Systemic oxygen extraction can be improved during repeated episodes of cardiac tamponade |
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Authors: | Haibo Zhang Herbert Spapen Malik Benlabed Jean-Louis Vincent |
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Affiliation: | 1. School of Chemical, Petroleum and Gas Engineering, Semnan University, Semnan, Iran;2. Nanotechnology Research Center, Research Institute of Petroleum Industry, Tehran, Iran;3. University of Birjand, Birjand, Iran;1. School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab of Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, PR China;2. Dalian Research Institute of Petroleum and Petrochemicals, SINOPEC, Dalian 116045, PR China;1. University Hospital for Infectious Diseases;2. Department of Infectious Diseases, Zagreb University School of Medicine, Zagreb, Croatia;1. Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science and Technology, Hebei University, Baoding, 071002, China;2. College of Quality Technology Supervision, Hebei University, Baoding, 071002, China;3. College of Chemistry and Material Science, Hebei Normal University, No. 20 Rd. East of 2nd Ring South, Yuhua District, Shijiazhuang City, Hebei Province, 050024, China;4. Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources in Hainan University, China |
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Abstract: | We used a tamponade model to study the relationship between oxygen uptake (VO2) and oxygen delivery (Do2) during successive, reversible decreases in blood flow. In 7 pentobarbital-anesthetized and mechanically ventilated dogs, a catheter was introduced via a left thoracotomy into the pericardium to inject and to withdraw saline. Each experiment consisted of three steps. First, cardiac output was reduced by successive pericardial fluid injections until 4 to 6 data points were obtained in the dependent region of the o2/o2 plot (step 1). Second, cardiac output was restored by progressive withdrawal of pericardial fluid (step 2). Third, cardiac output was lowered again by reinjection of fluid into the pericardium until death (step 3). Expired gases were collected for determination of 2. In each animal, critical o2 (o2crit), below which 2 became o2 dependent, was determined from a plot of 2 versus o2. When releasing tamponade, 2 was restored to baseline. For the 3 steps, o2crit were 10.5 ±- 2.2 mL/kg/min in step 1, 9.8 ±- 1.8 mL/kg/min in step 2, and 8.3 ±- 1.9 mL/kg/min in step 3 (P < .01 v step 1; P < .05 v step 2, respectively). There was no significant difference in o22 at o2crit for the three steps. Hence, critical oxygen extraction ratio (ERo2crit) increased from 60% ±- 12% in step 1 to 64% ± 11 % in step 2 (not significant) and to 73% ±- 12% in step 3 (P < .01). The 2/o2 dependency slope was also steeper in step 3 than in step 1 (0.77 ± 0.31 v 0.54 ±- 0.20, P < .05). A progressive decrease in arterial and in mixed venous pH was observed during the experiment. We conclude that a decrease in 2 associated with an acute reduction in blood flow can be readily reversible. When the procedure is repeated, a progressive increase in oxygen extraction capabilities is observed. This reversible tamponade model is potentially suitable to induce several hypoxic episodes in the same animal. |
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