EFFECTS OF CARBON-DIOXIDE EMBOLISM WITH NITROUS-OXIDE IN THE INSPIREDGAS IN PIGLETS

We have compared cardiorespiratory variables in anaesthetized piglets whose lungs were ventilated with oxygen in nitrous oxide (N2O group) o r nitrogen (N group) after right ventricular carbon dioxide boluses (0 .5 or 1 mi kg(-1); n = 12) or slow graded injections (n=6). Boluses af fected all variables studied significantly (P < 0.05) except mean syst olic arterial pressure. Significant changes in PE/(CO2) (P = 0.012) an d Pa-O2 (P = 0.048) values were observed in the N2O group. Changes in Pace, were related to volumes of injected carbon dioxide (P = 0.044). Boluses of 1.0 mt kg(-1) induced severe circulatory collapse in two pi glets in the N2O group. Slow embolization altered respiratory variable s significantly (P < 0.001)). Pa-O2 decreased significantly in the N2O group (P < 0.0001).-Mean pulmonary arterial pressure increased signif icantly over time (P = 0.0001) and lasted longer in the N2O group (P < 0.05). Volumes and time required to induce a 50% increase in mean pul monary arterial pressure differed significantly between groups (P < 0. 05). We conclude that nitrous oxide worsened the effects of rapid and slow carbon dioxide emboli on cardiopulmonary variables. Rapid carbon dioxide embolism altered respiratory and haemodynamic variables, while slow carbon dioxide embolism changed only respiratory variables.