CP22 Gas Embolism
PROCEDURE FOR MASSIVE GAS EMBOLISM AS OUTLINED IN “THE PRACTICE OF CARDIAC ANESTHESIA” LITTLE , BROWN; 1ST EDITION (1990
- Stop cardiopulmonary bypass immediately.
- Steep Trendelenberg position.
- Remove aortic cannula vent air from aortic cannulation site.
- Deair arterial cannula and pump line.
- Institute hypothermic retrograde operator vena cava (SVC) perfusion by connecting arterial pump line to the SVC cannula with caval tape tightened. Blood at 20-24*C is injected into SVC at 1-2L/min or more, and air plus blood is drained from aortic cannulation site to the pump.
- Carotid compression is performed intermittently during retrograde SVC perfusion to allow retrograde purging of air from the vertebral arteries.
- Maintain retrograde SVC perfusion for at lease 1-2 min. Continue for an additional 1-2 min if air continues to exit from aorta.
- In extensive systemic air injection accidents in which emboli to splanchnic, renal, or femoral circulation are suspected, retrograde inferior vena cava perfusion may be performed after head heairing procedures are completed. This is performed while the carotid arteries are clamped and the patient is in head-up position to facilitate removal of air throught the aortic root vent, but prevent reembolization of the brain.
- When no additional air can be expelled, resume anterograde CPB, maintain hypothermial at 20*C for at least 40-50 min. Lowering patient temperature is important because increased gas solubility helps to resorb bubbles and because decreased metabolic demands may limit ischemic damage before bubble resorption.
- Induce hepertension with vasoconstrictor drugs. Hydrostatic pressure shrinks bubbles; also, bubbles occluding arterial bifurcations are pushed into one vessel, opening the other branch.
- Express coronary air by massage and needle venting.
- Steroids may be administered, although this is controversial; the usual dose of methylprednisolone is 30mg/kg.
- Barbiturate come should be considered if the myocardium will be able to tolerate the significant negative inotropy. Thiopental 10mg/kg loading dose plus 1-3 mg/kg/h infusion may be used empirically. If EEG monitoring is available, titration of barbiturate to an EEF burst/suppression (1 burst/min) pattern is preferable.
- Patient is weaned from CPB
- Continue ventilating patient with 100% O2 for at least 6 h to maximize blood alveolar gradient for elimination of N2.
- Hyperbaric chamber can accelerate resorption of residual bubbles. However, the risk of moving a critically ill patient must be weighed against the potential benefits.