Predictors of haemodynamic instability and heart rate variability during haemodialysis.

BACKGROUND: The pathogenesis of haemodialysis-induced hypotension is multifactorial and may include autonomic nervous system dysfunction. The present study was undertaken to (i) determine heart rate variability (HRV) in chronic haemodialysis patients without and with haemodynamic instability (hypotension-prone) during ultrafiltration and (ii) identify patients at risk and the predictors of dialysis-related hypotension. METHODS: HRV was evaluated in 56 chronic haemodialysis patients without (stable; n = 27) and with symptomatic hypotension episodes (unstable; n = 29) during daytime, haemodialysis and night-time periods. Logistic regression analysis was performed in a model that included clinical and biochemical data and HRV measurements. RESULTS: HRV was significantly reduced in haemodynamically unstable as compared with the stable patients. LF/HF ratio, an index representative of sympathovagal balance, was significantly lower in unstable patients, especially in those with ischaemic heart disease and diabetes mellitus. In a logistic regression model including clinical data and HRV measurements, ischaemic heart disease and left ventricular systolic dysfunction were found to be the main predictors of haemodynamic instability. CONCLUSIONS: These data suggest that haemodynamic instability is strongly associated with a decreased HRV and an impaired sympathovagal balance, suggesting disturbed autonomic control in uraemic patients with cardiac damage. Patients with ischaemic heart disease, reduced left ventricular systolic function and decreased HRV may be at the highest risk to be haemodynamically unstable during haemodialysis. The role of early detection and treatment of ischaemic heart disease in preventing symptomatic hypotensive episodes in these patients remains to be determined.     

The faster potassium-lowering effect of high dialysate bicarbonate concentrations in chronic haemodialysis patients.

BACKGROUND: Hyperkalaemia is common in patients with advanced renal disease. In this double-blind, randomized, three-sequence, crossover study, we compared the effect of three dialysate bicarbonate concentrations ([HCO3-]) on the kinetics of serum potassium (K+) reduction during a conventional haemodialysis (HD) session in chronic HD patients. METHODS: We studied eight stable HD patients. The choice of dialysate [HCO3-] followed a previously assigned treatment protocol and the [HCO3-] used were low bicarbonate (LB; 27 mmol/l), standard bicarbonate (SB; 35 mmol/l) and high bicarbonate (HB; 39 mmol/l). Polysulphone dialysers and automated machines provided blood flow rates of 300 ml/min and dialysis flow rates of 500 ml/min for each HD session. Blood samples were drawn at 0 (baseline), 15, 30, 60 and 240 min from the arterial extracorporeal line to assess blood gases and serum electrolytes. In three of the eight patients, we measured serum K+ 1 h post-dialysis as well as K+ removal by the dialysis. The same procedures were followed until the completion of the three arms of the study, with a 1 week interval between each experimental arm. RESULTS: Serum K+ decreased from 5.4+/-0.26 (baseline) to 4.96+/-0.20, 4.90+/-0.19, 4.68+/-0.13 and 4.24+/-0.15 mmol/l at 15, 30, 60 and 240 min, respectively, with LB; from 5.38+/-0.21 to 5.01+/-0.23, 4.70+/-0.25, 4.3+/-0.15 and 3.8+/-0.19 mmol/l, respectively, with SB; and from 5.45+/-0.25 to 4.79+/-0.17, 4.48+/-0.17, 3.86+/-0.16 and 3.34+/-0.11 mmol/l, respectively, with HB (P<0.05 for high vs standard and low [HCO3-] at 60 and 240 min). The decrease in serum K+ correlated with the rise in serum [HCO3-] in all but LB (P<0.05). Potassium rebound was 3.9+/-10.2%, 5.2+/-6.6% and 8.9+/-4.9% for LB, SB and HB dialysates, respectively (P=NS), while total K+ removal (mmol/dialysis) was 116.4+/-21.6 for LB, 73.2+/-12.8 for SB and 80.9+/-15.4 for HB (P=NS). CONCLUSIONS: High dialysate [HCO3-] was associated with a faster decrease in serum K+. Our results strongly suggest that this reduction was due to the enhanced shifting of K+ from the extracellular to the intracellular fluid compartment rather than its removal by dialysis. This finding could have an impact for those patients with life-threatening pre-HD hyperkalaemia.     

Variability of relative blood volume during haemodialysis.

BACKGROUND: A decrease in blood volume is thought to play a role in dialysis-related hypotension. Changes in relative blood volume (RBV) can be assessed by means of continuous haematocrit measurement. We studied the variability of RBV changes, and the relation between RBV and ultrafiltration volume (UV), blood pressure, heart rate, and inferior caval vein (ICV) diameter. METHODS: In 10 patients on chronic haemodialysis, RBV measurement was performed during a total of one hundred 4-h haemodialysis sessions. Blood pressure and heart rate were measured at 5-min intervals. ICV diameter was assessed at the start and at the end of dialysis using ultrasonography. RESULTS: The changes in RBV showed considerable inter-individual variability. The average change in RBV ranged from -0.5 to -8.2% at 60 min and from -3.7 to -14.5% at 240 min (coefficient of variation (CV) 0.66 and 0.35 respectively). Intra-individual variability was also high (CV at 60 min 0.93; CV at 240 min 0.33). Inter-individual as well as intra-individual variability showed only minor improvement when RBV was corrected for UV. We found a significant correlation between RBV and UV at 60 (r= -0.69; P<0.001) and at 240 min (r= -0.63; P<0.001). There was a significant correlation between RBV and heart rate (r= -0.39; P<0.001), but not between RBV or UV and blood pressure. The level of RBV reduction at which hypotension occurred was also highly variable. ICV diameter decreased from 10.3+/-1.7 mm/m(2) to 7.3+/-1. 5 mm/m(2). There was only a slight, although significant, correlation between ICV diameter and RBV (r= -0.23; P<0.05). The change in ICV-diameter showed a wide variation. CONCLUSIONS: RBV changes during haemodialysis showed a considerable intra- and inter-individual variability that could not be explained by differences in UV. No correlation was observed between UV or changes in RBV and either blood pressure or the incidence of hypotension. Heart rate, however, was significantly correlated with RBV. Moreover, IVC diameter was only poorly correlated with RBV, suggesting a redistribution of blood towards the central venous compartment. These data indicate that RBV monitoring is of limited use in the prevention of dialysis-related hypotension, and that the critical level of reduction in RBV at which hypotension occurs depends on cardiovascular defence mechanisms such as sympathetic drive.     

Acute hypernatraemia during bicarbonate-buffered haemodialysis

Five patients on maintenance haemodialysis were exposed to varyingdegrees of hypernatric dialysate, leading to acute hypernatraemia(plasma sodium concentrations 158 mmol/l to 179 mmol/l). Withthe exception of one patient, who developed pulmonary oedema,symptoms were minimal and in each case hypernatraemia was correctedwithout residual complications. The hypernatric dialysate resultedfrom a granular and less soluble batch of sodium bicarbonatepowder. The extra effort required to dissolve the powder causedCO₂ to be shaken out of solution, producing sodium carbonateand raising the pH. Mixing calcium from the ‘acid’concentrate with excess carbonate in the ‘bicarbonate’concentrate led to rapid precipitation of calcium carbonateon the conductivity monitoring cells. Dialysate conductivitywas incorrectly sensed as low by the coated conductivity cells,so that an increasing amount of ‘acid’ concentrate,with its accompanying electrolytes, was delivered to the patient.When the granular powder was ground to a fine powder, passedthrough a 125 µm sieve and gently dissolved, the machineoperated normally. We recommend that sodium bicarbonate powderis supplied with a sieve size no greater than 125 µm,kept dry to prevent the formation of large crystals, and dissolvedgently.     

Continuous veno-venous haemodialysis with a novel bicarbonate dialysis solution: prospective cross-over comparison with a lactate buffered solution.

OBJECTIVE: To compare acid-base balance, lactate concentration and haemodynamic parameters during continuous veno-venous haemodialysis (CVVHD) using bicarbonate or a lactate buffered dialysate. METHODS: Design: prospective randomized cross-over design; Setting: Multicentre combined adult surgical and medical intensive care units. Patients; 26 critically ill patients starting CVVHD for acute renal failure. Interventions: Each patient to receive 48 h of bicarbonate dialysate and 48 h of lactate dialysate with the order of the 48 h block randomized at trial entry. RESULTS: The serum bicarbonate increased from baseline in both the lactate and bicarbonate groups over the first 48 h of treatment (16.3+/-1.53 to 22.2+/-1.41 mmol/l and 18.9+/-2.02 to 22.2+/-1.18 mmol/l, respectively) and continued to rise towards normal over the next 48 h after cross-over to the other dialysate. The H+ and pCO2 only trended higher in the lactate group. Unlike the acid base parameters, serum lactate levels varied depending on the dialysate composition. The patients initially randomized to the lactate dialysate had higher serum lactate levels and these tended to increase further after 48 h of dialysis from 2.4+/-0.8 to 2.6+/-0.4 mmol/l. However, in the following 48 h the lactate levels fell to 1.8+/-0.6 (P = 0.039) while patients were being treated with the bicarbonate dialysate. Similar results were seen in the patients initially randomized to the bicarbonate dialysate. Serum lactate remained stable over the first 48h (1.4+/-0.2 to 1.5+/-0.1 mmol/l) but after cross-over to the lactate dialysate increased to 3.1+/-0.7 mmol/l (P = 0.051). Overall, lactate levels were significantly higher during dialysis with lactate buffered solution than bicarbonate buffered solution (2.92+/-0.45 vs. 1.61+/-0.25 mmol/l P = 0.01). Mean arterial pressure trended higher during bicarbonate dialysis but did not reach statistical significance (lactate vs. bicarbonate; 71.1+/-3.1 vs. 81.3+/-5.8 mm Hg). Subgroup analysis of the patients with abnormal liver indices or increased lactate levels at initiation of dialysis (n = 15) revealed only a trend toward better bicarbonate control (lactate vs. bicarbonate; 22.00+/-1.73 vs. 22.86+/-1.09, P = 0.2). However, in this group with hepatic insufficiency elevations in serum lactate were even greater during lactate compared to the bicarbonate dialysis (3.39+/-0.68 vs. 1.78+/-0.42 P = 0.036). Patients who had elevations of lactate during lactate dialysis had a high mortality (6 of 7). These patients had an even greater disparity in lactate levels (4.3+/-1.4 vs. 1.3 +/-0.3) and blood pressure (68.0+/- 7.7 vs. 87.2+/-17.1) between lactate and bicarbonate dialysis. Due to small patient numbers these comparisons did not achieve statistical significance. CONCLUSION: During continuous veno venous haemodialysis a bicarbonate buffered dialysis solution provided equal acid-base control but maintained more normal lactate levels than a lactate buffered dialysis solution.     

Orthostatic hypotension at the introductory phase of haemodialysis predicts all-cause mortality.

BACKGROUND: Since the predictive value of orthostatic hypotension (OH) at the introductory phase of haemodialysis (HD) is unknown, we examined the association between OH and all-cause death in patients who started HD between 1987 and 2001. METHODS: More than three consecutive blood pressure measurements before HD treatments (pre-HD BP) were made on each of 304 patients who had recently been started on HD and were in a stable condition. OH was defined as a drop in systolic BP of >20 mmHg or in diastolic BP of >10 mmHg after standing. RESULTS: Of 304 patients, 42% had OH. OH was significantly associated with pre-HD supine systolic BP; its severity was significantly associated with a past history of cerebrovascular disease and pre-HD supine systolic BP. During a mean follow-up of 4.0+/-3.0 years (range 0.1-13.2 years), 136 deaths were recorded. A multivariate Cox proportional hazards model analysis demonstrated that OH and a past history of cerebrovascular disease were independent predictors of all-cause death. The comparison by Kaplan-Meier analysis of the overall survival of patients with and without OH was significant. CONCLUSIONS: Our findings validate OH at the introductory phase of HD as a novel independent predictor of all-cause mortality among HD patients.     

Dynamic changes in right ventricular pressures during haemodialysis recorded with an implantable haemodynamic monitor.

BACKGROUND: Intermittent and chronic volume overload contributes to the development of cardiovascular disease in patients on maintenance haemodialysis (HD). Continuous monitoring of central haemodynamic parameters may provide valuable information to improve volume control, particularly in patients with left ventricular dysfunction. METHODS: Five patients on HD, age 53-76 years, with systolic and/or diastolic dysfunction (EF 20-50%) received an implantable haemodynamic monitor (IHM) (Chronicle model 9520, Medtronic). The IHM consists of a memory device implanted subcutaneously and a transveneous right ventricular (RV) lead carrying a pressure sensor. It continuously records heart rate, RV systolic (RVSP) and diastolic pressures (RVDP), RV dP/dt and an estimate of pulmonary artery diastolic pressure (ePAD). Continuous haemodynamic profiles were recorded in all patients. RESULTS: During dialysis RVSP and ePAD dropped by a mean of 39 and 50%, respectively. RVDP decreased by 6.6 mmHg. The lowest pressures occurred during the first 90 min of dialysis and were partly restored at the end of the procedure. Long-term haemodynamic monitoring unmasked severe volume overload in one patient, when dry weight was kept stable despite a decrease in lean body mass. In another patient with recurrent dyspnea after dialysis, paroxysmal atrial fibrillation, regularly occurring during dialysis, was identified as the cause of symptoms. CONCLUSION: The implanted haemodynamic monitor was a sensitive indicator for changes in volume load. Continuous haemodynamic monitoring may offer a valuable tool to improve volume management in dialysis patients with left ventricular dysfunction.     

Methylene blue, a nitric oxide inhibitor, prevents haemodialysis hypotension.

BACKGROUND: Plasma nitric oxide (NO) levels have been found to be high in haemodialysis (HD) patients, especially in those prone to hypotension in dialysis. The aim of the study was to prevent dialysis hypotension episodes by i.v. administration of methylene blue (MB), an inhibitor of NO activity and/or production. METHODS: MB was given i.v. in 18 stable HD patients with hypotensive episodes during almost every dialysis, in 18 HD patients without hypotension during dialyses, and in five healthy controls. MB was given as a bolus of 1 mg/kg bodyweight followed by a constant infusion of 0.1 mg/kg bodyweight lasting 210 min until the end of the dialysis session and only as a bolus on a non-dialysis day. Systolic and diastolic blood pressures (BP) were measured at 10-min intervals during HD sessions with or without MB and on a non-dialysis day with MB. RESULTS: In hypotension-prone patients, MB completely prevented the hypotension during dialysis and increased both systolic and diastolic BP on non-dialysis days. In normotensive patients, MB increased BP during the first hour of dialysis and for 90 min on the non-dialysis day. The BP in the healthy controls remained unchanged. Plasma and platelet NO(2)+NO(3) (stable metabolites of NO) levels were determined. The NO(2)+NO(3) generation rate in the first post-dialysis day was calculated. The plasma and platelet NO(2)+NO(3) were higher in the hypotensive group than in the normotensive dialysis group. The generation rate of nitrates was higher (P<0.01) in the hypotensive group (1.21+/-0.13 micromol/min and 0.74+/-0.16 after MB) than in the normotensive patients (0.61+/-0.11 micromol/ min and 0.27+/-0.14 after MB). No side-effects were recorded. CONCLUSIONS: MB is an efficient therapy in the prevention of dialysis hypotension.     

The haemodynamic response to submaximal exercise during isovolaemic haemodialysis.

INTRODUCTION: Exercise during haemodialysis has potential benefits but may compromise cardiovascular stability. We studied its acute effects on relative blood volume (RBV) and other haemodynamic parameters. METHODS: Two groups of 10 patients were exercised submaximally using a stationary cycle during isovolaemic dialysis whilst RBV was monitored continuously. In study 1, patients exercised for two 10 min periods separated by 10 min rest. Cardiac output (CO), peripheral vascular resistance (PVR), central blood volume (CBV) and stroke volume were measured using ultrasound dilution immediately before and after each exercise session. In study 2, haemoglobin, serum total protein and albumin levels were measured before and immediately after the exercise session and at the nadir of the RBV trace. RESULTS: RBV fell immediately on exercise initiation, the maximum reduction being 2.0+/-1.1% (after 5.9+/-1.4 min of exercise 1: P<0.001) and 2.0+/-1.2% (after 4.7+/-2.3 min of exercise 2: P<0.001). CO increased significantly after both periods of exercise (4.5+/-0.96 and 5.1+/-1.1 to 7.2+/-2.1 and 7.9+/-2.4 l/min, P<0.001 in both). Stroke volume increased significantly and PVR fell significantly during exercise. CBV increased in absolute terms but fell as a proportion of CO. Mean haemoglobin level at the RBV nadir was significantly higher than baseline (12.3+/-1.8 vs 11.8+/-1.7 g/dl: P<0.05: mean change 4.4+/-2.3%), as was mean total protein concentration (66.0+/-6.9 vs 62.0+/-8.1 g/l: P = 0.001: mean change 6.8+/-5.9%) and mean serum albumin concentration (36.0+/-3.9 vs 34.1+/-3.9 g/l: P<0.001: mean change 5.8+/-3.5%). CONCLUSION: The haemodynamic response to exercise during haemodialysis is comparable with that in normal individuals. The rapid reduction in RBV on exercise occurs in spite of a significant increase in CO, mainly as a consequence of fluid shifts from the microvasculature to the interstitium.     

Sodium modelling and profiled ultrafiltration in conventional haemodialysis

Summary: Previous controlled studies have shown that sodium modelling may reduce intradialytic hypotension and symptoms (particularly cramp, headache and nausea) in patients on maintenance haemodialysis, and it has been proposed that decremental profiled ultrafiltration may improve haemodynamic stability. Those controlled studies of sodium modelling were flawed because sodium modelling programmes were compared to a constant sodium dialysate concentration lower than the overall mean sodium concentration during sodium modelling (the ‘true mean’). to compare sodium modelling to its true mean constant dialysate concentration and also to compare profiled ultrafiltration with constant ultrafiltration, 12 patients on conventional haemodialysis were dialysed by four regimens in random order each for 3 weeks: (i) sodium modelling (exponential decline from 150 to 140 mmol/L) and conventional (linear) ultrafiltration; (ii) sodium modelling and profiled (65% of target loss in first 2 h) ultrafiltration; (iii) constant sodium (143 mmol/L, the true mean) and conventional ultrafiltration; and (iv) constant sodium and profiled ultrafiltration. Weight gain and pre-dialysis blood pressure were no different between the four regimens. Sodium modelling had no effect on the frequency of intradialytic hypotension or need for saline administration when compared to a constant sodium dialysate of 143 mmol/L, nor improved frequency or severity of thirst, cramp, nausea and lethargy. Interdialytic headache was less severe (P<0.05) but no less frequent with sodium modelling. Profiled ultrafiltration increased the frequency of intradialytic hypotension (odds ratio 2.44, P<0.05) and did not improve symptoms except interdialytic thirst, which occurred less frequently than with linear ultrafiltration (odds ratio 0.55, P<0.05). the haemodynamics and symptoms were no better with sodium modelling and profiled ultrafiltration than with constant sodium dialysis and linear ultrafiltration, respectively. Thus, there is no justification for the routine use of sodium modelling or profiled ultrafiltration in conventional haemodialysis on the grounds of haemodynamic stability or symptom control.     

Factors associated with mortality in patients new to haemodialysis.

BACKGROUND: Patients receiving dialysis therapy for end-stage kidney failure have a high cardiovascular mortality that can only be partially explained by traditional risk factors. METHODS: This study was a post hoc analysis of a prospectively gathered data set from a randomized trial comparing outcomes in new haemodialysis patients treated with sevelamer or calcium-containing phosphate binders. Patients were followed from the time of enrollment until death or censor on 31 December 2005. Median follow-up was 3.6 years. Demographics, cardiovascular risk factors, laboratory data, medication use and severity of vascular calcification were available at baseline and over the first 18 months of dialysis. RESULTS: Baseline predictors of mortality included age, creatinine, heart rate, iPTH, C-reactive protein (CRP), coronary and aortic calcium scores and the presence of aortic valve calcification. Over the first 18 months, averages of diastolic blood pressure, BUN, creatinine, albumin, phosphorus, iPTH and CRP were all significantly different between survivors and non-survivors. A stepwise multivariable adjusted Cox regression model demonstrated that low BUN and albumin and high CRP along with the use of calcium-containing phosphate binders (rather than sevelamer) were the strongest predictors of mortality in patients new to haemodialysis. CONCLUSIONS: These findings suggest that non-traditional risk factors, such as inflammation and malnutrition measured during the first 18 months of dialysis, are important determinates of survival in new dialysis patients. In addition, the unique risk factor for dialysis patients, the use of calcium-containing phosphate binders, was associated with a higher mortality rate in patients new to dialysis.     

Efficacy and safety of haemodialysis treatment with the Hemocontrol biofeedback system: a prospective medium-term study.

BACKGROUND: Hypovolaemia has been implicated as a major causal factor of morbidity during haemodialysis (HD). A model biofeedback control system for intra-HD blood volume (BV) changes modelling has been developed (Hemocontrol), Hospal Italy) to prevent destabilizing hypovolaemia. It is based on an adaptive controller incorporated in a HD machine (Integra), Hospal Italy). The Hemocontrol biofeedback system (HBS) monitors BV contraction during HD with an optical device. HBS modulates BV contraction rates by adjusting the ultrafiltration rate (UFR) and the refilling rate by adjusting dialysate conductivity (DC) in order to obtain the desired pre-determined BV trajectories. METHODS: Nineteen hypotension-prone uraemic patients (seven males, 12 females; mean age 64.5+/-3.0 SEM years; on maintenance HD for 80.5+/-13.2 months) volunteered for the present prospective study that compared the efficacy and safety of bicarbonate HD treatment equipped with HBS, as a whole, with the gold-standard bicarbonate treatment equipped with a constant UFR and DC (BD). The study included three phases: Medium-term studies started with one period of 6 months of BD and always had a follow-up period of HBS treatment ranging from 14 to 30 months (mean 24.0+/-1.6); short-term studies started in September 1999, when all patients went back to BD treatment for a wash-out period of 4 weeks and a short-term study period of a further 3 weeks (phase A). Afterwards, they once again started HBS treatment for a wash-out period of 4 weeks and a short-term study period of a further 3 weeks (phase B). Every patient underwent acute studies during a single HD run, once during phase A and once in phase B. Resistance (R) and reactance (Xc) measurements were obtained utilizing a single-frequency (50 kHz) tetrapolar bioimpedance analysis (BIA). Extracellular fluid volume (ECV) was calculated from R, Xc, and height and body weight measurements using the conventional BIA regression equations. RESULTS: The overall occurrence of symptomatic hypotension and muscle cramps was significantly less in HBS treatment in both medium- and short-term studies. Self-evaluation of intra- and inter-HD symptoms (worst score=0, best score=10) revealed a statistically significant difference, as far as post-HD asthenia was concerned (6.2+/-0.2 in HBS treatment vs 4.3+/-0.1 in BD treatment, P<0.0001). No difference was observed between the two treatments when comparing pre- and post-HD lying blood pressure, heart rate, body weights and body weight changes in medium- and short-term studies. The residual BV%/ Delta ECV% ratio, expression of the vascular refilling, was significantly higher during HBS treatment in acute studies. CONCLUSIONS: HBS treatment is effective in lowering hypovolaemia-associated morbidity compared with BD treatment; this could be related to a greater ECV stability. Furthermore, HBS is a safe treatment in the medium-term because these results are not achieved through potentially harmful changes in blood pressure, body weight, and serum sodium concentration.     

Assessment of intra-operative haemodynamic changes associated with transhiatal and transthoracic oesophagectomy

Objective: Previous comparisons of the different surgical techniques for oesophagectomy have concentrated on mortality, morbidity and survival. There is limited data regarding the intra-operative physiological ramifications of the transhiatal (TH) versus the transthoracic (TT) approach to oesophageal resection. We carried out an in-depth analysis of the intra-operative haemodynamic changes and assessed the potential implications on perioperative outcomes in a matched cohort of patients undergoing TH and TT oesophagectomy. Methods: A retrospective case review study of TT and TH oesophageal resection at a high-volume tertiary referral centre for oesophageal diseases. General demographics and outcomes of the patients were accumulated prospectively in an Institutional Review Board (IRB) approved database. Intra-operative haemodynamic measurements were obtained from anaesthetic records. A total of 40 patients (20 TT + 20 TH) were retrospectively identified after matching them for age, co-morbidities, tumour stage and American Society of Anesthesiologists (ASA) status. Main outcome measures included perioperative outcomes, operative time, blood loss, intensive care unit (ICU) and hospital length of stay, incidence and types of dysrhythmias, incidence of intra-operative hypotension and vasopressor usage, as well as perioperative morbidity and 90-day mortality. Results: Indications for resection included oesophageal cancer (27 patients), high-grade dysplasia (six patients), laryngopharyngoesophageal cancer (three patients), achalasia (two patients) and scleroderma (1 patient). Nine patents with oesophageal cancer had pT3 tumours (TH1, TT8). The mortality was zero in both groups. The total duration of hospitalisation and ICU care was similar in both groups. The mean estimated blood loss was 213 ml (range 100–400 ml) for the TH group and 216 ml (range 80–500 ml) for the TT group. The median operating times for both approaches were similar (398 min TH vs 382 min TT). Intra-operative dysrhythmias were noted in 11 TH and 15 TT patients. Both groups maintained at least 80% of the pre-operative systolic blood pressure (SBP) intra-operatively (TT 89% vs TH 85%) and required vasopressors in comparable quantities. The comparative statistical analysis of intra-operative incidences of hypotensive episodes below 100, 90 and 80 mm Hg showed no significant differences in both groups. However, the TH group experienced a greater frequency of acute hypotension (acute SBP decreases by ≥10 mm Hg per 5-min reading) intra-operatively (TH 25% vs TT 16% of operative time), p = 0.02. Phenylephrine infusions were required for longer periods in the TH group (TH 52.7% vs TT 33.6% of operation time), p = 0.01. Conclusion: This study demonstrates that intra-operative haemodynamic changes and perioperative outcomes are similar in both TT and TH approaches for oesophagectomy in a well-matched cohort of patients. Patients undergoing the TH approach demonstrated a higher frequency of intra-operative haemodynamic lability. The approaches to oesophageal resection should be based on matching the operation to the patient's pre-existing conditions and tumour characteristics rather than perceived differences in haemodynamic impact.     

A prospective study of complications associated with cuffed, tunnelled haemodialysis catheters.

BACKGROUND: Despite the US Dialysis Outcome Quality Initiative )DOQI( guidelines, for various reasons, increasing numbers of end-stage renal disease patients are becoming dependent on cuffed haemodialysis catheters (HCs) for chronic haemodialysis access. Their use is complicated by frequent failure due to thrombosis and catheter-related sepsis. In our unit, all HCs are put in place by the radiology department. METHODS: In a prospective study we looked at the outcome of all HCs over a three-year period, during which time 573 consecutive HCs were placed in 336 patients. Each line was followed individually until it was removed or until the end of the study. RESULTS: In a survival analysis of those HCs removed following HC failure, HC half-life was 312 days and one-year HC survival was 47.5%. The most frequent indications for HC removal were non-function (36.6%), clinical suspicion of line sepsis (16.4%) and patient death (14.4%). Using a Cox proportional hazards model, catheter number in a given patient and the presence of diabetes mellitus were found to be independent predictors of HC failure. The total incidence of HC-related sepsis was 1.3 episodes/1000 catheter days. The probability of developing bacteraemic HC-related sepsis was 27.5% at one year. CONCLUSIONS: Less than half of the HCs were removed electively because of availability of a more permanent mode of renal replacement, thereby illustrating the level of dependence that has developed on them as permanent access. Consequently, their limitations (infection and malfunction) are placing an ever increasing burden on the healthcare services.     

Creatine monohydrate treatment alleviates muscle cramps associated with haemodialysis.

BACKGROUND: Muscle cramp is a common complication of haemodialysis. The exact mechanism of this complication is still unknown. Many approaches have been used to relieve the muscle cramping but have had variable effects. One of the possible mechanisms of haemodialysis-associated muscle cramps (HAMC) is the disturbance of muscle energy metabolism. Creatine monohydrate can enhance muscle metabolism. We evaluated the clinical effect of creatine monohydrate on HAMC. METHODS: Ten patients with frequent muscle cramps during haemodialysis were randomly selected into two groups, control and placebo. In a double-blind manner, 12 mg of creatine monohydrate or placebo was given to each patient before each dialysis session for 4 weeks. The incidence of muscle cramp during haemodialysis was compared between the two groups. Dialysis adequacy, haemodynamic status, and side-effects were also evaluated. We continued to observe and compare the patients during a 4-week washout period to verify the effect of creatine monohydrate. RESULTS: The frequency of symptomatic muscle cramps decreased by 60% in the creatine monohydrate treatment group (6.2+/-0.8 vs 2.6+/-1.8 times/4 weeks, P<0.05) during the treatment period. This decreasing incidence of muscle cramps disappeared in the washout period in the creatine group (6.6+/-1.1 times/4 weeks). There was no difference in the incidence of muscle cramps in the placebo group. The haematocrit, Kt/V, serum albumin, and haemodynamics remained unchanged in both groups during the treatment and washout periods. Serum creatinine increased slightly after creatine monohydrate treatment (10.7+/-3.2 vs 12.4+/-3.2 mg/dl, P<0.05). No adverse effect was found in either group during the treatment and washout periods. CONCLUSION: These data suggest that creatine monohydrate can reduce the incidence of HAMC and that it may be a safe agent.