Analysis of the risk factors of postoperative respiratory dysfunction of type A aortic dissection and lung protection

Perioperative oxygenation impairment related to type a aortic dissection

Type A aortic dissection (TAAD) is a life-threatening disease with high mortality and poor prognosis, usually treated by surgery. There are many complications in its perioperative period, one of which is oxygenation impairment (OI). As a common complication of TAAD, OI usually occurs throughout the perioperative period of TAAD and requires prolonged mechanical ventilation (MV) and other supportive measures. The purpose of this article is to review the risk factors, mechanisms, and treatments of type A aortic dissection-related oxygenation impairment (TAAD-OI) so as to improve clinicians' knowledge about it. Among risk factors, elevated body mass index (BMI), prolonged extracorporeal circulation (ECC) duration, higher inflammatory cells and stored blood transfusion stand out. A reduced occurrence of TAAD-OI can be achieved by controlling these risk factors such as suppressing inflammatory response by drugs. As for its mechanism, it is currently believed that inflammatory signaling pathways play a major role in this process, including the HMGB1/RAGE signaling pathway, gut-lung axis and macrophage, which have been gradually explored and are expected to provide evidences revealing the specific mechanism of TAAD-OI. Numerous treatments have been investigated for TAAD-OI, such as nitric oxide (NO), continuous pulmonary perfusion/inflation, ulinastatin and sivelestat sodium, immunomodulation intervention and mechanical support. However, these measures are all aimed at postoperative TAAD-OI, and not all of the therapies have shown satisfactory effects. Treatments for preoperative TAAD-OI are not currently available because it is difficult to correct OI without correcting the dissection. Therefore, the best solution for preoperative TAAD-OI is to operate as soon as possible. At present, there is no specific method for clinical application, and it relies more on the experience of clinicians or learns from treatments of other diseases related to oxygenation disorders. More efforts should be made to understand its pathogenesis to better improve its treatments in the future.

Risk Factors for Prolonged Mechanical Ventilation After Pulmonary Endarterectomy: 7 Years' Experience From an Experienced Hospital in China

Background: Prolonged mechanical ventilation (PMV) is common after cardiothoracic surgery, whereas the mechanical ventilation strategy after pulmonary endarterectomy (PEA) has not yet been reported. We aim to identify the incidence and risk factors for PMV and the relationship between PMV and short-term outcomes.

Methods: We studied a retrospective cohort of 171 who undergoing PEA surgery from 2014 to 2020. Cox regression with restricted cubic splines was performed to identify the cutoff value for PMV. The Least absolute shrinkage and selection operator regression and logistic regressions were applied to identify risk factors for PMV. The impacts of PMV on the short-term outcomes were evaluated.

Results: PMV was defined as the duration of mechanical ventilation exceeding 48 h. Independent risk factors for PMV included female sex (OR 2.911; 95% CI 1.303–6.501; P = 0.009), prolonged deep hypothermic circulatory arrest (DHCA) time (OR 1.027; 95% CI 1.002–1.053; P = 0.036), increased postoperative blood product use (OR 3.542; 95% CI 1.203–10.423; P = 0.022), elevated postoperative total bilirubin levels (OR 1.021; 95% CI 1.007–1.034; P = 0.002), increased preoperative pulmonary artery pressure (PAP) (OR 1.031; 95% CI 1.014–1.048; P < 0.001) and elongated postoperative right ventricular anteroposterior dimension (RVAD) (OR 1.119; 95% CI 1.026–1.221; P = 0.011). Patients with PMV had longer intensive care unit stays, higher incidences of postoperative complications, and higher in-hospital medical expenses.

Conclusions: Female sex, prolonged DHCA time, increased postoperative blood product use, elevated postoperative total bilirubin levels, increased preoperative PAP, and elongated postoperative RVAD were independent risk factors for PMV. Identification of risk factors associated with PMV in patients undergoing PEA may facilitate timely diagnosis and re-intervention for some of these modifiable factors to decrease ventilation time and improve patient outcomes.

JAK2/STAT3 Pathway Was Associated with the Protective Effects of IL-22 On Aortic Dissection with Acute Lung Injury

Patients with aortic dissection (AD) may present acute lung injury (ALI) that may affect the prognosis. In this study, we aim to investigate the roles and mechanism of IL-22 in the pathogenesis of AD complicated with ALI. Six hundred and twenty-one AD patients were included, and the incidence of ALI and pulmonary CT findings were analyzed. Mouse ALI model was established through AngII, and then IL-22 injection and AG490 were given. The pathological changes, infiltration of inflammatory cells, and expression of STAT3 were determined. For the in vitro experiment, cultivated pulmonary microvascular endothelial cells (PMVECs) were treated by angiotensin II (AngII), followed by treating with IL-22 and/or AG490. The expression and migration of STAT3 was determined. Flow cytometry was carried out to evaluate the apoptosis. IL-22 contributed to the expression of STAT3 in lung tissues and attenuation of ALI. IL-22 obviously inhibited the apoptosis of PMVECs mediated by AngII and downregulated the expression and intranuclear transmission of STAT3. Such phenomenon was completely inhibited upon administration of AG490, an inhibitor of JAK2. Our data showed IL-22 contributed to the inhibition of PMVEC apoptosis mediated by AngII through activating the JAK2/STAT3 signaling pathway, which may attenuate the ALI induced by AngII.

Immediate ICU Care for Patients Following Aortic Arch Surgery

Patients undergoing aortic arch surgery are at high risk for stroke, delirium, low cardiac output, respiratory failure, renal failure, and coagulopathy. A significantly higher mortality is seen in patients experiencing any of these complications when compared with those without complications. As surgical, perfusion, and anesthetic techniques improve, the incidence of major complications have decreased. A recent paradigm shift in cardiac surgery has focused on rapid postoperative recovery, and a similar change has affected the care of patients after arch surgery. Nevertheless, a small subset of patients experience significant morbidity and mortality after aortic arch surgery, and rapid identification of any organ dysfunction and appropriate supportive care is critical in these patients. In this article, the current state of postoperative care of the patient after open aortic arch surgery will be reviewed.

Prolonged postoperative respiratory support after proximal thoracic aortic surgery: Is deep hypothermic circulatory arrest a risk factor?

PURPOSE

In addition to the pulmonary risks associated with cardiopulmonary bypass, thoracic aortic surgery using deep hypothermic circulatory arrest (DHCA) may subject the lungs to further injury. However, this topic has received little investigation to date.

MATERIALS AND METHODS

A prospective cohort review was performed on all patients undergoing proximal thoracic aortic surgery with (n = 478) and without (n = 135) DHCA between July 2005 and February 2013 at a single institution. The primary outcome was prolonged postoperative respiratory support (PPRS), defined as any of the following: >1 day of mechanical ventilation at either fraction of inspired oxygen >0.4 and/or positive end-expiratory pressure >5 mm Hg, >2 days of supplemental O2 requirement of at least 2.5 L/min, or discharge with new O2 requirement. Independent risk factors for PPRS were identified using multivariable logistic regression.

RESULTS

Postoperative respiratory support was required in 100 patients (20.9%) with and 30 patients (22.2%) without DHCA (P = .74). Independent predictors of PPRS after proximal aortic surgery included the following: age, diabetes, history of stroke, preoperative creatinine, American Society of Anesthesiologists class 4, redo-sternotomy, total arch replacement, and transfusion requirement. Use of DHCA was not an independent risk factor for PPRS in the entire cohort. Subanalysis of only DHCA patients revealed that longer DHCA times were independently associated with PPRS.

CONCLUSIONS

Prolonged postoperative respiratory support is common after proximal aortic surgery. The use of DHCA was not associated with this complication in the overall cohort, although longer DHCA times were predictive when only the subset of patients undergoing DHCA was analyzed. Knowledge of the risk factors for PPRS after proximal aortic surgery should improve preoperative risk stratification and postoperative management of these patients.