However, although not statistically significant, most of these studies were leaning to favour DEX in reducing cardiac surgery duration.[17] DEX has been shown to produce haemodynamic stability with significant beneficial effects on systolic arterial pressure, mean arterial blood pressure, pulmonary artery mean pressure, heart rate and reducing the incidence of hemodynamic complications.[9,17] These proven benefits may render less intra-operative haemodynamic instability; in particular, slowing down heart rate can enhance better-suturing performance by surgeons and hence reduce surgery time; all of which are useful during cardiac surgery and lead to less surgical time. However, this will need further investigation.

Our study did not find that DEX prevented the occurrence of new onset of cardiac arrhythmias in the postoperative period any more than propofol. This finding is in keeping with those from a recent RCT and observational study.[18,19] Evidence from other studies remains variable; for example, some studies found the incidence of atrial fibrillation was reduced following the administration of DEX.[20,21]

The cytoprotective effects of DEX on multi-organs have been well documented in the brain, lung, and kidney.[21–25] In oxidative stress-induced lung injury, DEX increased alveolar cell survival and proliferation by activating the protective signalling pathways in lung cells and preventing cellular apoptosis.[24] Both the anti-inflammatory and α2 adrenergic receptor-dependent mechanisms provide lung protection against acute lung injury.[26] DEX provides renal protection via the anti-inflammatory effects of the parasympathetic system activation in addition to its direct actions on the α2-adrenergic receptor.[22] Serine/threonine-protein kinase, a pathway that plays a crucial role in cytoprotective signalling, is activated by DEX, leading to the reduction in the pathological changes following ischaemia-reperfusion injury in the kidneys. DEX also attenuates Toll-like Receptor 4 (TLR4) expression in tubular cells, which leads to decreased tubular epithelial cell death.[23] All these findings above indicate that DEX may improve short/long term surgical (including cardiac surgeries) outcomes.

Our finding that CPB assistance decreased postoperative pulmonary complications conflicted with previous studies. Multiple inflammatory responses following CPB use has been described as the major causes of pulmonary damage following on-pump CABG surgery.[27] In several studies comparing on-pump and off-pump CABG, CPB used was associated with a significant increase in postoperative pulmonary complications such as pneumonia.[28,29] Although one study did not find a significant difference in postoperative lung function tests.[28] We used CPB assistance in a specific group of patients with circulatory instability following acute myocardial infarction and heart failure, and therefore our finding cannot be generalized. The correlation between diabetes and postoperative pulmonary complication has also been described as controversial.[27] Although we found that diabetes may worsen postoperative pulmonary complications, another study found no significant difference in pulmonary complications following CABG between patients with or without diabetes.[30] Postoperative factors such as sternotomy infection may negatively affect pulmonary complications,[31] as we found.

The strength of this study lies in the inclusion of a large number of patients of a specific type of cardiac CABG surgery, eliminating heterogeneity between different types of cardiac surgery and any potential varied procedural impact on outcomes. However, there are limitations to this study. First, this study is retrospective, which means that there are limitations in interpreting the results for the general patient population or making any concrete conclusions. Second, other postoperative complications were not assessed postoperatively, particularly postoperative delirium, which is prevalent in cardiac surgery. Third, the lung complications between the two groups were marginally different. Lastly, the underlying mechanisms for why DEX reduced postoperative lung complications and enhanced postoperative recovery remain unknown. All warrant further study in the future.

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