Inhalative sedation with small tidal volumes under venovenous ECMO
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Inhalative sedation is an emerging method for long-term sedation in intensive care therapy. There is evidence that it is easy to control and may be beneficial compared to intravenous sedation. Yet little is known about the use in patients with compromised lung function. In this retrospective analysis, we searched files of patients receiving inhalative sedation under venovenous extracorporeal membrane oxygenator (vv-ECMO) support due to lung failure.
After ethical approval, we performed a retrospective analysis of patients receiving vv-ECMO support and inhalative sedation in the surgical ICU in 2015. Isoflurane was administered via the AnaConDa®-system. Sedation was tested using Richmond Agitation and Sedation scale (RASS).
7 patients were identified. Median age was 50 years (26/70 years). All were male. Median ECMO runtime was 129 h (37/1008 h) and the survival rate was 57.9%. Dose of isoflurane was 1.7 ml/h (0.8 / 4.0 ml/h) resulting in expiratory concentrations of 0.8 Vol% (0.3/1.8 Vol%), inspiratory of 0.6 Vol% (0.1/1.4 Vol%). Higher concentrations of isoflurane were associated with increased depth of sedation (expiratory p = 0.016; inspiratory p = 0.027; averaged p = 0.015). With tidal volume below 350 ml, association was still present for expiratory and averaged concentrations of isoflurane (expiratory p = 0.031; inspiratory p = 0.082; average p = 0.039).
This is the first study that shows that inhalative concentrations of isoflurane are associated with depth of sedation in patients with lung failure. We were able to show that even with major impacts in lung mechanics and function targeted sedation with volatile anaesthetics is feasible and dose–response relationship appears to exist.
KeywordsECMO Lung failure Inhalative sedation Isoflurane Anaconda ARDS Adult Intensive care Sedation
Venovenous extracorporeal membrane oxygenator
Richmond agitation and sedation scale
Acute respiratory distress syndrome
Biphasic positive airway pressure
Continuous positive airway pressure and pressure support
Dose of isoflurane per syringe pump in
Expiratory concentration of isoflurane
Inspiratory concentration of isoflurane
Average of the in- and expiratory concentration of isoflurane
AR had full access to the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. UH and CW assisted in collection of the data. UH, CW, PZ assisted in analysis and interpretation of the results. AR, PZ, TS, CW, UH contributed substantially to the study design, interpretation of the data and writing and critical revision of the manuscript. All authors read and approved the final manuscript.
Compliance with ethical standards
Ethics committee of the Ruhr-University Bochum (Ethical committee number 17-6050 BR).
Consent for publication
Conflict of interest
The authors declare that they have no conflict of interest.