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Cardiopulmonary effects of positive end-expiratory pressure during one-lung ventilation in anesthetized dogs with a closed thoracic cavity

Miriam Riquelme DVM1, Eric Monnet DVM, PhD2, Simon T. Kudnig BVSc, MVS, MS3,4, James S. Gaynor DVM, MS5,6, Ann E. Wagner DVM, MS7, Denise Corliss8, and M. D. Salman BVMS, PhD9
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  • 1 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1601.
  • | 2 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1601.
  • | 3 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1601.
  • | 4 Present address is 6651 Backlick Rd, Springfield, VA 22150.
  • | 5 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1601.
  • | 6 Present address is 5752 N Academy Blvd, Colorado Springs, CO 80918.
  • | 7 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1601.
  • | 8 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1601.
  • | 9 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1601.

Abstract

Objective—To evaluate the effects on oxygen delivery (DO2) of 2.5 and 5 cm H2O of positive end-expiratory pressure (PEEP) applied to the dependent lung during one-lung ventilation (OLV) in anesthetized dogs with a closed thoracic cavity.

Animals—7 clinically normal adult Walker Hound dogs.

Procedure—Dogs were anesthetized, and catheters were inserted in a dorsal pedal artery and the pulmonary artery. Dogs were positioned in right lateral recumbency, and data were collected during OLV (baseline), after application of 2.5 cm H2O of PEEP for 15 minutes during OLV, and after application of 5 cm H2O of PEEP for 15 minutes during OLV. Hemodynamic and respiratory variables were analyzed and calculations performed to obtain DO2, and values were compared among the various time points by use of an ANOVA for repeated measures.

Results—PEEP induced a significant decrease in shunt fraction that resulted in a significant increase in arterial oxygen saturation. However, it failed to significantly affect arterial oxygen content (CaO2) or cardiac output. Thus, DO2 was not affected in healthy normoxemic dogs as a net result of the application of PEEP.

Conclusions and Clinical Relevance—The use of PEEP during OLV in anesthetized dogs with a closed thoracic cavity did not affect DO2. Use of PEEP during OLV in dogs with a closed thoracic cavity is recommended because it does not affect cardiac output and any gain in CaO2 will be beneficial for DO2 in critically ill patients. (Am J Vet Res 2005;66:978–983)

Abstract

Objective—To evaluate the effects on oxygen delivery (DO2) of 2.5 and 5 cm H2O of positive end-expiratory pressure (PEEP) applied to the dependent lung during one-lung ventilation (OLV) in anesthetized dogs with a closed thoracic cavity.

Animals—7 clinically normal adult Walker Hound dogs.

Procedure—Dogs were anesthetized, and catheters were inserted in a dorsal pedal artery and the pulmonary artery. Dogs were positioned in right lateral recumbency, and data were collected during OLV (baseline), after application of 2.5 cm H2O of PEEP for 15 minutes during OLV, and after application of 5 cm H2O of PEEP for 15 minutes during OLV. Hemodynamic and respiratory variables were analyzed and calculations performed to obtain DO2, and values were compared among the various time points by use of an ANOVA for repeated measures.

Results—PEEP induced a significant decrease in shunt fraction that resulted in a significant increase in arterial oxygen saturation. However, it failed to significantly affect arterial oxygen content (CaO2) or cardiac output. Thus, DO2 was not affected in healthy normoxemic dogs as a net result of the application of PEEP.

Conclusions and Clinical Relevance—The use of PEEP during OLV in anesthetized dogs with a closed thoracic cavity did not affect DO2. Use of PEEP during OLV in dogs with a closed thoracic cavity is recommended because it does not affect cardiac output and any gain in CaO2 will be beneficial for DO2 in critically ill patients. (Am J Vet Res 2005;66:978–983)