EFFECT OF CATHETER DIAMETER ON RESTING PRESSURES IN ANAL-FISSURE PATIENTS

PURPOSE: Controversy exists as to whether fissure patients have elevat ed resting pressures when compared with control patients. The diameter of manometry catheters used in past studies varies widely (1.5-25 mm) and may have contributed to differences observed in resting pressures . A prospective study was undertaken to determine the influence of man ometry catheter diameter on maximum resting pressure in patients with idiopathic chronic anal fissures. METHODS: A total of 28 fissure patie nts and 28 control patients had manometry performed with both a 1.8-mm and a 4.8-mm (external diameter) water-perfused catheter. RESULTS: Me an maximum resting pressure (RP) for fissure patients as measured with the 1.8-mm catheter was 86 (range, 65-115) mmHg and 83 (range, 47-117 ) mmHg with the 4.8-mm catheter (P = 0.65). Mean maximum RP for contro l patients with the 1.8-mm catheter was 70 (range, 30-108) mmHg and 72 (range, 35-103) mmHg with the 4.8-mm catheter (P = 0.07). When fissur e and control patients were compared, a significantly higher mean RP w as observed in the fissure group for both the 1.8-mm catheter (86 vs. 70 mmHg, respectively; P = 0.01) and the 4.8-mm catheter (83 vs. 72 mm Hg, respectively, P = 0.03). There was no significant difference in le ngth of the high-pressure zone within each group or when the fissure g roup and controls were compared, regardless of catheter used. For both groups of patients, there was a significantly higher incidence of ult raslow waves (USWs) observed with the 4.8-mm catheter when compared wi th the 1.8-mm catheter. The USW frequency was not significantly differ ent when fissure and control groups were compared with either catheter type. CONCLUSIONS: Catheter size did not influence measured maximum R P in fissure patients. The maximum RP was significantly greater for fi ssure patients overall when. compared with the control group, regardle ss of catheter used. There was an increased frequency of USWs noted wi th the larger catheter size in all patients; however, these USWs only became apparent when catheter was left at each station until a true ba seline RP was obtained.