Supine equilibration of extracellular fluid in peritoneal dialysis varies with intra-abdominal pressure

BACKGROUND

Increased intra-abdominal pressure (PIA) leads to venous congestion in splanchnic and adjoining circulations. The aim is to examine whether PIA in peritoneal dialysis (PD) affects the mobilization of extracellular fluid from the lower body in supine body position.

METHODS

Patients were studied during a regular peritoneal equilibration test (PET) in supine body position using multifrequency bioimpedance analysis to determine extracellular resistance and absolute volume overload (AVO) in wrist-to-ankle (W2A) as well as in ankle-to-ankle (A2A) configurations. Measurements were taken at baseline (T0) after draining the peritoneal cavity, at T1 shortly after filling with 2 L of standard dialysate, and at T2 before taking the 2 h PET samples. PIA was measured from the column height in the PD catheter. Extracellular resistance in the lower extremities (RL) was taken as half of the A2A resistance.

RESULTS

Eighteen patients (56 ± 15 years, 76 ± 21 kg, body mass index (BMI) 26.4 ± 7 kg/m², 13 men) were studied. After having assumed a supine body position for the duration of 17, 77, and 155 min, AVO continuously decreased from 1.6 ± 1.3 (T0) to 1.2 ± 1.5 (T1) and 1.0 ± 1.4 L (T2). RL significantly increased from 238 ± 57 (T0) to 254 ± 62 (T1) and 264 ± 67 Ohm (T2). This increase was negatively correlated to BMI and PIA measured at any time point, but not to net ultrafiltration volume.

CONCLUSIONS

Orthostatic fluid shifts from the lower limbs may take up to 2 h in supine PD patients, especially with high BMI and PIA because of venous congestion in splanchnic and adjoining circulations.

The Occurrence of Increased Intraperitoneal Volume Events in Automated Peritoneal Dialysis in the US: Role of Programming, Patient/User Actions and Ultrafiltration

Background, objectives and methods

Increased intraperitoneal volume (IIPV) can occur during automated peritoneal dialysis (APD). The contribution of factors such as cycler programming and patient/user actions to IIPV has not been previously explored. The relationship between IIPV and cycler programming, patient/user actions, and ultra-filtration over a two-year period was investigated using US data from Baxter cyclers. Drain/fill volume ratios of > 1.6 to ≤ 2.0 and > 2.0 were defined as Level I and Level II IIPV events, respectively.

Results

Level I IIPV events occurred in 2.39% of standard and 4.73% of small fill volume therapies, while Level II IIPV events occurred in 0.26% and 1.33% of therapies, respectively. IIPV events occurred significantly more often in association with tidal peritoneal dialysis (PD) compared to non-tidal PD therapies. In tidal therapies, IIPV events were primarily related to suboptimal programming of total ultrafiltration volume. Factors that increased the odds of IIPV events during standard therapies included programming the initial drain volume target to < 70% of the last fill, and setting minimum drain volumes to < 85% of the fill volume. Bypass of initial drain by patients/users was also associated with a significant increase in the odds of IIPV events in non-tidal, but not tidal PD. An increase in the odds for IIPV was also seen for standard therapies within the highest (> 1,245 mL) versus the lowest (< 427 mL) quartile of ultrafiltration. Similar trends were seen in small fill volume therapies. Clinical presentations associated with IIPV events were not assessed.

Conclusions

IIPV events are more frequent in tidal and small fill volume therapies. The greatest potential for IIPV occurred when the total ultrafiltration was set too low for the patient's UF requirements during tidal therapy. Patient/user bypass of drains without reaching the target drain volume contributes significantly to IIPV events in non-tidal PD therapies. Poorly functioning PD catheters may be central to the cycler programming and patient/user actions that lead to IIPV.

Relationship between drain volume/fill volume ratio and clinical outcomes associated with overfill complaints in peritoneal dialysis patients

BACKGROUND

To better understand the spectrum of overfill reports and their corresponding clinical severity and etiology, we conducted a review of overfill reports from the Manufacturer and User Facility Device Experience (MAUDE) database, which is within the Food and Drug Administration (FDA) Web site (www.fda.gov).

METHOD

We searched the MAUDE database for events related to overfill reports between 1 January 1995 and 31 December 2008 and recorded drain volume (DV)/fill volume (FV), or DV/FV, and clinical symptoms and signs associated with the overfill report.

RESULTS

Among 462 MAUDE reports with a possible overfill event, 440 reports (95.2%) with a confirmed overfill event contained sufficient information to ascertain the clinical severity of the event. The number of reports with a clinical severity rating of minor, moderate, major, or death was 331, 71, 28, and 10, respectively. The median (range) DV/FV for a subgroup of 292 reports with a clinical severity rating of minor, moderate, major, or death was 1.63 (1.06 - 4.29), 1.71 (1.08 - 5.87), 2.14(1.64 - 2.61), and 2.50 (2.28 - 3.33), respectively. Insufficient drain accounted for a majority of overfill reports.

CONCLUSION

Our analysis of reports from the MAUDE database suggests an association between DV/FV and clinical severity of the reported overfill event, as well as significant patient-to-patient variability with respect to intraperitoneal volume tolerance.

Peritoneal dialysis is not associated with myocardial stunning

BACKGROUND

Hemodynamic changes during hemodialysis can precipitate subclinical myocardial ischemia, which over time contributes to the development of cardiac failure and is associated with a poor prognosis. Peritoneal dialysis (PD) is also associated with acute changes in systemic hemodynamics and a similarly high incidence of cardiovascular disease; we therefore sought to examine whether the hemodynamic effects of a PD exchange would be sufficient to induce subclinical myocardial ischemia.

METHODS

10 patients on PD entered a prospective observational study to determine whether left ventricular (LV) regional wall motion abnormalities (RWMAs) developed following a dialysate exchange. Serial echocardiography with quantitative analysis was used to assess ejection fraction and regional systolic LV function (shortening fraction). Blood pressure (BP) and hemodynamic variables were measured using continuous pulse wave analysis.

RESULTS

We observed a very low frequency of RWMA development (5/100 regions). Only 1 patient had more than 1 RWMA and 6 patients were entirely unaffected. Overall mean shortening fraction increased when comparing pre and post values for both 2-chamber (from 3.06% ± 1.5% to 4.26% ± 1.3%, p = 0.001) and 4-chamber (from 3.00% ± 0.7% to 3.67% ± 0.9%, p = 0.021) analyses. Mean arterial pressure fell by a small degree during drainage of dialysate, with a larger rise in BP observed during instillation. These changes were driven by changes in peripheral resistance that fell during drainage and rose during instillation.

CONCLUSIONS

In contrast to hemodialysis, the acute effects of PD do not result in subclinical myocardial ischemia.

Glucoregulatory hormones and choice of osmotic agent in peritoneal dialysis

OBJECTIVE

The present study was performed to explore the range of effects of amino acid-based peritoneal dialysis (PD) solutions on glucoregulatory hormones in comparison with an osmotically equivalent glucose-based solution. ♢

METHODS

13 adult nondiabetic patients on PD underwent 2 peritoneal dwells of 2 hours' duration with either 1.5% dextrose solution or 1.1% amino acid solution. Serial sampling for glucoregulatory hormones was done throughout the duration of the dwell. ♢

RESULTS

Instillation of the 1.5% dextrose solution resulted in a modest change in plasma glucose, paralleled by a small increase in plasma insulin levels and plasma insulin-like growth factor (IGF-1). Plasma glucagon was not changed and plasma growth hormone level declined. Instillation of the 1.1% amino acid solution resulted in an increase in plasma glucose, plasma insulin, plasma glucagon, and plasma IGF-1. Plasma growth hormone level declined. Both solutions led to an increase in plasma norepinephrine but no changes were observed in epinephrine or dopamine. ♢

CONCLUSIONS

Our observations suggest that the mere replacement of glucose by amino acids in PD solutions does not necessarily imply "glucose sparing" from the perspective of induction of a glucoregulatory hormonal response because of the aminogenic stimulation of secretion of multiple hormones.

Cardiac function in an African dialysis population with a low prevalence of pre-existing cardiovascular disease

Cardiac dysfunction is highly prevalent in dialysis patients in the developed world, and is a major cause of morbidity and mortality. The relative impact of pre-existing cardiac disease and dialysis/uremia on cardiovascular morbidity are not clear. We conducted a retrospective, cross-sectional analysis of cardiac function and mortality in 202 incident and prevalent dialysis patients over an 18-month period in a population with a low prevalence of cardiovascular disease at dialysis initiation. Systolic dysfunction was defined as an ejection fraction (EF) of <50%. Left ventricular hypertrophy (LVH) was determined by echocardiography or electrocardiogram. Clinical data was collected by chart review. Ninety-nine percent of patients were black, with a mean age of 41.7 +/- 10.1 years, and median follow up 28 months (range 1-216 months). Echocardiograms were available in 132 patients. Seventy-seven patients received hemodialysis, and 55 received peritoneal dialysis. Mean EF was 63.2 +/- 11.1. EF was not lower in patients with greater duration of dialysis, although LVH tended to increase (not statistically significant). In 39 patients who died during the study period, cardiac function was not different from survivors, and no patient died of ischemic heart disease or heart failure. In conclusion, in a population of patients with a low prevalence of cardiovascular disease at dialysis initiation, cardiac function appears preserved over time, and cardiac morbidity and mortality are low. This finding suggests that dialysis and uremia per se, in the absence of pre-existing cardiac disease, may not be major contributors to cardiovascular morbidity.