Fish can detect and respond to a wide variety of cations in their environment, including copper. Most often fish will avoid copper during behavioural trials; however, fish may also show no response or an attraction response, depending on the concentration(s) used. While it may seem intuitive that the response to copper requires olfaction, there is little direct evidence to support this, and what evidence there is remains incomplete. In order to test if olfaction is required for avoidance of copper by fathead minnows (Pimephales promelas) copper-induced movement was compared between fish with an intact olfactory system and fish with induced anosmia. Fish in a control group or a mock-anosmic group avoided copper (approximately 10 µg/L or 62.7 nM copper sulphate) while anosmic fish did not. The evidence demonstrates that an intact olfactory system is required for copper sensing in fish.

Background and Aim: Nasogastric tube (NGT) use has been common in the immediate postoperative period in surgical patients for decades. Potential advantages include the decompression of gastric contents and the early administration of time‐sensitive medications. However, its routine use after cardiac surgery has not been established as a gold standard yet. The NGT use for prevention of postoperative nausea and vomiting has been a matter of debate in literature. Also, NGT use has also been associated with the incidence of some respiratory and gastrointestinal complications and it may be a source of significant pain and discomfort to patients. In this article, we review the current available literature regarding the use of NGT during and immediately after cardiac surgery, with particular emphasis on its potential role in enhanced postoperative recovery. Methods: We performed a database search in October 2021 using Embase, Cochrane Library, and Medline to identify studies that examined the use of NGT in patients that underwent cardiac surgery. Data and literature about NGT's impact on post‐operative nausea and vomiting, early administration of medications, interference with imaging, post‐operative complications, respiratory complications, gastrointestinal complications, pain and discomfort, and enhanced recovery after surgery were examined. Results: Three reports investigating the use of NGT to reduce post‐operative nausea and vomiting were examined with sample sizes of 114, 104, and 202. The use of NGT did not significantly reduce the incidence of post‐operative nausea and vomiting in 2/3 of the studies: a 2% nausea reduction with NGT (p < 0.05), a 7.7% nausea reduction with NGT (p = 0.6), and a 14% vomiting reduction with NGT (p = 0.007). The prevalence of pneumonia following NGT use has been shown to vary ranging from 4 to 95% with associated mortality rates of 17 to 62%. Conclusion: Based on our findings, there is currently not sufficient evidence to support the routine use of NGT during cardiac surgery. Further research is needed to establish the role of NGT in this patient population.

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