OBJECTIVE: To evaluate the effect of an open-chest condition on oxygen delivery in anesthetized dogs. STUDY DESIGN: Prospective, controlled experimental study. ANIMALS: Eight clinically normal adult Walker Hound dogs weighing 25.6-29.2 kg. METHODS: Eight anesthetized dogs underwent an open-chest operation after the insertion of thoracoscopy cannulae in the lateral chest walls. A Swan Ganz catheter was used to both measure hemodynamic parameters and obtain mixed venous blood samples for blood gas analysis. A dorsal pedal catheter was placed to both measure arterial blood pressure and obtain blood samples for blood gas analysis. Oxygen delivery index and oxygen extraction ratio were calculated. A randomized block anova for repeated measures was used to evaluate the effect of the treatment on hemodynamic and pulmonary parameters. RESULTS: Creation of an open chest did not significantly affect oxygen delivery index (DO(2)I; p = 0.545). It induced a significant decrease in arterial oxygen partial pressure (PaO(2); p = 0.018) and arterial oxygen content (CaO(2); p = 0.025). It induced a significant increase in shunt fraction (p = 0.023), physiologic dead space (p = 0.015), and alveolar-arterial oxygen difference (p = 0.019). Arterial partial pressure of carbon dioxide (PaCO(2); p = 0.766) and arterial hemoglobin oxygen saturation (SaO(2); p = 0.178) were not significantly affected. Diastolic (DPAP; p = 0.050) and mean (MPAP; p = 0.033) pulmonary arterial pressures were significantly increased by opening the chest. Other hemodynamic parameters were not significantly affected. CONCLUSIONS: Opening the thoracic cavity is not detrimental to hemodynamic function and oxygen delivery in normal dogs, although impaired gas exchange does occur. CLINICAL RELEVANCE: Close monitoring of patients is recommended during open-chest thoracoscopy as adverse effects on gas exchange can contribute to hypoxemia.
OBJECTIVE: To evaluate the effect of an open-chest condition on oxygen delivery in anesthetized dogs. STUDY DESIGN: Prospective, controlled experimental study. ANIMALS: Eight clinically normal adult Walker Hound dogs weighing 25.6-29.2 kg. METHODS: Eight anesthetized dogs underwent an open-chest operation after the insertion of thoracoscopy cannulae in the lateral chest walls. A Swan Ganz catheter was used to both measure hemodynamic parameters and obtain mixed venous blood samples for blood gas analysis. A dorsal pedal catheter was placed to both measure arterial blood pressure and obtain blood samples for blood gas analysis. Oxygen delivery index and oxygen extraction ratio were calculated. A randomized block anova for repeated measures was used to evaluate the effect of the treatment on hemodynamic and pulmonary parameters. RESULTS: Creation of an open chest did not significantly affect oxygen delivery index (DO(2)I; p = 0.545). It induced a significant decrease in arterial oxygen partial pressure (PaO(2); p = 0.018) and arterial oxygen content (CaO(2); p = 0.025). It induced a significant increase in shunt fraction (p = 0.023), physiologic dead space (p = 0.015), and alveolar-arterial oxygen difference (p = 0.019). Arterial partial pressure of carbon dioxide (PaCO(2); p = 0.766) and arterial hemoglobin oxygen saturation (SaO(2); p = 0.178) were not significantly affected. Diastolic (DPAP; p = 0.050) and mean (MPAP; p = 0.033) pulmonary arterial pressures were significantly increased by opening the chest. Other hemodynamic parameters were not significantly affected. CONCLUSIONS: Opening the thoracic cavity is not detrimental to hemodynamic function and oxygen delivery in normal dogs, although impaired gas exchange does occur. CLINICAL RELEVANCE: Close monitoring of patients is recommended during open-chest thoracoscopy as adverse effects on gas exchange can contribute to hypoxemia.
Authors: Renata R Rodrigues; Aline M Ambrósio; Aline M Engbruch; Lucas A Gonçalves; Paula A Villela; Ana F Sanchez; Denise T Fantoni Journal: Front Vet Sci Date: 2022-03-15