Diagnostic Accuracy of Vascular Ultrasonography for Postanesthesia Induction Hypotension: A Systematic Review and Network Meta-Analysis.

BACKGROUND: Arterial hypotension commonly occurs after anesthesia induction and is associated with negative clinical outcomes. Point-of-care ultrasound examination has emerged as a modality to predict postinduction hypotension (PIH). We performed a systematic review and network meta-analysis of the predictive performance of point-of-care ultrasound tests for PIH in noncardiac, nonobstetrical routine adult surgery. METHODS: Online databases were searched for diagnostic test accuracy studies of point-of-care ultrasound for predicting PIH up to March 30, 2023. The systematic review followed the Cochrane methodology. A Bayesian diagnostic test accuracy network meta-analysis model was used, with PIH as defined by study authors as the main outcome. Risk of bias and applicability were examined through the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) score. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework was used to assess evidence certainty. RESULTS: A total of 32 studies with 2631 participants were eligible for systematic review. Twenty-six studies with 2258 participants representing 8 ultrasound tests were included in the meta-analysis. Inferior vena cava collapsibility index (22 studies) sensitivity was 60% (95% credible interval [CrI], 49%-72%) and specificity was 83% (CrI, 74%-89%). Carotid artery corrected flow time (2 studies) sensitivity was 91% (CrI, 76%-98%) and specificity was 90% (CrI, 59%-98%). There were serious bias and applicability concerns due to selection bias and inappropriate blinding. The certainty of evidence was very low for all tests. CONCLUSIONS: The predictive performance of point-of-care ultrasound for PIH is uncertain. There is a need for high-quality randomized controlled trials with appropriate blinding and void of selection bias.

[Mechanical management of refractory form of heart failure]. / Prise en charge mécanique de l'insuffisance cardiaque avancée.

Although the initial management of heart failure is essentially pharmacological, the use of mechanical circulatory support may become necessary in advanced forms. In cardiogenic shock, temporary mechanical circulatory support should be considered, while in more stable forms of advanced heart failure, implantation of a long-term left ventricular assist device (LVAD) can prolong survival and improve patient's quality of life. Recent improvements in LVAD technology have reduced post-implant complications, but the procedure is not without risk and requires close clinical follow-up.

Bien que la prise en charge initiale de l'insuffisance cardiaque soit essentiellement pharmacologique, le recours à des assistances circulatoires mécaniques peut devenir nécessaire dans les formes dites avancées. Dans le choc cardiogénique, l'utilisation d'assistances circulatoires mécaniques temporaires est à considérer alors que pour les formes d'insuffisance cardiaque avancée mieux stabilisées, l'implantation d'une assistance ventriculaire gauche de longue durée (Left Ventricular Assist Device - LVAD) permet de prolonger la survie et d'améliorer la qualité de vie des patients. Les améliorations technologiques récentes des LVAD ont permis de diminuer les complications, mais cette intervention n'est pas sans risque et nécessite un suivi clinique rapproché.

Distribution of ventilation and oxygenation in surgical obese patients ventilated with high versus low positive end-expiratory pressure: A substudy of a randomised controlled trial.

BACKGROUND: Intra-operative ventilation using low/physiological tidal volume and positive end-expiratory pressure (PEEP) with periodic alveolar recruitment manoeuvres (ARMs) is recommended in obese surgery patients. OBJECTIVES: To investigate the effects of PEEP levels and ARMs on ventilation distribution, oxygenation, haemodynamic parameters and cerebral oximetry. DESIGN: A substudy of a randomised controlled trial. SETTING: Tertiary medical centre in Geneva, Switzerland, between 2015 and 2018. PATIENTS: One hundred and sixty-two patients with a BMI at least 35 kg per square metre undergoing elective open or laparoscopic surgery lasting at least 120 min. INTERVENTION: Patients were randomised to PEEP of 4 cmH 2 O ( n  = 79) or PEEP of 12 cmH 2 O with hourly ARMs ( n  = 83). MAIN OUTCOME MEASURES: The primary endpoint was the fraction of ventilation in the dependent lung as measured by electrical impedance tomography. Secondary endpoints were the oxygen saturation index (SaO 2 /FIO 2 ratio), respiratory and haemodynamic parameters, and cerebral tissue oximetry. RESULTS: Compared with low PEEP, high PEEP was associated with smaller intra-operative decreases in dependent lung ventilation [-11.2%; 95% confidence interval (CI) -8.7 to -13.7 vs. -13.9%; 95% CI -11.7 to -16.5; P  = 0.029], oxygen saturation index (-49.6%; 95% CI -48.0 to -51.3 vs. -51.3%; 95% CI -49.6 to -53.1; P  < 0.001) and a lower driving pressure (-6.3 cmH 2 O; 95% CI -5.7 to -7.0). Haemodynamic parameters did not differ between the groups, except at the end of ARMs when arterial pressure and cardiac index decreased on average by -13.7 mmHg (95% CI -12.5 to -14.9) and by -0.54 l min -1  m -2 (95% CI -0.49 to -0.59) along with increased cerebral tissue oximetry (3.0 and 3.2% on left and right front brain, respectively). CONCLUSION: In obese patients undergoing abdominal surgery, intra-operative PEEP of 12 cmH 2 O with periodic ARMs, compared with intra-operative PEEP of 4 cmH 2 O without ARMs, slightly redistributed ventilation to dependent lung zones with minor improvements in peripheral and cerebral oxygenation. TRIAL REGISTRATION: NCT02148692, https://clinicaltrials.gov/ct2.

[Cardiac surgery in the time of COVID19 - A narrative of three very unusual cases and lessons learned]. / Chirurgie cardiaque au temps du Covid-19 - Récit de trois cas très inhabituels et leçons retenues.

COVID19 altered and impacted medical and surgical practice around the world. Standard of care and routine procedures are disrupted. Majors shift in personnel, and ad hoc new team as well as delocalization and working with new infrastructures are further challenges to be dealt with. This review of three very unusual scenarios illustrates pitfalls and dangers harbored in the re-shaped landscape of COVID19 exemplifying the narrow path bridging from the medical and surgical comfort zone to uncharted territory and eventually leading to collateral damage.

Le Covid-19 a profondément modifié et sévèrement impacté les pratiques médicales et chirurgicales à long terme. Les standards de prise en charge et les procédures de routine sont altérés, voire perturbés. Des mutations majeures au niveau du personnel et des équipes de même que la délocalisation ou le travail avec de nouvelles infrastructures sont autant de défis à relever, encore aujourd'hui. Trois scénarios inhabituels illustrent les pièges et les dangers qui se cachent dans le paysage marqué par le Covid-19. Ces exemples démontrent la marge étroite entre la zone de confort médicale et chirurgicale classique et l'appréhension d'une situation inhabituelle qui risque d'entraîner des dommages collatéraux pour les patients.

Accountability, research transparency and data reporting.

More than one published paper are often derived from analyzing the same cohort of individuals to make full use of the collected information. Preplanned study outcomes are generally mentioned in open databases while exhaustive information on methodological aspects are provided in submitted articles.

Pretreatment with glucose-insulin-potassium improves ventricular performances after coronary artery bypass surgery: a randomized controlled trial.

Heart failure is the main cause of poor outcome following open heart surgery and experimental studies have demonstrated that glucose-insulin-potassium (GIK) infusion exerts cardioprotective effects by reducing myocardial ischemia-reperfusion injuries. This randomized controlled trial was designed to assess the effects of GIK on left ventricular function in moderate-to-high risk patients undergoing on-pump isolated coronary artery bypass surgery (CABGS), or combined with aortic valve replacement. The primary outcomes were the effects of GIK on two- and three-dimensional left ventricular ejection fraction (2D and 3D-LVEF), and on transmitral flow propagation velocity (Vp), that occurred between the pre- and post-CPB periods. GIK administration was associated with favorable interaction effects (p < 0.001) on 2D-LVEF, 3D-LVEF and Vp changes over the study periods. In GIK pretreated patients (N = 54), 2-D and 3D-LVEF and Vp increased slightly during surgery (mean difference [MD] + 3.5%, 95% confidence interval [95% CI] - 0.2 to 7.1%, MD + 4.0%, 95% CI 0.6-7.4%, and MD + 22.2%, 95% CI 16.0-28.4%, respectively). In contrast, in the Placebo group (N = 46), 2D-and 3D-LVEF, as well as Vp all decreased after CPB (MD - 7.5% [- 11.6 to - 3.4%], MD - 12.0% [- 15.2 to - 8.8%] and MD - 21.3% [- 25.7 to - 16.9%], respectively). In conclusion, the administration of GIK resulted in better preservation of systolic and diastolic ventricular function in the early period following weaning from CPB.

Glucose-insulin-potassium improves left ventricular performances after aortic valve replacement: a secondary analysis of a randomized controlled trial.

BACKGROUND: Patients with left ventricular (LV) hypertrophy may suffer ischemia-reperfusion injuries at the time of cardiac surgery with impairment in left ventricular function. Using transesophageal echocardiography (TEE), we evaluated the impact of glucose-insulin potassium (GIK) on LV performances in patients undergoing valve replacement for aortic stenosis. METHODS: In this secondary analysis of a double-blind randomized trial, moderate-to-high risk patients were assigned to receive GIK (20 IU insulin with 10 mEq KCL in 50 ml glucose 40%) or saline over 60 min upon anesthetic induction. The primary outcomes were the early changes in 2-and 3-dimensional left ventricular ejection fraction (2D and 3D-LVEF), peak global longitudinal strain (PGLS) and transmitral flow propagation velocity (Vp). RESULTS: At the end of GIK infusion, LV-FAC and 2D- and 3D-LVEF were unchanged whereas Vp (mean difference [MD + 7.9%, 95% confidence interval [CI] 3.2 to 12.5%; P <  0.001) increased compared with baseline values. After Placebo infusion, there was a decrease in LV-FAC (MD -2.9%, 95%CI - 4.8 to - 1.0%), 2D-LVEF (MD -2.0%, 95%CI - 2.8 to - 1.3%, 3D-LVEF (MD -3.0%, 95%CI - 4.0 to - 2.0%) and Vp (MD - 4.5 cm/s, 95%CI - 5.6 to - 3.3 cm/s). After cardiopulmonary bypass, GIK pretreatment was associated with preserved 2D and 3D-LVEF (+ 0.4%, 95% 95%CI - 0.8 to 1.7% and + 0.4%, 95%CI - 1.3 to 2.0%), and PGLS (- 0.9, 95%CI - 1.6 to - 0.2) as well as higher Vp (+ 5.1 cm/s, 95%CI 2.9 to 7.3), compared with baseline. In contrast, in the Placebo group, 2D-LVEF (- 2.2%, 95%CI - 3.4 to - 1.0), 3D-LVEF (- 6.0%, 95%CI - 7.8 to - 4.2), and Vp (- 7.6 cm/s, 95%CI - 9.4 to - 5.9), all decreased after bypass. CONCLUSIONS: Administration of GIK before aortic cross-clamping resulted in better preservation of systolic and diastolic ventricular function in patients with LV hypertrophy undergoing aortic valve replacement. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00788242 , registered on November 10, 2008.

Myocardial Protection by Glucose-Insulin-Potassium in Moderate- to High-Risk Patients Undergoing Elective On-Pump Cardiac Surgery: A Randomized Controlled Trial.

BACKGROUND: Low cardiac output syndrome is a main cause of death after cardiac surgery. We sought to assess the impact of glucose-insulin-potassium (GIK) to enhance myocardial protection in moderate- to high-risk patients undergoing on-pump heart surgery. METHODS: A randomized controlled trial was performed in adult patients (Bernstein-Parsonnet score >7) scheduled for elective aortic valve replacement and/or coronary artery bypass surgery. Patients were randomized to GIK (20 IU of insulin, 10 mEq of potassium chloride in 50 mL of glucose 40%) or saline infusion given over 60 minutes on anesthetic induction. The primary end point was postcardiotomy ventricular dysfunction (PCVD), defined as new/worsening left ventricular dysfunction requiring inotropic support (≥120 minutes). Secondary end points were the intraoperative changes in left ventricular function as assessed by transoesophageal echocardiography, postoperative troponin levels, cardiovascular and respiratory complications, and intensive care unit and hospital length of stay. RESULTS: From 224 randomized patients, 222 were analyzed (112 and 110 in the placebo and GIK groups, respectively). GIK pretreatment was associated with a reduced occurrence of PCVD (risk ratio [RR], 0.41; 95% confidence interval [CI], 0.25-0.66). In GIK-treated patients, the left systolic ventricular function was better preserved after weaning from bypass, plasma troponin levels were lower on the first postoperative day (2.9 ng·mL(-) [interquartile range {IQR}, 1.5-6.6] vs 4.3 ng·mL(-) [IQR, 2.4-8.2]), and cardiovascular (RR, 0.69; 95% CI, 0.50-0.89) and respiratory complications (RR, 0.5; 95% CI, 0.38-0.74) were reduced, along with a shorter length of stay in intensive care unit (3 days [IQR, 2-4] vs 3.5 days [IQR, 2-7]) and in hospital (14 days [IQR, 11-18.5] vs 16 days [IQR, 12.5-23.5]), compared with placebo-treated patients. CONCLUSIONS: GIK pretreatment was shown to attenuate PCVD and to improve clinical outcome in moderate- to high-risk patients undergoing on-pump cardiac surgery.

Impact of intrathecal morphine analgesia on the incidence of pulmonary complications after cardiac surgery: a single center propensity-matched cohort study.

BACKGROUND: Acute pain and systemic opioids may both negatively impact respiratory function after cardiac surgery. This study analyzes the local practice of using intrathecal morphine analgesia (ITMA) with minimal parenteral opioid administration in cardiac surgery, specifically the impact on postoperative pulmonary complications (PPCs). METHODS: Data from adult patients who underwent elective cardiac surgery between January 2002, and December 2013 in a single center were analyzed. Propensity scores estimating the likelihood of receiving ITMA were used to match (1:1) patients with ITMA and patients with intravenous analgesia (IVA). Primary outcome was PPCs, a composite endpoint including pneumonia, adult respiratory distress syndrome, and any type of acute respiratory failure. Secondary outcomes were in-hospital mortality, cardiovascular complications, and length of stay in the intensive care unit (ICU) and hospital. RESULTS: From a total of 1'543 patients, 920 were treated with ITMA and 623 with IVA. No adverse event consequent to the spinal puncture was reported. Propensity score matching created 557 balanced pairs. The occurrence of PPCs in patients with ITMA was 8.1% vs. 12.8% in patients with IVA (odds ratio, 0.6; 95% CI, 0.40-0.89; p = 0.012). Fewer patients with ITMA had a prolonged stay in the ICU (> 4 days; 16.5% vs. 21.2%, p = 0.047) or in the hospital (> 15 days; 25.5% vs. 31.8%. p = 0.024). In-hospital mortality and cardiovascular complications did not differ significantly between the two groups. CONCLUSION: In this study involving cardiac surgical patients, ITMA was safely applied and was associated with fewer PPCs.

Assessment of Haemostasis in patients undergoing emergent neurosurgery by rotational Elastometry and standard coagulation tests: a prospective observational study.

BACKGROUND: Rotational elastometry (ROTEM) has been shown useful to monitor coagulation in trauma patients and in major elective surgery. In this study, we aimed to evaluate the utility of ROTEM to identify hemostatic disturbances and to predict the need for transfusion, compared with standard coagulation tests (SCTs) in patients undergoing emergent neurosurgery. METHODS: Over a four-year period, adult patients who met criteria for emergent neurosurgery lasting more than 90 min were included in the study. Blood was collected preoperatively and analyzed with SCTs (international normalized ratio [INR], fibrinogen concentration, prothrombin time [PT or Quick], partial thromboplastine time [PTT], fibrinogen concentration and platelet count), and ROTEM assays. Correlations between SCTs and ROTEM parameters as well as receiver operating characteristic curves were performed to detect a coagulopathic pattern based on standard criteria and the need for transfusing at least 3 units of packed red blood cells (PRBCs). RESULTS: In a cohort of 92 patients, 39 (42%) required ≥3 PRBCs and a coagulopathic pattern was identified in 32 patients based on SCTs and in 19 based on ROTEM. There was a strong correlation between PTT and INTEM coagulation time (R = 0.76) as well as between fibrinogen concentrations and FIBTEM maximal clot firmess (R = 0.70). The need for transfusion (≥ 3 PRBCs) was best predicted by the maximal clot firmess of EXTEM and FIBTEM (AUC of 0.72 and 0.71, respectively) and by fibrinogen concentration (AUC of 0.70). CONCLUSIONS: In patients undergoing emergent neurosurgery, ROTEM analysis provides valid markers of early coagulopathy and predictors of blood transfusion requirements.

Multimodality imaging evaluation of a mitro-aortic fibrosa pseudoaneurysm fistulizing into both atria.

To our knowledge, we describe the first case of a pseudoaneurysm of the mitro-aortic intervalvular fibrosa fistulizing into both atria, following an aortic bacterial endocarditis and valve replacement.

Impact of early haemodynamic goal-directed therapy in patients undergoing emergency surgery: an open prospective, randomised trial.

Haemodynamic goal-directed therapies (GDT) may improve outcome following elective major surgery. So far, few data exist regarding haemodynamic optimization during emergency surgery. In this randomized, controlled trial, 50 surgical patients with hypovolemic or septic conditions were enrolled and we compared two algorithms of GDTs based either on conventional parameters and pressure pulse variation (control group) or on cardiac index, global end-diastolic volume index and stroke volume variation as derived from the PiCCO monitoring system (optimized group). Postoperative outcome was estimated by a composite index including major complications and by the Sequential Organ Failure Assessment (SOFA) Score within the first 3 days after surgery (POD1, POD2 and POD3). Data from 43 patients were analyzed (control group, N = 23; optimized group, N = 20). Similar amounts of fluid were given in the two groups. Intraoperatively, dobutamine was given in 45 % optimized patients but in no control patients. Major complications occurred more frequently in the optimized group [19 (95 %) versus 10 (40 %) in the control group, P < 0.001]. Likewise, SOFA scores were higher in the optimized group on POD1 (10.2 ± 2.5 versus 6.6 ± 2.2 in the control group, P = 0.001), POD2 (8.4 ± 2.6 vs 5.0 ± 2.4 in the control group, P = 0.002) and POD 3 (5.2 ± 3.6 and 2.2 ± 1.3 in the control group, P = 0.01). There was no significant difference in hospital mortality (13 % in the control group and 25 % in the optimized group). Haemodynamic optimization based on volumetric and flow PiCCO-derived parameters was associated with a less favorable postoperative outcome compared with a conventional GDT protocol during emergency surgery.

Effective Apixaban removal using hemoadsorption during emergent open-heart surgery: a case report and narrative literature review.

BACKGROUND: The management of hemostasis in patients medicated with apixaban (Eliquis) undergoing emergency cardiac surgery is exceedingly difficult. The body's natural elimination pathways for apixaban prove ineffective in emergency situations, and the impact of hemodialysis is limited. The application of Cytosorb® may attenuate the concentration of apixaban, thereby facilitating the stabilization of these patients. CASE PRESENTATION: An 84-year-old man treated with apixaban, underwent emergency ascending aorta replacement surgery due to an acute type A aortic dissection. To address the challenges induced by apixaban, we integrated Cytosorb® cartridge into the Cardiopulmonary bypass circuit. There was a 63.7% decrease in perioperative apixaban-specific anti-factor Xa activity. The patient's postoperative course was favourable. CONCLUSION: Hemoadsorption with Cytosorb® may offers a safe and feasible approach for reducing apixaban concentration in emergency cardiac surgery, thereby mitigating the risk of hemorrhagic complications.

Cardioprotection with glucose insulin potassium (GIK) during non cardiac surgery in a patient with stress induced myocardial ischemia: A case report.

The administration of glucose-insulin-potassium (GIK) has demonstrated cardioprotective effects in cardiac surgery. A 58-year-old male with severe disabling back pain due to posterolateral lumbar pseudarthrosis was scheduled for spine surgery. He previously experienced two episodes of acute coronary syndrome that required percutaneous coronary interventions (PCIs). Coronary angiogram showed intrastent occlusions and multiple coronary lesions that were not suitable for percutaneous or surgical revascularization. During pharmacological stress imaging, myocardial ischemia developed in 19% of the ventricular mass and was reduced to 7% when GIK was administered. After anesthesia induction, the GIK solution was also infused and surgery was uneventful, with no signs of postoperative myocardial injury. Four days later, the patient was successfully discharged to a rehabilitation center. This is the first clinical report of GIK pretreatment during non-cardiac surgery in a patient with ischemic heart disease (IHD).

Myocardial injury after major noncardiac surgery: A secondary analysis of a randomized controlled trial.

BACKGROUND: Myocardial injury after noncardiac surgery frequently occurs and may influence survival. The aims of this study were to examine the association between myocardial injury after noncardiac surgery and patient and procedural factors as well as its impact on postoperative clinical outcome. METHODS: A retrospective analysis was conducted from data collected in adults enrolled in a randomized trial in elective major open abdominal surgery. Preoperative patient characteristics, intraoperative hemodynamic changes, and postoperative adverse events were analyzed, and Kaplan-Meier curves were built for postoperative survival probability. After adjustment for baseline patient and procedural characteristics, the effect of myocardial injury after noncardiac surgery on postoperative outcomes was analyzed in a propensity score matched cohort. RESULTS: Among 394 patients, myocardial injury after noncardiac surgery was reported in 109 (27.7%) and was associated with a higher cardiovascular risk profile, prolonged surgery (333 ± 111 min vs 295 ± 134 min, P = .010), greater need for transfusions (41.3% vs 19.3%, P < .001), higher incidence of major adverse cardiac events (22.9% vs 6.7%, P < .001), pulmonary complications (31.2% vs 17.9%, P = .004) , acute kidney injury (30.3% vs 18.2%, P = .009), and systemic inflammatory syndrome (28.4% vs 13.0%, P < .001). After propensity score matching, the operative time and the need for blood transfusion remained higher among myocardial injury after noncardiac surgery patients who experienced more frequent major adverse cardiac events and acute kidney injury. In both the entire and matched cohorts, survival up to 30 months after surgery was determined mainly by the presence of cancer. CONCLUSION: The burden of cardiovascular disease and operative stress surgery is predictive of myocardial injury after noncardiac surgery and, in turn, with a higher incidence of cardiac adverse events, whereas the presence of cancer is associated with poor survival in patients undergoing major open abdominal surgery. Further studies are needed to determine whether myocardial injury after noncardiac surgery can be prevented by better control of the patient's cardiovascular condition and implementation of less invasive of surgical procedures.

Chronic ß blockade is associated with a better outcome after elective noncardiac surgery than acute ß blockade: a single-center propensity-matched cohort study.

BACKGROUND: Current guidelines on perioperative care recommend the prophylactic use of ß blockers in high-risk patients undergoing noncardiac surgery. However, recent studies show that, in some instances, perioperative ß blockade can cause harm. Furthermore, chronic ß blockade, titrated to effect before surgery, may be superior to acute perioperative ß blockade. The primary objective of this study was to compare major acute cardiac outcomes in patients who underwent surgery with chronic ß blocker therapy with those in patients with acute ß-blocker therapy. METHODS: Data were collected for 10,691 consecutive patients undergoing elective noncardiac surgery between April 1, 2008, and April 30, 2010. Propensity scores, estimating the probability of receiving a preoperative ß blocker, were calculated to match (1:1) the patients with acute and chronic ß-blocker therapy. The primary outcome was a composite of myocardial infarction, nonfatal cardiac arrest, and perioperative mortality. The rate of cardiac events was compared in the matched cohorts. RESULTS: A total of 962 patients were chronically treated with a ß blocker before surgery; in 436 patients, the ß blocker was administrated acutely. Propensity score matching created 301 patient pairs who were well-balanced for major comorbidities, concomitant drug use, and type of surgery. The primary outcome was observed in 9 (3.0%) chronic versus 24 (8.0%) acute ß-blocked patients (relative risk, 2.67; 95% CI, 1.27-5.60; P = 0.011). CONCLUSIONS: Acute ß blockade, initiated within the first 2 days after surgery, was associated with worse cardiac outcome compared with a matched cohort of patients who underwent surgery on chronic ß blockade. These results should be validated in a larger prospective trial.

The hypoxic pulmonary vasoconstriction: From physiology to clinical application in thoracic surgery.

More than 70 years after its original report, the hypoxic pulmonary vasoconstriction (HPV) response continues to spark scientific interest on its mechanisms and clinical implications, particularly for anesthesiologists involved in thoracic surgery. Selective airway intubation and one-lung ventilation (OLV) facilitates the surgical intervention on a collapsed lung while the HPV redirects blood flow from the "upper" non-ventilated hypoxic lung to the "dependent" ventilated lung. Therefore, by limiting intrapulmonary shunting and optimizing ventilation-to-perfusion (V/Q) ratio, the fall in arterial oxygen pressure (PaO2) is attenuated during OLV. The HPV involves a biphasic response mobilizing calcium within pulmonary vascular smooth muscles, which is activated within seconds after exposure to low alveolar oxygen pressure and that gradually disappears upon re-oxygenation. Many factors including acid-base balance, the degree of lung expansion, circulatory volemia as well as lung diseases and patient age affect HPV. Anesthetic agents, analgesics and cardiovascular medications may also interfer with HPV during the perioperative period. Since HPV represents the homeostatic mechanism for regional ventilation-to-perfusion matching and in turn, for optimal pulmonary oxygen uptake, a clear understanding of HPV is clinically relevant for all anesthesiologists.

How can we minimize the risks by optimizing patient's condition shortly before thoracic surgery?

The "moderate-to-high-risk" surgical patient is typically older, frail, malnourished, suffering from multiple comorbidities and presenting with unhealthy life style such as smoking, hazardous drinking and sedentarity. Poor aerobic fitness, sarcopenia and "toxic" behaviors are modifiable risk factors for major postoperative complications. The physiological challenge of lung cancer surgery has been likened to running a marathon. Therefore, preoperative patient optimization or " prehabilitation " should become a key component of improved recovery pathways to enhance general health and physiological reserve prior to surgery. During the short preoperative period, the patients are more receptive and motivated to adhere to behavioral interventions (e.g., smoking cessation, weaning from alcohol, balanced food intake and active mobilization) and to follow a structured exercise training program. Sufficient protein intake should be ensured (1.5-2 g/kg/day) and nutritional defects should be corrected to restore muscle mass and strength. Currently, there is strong evidence supporting the effectiveness of various modalities of physical training (endurance training and/or respiratory muscle training) to enhance aerobic fitness and to mitigate the risk of pulmonary complications while reducing the hospital length of stay. Multimodal interventions should be individualized to the patient's condition. These bundle of care are more effective than single or sequential intervention owing to synergistic benefits of education, nutritional support and physical training. An effective prehabilitation program is necessarily patient-centred and coordinated among health care professionals (nurses, primary care physician, physiotherapists, nutritionists) to help the patient regain some control over the disease process and improve the physiological reserve to sustain surgical stress.

Restricted, optimized or liberal fluid strategy in thoracic surgery: A narrative review.

Perioperative fluid balance has a major impact on clinical and functional outcome, regardless of the type of interventions. In thoracic surgery, patients are more vulnerable to intravenous fluid overload and to develop acute respiratory distress syndrome and other complications. New insight has been gained on the mechanisms causing pulmonary complications and the role of the endothelial glycocalix layer to control fluid transfer from the intravascular to the interstitial spaces and to promote tissue blood flow. With the implementation of standardized processes of care, the preoperative fasting period has become shorter, surgical approaches are less invasive and patients are allowed to resume oral intake shortly after surgery. Intraoperatively, body fluid homeostasis and adequate tissue oxygen delivery can be achieved using a normovolemic therapy targeting a "near-zero fluid balance" or a goal-directed hemodynamic therapy to maximize stroke volume and oxygen delivery according to the Franck-Starling relationship. In both fluid strategies, the use of cardiovascular drugs is advocated to counteract the anesthetic-induced vasorelaxation and maintain arterial pressure whereas fluid intake is limited to avoid cumulative fluid balance exceeding 1 liter and body weight gain (~1-1.5 kg). Modern hemodynamic monitors provide valuable physiological parameters to assess patient volume responsiveness and circulatory flow while guiding fluid administration and cardiovascular drug therapy. Given the lack of randomized clinical trials, controversial debate still surrounds the issues of the optimal fluid strategy and the type of fluids (crystalloids versus colloids). To avoid the risk of lung hydrostatic or inflammatory edema and to enhance the postoperative recovery process, fluid administration should be prescribed as any drug, adapted to the patient's requirement and the context of thoracic intervention.