Profiles of resistance to breathing in spontaneously ventilating anaesthetised dogs attached to an Ayre’s T-piece

Chemonges, Saul (2015) Profiles of resistance to breathing in spontaneously ventilating anaesthetised dogs attached to an Ayre’s T-piece. Online Journal of Veterinary Research, 19 1: 15-25.

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Author Chemonges, Saul
Title Profiles of resistance to breathing in spontaneously ventilating anaesthetised dogs attached to an Ayre’s T-piece
Journal name Online Journal of Veterinary Research   Check publisher's open access policy
ISSN 1328-925X
Publication date 2015-01-08
Year available 2015
Sub-type Article (original research)
Open Access Status
Volume 19
Issue 1
Start page 15
End page 25
Total pages 11
Place of publication Daisy Hill, QLD Australia
Publisher Pestsearch International
Collection year 2016
Language eng
Formatted abstract
Resistance to breathing is a primary consideration when determining the choice of patient anaesthesia breathing apparatus. To date however, there are limited studies that have categorically quantified resistance to breathing due to specific breathing apparatus in veterinary patients. The aim of this study was to assess the relationship between resistance to breathing, body weight (BW) and fresh gas flow in dogs attached to an Ayre’s T-piece as proof-of-principle. Eight healthy dogs of mixed breeds and age ranging from 6.8-17 kg were anaesthetised by intravenous injection of 2.5% sodium thiopentone at a bolus dose of 12 mg/kg and then endotracheally intubated. The dogs were initially attached to a circle absorber before switching to an Ayre’s T-piece for maintenance of general anaesthesia with 2.5% halothane vapour in oxygen. Resistance to breathing was measured within the endotracheal tube connector using a pressure transducer connected to a pressure-calibrated module. Resistance to breathing was a function of the patient’s body weight. Interestingly, the increase in resistance to breathing corresponded to fresh gas flow to a point of critical fresh gas flow of 0.6 L/min, and then it began to decrease despite increasing fresh gas flow. It has been demonstrated that at very low fresh gas flow, the resistance to breathing is elevated which later eases considerably with increasing fresh gas flow until a continuum is reached. The Ayres’ T-Piece functions best at 2.0 L/min for small to medium sized dogs and there is no benefit to the patient or the clinician in exceeding this fresh gas flow. It is suggested that future studies should compare the various types and sizes of T-piece systems and determine if size influences the magnitude of Resistance to breathing. Future studies on resistance to breathing could also consider enrolling candidates with respiratory pathology. 
Keyword Resistance to breathing
Ayres T Piece
Fresh gas flow
Dogs
Anaesthesia
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
School of Veterinary Science Publications
 
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Created: Fri, 13 Mar 2015, 23:18:15 EST by Saul Chemonges on behalf of School of Veterinary Science