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Type of publication: Diploma Thesis
Type of document:

Year: 2010

Authors: Layr, Isabella

Title: Post Hoc "Single Breath Diagram For CO2 (SBDCO2)"- Analyse während der Pferdeanästhesie.

Source: Diplomarbeit, Vet. Med. Univ. Wien, pp. 48.


Auer Ulrike
Schramel Johannes

Schäfer-Somi Sabine
Schramel Johannes

Vetmed Research Units:
University Clinic for Small Animals, Clinical Unit of Anaesthesiology and Perioperative Intensive-Care Medicine

The single-breath-diagram for CO2 (SBD-CO2) ist the graphical presentation of the plot of the expired carbon dioxide concentration versus expired volume and provides valuable information about lung function parameters, such as physiological deadspace, airway deadspace and alveolar deadspace. FOWLER (1948) first divided the CO2 expirogram into three phases. Each phase is related to an anatomic compartment of the respiratory system. Phase I respresents the relatively carbon dioxide free exhaled air of the upper airways. Phase II shows the transition from the expired gas from the proximal conducting airways to the alveolar gas and therefore is characterised by a rapid upswing. Phase III represents the carbon dioxide rich gas expired from the alveoli and is also known as the alveolar plateau. The analysis of the SBD-CO2 is well investigated in humans, but rarely described in veterinary anaesthesia. Especially in horses, whose lung function is due to the animal´s size and weight severly impaired during anaesthesia, it might be a useful tool for continuous monitoring of deadspace. The required signals for creating a SBD-CO2 (Volume and CO2) are measured with spirometry and capnometry. To calculate physiological and alveolar deadspace it is necessary to draw an arterial blood sample and analyse it for PCO2. The aim of this study was to find out, if it is possible to generate a single-breath-diagram for CO2 with the softwareprogram SBCO2Calc (Oberli Engineering, Switzerland) by using the CO2- and volume-signals measured during anaesthesia of a horse with the sidestream Horse-lite-spirometer and the Datex-Ohmeda S/5™-anaesthesia-monitor. The results have been compared to the findings collected with the mainstream revolver-spirometer and the NICO-monitor (Respironics) and with analysis-plus-software (Novametrix Medical Systems Inc.) evaluated signals.

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