Carbon dioxide de‐airing in cardiac surgery

Abstract

(ENG)Background: The risks connected with the presence of air microemboli in open-heart surgery, have recently been emphasized by reports that their number is correlated with the degree of postoperative neuropsychological disorder. Insufflation of carbon dioxide (CO 2 ) into the chest wound is used in open-heart surgery to de-air the heart and great vessels. A new insufflation device, a gas-diffuser, was compared with traditional devices for de-airing in an experimental wound model. Finally, to assess the clinical value of CO 2 insufflation into the cardiothoracic wound, the effect of such insufflation on the incidence and behavior of microemboli in the heart and ascending aorta was studied under the conditions of a randomized clinical trial. Methods: In a cardiothoracic wound model, a full-size torso, the degree of air displacement achieved by the gas-diffuser, was compared with that of a 2.5 mm open-ended tube, a 6.35 mm open-ended tube, a multi-perforated catheter, and a gauze sponge, respectively, during steady state. The influence of suction, varying CO 2 flow rates, an open pleural cavity, exposure to fluids and the position of the device were also evaluated. De-airing was assessed by measuring the remaining air content at the right atrium. In the trial, twenty (20) patients undergoing single valve surgery were randomly divided into two groups. Ten patients were insufflated with CO 2 via a gas-diffuser and ten were not. Microemboli were ascertained by intraoperative transesophageal echocardiography (TEE) from release of the aortic cross-clamp until 20 minutes after end of cardiopulmonary bypass (CPB). Results: During steady state, the gas-diffuser produced efficient air displacement in the wound cavity model at CO 2 flows of ³5 l/min (£0.65% remaining air), while the 2.5mm and 6.35mm open-ended tube were much less efficient with ³82% and >19.5% remaining air, respectively, at 2.5-10 l/min CO 2 flows (p<0.001). When using the gas-diffuser, an open pleural cavity prolonged the time needed to obtain a high degree of air displacement in the wound cavity (p=0.001). With suction of 10 l/min the median air content was still low (£0.50%) at a simultaneous CO 2 flow of 10 l/min. Conversely, suction of 25 l/min caused a marked increase in air content both at a CO 2 flow of 5 and 10 l/min (p<0.001). When exposed to fluid, the gauze sponge and the multi-perforated catheter immediately became inefficient (70% and 96% air, respectively), whereas the gas-diffuser remained efficient (0.4% air). The two patient groups did not differ in clinical parameters. The median number of microemboli registered during the whole study period was 161 in the CO 2 group versus 723 in the control-group (p<0.001). Corresponding numbers for the left atrium were 69 versus 340 (p<0.001), left ventricle 68 versus 254 (p<0.001), ascending aorta 56 versus 185 (p<0.001). In the CO 2 group the median number of detectable microemboli after CPB fell to zero 7 minutes after CPB versus 19 minutes in the control group (p<0.001). Conclusion:The ...

Direct visualization of carbon dioxide field flooding: Optical and concentration level comparison of diffusor effectiveness

“…These observations corroborate the findings of Svenarud with gas samplings. 20 Only with the lowest flow rate (1 SLPM) or with the application of suction, does the CarbonAid max out at lower CO 2 concentrations, especially in the region of an aorta incision. The 1 SLPM flow rate in general is unusable for air emboli protection, as explained earlier, because it takes too much time to establish a steady atmosphere and the use of suction would immediately eliminate all the gas.…”

“…6,7,19 With the development of the first commercial CO 2 diffusor, a range of laboratory studies were performed that demonstrated that flow rate, presence of suction, and design of the diffusor make a notable difference in the remaining air content in the thorax. 20 In this article, we aim to contribute to the better understanding of CO 2 field flooding via direct visualization of the gas mixing, combined with high-speed measurements of the CO 2 concentration directly inside a thorax model.…”

Size of Left Cardiac Chambers Correlates with Cerebral Microembolic Load in Open Heart Operations

“…Deairing technologies are actively investigated at present as well [ 9 , 17 , 18 ]. Carbon dioxide insufflation into wound cavity appears to be neuroprotective.…”

“…Air tends to accumulate in the highest parts of the heart including left ventricular apex, left atrial appendix, and the upper wall of the left atrium [ 9 ]. Air bubbles are mobilized into the arterial bed not only during and after the heart resumes function and CPB is stopped.…”