When Does Peritonitis Occur?

Despite the technological improvements that have occurred during the past few years, peritonitis continues to be a major complication of continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD) (I). For staff caring for patients, it frequently appears that there is a variability in the incidence ofperitonitis episodes involving the season/month of the year and the time of day. Identification and knowledge of such factors could potent ially result in interventions to decrease the peritonitis rate and may impact on staffing schedules. A Medline search was conducted as well as a review of authors' files and scanning review articles; however, no articles on circadian or seasonal variation of peritonitis were located. Seasonal variations have been reported for sperm counts and appendicitis (2,3 ), and diurnal variations have been reported for appendicitis, cholecystitis, pancreatitis, ulcers (4,5), and pneumonia susceptibility in mice (6). A total of 116 cases of peritonitis occurring over 7 years among 43 patients were retrospectively reviewed to analyze the time of day, month, and season to determine if such variations do exist. Peritonitis is defined in our center as an effluent white blood cell count of greater than 50/mm3 or clinical signs or symptoms (7). All patients with peritonitis have a detailed flow sheet initiated at the onset of signs or symptoms which includes the date and time of discovery. These data were then analyzed using the chi-square test. The months were evaluated individually and in varying groups of two and three. We reviewed the incidence of peritonitis re ated to season/month of the year with the hypothesis that seasonal differences (i.e., increased stress during the holidays, dry skin related to decreased humidity during the winter, increased perspiration, and/or increased activity during the summer) may increase the incidence of peritonitis. The data provided no monthly or seasonal prevalence ofperitonitis ( = 0.753). The time of day that peritonitis occurred was divided into hour time periods. CAPD and CCPD patients were evaluated as a combined group and separately. The interval between discovery and reporting peritonitis did not differ and was less than one hour for all cases. The 06:00,07:00,08:00,09:00, and 19:00 periods had significantly more episodes of peritonitis when compared to other times of the day (p < 0.001). Thirty-six percent of all episodes of peritonitis in the CAPD population occurred during the 06:00 10:00 time period (Table 1). Similarly, 42% of all peritonitis episodes in the CCPD patients occurred during the 06:00 10:00 time period. There was no difference in timing of peritonitis between CAPD and CCPD utilizing the Kolmogorov-Smirnov sample test (p = 0.651). There are a number of potential explanations to account for the increased incidence of peritonitis during the morning hours. One explanation for the CAPD data would be that a longer dwell or incubation period may result in an increased morning incidence. This is not supported by our CCPD data, which show the same incidence of peritonitis during the early morning and a low incidence of peritonitis after the long daytime dwell (two episodes between 18:00 and 21:59). Hence the duration of the exchange does not appear to be a major factor. A second hypothesis is that fatigue, poor lighting, and decreased concentration the night before may increase the potential for contamination at that time. Again, the CCPD data do not support this hypothesis. Another hypothesis is that abdominal pain during peritonitis is variable, subjective, and often ignored by patients during the night. This is not supported by the peak incidence of cholecystitis, appendicitis, and ulcers at 02:00 04:00 (5), which suggests that patients do recognize abdominal pain at night. In additional, the incidence is generally low throughout the day with the exceptions of the times 06:00, 07:00, 08:00, 09:00, and 19:00. Another hypothesis is that patients may not want to disturb staff for treatment or family for transportation resulting in increased early morning peritonitis. This hypothesis is difficult to evaluate, although once the staff is told or the family disturbed, there is nothing to be gained by the patient obscuring when symp toms initially occurred. Also, the experiences reported for cholecystitis, appendicitis, and ulcers would not support patients delaying their presentation. Finally, steroids are elevated during the morning hours, which may act to increase immunosuppression and potentially result in an increase in infections (8,9). Hence there are multiple potential expla nations for our observations, each with variable support.Potential considerations based on our study include the following: (1) prophylactic antibiotics (10) may need to be considered for those patients who continue to report morning episodes despite retraining and careful scrutiny of technique, and (2) staffing patterns may require alterations to accommodate the higher incidence rate during thesehours. Fur ther research to confirm our findings and elucidate an explanation is indicated.In conclusion, we found no monthly or seasonal variation in the incidence ofperitonitis.We did find a strikingly high incidence of peritonitis between 06:00 and 09:00 and at19:00 hours; the rationale for this is speculative.