Peri-operative SARS-CoV-2 infection increases postoperative mortality. The aim of this study was to determine the optimal duration of planned delay before surgery in patients who have had SARS-CoV-2 infection. This international, multicentre, prospective cohort study included patients undergoing elective or emergency surgery during October 2020. Surgical patients with pre-operative SARS-CoV-2 infection were compared with those without previous SARS-CoV-2 infection. The primary outcome measure was 30-day postoperative mortality. Logistic regression models were used to calculate adjusted 30-day mortality rates stratified by time from diagnosis of SARS-CoV-2 infection to surgery. Among 140,231 patients (116 countries), 3127 patients (2.2%) had a pre-operative SARS-CoV-2 diagnosis. Adjusted 30-day mortality in patients without SARS-CoV-2 infection was 1.5% (95%CI 1.4-1.5). In patients with a pre-operative SARS-CoV-2 diagnosis, mortality was increased in patients having surgery within 0-2 weeks, 3-4 weeks and 5-6 weeks of the diagnosis (odds ratio (95%CI) 4.1 (3.3-4.8), 3.9 (2.6-5.1) and 3.6 (2.0-5.2), respectively). Surgery performed ≥ 7 weeks after SARS-CoV-2 diagnosis was associated with a similar mortality risk to baseline (odds ratio (95%CI) 1.5 (0.9-2.1)). After a ≥ 7 week delay in undertaking surgery following SARS-CoV-2 infection, patients with ongoing symptoms had a higher mortality than patients whose symptoms had resolved or who had been asymptomatic (6.0% (95%CI 3.2-8.7) vs. 2.4% (95%CI 1.4-3.4) vs. 1.3% (95%CI 0.6-2.0), respectively). Where possible, surgery should be delayed for at least 7 weeks following SARS-CoV-2 infection. Patients with ongoing symptoms ≥ 7 weeks from diagnosis may benefit from further delay.

SARS-CoV-2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri-operative or prior SARS-CoV-2 were at further increased risk of venous thromboembolism. We conducted a planned sub-study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 days of surgery. SARS-CoV-2 diagnosis was defined as peri-operative (7 days before to 30 days after surgery); recent (1-6 weeks before surgery); previous (≥7 weeks before surgery); or none. Information on prophylaxis regimens or pre-operative anti-coagulation for baseline comorbidities was not available. Postoperative venous thromboembolism rate was 0.5% (666/123,591) in patients without SARS-CoV-2; 2.2% (50/2317) in patients with peri-operative SARS-CoV-2; 1.6% (15/953) in patients with recent SARS-CoV-2; and 1.0% (11/1148) in patients with previous SARS-CoV-2. After adjustment for confounding factors, patients with peri-operative (adjusted odds ratio 1.5 (95%CI 1.1-2.0)) and recent SARS-CoV-2 (1.9 (95%CI 1.2-3.3)) remained at higher risk of venous thromboembolism, with a borderline finding in previous SARS-CoV-2 (1.7 (95%CI 0.9-3.0)). Overall, venous thromboembolism was independently associated with 30-day mortality ). In patients with SARS-CoV-2, mortality without venous thromboembolism was 7.4% (319/4342) and with venous thromboembolism was 40.8% (31/76). Patients undergoing surgery with peri-operative or recent SARS-CoV-2 appear to be at increased risk of postoperative venous thromboembolism compared with patients with no history of SARS-CoV-2 infection. Optimal venous thromboembolism prophylaxis and treatment are unknown in this cohort of patients, and these data should be interpreted accordingly.

In a prospective study of 13 patients requiring pneumonectomy for unilateral post-tuberculous lung destruction the left side was found to be affected in 12. Review of a further 172 cases showed the left lung to have been destroyed in 109 (63%). It is suggested that this predominance of the left side is due to the anatomical characteristics of the left main bronchus and that disordered haemodynamics also appear to play a part.Unilateral total post-tuberculous lung destruction is a well recognised cause ofmorbidity and mortality.' 2 In Saudi Arabia late presentation and poor compliance with treatment for tuberculosis (as low as 30%') account for an appreciable number of patients presenting in this way, but very few studies have dealt with the problem in detail.4 We report the clinicopathological and haemodynamic findings in 13 patients coming to surgery at King Khalid University Hospital. The left lung was affected more frequently than the right, and we discuss the reasons for this predilection. Patients and methodsWe studied 13 patients with unilateral lung destruction before elective pneumonectomy, by bronchoscopy, bronchography, pulmonary angiography, thoracic aortography, ven-

One hundred sixty-one patients were found to have lower-lung-field tuberculosis in a retrospective study of 1566 cases of pulmonary tuberculosis admitted to Sahary Chest Hospital, Riyadh. This represents 10.3% of the total admissions over a period of four years. Lower-lung-field tuberculosis is more common in females. Twenty-six percent of the patients had had previous antitubercular treatment. Sputum conversion took 40.4 days. Average hospital stay was 50 days. Hemoptysis was found in 46% of cases and diabetes mellitus was discovered in 13%. Chest x-ray studies showed right lung involvement in 46% of cases, bilateral involvement in 29%, and left lung involvement in 25% of cases. A cavitary lesion was found in 49%.

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Artificial neural networks (ANNs) ability to learn, correct errors, and transform a large amount of raw data into beneficial medical decisions for treatment and care has increased in popularity for enhanced patient safety and quality of care. Therefore, this paper reviews the critical role of ANNs in providing valuable insights for patients’ healthcare decisions and efficient disease diagnosis. We study different types of ANNs in the existing literature that advance ANNs’ adaptation for complex applications. Specifically, we investigate ANNs’ advances for predicting viral, cancer, skin, and COVID-19 diseases. Furthermore, we propose a deep convolutional neural network (CNN) model called ConXNet, based on chest radiography images, to improve the detection accuracy of COVID-19 disease. ConXNet is trained and tested using a chest radiography image dataset obtained from Kaggle, achieving more than 97% accuracy and 98% precision, which is better than other existing state-of-the-art models, such as DeTraC, U-Net, COVID MTNet, and COVID-Net, having 93.1%, 94.10%, 84.76%, and 90% accuracy and 94%, 95%, 85%, and 92% precision, respectively. The results show that the ConXNet model performed significantly well for a relatively large dataset compared with the aforementioned models. Moreover, the ConXNet model reduces the time complexity by using dropout layers and batch normalization techniques. Finally, we highlight future research directions and challenges, such as the complexity of the algorithms, insufficient available data, privacy and security, and integration of biosensing with ANNs. These research directions require considerable attention for improving the scope of ANNs for medical diagnostic and treatment applications.

In a retrospective review of 241 patients with active pulmonary tuberculosis, hypercalcemia was found in 62 (26%). It was detected on presentation in 48 patients and developed in 14 patients 4 to 6 weeks after the start of antituberculous chemotherapy. The mean (± SD) serum calcium level in those cases was 2.78 (± 0.137) mmol/L. The majority of cases (67.6%) had a mild rise in the calcium level that remained below 2.8 mmol/L but 35% had a level that ranged between 2.8 and 3.0 mmol/L. Only 2.4% had serum level higher than 3.0 mmol/L, which could explain the predominant absence of hypercalcemia-related symptoms. Hypercalcemia was more common in patients older than 50 years (P < 0.05), but this did not correlate with the extent of the tuberculosis shown on radiological evaluation. Spontaneous return to normocalcemia occurred in all 42 patients who underwent serial assessments of their serum calcium concentration, 6 to 8 weeks after the start of chemotherapy. Saudi Arabia is known to have a high prevalence of vitamin D deficiency, but none of our patients were immobilized or had received vitamin D supplements or multivitamins. This supports the view that vitamin D intake does not play a major role in inducing hypercalcemia in cases of active pulmonary tuberculosis, as has been suspected.