Paradoxical gas embolism during hysteroscopy
Hobart, Australia
* E-mail: ssherlock{at}dhhs.tas.gov.au
Editor—I read with great interest the report by Rademaker and colleagues1 of paradoxical gas embolism during hysteroscopy. I have two questions I wish to pose, having had a similar case myself.2 First, since this was a hysteroscopy using normal saline as the distension medium (thought to lower the risk compared with CO2), where did the authors suspect the gas to have originated from. There have been suggestions that inadequate purging of air from the equipment can cause embolism. Did the authors suspect this may have been the case? Secondly, and perhaps more importantly, I question why the authors did not consider hyperbaric oxygen therapy (HBO). Urgent exposure to HBO is the current accepted therapy for cerebral gas embolism.3 4 With a confirmed diagnosis of arterialization of gas via transthoracic echocardiography, it should have been considered. The consequences of arterial embolism, as the authors pointed out, include hemiparesis, blindness, and coma. A previous study5 suggests that the outcome is worst when treatment is delayed (more than 6 h) and arterial gas embolism is worse than venous embolism (recovery 35% vs 67%). Was hyperbaric therapy unavailable or discounted for some reason?
Amsterdam, The Netherlands
* E-mail: b.m.p.rademaker{at}olvg.nl
Editor—In response to the two questions from Dr Sherlock, I have the following comments. First, regarding the possibility of improper purging of air from the hysteroscopic instruments, we used normal saline as a distension medium and carefully purged air from all lines and hysteroscopic instruments. After cervical dilation, the exposure of the open cervix to room air was kept to a minimum leaving the cervix closed using a tenaculum forceps. A continuous out-flow system was used so that the distension medium is refreshed actively and bubbles and debris are flushed away. We considered it unlikely that air entrainment played an important role in our case. For that reason, we think that the development of gas produced by the electrosurgical vaporization of myomas, fibroids, endometrial, uterine tissue, or both is much more important factor. Indeed, Munro and colleagues6 demonstrated in vitro that hysteroscopic electrosurgical vaporization using either monopolar or bipolar diathermia results in the production of significant quantities of the highly soluble gases: hydrogen, carbon monoxide, and carbon dioxide. The second question addressed the use of HBO in the case of arterial embolism. Indeed, HBO is considered the main stay of therapy in arterialization of gas, especially when cerebral gas embolism is accompanied by neurological deficits. Fortunately, our patient did not develop neurological sequelae. She recovered uneventfully after a period of supportive measures using an hour of mechanical ventilation with 100% of oxygen. As Dr Sherlock states correctly, the use of HBO should always be considered when neurological deficits are present.7 However, HBO treatment is not available in every hospital and its apparent lack of availability may hamper its use. Indeed, in our hospital, we do not have HBO and we have to transport the patient 10 km to the nearest HBO facility. In my opinion, the need for HBO in a possibly unstable patient has to be weighed against the risks of transportation and should therefore probably be restricted for patients having apparent neurological deficits. Specific measurements for the treatment of coronary artery emboli that have been advocated include, in addition to HBO, bubble removal with a vacuum extraction catheter.8 9
References
1 Rademaker BMP, Groenman FA, van der Wouw PA, Bakkum EA. Paradoxical gas embolism by transpulmonary passage of venous emboli during hysteroscopic surgery: a case report and discussion. Br J Anaesth (2008) 101:230–3.
2 Sherlock S, Shearer WA, Buist M, Rasiah R, Edwards A. Carbon dioxide embolism following diagnostic hysteroscopy. Anaesth Intensive Care (1998) 26:674–6.[Web of Science][Medline]
3 Jorgenson TB, Sorensen AM, Jansen EC. Iatrogenic systemic air embolism treated with hyperbaric oxygen therapy. Acta Anaesthesiol Scand (2008) 52:566–8.[Web of Science][Medline]
4 Bitterman H, Melamed Y. Delayed hyperbaric treatment of cerebral air embolism. Isr J Med Sci (1993) 29:22–6.[Web of Science][Medline]
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6 Munro MG, Weisberg M, Rubinstein E. Gas and air embolization during hysteroscopic electrosurgical vaporization: comparison of gas generation using bipolar and monopolar electrodes in an experimental model. J Am Assoc Gynecol Laparosc (2001) 8:488–94.[CrossRef][Web of Science][Medline]
7 Murphy BP, Harford FJ, Cramer FS. Cerebral air embolism resulting from invasive medical procedures. Treatment with hyperbaric oxygen. Ann Surg (1985) 201:242–5.[Web of Science][Medline]
8 Patterson MS, Kiemeneij F. Coronary air embolism treated with aspiration catheter. Heart (2005) 91:e36.
9 Engelmann U, Minden H, Stock UA, et al. Late air embolism with interventional removal after isolated coronary artery bypass grafting. J Thorac Cardiovasc Surg (2006) 131:1403–4.
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