OBJECTIVE: To compare the effects of two fractions of inspired oxygen (FiO(2)) (0.4 and 1) on lung aeration and gas exchange during general anaesthesia in cats. STUDY DESIGN: Randomized, blinded, controlled study. ANIMALS: Thirty healthy, mixed breed, client owned female cats. MATERIALS AND METHODS: Cats were premedicated intramuscularly with acepromazine (0.03 mg kg(-1)) and medetomidine (0.015 mg kg(-1)). Anaesthesia was induced with propofol (5 mg kg(-1)) and, after orotracheal intubation, maintained with isoflurane carried by either 100% oxygen (G100, n=15) or an oxygen-air mixture with 40% oxygen (G40, n=15). All cats were placed in dorsal recumbency and breathed spontaneously throughout the entire procedure. Following surgery (ovariectomy), a spiral computed tomography (CT) of the thorax was performed, arterial oxygen (PaO(2)) and carbon dioxide (PaCO(2)) tensions were measured and alveolar-arterial gradient of oxygen [P(A-a)O(2) ] calculated. The CT images were analysed for lung aeration by the analysis of radiograph attenuations (Hounsfield units, HU), according to the following classification: hyperinflated area (-1000 to -900 HU), normally aerated area (-900 to -500 HU), poorly aerated area (-500 to -100 HU) and non-aerated area (-100 to +100 HU). The groups were compared using one-way anova. RESULTS: Compared to G100, the normally-aerated lung area was significantly greater and the poorly-aerated and non-aerated areas were significantly smaller in G40. PaCO(2) was similar in both groups. PaO(2) and P(A-a)O(2) were significantly higher in G100. In both groups, pulmonary atelectasis developed preferentially in the caudal lung fields. CONCLUSION: In cats anaesthetised with isoflurane, the administration of an FiO(2) of >0.9 significantly impaired lung aeration and gas exchange as compared to an FiO(2) of 0.4. CLINICAL RELEVANCE: An FiO(2) of 0.4 may better preserve lung aeration and gas exchange in anaesthetised spontaneously breathing cats but monitoring is essential to ensure oxygenation is adequate.
OBJECTIVE: To compare the effects of two fractions of inspired oxygen (FiO(2)) (0.4 and 1) on lung aeration and gas exchange during general anaesthesia in cats. STUDY DESIGN: Randomized, blinded, controlled study. ANIMALS: Thirty healthy, mixed breed, client owned female cats. MATERIALS AND METHODS:Cats were premedicated intramuscularly with acepromazine (0.03 mg kg(-1)) and medetomidine (0.015 mg kg(-1)). Anaesthesia was induced with propofol (5 mg kg(-1)) and, after orotracheal intubation, maintained with isoflurane carried by either 100% oxygen (G100, n=15) or an oxygen-air mixture with 40% oxygen (G40, n=15). All cats were placed in dorsal recumbency and breathed spontaneously throughout the entire procedure. Following surgery (ovariectomy), a spiral computed tomography (CT) of the thorax was performed, arterial oxygen (PaO(2)) and carbon dioxide (PaCO(2)) tensions were measured and alveolar-arterial gradient of oxygen [P(A-a)O(2) ] calculated. The CT images were analysed for lung aeration by the analysis of radiograph attenuations (Hounsfield units, HU), according to the following classification: hyperinflated area (-1000 to -900 HU), normally aerated area (-900 to -500 HU), poorly aerated area (-500 to -100 HU) and non-aerated area (-100 to +100 HU). The groups were compared using one-way anova. RESULTS: Compared to G100, the normally-aerated lung area was significantly greater and the poorly-aerated and non-aerated areas were significantly smaller in G40. PaCO(2) was similar in both groups. PaO(2) and P(A-a)O(2) were significantly higher in G100. In both groups, pulmonary atelectasis developed preferentially in the caudal lung fields. CONCLUSION: In cats anaesthetised with isoflurane, the administration of an FiO(2) of >0.9 significantly impaired lung aeration and gas exchange as compared to an FiO(2) of 0.4. CLINICAL RELEVANCE: An FiO(2) of 0.4 may better preserve lung aeration and gas exchange in anaesthetised spontaneously breathing cats but monitoring is essential to ensure oxygenation is adequate.
Authors: Laura A Wilding; Joe A Hampel; Basma M Khoury; Stacey Kang; David Machado-Aranda; Krishnan Raghavendran; Jean A Nemzek Journal: J Am Assoc Lab Anim Sci Date: 2017-03-01 Impact factor: 1.232
Authors: Marcela L Machado; Joao H N Soares; Bruno H Pypendop; Antonio J A Aguiar; Christina Braun; Gabriel C Motta-Ribeiro; Frederico C Jandre Journal: Front Vet Sci Date: 2022-05-04
Authors: Alessandro R C Martins; Aline M Ambrósio; Denise T Fantoni; Ana Carolina B C F Pinto; Lenin Arturo Villamizar-Martinez; João H N Soares; Denise A Otsuki; Luiz Marcelo S Malbouisson Journal: Front Vet Sci Date: 2022-04-01