Department of Nephrology University Hospital Dresden Germany Email: kayherbrig{at}aol.com
Sir,
We appreciate the comment by Rao et al., who objected to methylene blue i.p. to demonstrate the peritoneo-pleural leak. The reason for their objection was fear of chemical peritonitis. We agree that a clearly elevated glucose concentration in the pleural effusion might have been sufficient to demonstrate the suspected leak. In this way we found a glucose concentration in the effusion of 22.5 mmol/l, when fresh dialysis solution had been instilled into the peritoneal cavity shortly before. It was during this particular exchange that we added the methylene blue to demonstrate its appearance in the pleural effusion. Thus, we proved the peritoneo-pleural leak twice, which was not strictly necessary. In this respect we fully agree with Rao et al.
However, we do not find sufficient indication for their statement that methylene blue is "... an irritant to the peritoneum ...", which is "... not advisable to use ...". We searched the literature on this issue and we found only the two case reports that are also mentioned in the letter. In addition, methylene blue is used clinically for diagnostic procedures frequently without complications. These procedures are detection of enteric, bronchial or bladder fistulae, as well as chromopertubation in diagnostic laparoscopy [13]. Also, Hosoda et al. [4] diagnosed and successfully treated a pleuroperitoneal communication in a CAPD patient by video-assisted thoracoscopic surgery using methylene blue containing dialysis solution through the PD catheter. Taken together we do not agree with the statement by Rao et al. that i.p. methylene blue administration should in general be avoided in patients treated by peritoneal dialysis.
Conflict of interest statement. None declared.
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