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Summary: The amount of aerosol generation associated with the use of positive pressure ventilation via a supraglottic airway device has not been quantified. We conducted a two‐group, two‐centre, prospective cohort study in which we recruited 21 low‐risk adult patients scheduled for elective surgery under general anaesthesia with second‐generation supraglottic airway devices. An optical particle sizer and an isokinetic sampling probe were used to record particle concentrations per second at different size distributions (0.3–10 μm) during use as well as baseline levels during two common activities (conversation and coughing). There was a median (IQR [range]) peak increase of 2.8 (1.5–4.5 [1–28.1]) and 4.1 (2.0–7.1 [1–18.2]) times background concentrations during SAD insertion and removal. Most of the particles generated during supraglottic airway insertion (85.0%) and removal (85.3%) were < 3 μm diameter. Median (IQR [range]) aerosol concentration generated by insertion (1.1 (0.6–5.1 [0.2–22.3]) particles.cm−3) and removal (2.1 (0.5–3.0 [0.1–18.9]) particles.cm−3) of SADs were significantly lower than those produced during continuous talking (44.5 (28.3–70.5 [2.0–134.5]) particles.cm−3) and coughing (141.0 (98.3–202.8 [4.0–296.5]) particles.cm−3) (p < 0.001). The aerosol levels produced were similar with the two devices. The proportion of easily inhaled and small particles (<1 μm) produced during insertion (57.5%) and removal (57.5%) was much lower than during talking (99.1%) and coughing (99.6%). These results suggest that the use of supraglottic airway devices in low‐risk patients, even with positive pressure ventilation, generates fewer aerosols than speaking and coughing in awake patients. [ABSTRACT FROM AUTHOR]

Summary: Propfol‐remifentanil‐based total intravenous anaesthesia has dominated recent clinical practice due to its favourable pharmacokinetic profile. Interruption in remifentanil supply has presented an opportunity to diversify or even avoid the use of opioids and consider adjuncts to propofol‐based total intravenous anaesthesia. Propofol, while a potent hypnotic, is not an effective analgesic. The administration of opioids, along with other adjuncts such as α‐2 adrenoceptor agonists, magnesium, lidocaine, ketamine and nitrous oxide provide surgical anaesthesia and avoids large doses of propofol being required. We provide an overview of both target‐control and manual infusion regimes for the alternative opioids: alfentanil, sufentanil and fentanyl. The optimal combination of hypnotic‐opioid dose, titration sequence and anticipated additional postoperative analgesia required depend on the chosen combination. In addition, we include a brief discussion on the role of non‐opioid adjuncts in total intravenous anaesthesia, suggested doses and expected reduction in propofol dose. [ABSTRACT FROM AUTHOR]

This article discusses the use of electronic cigarettes (e-cigarettes) as a smoking cessation intervention in the peri-operative period. The authors highlight that while e-cigarettes have been found to be effective in increasing abstinence from tobacco smoking in the general population, their impact in the peri-operative population is still uncertain. The article raises concerns about the potential respiratory, cardiovascular, and wound complications associated with e-cigarette use, as well as the potential interaction between e-liquids and anaesthetic drugs. The authors acknowledge the benefits of smoking cessation but challenge the idea that e-cigarettes are a transformative intervention in the peri-operative period. [Extracted from the article]

Summary: Various techniques have been explored to prolong the duration and improve the efficacy of local anaesthetic nerve blocks. Some of these involve mixing local anaesthetics or adding adjuncts. We did a literature review of studies published between 01 May 2011 and 01 May 2021 that studied specific combinations of local anaesthetics and adjuncts. The rationale behind mixing long‐ and short‐acting local anaesthetics to hasten onset and extend duration is flawed on pharmacokinetic principles. Most local anaesthetic adjuncts are not licensed for use in this manner and the consequences of untested admixtures and adjuncts range from making the solution ineffective to potential harm. Pharmaceutical compatibility needs to be established before administration. The compatibility of drugs from the same class cannot be inferred and each admixture requires individual review. Precipitation on mixing (steroids, non‐steroidal anti‐inflammatory drugs) and subsequent embolisation can lead to serious adverse events, although these are rare. The additive itself or its preservative can have neurotoxic (adrenaline, midazolam) and/or chondrotoxic properties (non‐steroidal anti‐inflammatory drugs). The prolongation of block may occur at the expense of motor block quality (ketamine) or block onset (magnesium). Adverse effects for some adjuncts appear to be dose‐dependent and recommendations concerning optimal dosing are lacking. An important confounding factor is whether studies used systemic administration of the adjunct as a control to accurately identify an additional benefit of perineural administration. The challenge of how best to prolong block duration while minimising adverse events remains a topic of interest with further research required. [ABSTRACT FROM AUTHOR]

With different pharmacokinetics in a drug mixture, a decision must be made to guide the infusion by one of the drugs with the potential risk of over- or under-dosing the other. The Medicines and Healthcare products Regulatory Agency in the UK and the US Food and Drug Administration have not approved the use of other medications including ketamine, remifentanil and dexmedetomidine but these practices have gained popularity. In some circumstances, there may be persuasive reasons for mixing two or more parenteral drug solutions, such as difficult intravenous access or in palliative care syringe drivers, but most of these situations are not applicable to routine intra-operative drug administration. Keywords: pharmacokinetics: pharmacodynamics; pharmacology; safety EN pharmacokinetics: pharmacodynamics pharmacology safety 260 263 4 02/07/22 20220301 NES 220301 The development and refinement of anaesthetic drugs and their administration have markedly increased safety and titratability while decreasing morbidity. [Extracted from the article]

Are tracheal intubation and extubation aerosol-generating procedures? Keywords: airborne; contact; coronavirus; COVID-19; droplet; personal protective equipment; intubation; extubation EN airborne contact coronavirus COVID-19 droplet personal protective equipment intubation extubation 151 155 5 01/15/21 20210201 NES 210201 "a wise man proportions his belief to the evidence" David Hume (Scottish Enlightenment Philosopher, 1711-1776) The COVID-19 pandemic has significantly impacted peri-operative care due to staff redeployment and a reduction in elective surgery secondary to depletion of resources and a requirement for increased infection control procedures in order to protect healthcare staff. As well as patients with severe COVID-19 infection who require tracheal intubation, patients may be relatively asymptomatic and present for surgery. If sicker patients pose a higher transmission risk, is a healthcare worker performing tracheal intubation contracting COVID-19 highly likely?. [Extracted from the article]

Lipopolysaccharide (LPS) from Gram-negative bacteria induces an immune response and impairs reproduction through suppression of gonadotropin releasing hormone (GnRH), subsequently luteinizing hormone (LH) secretion. While there is evidence that acute inflammation inhibits kisspeptin, little is known about the impact of chronic inflammation on this key reproductive neuropeptide in livestock species. Thus, we sought to examine a central mechanism whereby LPS suppresses LH secretion in sheep. Twenty wethers were randomly assigned to one of five treatment groups: control (CON; n=4), single acute IV LPS dose (SAD; n=4), daily acute IV LPS dose (DAD; n=4), daily increasing IV LPS dose (DID; n=4), and chronic subcutaneous LPS dose (CSD; n=4). On Days 1 and 7, blood samples were collected every 12 minutes for 360 minutes using jugular venipuncture. Following blood collection on Day 7, all animals were euthanized, brain tissue was perfused with 4% paraformaldehyde, and hypothalamic blocks were removed and processed for immunohistochemistry. On Day 1, LH pulse frequency was significantly lower (p=0.02) in SAD (0.25 ± 0.1 pulses/hour), DAD (0.25 ± 0.1 pulses/hour), DID (0.35 ± 0.1 pulses/hour), and CSD (0.40 ± 0.1 pulses/hour) compared to CON (0.70 ±0.1 pulses/hour). On Day 7, only DID animals (0.35 ± 0.1 pulses/hour) had significantly lower (p=0.049) LH pulse frequency compared to controls (0.85 ± 0.1 pulse/hour). Furthermore, only DID animals (33.3 ± 10.9 cells/section/animal) had significantly fewer (p=0.001) kisspeptin-immunopositive cells compared to controls (82.6 ± 13.6 cells/section/animal). Taken together, we suggest that daily increasing doses of LPS is a powerful inhibitor of kisspeptin neurons in young male sheep and a physiologically relevant model to examine the impact of chronic inflammation on the reproductive axis in livestock., Competing Interests: Declaration of competing interest The authors report no conflicts of interest to disclose., (Copyright © 2024. Published by Elsevier Inc.)

Gonadotropin-releasing hormone (GnRH) neurons are the final common conduit from the central nervous system in the reproductive axis, controlling luteinizing hormone (LH) secretion from the gonadotropes of the anterior pituitary. Although it is generally accepted that undernutrition inhibits GnRH/LH secretion, the central mechanisms that underlie the link between energy balance and reproduction remain to be fully elucidated. Sheep have been a longstanding and invaluable animal model for examination of the nutritional regulation of GnRH/LH secretion, given their ability to serve a biomedical and agricultural purpose. In this review, we summarize work that has used the ovine model to examine the central mechanisms whereby undernutrition regulates GnRH/LH secretion. Specifically, we focus our attention to the arcuate nucleus of the hypothalamus and on neurons that express kisspeptin, neurokinin B, dynorphin, proopiomelanocortin, and neuropeptide y/agouti-related peptide (NPY/AgRP). We examine their roles in mediating the effects of leptin and insulin and their effects on LH during undernutrition, as well as their regulation under conditions of undernutrition. This review will also highlight the interactions between the aforementioned neuronal networks themselves, which may be important for our understanding of the roles each play in relaying information regarding energy status during times of undernutrition to ultimately regulate GnRH/LH secretion., (Copyright © 2020. Published by Elsevier Inc.)