Ablating entraining

Things can go awry when fluid or air is infused into the body. Recently there was a case when sudden and profound hypoxaemia occurred during endometrial ablation. Glycine was being infused and the ablating diathermy had been bubbling away. The subsequent serum sodium was not low, so water overload seemed unlikely. The saturation came good quite quickly so it seemed likely that bubbles from the diathermy or irrigation fluid entered the venous system through the newly exposed surface of the myometrium. Over the years there have been several cases of probable gas embolism during hysteroscopic surgery, and there was a move to saline distension from CO2 as a result. However gas is generated from the ablating diathermy and this too can enter the systemic and pulmonary venous circulation.

What is the preferred anaesthesia technique for endometrial ablation (EA)? Prostatectomy is often done with spinal anaesthesia; the ability to detect cerebral symptoms may warn of developing hyponatremia. This has not been a popular choice for EA, mostly because the patients are generally younger and healthier and are more averse to having spinal anaesthesia. Instead, LMA anaesthesia with spontaneous ventilation is probably the most common choice. Gehring et al in Acta Anaesthesiol Scand. 1999 Apr concluded that the absorption of irrigant is more marked with spinal anesthesia than IPPV GA due to the lower CVP in the former. It is conceivable that the CVP could be lower in spontaneously breathing under sevoflurane anaesthesia due to the combined effects of airway resistance, snatchy chest wall and diaghragm movement and reduced venous tone. It may be that controlled ventilation is the technique of choice for endometrial ablation as it may reduce the risk of entraining fluid or gas