Use of the MIRUS™ system for general anaesthesia during surgery: a comparison of isoflurane, sevoflurane and desflurane

Abstract

The MIRUS™ system enables automated end-expired control of volatile anaesthetics. The device is positioned between the Y-piece of the breathing system and the patient's airway. The system has been tested in vitro and to provide sedation in the ICU with end-expired concentrations up to 0.5 MAC. We describe its performance in a clinical setting with concentrations up to 1.0 MAC. In 63 ASA II-III patients undergoing elective hip or knee replacement surgery, the MIRUS™ was set to keep the end-expired desflurane, sevoflurane, or isoflurane concentration at 1 MAC while ventilating the patient with the PB-840 ICU ventilator. After 1 h, the ventilation mode was switched from controlled to support mode. Time to 0.5 and 1 MAC, agent usage, and emergence times, work of breathing, and feasibility were assessed. In 60 out of 63 patients 1.0 MAC could be reached and remained constant during surgery. Gas consumption was as follows: desflurane (41.7 ± 7.9 ml h), sevoflurane (24.3 ± 4.8 ml h) and isoflurane (11.2 ± 3.3 ml h). Extubation was faster after desflurane use (min:sec): desflurane 5:27 ± 1:59; sevoflurane 6:19 ± 2:56; and isoflurane 9:31 ± 6:04. The support mode was well tolerated. The MIRUS™ system reliable delivers 1.0 MAC of the modern inhaled agents, both during mechanical ventilation and spontaneous (assisted) breathing. Agent usage is highest with desflurane (highest MAC) but results in the fastest emergence. Trial registry number: Clinical Trials Registry, ref.: NCT0234509.

Use of MIRUS™ for MAC-driven application of isoflurane, sevoflurane, and desflurane in postoperative ICU patients: a randomized controlled trial

“…Two studies investigated the VA consumption of MIRUS™ at 1.0 MAC. A benchmark study reported a DES consumption of 40 ml per hour to achieve a fraction of 6.0–6.6%, and a clinical trial revealed a threefold higher consumption for ISO and SEVO, as well as a one and a half times higher consumption for DES compared to our results during hip and knee replacement surgery (respiratory minute volume 6–7 l min −1 ) [5, 8]. These high consumptions can be explained by the fact that the reflection efficiency of the MIRUS™ is highest at expiratory VA fractions of about 0.2–1.0%, and thus, more VA gets lost at higher concentrations [5].…”

“…Sample size calculation was conducted in g power (Heinrich-Heine-University, Dusseldorf, Germany) and is based on a pilot study investigating the VA consumption of MIRUS™ at 1.0 MAC during surgery [8]. Significantly different VA consumption rates of the three gases were reported with an estimated effect size of d = 3.56, which was transferred to the current study design.…”

Extracorporeal membrane oxygenation and inhaled sedation in coronavirus disease 2019-related acute respiratory distress syndrome

“…The prerequisite for using the Anaesthetic Conserving Device (ACD) AnaConDa ® (Sedana Medical AB, Danderyd, Sweden) or the MIRUS TM system (TIM, Koblenz, Germany) depends on several clinical parameters (see Figure 1 ). If lung compliance is acceptable, and CO 2 can be reduced sufficiently, both types of systems are able to maintain spontaneous breathing[ 19 - 21 ]. However, if lung compliance is poor, reduction of dead space and active humidification is necessary, which can be facilitated by inhaled sedation via a circle breathing system[ 22 , 23 ].…”

“…the dead space. The volumetric dead space of the MIRUS TM system is 100 mL[ 19 ], whereas the volumetric dead space for the AnaConDa ® system ACD-100 is 100 mL and 50 mL for the ACD-50[ 23 ]. However, the ECMO system eliminates CO 2 effectively.…”

Sedation with inhaled agents in the ICU: what are we waiting for?

“…Option number one: use an ICU ventilator, and place a device between the endotracheal tube and patient that vaporizes agent at the Y-piece and minimizes waste by reflecting part of the exhaled agent back during the next inspiration using a charcoal filter (AnaConDa, Mirus) [3][4][5][6][7][8][9]; some loss is obligatory to allow the partial pressure to be decreased at a sufficiently rapid rate. Any device added at the patient-machine interface (= at the Y-piece of the breathing system) is bound to add resistance and/or dead space-and thus to increase the work of breathing.…”