Simple On-Site Assembled Blower-Mister Device Provides Sufficient Humidification and Visualization in Off-Pump Surgery

Comparative Analysis of Irrigation Mist and CO2 vs. Direct CO2 Blower in On-Pump Coronary Artery Bypass Grafting Anastomosis: Efficacy, Efficiency, and Fibrillation upon De-Clamping and Micro-Embolic Gas Activity Incidence

Background and Objectives: In coronary artery bypass grafting (CABG) on pump, achieving optimal visualization is critical for surgical precision and safety. The use of blowers to clear the CABG anastomosis poses risks, including the formation of micro-embolic gas bubbles, which can be insidious and increase the risk of cerebral or myocardial complications. This retrospective study compares the effectiveness of the use of irrigation mist and CO2 versus a direct CO2 blower without irrigation in terms of visualization, postoperative fibrillation, and micro-embolic gas activity. Materials and Methods: The study involved 40 patients who underwent on-pump CABG, with 20 patients assigned to the irrigation mist and CO2 group (ClearView™) and 20 to the direct CO2 blower group. Primary outcomes included the quality of intraoperative visualization, the incidence of fibrillation at aortic de-clamping, and the presence of micro-embolic gas activity detected via transesophageal echocardiography (TEE) in the cardiac chambers. Results: Patients in the irrigation mist and CO2 group experienced superior visualization and reduced tissue desiccation. Fibrillation at the time of aortic de-clamping occurred in two patients (10%) using the irrigation mist and CO2, compared to eight patients (40%) using the direct CO2 blower. Additionally, TEE monitoring revealed lower levels of micro-embolic gas activity in the irrigation mist and CO2 group, indicating a potential reduction in gas embolization risk. Conclusions: The irrigation mist and CO2 system not only provides enhanced visualization during CABG but also significantly reduces the incidence of fibrillation during aortic de-clamping and micro-embolic gas activity. These findings suggest improved patient safety and outcomes, highlighting the irrigation mist and CO2 system as a potentially safer alternative to direct CO2 blowing in the context of myocardial revascularization.

Effect of blower-mister devices on vasoreactivity of coronary artery bypass grafts

OBJECTIVE

Potential disadvantages, such as lower graft patency rates, that could lead to the need for more subsequent revascularization after off-pump coronary artery bypass grafting are discussed. One mechanism may involve endothelial damage originating from tools to facilitate a bloodless surgical field during anastomosis. We investigated the effect of the use of a blower-mister device on in vitro endothelial and contractile functions of human internal thoracic arteries and greater saphenous veins.

METHODS

The distal ends of both bypass graft types were exposed to the air and water stream of the device for 10 minutes, representing the usual time needed for completion of an anastomosis using the off-pump technique. Vessel segments of both groups were cut into 4-mm rings and stored in a modified Krebs-Henseleit solution. Contraction responses to U44619 and relaxation responses to acetylcholine, substance P, papaverine, and nitroprusside were evaluated.

RESULTS

Forty-eight artery ring segments from 8 patients were studied. Absolute maximum contraction to U44619 was significantly less in rings subjected to the blower-mister device than in controls (internal thoracic artery: 17.17 ± 2.57 mN vs 8.67 ± 4.54 mN, P < .048; greater saphenous vein: 28.33 ± 9.71 mN vs 11.42 ± 7.97 mN, P < .026). Control rings had significantly greater endothelium-dependent relaxation response to acetylcholine (mean difference 29.2% ± 3.4%, P < .001), whereas those subjected to the blower-mister device had reduced responses. Endothelium-independent relaxation to nitroprusside was not significantly different among the groups.

CONCLUSIONS

Vessels exposed to the air and water stream of a blower-mister device showed a reduced vasoreactivity. This effect should be studied further, especially if it contributes to lower graft patency rates in off-pump surgery.

Flooding With Carbon Dioxide Prevents Airway Fire Induced by Diathermy During Open Tracheostomy

BACKGROUND

Open tracheostomy is commonly performed during head and neck surgery, and in critically ill patients. Diathermy-induced airway fire during tracheotomy is rare but may have grave implications. Recommendations to minimize this risk are not always practical. We hypothesized that flooding the surgical field with carbon dioxide is an effective technique in preventing fire.

METHODS

We cut through the trachea of two pigs using diathermy while ventilating with pure oxygen five times with, and five times without, simultaneous flushing of the surgical field with carbon dioxide at 10 L/min. To increase the amount of oxygen in the airway and the likelihood of fire,we deliberately deflated the endotracheal cuff to simulate cuff rupture.

RESULTS

Five times out of five, fire was induced when the diathermy cut through the tracheal wall with no carbon dioxide being used. Five times out of five, fire was not induced when carbon dioxide was used. The difference was significant (p < 0.008).

CONCLUSIONS

Flooding the surgical site with carbon dioxide effectively prevents fire during open tracheostomy using diathermy.