We have read with interest the article by Añón et al.1 on the use of anesthetic gases in sedating critically ill patients. This article presents facts and points out uncertainties regarding the usefulness of anesthetic gases. In this regard, we would like to make some additional comments.

Just as there are significant differences between intravenous sedation drugs, a precise distinction must also be made between isoflurane and sevoflurane in the case of inhaled sedation. Currently, only isoflurane is approved for this indication, but it is important to highlight the differences between the two drugs.

Isoflurane has a significant bronchodilator effect at high doses (>1 MAC), which is higher than the recommended dose for sedation. Such doses could compromise the hemodynamics in severe status asthmaticus, where auto-PEEP and hypercapnia pose challenges. In this scenario, despite recent recommendations,2 sevoflurane might be preferable given its greater bronchodilator effect at lower MAC, although it should be used on an off-label basis for a short period of time in order to minimize its potential nephrotoxicity. These observations underscore the need for comparative studies to guide its use in refractory status asthmaticus.

We agree with the authors that isoflurane has a greater anticonvulsant effect than sevoflurane, which justifies its inclusion in the treatment of highly refractory status epilepticus. Use of the drug requires close monitoring due to the possible hemodynamic repercussions and the risk of worsening intracranial hypertension. However, the images in the aforementioned article do not firmly demonstrate its usefulness. Figure 1 shows no status-related data, and there is no clear justification for increasing the isoflurane dose to achieve seizure suppression.

Another interesting aspect not addressed by Añón et al., is the environmental contamination resulting from the use of inhaled anesthetics. Anesthesiology and intensive care medicine are actively addressing the environmental impact of their practices.3 In the anesthetic setting, a relevant measure is reducing the use of inhaled agents in favor of total intravenous anesthesia (TIVA) to mitigate their contribution to global warming. There are solid studies that support the benefits of this change.4 It should be noted that the global warming potential of isoflurane is approximately four times greater than that of sevoflurane.

Furthermore, the impact of inhaled anesthetics versus intravenous sedatives on cognitive function and delirium in critically ill patients requires further analysis. Rather than using a “one sedative for all” strategy, a personalized approach to sedation is essential. Intensivists must carefully consider the pros and cons of each drug, rather than making decisions based solely on tendencies. For deep sedation, propofol is the preferred choice. Midazolam, ketamine, isoflurane and sevoflurane should be reserved for situations in which they offer clear advantages over propofol and are used only under close monitoring. This approach is in line with the «Dutch Approach» to anesthesia5: TIVA when possible and inhalation anesthesia when necessary.