Environmental safety: Air pollution while using MIRUS™ for short-term sedation in the ICU

Abstract

Background: MIRUS™ is a device for target-controlled inhalational sedation in the ICU in combination with use of isoflurane, or sevoflurane, or desflurane. The feasibility of this device has recently been proven; however, ICU staff exposure may restrict its application. We investigated ICU ambient room pollution during daily work to estimate ICU personnel exposure while using MIRUS™.

Methods: This observational study assessed pollution levels around 15 adult surgical patients who received volatile anaesthetics-based sedation for a median of 11 hours. Measurements were performed by photoacoustic gas monitoring in real-time at different positions near the patient and in the personnel's breathing zone. Additionally, the impact of the Clean Air™ open reservoir scavenging system on volatile agent pollution was evaluated.

Results: Baseline concentrations [ppm] during intervention and rest periods were isoflurane ${\overline{c}}_{\mathrm{mean}}$ = 0.58 ± 0.49, ${\overline{c}}_{\max }$ = 5.72; sevoflurane ${\overline{c}}_{\mathrm{mean}}$ = 0.22 ± 0.20, ${\overline{c}}_{\max }$ = 7.93; and desflurane ${\overline{c}}_{\mathrm{mean}}$ = 0.65 ± 0.57, ${\overline{c}}_{\max }$ = 6.65. Refilling MIRUS™ with liquid anaesthetic yielded gas concentrations of ${\overline{c}}_{\mathrm{mean}}$ = 2.18 ± 1.48 ppm and ${\overline{c}}_{\max }$ = 13.03 ± 9.37 ppm in the personnel's breathing zone. Air pollution in the patient's room was approximately five times higher without a scavenging system.

Conclusion: Ambient room pollution was minimal in most cases, and the measured values were within or below the recommended exposure limits. Caution should be taken during refilling of the MIRUS™ system, as this was accompanied by higher pollution levels. The combined use of air-conditioning and gas scavenging systems is strongly recommended.

Keywords: MIRUS; desflurane; enviromental safety; exposure limits; gas pollution; inhalational sedation; intensive care unit; isoflurane; risk reduction; sevoflurane.