Veterinary anaesthesia and analgesia
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Review
Intraoperative nociception-antinociception monitors: A review from the veterinary perspective.
To review monitors currently available for the assessment of nociception-antinociception in veterinary medicine. ⋯ The provision of adequate antinociception is difficult to achieve in veterinary anaesthesia. Currently, heart rate and arterial blood pressure are used to monitor the response to a noxious stimulus during anaesthesia, with minimum alveolar concentration-sparing effect and stress-related hormones used for this purpose in research studies. However, since none of these variables truly assess intraoperative nociception, several alternative monitoring devices have been developed for use in humans. These nociceptive-antinociceptive monitoring systems derive information from variables, such as electroencephalography, parasympathetic nervous system (PNS) response, sympathetic nervous system response and electromyography. Several of these monitoring systems have been investigated in veterinary medicine, although few have been used to assess intraoperative nociception in animals. There is controversy regarding their effectiveness and clinical use in animals. A nociceptive-antinociceptive monitoring system based on the PNS response has been developed for use in cats, dogs and horses. It uses the parasympathetic tone activity index, which is believed to detect inadequate intraoperative nociception-antinociception balance in veterinary anaesthesia. Nonetheless, there are limited published studies to date, and cardiovascular variables remain the gold standard. Consequently, further studies in this area are warranted.
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Attention is drawn to the potential of global warming to influence the health and wellbeing of the human race. There is increasing public and governmental pressure on healthcare organisations to mitigate and adapt to the climate changes that are occurring. The science of anaesthetic agents such as nitrous oxide and the halogenated anaesthetic agents such as greenhouse gases and ozone-depleting agents is discussed and quantified. Additional environmental impacts of healthcare systems are explored. The role of noninhalational anaesthetic pharmaceuticals is discussed, including the environmental life-cycle analyses of their manufacture, transport, disposal and use. The significant role of anaesthetists in recycling and waste management, resource use (particularly plastics, water and energy) and engagement in sustainability are discussed. Finally, future directions for sustainability in veterinary anaesthesia are proposed. ⋯ Veterinary anaesthetists have a considerable opportunity to drive sustainability within their organisations through modification of their practice, research and education. The principles of sustainability may help veterinary anaesthetists to mitigate and adapt to our environmental crisis. Due to their particular impact as greenhouse gases, anaesthetic agents should be used conservatively with the lowest safe fresh gas flow possible. Technologies for reprocessing anaesthetic agents are described.
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Orbital and globe surgeries are commonly performed in companion animals and are considered to cause moderate to severe pain. Regional anesthesia techniques can provide complete sensory blockade, analgesia for painful procedures and improve surgical conditions. The purpose of this review is to summarize local and regional anesthesia techniques for ophthalmic surgery in dogs and cats with emphasis on veterinary publications in the past 12 years. ⋯ Reported techniques include regional techniques such as retrobulbar anesthesia, peribulbar anesthesia and sub-Tenon's anesthesia, and local techniques such as eyelid and conjunctival infiltration, intracameral anesthesia, splash block and insertion of intraorbital absorbable gelatin sponge infused with local anesthetic. Administration guidelines, indications and contraindications, and complications of each technique are discussed. Regional anesthesia techniques were reported to be effective during ophthalmic surgeries and are recommended for use as part of the anesthetic regimen and pain management in animals. However, the veterinary literature is still lacking controlled clinical trials and adverse events reports; therefore, there is very little evidence for choosing one technique over another.
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Review
Review of hypoxaemia in anaesthetized horses: predisposing factors, consequences and management.
To discuss how hypoxaemia might be harmful and why horses are particularly predisposed to developing it, to review the strategies that are used to manage hypoxaemia in anaesthetized horses, and to describe how successful these strategies are and the adverse effects associated with them. ⋯ Although there is no evidence that hypoxaemia is associated with increased morbidity and mortality in anaesthetized horses, most anaesthetists would agree that it is important to recognise and prevent or treat it. Favourable anatomical and physiological adaptations of a horse for exercise adversely affect gas exchange once the animal is recumbent. Hypoxaemia is recognised more frequently in horses than in other domestic species during general anaesthesia, although its incidence in healthy horses remains unreported. Management of hypoxaemia in anaesthetized horses is challenging and often unsuccessful. Positive pressure ventilation strategies to address alveolar atelectasis in humans have been modified for implementation in recumbent anaesthetized horses, but are often accompanied by unpredictable and unacceptable cardiopulmonary adverse effects, and some strategies are difficult or impossible to achieve in adult horses. Furthermore, anticipated beneficial effects of these techniques are inconsistent. Increasing the inspired fraction of oxygen during anaesthesia is often unsuccessful since much of the impairment in gas exchange is a direct result of shunt. Alternative approaches to the problem involve manipulation of pulmonary blood away from atelectatic regions of the lung to better ventilated areas. However, further work is essential, with particular focus on survival associated with general anaesthesia in horses, before any technique can be accepted into widespread clinical use.
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In UK law, allowing an animal protected under the Animal Welfare Act 2006 (AWA 2006) (as devolved) to suffer 'unnecessarily' may render the person responsible for it to prosecution. The act does not define suffering, although 'case law' suggests that suffering encompasses more than pain. Clinicians responsible for animals under their care in the intensive care unit (ICU) are likely to also be responsible in law for the welfare of those animals, and may be called upon to justify why any suffering was necessary, or more likely, why they did not act to end any suffering when it became 'unnecessary'. As animals are considered to be 'property' in law, the legal requirement to prevent 'unnecessary suffering' may conflict with the owner's property rights. Additionally, professional conflict may arise between the clinicians whose opinion of where the border between 'heroic treatment' and 'futile treatment' lays. Different types of suffering that might be relevant to clinical and ethical decision making for patients in the ICU are discussed, with suggestions for how these might be categorised, measured and recorded, so that objective data is available on which discussions about the animal's actual and projected welfare can be held with the animal's owner, and other clinicians involved in the case. ⋯ The development of 'welfare scoring systems' for the ICU may assist clarifying the point at which heroic treatment is becoming futile, and therefore suffering becoming unnecessary, and place veterinary anaesthetists in an even stronger position to act as 'advocate for the animal' in their care.