Explosion of hydrogen gas in the colon during proctosigmoidoscopy

contiguous to the lymphangioma. Thus, true varices might be expected to occur as a result of increased circulatory demand on the portal venous system already com prom ised by the mass of lymphangioma compressing the mesentery. This would be reflected in an increased portal venous pressure which could lead to formation of porto-systemic anastomoses, i.e., varices, in the area of compromised drainage. A pelvic lymphangioma, as in our case, would be expected to produce regional porto-systemic anastomoses involving the superior hemor· rhoidal (portal) venous plexus and the inferior hemorrhoidal (caval) plexus. That the varices were seen in the distal sigmoid and in the upper but not the distal rectum would be consistent with this idea. Also favoring these being varices and not cavernous hemangiomas is the reported low coincidence of other vascular elements with lymphangiomas."2,7 The finding, however, of capillary hemangiomas of the rectosigmoid might suggest the alternative interpretation, that the rectosigmoid lesion was a vascular malformation involving 3 vascular elements: lymphatic, capillary, and venous. Vascular elements other than lymphatic occur with Iymphan-

giomas in so-called hemangio-Iymphomatous hamartomas of the mesentery, but these are extremely rare and have not been associated with cutaneous vascular malformations. 7 As all biopsies previously performed in our case showed only lymphatic elements, we must therefore regard the capillary hemangiomas as an interesting but unexplained accompaniment to what seems most likely to be varices and lymphangiomas of the rectosigmoid colon.

REFERENCES 1, HARKINS GA, SABISTON DC: Lymphangioma in infancy and childhood. Surgery 47:811,1960 2, BILL AH, SUMNER DS: A unified concept of lymphangioma and cystic hygroma, Surg Gyn Obst 120:79, 1965 3, OVIEDO MA, LARSON N, PARENT G: Retroperitoneal and gluteal cystic lymphangioma. Illinois Med J 141 :381, 1972 4. BERANDI RS: Lymphangioma of the large intestine. Dis Colon Rectum 17:265,1974 5. KUPlc EA, EDDY WM: Lymphangioma, a rare pelvic mass lesion. Am J Roentgenol 126:404, 1973 6. ELLIOTT GB, KLiMAN MR, ELLIOT KA: Persistence of Iymphatico-venous shunts at the level of the microcirculation: their relationship to "lymphangioma" of the mesentery. Ann Surg 172:131, 1970 7. FRAGOYANNIS SG, ANAGNOSTOPULOS G: Hemangiolymphomatous hamartoma of the mesentery. Am J Dis Child 128:233. 1974

Explosion of hydrogen gas in the colon during proctosigmoidoscopy John H. Bond, MD Michael levy, MD Michael D. levitt, MD Department of Medicine, Minneapolis VA Hospital 51. Louis Park Medical Center and the University of Minnesota Hospitals Minneapolis, Minnesota

The presence of the combustible gases hydrogen (H2) and methane (CH4) in the colon represents a potential explosion hazard during proctosigmoidoscopic or colonoscopic electrosurgery. In mixtures with room air, the explosive concentrations of H2 range from 4% to 74% and CH4 from 5% to 15%.' Because human flatus has been found to contain concentrations of H2 and CH4 as high as 44% and 30% respectively2, it is obvious that hazardous concentrations of both gases may be encountered during these procedures. Whi Ie we are not aware of an explosion complicating colonoscopic polypectomy, a number of serious explosions occurring during electrosurgical procedures performed through the rigid proctosigmoidoscope have been reported.''''s Both H2 and CH4 are produced in the colon by the colonic bacteria. 6 ,7 Since a relatively constant fraction of the H 2 and CH4 liberated in the colon is absorbed into the portal blood and excreted by the lungs, the production rate of these gases may be easily assessed simply by measuring their concentrations in samples of expired air. Using this method, we have previously demonstrated that while nearly everyone's colonic bacteria are capable of producing H2, only about one-third of adu Its produce appreciable quantities of CH4. 6 ,7 The following is a case report in which chromatographic breath analysis revealed the gas responsible for an explosion during sigmoidoscopic fulguration resulting in a colon perforation. "Reprint requests: Dr.

J.

H. Bond, Minneapolis VA Hospital, Minneapolis, Minnesota 55417.

VOLUME 23, NO.1, 1976

CASE REPORT A 71 year old man was referred for proctosigmoidoscopy as part of an evaluation of vague abdominal discomfort of several years' duration. The procedure was performed 2 hours after his noon meal, and he was prepared with a single sodium phosphate enema which resulted in thorough c1eansi ng of the rectosigmoid area. With the patient in the flexed prone position, the proctosigmoidoscope was easily passed to 20 cm without use of air insufflation or suction. On withdrawing the instrument, a 4 mm sessile polyp was noted at 18 cm which we elected to fulgurate using a standard blunt cautery electrode. With the cautery tip in contact with the lesion, the cautery machine was activated and there was an immediate, loud explosion. The patient's head and chest were pushed into the cushion of the examining table, and the examiner and assistant were thrown backward by the concussion. The patient felt no pain, and looking backward at the examiner who was standing with his arms raised in the air, he exclaimed, "You know, a doctor cou Id get hurt doing that!" The lumen of the sigmoidoscope was filled with black smoke and shredded tissue. When the necrotic debris was moved aside, a free perforation into the peritoneal cavity was noted. Exploratory surgery performed within 2 hours of the explosion revealed a 3 cm longitudinal perforation along the mesen· teric taenia and a split in the serosa which extended an additional 2 cm in' both directions. A small hematoma ex41

tended from the perforation into the mesentery. The surrounding colon appeared viable, there was no apparent injury to adjacent structures, and there was minimal peritoneal soilage; therefore, a primary repair of the defect was performed. The entire peritoneal cavity was lavaged with 10 liters of normal saline. The patient recovered uneventfully from surgery and left the hospital in 6 days. Breath Analysis. Within several hours of the explosion, a sample of the patient's end-expiratory air was obtained by having him exhale into a plastic tube attached with a 3-way stopcock to a 30 ml plastic syringe. Gas chromatographic analysis of this breath sample revealed a concentration of H2 of 18 ppm, and a CH4 concentration which was equal to that of room air (approximately 1.5 ppm). DISCUSSION Analysis of this patient's breath for H2 and CH4 strongly suggests that the explosion occurring in his colon was the result of electrosurgical ignition of H2 gas. In a previous study 7, healthy adults were found to consist of 2 groups on the basis of CH4 excretion: "producers" who excreted easily measurable quantities of CH4 and "nonproducers" who excreted negligible quantities (breath concentration < 1 ppm above atmospheric). Approximately onethird of the population in each decade from ages 18 to 80 are CH4 "producers" and their excretion of CH4 remains relatively constant over long periods of time. Fasting and gross alterations in diet do not appreciably influence an individual's CH4 excretion. Breath analysis indicated that our patient excreted negligible quantities of CH4 and therefore is a "nonproducer". In contrast, H2 is produced in almost everyone's colon (>95%), and the rate of production depends on the delivery to the colonic bacteria of ingested fermentable substrate primarily in the form of unabsorbed dietary carbohydrate. 6 The finding of a concentration of 18 ppm in our patient's expired air demonstrates the ability of his colonic bacteria to produce

H2o In a recent study 8, we found the colonic concentration of H2 and CH4 to be well below hazardous levels in 60 consecutive patients undergoing colonoscopy. Independent analysis of each component of the preparation procedure used for colonoscopy indicated that the ingestion of a clear liquid diet for 2 days, or fasting for 12 hours reduced H2 production to low levels, but caused only a slight fall in CH4 excretion. Thorough cleansing of the colon with cathartics and multiple enemas, which presumably removed the gas-producing organisms by physical means reduced the excretion of both gases by over 90%.

As in the present case, preparation for routine proctosigmoidoscopy rarely is as vigorous as for colonoscopy. The patient is usually not fasted, and only the rectosigmoid area is cleansed of fecal material. Thus, conditions may continue to exist which allow the production of H2 and CH4 higher in the colon, and these gases may then pass in explosive concentrations caudad into the operating field. In this situation, prevention of the rare but potentially serious complication of a colonic explosion can probably be accomplished if the area is continuously infused with an inert gas such as carbon dioxide as initially proposed by Becker. 3 The bowel injury produced by an intraluminal explosion is presumably the result of rapidly expanding gas. If the force exerted by this gas is dissipated along sufficient lengths of open colon or into the atmosphere through the endoscope, bowel injury may be slight. Pope reported a case in which a loud explosion splattered the wall with fecal material but produced no apparent injury to the patient. 4 Rapid distention ofthe colon, which may be maximal either at the operating site or more proximally where the colon is fixed or folded on itself, may produce tears just in the serosal layer or may result in full thickness perforation. Thiele described a patient who developed abdominal pain, rebound tenderness, leukocytosis, and fever without demonstrable pneumoperitoneum, uneventfully recovering without surgical exploration. 4 It seems likely that these findings may have been the result of injury only to the serosal layer. When free perforation has occurred into the peritoneal cavity, as in the present report, patients require either primary surgical closure of the defect, or, where damage is more extensive, resection of the involved bowel. 3

REFERENCES 1. LEVY EI: Explosions during lower bowel electrosurgery. Am

J Surg 88:754,

1954. 2. KIRK E: The quantity and quality of human colonic flatus.

Gastroenterology

12:782,1949. 3. BECKER GL: Prevention of gas explosions in the large bowel during elec-

trosurgery. Surg Gynecol Obstet 97:463, 1953. 4. CARTER HG: Explosion in the colon during electrodesiccation of polyps. Am

J Surg 84:514, 1952. 5. LIEBERMAN W: Inflammatory physiologic gases in the rectum and colon.

Rev

Gastroenterol 11 :259, 1944. 6. LEVITT MD: Production and excretion of hydrogen gas in man.

N Engl J Med

281 :122,1969. 7. BOND ]H, ENGEL RR, LEVITT MD: Factors influencing pulmonary methane excretion in man. J Exp Med 133:572, 1971. 8. BOND ]H, LEVITT MD: Factors affecting the concentration of combustible

gases in the colon during colonoscopy. Gastroenterology 68:1445, 1975.

An endoscopic view of mucocele of the appendix

Submucosal lesions of the colon are most often benign; they protrude into the colonic lumen and are covered by normal mucosa. Such lesions include lipomas, leiomyomas, hemangiomas, neurofibromas, and hamartomas. Malignant submucosal lesions include lymphoma and carcinoid. Mucocele of the appendix may present as a submucosal lesion with mal ignant potential. The endoscopic appearance of mucocele closely resembles that of colonic lipoma,' yet mucocele may have a much more serious prognosis. 'Reprint requests: Jeffrey L. Ponsky, MD, Department of Surgery, University Hospitals of Cleveland, 2065 Adelbert Road, Cleveland, Ohio 44106.

42

Jeffrey l. Ponsky, MD* Department of Surgery University Hospitals of Cleveland Cleveland, Ohio CASE REPORT A 65 year old white man underwent a left colectomy in 1969 for carcinoma. He did well and was followed with yearly barium enemas. He had lost no weight. In July 1974 a barium enema revealed a small polyp in the descending colon and a round, smooth, cecal lesion approximately 3 cm in diameter. His stools were guaiac negative. Colonoscopy disclosed a 3 mm sessile, inflammatory polyp in the descending colon. The cecal lesion was yellow-orange, broad-based, covered by normal mucosa, and very soft when poked with the biopsy forceps. The mucosa could be easily tented up and indented. The diagnosis was cecal lipoma, and the patient was sent home. GASTROINTESTINAL ENDOSCOPY