Personal protective equipment (PPE) is critical to protect healthcare workers (HCWs) from highly infectious diseases such as COVID-19. However, hospitals have been at risk of running out of the safe and effective PPE including personal protective clothing needed to treat patients with COVID-19, due to unprecedented global demand. In addition, there are only limited manufacturing facilities of such clothing available worldwide, due to a lack of available knowledge about relevant technologies, ineffective supply chains, and stringent regulatory requirements. Therefore, there remains a clear unmet need for coordinating the actions and efforts from scientists, engineers, manufacturers, suppliers, and regulatory bodies to develop and produce safe and effective protective clothing using the technologies that are locally available around the world. In this review, we discuss currently used PPE, their quality, and the associated regulatory standards. We survey the current state-of-the-art antimicrobial functional finishes on fabrics to protect the wearer against viruses and bacteria and provide an overview of protective medical fabric manufacturing techniques, their supply chains, and the environmental impacts of current single-use synthetic fiber-based protective clothing. Finally, we discuss future research directions, which include increasing efficiency, safety, and availability of personal protective clothing worldwide without conferring environmental problems.

This small, open label naturalistic study shows that up to six low dose ketamine infusions can safely be given within an existing NHS clinical structure to patients who continue their antidepressants. The response rate was comparable to that found in RCTs of single doses of ketamine in antidepressant-free patients but took slightly longer to develop.

Microsurgery of the retina would be dramatically improved by instruments that offer supra-human precision. Here, we report the results of a first-in-human study of remotely controlled robot-assisted retinal surgery performed through a telemanipulation device. Specifically, 12 patients requiring dissection of the epiretinal or inner limiting membrane over the macula were randomly assigned to either undergo robot-assisted-surgery or manual surgery, under general anaesthesia. We evaluated surgical success, duration of surgery and amount of retinal microtrauma as a proxy for safety. Surgical outcomes were equally successful in the robotic-surgery and manual-surgery groups. Differences in the amount of retinal microtrauma between the two groups were statistically insignificant, yet dissection took longer with robotic surgery (median time, 4 min 5 s) than with manual surgery (1 min 20 s). We also show the feasibility of using the robot to inject recombinant tissue plasminogen activator under the retina to displace sight-threatening haemorrhage in three patients under local anaesthesia. A safe and viable robotic system for intraocular surgery would enable precise and minimally traumatic delivery of gene therapy or cell therapy to the retina.

We have developed a model to describe the rate of oxyhaemoglobin desaturation during apnoea. This model takes into account the non-steady-state kinetics which pertain to this situation. We first derived a mathematical expression for instantaneous oxygen flux rate from the alveolar compartment. We then derived an expression to describe the effect of shunt on this flux. The effect of circulation time on real-time arterial mixed venous oxygen content difference and oxygen flux in the lung was determined graphically. We finally described a manoeuvre to accommodate the effect of the Bohr shift which is related to the increase in FACO2 during apnoea. We present plots of arterial oxyhaemoglobin saturation (SaO2) vs duration of apnoea to illustrate the individual effects of the initial fractional concentration of oxygen in the alveolus (FAO2initial), alveolar volume (VA), shunt fraction (QS/QT), oxygen consumption rate (VO2), total blood volume (QT) and haemoglobin concentration (Hb). The model is illustrated by examples of paediatric, morbidly obese and post-operative scenarios. The postoperative scenario is particularly notable for the effect of a combination of small changes in individual variables leading to a large overall effect on the rate of oxyhaemoglobin desaturation.

Concepts of continuous ventilation and perfusion havefounded mathematical models of lung gas mixing and cardiopulmonary blood±gas exchange, whether for anaesthetic vapour uptake or for cardiorespiratory measurement, for several decades now. 20 28 37 42 The beauty of continuousventilation and perfusion models is that they allow mathematical expressions that are readily soluble, and they describe body processes in a linear and intuitive way. Hlastala and Robertson 21 describe the success of these conventional approaches,`For the lung, perhaps more than any other organ, simple models have proven exceptionally fruitful in the process of investigation. Our textbooks are ®lled with analogies of springs and dashpots, sluices and waterfalls, gravitational gradients, and bubbles. When the simplest analogies failed to precisely represent observed properties, the inclusion of two or three compartments with different parameters usually suf®ced to smooth over discrepancies between predictions and observations.'These simple mathematical models are attractive yet beguiling. They can mislead because they divert our gaze from the reality that ventilation is not continuous but tidal in nature. Unfortunately, mathematical models that involve discontinuities in inspired and expired gas¯ow, and therefore in lung volume, produce equations that do not have simple analytical solutions. There is a reluctance to consider, let alone teach from, such`tidal' models in clinical practice because they appear complex and are intuitively opaque.Here we can see the application of the philosophical concept of Occam's razor. Named after the 14th century logician and Franciscan friar, William of Occam, the principle states:`Frustra ®t per plura quod potest ®eri per pauciora', which very roughly paraphrased means`when you have two competing theories which make exactly the same predictions, the one that is simpler is the better'. This philosophy is a form of logical positivism in which any