Prevalence of intradialytic hypotension, clinical symptoms and nursing interventions--a three-months, prospective study of 3818 haemodialysis sessions.

BACKGROUND: Intradialytic hypotension (IDH) is considered one of the most frequent complications of haemodialysis with an estimated prevalence of 20-50 %, but studies investigating its exact prevalence are scarce. A complicating factor is that several definitions of IDH are used. The goal of this study was, to assess the prevalence of IDH, primarily in reference to the European Best Practice Guideline (EBPG) on haemodynamic instability: A decrease in systolic blood pressure (SBP) ≥20 mmHg or in mean arterial pressure (MAP) ≥10 mmHg associated with a clinical event and the need for nursing intervention. METHODS: During 3 months we prospectively collected haemodynamic data, clinical events, and nursing interventions of 3818 haemodialysis sessions from 124 prevalent patients who dialyzed with constant ultrafiltration rate and dialysate conductivity. Patients were considered as having frequent IDH if it occurred in >20 % of dialysis sessions. RESULTS: Decreases in SBP ≥20 mmHg or MAP ≥10 mmHg occurred in 77.7 %, clinical symptoms occurred in 21.4 %, and nursing interventions were performed in 8.5 % of dialysis sessions. Dialysis hypotension according to the full EBPG definition occurred in only 6.7 % of dialysis sessions. Eight percent of patients had frequent IDH. CONCLUSIONS: The prevalence of IDH according to the EBPG definition is low. The dominant determinant of the EBPG definition was nursing intervention since this was the component with the lowest prevalence. IDH seems to be less common than indicated in the literature but a proper comparison with previous studies is complicated by the lack of a uniform definition.

Variability of predialytic, intradialytic, and postdialytic blood pressures in the course of a week: a study of Dutch and US maintenance hemodialysis patients.

BACKGROUND: Patients with thrice-weekly hemodialysis have higher predialysis weights and ultrafiltration rates at the first compared with subsequent dialysis sessions of the week. We hypothesized that these variations in weight and ultrafiltration rate are associated with a systematic difference in blood pressure. STUDY DESIGN: Observational study. SETTING & PARTICIPANTS: During 3 months, we prospectively collected hemodynamic data for 4,007 hemodialysis sessions involving 124 Dutch patients. A similar analysis was performed with 789 US patients, comprising 6,060 hemodialysis sessions. FACTOR: First versus subsequent hemodialysis sessions of the week. OUTCOMES: Blood pressure. MEASUREMENTS: Blood pressure, weight, and ultrafiltration rate were analyzed separately for the first, second, and third dialysis sessions of the week. Comparisons were made with linear mixed models. RESULTS: In Dutch patients, predialysis weight and ultrafiltration rate were significantly greater at the first compared with subsequent hemodialysis sessions of the week (P < 0.001). Predialysis systolic and diastolic blood pressures were higher at the first than at subsequent sessions of the week (P < 0.001). Predialysis blood pressure differences persisted throughout the session: systolic and diastolic blood pressures were on average 5.0 and 2.5 mm Hg higher during the first compared to the third session of the week. Postdialysis blood pressures followed a similar pattern (P < 0.001). Blood pressure differences between the first and subsequent days of the week persisted after adjustment for possible confounders. Results in the US cohort were materially identical despite differences in patient characteristics and treatment practice between the 2 cohorts. LIMITATIONS: Dry weight was not assessed by objective methods. CONCLUSIONS: Blood pressure of patients on a thrice-weekly dialysis schedule varies systematically over the week. Predialysis blood pressure is highest at the first hemodialysis session of the week, most likely due to greater interdialytic weight gain. Intra- and postdialytic blood pressures also are highest at the first session of the week despite higher ultrafiltration rates.

Comparison of cardiac positron emission tomography perfusion defects during stress induced by hemodialysis versus adenosine.

The cardiac stress imposed by hemodialysis may differ from that induced by pharmacologic agents used for myocardial perfusion imaging-based stress testing. With repetitive intradialytic [(13)N]ammonia positron emission tomography, we showed that standard hemodialysis had an acute adverse effect on cardiac perfusion and left ventricular function that was not detected by standard diagnostic adenosine stress testing.

Critical evaluation of blood volume measurements during hemodialysis.

Devices that continuously measure relative blood volume (RBV) changes during hemodialysis (HD) are increasingly used for the prevention of dialysis hypotension and fine-tuning of dry weight. However, RBV measurements are subject to various limitations. First, RBV devices provide information on relative blood volume changes but not on absolute blood volume. Since blood volume varies with the hydration status, identical reductions of RBV may result in very different absolute blood volumes at the end of HD. Second, RBV changes underestimate the change of total blood volume due to translocation of lower-hematocrit blood from the microcirculation to the central circulation. Third, changes in posture before and during HD, food intake, exercise, and administration of intravenous fluids may influence the validity of the RBV measurement. Fourth, results obtained by various RBV devices show large interdevice differences. Finally, although a fall in blood volume is an important factor in dialysis hypotension, frank dialysis hypotension only occurs when the cardiovascular compensatory mechanisms can no longer compensate for the reduction in blood volume. Therefore, the dialysis staff should not exclusively focus on RBV, but also search for opportunities in the dialysis prescription to facilitate cardiovascular compensatory mechanisms, e.g. by lowering dialysate temperature. In the opinion of the authors, routine RBV monitoring should be used with caution until the major conceptual and methodological problems that are inherent to the indirect RBV estimation are clarified.

Cone-beam computed tomography-guided online adaptive radiotherapy is feasible for prostate cancer patients.

Background and purpose: Studies have shown the potential of cone-beam computed tomography (CBCT)-guided online adaptive radiotherapy (oART) for prostate cancer patients in a simulation environment. The aim of this study was to evaluate the feasibility of the clinical implementation of CBCT-guided oART for prostate cancer patients. Materials and methods: Between February and July 2020, eleven prostate cancer patients were treated with CBCT-guided oART using a fractionation scheme of 20 × 3 Gy to the prostate and 20 × 2.7/3.0 Gy to the seminal vesicles for more advanced stages. The on-couch adaptive workflow consisted of influencer (prostate, seminal vesicles, rectum, bladder) review, target review, scheduled (re-calculated) and adapted (re-optimized) plan generation, an independent QA procedure and treatment delivery. Treatment time, proportion of adapted fractions and reasons for plan adaptation were evaluated. Results: Mean total treatment time (±SD) from CBCT acquisition to end of treatment delivery was 17.5 ±â€¯3.2 min (range: 10.8-28.8 min). In all 220 fractions, the PTV coverage was increased for the adapted plan compared to the scheduled plan. The V60Gy of bladder and rectum were below the constraints (<5% and <3%) for both scheduled and adapted plans in 171 out of 220 fractions and for the adapted plan only in 30 out of 220 fractions. In 19 out of 220 fractions, the V60Gy of the bladder and/or rectum was above the constraint for the adapted plan. Conclusions: The clinical implementation of CBCT-guided oART is feasible for prostate cancer patients. The adaptive workflow is possible within twenty minutes on average with a dedicated team.

Haemodialysis is associated with a pronounced fall in myocardial perfusion.

BACKGROUND: Whereas haemodialysis (HD) is lifesaving by replacement of renal function, there are data to suggest that the HD procedure itself may contribute to the high cardiac risk in dialysis patients. The HD procedure is associated with an increased risk of sudden death, and there is accumulating evidence that HD can elicit myocardial ischaemia. In this study, we evaluated the effect of HD on global and regional myocardial blood flow (MBF) and left ventricular (LV) function in non-diabetic, non-cardiac compromised patients. METHODS: (13)N-NH(3) positron emission tomography (PET) was used to quantify changes in MBF, LV wall motion, cardiac output (CO), LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) in seven non-diabetic patients with uneventful cardiac histories. PET scans were performed before and at 30 and 220 min of HD. RESULTS: In all patients global MBF fell during HD. At 30 min of HD without ultrafiltration (UF), global MBF had fallen 13.5 +/- 11.5% (P < 0.05) while CO, LVEDV and LVESV were 4.6 +/- 5.3% (NS), 5.6 +/- 4.2% (P < 0.05) and 6.9 +/- 7.2% (P < 0.05) lower, respectively. At 220 min of HD, after UF of 2.5 +/- 0.9 l, global MBF had fallen 26.6 +/- 13.9% (P < 0.05) from baseline while CO, LVEDV and LVESV were 21.0 +/- 19.7%, 31.1 +/- 12.7% and 36.4 +/- 17.5% (all P < 0.05) lower, respectively. In two patients, new LV regional wall motion abnormalities (RWMA) developed at 220 min of HD. MBF was reduced to a greater extent in regions that developed LV RWMA compared to those that did not. CONCLUSIONS: Haemodialysis induced a pronounced fall in MBF. Since MBF fell already early during HD not only hypovolaemia but also acute dialysis-associated factors seem to play a role. Haemodialysis-associated reductions in MBF may contribute to the high cardiac event rate of dialysis patients.

Relative blood volume measurements during hemodialysis: comparisons between three noninvasive devices.

The monitoring of relative blood volume changes (DeltaRBV) has been advocated for the prevention of hemodialysis (HD) hypotension. Stand-alone devices (Crit-Line) or devices incorporated into the HD apparatus (blood volume monitor [BVM], Hemoscan) are widely used for this purpose. Comparisons between devices are scarce. The aim of this study was, first, to compare DeltaRBV results from these 3 devices with DeltaRBV calculated from changes in laboratory-derived hemoglobin (DeltaRBV-lab-Hb) and, second, to compare DeltaRBV results between the different devices. Fourteen patients received 2 HD treatments in a randomized order: one with the Hemoscan and Crit-Line combination and one with the BVM and Crit-Line combination. DeltaRBV-lab-Hb was measured at 2 and 4 hr into the HD session. Bland-Altman analyses showed that DeltaRBV results from the 3 devices differed systematically from DeltaRBV-lab-Hb, i.e., the difference between the 3 devices and DeltaRBV-lab-Hb varied significantly (p<0.05) with the magnitude of the measurement. The interdevice comparison showed considerable differences in DeltaRBV results. At the end of the treatment, a significant difference (p<0.05) between DeltaRBV measured by the Hemoscan and Crit-Line device (-9.8+/-2.7% and -11.5+/-4%, respectively) was found. In most patients, a systematic difference between Crit-Line and Hemoscan and between Crit-Line and BVM was observed. Relative blood volume change measurements by Crit-Line, Hemoscan, and BVM yield results that differ systematically from the results obtained from laboratory-derived Hb changes. Furthermore, there are substantial differences in DeltaRBV results between the 3 DeltaRBV devices.

Effect of high and low ultrafiltration volume during hemodialysis on relative blood volume.

Achieving an optimal post-hemodialysis hydration status may be difficult because objective criteria for dry weight are lacking. Both relative blood volume changes (DeltaRBV) at the end of hemodialysis and DeltaRBV normalized for ultrafiltration volume (DeltaRBV/UF ratio) have been reported to indicate post-hemodialysis volume status. A parameter for volume status should not be influenced by variations in ultrafiltration volume. However, if the volume that has to be ultrafiltrated to reach dry weight varies as a result of variations in pre-hemodialysis weight, either DeltaRBV or the DeltaRBV/UF ratio (or both) must change. To elucidate the relation between intradialytic ultrafiltration volume versus DeltaRBV and its derivative, the DeltaRBV/UF ratio, we studied the effect of a relatively high (mean+/- SD, 2.7+/- 0.5 l) and low (1.5+/- 0.3 l) intradialytic ultrafiltration volume on these parameters in eight patients. Post-hemodialysis weight was comparable in low and high ultrafiltration volume sessions. The average end-hemodialysis DeltaRBV did not differ between high (-6.7+/- 2.5%) and low ultrafiltration volume sessions (-7.3+/- 1.0%; NS), but the intraindividual variation was considerable. The DeltaRBV/UF ratio differed markedly (p<0.001) between high (-2.4+/- 0.8 %/l) and low (-4.9+/- 1.3 %/l) ultrafiltration volume sessions. In conclusion, the considerable random intraindividual variation of DeltaRBV and the systematic change of the DeltaRBV/UF ratio with variations in intradialytic ultrafiltration volume limit the use of these parameters as an aid to assess hydration status in hemodialysis patients.

Automatic feedback control of relative blood volume changes during hemodialysis improves blood pressure stability during and after dialysis.

Automatic feedback systems have been designed to control relative blood volume changes during hemodialysis (HD) as hypovolemia plays a major role in the development of dialysis hypotension. Of these systems, one is based on the concept of blood volume tracking (BVT). BVT has been shown to improve intra-HD hemodynamic stability. We first questioned whether BVT also improves post-HD blood pressure stability in hypotension-prone patients and second, whether BVT is effective in reducing the post-HD weight as many hypotension-prone patients are overhydrated because of an inability to reach dry weight. After a 3-week period on standard HD, 12 hypotension-prone patients were treated with two consecutive BVT treatment protocols. During the first BVT period of 3 weeks, the post-HD target weight was kept identical compared with the standard HD period (BVT-constant weight; BVT-cw). During the second BVT period of 6 weeks, we gradually tried to lower the post-HD target weight (BVT-reduced weight; BVT-rw). In the last week of each period, we studied intra-HD and 24 hr post-HD blood pressure behavior by ambulatory blood pressure measurement (ABPM). Pre- and post-HD weight did not differ between standard HD and either BVT-cw or BVT-rw. Heart size on a standing pre-dialysis chest X-ray did not change significantly throughout the study. There were less episodes of dialysis hypotension during BVT compared with standard HD (both BVT periods: p<0.01). ABPM data were complete in 10 patients. During the first 16 hr post-HD, systolic blood pressure was significantly higher with BVT in comparison with standard HD (both BVT periods: p<0.05). The use of BVT in hypotension-prone patients is associated with higher systolic blood pressures for as long as 16 hr post-HD. BVT was not effective in reducing the post-HD target weight in this patient group.

Influence of ultrafiltration volume on blood volume changes during hemodialysis as observed in day-of-the-week analysis of hemodialysis sessions.

Monitoring of relative blood volume changes (DeltaRBV) has been propagated for the prevention of hemodialysis hypotension. Although the influence of ultrafiltration volume on DeltaRBV is well-known, there is no mention in the literature that DeltaRBV results should be interpreted differently for the first, second, or third hemodialysis session of the week. To elucidate whether DeltaRBV and its derivative, DeltaRBV normalized for ultrafiltration volume (DeltaRBV/ultrafiltration ratio), vary systematically over the week, we separately analyzed these parameters for the first, second, and third hemodialysis session of the week in 13 chronic hemodialysis patients over a 17-week period. As expected, mean (+/-SD) ultrafiltration volume was significantly (p < 0.001) higher during the first session than during the second and third hemodialysis sessions (3163 +/- 615, 2622 +/- 674 and 2607 +/- 638 ml, respectively). DeltaRBV was significantly (p < 0.01) more negative at the first session than at the second and third hemodialysis sessions (-10.1 +/- 2.7, -9.3 +/- 3.0 and -9.3 +/- 3.1%, respectively). The DeltaRBV/ultrafiltration ratio was significantly (p < 0.01) less negative at the first session than at the second and third hemodialysis sessions (-3.2 +/- 0.6, -3.5 +/- 0.8 and -3.6 +/- 0.6%/l, respectively). In conclusion, DeltaRBV and the DeltaRBV/ultrafiltration ratio differ systematically between the first and other hemodialysis sessions in patients on a thrice-weekly hemodialysis schedule, most likely as a result of different ultrafiltration volumes.

Effects of relative blood volume-controlled hemodialysis on blood pressure and volume status in hypertensive patients.

In hypertensive hemodialysis (HD) patients, dry weight reduction to normalize blood pressure (BP) often results in increased frequency of HD hypotension. Because HD with blood volume tracking (BVT) has been shown to improve intra-HD hemodynamic stability, we performed a prospective, randomized study to test whether BVT is more effective than standard hemodialysis (SHD) in the management of hypertension by dry weight reduction. After a run-in period of 4 weeks on SHD, 28 patients were randomly assigned for a 12-week treatment period with either SHD (n = 14) or BVT (n = 14). The mean pre-HD and post-HD weight did not change over time in either group. In the BVT group, pre-HD systolic and diastolic BP decreased on average 22.5 mm Hg and 8.3 mm Hg, respectively (both p < 0.05), whereas BP did not change in the SHD group. Extracellular water and cardiothoracic ratio decreased significantly (all p < 0.05) in the BVT group but not in the SHD group. Brain natriuretic peptide levels declined only in the BVT group, without reaching statistical significance. The frequency of HD hypotensive episodes decreased significantly (p < 0.05) in the BVT group and was unchanged in the SHD group. HD with BVT was associated with a significant reduction in pre-HD BP. At the same time, the frequency of intra-HD hypotensive episodes decreased. Although the mean weight did not change, the reductions in cardiothoracic ratio and extracellular water suggest that HD with BVT resulted in optimization of volume status.

Relative blood volume changes underestimate total blood volume changes during hemodialysis.

BACKGROUND: Measurements of relative blood volume changes (DeltaRBV) during hemodialysis (HD) are based on hemoconcentration and assume uniform mixing of erythrocytes and plasma throughout the circulation. However, whole-body hematocrit (Ht) is lower than systemic Ht. During HD, a change in the ratio between whole-body to systemic Ht (F cell ratio) is likely to occur as a result of a net shift of low Ht blood from the microcirculation to the macrocirculation. Hence, DeltaRBV may differ significantly from total blood volume changes (DeltaTBV). Therefore, this study compared DeltaRBV and DeltaTBV during HD. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: Plasma and erythrocyte volumes were measured using (125)I- and (123)I-radioiodinated albumin and (51)Cr-labeled erythrocytes, respectively. After validation of the standardized method in two patients on a nondialysis day, seven patients completed the protocol during HD. (125)I-albumin and (51)Cr-labeled erythrocytes were administered 20 min before the start of HD. (123)I-albumin was administered at 160 min into the HD session to quantify and correct for (125)I-albumin leakage. DeltaRBV was measured continuously throughout HD. The F cell ratio was derived from whole-body and systemic Ht. RESULTS: Total ultrafiltration volume was 2450 +/- 770 ml. TBV declined from 5905 +/- 824 to 4877 +/- 722 ml during HD. Thus, TBV declined 17.3 +/- 4.4%, whereas the RBV decline was only 8.2 +/- 3.7% (P = 0.001). The F cell ratio increased from 0.896 +/- 0.036 to 0.993 +/- 0.049 during HD (P = 0.002). CONCLUSIONS: DeltaRBV significantly underestimates DeltaTBV during HD. The rise in F cell ratio strongly suggests that during HD, blood translocates from the microcirculation to the macrocirculation, probably as a cardiovascular compensatory mechanism in response to hypovolemia.