Establishing a COVID-secure site for elective surgery during the COVID pandemic: An observational study.

INTRODUCTION: Maintaining timely and safe delivery of major elective surgery during the COVID-19 pandemic is essential to manage cancer and time-critical surgical conditions. Our NHS Trust established a COVID-secure elective site with a level 2 Post Anaesthetic Care Unit (PACU) facility. Patients requiring level 3 Intensive Care Unit admission were transferred to a non-COVID-secure site. We investigated the relationship between perioperative anaesthetic care and outcomes. MATERIALS AND METHODS: All consecutive patients undergoing major surgery at the COVID-secure site between June and November 2020 were included. Patient demographics, operative interventions and 30-day outcomes were recorded. Multivariate logistic regression was used to determine the odds ratio of outcomes according to PACU length of stay and the use of spinal or epidural anaesthesia, with age, sex, malignancy status and American Society of Anesthesiologists grade as independent co-variables. RESULTS: There were 280 patients. PACU length of stay >23h was associated with increased 30-day complications. Epidural anaesthesia was associated with PACU length of stay >23h, increased total length of stay, increase hospital transfer and 30-day complications. Two patients acquired nosocomial COVID-19 following hospital transfer. DISCUSSION: Establishing a separate COVID-secure site has facilitated delivery of major elective surgery during the COVID-19 pandemic. Choice of perioperative anaesthesia and utilisation of PACU appear likely to affect the risk of adverse outcomes.

How Do Antihypertensive Drugs Work? Insights from Studies of the Renal Regulation of Arterial Blood Pressure.

Though antihypertensive drugs have been in use for many decades, the mechanisms by which they act chronically to reduce blood pressure remain unclear. Over long periods, mean arterial blood pressure must match the perfusion pressure necessary for the kidney to achieve its role in eliminating the daily intake of salt and water. It follows that the kidney is the most likely target for the action of most effective antihypertensive agents used chronically in clinical practice today. Here we review the long-term renal actions of antihypertensive agents in human studies and find three different mechanisms of action for the drugs investigated. (i) Selective vasodilatation of the renal afferent arteriole (prazosin, indoramin, clonidine, moxonidine, α-methyldopa, some Ca(++)-channel blockers, angiotensin-receptor blockers, atenolol, metoprolol, bisoprolol, labetolol, hydrochlorothiazide, and furosemide). (ii) Inhibition of tubular solute reabsorption (propranolol, nadolol, oxprenolol, and indapamide). (iii) A combination of these first two mechanisms (amlodipine, nifedipine and ACE-inhibitors). These findings provide insights into the actions of antihypertensive drugs, and challenge misconceptions about the mechanisms underlying the therapeutic efficacy of many of the agents.