Validation of long-term survival prediction for scheduled abdominal aortic aneurysm repair with an independent calculator using only pre-operative variables

Ventilatory efficiency as a prognostic factor for postoperative complications in patients undergoing elective major surgery: a systematic review

BACKGROUND

Major surgery is associated with high complication rates. Several risk scores exist to assess individual patient risk before surgery but have limited precision. Novel prognostic factors can be included as additional building blocks in existing prediction models. A candidate prognostic factor, measured by cardiopulmonary exercise testing, is ventilatory efficiency (VE/VCO2). The aim of this systematic review was to summarise evidence regarding VE/VCO2 as a prognostic factor for postoperative complications in patients undergoing major surgery.

METHODS

A medical library specialist developed the search strategy. No database-provided limits, considering study types, languages, publication years, or any other formal criteria were applied to any of the sources. Two reviewers assessed eligibility of each record and rated risk of bias in included studies.

RESULTS

From 10,082 screened records, 65 studies were identified as eligible. We extracted adjusted associations from 32 studies and unadjusted from 33 studies. Risk of bias was a concern in the domains 'study confounding' and 'statistical analysis'. VE/VCO2 was reported as a prognostic factor for short-term complications after thoracic and abdominal surgery. VE/VCO2 was also reported as a prognostic factor for mid- to long-term mortality. Data-driven covariable selection was applied in 31 studies. Eighteen studies excluded VE/VCO2 from the final multivariable regression owing to data-driven model-building approaches.

CONCLUSIONS

This systematic review identifies VE/VCO2 as a predictor for short-term complications after thoracic and abdominal surgery. However, the available data do not allow conclusions about clinical decision-making. Future studies should select covariables for adjustment a priori based on external knowledge.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42022369944).

Association of polypharmacy scores with the long-term survival of patients with intact aortoiliac aneurysms and indication for repair

OBJECTIVE/BACKGROUND

Our study analyzed the relationship between two polypharmacy scores (addition of chronic prescribed drugs [ACPDs] and Rx-Risk Comorbidity Index) and survival in patients with an intact abdominal aortic and/or common iliac aneurysm (AAA).

METHODS

Consecutive retrospective, single-center cohort of patients attended for an intact AAA with indication for repair from 2008 to 2021. Demographic data, Charlson Comorbidity Index, AAA treatment, ACPD, and Rx-Risk polypharmacy scores were recorded at baseline. Main outcomes were the 5-year and long-term survival rates. The statistical analysis included Cox regression, area under the curve, and continuous net reclassification index.

RESULTS

A total of 424 patients with AAA were evaluated (median age: 76 years; 92.2% male, median Charlson index 2), of whom 314 (74.1%) underwent intervention (80% endovascular and 20% open) and 110 (25.9%) did not. During follow-up (mean 4.6 years), 245 patients (57.8%) died, with 1-month, 1-year, and 5-year survival rates of 98.1%, 86.3%, and 52.7%, respectively. ACPD and Rx-Risk indices (median [interquartile range]: 6 [4-9] and 3 [0-5], respectively) were significantly and linearly associated (P < .001) with survival, with the best cutoff points at 5 and 0, respectively. An ACPD >5 (patients with >5 chronically prescribed drugs at baseline) and an Rx-Risk >0 were associated with a 45.2% (P = .038) and 102% (P = .002) increase in 5-year mortality, respectively, after adjustment for age, sex, Charlson index, and type of AAA treatment. Both polypharmacy indices improved significantly the discriminative power of the Charlson Comorbidity Index in predicting survival.

CONCLUSIONS

Both ACPD and Rx-Risk polypharmacy scores are independently related to survival among patients with an intact AAA and indication for repair. Their behavior is similar, so the simple ACPD >5 appears to be sufficient to identify patients with lower survival rates.

Sex-related differences in functional capacity and its implications in risk stratification before major non-cardiac surgery: a post hoc analysis of the international METS study

Background

Poor functional capacity has been identified as an important modifiable risk factor for postoperative complications. Cardiopulmonary exercise testing (CPET) provides objective parameters of functional capacity (e.g., oxygen consumption at peak exercise, peak VO2), with significant prognostication for postoperative complications. However, sex-specific thresholds for functional capacity to predict surgical risk are yet to be established. Therefore, we performed a post hoc analysis of the international, multicentre, prospective observational METS (Measurement of Exercise Tolerance before Surgery) study to evaluate if sex-specific thresholds of peak VO2 improve risk prediction of postoperative complications.

Methods

We undertook a post hoc analysis (HREC/71824/PMCC) of the METS study, which was performed between March 2013 and March 2016. We investigated whether sex-specific differences exist for CPET-derived parameters and associated thresholds for predicting postoperative complications in this large cohort of patients that had major non-cardiac surgery (n = 1266). Logistic regression models were analyzed for the association of low peak VO2 with moderate-to-severe in-hospital postoperative complications. Optimal sex-specific peak VO2 thresholds were obtained by maximizing the Youden index of receiver operating characteristic (ROC) curves. Finally, multivariable logistic regression models tested the resulting sex-specific thresholds against the established non-sex-specific peak VO2 threshold (14 mL kg-1 min-1) adjusted for clinically relevant features such as comorbidities and surgical complexity. Models were evaluated by bootstrapping optimism-corrected area under the ROC curve and the net reclassification improvement index (NRI).

Findings

Female patients (n = 480) had a lower mean (SD) peak VO2 than males (16.7 (4.9) mL kg-1 min-1 versus 21.2 (6.5) mL kg-1 min-1, p < 0.001) and a lower postoperative complication rate (10.4% versus 15.3%; p = 0.018) than males (n = 786). The optimal peak VO2 threshold for predicting postoperative complications was 12.4 mL kg-1 min-1 for females and 22.3 mL kg-1 min-1 for males, respectively. In the multivariable regression model, low non-sex-specific peak VO2 did not independently predict postoperative complications. In contrast, low sex-specific peak VO2 was an independent predictor of postoperative complications (OR 2.29; 95% CI: 1.60, 3.30; p < 0.001). The optimism-corrected AUC-ROC of the sex-specific model was higher compared with the non-sex-specific model (0.73 versus 0.7; DeLong's test: p = 0.021). The sex-specific model classified 39% of the patients more correctly than the baseline model (NRI = 0.39; 95% CI: 0.24, 0.55). In contrast, the non-sex-specific model only classified 9% of the patients more correctly when compared against the baseline model (NRI = 0.09; 95% CI: -0.04, 0.22).

Interpretation

Our data report sex-specific differences in preoperative CPET-derived functional capacity parameters. Sex-specific peak VO2 thresholds identify patients at increased risk for postoperative complications with a higher discriminatory ability than a sex-unspecific threshold. As such, sex-specific threshold values should be considered in preoperative CPET to potentially improve risk stratification and to guide surgical decision-making, including eligibility for surgery, preoperative optimization strategies (prehabilitation) or seeking non-surgical options.

Funding

There was no funding for the present study. The original METS study was funded by Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Ontario Ministry of Health and Long-Term Care, Ontario Ministry of Research, Innovation and Science, UK National Institute of Academic Anaesthesia, UK Clinical Research Collaboration, Australian and New Zealand College of Anaesthetists, and Monash University.

Preoperative assessment and optimisation prior to planned aortic aneurysm repair: a UK survey examining current practice and attitudes of vascular surgeons and vascular anaesthetists

BACKGROUND

The majority of those diagnosed with aortic aneurysm in the UK are older, multi-morbid patients. Decision-making as to who may benefit from intervention (open or endovascular aneurysm repair) is highly variable across the NHS (as is the mode of intervention), in part because there are no detailed guidelines or consensus on preoperative assessment. Thus, there is likely to be significant variation in the pre-operative assessment and optimisation of these patients.

METHODS

A survey was designed to understand current practice and attitudes of vascular surgeons and vascular anaesthetists in the UK regarding preoperative assessment and optimisation of patients undergoing elective aortic aneurysm repair. The survey was reviewed and validated by an expert panel, then distributed electronically to all vascular surgical and vascular anaesthetic leads in the UK.

RESULTS

Overall, the response rate was 68%. The responses were varied between surgeons and anaesthetists, with differences reported in the preoperative assessment and optimisation of patients, the approach to shared decision-making, and the perioperative pathway.

CONCLUSIONS

Despite initiatives such as Getting It Right First Time (GIRFT) and National Institute for Health and Care Excellence (NICE) guidelines, variation still exists between centres with some differences in opinion observed between surgeons and anaesthetists. These differences may be leading to duplication of work in the perioperative pathway, inconsistencies in how risk is assessed and communicated with consequent variation in patient care. Addressing these issues requires awareness and implementation of existing guidelines, transdisciplinary working, efficient data-driven pathways, and structured aortic aneurysm multi-disciplinary team to promote meaningful shared decision-making.

[The Status of Spiroergometry in Preoperative Risk Assessment]

Physical performance is considered as a prognostic factor for perioperative mortality and morbidity. Thus, in recent years, spiroergometry has gained increasing significance in preoperative assessment. Beside the measurement of functional capacity, spiroergometric results may yield indications for cardiocirculatory or pulmonary disorders. A significant increased risk profile is reflected in the values VO₂max < 15 ml/kg/min, VO₂ at the first ventilatory threshold (VT1) < 11 ml/kg/min, and VE/VCO₂ at VT1 > 34. Prior to the examination, contraindications should be taken into account and standardized conduction must be adhered to. Many studies substantiate the positive effect of prehabilitation on morbidity, quality of life, and length of hospitalization, in particular in abdominal, thoracic and hepatobiliary surgery. Using the data acquired in the performance diagnostic, an optimized individual training plan can be drawn up. Besides, the risk evaluation contributes to planning surgical and anaesthetic procedures. Regular training and interdisciplinary teamwork are of utmost importance for the correct interpretation and application of the partly rather complex results.

Prognostic model for survival of patients with abdominal aortic aneurysms treated with endovascular aneurysm repair

The role of endovascular aneurysm repair (EVAR) in patients with asymptomatic abdominal aortic aneurysm (AAA) who are unfit for open surgical repair has been questioned. The impending risk of aneurysm rupture, the risk of elective repair, and the life expectancy must be balanced when considering elective AAA repair. This retrospective observational cohort study included all consecutive patients treated with standard EVAR for AAA at a referral centre between 2001 and 2020. A previously published predictive model for survival after EVAR in patients treated between 2001 and 2012 was temporally validated using patients treated at the same institution between 2013 and 2020 and updated using the overall cohort. 558 patients (91.2% males, mean age 74.9 years) were included. Older age, lower eGFR, and COPD were independent predictors for impaired survival. A risk score showed good discrimination between four risk groups (Harrel's C = 0.70). The 5-years survival probabilities were only 40% in "high-risk" patients, 68% in "moderate-to-high-risk" patients, 83% in "low-to-moderate-risk", and 89% in "low-risk" patients. Low-risk patients with a favourable life expectancy are likely to benefit from EVAR, while high-risk patients with a short life expectancy may not benefit from EVAR at the current diameter threshold.

Subjective assessment underestimates surgical risk: On the potential benefits of cardiopulmonary exercise testing for open thoracoabdominal repair

Background

Initial clinical evaluation (ICE) is traditionally considered a useful screening tool to identify frail patients during the preoperative assessment. However, emerging evidence supports the more objective assessment of cardiorespiratory fitness (CRF) via cardiopulmonary exercise testing (CPET) to improve surgical risk stratification. Herein, we compared both subjective and objective assessment approaches to highlight the interpretive idiosyncrasies.

Methods

As part of routine preoperative patient contact, patients scheduled for major surgery were prospectively “eyeballed” (ICE) by two experienced clinicians before more detailed history taking that also included the American Society of Anesthesiologists score classification. Each patient was subjectively judged to be either “frail” or “not frail” by ICE and “fit” or “unfit” from a thorough review of the medical notes. Subjective data were compared against the more objective validated assessment of postoperative outcomes using established CPET “cut‐off” metrics incorporating peak pulmonary oxygen uptake, V̇O_2PEAK at the anaerobic threshold (V̇O₂‐AT), and ventilatory equivalent for carbon dioxide that collectively informed risk stratification. These data were retrospectively extracted from a single‐center prospective National Health Service database. Data were analyzed using the Chi‐square automatic interaction detection decision tree method.

Results

A total of 127 patients were examined that comprised 58% male and 42% female patients aged 69 ± 10 years with a body mass index of 29 ± 7 kg/m². Patients were poorly conditioned with a V̇O_2PEAK almost 20% lower than predicted for age, sex‐matched healthy controls with 35% exhibiting a V̇O₂‐AT < 11 ml/kg/min. Disagreement existed between the subjective assessments of risk with ∼34% of patients classified as not frail on ICE were considered unfit by notes review (p < .0001). Furthermore, ∼35% of patients considered not frail on ICE and ∼31% of patients considered fit by notes review exhibited a V̇O₂‐AT < 11 ml/kg/min, and of these, ∼28% and ∼19% were classified as intermediate to high risk.

Conclusions

These findings highlight the interpretive limitations associated with the subjective assessment of patient frailty with surgical risk classification underestimated in up to a third of patients compared to the validated assessment of CRF. They reinforce the benefits of a more objective and integrated approach offered by CPET that may help us to improve perioperative risk assessment and better direct critical care provision in patients scheduled for “high‐stakes” surgery including open thoracoabdominal aortic aneurysm repair.

Anaesthesia for Hepatic Resection Surgery

This article will focus on the perioperative management of hepatic resection for colorectal cancer (CRC) liver metastases (CLRMs) (the liver is the dominant metastatic site for CRC) within the context of the Enhanced Recovery After Surgery (ERAS) paradigm. It discusses the epidemiology and outcomes along with the history of hepatic resection surgery and pertinent anatomy. The discussion of the preoperative phase includes patient selection, assessment of liver functional status, and new developments in prehabilitation. The intraoperative phase details developments in surgical and anesthetic techniques to minimize liver hemorrhage and reduce the risk of postoperative hepatic failure. Newer analgesic options are included. Management of potential complications is outlined in the postoperative section followed by a description of current evidence for ERAS and future directions.

The physiological and clinical importance of cardiorespiratory fitness in people with abdominal aortic aneurysm

New Findings

What is the topic of this review?

This review focuses on the physiological impact of abdominal aortic aneurysm (AAA) on cardiorespiratory fitness and the negative consequences of low fitness on clinical outcomes in AAA. We also discuss the efficacy of exercise training for improving cardiorespiratory fitness in AAA.

What advances does it highlight?

We demonstrate the negative impact of low fitness on disease progression and clinical outcomes in AAA. We highlight potential mechanistic determinants of low fitness in AAA and present evidence that exercise training can be an effective treatment strategy for improving cardiorespiratory fitness, postoperative mortality and disease progression.

Abstract

An abdominal aortic aneurysm (AAA) is an abnormal enlargement of the aorta, below the level of the renal arteries, where the aorta diameter increases by >50%. As an aneurysm increases in size, there is a progressive increase in the risk of rupture, which ranges from 25 to 40% for aneurysms >5.5 cm in diameter. People with AAA are also at a heightened risk of cardiovascular events and associated mortality. Cardiorespiratory fitness is impaired in people with AAA and is associated with poor (postoperative) clinical outcomes, including increased length of hospital stay and postoperative mortality after open surgical or endovascular AAA repair. Although cardiorespiratory fitness is a well‐recognized prognostic marker of cardiovascular health and mortality, it is not assessed routinely, nor is it included in current clinical practice guidelines for the management of people with AAA. In this review, we discuss the physiological impact of AAA on cardiorespiratory fitness, in addition to the consequences of low cardiorespiratory fitness on clinical outcomes in people with AAA. Finally, we summarize current evidence for the effect of exercise training interventions on cardiorespiratory fitness in people with AAA, including the associated improvements in postoperative mortality, AAA growth and cardiovascular risk. Based on this review, we propose that cardiorespiratory fitness should be considered as part of the routine risk assessment and monitoring of people with AAA and that targeting improvements in cardiorespiratory fitness with exercise training might represent a viable adjunct treatment strategy for reducing postoperative mortality and disease progression.

The Content of Pre-habilitative Interventions for Patients Undergoing Repair of Abdominal Aortic Aneurysms and Their Effect on Post-Operative Outcomes: A Systematic Review

OBJECTIVE

Patients requiring abdominal aortic aneurysm (AAA) repair are at risk of post-operative complications due to poor pre-operative state. Pre-habilitation describes the enhancement of functional capacity and tolerance to an upcoming physiological stressor, intended to reduce those complications. The ability to provide such an intervention (physical, pharmacological, nutritional, or psychosocial) between diagnosis and surgery is a growing interest, but its role in AAA repair is unclear. This paper aimed to systematically review existing literature to better describe the effect of pre-habilitative interventions on post-operative outcomes of patients undergoing AAA repair.

DATA SOURCES

EMBASE and Medline were searched from inception to October 2020. Retrieved papers, systematic reviews, and trial registries were citation tracked.

REVIEW METHODS

Randomised controlled trials (RCTs) comparing post-operative outcomes for adult patients undergoing a period of pre-habilitation prior to AAA repair (open or endovascular) were eligible for inclusion. Two authors screened titles for inclusion, assessed risk of bias, and extracted data. Primary outcomes were post-operative 30 day mortality, composite endpoint of 30 day post-operative complications, hospital length of stay (LOS), and health related quality of life (HRQL) outcomes. The content of interventions was extracted and a narrative analysis of results undertaken.

RESULTS

Seven RCTs with 901 patients were included (three exercise based, two pharmacological based, and two nutritional based). Risk of bias was mostly unclear or high and the clinical heterogeneity between the trials precluded data pooling for meta-analyses. The quality of intervention descriptions was highly variable. One exercise based RCT reported significantly reduced hospital LOS and another improved HRQL outcomes. Neither pharmacological nor nutritional based RCTs reported significant differences in primary outcomes.

CONCLUSION

There is limited evidence to draw clinically robust conclusions about the effect of pre-habilitation on post-operative outcomes following AAA repair. Well designed RCTs, adhering to reporting standards for intervention content and trial methods, are urgently needed to establish the clinical and cost effectiveness of pre-habilitation interventions.

Editor's Choice - Development and Validation of a Multivariable Prediction Model of Peri-operative Mortality in Vascular Surgery: The New Zealand Vascular Surgical Risk Tool (NZRISK-VASC)

OBJECTIVE

Risk calculators and prediction models are available to assist clinicians and patients with peri-operative decision making to optimise outcomes. In a vascular surgical setting, the majority of these models is based on open AAA repair outcomes, and in general their clinical use is limited. The objective of this study was to develop and validate a simple and accurate vascular surgical risk prediction model.

METHODS

A national administrative database was accessed to collect information on all adult patients undergoing vascular surgery between 1 July 2011 and 30 June 2016 in New Zealand. The primary outcomes were mortality at 30 days, one year, and two years. Previously established covariables including American Society of Anaesthesiologists (ASA) physical status score, sex, surgical urgency, cancer status and ethnicity were tested, and other covariables such as smoking status, presence of renal failure, diabetes, anatomical site of operation, structure operated, and type of procedures (open or endovascular) were explored. LASSO regression was used to select variables for inclusion in the model.

RESULTS

A total of 21 597 cases formed the final risk prediction models, with covariables including ASA score, gender, surgical urgency, cancer status, presence of renal failure, diabetes, anatomical site, structure operated, and endovascular procedure. The area under the receiver operating curve (AUROC) for 30 day, one year, and two year mortality using L-min model was 0.869, 0.833, and 0.824, respectively, demonstrating very good discrimination. Calibration with the validation dataset was also excellent, with slopes of 0.971, 1.129, and 1.011, respectively, and McFadden's pseudo-R² statistics of 0.250, 0.227, and 0.227, respectively.

CONCLUSION

A simple and accurate multivariable risk calculator for vascular surgical patients was developed and validated using the New Zealand national dataset, with excellent discrimination and calibration for 30 day, one year, and two year mortality.

Cardiorespiratory fitness fails to predict short-term postoperative mortality in patients undergoing elective open surgery for abdominal aortic aneurysm

INTRODUCTION

Preoperative cardiopulmonary exercise testing aids surgical risk stratification and is an established predictor of mid- to long-term survival in patients undergoing elective open abdominal aortic aneurysm repair. Whether cardiopulmonary exercise testing also predicts 30-day mortality in this population remains to be established.

MATERIALS AND METHODS

Data for 109 patients (mean age 72 years) who underwent cardiopulmonary exercise testing to assess risk for surgical abdominal aortic aneurysm repair was analysed. Patients were classified according to cardiopulmonary fitness as fit (peak oxygen uptake ≥ 15ml O₂.kg^-1.min^-1) or unfit (peak oxygen uptake less than 15ml O₂.kg^-1.min^-1) and further stratified according to clamp position (infrarenal or suprarenal). Between-group postoperative outcomes were compared for in-hospital 30-day mortality, postoperative morbidity scale scores (day 5) and hospital length of stay.

RESULTS

Seventy-nine patients underwent open surgery and 30 patients were treated conservatively. No deaths were recorded at 30 days post-surgery. Unfit patients with infrarenal clamping exhibited higher postoperative morbidity scale scores (64% vs 26%) and longer length of stay (four days) than fit patients (p < 0.05). Conversely, with suprarenal clamping, postoperative morbidity scale scores were similar and length of stay longer (three days) in fit compared with unfit patients (p < 0.05).

DISCUSSION AND CONCLUSION

Preoperative fitness level defined by peak oxygen uptake failed to identify patients at risk of 30-day mortality when undergoing elective abdominal aortic aneurysm repair. Postoperative morbidity and length of stay in patients with suprarenal clamping was high independent of cardiopulmonary fitness. These findings suggest that cardiopulmonary exercise testing may be a useful predictor of complications following infrarenal rather than suprarenal clamping but may not be a good predictor of 30-day mortality.

Variables associated with survival in patients with invasive bladder cancer with and without surgery

We recorded the survival of 141 patients assessed for radical cystectomy, which included cardiopulmonary exercise testing. The median Kaplan-Meier survival estimates were: 1540 days for the whole cohort; 2200 days after cystectomy scheduled (n = 108); and 843 days without surgery. The mortality hazard remained double that expected for a matched general population, but survival was better in patients scheduled for surgery than those who were not: the mortality hazard ratio (95%CI) after cystectomy was 0.43 (0.26-0.73) the mortality hazard without surgery, p = 0.001. The mortality hazard ratios for the three-variable Bayesian Model Averaging survival model for all 141 patients were: referral for surgery (0.5); haemoglobin concentration (0.98); and efficiency of carbon dioxide output (1.05). Efficiency of carbon dioxide output was the single variable in the postoperative model (n = 108), mortality hazard 1.08 (per unit increase). The ratio of observed to expected peak oxygen consumption associated best with mortality in 33 patients not referred for surgery, hazard ratio 0.001. Our results can inform consultations with patients with invasive bladder cancer and suggest that interventions to increase fitness and haemoglobin may improve survival in patients who do and who do not undergo radical cystectomy.

Cardiopulmonary Exercise Testing for Preoperative Evaluation: What Does the Future Hold?

Purpose of Review

Cardiopulmonary exercise testing (CPET) informs the preoperative evaluation process by providing individualised risk profiles; guiding shared decision-making, comorbidity optimisation and preoperative exercise training; and informing perioperative patient management. This review summarises evidence on the role of CPET in preoperative evaluation and explores the role of novel and emerging CPET variables and alternative testing protocols that may improve the precision of preoperative evaluation in the future.

Recent Findings

CPET provides a wealth of physiological data, and to date, much of this is underutilised clinically. For example, impaired chronotropic responses during and after CPET are simple to measure and in recent studies are predictive of both cardiac and noncardiac morbidity following surgery but are rarely reported. Exercise interventions are increasingly being used preoperatively, and endurance time derived from a high intensity constant work rate test should be considered as the most sensitive method of evaluating the response to training. Further research is required to identify the clinically meaningful difference in endurance time. Measuring efficiency may have utility, but this requires exploration in prospective studies.

Summary

Further work is needed to define contemporaneous risk thresholds, to explore the role of other CPET variables in risk prediction, to better characterise CPET’s role in combination with other tools in multifactorial risk stratification and increasingly to evaluate CPET’s utility for preoperative exercise prescription in prehabilitation.

Shared decision making for elective abdominal aortic aneurysm surgery

Decisions on how and when to treat an abdominal aortic aneurysm involve a number of clinicians; interventional radiologists and vascular surgeons assess the technical ability to repair the aneurysm. Patients' fitness and past medical history is assessed to estimate their short- and long-term survival with or without surgery. Most importantly the patients' personal preference for treatment must be identified. Getting a patient to share what matters most to them requires shared decision making.

Anaerobic threshold as an independent predictor of mid-term survival following elective endovascular repair of abdominal aortic aneurysm

BACKGROUND

The aim of this study was to examine the value preoperative AT as predictor of postoperative survival in patients who underwent elective EVAR for repair of asymptomatic AAA.

METHODS

Consecutive patients who underwent elective EVAR between 2008 and 2018 were analyzed. Cardiopulmonary exercise testing was performed. Perioperative 30-day mortality was compared between patients who had AT ≥8 mL/kg/min and those with AT<8 mL/kg/min. Risk factors for postoperative survival following EVAR were examined using Cox's regression analysis.

RESULTS

Between 1^st January 2008 and 31^st December 2017, 430 patients underwent elective EVAR (standard device: N.=374, fenestrated/branched: N.=56); their median age was 76 years (range: 53-91 years), median AT was 9.3 (range: 5.4-16.1), and 30-day mortality was 0.9%. These patients were followed up for a median of 1630 days. There was no significant difference in perioperative 30-day mortality between patients who had AT≥8 and those who had AT<8 (χ²=1.56, P=0.22). Age (HR=1.51 [CI: 1.07-1.99], P<0.05) and AT (HR=0.59 [CI: 0.45-0.76], P=0.0003) were predictors of reduced postoperative survival following elective EVAR whereas gender (HR=0.75 [CI: 0.4-1.4], P=0.37), AAA diameter (HR=0.95 [CI: 0.77-1.16], P=0.6), and AAA morphology (HR=1.23 [CI: 0.68-1.76], P=0.95) were not.

CONCLUSIONS

Anaerobic threshold is an independent predictor of prolonged survival following elective EVAR and can be used to identify patients who receive most benefit from elective EVAR.

Influence of psoas muscle area on mortality following elective abdominal aortic aneurysm repair

BACKGROUND

The effect of sarcopenia based on the total psoas muscle area (TPMA) on CT is inconclusive in patients undergoing abdominal aortic aneurysm (AAA) intervention. The aim of this prospective cohort study was to evaluate morphometric sarcopenia as a method of risk stratification in patients undergoing elective AAA intervention.

METHODS

TPMA was measured on preintervention CT images of patients undergoing elective endovascular aneurysm repair (EVAR) or open aneurysm repair. Mortality was assessed in relation to preintervention TPMA using Cox regression analysis, with calculation of hazard ratios at 30 days, 1 year and 4 years. Postintervention morbidity was evaluated in terms of postintervention care, duration of hospital stay and 30-day readmission. Changes in TPMA on surveillance EVAR imaging were also evaluated.

RESULTS

In total, 382 patient images acquired between March 2008 and December 2016 were analysed. There were no significant intraobserver and interobserver differences in measurements of TPMA. Preintervention TPMA failed to predict morbidity and mortality at all time points. The mean(s.d.) interval between preintervention and surveillance imaging was 361·3(111·2) days. A significant reduction in TPMA was observed in men on surveillance imaging after EVAR (mean reduction 0·63(1·43) cm2 per m2 ; P < 0·001). However, this was not associated with mortality (adjusted hazard ratio 1·00, 95 per cent c.i. 0·99 to 1·01; P = 0·935).

CONCLUSION

TPMA is not a suitable risk stratification tool for patients undergoing effective intervention for AAA.

Using predicted 30 day mortality to plan postoperative colorectal surgery care: a cohort study

BACKGROUND

Preoperative identification of high-risk surgical patients might help to reduce postoperative morbidity and mortality. Using a patient's predicted 30 day mortality to plan postoperative high-dependency unit (HDU) care after elective colorectal surgery might be associated with reduced postoperative morbidity.

METHODS

The 30 day postoperative mortality was predicted for 504 elective colorectal surgical patients in a preoperative clinic. The prediction was used to determine postoperative surgical ward or HDU care. Those with a predicted 30 day mortality of 1-3% mortality, and thus deemed at intermediate risk, had either planned HDU care (n=68) or planned ward care (n=139). The main outcome measures were emergency laparotomy and unplanned critical care admission.

RESULTS

There were more emergency laparotomies and unplanned critical care admissions in patients with a predicted 30 day mortality of 1-3% who went to an HDU after surgery compared with patients who went to a ward: 0 vs 14 (10%), P=0.0056 and 0 vs 22 (16%), P=0.0002, respectively.

CONCLUSIONS

Planned postoperative critical care was associated with a lower rate of complications after elective colorectal surgery.

ICU admission after surgery: who benefits?

PURPOSE OF REVIEW

Death following surgery remains a major cause of death worldwide, and ICU admission following major surgery is considered a standard of care in many healthcare systems. However, ICU resources are finite and expensive, thus identifying those most likely to benefit is of great importance.

RECENT FINDINGS

Advances in surgical and perioperative management have moved the focus of postoperative care to preventing complications and reducing duration of hospitalisation. Recent health services research has failed to find association between ICU admission and improved outcome in many types of elective major noncardiac surgery. Use of alternatives to ICU such as post anaesthesia care units (PACUs), high dependency units (HDUs) or specialist wards with enhanced nursing care are able to perform some elements of ICU monitoring in a less intensive environment, and may provide a better alternative to the traditional model of ICU admission for many patients having major surgery. ICU admission should still be considered for very high-risk patients and those having complex or emergency surgery. Improved triage tools are required to identify those at the highest risk of death or complications.

SUMMARY

Identifying those most at risk of death and complications following surgery and preventing them is the major challenge of perioperative care in the coming decades. Future research should focus on how postoperative care can best be structured to provide optimum care to patients within available resources. Incidence of complications or failure to rescue (FtR) may provide useful metrics in future research.

Risk Assessment

Purpose of Review

The central question of preoperative assessment is not “What can be done?” but “What should be done and how?” Predicting a patient’s risk of unwanted outcomes is vital to answering this question. This review discusses risk prediction tools currently available and anticipates future developments.

Recent Findings

Simple, parsimonious risk scales and scores are being replaced by complex risk prediction models as high-capacity information systems become ubiquitous. The accuracy of risk estimation will be further increased by improved assessment of physical fitness, frailty, and incorporation of existing and novel biomarkers. However, the limitations of risk prediction for individual patient care must be recognized.

Summary

Risk prediction is transforming from clinical estimation to statistical science. Predictions should be used within the context of a patient’s baseline risk (life expectancy independent of surgery), personal circumstances, quality of life, their expectations and values, and consideration of outcomes that are meaningful for the patient.

Cardiopulmonary exercise testing (CPET) in the United Kingdom-a national survey of the structure, conduct, interpretation and funding

Background

Cardiopulmonary exercise testing (CPET) is an exercise stress test with concomitant expired gas analysis that provides an objective, non-invasive measure of functional capacity under stress. CPET-derived variables predict postoperative morbidity and mortality after major abdominal and thoracic surgery. Two previous surveys have reported increasing utilisation of CPET preoperatively in England. We aimed to evaluate current CPET practice in the UK, to identify who performs CPET, how it is performed, how the data generated are used and the funding models.

Methods

All anaesthetic departments in trusts with adult elective surgery in the UK were contacted by telephone to obtain contacts for their pre-assessment and CPET service leads. An online survey was sent to all leads between November 2016 and March 2017.

Results

The response rate to the online survey was 73.1% (144/197) with 68.1% (98/144) reporting an established clinical service and 3.5% (5/144) setting up a service. Approximately 30,000 tests are performed a year with 93.0% (80/86) using cycle ergometry. Colorectal surgical patients are the most frequently tested (89.5%, 77/86). The majority of tests are performed and interpreted by anaesthetists. There is variability in the methods of interpretation and reporting of CPET and limited external validation of results.

Conclusions

This survey has identified the continued expansion of perioperative CPET services in the UK which have doubled since 2011. The vast majority of CPET tests are performed and reported by anaesthetists. It has highlighted variation in practice and a lack of standardised reporting implying a need for practice guidelines and standardised training to ensure high-quality data to inform perioperative decision making.

Randomized feasibility trial of high-intensity interval training before elective abdominal aortic aneurysm repair

Background

This study assessed the feasibility of a preoperative high-intensity interval training (HIT) programme in patients awaiting elective abdominal aortic aneurysm repair.

Methods

In this feasibility trial, participants were allocated by minimization to preoperative HIT or usual care. Patients in the HIT group were offered three exercise sessions per week for 4 weeks, and weekly maintenance sessions if surgery was delayed. Feasibility and acceptability outcomes were: rates of screening, eligibility, recruitment, retention, outcome completion, adverse events and adherence to exercise. Data on exercise enjoyment (Physical Activity Enjoyment Scale, PACES), cardiorespiratory fitness (anaerobic threshold and peak oxygen uptake), quality of life, postoperative morbidity and mortality, duration of hospital stay and healthcare utilization were also collected.

Results

Twenty-seven patients were allocated to HIT and 26 to usual care (controls). Screening, eligibility, recruitment, retention and outcome completion rates were 100 per cent (556 of 556), 43·2 per cent (240 of 556), 22·1 per cent (53 of 240), 91 per cent (48 of 53) and 79–92 per cent respectively. The overall exercise session attendance rate was 75·8 per cent (276 of 364), and the mean(s.d.) PACES score after the programme was 98(19) (‘enjoyable’); however, the intensity of exercise was generally lower than intended. The mean anaerobic threshold after exercise training (adjusted for baseline score and minimization variables) was 11·7 ml per kg per min in the exercise group and 11·4 ml per kg per min in controls (difference 0·3 (95 per cent c.i. –0·4 to 1·1) ml per kg per min). There were trivial-to-small differences in postoperative clinical and patient-reported outcomes between the exercise and control groups.

Conclusion

Despite the intensity of exercise being generally lower than intended, the findings support the feasibility and acceptability of both preoperative HIT and the trial procedures. A definitive trial is warranted. Registration number: ISRCTN09433624 (https://www.isrctn.com/).

External validation of a 5-year survival prediction model after elective abdominal aortic aneurysm repair

OBJECTIVE

The benefit of prophylactic repair of abdominal aortic aneurysms (AAAs) is based on the risk of rupture exceeding the risk of death from other comorbidities. The purpose of this study was to validate a 5-year survival prediction model for patients undergoing elective repair of asymptomatic AAA <6.5 cm to assist in optimal selection of patients.

METHODS

All patients undergoing elective repair for asymptomatic AAA <6.5 cm (open or endovascular) from 2002 to 2011 were identified from a single institutional database (validation group). We assessed the ability of a prior published Vascular Study Group of New England (VSGNE) model (derivation group) to predict survival in our cohort. The model was assessed for discrimination (concordance index), calibration (calibration slope and calibration in the large), and goodness of fit (score test).

RESULTS

The VSGNE derivation group consisted of 2367 patients (70% endovascular). Major factors associated with survival in the derivation group were age, coronary disease, chronic obstructive pulmonary disease, renal function, and antiplatelet and statin medication use. Our validation group consisted of 1038 patients (59% endovascular). The validation group was slightly older (74 vs 72 years; P < .01) and had a higher proportion of men (76% vs 68%; P < .01). In addition, the derivation group had higher rates of advanced cardiac disease, chronic obstructive pulmonary disease, and baseline creatinine concentration (1.2 vs 1.1 mg/dL; P < .01). Despite slight differences in preoperative patient factors, 5-year survival was similar between validation and derivation groups (75% vs 77%; P = .33). The concordance index of the validation group was identical between derivation and validation groups at 0.659 (95% confidence interval, 0.63-0.69). Our validation calibration in the large value was 1.02 (P = .62, closer to 1 indicating better calibration), calibration slope of 0.84 (95% confidence interval, 0.71-0.97), and score test of P = .57 (>.05 indicating goodness of fit).

CONCLUSIONS

Across different populations of patients, assessment of age and level of cardiac, pulmonary, and renal disease can accurately predict 5-year survival in patients with AAA <6.5 cm undergoing repair. This risk prediction model is a valid method to assess mortality risk in determining potential overall survival benefit from elective AAA repair.

Current research priorities in perioperative intensive care medicine

INTRODUCTION

Surgical treatments are offered to more patients than ever before, and increasingly to older patients with chronic disease. High-risk patients frequently require critical care either in the immediate postoperative period or after developing complications. The purpose of this review was to identify and prioritise themes for future research in perioperative intensive care medicine.

METHODS

We undertook a priority setting process (PSP). A panel was convened, drawn from experts representing a wide geographical area, plus a patient representative. The panel was asked to suggest and prioritise key uncertainties and future research questions in the field of perioperative intensive care through a modified Delphi process. Clinical trial registries were searched for on-going research. A proposed "Population, Intervention, Comparator, Outcome" (PICO) structure for each question was provided.

RESULTS

Ten key uncertainties and future areas of research were identified as priorities and ranked. Appropriate intravenous fluid and blood component therapy, use of critical care resources, prevention of delirium and respiratory management featured prominently.

CONCLUSION

Admissions following surgery contribute a substantial proportion of critical care workload. Studies aimed at improving care in this group could have a large impact on patient-centred outcomes and optimum use of healthcare resources. In particular, the optimum use of critical care resources in this group is an area that requires urgent research.

Mitochondrial Therapies in Heart Failure

The current therapy for patients with stable systolic heart failure is largely limited to treatments that interfere with neurohormonal activation. Critical pathophysiological hallmarks of heart failure are an energetic deficit and oxidative stress, and both may be the result of mitochondrial dysfunction. This dysfunction is not (only) the result of defect within mitochondria per se, but is in particular traced to defects in intermediary metabolism and of the regulatory interplay between excitation-contraction coupling and mitochondrial energetics, where defects of cytosolic calcium and sodium handling in failing hearts may play important roles. In the past years, several therapies targeting mitochondria have emerged with promising results in preclinical models. Here, we discuss the mechanisms and results of these mitochondria-targeted therapies, but also of interventions that were not primarily thought to target mitochondria but may have important impact on mitochondrial biology as well, such as iron and exercise. Future research should be directed at further delineating the details of mitochondrial dysfunction in patients with heart failure to further optimize these treatments.

Simulations of the effects of scheduled abdominal aortic aneurysm repair on survival

I simulated survival with and without scheduled repair of abdominal aortic aneurysms with different diameters in different populations. The results imply that scheduled repair should be determined by the combination of a patient's monthly mortality hazard and aneurysm diameter. The median survival of some patients will be extended by the scheduled repair of aneurysms smaller than 55 mm, whereas the median survival of other patients will be curtailed by repair of any aneurysm. The results also suggest that, on average, surveillance is futile: the effect of scheduled aneurysm repair on an individual's median survival did not change but the cohort effect diminished as patients died during surveillance. The results of the U.K. Small Aneurysm Study were reproduced in simulation and are compatible with the repair of aneurysms smaller than 55 mm diameter. Epidemiological simulations suggest that past randomised controlled trials underestimate the effect of aneurysm repair today.