Transoesophageal Doppler Monitoring For Fluid And Hemodynamic Treatment During Lung Surgery

Introduction: Patients undergoing lung resection are vulnerable to fluid overhydration. Recently, goal-directed fluid therapy using transoesophageal Doppler monitoring (TDM) has been shown to improve postoperative clinical outcome. The aim of this study was to assess the feasibility of TDM during open-chest procedures for guiding fluid and hemodynamic treatment. Methods: We performed an observational prospective study including 127 high-risk patients undergoing lung cancer resection. A restrictive fluid strategy was targeted to achieve a stroke volume index (SVI) ≥ 30ml/min/m2. Besides standard hemodynamic measurements, stroke volume index (SVI), corrected flow time (FTc), maximal acceleration (MA) and velocity (PV) were recorded during two-lung ventilation (TLV) and one-lung ventilation (OLV). Results: Doppler flow tracings could not be obtained in 4 patients during TLV (3.1%) and in 6 patients during OLV (4.9%). Preoperatively, 96 pts had SVI ≥ 30ml/min/m2 (N-SVI group) whereas 21 patients had SVI < 30ml/min/m2 (L-SVI group) associated with lower FTc values. After OLV, SVI transiently decreased (−17 ± 9%; P<0.05) in the N-SVI group whereas in the L-SVI group, SVI increased steadily until the end of surgery (+40 ± 12%). Other flow-related parameters as well as heart rate and mean arterial pressure remained unchanged. Surgical and medical characteristics did not differ between the two groups, except that larger volumes of colloids were administered intraoperatively in the L-SVI group (+2.2 ± 0.6ml/min/h compared with N-SVI group, P < 0.05). Conclusion: In thoracic surgical patients, TDM can be used to detect and correct low flow conditions and to guide hemodynamic support during the intraoperative perio

Impact of intraoperative lung-protective interventions in patients undergoing lung cancer surgery

INTRODUCTION: In lung cancer surgery, large tidal volume and elevated inspiratory pressure are known risk factors of acute lung (ALI). Mechanical ventilation with low tidal volume has been shown to attenuate lung injuries in critically ill patients. In the current study, we assessed the impact of a protective lung ventilation (PLV) protocol in patients undergoing lung cancer resection. METHODS: We performed a secondary analysis of an observational cohort. Demographic, surgical, clinical and outcome data were prospectively collected over a 10-year period. The PLV protocol consisted of small tidal volume, limiting maximal pressure ventilation and adding end-expiratory positive pressure along with recruitment maneuvers. Multivariate analysis with logistic regression was performed and data were compared before and after implementation of the PLV protocol: from 1998 to 2003 (historical group, n = 533) and from 2003 to 2008 (protocol group, n = 558). RESULTS: Baseline patient characteristics were similar in the two cohorts, except for a higher cardiovascular risk profile in the intervention group. During one-lung ventilation, protocol-managed patients had lower tidal volume (5.3 +/- 1.1 vs. 7.1 +/- 1.2 ml/kg in historical controls, P = 0.013) and higher dynamic compliance (45 +/- 8 vs. 32 +/- 7 ml/cmH2O, P = 0.011). After implementing PLV, there was a decreased incidence of acute lung injury (from 3.7% to 0.9%, P < 0.01) and atelectasis (from 8.8 to 5.0, P = 0.018), fewer admissions to the intensive care unit (from 9.4% vs. 2.5%, P < 0.001) and shorter hospital stay (from 14.5 +/- 3.3 vs. 11.8 +/- 4.1, P < 0.01). When adjusted for baseline characteristics, implementation of the open-lung protocol was associated with a reduced risk of acute lung injury (adjusted odds ratio of 0.34 with 95% confidence interval of 0.23 to 0.75; P = 0.002). CONCLUSIONS: Implementing an intraoperative PLV protocol in patients undergoing lung cancer resection was associated with improved postoperative respiratory outcomes as evidence by significantly reduced incidences of acute lung injury and atelectasis along with reduced utilization of intensive care unit resources

Incidence, risk factors and prognosis of changes in serum creatinine early after aortic abdominal surgery

Objective: To determine the incidence, risk factors, and prognostic implications of serum creatinine changes following major vascular surgery. Design: Observational study. Settings: University hospital. Patients: Cohort of 599 consecutive patients undergoing elective abdominal aortic surgery. Interventions: Review of prospectively collected data from 1993 to 2004. Measurements and results: The receiver-operator characteristic (ROC) curve analysis was used to detect the best threshold for postoperative elevation in serum creatinine (Δ Creat) in relation to major complications. Acut-off value of +0.5 mg/dl was selected to define renal dysfunction (RD0.5 group, n = 91; no RD0.5, n = 508) that was associated with higher mortality (7.7% in RD0.5 group vs 1.4% in no RD0.5 group, P  40 min; OR, 3.8, 95% CI, 1.9-7.2), blood transfusion (> 5 units; OR, 1.9, 95% CI 1.2-6.1), and rhabdomyolysis (OR, 3.6, 95% CI 1.7-7.9). Conclusions: Postoperative RD0.5 (Δ Creat  > 0.5 mg/dl) occurs in 15% of vascular patients and carries abad prognosis. Preoperative renal insufficiency and factors related to the complexity of surgery are the main predictors of renal dysfunctio

Preoperative diastolic function predicts the onset of left ventricular dysfunction following aortic valve replacement in high-risk patients with aortic stenosis

INTRODUCTION: Left ventricular (LV) dysfunction frequently occurs after cardiac surgery, requiring inotropic treatment and/or mechanical circulatory support. In this study, we aimed to identify clinical, surgical and echocardiographic factors that are associated with LV dysfunction during weaning from cardiopulmonary bypass (CPB) in high-risk patients undergoing valve replacement for aortic stenosis. METHODS: Perioperative data were prospectively collected in 108 surgical candidates with an expected operative mortality ≥ 9%. All anesthetic and surgical techniques were standardized. Reduced LV systolic function was defined by an ejection fraction <40%. Diastolic function of the LV was assessed using standard Doppler-derived parameters, tissue Doppler Imaging (TDI) and transmitral flow propagation velocity (Vp). RESULTS: Doppler-derived pulmonary flow indices and TDI could not be obtained in 14 patients. In the remaining 94 patients, poor systolic LV was documented in 14% (n = 12) and diastolic dysfunction in 84% of patients (n = 89), all of whom had Vp <50 cm/s. During weaning from CPB, 38 patients (40%) required inotropic and/or mechanical circulatory support. By multivariate regression analysis, we identified three independent predictors of LV systolic dysfunction: age (Odds ratio [OR] = 1.11; 95% confidence interval (CI), 1.01 to 1.22), aortic clamping time (OR = 1.04; 95% CI, 1.00 to 1.08) and Vp (OR = 0.65; 95% CI, 0.52 to 0.81). Among echocardiographic measurements, Vp was found to be superior in terms of prognostic value and reliability. The best cut-off value for Vp to predict LV dysfunction was 40 cm/s (sensitivity of 72% and specificity 94%). Patients who experienced LV dysfunction presented higher in-hospital mortality (18.4% vs. 3.6% in patients without LV dysfunction, P = 0.044) and an increased incidence of serious cardiac events (81.6 vs. 28.6%, P < 0.001). CONCLUSIONS: This study provides the first evidence that, besides advanced age and prolonged myocardial ischemic time, LV diastolic dysfunction characterized by Vp ≤ 40 cm/sec identifies patients who will require cardiovascular support following valve replacement for aortic stenosis

Effect of body position on the redistribution of regional lung aeration during invasive and non-invasive ventilation of COVID-19 patients

Severe COVID-19-related acute respiratory distress syndrome (C-ARDS) requires mechanical ventilation. While this intervention is often performed in the prone position to improve oxygenation, the underlying mechanisms responsible for the improvement in respiratory function during invasive ventilation and awake prone positioning in C-ARDS have not yet been elucidated. In this prospective observational trial, we evaluated the respiratory function of C-ARDS patients while in the supine and prone positions during invasive (n = 13) or non-invasive ventilation (n = 15). The primary endpoint was the positional change in lung regional aeration, assessed with electrical impedance tomography. Secondary endpoints included parameters of ventilation and oxygenation, volumetric capnography, respiratory system mechanics and intrapulmonary shunt fraction. In comparison to the supine position, the prone position significantly increased ventilation distribution in dorsal lung zones for patients under invasive ventilation (53.3 ± 18.3% vs. 43.8 ± 12.3%, percentage of dorsal lung aeration ± standard deviation in prone and supine positions, respectively; p = 0.014); whereas, regional aeration in both positions did not change during non-invasive ventilation (36.4 ± 11.4% vs. 33.7 ± 10.1%; p = 0.43). Prone positioning significantly improved the oxygenation both during invasive and non-invasive ventilation. For invasively ventilated patients reduced intrapulmonary shunt fraction, ventilation dead space and respiratory resistance were observed in the prone position. Oxygenation is improved during non-invasive and invasive ventilation with prone positioning in patients with C-ARDS. Different mechanisms may underly this benefit during these two ventilation modalities, driven by improved distribution of lung regional aeration, intrapulmonary shunt fraction and ventilation-perfusion matching. However, the differences in the severity of C-ARDS may have biased the sensitivity of electrical impedance tomography when comparing positional changes between the protocol groups

Changes in Hepatic Blood Flow and Liver Function during Closed Abdominal Hyperthermic Intraperitoneal Chemotherapy following Cytoreduction Surgery

Background. The increase in intra-abdominal pressure (IAP) during closed abdominal hyperthermic intraperitoneal chemotherapy (HIPEC) leads to major haemodynamic changes and potential organ dysfunction. We investigated these effects on hepatic blood flow (HBF) and liver function in patients undergoing HIPEC following cytoreductive surgery and fluid management guided by dynamic preload indices. Methods. In this prospective observational clinical study including 15 consecutive patients, we evaluated HBF by transesophageal echocardiography and liver function by determination of the indocyanine green plasma disappearance rate (ICG-PDR). Friedman’s two-way analysis of variance by ranks and Wilcoxon signed-rank test were performed for statistical analysis. Results. During HIPEC, HBF was markedly reduced, resulting in the loss of any pulsatile Doppler flow signal in all but one patient. The ICG-PDR, expressed as median (interquartile 25–75), decreased from 23 (20–30) %/min to 18 (12.5–19) %/min (p<0.001). Despite a generous crystalloid infusion rate (27 (22–35) ml/kg/h), cardiac index decreased during the increased IAP period, inferior vena cava diameter decreased, stroke volume variation and pulse pressure variation increased, lung compliance dropped, and there was an augmentation in plateau pressure. All changes were significant (p<0.001) and reversed to baseline values post HIPEC. Conclusion. Despite optimizing intravenous fluids during closed abdominal HIPEC, we observed a marked decrease in HBF and liver function. Both effects were transient and limited to the period of HIPEC but could influence the choice between closed or open abdominal cavity procedure for HIPEC and should be considered in similar clinical situations of increased IAP

TDP-43 Depletion in Microglia Promotes Amyloid Clearance but Also Induces Synapse Loss

Microglia coordinate various functions in the central nervous system ranging from removing synaptic connections, to maintaining brain homeostasis by monitoring neuronal function, and clearing protein aggregates across the lifespan. Here we investigated whether increased microglial phagocytic activity that clears amyloid can also cause pathological synapse loss. We identified TDP-43, a DNA-RNA binding protein encoded by the Tardbp gene, as a strong regulator of microglial phagocytosis. Mice lacking TDP-43 in microglia exhibit reduced amyloid load in a model of Alzheimer's disease (AD) but at the same time display drastic synapse loss, even in the absence of amyloid. Clinical examination from TDP-43 pathology cases reveal a considerably reduced prevalence of AD and decreased amyloid pathology compared to age-matched healthy controls, confirming our experimental results. Overall, our data suggest that dysfunctional microglia might play a causative role in the pathogenesis of neurodegenerative disorders, critically modulating the early stages of cognitive decline

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