The frail patient undergoing cardiac surgery: lessons learned and future perspectives.

Frailty is a geriatric condition characterized by the reduction of the individual's homeostatic reserves. It determines an increased vulnerability to endogenous and exogenous stressors and can lead to poor outcomes. It is an emerging concept in perioperative medicine, since an increasing number of patients undergoing surgical interventions are older and the traditional models of care seem to be inadequate to satisfy these patients' emerging clinical needs. Nowadays, the progressive technical and clinical improvements allow to offer cardiac operations to an older, sicker and frail population. For these reasons, a multidisciplinary team involving cardiac surgeons, clinical cardiologists, anesthesiologists, and geriatricians, is often needed to assess, select and provide tailored care to these high-risk frail patients to optimize clinical outcomes. There is unanimous agreement that frailty assessment may capture the individual's biological decline and the heterogeneity in risk profile for poor health-related outcomes among people of the same age. However, since commonly used preoperative scores for cardiac surgery fail to capture frailty, a specific preoperative assessment with dedicated tools is warranted to correctly recognize, measure and quantify frailty in these patients. On the contrary, pre-operative and post-operative interventions can reduce the risk of complications and support patient recovery promoting surgical resilience. Minimally invasive cardiac procedures aim to reduce surgical trauma and may be associated with better clinical outcome in this specific sub-group of high-risk patients. Among postoperative adverse events, the occurrence of delirium represents a risk factor for several unfavorable outcomes including mortality and subsequent cognitive decline. Its presence should be carefully recognized, triggering an adequate, evidence based, treatment. There is evidence, from several cross-section and longitudinal studies, that frailty and delirium may frequently overlap, with frailty serving both as a predisposing factor and as an outcome of delirium and delirium being a marker of a latent condition of frailty. In conclusion, frail patients are at increased risk to experience poor outcome after cardiac surgery. A multidisciplinary approach aimed to recognize more vulnerable individuals, optimize pre-operative conditions, reduce surgical invasivity and improve post-operative recovery is required to obtain optimal long-term outcome.

Arterio-venous fistula causing acute right heart failure: A rare complication of veno-arterial extracorporeal membrane oxygenation.

Introduction: Vascular complications are a major issue in V-A ECMO and can affect long term outcome. Among these, Artero-Venous (AV) fistulas may lead to right heart failure.Case History: A 73-years patient supported with V-A ECMO for post-cardiotomy biventricular failure developed right heart failure after V-A ECMO decannulation, requiring V-A ECMO recannulation. The presence of an AV femoral fistula was incidentally revealed during femoral vein cannulation, from which oxygenated blood was unexpectedly drawn. The angiographic assessment confirmed the presence of a fistula between superficial femoral artery and vein, at the site of the first venous ECMO cannulation. This was caused by the venous cannula that inadvertently passed across the artery and created an AV fistula that was opened by the venous cannula removal. The exclusion of the endovascular fistula allowed the right heart failure resolution.Conclusions: In the presence of right heart failure after recent vascular manipulation, AV fistula should be ruled out.

Angiotensin-(1-7) improves oxygenation, while reducing cellular infiltrate and fibrosis in experimental Acute Respiratory Distress Syndrome.

BACKGROUND: The renin-angiotensin system (RAS) plays a role in the pathogenesis of ARDS, Angiotensin II (Ang-II) contributing to the pathogenesis of inflammation and fibrogenesis. Angiotensin-(1-7) (Ang-(1-7)) may antagonize the effects of Ang-II. This study was aimed at evaluating the potential for Ang-(1-7) to reduce injury, inflammation and fibrosis in an experimental model of ARDS in the acute and late phases. METHODS: Male Sprague Dawley rats underwent an instillation of 0.1 M hydrochloric acid (HCl, 2.5 ml/kg) into the right bronchus. In an acute ARDS study, acid-injured rats were subjected to high stretch mechanical ventilation (18 ml/kg) for 5 h and randomized to receive an intravenous infusion of either vehicle (saline), Ang-(1-7) at low dose(0.27 µg/kg/h) (ALD), or high dose (60 µg/kg/h) (AHD) starting simultaneously with injury or 2 h afterwards. Arterial blood gas analysis and bronchoalveolar lavage (BAL) were performed to assess the injury. For the late ARDS study, after HCl instillation rats were randomized to either vehicle or high dose Ang-(1-7) (300 µg/kg/day) infused by mini osmotic pumps for two weeks, and lung hydroxyproline content measured. RESULTS: In the acute ARDS study, Ang-(1-7) led to a significant improvement in oxygenation (PaO2/FiO2 : vehicle 359 ± 86; ALD 436 ± 72; AHD 44 442 ± 56; ANOVA p = 0.007) and reduced white blood cells counts (vehicle 4,519 ± 2,234; ALD 2,496 ± 621; AHD 2,744 ± 119/mm(3); ANOVA p = 0.004). Only treatment with high dose Ang-(1-7) reduced inflammatory cell numbers in BAL (vehicle 127 ± 34; AHD 96 ± 34/ µl; p = 0.033). Interestingly also delayed administration of Ang-(1-7) was effective in reducing injury. In later ARDS, Ang-(1-7) decreased hydroxyproline content (649 ± 202 and 1,117 ± 297 µg/lung; p < 0.05). CONCLUSIONS: Angiotensin-(1-7), decreased the severity of acute lung injury and inflammation induced by combined acid aspiration and high stretch ventilation. Furthermore, continuous infusion of Ang-(1-7) reduced lung fibrosis 2 weeks following acid aspiration injury. These results call for further research on Ang-(1-7) as possible therapy for ARDS.

The effects of exogenous surfactant treatment in a murine model of two-hit lung injury.

BACKGROUND: Because pulmonary endogenous surfactant is altered during acute respiratory distress syndrome, surfactant replacement may improve clinical outcomes. However, trials of surfactant use have had mixed results. We designed this animal model of unilateral (right) lung injury to explore the effect of exogenous surfactant administered to the injured lung on inflammation in the injured and noninjured lung. METHODS: Mice underwent hydrochloric acid instillation (1.5 mL/kg) into the right bronchus and prolonged (7 hours) mechanical ventilation (25 mL/kg). After 3 hours, mice were treated with 1 mL/kg exogenous surfactant (Curosurf®) (surf group) or sterile saline (NaCl 0.9%) (vehicle group) in the injured (right) lung or did not receive any treatment (hydrochloric acid, ventilator-induced lung injury). Gas exchange, lung compliance, and bronchoalveolar inflammation (cells, albumin, and cytokines) were evaluated. After a significant analysis of variance (ANOVA) test, Tukey post hoc test was used for statistical analysis. RESULTS: At least 8 to 10 mice in each group were analyzed for each evaluated variable. Surfactant treatment significantly increased both the arterial oxygen tension to fraction of inspired oxygen ratio and respiratory system static compliance (P = 0.027 and P = 0.007, respectively, for surf group versus vehicle). Surfactant therapy increased indices of inflammation in the acid-injured lung compared with vehicle: inflammatory cells (685 [602-773] and 216 [125-305] × 1000/mL, respectively; P < 0.001) and albumin in bronchoalveolar lavage (BAL) (1442 ± 588 and 743 ± 647 µg/mL, respectively; P = 0.027). These differences were not found (P = 0.96 and P = 0.54) in the contralateral (uninjured) lung (inflammatory cells 131 [78-195] and 119 [87-149] × 1000/mL and albumin 135 ± 100 and 173 ± 115 µg/mL). CONCLUSIONS: Exogenous surfactant administration to an acid-injured right lung improved gas exchange and whole respiratory system compliance. However, markers of inflammation increased in the right (injured) lung, although this result was not found in the left (uninjured) lung. These data suggest that the mechanism by which surfactant improves lung function may involve both uninjured and injured alveoli.

Pulmonary surfactant synthesis after unilateral lung injury in mice.

Aspiration pneumonitis can lead to alveolar surfactant dysfunction. We employed a murine model of unilateral aspiration to compare surfactant synthesis in the injured (I) and noninjured (NI) contralateral lung. Mice were instilled with hydrochloric acid in the right bronchus and, after 18 h, an intraperitoneal dose of deuterated water was administered as precursor of disaturated phosphatidylcholine (DSPC)-palmitate. Selected bronchoalveolar lavage fluid (BALF) was collected at scheduled time points and lungs were removed. We measured DSPC-palmitate synthesis in lung tissue and secretion in BALF by gas chromatography-isotope ratio mass spectrometry, together with total proteins and myeloperoxidase activity (MPO) by spectrophotometry. BALF total proteins and MPO were significantly increased in the I lungs compared with NI and naïve control lungs. The DSPC pool size was significantly lower in the BALF of the I lungs compared with naïve controls. DSPC synthesis was accelerated in the I and NI lungs. DSPC secretion of the I lungs was similar to their respective naïve controls, and it was markedly lower compared with their respective NI contralateral lungs. DSPC synthesis and secretion were faster, especially in the NI lungs, compared with naïve control lungs, as a possible compensatory mechanism due to a cross-talk between the lungs triggered by inflammation, hyperventilation, and/or undetermined type II cell reaction to the injury.

Unilateral acid aspiration augments the effects of ventilator lung injury in the contralateral lung.

BACKGROUND: Mechanical ventilation is necessary during acute respiratory distress syndrome, but it promotes lung injury because of the excessive stretch applied to the aerated parenchyma. The authors' hypothesis was that after a regional lung injury, the noxious effect of mechanical ventilation on the remaining aerated parenchyma would be more pronounced. METHODS: Mice, instilled with hydrochloric acid (HCl) in the right lung, was assigned to one of the following groups: mechanical ventilation with tidal volumes (VT) 25 ml/kg (HCl-VILI25, n = 12), or VT 15 ml/kg (HCl-VILI15, n = 9), or spontaneous breathing (HCl-SB, n = 14). Healthy mice were ventilated with VT 25 ml/kg (VILI25, n = 11). Arterial oxygenation, lung compliance, bronchoalveolar lavage inflammatory cells, albumin, and cytokines concentration were measured. RESULTS: After 7 h, oxygenation and lung compliance resulted lower in HCl-VILI25 than in VILI25 (P < 0.05, 210 ± 54 vs. 479 ± 83 mmHg, and 32 ± 3.5 vs. 45 ± 4.1 µl/cm H2O, mean ± SD, respectively). After right lung injury, the left lung of HCl-VILI25 group received a greater fraction of the VT than the VILI25 group, despite an identical global VT. The number of total and polymorphonuclear cells in bronchoalveolar lavage resulted significantly higher in HCl-VILI25, compared with the other groups, in not only the right lung, but also in the left lung. The albumin content in the left lung resulted higher in HCl-VILI25 than in VILI25 (224 ± 85 vs. 33 ± 6 µg/ml; P < 0.05). Cytokines levels did not differ between groups. CONCLUSION: Aggressive mechanical ventilation aggravates the preexisting lung injury, which is noxious for the contralateral, not previously injured lung, possibly because of a regional redistribution of VT.

Time course of metabolic activity and cellular infiltration in a murine model of acid-induced lung injury.

PURPOSE: This study investigates whether positron emission tomography (PET) can be used to monitor the inflammatory response and its correlation with the later fibroproliferative phase in an experimental model of acute lung injury. METHODS: Hydrochloric acid (0.1 N, pH 1, 1.5 ml/kg) was instilled into the right bronchus of mice. A group of mice underwent a micro-computed tomography (CT) scan 1 h after lung injury and a series of 2-[(18)F]fluorine-2-deoxy-D: -glucose (FDG)-PET scans (6, 24 and 48 h and 7 days after surgery). After 21 days respiratory static compliance was assessed and lung tissue was collected in order to measure the hydroxy (OH)-proline content. Other groups of mice underwent micro-CT and micro-PET scans at the same time points, and then were immediately killed to assess arterial blood gases and histology. RESULTS: Histological analysis showed the recruitment of neutrophils and macrophages into the damaged lung, reaching the peak at 24 and 48 h, respectively. The time course of the [(18)F]FDG signal, used as a marker of inflammation, correlated with that of recruited inflammatory cells. In mice killed 21 days after the surgery, a correlation was found between reduced respiratory static compliance and high PET signal 7 days after lung injury. The PET signal also correlated with the OH-proline content. CONCLUSIONS: This study demonstrated that PET imaging is a valid means of tracking the inflammatory response, also in longitudinal studies. Moreover, a correlation was found between persistence of the inflammatory response and fibrotic evolution of the injury.

The effect of a single bolus of exogenous surfactant on lung compliance persists until two weeks after treatment in a model of acid aspiration pneumonitis.

Aspiration pneumonitis, a direct cause of acute lung injury, is associated to a severe deterioration of lung function due in part to endogenous surfactant system impairment. We evaluated the effects of selective exogenous surfactant administration in a murine model of acid-induced lung injury both at short and long term. Hydrochloric acid was instilled into the right bronchus of the mice (0.1 M, 1.5 ml/kg). Six hours from acid instillation, they received, in the injured lung, a 1 ml/kg bolus of porcine surfactant (Curosurf®) 40 or 80 mg phospholipids/ml (Surf40 or Surf80), or saline (0.9% NaCl, vehicle) Functional, biochemical, histological and inflammatory results were obtained 24 h after injury. In the Surf80 and vehicle group, lung mechanics and histology were assessed again after two weeks. Micro-Computed Tomography scans were performed at 24 h and two weeks. 24 h after injury in the Surf80 group respiratory system compliance and oxygenation were significantly improved compared to the vehicle, while neutrophilic fraction in bronchoalveolar lavage was significantly lower. Surfactant-treated mice maintained a better compliance and a significantly reduced inflammatory infiltrate also two weeks after treatment compared to vehicle. Micro-Computed Tomography scan suggested a more pronounced reduction of injury in surfactant-treated animals two weeks after injury (p = 0.09). We showed a beneficial effect on lung function of a single bolus of exogenous surfactant in unilateral acid-induced lung injury up to two weeks after treatment. Our results may suggest a role of surfactant replacement in modulating spontaneous evolution of injury.

Regulation of leukocyte recruitment by the long pentraxin PTX3.

Pentraxins are a superfamily of conserved proteins involved in the acute-phase response and innate immunity. Pentraxin 3 (PTX3), a prototypical member of the long pentraxin subfamily, is a key component of the humoral arm of innate immunity that is essential for resistance to certain pathogens. A regulatory role for pentraxins in inflammation has long been recognized, but the underlying mechanisms remain unclear. Here we report that PTX3 bound P-selectin and attenuated neutrophil recruitment at sites of inflammation. PTX3 released from activated leukocytes functioned locally to dampen neutrophil recruitment and regulate inflammation. Antibodies have glycosylation-dependent regulatory effect on inflammation. Therefore, PTX3, which is an essential component of humoral innate immunity, and immunoglobulins share functional outputs, including complement activation, opsonization and, as shown here, glycosylation-dependent regulation of inflammation.

Lung injury and recovery in a murine model of unilateral acid aspiration: functional, biochemical, and morphologic characterization.

BACKGROUND: Acid aspiration is a complication of general anesthesia. Most animal models developed to define its pathophysiology have focused on the acute (< or =24 h) phase of the injury. The authors describe a model of acid aspiration allowing the study of this type of lung injury over time. METHODS: The authors instilled hydrochloric acid (0.1 m, 1.5 ml/kg) or normal saline in the right bronchus of mice. Lung injury was evaluated at 6 h, 12 h, 24 h, and 2 weeks by assessing arterial blood gases, respiratory system compliance, lung wet weight normalized by body weight, lung myeloperoxidase activity, and histology. Twelve hours and 2 weeks after injury, a computed tomography scan was obtained. RESULTS: In the hydrochloric acid group, arterial oxygen tension decreased (P < 0.05) at 12 and 24 h, whereas it recovered at 2 weeks; respiratory system compliance was lower both at 24 h and 2 weeks (P < 0.05). Lung weight increased at 12 and 24 h (P < 0.05). Myeloperoxidase activity peaked between 6 and 12 h. Computed tomography at 12 h showed that almost 30% of the injured lung was abnormally aerated. Although reduced, the abnormalities were still present at 2 weeks as confirmed by a fibrotic scar well evident at histologic examination. CONCLUSION: The authors characterized a murine model of regional acid aspiration allowing long-term survival. Despite a partial recovery, at 2 weeks the injury persisted, with evidence of fibrosis and lung compliance reduction. This long-term, low-mortality model seems suitable for assessment of the effects of different therapies on lung injury and repair.