Risk of Early Postoperative Cardiovascular and Cerebrovascular Complication in Patients with Preoperative COVID-19 Undergoing Cancer Surgery

BACKGROUND

As the COVID-19 pandemic shifts to an endemic phase, an increasing proportion of patients with cancer and a preoperative history of COVID-19 will require surgery. This study aimed to assess the influence of preoperative COVID-19 on postoperative risk for major adverse cardiovascular and cerebrovascular events (MACEs) among those undergoing surgical cancer resection. Secondary objectives included determining optimal time-to-surgery guidelines based on COVID-19 severity and discerning the influence of vaccination status on MACE risk.

STUDY DESIGN

National COVID Cohort Collaborative Data Enclave, a large multi-institutional dataset, was used to identify patients that underwent surgical cancer resection between January 2020 and February 2023. Multivariate regression analysis adjusting for demographics, comorbidities, and risk of surgery was performed to evaluate risk for 30-day postoperative MACE.

RESULTS

Of 204,371 included patients, 21,313 (10.4%) patients had a history of preoperative COVID-19. History of COVID-19 was associated with an increased risk for postoperative composite MACE as well as 30-day mortality. Among patients with mild disease who did not require hospitalization, MACE risk was elevated for up to 4 weeks after infection. Postoperative MACE risk remained elevated more than 8 weeks after infection in those with moderate disease. Vaccination did not reduce risk for postoperative MACE.

CONCLUSIONS

Together, these data highlight that assessment of the severity of preoperative COVID-19 infection should be a routine component of both preoperative patient screening as well as surgical risk stratification. In addition, strategies beyond vaccination that increase patients' cardiovascular fitness and prevent COVID-19 infection are needed.

A nomogram model to predict the portal vein thrombosis risk after surgery in patients with pancreatic cancer

Background

Portal vein thrombosis (PVT) is a common postoperative complication in patients with pancreatic cancer (PC), significantly affecting their quality of life and long-term prognosis. Our aim is to establish a new nomogram to predict the risk of PVT after PC surgery.

Method

We collected data from 416 patients who underwent PC surgery at our hospital between January 2011 and June 2022. This includes 87 patients with PVT and 329 patients without PVT. The patients were randomly divided into a training group and a validation group at a ratio of 7:3. We constructed a nomogram model using the outcomes from both univariate and multivariate logistic regression analyses conducted on the training group. The nomogram's predictive capacity was assessed using calibration curve, receiver operating characteristic (ROC) curve, and decision curve analysis (DCA).

Results

In the study, the prevalence of PVT was 20.9%. Age, albumin, vein reconstruction and preoperative D-dimer were independent related factors. The model achieved a C-index of 0.810 (95% confidence interval: 0.752-0.867), demonstrating excellent discrimination and calibration performance. The area under the ROC curve of the nomogram was 0.829 (95% CI: 0.750-0.909) in the validation group. DCA confirmed that the nomogram model was clinically useful when the incidence of PVT in patients was 5%-60%.

Conclusion

We have established a high-performance nomogram for predicting the risk of PVT in patients undergoing PC surgery. This will assist clinical doctors in identifying individuals at high risk of PVT and taking appropriate preventive measures.

Intraoperative intravenous infusion of lidocaine increases total and small vessel densities of sublingual microcirculation: a randomized prospective pilot study

OBJECTIVE

Multiple organ failure can occur as a result of postoperative complications. Research has indicated that the underlying mechanism of organ dysfunction is a microcirculation disorder. Because of its antioxidant and anti-inflammatory properties, lidocaine has the potential to improve microvascular blood flow. This study was performed to assess the effect of intraoperative intravenous lidocaine infusion on the microcirculation and determine the incidence of postoperative complications.

METHODS

In this prospective randomized double-blind pilot study, 12 patients scheduled for abdominal surgery were randomly allocated to receive an intraoperative infusion of either 1% lidocaine or the same volume of 0.9% sodium chloride solution. The microcirculation was monitored using sidestream dark-field imaging and the vascular occlusion test combined with near-infrared spectroscopy.

RESULTS

Lidocaine significantly increased the total vascular density and small vessel density after 2 hours of infusion, with preservation of 99% to 100% of the capillary perfusion in both groups. No patients developed organ failure.

CONCLUSIONS

An increase in vessel density may be beneficial in major abdominal surgeries because it is associated with better tissue perfusion and oxygen delivery. However, this finding requires further investigation in patients with increased surgical risk. Overall, this study indicates that lidocaine has potential to improve microvascular perfusion.Research Registry number: 9549 (https://www.researchregistry.com/browse-the-registry#home/registrationdetails/650ffd27b3f547002bd7635f/).

Myocardial injury and long-term oncological outcomes in patients undergoing surgery for colorectal cancer

PURPOSE

Myocardial injury after noncardiac surgery (MINS) is associated with increased mortality and postoperative complications. In patients with colorectal cancer (CRC), postoperative complications are a risk factor for cancer recurrence and disease-free survival. This study investigates the association between MINS and long-term oncological outcomes in patients with CRC in an ERAS setting.

METHODS

This retrospective cohort study was conducted at Zealand University Hospital, Denmark, between June 2015 and July 2017. Patients undergoing CRC surgery were included if troponin was measured twice after surgery. Outcomes were all-cause mortality, recurrence, and disease-free survival within five years of surgery.

RESULTS

Among 586 patients, 42 suffered MINS. After five years, 36% of patients with MINS and 26% without MINS had died, p = 0.15. When adjusted for sex, age and UICC, the hazard ratio (aHR) for 1-year all-cause mortality, recurrence, and disease-free survival were 2.40 [0.93-6.22], 1.47 [0.19-11.29], and 2.25 [0.95-5.32] for patients with MINS compared with those without, respectively. Further adjusting for ASA status, performance status, smoking, and laparotomies, the aHR for 3- and 5-year all-cause mortality were 1.05 [0.51-2.15] and 1.11 [0.62-1.99], respectively. Similarly, the aHR for 3- and 5-year recurrence were 1.38 [0.46-4.51], and 1.49 [0.56-3.98] and for 3- and 5-year disease-free survival the aHR were 1.19 [0.63-2.23], and 1.19 [0.70-2.03].

CONCLUSION

In absolute numbers, we found no difference in all-cause mortality and recurrence in patients with and without MINS. In adjusted Cox regression analyses, the hazard was increased for all-cause mortality, recurrence, and disease-free survival in patients with MINS without reaching statistical significance.

Preoperative SARS-CoV-2 infection increases risk of early postoperative cardiovascular complications following noncardiac surgery

As the coronavirus disease 2019 (COVID-19) pandemic progresses to an endemic phase, a greater number of patients with a history of COVID-19 will undergo surgery. Major adverse cardiovascular and cerebrovascular events (MACE) are the primary contributors to postoperative morbidity and mortality; however, studies assessing the relationship between a previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and postoperative MACE outcomes are limited. Here, we analyzed retrospective data from 457,804 patients within the N3C Data Enclave, the largest national, multi-institutional data set on COVID-19 in the United States. However, 7.4% of patients had a history of COVID-19 before surgery. When comorbidities, age, race, and risk of surgery were controlled, patients with preoperative COVID-19 had an increased risk for 30-day postoperative MACE. MACE risk was influenced by an interplay between COVID-19 disease severity and time between surgery and infection; in those with mild disease, MACE risk was not increased even among those undergoing surgery within 4 wk following infection. In those with moderate disease, risk for postoperative MACE was mitigated 8 wk after infection, whereas patients with severe disease continued to have elevated postoperative MACE risk even after waiting for 8 wk. Being fully vaccinated decreased the risk for postoperative MACE in both patients with no history of COVID-19 and in those with breakthrough COVID-19 infection. Together, our results suggest that a thorough assessment of the severity, vaccination status, and timing of SARS-CoV-2 infection must be a mandatory part of perioperative stratification.NEW & NOTEWORTHY With an increasing proportion of patients undergoing surgery with a prior history of COVID-19, it is crucial to understand the impact of SARS-CoV-2 infection on postoperative cardiovascular/cerebrovascular risk. Our work assesses a large, national, multi-institutional cohort of patients to highlight that COVID-19 infection increases risk for postoperative major adverse cardiovascular and cerebrovascular events (MACE). MACE risk is influenced by an interplay between disease severity and time between infection and surgery, and full vaccination reduces the risk for 30-day postoperative MACE. These results highlight the importance of stratifying time-to-surgery guidelines based on disease severity.

Effect of Remote Ischaemic Preconditioning on Perioperative Endothelial Dysfunction in Non-Cardiac Surgery: A Randomised Clinical Trial

Endothelial dysfunction result from inflammation and excessive production of reactive oxygen species as part of the surgical stress response. Remote ischemic preconditioning (RIPC) potentially exerts anti-oxidative and anti-inflammatory properties, which might stabilise the endothelial function after non-cardiac surgery. This was a single centre randomised clinical trial including 60 patients undergoing sub-acute laparoscopic cholecystectomy due to acute cholecystitis. Patients were randomised to RIPC or control. The RIPC procedure consisted of four cycles of five minutes of ischaemia and reperfusion of one upper extremity. Endothelial function was assessed as the reactive hyperaemia index (RHI) and circulating biomarkers of nitric oxide (NO) bioavailability (L-arginine, asymmetric dimethylarginine (ADMA), L-arginine/ADMA ratio, tetra- and dihydrobiopterin (BH4 and BH2), and total plasma biopterin) preoperative, 2–4 h after surgery and 24 h after surgery. RHI did not differ between the groups (p = 0.07). Neither did levels of circulating biomarkers of NO bioavailability change in response to RIPC. L-arginine and L-arginine/ADMA ratio was suppressed preoperatively and increased 24 h after surgery (p < 0.001). The BH4/BH2-ratio had a high preoperative level, decreased 2–4 h after surgery and remained low 24 h after surgery (p = 0.01). RIPC did not influence endothelial function or markers of NO bioavailability until 24 h after sub-acute laparoscopic cholecystectomy. In response to surgery, markers of NO bioavailability increased, and oxidative stress decreased. These findings support that a minimally invasive removal of the inflamed gallbladder countereffects reduced markers of NO bioavailability and increased oxidative stress caused by acute cholecystitis.

The comparative and added prognostic value of biomarkers to the Revised Cardiac Risk Index for preoperative prediction of major adverse cardiac events and all-cause mortality in patients who undergo noncardiac surgery

BACKGROUND

The Revised Cardiac Risk Index (RCRI) is a widely acknowledged prognostic model to estimate preoperatively the probability of developing in-hospital major adverse cardiac events (MACE) in patients undergoing noncardiac surgery. However, the RCRI does not always make accurate predictions, so various studies have investigated whether biomarkers added to or compared with the RCRI could improve this.

OBJECTIVES

Primary: To investigate the added predictive value of biomarkers to the RCRI to preoperatively predict in-hospital MACE and other adverse outcomes in patients undergoing noncardiac surgery. Secondary: To investigate the prognostic value of biomarkers compared to the RCRI to preoperatively predict in-hospital MACE and other adverse outcomes in patients undergoing noncardiac surgery. Tertiary: To investigate the prognostic value of other prediction models compared to the RCRI to preoperatively predict in-hospital MACE and other adverse outcomes in patients undergoing noncardiac surgery.

SEARCH METHODS

We searched MEDLINE and Embase from 1 January 1999 (the year that the RCRI was published) until 25 June 2020. We also searched ISI Web of Science and SCOPUS for articles referring to the original RCRI development study in that period.

SELECTION CRITERIA

We included studies among adults who underwent noncardiac surgery, reporting on (external) validation of the RCRI and: - the addition of biomarker(s) to the RCRI; or - the comparison of the predictive accuracy of biomarker(s) to the RCRI; or - the comparison of the predictive accuracy of the RCRI to other models. Besides MACE, all other adverse outcomes were considered for inclusion.

DATA COLLECTION AND ANALYSIS

We developed a data extraction form based on the CHARMS checklist. Independent pairs of authors screened references, extracted data and assessed risk of bias and concerns regarding applicability according to PROBAST. For biomarkers and prediction models that were added or compared to the RCRI in ≥ 3 different articles, we described study characteristics and findings in further detail. We did not apply GRADE as no guidance is available for prognostic model reviews.

MAIN RESULTS

We screened 3960 records and included 107 articles.   Over all objectives we rated risk of bias as high in ≥ 1 domain in 90% of included studies, particularly in the analysis domain. Statistical pooling or meta-analysis of reported results was impossible due to heterogeneity in various aspects: outcomes used, scale by which the biomarker was added/compared to the RCRI, prediction horizons and studied populations.  Added predictive value of biomarkers to the RCRI Fifty-one studies reported on the added value of biomarkers to the RCRI. Sixty-nine different predictors were identified derived from blood (29%), imaging (33%) or other sources (38%). Addition of NT-proBNP, troponin or their combination improved the RCRI for predicting MACE (median delta c-statistics: 0.08, 0.14 and 0.12 for NT-proBNP, troponin and their combination, respectively). The median total net reclassification index (NRI) was 0.16 and 0.74 after addition of troponin and NT-proBNP to the RCRI, respectively. Calibration was not reported. To predict myocardial infarction, the median delta c-statistic when NT-proBNP was added to the RCRI was 0.09, and 0.06 for prediction of all-cause mortality and MACE combined. For BNP and copeptin, data were not sufficient to provide results on their added predictive performance, for any of the outcomes. Comparison of the predictive value of biomarkers to the RCRI  Fifty-one studies assessed the predictive performance of biomarkers alone compared to the RCRI. We identified 60 unique predictors derived from blood (38%), imaging (30%) or other sources, such as the American Society of Anesthesiologists (ASA) classification (32%). Predictions were similar between the ASA classification and the RCRI for all studied outcomes. In studies different from those identified in objective 1, the median delta c-statistic was 0.15 and 0.12 in favour of  BNP and NT-proBNP alone, respectively, when compared to the RCRI, for the prediction of MACE. For C-reactive protein, the predictive performance was similar to the RCRI. For other biomarkers and outcomes, data were insufficient to provide summary results. One study reported on calibration and none on reclassification. Comparison of the predictive value of other prognostic models to the RCRI   Fifty-two articles compared the predictive ability of the RCRI to other prognostic models. Of these, 42% developed a new prediction model, 22% updated the RCRI, or another prediction model, and 37% validated an existing prediction model. None of the other prediction models showed better performance in predicting MACE than the RCRI. To predict myocardial infarction and cardiac arrest, ACS-NSQIP-MICA had a higher median delta c-statistic of 0.11 compared to the RCRI. To predict all-cause mortality, the median delta c-statistic was 0.15 higher in favour of ACS-NSQIP-SRS compared to the RCRI. Predictive performance was not better for CHADS₂, CHA₂DS₂-VASc, R₂CHADS₂, Goldman index, Detsky index or VSG-CRI compared to the RCRI for any of the outcomes. Calibration and reclassification were reported in only one and three studies, respectively.

AUTHORS' CONCLUSIONS

Studies included in this review suggest that the predictive performance of the RCRI in predicting MACE is improved when NT-proBNP, troponin or their combination are added. Other studies indicate that BNP and NT-proBNP, when used in isolation, may even have a higher discriminative performance than the RCRI. There was insufficient evidence of a difference between the predictive accuracy of the RCRI and other prediction models in predicting MACE. However, ACS-NSQIP-MICA and ACS-NSQIP-SRS outperformed the RCRI in predicting myocardial infarction and cardiac arrest combined, and all-cause mortality, respectively. Nevertheless, the results cannot be interpreted as conclusive due to high risks of bias in a majority of papers, and pooling was impossible due to heterogeneity in outcomes, prediction horizons, biomarkers and studied populations. Future research on the added prognostic value of biomarkers to existing prediction models should focus on biomarkers with good predictive accuracy in other settings (e.g. diagnosis of myocardial infarction) and identification of biomarkers from omics data. They should be compared to novel biomarkers with so far insufficient evidence compared to established ones, including NT-proBNP or troponins. Adherence to recent guidance for prediction model studies (e.g. TRIPOD; PROBAST) and use of standardised outcome definitions in primary studies is highly recommended to facilitate systematic review and meta-analyses in the future.

The effect of pre-operative methylprednisolone on postoperative delirium in elderly patients undergoing gastrointestinal surgery: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Pre-operative administration of methylprednisolone reduced circulating markers of endothelial activation. This randomized, double-blind was to evaluate whether a single pre-operative dose of methylprednisolone reduced the rate of postoperative delirium (POD) in older patients undergoing gastrointestinal surgery, and its association with the shedding of endothelial glycocalyx markers.

METHODS

168 patients, aged 65-80 years and scheduled for laparoscopic gastrointestinal surgery, were randomized to 2 mg·kg -1 methylprednisolone (Group M, n = 84); or equivalent dose of placebo (Group C, n = 84). The primary outcome was the incidence of delirium during the first 5 days after surgery, assessed by the confusion assessment method (CAM). POD severity was rated daily using CAM-Severity (CAM-S). Level of syndecan-1, heparan sulfate, tumor necrosis factor-α(TNF-α), and brain-derived neurotrophic factor (BDNF) were measured at baseline, 1-day, and 3-day after surgery.

RESULTS

Compared with placebo, methylprednisolone greatly reduced the incidence of delirium at 72 h following surgery [9(10.7%) versus 20(23.8%), P =0.03, OR=2.22(95%CI 1.05-4.59)]. No between-group difference was found in the cumulative CAM-S score (P=0.14). The levels of heparan sulfate, syndecan-1, and TNF-α in Group M were lower than that in Group C (P <0.05 and P <0.01), while the level of BDNF in Group M was higher than that in Group C (P <0.01).

CONCLUSIONS

Pre-operative administration of methylprednisolone does not reduce the severity of POD, but may reduce the incidence of delirium after gastrointestinal surgery in elderly patients, which may be related to a reduction in circulating markers of endothelial degradation, followed by the increase of BNDF level.

Impaired vascular endothelial function as a perioperative risk predictor - a prospective observational trial

Background

In the recent years, an increasing number of patients with multiple comorbidities (e.g. coronary artery disease, diabetes, hypertension) presents to the operating room. The clinical risk factors are accompanied by underlying vascular-endothelial dysfunction, which impairs microcirculation and may predispose to end-organ dysfunction and impaired postoperative outcome. Whether preoperative endothelial dysfunction identifies patients at risk of postoperative complications remains unclear. In this prospective observational study, we tested the hypothesis that impaired flow-mediated dilation (FMD), a non-invasive surrogate marker of endothelial function, correlates with Days at Home within 30 days after surgery (DAH30). DAH30 is a patient-centric metric that captures postoperative complications and importantly also hospital re-admissions.

Methods

Seventy-one patients scheduled for major abdominal surgery were enrolled. FMD was performed pre-operatively prior to major abdominal surgery and patients were dichotomised at a threshold value of 10%. FMD was then correlated with DAH30 (primary endpoint) and postoperative complications (secondary endpoints).

Results

DAH30 did not differ between patients with reduced FMD and normal FMD (14 (4) (median (IQR)) vs. 15 (8), P = 0.8). Similary, no differences between both groups were found for CCI (normal FMD: 21 (30) (median (IQR)), reduced FMD: 26 (38), P = 0.4) or frequency of major complications (normal FMD: 7 (19%) (n (%)), reduced FMD: 12 (35%), P = 0.12). The regression analyses revealed that FMD in combination with ASA status and surgery duration had no additional significant predictive effect for DAH30, CCI or Clavien-Dindo score.

Conclusion

FMD does not add predictive value with regards to DAH30, CCI or Clavien-Dindo score within our study cohort of patients undergoing abdominal surgery.

Trial registration

The study was registered in the German Clinical Trials Register (DRKS00005472), prospectively registered on 25/11/2013.

Dysfunction of the Glymphatic System as a Potential Mechanism of Perioperative Neurocognitive Disorders

Perioperative neurocognitive disorder (PND) frequently occurs in the elderly as a severe postoperative complication and is characterized by a decline in cognitive function that impairs memory, attention, and other cognitive domains. Currently, the exact pathogenic mechanism of PND is multifaceted and remains unclear. The glymphatic system is a newly discovered glial-dependent perivascular network that subserves a pseudo-lymphatic function in the brain. Recent studies have highlighted the significant role of the glymphatic system in the removal of harmful metabolites in the brain. Dysfunction of the glymphatic system can reduce metabolic waste removal, leading to neuroinflammation and neurological disorders. We speculate that there is a causal relationship between the glymphatic system and symptomatic progression in PND. This paper reviews the current literature on the glymphatic system and some perioperative factors to discuss the role of the glymphatic system in PND.

Asymmetric dimethylarginine predicts perioperative cardiovascular complications in patients undergoing medium-to-high risk non-cardiac surgery

Objectives

Perioperative cardiovascular events remain an important factor that affects surgery outcome. We assessed if asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthesis, predicts perioperative risk, and if pre-operative supplementation with L-arginine/L-citrulline improves the plasma L-arginine/ADMA ratio.

Methods

In this prospective study, planned thoracic and/or abdominal surgery patients were randomized to receive L-arginine/L-citrulline (5 g/day) or placebo 1 to 5 days before surgery. We measured perioperative plasma ADMA and L-arginine levels. The primary outcome was a 30-day combined cardiovascular endpoint.

Results

Among 269 patients, 23 (8.6%) experienced a major adverse cardiovascular event. ADMA and C-reactive protein were significantly associated with the incidence of cardiovascular complications in the multivariable-adjusted analysis. The L-arginine plasma concentration was significantly higher on the day of surgery with L-arginine/L-citrulline supplementation compared with placebo. In patients with high pre-operative ADMA, there was a non-significant trend towards reduced incidence of the primary endpoint with L-arginine/L-citrulline supplementation (six vs. nine events).

Conclusions

ADMA is a predictor of major adverse cardiovascular complications in the perioperative period for patients who are undergoing major abdominal and/or thoracic surgery. Supplementation with L-arginine/L-citrulline increased the L-arginine plasma concentration, enhanced the L-arginine/ADMA ratio, and induced a trend towards fewer perioperative events.

Altered microvascular reactivity assessed by near-infrared spectroscopy after hepato-pancreato-biliary surgery

Little is known about microcirculatory dysfunction following abdominal surgeries. This study aimed to evaluate changes in microvascular reactivity (MVR) before and after major abdominal surgery, assessed by near-infrared spectroscopy in conjunction with a vascular occlusion test. This prospective observational study included 50 adult patients who underwent hepato-pancreato-biliary surgery lasting ≥ 8 h. MVR was assessed by tissue oxygen saturation (StO₂) changes in the plantar region of the foot during 3 min of vascular occlusion and subsequent release under general anesthesia before and after surgery. The primary outcome was alteration in the recovery slope of StO₂ (RecStO₂) and recovery time (tM) between the preoperative and postoperative values. Postoperative short-term outcome was represented by the Post-operative Morbidity Survey (POMS) score on the morning of postoperative day 2. After surgery, RecStO₂ was reduced (0.74% [0.58-1.06]/s vs. 0.89% [0.62-1.41]/s, P = 0.001), and tM was longer (57.0 [42.9-71.0] s vs. 41.3 [35.5-56.5] s, P < 0.001), compared to the preoperative values. Macrohemodynamic variables such as cardiac index, arterial pressure, and stroke volume during postoperative measurement did not differ with or without relative MVR decline. In addition, the POMS score was not associated with postoperative alterations in microcirculatory responsiveness. MVR in the plantar region of the foot was reduced after major hepato-pancreato-biliary surgery regardless of macrocirculatory adequacy. Impaired MVR was not associated with short-term outcomes as long as macrocirculatory indices were well maintained. The impact of relative microcirculatory changes, especially combined with inadequate macrocirculation, on postoperative complications remains to be elucidated.Clinical Trial Registrations UMIN-CTR trial ID: 000033461.

Patients with aortic stenosis exhibit early improved endothelial function following transcatheter aortic valve replacement: The eFAST study

BACKGROUND

Patients with severe aortic stenosis (AS) exhibit systemic endothelial dysfunction, which can be associated with myocardial ischaemia in absence of obstructive coronary disease. Transcatheter aortic valve replacement (TAVR) is used to treat severe AS in patients with high or prohibitive surgical risk. However, it remains unknown whether endothelial function recovers post-TAVR. We therefore sought to assess the early and late changes in flow-mediated dilation (FMD), a measure of endothelial function, following TAVR.

METHODS

Patients undergoing TAVR for severe AS had ultrasound assessment of brachial endothelial-independent and -dependent FMD. Measurements were performed pre-TAVR, at early follow-up (<48 h post-TAVR) and late follow-up (4-6 weeks post-TAVR).

RESULTS

27 patients (mean age 82.0 ± 7.0; 33.3% female) were recruited; 37.0% had diabetes mellitus and 59.3% had hypertension. Brachial artery FMD increased from 4.2 ± 1.6% (pre-TAVR) to 9.7 ± 3.5% at early follow-up (p < 0.0001). At late follow-up, improvement compared with early follow-up was sustained (8.7 ± 1.9%, p = 0.27). Resting brachial arterial flow velocities decreased significantly at late follow-up (11.24 ± 5.16 vs. 7.73 ± 2.79 cm/s, p = 0.003). Concordantly, at late follow-up, there was decrease in resting wall shear stress (WSS; 14.8 ± 7.8 vs. 10.6 ± 4.8dyne/cm2, p = 0.01), peak WSS (73.1 ± 34.1 vs. 58.8 ± 27.8dyne/cm2, p = 0.03) and cumulative WSS (3543 ± 1852 vs. 2504 ± 1089dyne·s/cm², p = 0.002). Additionally, a favourable inverse correlation between cumulative WSS and FMD was restored at late follow-up (r = -0.21 vs. r = 0.49).

CONCLUSION

Endothelial function in patients with AS improves early post-TAVR and this improvement is sustained. This likely occurs as a result of improved arterial haemodynamics, leading to lower localised WSS and release of vasoactive mediators that may also alleviate myocardial ischaemia.

Effect of remote ischaemic preconditioning on mortality and morbidity after non-cardiac surgery: meta-analysis

BACKGROUND

Remote ischaemic preconditioning (RIPC) has been shown to have a protective role on vital organs exposed to reperfusion injury. The aim of this systematic review was to evaluate the effects of non-invasive RIPC on clinical and biochemical outcomes in patients undergoing non-cardiac surgery.

METHODS

A systematic literature search of PubMed, EMBASE, Scopus, and Cochrane databases was carried out in February 2020. RCTs investigating the effect of non-invasive RIPC in adults undergoing non-cardiac surgery were included. Meta-analyses and trial sequential analyses (TSAs) were performed on cardiovascular events, acute kidney injury, and short- and long-term mortality.

RESULTS

Some 43 RCTs including 3660 patients were included. The surgical areas comprised orthopaedic, vascular, abdominal, pulmonary, neurological, and urological surgery. Meta-analysis showed RIPC to be associated with fewer cardiovascular events in non-cardiac surgery (13 trials, 1968 patients, 421 events; odds ratio (OR) 0.68, 95 per cent c.i. 0.47 to 0.96; P = 0.03). Meta-analyses of the effect of RIPC on acute kidney injury (12 trials, 1208 patients, 211 events; OR 1.14, 0.78 to 1.69; P = 0.50; I2 = 9 per cent), short-term mortality (7 trials, 1239 patients, 65 events; OR 0.65, 0.37 to 1.12; P = 0.12; I2 = 0 per cent), and long-term mortality (4 trials, 1167 patients, 9 events; OR 0.67, 0.18 to 2.55; P = 0.56; I2 = 0 per cent) showed no significant differences for RIPC compared with standard perioperative care in non-cardiac surgery. However, TSAs showed that the required information sizes have not yet been reached.

CONCLUSION

Application of RIPC to non-cardiac surgery might reduce cardiovascular events, but not acute kidney injury or all-cause mortality, but currently available data are inadequate to confirm or reject an assumed intervention effect.

The effect of remote ischaemic preconditioning on endothelial function after hip fracture surgery

BACKGROUND

Endothelial dysfunction seems to play a role in the pathophysiology of myocardial injury after surgery. The aim of this randomised clinical trial was to examine whether remote ischaemic preconditioning in relation to hip fracture surgery ameliorates post-operative systemic endothelial dysfunction.

METHODS

This was a planned single-centre pilot sub-study of a multicentre, randomised clinical trial. Patients ≥45 years with a cardiovascular risk factor were randomised to remote ischaemic preconditioning (RIPC) or control (standard treatment) performed in relation with their hip fracture operation. RIPC consisted of four cycles of 5 minutes forearm ischaemia and reperfusion. The procedure was performed non-invasively with a tourniquet. The endothelial function was assessed with non-invasive digital pulse amplitude tonometry on post-operative day 1 and expressed as the reactive hyperaemia index (RHI). Endothelial dysfunction was defined as RHI < 1.22.

RESULTS

Between February 2015 and December 2016, 18 patients were allocated to the RIPC group and 20 patients to the control group. The endothelial function was impaired in both groups on post-operative day 1. RHI did not differ between the groups, 1.47 (95% CI 1.20-1.75) in the RIPC group vs. 1.54 (95% CI 1.17-1.91) in the control group, P = .76. Endothelial dysfunction was present in 3/18 patients (16.7%) in the RIPC group and 8/20 patients (40%) in the control group, P = .11.

CONCLUSION

No beneficial effect of remote ischaemic preconditioning on the systemic endothelial dysfunction, assessed at a single time point on post-operative day one, was detected after hip fracture surgery.

The risk of post-operative myocardial injury after major emergency abdominal surgery: A retrospective cohort study

BACKGROUND

The aim was to examine the risk of post-operative myocardial injury after major emergency abdominal surgery and identify pre- and intra-operative risk factors of post-operative myocardial injury. Moreover, the study aimed to examine the association between post-operative myocardial injury and clinical outcomes.

METHODS

This was a retrospective cohort study including patients undergoing major emergency abdominal surgery from February 2017 to January 2019. Troponin I was assessed on post-operative days 1-3. Post-operative myocardial injury was defined as a cardiac troponin I ≥ 45 ng per litre. Post-operative clinical outcomes included in-hospital myocardial infarction, in-hospital major adverse cardiovascular events, reoperation, admission to the intensive care unit, lengths of stay, 30- and 90-day all-cause mortality.

RESULTS

98 out of 401 patients (24.4%) sustained a post-operative myocardial injury within the third post-operative day. Increasing age was an independent risk factor of post-operative myocardial injury (age per 10 years adjusted odds ratio 2.2 [95% CI 1.7-2.9], P < .0001). Patients with post-operative myocardial injury had an increased risk of major adverse cardiovascular events, a higher admission rate to the intensive care unit, a longer median post-operative length of stay and a higher 30- and 90-day all-cause mortality compared with patients without myocardial injury.

CONCLUSION

One in four patients suffered a post-operative myocardial injury within the third post-operative day. Post-operative myocardial injury was a risk factor of adverse cardiac and non-cardiac clinical outcomes. Troponin monitoring could potentially improve the post-operative risk stratification in this cohort of high-risk surgical patients.

Trauma of major surgery: A global problem that is not going away

Globally, a staggering 310 million major surgeries are performed each year; around 40 to 50 million in USA and 20 million in Europe. It is estimated that 1-4% of these patients will die, up to 15% will have serious postoperative morbidity, and 5-15% will be readmitted within 30 days. An annual global mortality of around 8 million patients places major surgery comparable with the leading causes of death from cardiovascular disease and stroke, cancer and injury. If surgical complications were classified as a pandemic, like HIV/AIDS or coronavirus (COVID-19), developed countries would work together and devise an immediate action plan and allocate resources to address it. Seeking to reduce preventable deaths and post-surgical complications would save billions of dollars in healthcare costs. Part of the global problem resides in differences in institutional practice patterns in high- and low-income countries, and part from a lack of effective perioperative drug therapies to protect the patient from surgical stress. We briefly review the history of surgical stress and provide a path forward from a systems-based approach. Key to progress is recognizing that the anesthetized brain is still physiologically 'awake' and responsive to the sterile stressors of surgery. New intravenous drug therapies are urgently required after anesthesia and before the first incision to prevent the brain from switching to sympathetic overdrive and activating secondary injury progression such as hyperinflammation, coagulopathy, immune activation and metabolic dysfunction. A systems-based approach targeting central nervous system-mitochondrial coupling may help drive research to improve outcomes following major surgery in civilian and military medicine.

Intravenous lidocaine to prevent endothelial dysfunction after major abdominal surgery: a randomized controlled pilot trial

Background

Major abdominal surgery is associated with endothelial glycocalyx disruption. The anti-inflammatory effects of lidocaine were recently associated with endothelial barrier protection.

Methods

This was a single-centre, parallel group, randomized, controlled, double blind, pilot trial. Forty adult patients scheduled for major abdominal surgery were included between December 2016 and March 2017 in the setting of a University Hospital in Brussels (Belgium); reasons for non-inclusion were planned liver resection and conditions associated to increased risk of local anesthetics systemic toxicity. Patients were randomized to receive either lidocaine by continuous intravenous administration or an equivalent volume of 0.9% saline.

The primary endpoint was the postoperative syndecan-1 concentration (difference between groups). Near-infrared spectroscopy of the thenar eminence in association with the vascular occlusion test, and contemporary analysis of flow-mediated dilation of the brachial artery were the secondary outcomes, along with haemodynamic data. Blood samples and data were collected before surgery (T0), and at 1–3 h (T1) and 24 h (T2) post-surgery.

Results

Syndecan-1 concentration increased significantly post-surgery (P < 0.001), but without any difference between groups. The near-infrared spectroscopy-derived and flow-mediated dilation-derived variables showed minor changes unrelated to group assignment. Compared with the placebo group, the intervention group had a significantly lower peri-operative mean arterial pressure and cardiac index, despite equally conducted goal-directed haemodynamic management. Postoperative lactate concentrations were similar between groups.

Conclusions

Lidocaine failed to have any effect on endothelial function. Since in comparisons to other types of clinical situations, syndecan-1 was only slightly upregulated, endothelial dysfunction after major abdominal surgery might be overestimated.

Trial registration

« ISRCTN Registry » identifier: ISRCTN63417725. Date: 15/06/2020. Retrospectively registered.

Endothelial dysfunction and myocardial injury after major emergency abdominal surgery: a prospective cohort study

Background

Preoperative endothelial dysfunction is a predictor of myocardial injury and major adverse cardiac events. Non-cardiac surgery is known to induce acute endothelial changes. The aim of this explorative cohort study was to assess the extent of systemic endothelial dysfunction after major emergency abdominal surgery and the potential association with postoperative myocardial injury.

Methods

Patients undergoing major emergency abdominal surgery were included in this prospective cohort study. The primary outcome was the change in endothelial function expressed as the reactive hyperemia index from 4-24 h after surgery until postoperative day 3–5. The reactive hyperemia index was assessed by non-invasive digital pulse tonometry. Secondary outcomes included changes in biomarkers of nitric oxide metabolism and bioavailability. All assessments were performed at the two separate time points in the postoperative period. Clinical outcomes included myocardial injury within the third postoperative day and major adverse cardiovascular events within 30 days of surgery.

Results

Between October 2016 and June 2017, 83 patients were included. The first assessment of the endothelial function, 4–24 h, was performed 15.8 (SD 6.9) hours after surgery and the second assessment, postoperative day 3–5, was performed 83.7 (SD 19.8) hours after surgery. The reactive hyperemia index was suppressed early after surgery and did not increase significantly; 1.64 (95% CI 1.52–177) at 4–24 h after surgery vs. 1.75 (95% CI 1.63–1.89) at postoperative day 3–5, p = 0.34. The L-arginine/ADMA ratio, expressing the nitric oxide production, was reduced in the perioperative period and correlated significantly with the reactive hyperemia index. A total of 16 patients (19.3%) had a major adverse cardiovascular event, of which 11 patients (13.3%) had myocardial injury. The L-arginine/ADMA ratio was significantly decreased at 4–24 h after surgery in patients suffering myocardial injury.

Conclusion

This explorative pathophysiological study showed that acute systemic endothelial dysfunction was present early after major emergency abdominal surgery and remained unchanged until day 3–5 after the procedure. Early postoperative disturbances in the nitric oxide bioavailability might add to the pathogenesis of myocardial injury. This pathophysiological link should be confirmed in larger studies.

Trial registration

clinicaltrials.gov no. NCT03010969.

The effect of remote ischaemic preconditioning on myocardial injury in emergency hip fracture surgery (PIXIE trial): phase II randomised clinical trial

OBJECTIVE

To investigate whether remote ischaemic preconditioning (RIPC) prevents myocardial injury in patients undergoing hip fracture surgery.

DESIGN

Phase II, multicentre, randomised, observer blinded, clinical trial.

SETTING

Three Danish university hospitals, 2015-17.

PARTICIPANTS

648 patients with cardiovascular risk factors undergoing hip fracture surgery. 286 patients were assigned to RIPC and 287 were assigned to standard practice (control group).

INTERVENTION

The RIPC procedure was initiated before surgery with a tourniquet applied to the upper arm and consisted of four cycles of forearm ischaemia for five minutes followed by reperfusion for five minutes.

MAIN OUTCOME MEASURES

The original primary outcome was myocardial injury within four days of surgery, defined as a peak plasma cardiac troponin I concentration of 45 ng/L or more caused by ischaemia. The revised primary outcome was myocardial injury within four days of surgery, defined as a peak plasma cardiac troponin I concentration of 45 ng/L or more or high sensitive troponin I greater than 24 ng/L (the primary outcome was changed owing to availability of testing). Secondary outcomes were peak plasma troponin I and total troponin I release during the first four days after surgery (cardiac and high sensitive troponin I), perioperative myocardial infarction, major adverse cardiovascular events, and all cause mortality within 30 days of surgery, length of postoperative stay, and length of stay in the intensive care unit. Several planned secondary outcomes will be reported elsewhere.

RESULTS

573 of the 648 randomised patients were included in the intention-to-treat analysis (mean age 79 (SD 10) years; 399 (70%) women). The primary outcome occurred in 25 of 168 (15%) patients in the RIPC group and 45 of 158 (28%) in the control group (odds ratio 0.44, 95% confidence interval 0.25 to 0.76; P=0.003). The revised primary outcome occurred in 57 of 286 patients (20%) in the RIPC group and 90 of 287 (31%) in the control group (0.55, 0.37 to 0.80; P=0.002). Myocardial infarction occurred in 10 patients (3%) in the RIPC group and 21 patients (7%) in the control group (0.46, 0.21 to 0.99; P=0.04). Statistical power was insufficient to draw firm conclusions on differences between groups for the other clinical secondary outcomes (major adverse cardiovascular events, 30 day all cause mortality, length of postoperative stay, and length of stay in the intensive care unit).

CONCLUSIONS

RIPC reduced the risk of myocardial injury and infarction after emergency hip fracture surgery. It cannot be concluded that RIPC overall prevents major adverse cardiovascular events after surgery. The findings support larger scale clinical trials to assess longer term clinical outcomes and mortality.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02344797.

Atorvastatin and Vitamin E Accelerates NASH Resolution by Dietary Intervention in a Preclinical Guinea Pig Model

Despite affecting millions of patients worldwide, no pharmacological treatment has yet proved effective against non-alcoholic steatohepatitis (NASH) induced liver fibrosis. Current guidelines recommend lifestyle modifications including reductions in dietary energy intake. Recently, therapy with atorvastatin and vitamin E (vitE) has been recommended, although clinical studies on the resolution of hepatic fibrosis are inconclusive. Targeting NASH-induced hepatic end-points, this study evaluated the effects of atorvastatin and vitE alone or in combination with a dietary intervention in the guinea pig NASH model. Guinea pigs (n = 72) received 20 weeks of high fat feeding before allocating to four groups: continued HF feeding (HF), HF diet with atorvastatin and vitE (HF+), low-fat diet (LF) and low-fat with atorvastatin and vitE (LF+), for four or eight weeks of intervention. Both LF and LF+ decreased liver weight, cholesterol and plasma dyslipidemia. LF+ further improved hepatic histopathological hallmarks (p < 0.05), liver injury markers aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (p < 0.05) and reduced the expression of target genes of hepatic inflammation and fibrosis (p < 0.05), underlining an increased effect on NASH resolution in this group. Collectively, the data support an overall beneficial effect of diet change, and indicate that atorvastatin and vitE therapy combined with a diet change act synergistically in improving NASH-induced endpoints.

The Effect of Nitric Oxide on Remote Ischemic Preconditioning in Renal Ischemia Reperfusion Injury in Rats

Although remote ischemic preconditioning (RIPC) is an organ-protective maneuver from subsequent ischemia reperfusion injury (IRI) by application of brief ischemia and reperfusion to other organs, its mechanism remains unclear. However, it is known that RIPC reduces the heart, brain, and liver IRI, and that nitric oxide (NO) is involved in the mechanism of this effect. To identify the role of NO in the protective effect of RIPC in renal IRI, this study examined renal function, oxidative status, and histopathological changes using N-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor. Remote ischemic preconditioning was produced by 3 cycles of 5 minutes ischemia and 5 minutes reperfusion. Blood urea nitrogen, creatinine (Cr), and renal tissue malondialdehyde levels were lower, histopathological damage was less severe, and superoxide dismutase level was higher in the RIPC + IRI group than in the IRI group. The renoprotective effect was reversed by L-NAME. Obtained results suggest that RIPC before renal IRI contributes to improvement of renal function, increases antioxidative marker levels, and decreases oxidative stress marker levels and histopathological damage. Moreover, NO is likely to play an important role in this protective effect of RIPC on renal IRI.

Utility of the cold pressor test to predict future cardiovascular events

INTRODUCTION

The cold pressor test (CPT) is a common and extensively validated test, which induces systemic stress involving immersion of an individual's hand in ice water (normally temperature between 0 and 5 degrees Celsius) for a period of time. CPT has been used in various fields, like examining effects of stress on memory, decision-making, pain and cardiovascular health. Areas covered: In terms of cardiovascular health, current research is mainly interested in predicting the occurrence of cardiovascular (CV) events. The objective of this review is to give an overview of the history and methodology of the CPT, and clinical utility in possibly predicting CV events in CAD and other atherosclerotic diseases. Secondly, we will discuss possible future applications of the CPT in clinical care. Expert opinion: An important issue to address is the fact that the physiology of the CPT is not fully understood at this moment. As pointed out multiple mechanisms might be responsible for contributing to either coronary vasodilatation or coronary vasoconstriction. Regarding the physiological mechanism of the CPT and its effect on the measurements of the carotid artery reactivity even less is known.

Risk of ischemic stroke after discharge from inpatient surgery: Does the type of surgery matter?

OBJECTIVE

Stroke is a well-known and devastating complication during the perioperative period. However, detailed stroke risk profiles within 90 days in patients discharged without stroke after inpatient surgery are not fully understood. Using the case-crossover design, we aimed to evaluate the risk of ischemic stroke in these patients.

METHODS

We included adult patients with the first hospitalization for ischemic stroke between 2011 and 2012 from 23 million enrollees in the National Health Insurance Research Database. Admission date of the hospitalization was defined as the case day and exactly 365 days before the admission date as the control day. The exposure was the last hospitalization for surgery within 1-30, 31-60, or 61-90 days (case period) before the case day or similar time intervals (control period) before the control day. Surgical types were grouped based on the International Classification of Diseases procedure codes. We performed conditional logistic regression adjusting for time-varying variables to determine the relationship between surgery and subsequent stroke, and case-time-control analyses to examine whether the results were confounded by the time-trend in surgery.

RESULTS

A total of 56596 adult patients (41% female, mean age 69 years) comprised the study population. After adjustment was made for confounding variables, an association between stroke and prior inpatient surgery within 30 days was observed (adjusted odds ratio 1.44; 95% confidence interval 1.29-1.61). Cardiothoracic, vascular, digestive surgery, and musculoskeletal surgery within 30 days independently predicted ischemic stroke in the case-crossover analysis. In the case-time-control analysis, inpatient surgery remained an independent risk factor for ischemic stroke, whereas only cardiothoracic, vascular, and digestive surgery independently predicted ischemic stroke.

CONCLUSIONS

Surgery as a whole independently increased the risk of ischemic stroke within 30 days. Among various types of surgery, cardiothoracic, vascular, and digestive surgery significantly increased the risk of ischemic stroke.

Cardiorespiratory fitness is impaired and predicts mid-term postoperative survival in patients with abdominal aortic aneurysm disease

NEW FINDINGS

What is the central question of this study? To what extent cardiorespiratory fitness is impaired in patients with abdominal aortic aneurysmal (AAA) disease and corresponding implications for postoperative survival requires further investigation. What is the main finding and its importance? Cardiorespiratory fitness is impaired in patients with AAA disease. Patients with peak oxygen uptake of <13.1 ml O₂  kg^-1  min^-1 and ventilatory equivalent for carbon dioxide at anaerobic threshold ≥34 are associated with increased risk of postoperative mortality at 2 years. These findings demonstrate that cardiorespiratory fitness can predict mid-term postoperative survival in AAA patients, which may help to direct care provision.

ABSTRACT

Preoperative cardiopulmonary exercise testing is a standard assessment of cardiorespiratory fitness (CRF) and risk stratification. However, to what extent CRF is impaired in patients undergoing surgical repair of abdominal aortic aneurysm (AAA) disease and the corresponding implications for postoperative outcome requires further investigation. We measured CRF during an incremental exercise test to exhaustion using online respiratory gas analysis in patients with AAA disease (n = 124, aged 72 ± 7 years) and healthy sedentary control subjects (n = 104, aged 70 ± 7 years). Postoperative survival was examined for association with CRF, and threshold values were calculated for independent predictors of mortality. Patients who underwent preoperative cardiopulmonary exercise testing before surgical repair had lower CRF [age-adjusted mean difference of 12.5 ml O₂  kg^-1  min^-1 for peak oxygen uptake ( V ̇ O 2 peak ), P < 0.001 versus control subjects]. After multivariable analysis, both V ̇ O 2 peak and the ventilatory equivalent for carbon dioxide at anaerobic threshold ( V ̇ E / V ̇ C O 2 - AT ) were independent predictors of mid-term postoperative survival (2 years). Hazard ratios of 5.27 (95% confidence interval 1.62-17.14, P = 0.006) and 3.26 (95% confidence interval 1.00-10.59, P = 0.049) were observed for V ̇ O 2 peak  < 13.1 ml O₂  kg^-1  min^-1 and V ̇ E / V ̇ C O 2 - AT ≥ 34, respectively. Thus, CRF is lower in patients with AAA, and those with a V ̇ O 2 peak  < 13.1 ml O₂  kg^-1  min^-1 and V ̇ E / V ̇ C O 2 - AT ≥ 34 are associated with a markedly increased risk of postoperative mortality. Collectively, our findings demonstrate that CRF can predict mid-term postoperative survival in AAA patients, which may help to direct care provision.

Liraglutide Decreases Hepatic Inflammation and Injury in Advanced Lean Non-Alcoholic Steatohepatitis

Although commonly associated with obesity, non-alcoholic fatty liver disease (NAFLD) is also present in the lean population representing a unique disease phenotype. Affecting 25% of the world's population, NAFLD is associated with increased mortality especially when progressed to non-alcoholic steatohepatitis (NASH). However, no approved pharmacological treatments exist. Current research focuses mainly on NASH associated with obesity, leaving the effectiveness of promising treatments in lean NASH virtually unknown. This study therefore aimed to evaluate the effect of liraglutide (glucagon-like peptide 1 analogue) and dietary intervention, alone and in combination, in guinea pigs with non-obese NASH. After 20 weeks of high-fat feeding (20% fat, 15% sucrose, 0.35% cholesterol), 40 female guinea pigs were block-randomized based on weight into four groups receiving one of four treatments for 4 weeks: continued high-fat diet (HF, control), high-fat diet and liraglutide treatment (HFL), chow diet (4% fat, 0% sucrose, 0% cholesterol; HFC) or chow diet and liraglutide treatment (HFCL). High-fat feeding induced NASH with severe fibrosis. Liraglutide decreased inflammation (p < 0.05) and hepatocyte ballooning (p < 0.05), while increasing hepatic α-tocopherol (p = 0.0154). Dietary intervention did not improve liver histopathology significantly, but decreased liver weight (p = 0.004), plasma total cholesterol (p = 0.0175), LDL-cholesterol (p = 0.0063), VLDL-cholesterol (p = 0.0034), hepatic cholesterol (p < 0.0001) and increased hepatic vitamin C (p = 0.0099). Combined liraglutide and dietary intervention induced a rapid weight loss, necessitating periodical liraglutide dose adjustment/discontinuation, limiting the strength of the findings from this group. Collectively, this pre-clinical study supports the beneficial effect of liraglutide on NASH and extends this notion to lean NASH.

Vasomotor function in rat arteries after ex vivo and intragastric exposure to food-grade titanium dioxide and vegetable carbon particles

Background

Humans are continuously exposed to particles in the gastrointestinal tract. Exposure may occur directly through ingestion of particles via food or indirectly by removal of inhaled material from the airways by the mucociliary clearance system. We examined the effects of food-grade particle exposure on vasomotor function and systemic oxidative stress in an ex vivo study and intragastrically exposed rats.

Methods

In an ex vivo study, aorta rings from naïve Sprague-Dawley rats were exposed for 30 min to food-grade TiO₂ (E171), benchmark TiO₂ (Aeroxide P25), food-grade vegetable carbon (E153) or benchmark carbon black (Printex 90). Subsequently, the vasomotor function was assessed in wire myographs. In an in vivo study, lean Zucker rats were exposed intragastrically once a week for 10 weeks to vehicle, E171 or E153. Doses were comparable to human daily intake. Vasomotor function in the coronary arteries and aorta was assessed using wire myographs. Tetrahydrobiopterin, ascorbate, malondialdehyde and asymmetric dimethylarginine were measured in blood as markers of oxidative stress and vascular function.

Results

Direct exposure of E171 to aorta rings ex vivo increased the acetylcholine-induced vasorelaxation and 5-hydroxytryptamine-induced vasocontraction. E153 only increased acetylcholine-induced vasorelaxation, and Printex 90 increased the 5-hydroxytryptamine-induced vasocontraction, whereas Aeroxide P25 did not affect the vasomotor function. In vivo exposure showed similar results as ex vivo exposure; increased acetylcholine-induced vasorelaxation in coronary artery segments of E153 and E171 exposed rats, whereas E171 exposure altered 5-hydroxytryptamine-induced vasocontraction in distal coronary artery segments. Plasma levels of markers of oxidative stress and vascular function showed no differences between groups.

Conclusion

Gastrointestinal tract exposure to E171 and E153 was associated with modest albeit statistically significant alterations in the vasocontraction and vasorelaxation responses. Direct particle exposure to aorta rings elicited a similar type of response. The vasomotor responses were not related to biomarkers of systemic oxidative stress.