Vascular relaxation of canine visceral arteries after ischemia by means of supraceliac aortic cross-clamping followed by reperfusion

<p>Abstract</p> <p>Background</p> <p>The supraceliac aortic cross-clamping can be an option to save patients with hipovolemic shock due to abdominal trauma. However, this maneuver is associated with ischemia/reperfusion (I/R) injury strongly related to oxidative stress and reduction of nitric oxide bioavailability. Moreover, several studies demonstrated impairment in relaxation after I/R, but the time course of I/R necessary to induce vascular dysfunction is still controversial. We investigated whether 60 minutes of ischemia followed by 30 minutes of reperfusion do not change the relaxation of visceral arteries nor the plasma and renal levels of malondialdehyde (MDA) and nitrite plus nitrate (NOx).</p> <p>Methods</p> <p>Male mongrel dogs (n = 27) were randomly allocated in one of the three groups: sham (no clamping, n = 9), ischemia (supraceliac aortic cross-clamping for 60 minutes, n = 9), and I/R (60 minutes of ischemia followed by reperfusion for 30 minutes, n = 9). Relaxation of visceral arteries (celiac trunk, renal and superior mesenteric arteries) was studied in organ chambers. MDA and NOx concentrations were determined using a commercially available kit and an ozone-based chemiluminescence assay, respectively.</p> <p>Results</p> <p>Both acetylcholine and calcium ionophore caused relaxation in endothelium-intact rings and no statistical differences were observed among the three groups. Sodium nitroprusside promoted relaxation in endothelium-denuded rings, and there were no inter-group statistical differences. Both plasma and renal concentrations of MDA and NOx showed no significant difference among the groups.</p> <p>Conclusion</p> <p>Supraceliac aortic cross-clamping for 60 minutes alone and followed by 30 minutes of reperfusion did not impair relaxation of canine visceral arteries nor evoke biochemical alterations in plasma or renal tissue.</p

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Effect of 15&deg; Reverse Trendelenburg Position on Arterial Oxygen Tension during Isoflurane Anesthesia in Horses

Lower than expected arterial oxygen tension (PaO2) continues to be an unresolved problem in equine anesthesia. The aim of this randomized, crossover, and prospective study using six adult horses is to determine if a 15&deg; reverse Trendelenburg position (RTP) increases PaO2 during inhalation anesthesia. Under constant-dose isoflurane anesthesia, dorsally recumbent horses were positioned either horizontally (HP) or in a 15&deg; RTP for 2 h. Lungs were mechanically ventilated (15 mL/kg, 6 breaths/min). Arterial carbon dioxide tension (PaCO2), PaO2, inspired oxygen fraction (FiO2), and end-tidal carbon dioxide tension (EtCO2) were determined every 30 min during anesthesia. Indices of dead-space ventilation (Vd/Vt), oxygenation (P&ndash;F ratio), and perfusion (F&ndash;shunt) were calculated. Dobutamine and phenylephrine were used to support mean arterial pressure (MAP). Data are presented as median and range. In one horse, which was deemed an outlier due to its thoracic dimensions and body conformation, indices of oxygenation worsened in RTP compared to HP (median PaO2 438 vs. 568 mmHg; P&ndash;F ratio 454 vs. 586 mmHg, and F&ndash;shunt 13.0 vs. 5.7 mmHg). This horse was excluded from calculations. In the remaining five horses they were significantly better with RTP compared to HP. Results in remaining five horses showed that PaO2 (502, 467&ndash;575 vs. 437, 395&ndash;445 mmHg), P-F ratio (518, 484&ndash;598 vs. 455, 407&ndash;458 mmHg), and F-shunt (10.1, 4.2&ndash;11.7 vs. 14.2, 13.8&ndash;16.0 mmHg) were significantly different between RTP and HP (p = 0.03). Other variables were not significantly different. In conclusion, the 15&deg; RTP resulted in better oxygenation than HP in dorsally recumbent, isoflurane-anesthetized horses, although worsening of oxygenation may occur in individual horses. A study detailing the cardiovascular consequences of RTP is necessary before it can be recommended for clinical practice

Glycol methacrylate-embedding medium to study morphological alterations of saphenous vein under brief and crescent pressurizations Inclusão em glicol metacrilato para estudar alterações morfológicas de veias safenas humanas submetidas a pressurizações breves e crescentes

PURPOSE: This study sought to evaluate the efficiency of glycol methacrylate-embedding medium to detect morphological alterations of human saphenous vein submitted to brief and crescent pressurizations. METHODS: Saphenous veins of 20 CABG patients were randomly distributed into four experimental groups (control, 100, 200 and 300 mmHg pressures during 15 seconds). To quantify the percentage of endothelium spread over vein surface a microscope magnification of 100x was used for measurements. Morphometric analysis was performed using videomicroscopy with the Leica Qwin software in conjunction with a Leica microscope, videocamera, and an on-line computer. RESULTS: A slight tendency of quantitative increase was observed in all parameters including percentage of endothelium spread over vein surface and thickness of saphenous vein walls (intima and media layers). CONCLUSIONS: The glycol methacrylate-embedding allowed sections with adequate resolution of structural details and revealed to be an extremely useful method to study pressurized human saphenous veins.<br>OBJETIVO: Avaliar a inclusão em glicol metacrilato para estudar alterações morfológicas de veias safenas humanas submetidas a pressurizações breves e crescentes. MÉTODOS: Veias safena de 20 pacientes submetidos a cirurgia de revascularização do miocárdio foram distribuídas ao acaso em quatro grupos experimentais (controle, pressões de 100, 200 e 300 mmHg durante 15 segundos). Para quantificar a percentagem da superfície venosa recoberta por endotélio utilizou-se o aumento de 100x. A análise morfométrica foi realizada utilizando-se videomicroscopia com auxílio do software Leica Qwin em conjunto com um microscópio Leica e videocâmera, acoplados a um computador. RESULTADOS: Observou-se uma leve tendência de aumento quantitativo de todos os parâmetros avaliados, incluindo a percentagem de superfície recoberta por endotélio e a espessura das paredes das veias safenas. CONCLUSÕES: A inclusão em glicol metracrilato permitiu secções com adequada resolução dos detalhes estruturais, revelando-se um método extremamente útil para o estudo de veias safenas humanas pressurizadas

Diabetes and Vascular Disease: Basic Concepts of Nitric Oxide Physiology, Endothelial Dysfunction, Oxidative Stress and Therapeutic Possibilities

The vascular manifestations associated with diabetes mellitus (DM) result from the dysfunction of several vascular physiology components mainly involving the endothelium, vascular smooth muscle and platelets. It is also known that hyperglycemia-induced oxidative stress plays a role in the development of this dysfunction. This review considers the basic physiology of the endothelium, especially related to the synthesis and function of nitric oxide. We also discuss the pathophysiology of vascular disease associated with DM. This includes the role of hyperglycemia in the induction of oxidative stress and the role of advanced glycation end-products. We also consider therapeutic strategies.CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)FAEPA (Fundacao de Apoio ao Ensino, Pesquisa e Assistencia do Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto da Universidade de Sao Paulo), Brazi