Wing-Fai Pang

Recurrent and relapsing peritonitis: causative organisms and response to treatment.

BACKGROUND The clinical behavior and optimal treatment of relapsing and recurrent peritonitis episodes in patients undergoing long-term peritoneal dialysis are poorly understood. STUDY DESIGN Retrospective study over 14 years. SETTING & PARTICIPANTS University dialysis unit; 157 relapsing episodes (same organism or culture-negative episode occurring within 4 weeks of completion of therapy for a prior episode), 125 recurrent episodes (different organism, occurs within 4 weeks of completion of therapy for a prior episode), and 764 control episodes (first peritonitis episode without relapse or recurrence). PREDICTORS Exit-site infection, empirical antibiotics. OUTCOME MEASURES Primary response (resolution of abdominal pain, clearing of dialysate, and peritoneal dialysis effluent neutrophil count < 100 cells/mL after 10 days of antibiotic therapy), complete cure (resolution by using antibiotics without relapse/recurrence), catheter removal (for any cause while on antibiotic therapy), and mortality. RESULTS Compared with the control group, more relapsing episodes were caused by Pseudomonas species (16.6% versus 9.4%) and were culture negative (29.9% versus 16.4%); recurrent infections commonly were caused by Enterococcus species (3.2% versus 1.2%) or other Gram-negative organisms (27.2% versus 11.1%) or had mixed bacterial growth (17.6% versus 12.7%). There were significant differences in primary response, complete cure, and mortality rates among groups (P < 0.001 for all comparisons). Compared with the control and relapsing groups, post hoc analysis showed that the recurrent group had a significantly lower primary response rate (86.4%, 88.5%, and 71.2%, respectively), lower complete cure rate (72.3%, 62.4%, and 42.4%, respectively), and higher mortality rate (7.7%, 7.0%, and 20.8%, respectively). LIMITATIONS Retrospective analysis. CONCLUSION Relapsing and recurrent peritonitis episodes are caused by different spectra of bacteria and probably represent 2 distinct clinical entities. Recurrent peritonitis episodes had a worse prognosis than relapsing ones.

PREDICTING 12-MONTH MORTALITY FOR PERITONEAL DIALYSIS PATIENTS USING THE "SURPRISE" QUESTION

♦ Background: Studies in hemodialysis patients suggest that the “surprise” question can help to identify a group of patients with a high mortality risk who should receive priority for palliative care interventions. However, the same instrument has not been tested in peritoneal dialysis (PD) patients. ♦ Method: We studied 367 prevalent PD patients from a single dialysis center. Three clinicians independently answered the “surprise” question (Would I be surprised if this patient died within the next 12 months?) according to their clinical impression of the individual patient. Patients are then classified into “yes” (yes, surprised) and “no” (no, not surprised) groups. All patients were followed for 12 months. ♦ Results: In this cohort, 109 patients (29.7%) were allocated to the “no” group, and 258 (70.3%), to the “yes” group. Patients in the “no” group were older and had high prevalences of pre-existing ischemic heart disease, cerebrovascular disease, and peripheral vascular disease. The “no” group had a higher score on the Charlson comorbidity index and a higher malnutrition-inflammation score. At 12 months, 44 patients had died. Mortality was 24.8% in the “no” group and 6.6% in the “yes” group. Multivariate analysis showed that an opinion of “Not surprised if dies in the next 12 months” was an independent predictor of 12-month mortality, with an associated 3.594 excess mortality risk (95% confidence interval: 1.411 to 9.151; p = 0.007). The positive predictive value of this opinion was 24.8%, and its negative predictive value was 93.4%. ♦ Conclusions: The “surprise” question has the potential to help identify a group of PD patients with high short-term mortality. Its use may contribute to a decision to refer PD patients for early palliative care assessment.

BIOIMPEDANCE SPECTROSCOPY FOR THE DETECTION OF FLUID OVERLOAD IN CHINESE PERITONEAL DIALYSIS PATIENTS

♦ Background: Fluid overload probably contributes to the cardiovascular risk of peritoneal dialysis (PD) patients. We studied the relationship between over-hydration as determined by bioimpedance spectroscopy and dialysis adequacy, nutritional status, and arterial stiffness in Chinese PD patients. ♦ Methods: We studied 122 asymptomatic prevalent PD patients: bioimpedance spectroscopy, arterial pulse wave velocity, dialysis adequacy and nutritional status were determined. ♦ Results: Of the 122 patients, 88 (72.1%) had over-hydration of ≥ 1 L, while 25 (20.5%) were ≥ 5 L. Over-hydration significantly correlated with total body water (r = 0.474, p < 0.001) and extracellular water (r = 0.755, p < 0.001). Over-hydration was more severe in male and diabetic patients, and significantly correlated with Charlson’s comorbidity score, blood pressure, body mass index, body weight, peritoneal transport characteristics, and carotid-femoral pulse wave velocity. Over-hydration significantly correlated with Kt/V (r = -0.287, p = 0.016), serum albumin level (r = -0.465, p < 0.001) and malnutrition inflammation score (r = 0.410, p = 0.006), but not residual renal function. ♦ Conclusion: Over-hydration is common in asymptomatic Chinese PD patients. The degree of over-hydration is particularly pronounced in patients who are inadequately dialyzed, have multiple comorbid conditions and low serum albumin levels. Over-hydration is associated with high blood pressure and arterial stiffness, and may contribute to the excessive risk of cardiovascular disease in this group of patients.

Repeat Peritonitis in Peritoneal Dialysis: Retrospective Review of 181 Consecutive Cases

BACKGROUND AND OBJECTIVES The clinical behavior of repeat-peritonitis episodes, defined as peritonitis with the same organism occurring more than 4 weeks after completion of therapy for a prior episode, is poorly understood. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We compared outcomes of 181 episodes of repeat peritonitis from 1995 to 2009 (Repeat Group) with 91 episodes of relapsing peritonitis (Relapsing Group) and 125 episodes of peritonitis preceded 4 weeks or longer by another episode with a different organism (Control Group). RESULTS In Repeat Group, 24% were due to Staphylococcus aureus, as compared with 5.5% in Relapsing Group and 15% in Control Group. The majority of the organisms causing relapsing peritonitis were Gram negative (62%), whereas the majority of that in Repeat Group were Gram positive (56%). Repeat Group had a lower complete-cure rate (70.7% versus 54.9%) than Relapsing Group, but rates of primary response, catheter removal, and mortality were similar. Repeat Group had a higher primary response rate (89.0% versus 73.6%) and a lower rate of catheter removal (6.1% versus 15.2%) than Control Group, whereas the complete-cure rate and mortality were similar. Repeat Group had a higher risk of developing relapsing (14.3% versus 2.2%) and repeat peritonitis (26.1% versus 5.4%) than Control Group, whereas the risk of recurrent peritonitis was similar. CONCLUSIONS Repeat peritonitis is a distinct clinical entity. Although repeat-peritonitis episodes generally have a satisfactory response to antibiotic, they have a substantial risk of developing further relapsing or repeat peritonitis.

Endotoxemia is Associated with Better Clinical Outcome in Incident Chinese Peritoneal Dialysis Patients: A Prospective Cohort Study

♦ Background: Endotoxemia is common in peritoneal dialysis (PD) patients; circulating lipopolysaccharide (LPS) level is related to the degree of systemic inflammation and atherosclerosis. We examine whether baseline plasma LPS level represents a prognostic marker in new PD patients. ♦ Methods: We studied 158 new Chinese PD patients (80 males). Baseline plasma LPS level at initiation of PD was measured. Patients were stratified into quartiles according to plasma LPS level: quartile I, <0.45 EU/mL; II, 0.45 – <0.70 EU/mL; III, 0.70 – <0.95 EU/mL; and IV, ≥0.95 EU/mL. The patients were then prospectively followed for the development of cardiovascular events. All-cause mortality and duration of hospitalization were also recorded. ♦ Results: Average age was 55.6 ± 14.7 years; average endotoxin concentration was 0.70 ± 0.30 EU/mL; average follow-up was 55.5 ± 36.9 months. At 60 months, event-free survival was 41.0%, 52.5%, 65.0%, and 61.5% for LPS level quartiles I, II, III, and IV, respectively (log rank test p = 0.066). By multivariate analysis with the Cox proportional hazard model to adjust for confounders, plasma LPS level had no independent effect. At 60 months, technique survival was 20.5%, 20.0%, 32.5%, and 51.3% for LPS level quartiles I, II, III, and IV, respectively (log rank test p = 0.0009). By Cox proportional hazard model, each higher quartile of LPS conferred 28.6% protection (95% confidence interval 15.6% – 40.3%, p = 0.0002) from developing technique failure. A higher plasma LPS level had a lower all-cause mortality (unadjusted hazard ratio 0.486, p = 0.046) and cardiovascular mortality (unadjusted hazard ratio 0.251, p = 0.025), but the result became insignificant after adjusting for potential confounders. ♦ Conclusion: A higher baseline plasma LPS level is an independent predictor of better technique survival in new Chinese PD patients, with an insignificant trend of fewer cardiovascular events. The observation seems to conform to the phenomenon of reverse epidemiology for other traditional cardiovascular risk factors in dialysis patients but the exact reason for this paradoxical phenomenon requires further investigation.

Circulating bacterial-derived DNA fragment level is a strong predictor of cardiovascular disease in peritoneal dialysis patients.

Background Circulating bacterial DNA fragment is related to systemic inflammatory state in peritoneal dialysis (PD) patients. We hypothesize that plasma bacterial DNA level predicts cardiovascular events in new PD patients. Methods We measured plasma bacterial DNA level in 191 new PD patients, who were then followed for at least a year for the development of cardiovascular event, hospitalization, and patient survival. Results The average age was 59.3 ± 11.8 years; plasma bacterial DNA level 34.9 ± 1.5 cycles; average follow up 23.2 ± 9.7 months. At 24 months, the event-free survival was 86.1%, 69.8%, 55.4% and 30.8% for plasma bacterial DNA level quartiles I, II, III and IV, respectively (p < 0.0001). After adjusting for confounders, plasma bacterial DNA level, baseline residual renal function and malnutrition-inflammation score were independent predictors of composite cardiovascular end-point; each doubling in plasma bacterial DNA level confers a 26.9% (95% confidence interval, 13.0 – 42.5%) excess in risk. Plasma bacterial DNA also correlated with the number of hospital admission (r = -0.379, p < 0.0001) and duration of hospitalization for cardiovascular reasons (r = -0.386, p < 0.0001). Plasma bacterial DNA level did not correlate with baseline arterial pulse wave velocity (PWV), but with the change in carotid-radial PWV in one year (r = -0.238, p = 0.005). Conclusions Circulating bacterial DNA fragment level is a strong predictor of cardiovascular event, need of hospitalization, as well as the progressive change in arterial stiffness in new PD patients.

Remote ischaemic pre‐conditioning for the prevention of acute kidney injury

Acute kidney injury (AKI) is a common complication associated with high morbidity and mortality in hospitalized patients. One potential mechanism underlying renal injury is ischaemia/reperfusion injury (IRI), which attributed the organ damage to the inflammatory and oxidative stress responses induced by a period of renal ischaemia and subsequent reperfusion. Therapeutic strategies that aim at minimizing the effect of IRI on the kidneys may prevent AKI and improve clinical outcomes significantly. In this review, we examine the technique of remote ischaemic preconditioning (rIPC), which has been shown by several trials to confer organ protection by applying transient, brief episodes of ischaemia at a distant site before a larger ischaemic insult. We provide an overview of the current clinical evidence regarding the renoprotective effect of rIPC in the key clinical settings of cardiac or vascular surgery, contrast‐induced AKI, pre‐existing chronic kidney disease (CKD) and renal transplantation, and discuss key areas for future research.

PERSISTENT SYMPTOMATIC INTRA-ABDOMINAL COLLECTION AFTER CATHETER REMOVAL FOR PD-RELATED PERITONITIS

♦ Background: Peritoneal dialysis (PD) patients with severe peritonitis require catheter removal. It is often assumed that this approach, together with antibiotics, would eradicate the infection; however, some patients continue to have problems despite catheter removal. ♦ Method: We reviewed 30 consecutive PD patients in our center from 1997 to 2008 with recurrent loculated peritoneal collection after catheter removal for severe peritonitis. ♦ Results: Of the 1928 episodes of peritonitis that occurred in 702 patients during the study period, 11.1% required catheter removal and 1.6% developed recurrent peritoneal collection that required percutaneous drainage. Median time to diagnosis of intra-abdominal collection was 12 days after catheter removal (interquartile range 7 – 61 days). In 25 patients (83.3%), aspirate of the abdominal collection was culture negative. In 17 patients (56.7%), the abdominal collection was recurrent and required repeated percutaneous aspiration. Only 3 patients had successful reinsertion of the peritoneal catheter but all had reduced small solute clearance after returning to PD. ♦ Conclusion: A small but not negligible proportion of patients with PD-related peritonitis develop recurrent intra-abdominal collection that requires percutaneous drainage after catheter removal. The chance of a successful return to PD is very low in this group of patients. Direct conversion to long-term hemodialysis may avoid unnecessary attempts at peritoneal catheter reinsertion.

ARTERIAL PULSE WAVE VELOCITY AND PERITONEAL TRANSPORT CHARACTERISTICS INDEPENDENTLY PREDICT HOSPITALIZATION IN CHINESE PERITONEAL DIALYSIS PATIENTS

♦ Objective: Cardiovascular disease (CVD) is the most common cause of mortality in chronic peritoneal dialysis (PD) patients. Increased arterial stiffness may be related to a high peritoneal permeability resulting in fluid overload in PD patients. We studied the relations between arterial stiffness, peritoneal transport, and radiographic parameters of systemic fluid overload in a cohort of Chinese PD patients. ♦ Design: Prospective cohort study. ♦ Setting: University referral center. ♦ Patients: We studied 107 PD patients. Vascular pedicle width and cardiothoracic ratio were measured from a plain postero-anterior chest radiograph. Pulse wave velocity (PWV) was determined at carotid–femoral (C-F) and carotid–radial sites. Peritoneal transport was determined by the dialysate-to-plasma ratio (D/P) of creatinine at 4 hours of dwell. Patients were followed for 9.4 ± 4.6 months. ♦ Outcome Measures: Duration of hospitalization; actuarial and technique survival. ♦ Results: There were no relationships between radiographic measures, arterial PWV, and D/P creatinine. However, both C-F PWV and D/P creatinine were independent predictors of the number of hospitalizations for CVD. None of the parameters correlated with mortality in this study. ♦ Conclusions: There were no relationships between radiological parameters of fluid overload, peritoneal transport characteristics, and arterial PWV. Both C-F PWV and D/P creatinine were independent predictors of the number of hospitalizations for CVD. Our result suggests that arterial stiffness and high peritoneal transport each contribute to the development of CVD in this group of patients.

Outcome of Hemodialysis Patients Who Had Failed Peritoneal Dialysis

Background: Peritoneal dialysis (PD) and hemodialysis (HD) are often regarded as equivalent choices of renal replacement therapy. However, little is known about the outcome of patients who failed PD and converted to long-term HD. Methods: We reviewed 197 patients who received long-term HD after failed PD in a University hospital from 1994 to 2008 (the PD-first group) and 140 patients who received long-term HD as their initial therapy during that period (the primary-HD group). Their survival rates are compared. Results: The two groups are highly comparable in terms of baseline demographic data. The PD-first group required more temporary dialysis catheters than the primary-HD group (3.1 ± 3.4 vs. 1.5 ± 1.8, p < 0.0001). At 5 years, the actuarial survival of the PD-first group was significantly lower than that of the primary-HD group (39.9 vs. 59.7%, p < 0.0001), while technique survival was similar (30.4 vs. 30.1%, p = 0.7). When analysis on actuarial survival was performed for patients who survived the first 12 months on HD, the 5-year survival became similar (65.2 vs. 68.8%, p = 0.5). During the first 12 months on HD, independent predictors of actuarial survival of the PD-first group were duration of PD, Charlson’s comorbidity score, type of permanent access and serum albumin before conversion; after 12 months, independent predictors of actuarial survival were Charlson’s comorbidity score, total Kt/V, residual renal function, fat-free edema-free body mass before conversion and baseline peritoneal transport. Conclusion: Patients who were converted to long-term HD after failed PD had a higher mortality than patients who used HD as the primary modality of renal replacement therapy. The excessive mortality, however, was limited to the first 12 months after conversion, and the technique survival was similar between the two groups. Vascular access is a common problem in patients who failed PD.