Machine learning and preoperative risk prediction: the machines are coming.

Preoperative risk prediction is an important component of perioperative medicine. Machine learning is a powerful tool that could lead to increasingly complex risk prediction models with improved predictive performance. Careful consideration is required to guide the machine learning approach to ensure appropriate decisions are made with regard to what we are trying to predict, when we are trying to predict it, and what we seek to do with the results.

Do we have the 'power' to 'drive' down the incidence of pulmonary complications after thoracic surgery.

The concept, mechanisms, and physical and physiological determinants of ventilator-induced lung injury, as well as the influence of lung-protective ventilation strategies, are novel paradigms of modern intensive care and perioperative medicine. Driving pressure and mechanical power have emerged as meaningful and modifiable targets with specific relevance to thoracic anaesthesia and one-lung ventilation. The relationship between these factors and postoperative pulmonary complications remains complex because of the methodological design and outcome selection. Larger observational studies are required to better understand the characteristics of driving pressure and power in current practice of thoracic anaesthesia in order to design future trials in high-risk thoracic populations at risk of acute lung injury.

Thoracic anaesthetic research: 90 years of sustained progress.

Over the 90 years since the first description of one-lung ventilation, the practice of thoracic surgery and anaesthesia continues to develop. Minimally invasive surgical techniques are increasingly being used to minimise the surgical insult and facilitate improved outcomes. Challenging these outcomes, however, are parallel changes in patient characteristics with more older and sicker patients undergoing surgery. Thoracic anaesthesia as a speciality continues to respond to these challenges with evolution of practice and strong academic performance.

Pulmonary artery wave reflection and right ventricular function after lung resection.

BACKGROUND: Lung resection has been shown to impair right ventricular function. Although conventional measures of afterload do not change, surgical ligation of a pulmonary artery branch, as occurs during lobectomy, can create a unilateral proximal reflection site, increasing wave reflection (pulsatile component of afterload) and diverting blood flow through the contralateral pulmonary artery. We present a cardiovascular magnetic resonance imaging (MRI) observational cohort study of changes in wave reflection and right ventricular function after lung resection. METHODS: Twenty-seven patients scheduled for open lobectomy for suspected lung cancer underwent cardiovascular MRI preoperatively, on postoperative Day 2, and at 2 months. Wave reflection was assessed in the left and right pulmonary arteries (operative and non-operative, as appropriate) by wave intensity analysis and calculation of wave reflection index. Pulmonary artery blood flow distribution was calculated as percentage of total blood flow travelling in the non-operative pulmonary artery. Right ventricular function was assessed by ejection fraction and strain analysis. RESULTS: Operative pulmonary artery wave reflection increased from 4.3 (2.1-8.8) % preoperatively to 9.5 (4.9-14.9) % on postoperative Day 2 and 8.0 (2.3-11.7) % at 2 months (P<0.001) with an associated redistribution of blood flow towards the nonoperative pulmonary artery (r>0.523; P<0.010). On postoperative Day 2, impaired right ventricular ejection fraction was associated with increased operative pulmonary artery wave reflection (r=-0.480; P=0.028) and pulmonary artery blood flow redistribution (r=-0.545; P=0.011). At 2 months, impaired right ventricular ejection fraction and right ventricular strain were associated with pulmonary artery blood flow redistribution (r=-0.634, P=0.002; r=0.540, P=0.017). CONCLUSIONS: Pulsatile afterload increased after lung resection. The unilateral increase in operative pulmonary artery wave reflection resulted in redistribution of blood flow through the nonoperative pulmonary artery and was associated with right ventricular dysfunction. CLINICAL TRIAL REGISTRATION: NCT01892800.

Perioperative cardiovascular pathophysiology in patients undergoing lung resection surgery: a narrative review.

Although thoracic surgery is understood to confer a high risk of postoperative respiratory complications, the substantial haemodynamic challenges posed are less well appreciated. This review highlights the influence of cardiovascular comorbidity on outcome, reviews the complex pathophysiological changes inherent in one-lung ventilation and lung resection, and examines their influence on cardiovascular complications and postoperative functional limitation. There is now good evidence for the presence of right ventricular dysfunction postoperatively, a finding that persists to at least 3 months. This dysfunction results from increased right ventricular afterload occurring both intraoperatively and persisting postoperatively. Although many patients adapt well, those with reduced right ventricular contractile reserve and reduced pulmonary vascular flow reserve might struggle. Postoperative right ventricular dysfunction has been implicated in the aetiology of postoperative atrial fibrillation and perioperative myocardial injury, both common cardiovascular complications which are increasingly being appreciated to have impact long into the postoperative period. In response to the physiological demands of critical illness or exercise, contractile reserve, flow reserve, or both can be overwhelmed resulting in acute decompensation or impaired long-term functional capacity. Aiding adaptation to the unique perioperative physiology seen in patients undergoing thoracic surgery could provide a novel therapeutic avenue to prevent cardiovascular complications and improve long-term functional capacity after surgery.

Association Between Anesthetic Dose and Technique and Oncologic Outcomes After Surgical Resection of Non-Small Cell Lung Cancer.

OBJECTIVES: Because of the biologic effects of volatile anesthetics on the immune system and cancer cells, it has been hypothesized that their use during non-small cell lung cancer (NSCLC) surgery may negatively affect cancer outcomes compared with total intravenous anesthesia (TIVA) with propofol. The present study evaluated the relationship between anesthetic technique and dose and oncologic outcome in NSCLC surgery. DESIGN: Retrospective cohort study. SETTING: Surgical records collated from a single, tertiary care hospital and combined with the Scottish Cancer Registry and continuously recorded electronic anesthetic data. PARTICIPANTS: Patients undergoing elective lung resection for NSCLC between January 2010 and December 2014. INTERVENTIONS: The cohort was divided into patients receiving TIVA only and patients exposed to volatile anesthetics. MEASUREMENTS AND MAIN RESULTS: Final analysis included 746 patients (342 received TIVA and 404 volatile anesthetic). Kaplan-Meier survival curves with log-rank testing were drawn for cancer-specific and overall survival. No significant differences were demonstrated for either cancer-specific (p = 0.802) or overall survival (p = 0.736). Factors influencing survival were analyzed using Cox proportional hazards modeling. Anesthetic type was not a significant predictor for cancer-specific or overall survival in univariate or multivariate Cox analysis. Volatile anesthetic exposure was quantified using area under the end-tidal expired anesthetic agent versus time curves. This was not significantly associated with cancer-specific survival on univariate (p = 0.357) or multivariate (p = 0.673) modeling. CONCLUSIONS: No significant relationship was demonstrated between anesthetic technique and NSCLC survival. Whether a causal relationship exists between anesthetic technique during NSCLC surgery and oncologic outcome warrants definitive investigation in a prospective, randomized trial.

Thoracic Anesthesia during the COVID-19 Pandemic: 2021 Updated Recommendations by the European Association of Cardiothoracic Anaesthesiology and Intensive Care (EACTAIC) Thoracic Subspecialty Committee.

The novel coronavirus pandemic has radically changed the landscape of normal surgical practice. Lifesaving cancer surgery, however, remains a clinical priority, and there is an increasing need to fully define the optimal oncologic management of patients with varying stages of lung cancer, allowing prioritization of which thoracic procedures should be performed in the current era. Healthcare providers and managers should not ignore the risk of a bimodal peak of mortality in patients with lung cancer; an imminent spike due to mortality from acute coronavirus disease 2019 (COVID-19) infection, and a secondary peak reflecting an excess of cancer-related mortality among patients whose treatments were deemed less urgent, delayed, or cancelled. The European Association of Cardiothoracic Anaesthesiology and Intensive Care Thoracic Anesthesia Subspecialty group has considered these challenges and developed an updated set of expert recommendations concerning the infectious period, timing of surgery, vaccination, preoperative screening and evaluation, airway management, and ventilation of thoracic surgical patients during the COVID-19 pandemic.

Thoracic Anesthesia of Patients With Suspected or Confirmed 2019 Novel Coronavirus Infection: Preliminary Recommendations for Airway Management by the European Association of Cardiothoracic Anaesthesiology Thoracic Subspecialty Committee.

The novel coronavirus has caused a pandemic around the world. Management of patients with suspected or confirmed coronavirus infection who have to undergo thoracic surgery will be a challenge for the anesthesiologists. The thoracic subspecialty committee of European Association of Cardiothoracic Anaesthesiology (EACTA) has conducted a survey of opinion in order to create recommendations for the anesthetic approach to these challenging patients. It should be emphasized that both the management of the infected patient with COVID-19 and the self-protection of the anesthesia team constitute a complicated challenge. The text focuses therefore on both important topics.

Interoperator and intraoperator variability of whole blood coagulation assays: a comparison of thromboelastography and rotational thromboelastometry.

OBJECTIVES: Near-patient viscoelastic tests have proved useful in decreasing blood and blood product use in cardiac surgery. Two different analyzers are available, TEG and ROTEM. Many different individuals operate these devices, which raises concern that this factor may significantly affect results. The present study sought to objectively assess variability in results between operators. DESIGN: Prospective study. SETTING: Regional cardiac center. PARTICIPANTS: Adult patients undergoing elective cardiac surgery. INTERVENTIONS: Thirty-six mL of blood were taken from each of 21 patients. TEG kaolin and functional fibrinogen (FF) analyses and the equivalent ROTEM INTEM S and FIBTEM S analyses were performed. Six operators performed one of each test per patient to assess interoperator variability. One further operator performed 6 of each test per patient to assess intraoperator variability. MEASUREMENTS AND MAIN RESULTS: All routine measurement parameters were noted and the coefficient of variation (CV) calculated, analyzing comparable parameters. All inter-operator CVs were significantly lower for ROTEM analyses compared with TEG. CV for INTEM S CT/ kaolin r time was 4.7 versus 16.3 and MCF/MA was 2.6 versus 4.3 (p < 0.01). Similarly, FIBTEM S MCF/ FF MA was 8.3 versus 12.2. All intraoperator CVs were significantly lower for ROTEM analyses compared with TEG (p<0.01). CV for INTEM S CT/kaolin r time was 3.1 versus 9.8 and MCF/ MA was 1.6 versus 4. Similarly, FIBTEM S MCF/ MA was 6.9 versus 12.1. CONCLUSIONS: This series of results suggested ROTEM analyses are more reproducible than TEG and, consequently, that ROTEM may be better suited for use in a multiuser environment.

Epidemiology of perioperative RV dysfunction: risk factors, incidence, and clinical implications.

In this edition of the journal, the Perioperative Quality Initiative (POQI) present three manuscripts describing the physiology, assessment, and management of right ventricular dysfunction (RVD) as pertains to the perioperative setting. This narrative review seeks to provide context for these manuscripts, discussing the epidemiology of perioperative RVD focussing on definition, risk factors, and clinical implications. Throughout the perioperative period, there are many potential risk factors/insults predisposing to perioperative RVD including pre-existing RVD, fluid overload, myocardial ischaemia, pulmonary embolism, lung injury, mechanical ventilation, hypoxia and hypercarbia, lung resection, medullary reaming and cement implantation, cardiac surgery, cardiopulmonary bypass, heart and lung transplantation, and left ventricular assist device implantation. There has however been little systematic attempt to quantify the incidence of perioperative RVD. What limited data exists has assessed perioperative RVD using echocardiography, cardiovascular magnetic resonance, and pulmonary artery catheterisation but is beset by challenges resulting from the inconsistencies in RVD definitions. Alongside differences in patient and surgical risk profile, this leads to wide variation in the incidence estimate. Data concerning the clinical implications of perioperative RVD is even more scarce, though there is evidence to suggest RVD is associated with atrial arrhythmias and prolonged length of critical care stay following thoracic surgery, increased need for inotropic support in revision orthopaedic surgery, and increased critical care requirement and mortality following cardiac surgery. Acute manifestations of RVD result from low cardiac output or systemic venous congestion, which are non-specific to the diagnosis of RVD. As such, RVD is easily overlooked, and the relative contribution of RV dysfunction to postoperative morbidity is likely to be underestimated.We applaud the POQI group for highlighting this important condition. There is undoubtedly a need for further study of the RV in the perioperative period in addition to solutions for perioperative risk prediction and management strategies. There is much to understand, study, and trial in this area, but importantly for our patients, we are increasingly recognising the importance of these uncertainties.

Feasibility of 2-dimensional speckle tracking echocardiography strain analysis of the right ventricle with trans-thoracic echocardiography in intensive care: a literature review and meta-analysis.

OBJECTIVES: To identify variables that affect the feasibility of 2-dimensional right ventricular speckle tracking echocardiography (RV-STE) in the intensive care unit. BACKGROUND: Trans-thoracic echocardiography (TTE) of the right ventricle is challenging. RV-STE is a novel echocardiography method thought to measure global RV function more fully than conventional TTE parameters. The feasibility of RV-STE in ICU populations has not been well described, and variables influencing RV-STE in ICU have not been investigated. This study aimed to address this. METHODS: A literature review using Ovid MEDLINE(R) was undertaken. We performed meta-analysis with subgroup analysis of; RV-STE type (RV free-wall [RVFWLS] versus RV global longitudinal strain [RVGLS]), study design (prospective versus retrospective), coronavirus disease-19 (COVID-19) study or not, and strain software used. This was followed by meta-regression of proportion of invasive mechanical ventilation (IMV), with and without COVID-19 studies as a co-variate. RESULTS: Eleven relevant studies from the literature search were identified, reporting an overall feasibility of RV-STE of 83.3% (95%CI 74.6-89.4%). Prospective study design was associated with higher feasibility compared with retrospective studies (p = 0.02). There were no statistical differences on univariate analysis between RVFWLS versus RVGLS, COVID-19 study or not, or strain software used. Meta-regression with COVID-19 study as a covariate demonstrated that higher proportions of IMV were significantly associated with worse feasibility (p = 0.04), as were COVID-19 studies (p < 0.01). CONCLUSIONS: We have identified three variables associated with poor feasibility; retrospective study design, COVID-19 studies, and proportion of IMV. A prospective study design should be viewed as gold standard to maximise RV-STE feasibility.

Study protocol for a randomised controlled trial to investigate the effectiveness of thoracic epidural and paravertebral blockade in reducing chronic post-thoracotomy pain: 2 (TOPIC 2).

BACKGROUND: Thoracotomy is considered one of the most painful surgical procedures and can cause debilitating chronic post-surgical pain lasting months or years postoperatively. Aggressive management of acute pain resulting from thoracotomy may reduce the likelihood of developing chronic pain. This trial compares the two most commonly used modes of acute analgesia provision at the time of thoracotomy (thoracic epidural blockade (TEB) and paravertebral blockade (PVB)) in terms of their clinical and cost-effectiveness in preventing chronic post-thoracotomy pain. METHODS: TOPIC 2 is a multi-centre, open-label, parallel group, superiority, randomised controlled trial, with an internal pilot investigating the use of TEB and PVB in 1026 adult (≥ 18 years old) patients undergoing thoracotomy in up to 20 thoracic centres throughout the UK. Patients (N = 1026) will be randomised in a 1:1 ratio to receive either TEB or PVB. During the first year, the trial will include an integrated QuinteT (Qualitative Research Integrated into Trials) Recruitment Intervention (QRI) with the aim of optimising recruitment and informed consent. The primary outcome is the incidence of chronic post-surgical pain at 6 months post-randomisation defined as 'worst chest pain over the last week' equating to a visual analogue score greater than or equal to 40 mm indicating at least a moderate level of pain. Secondary outcomes include acute pain, complications of regional analgesia and surgery, health-related quality of life, mortality and a health economic analysis. DISCUSSION: Both TEB and PVB have been demonstrated to be effective in the prevention of acute pain following thoracotomy and nationally practice is divided. Identification of which mode of analgesia is both clinically and cost-effective in preventing chronic post-thoracotomy pain could ameliorate the debilitating effects of chronic pain, improving health-related quality of life, facilitating return to work and caring responsibilities and resulting in a cost saving to the NHS. TRIAL REGISTRATION: NCT03677856 [ClinicalTrials.gov] registered September 19, 2018. https://clinicaltrials.gov/ct2/show/NCT03677856 . First patient recruited 8 January 2019.

Outcome following unplanned critical care admission after lung resection.

Objectives: Patients undergoing lung resection are at risk of perioperative complications, many of which necessitate unplanned critical care unit admission in the postoperative period. We sought to characterize this population, providing an up-to-date estimate of the incidence of unplanned critical care admission, and to assess critical care and hospital stay, resource use, mortality, and outcomes. Methods: A multicenter retrospective cohort study of patients undergoing lung resection in participating UK hospitals over 2 years. A comprehensive dataset was recorded for each critical care admission (defined as the need for intubation and mechanical ventilation and/or renal replacement therapy), in addition to a simplified dataset in all patients undergoing lung resection during the study period. Multivariable regression analysis was used to identify factors independently associated with critical care outcome. Results: A total of 11,208 patients underwent lung resection in 16 collaborating centers during the study period, and 253 patients (2.3%) required unplanned critical care admission with a median duration of stay of 13 (4-28) days. The predominant indication for admission was respiratory failure (68.1%), with 77.8% of patients admitted during the first 7 days following surgery. Eighty-seven (34.4%) died in critical care. On multivariable regression, only the diagnosis of right ventricular dysfunction and the need for both mechanical ventilation and renal-replacement therapy were independently associated with critical care survival; this model, however, had poor predictive value. Conclusions: Although resource-intensive and subject to prolonged stay, following unplanned admission to critical care after lung resection outcomes are good for many patients; 65.6% of patients survived to hospital discharge, and 62.7% were discharged to their own home.