British journal of anaesthesia
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Comparative Study
Distinct long-term neurocognitive outcomes after equipotent sevoflurane or isoflurane anaesthesia in immature rats.
Many anaesthetics when given to young animals cause cell death and learning deficits that persist until much later in life. Recent attempts to compare the relative safety or toxicity between different agents have not adequately controlled for the relative dose of anaesthetic given, thereby making direct comparisons difficult. ⋯ Both isoflurane and sevoflurane delivered at 1 MAC for 4 h to immature rats caused a deficit in long-term memory. Isoflurane also caused a deficit in short-term memory. Isoflurane might be more detrimental than sevoflurane in very young animals.
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Animal studies have shown that memory deficits in the early post-anaesthetic period can be prevented by pre-treatment with an inverse agonist that preferentially inhibits α5 subunit-containing γ-aminobutyric acid type A (α5GABA(A)) receptors. The goal of this in vitro study was to determine whether inverse agonists that inhibit α5GABA(A) receptors reduce anaesthetic potentiation of GABAA receptor activity. ⋯ L-655,708 and MRK-016 reduced the potentiation by inhaled anaesthetics of GABAA receptor activated by a low concentration of GABA. Future studies are required to determine whether this effect contributes to the memory preserving properties of inverse agonists after anaesthesia.
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Elective surgery is usually preceded by preoperative diagnostics to minimize risk. The results are assumed to elicit preventive measures or even cancellation of surgery. Moreover, physicians perform preoperative tests as a baseline to detect subsequent changes. ⋯ There is no evidence derived from high-quality studies that supports routine preoperative testing in healthy adults undergoing non-cardiac surgery. Testing according to pathological findings in a patient's medical history or physical examination seems justified, although the evidence is scarce. High-quality studies, especially large randomized controlled trials, are needed to explore the effectiveness of indicated preoperative testing.
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The developmental transition from depolarizing to hyperpolarizing γ-aminobutyric acid-mediated neurotransmission is primarily mediated by an increase in the amount of the potassium-chloride cotransporter KCC2 during early postnatal life. However, it is not known whether early neuronal activity plays a modulatory role in the expression of total KCC2 mRNA and protein in the immature brain. As general anaesthetics are powerful modulators of neuronal activity, the purpose of this study was to explore how these drugs affect KCC2 expression during the brain growth spurt. ⋯ I.V. general anaesthetics do not seem to influence developmental expression of KCC2 during the brain growth spurt.