Quantification of reservoir bags as airway pressure-limiting devices in a nonrebreathing system

Tamas D Ambrisko; Arnon Gal; Jesus N Sarol Jr; Ashley Mitek; Christina Braun

doi:10.1016/j.vaa.2020.11.004

Quantification of reservoir bags as airway pressure-limiting devices in a nonrebreathing system

Vet Anaesth Analg. 2021 Mar;48(2):205-212. doi: 10.1016/j.vaa.2020.11.004. Epub 2020 Dec 11.

Authors

Tamas D Ambrisko¹, Arnon Gal², Jesus N Sarol Jr³, Ashley Mitek², Christina Braun⁴

Affiliations

¹ Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Electronic address: tambrisko@hotmail.com.
² Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
³ Illinois Biostatistics, Epidemiology and Research Design Core, Interdisciplinary Health Sciences Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
⁴ Anaesthesiology and Perioperative Intensive-Care Medicine, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria.

PMID: 33431268
DOI: 10.1016/j.vaa.2020.11.004

Abstract

Objective: To evaluate the influence of reservoir bag types, volumes and previous use on the peak pressures (Pmax) and the times to develop 30 cmH₂O pressure (P30) within a nonrebreathing system with a closed adjustable pressure-limiting (APL) valve.

Study design: In vitro study using three-way factorial design with repeated measure on one factor.

Subjects: A total of 75 new anesthesia reservoir bags (five types, three volumes, five bags from each type × volume). The bag types were reusable latex (RL), disposable latex (DL) and three disposable neoprene (DN-1, DN-2 and DN-3).

Methods: Each bag was tested three times (treatments): new, after prestretching and 1 week later. The bags were attached to a Bain system and anesthesia machine with closed APL valve and patient port with O₂ flow 2 L minute^-1 until Pmax was reached. The Pmax and time to reach P30 values were determined from recorded pressure traces. General linear mixed model analysis was used to examine the effects of bag type, volume and treatment. One-sided 95% upper prediction limits of Pmax were calculated to test the null hypothesis that predicted Pmax of new bags would be ≥ 50 cmH₂O for each factor combination.

Results: RL bags were the least and DN-3 bags were the most compliant. Prestretching increased compliance in all bag types. Smaller bags of RL, DL and DN-1 were less compliant than larger ones. The predicted Pmax values were < 50 cmH₂O only for DN-3 bags after prestretching. The time to reach P30 was critically low when using 0.5 L bags (median 17 seconds).

Conclusions and clinical relevance: To minimize the risk of barotrauma, highly compliant reservoir bags (e.g. DN-3) are recommended and reusable bags should be avoided. Bags should be prestretched before first use, 0.5 L bags should be avoided and fresh gas flow minimized.

Keywords: APL valve; Bain circuit; anesthetic accident; excessive airway pressure; nonrebreathing system; reservoir bag.

MeSH terms

Anesthesia* / veterinary
Anesthesiology*
Animals
Respiration, Artificial / veterinary