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

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.