Journal of Clinical Monitoring and Computing

, Volume 32, Issue 4, pp 639–646 | Cite as

Halving the volume of AnaConDa: initial clinical experience with a new small-volume anaesthetic reflector in critically ill patients—a quality improvement project

  • Hagen BombergEmail author
  • Franziska Meiser
  • Sarah Zimmer
  • Martin Bellgardt
  • Thomas Volk
  • Daniel I. Sessler
  • Heinrich V. Groesdonk
  • Andreas Meiser
Original Research


AnaConDa-100 ml (ACD-100, Sedana Medical, Uppsala, Sweden) is well established for inhalation sedation in the intensive care unit. But because of its large dead space, the system can retain carbon dioxide (CO2) and increase ventilatory demands. We therefore evaluated whether AnaConDa-50 ml (ACD-50), a device with half the internal volume, reduces CO2 retention and ventilatory demands during sedation of invasively ventilated, critically ill patients. Ten patients participated in this cross-over protocol. After sedation with isoflurane via ACD-100 for 24 h, the 5-h observation period started. During the first hour, ACD-100 was used; for the next 2 h, ACD-50; and for the last 2 h, ACD-100 was used again. Sedation was titrated to Richmond Agitation and Sedation Scale (RASS) score − 3 to − 4 and a processed electroencephalogram (Narcotrend Index, Narcotrend-Gruppe, Hannover, Germany) was recorded. Minute ventilation, CO2 elimination, and isoflurane consumption were compared. All patients were deeply sedated (Narcotrend Index, mean ± SD: 38 ± 10; RASS scores − 3 to − 5) and breathed spontaneously with pressure support throughout the observation period. Infusion rates of isoflurane and opioid, either remifentanil or sufentanil, as well as ventilator settings were unchanged. Minute ventilation and end-tidal CO2 were significantly reduced with the ACD-50, respiratory rate remained unchanged, and tidal volume decreased by 66 ± 43 ml. End-tidal isoflurane concentrations were also slightly reduced while haemodynamic measures remained constant. The ACD-50 reduces the tidal volume needed to eliminate carbon dioxide without augmenting isoflurane consumption.


Anaesthesic reflection Carbon dioxide reflection Dead space Inhalation sedation Isoflurane 



The AnaConDa-50 ml reflectors were kindly provided by the manufacturer Sedana Medical, Uppsala, Sweden. The sponsor was neither involved in data acquisition, analysis, or the design of the protocol, nor did they review the submitted manuscript which was entirely prepared by the authors.

Compliance with ethical standards

Conflict of interest

The authors declare that they did not receive any funding for realisation of this study. AM and TV received honoraria and travel expenses for lectures from Sedana Medical (Uppsala, Sweden). AM has been a consultant for Sedana Medical (Uppsala, Sweden). AM has received honoraria and travel expenses for lectures as well as research funding from Pall Medical (Dreieich, Germany).

Ethical approval

Informed consent and Human participants were involved.

Supplementary material

10877_2018_146_MOESM1_ESM.docx (17 kb)
Supplementary material 1 (DOCX 16 KB)


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Copyright information

© Springer Science+Business Media B.V., part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Anaesthesiology, Intensive Care Medicine and Pain Medicine, Saarland University Medical CentreUniversity of SaarlandHomburgGermany
  2. 2.Department of Anaesthesiology and Intensive Care Medicine, St. Josef Hospital, Katholisches Klinikum Bochum, University HospitalRuhr-University of BochumBochumGermany
  3. 3.Department of Outcomes ResearchAnesthesiology Institute, Cleveland ClinicClevelandUSA

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