Serum Bicarbonate Concentration Research Articles

Patients receiving maintenance dialysis have more severe functionally significant skeletal muscle wasting than patients with dialysis-independent chronic kidney disease

Chronic renal replacement therapy patients exhibit reduction in skeletal muscle function as a result of a combination of metabolic effects and muscle fibre size reduction. The aim of this study was to compare muscle mass with function in patients with chronic kidney disease (CKD) at stages 4 and 5 on haemodialysis (HD) and peritoneal dialysis (PD), and investigate the associations of muscle wasting in a cross-sectional cohort. We studied 134 patients (60 HD, 28 PD and 46 CKD 4). The three groups were well matched for age, sex, diabetes and dialysis vintage. Cross-sectional area (CSA) of muscle and fat was measured from a standardized multi-slice CT scan of a 6 cm long section of thigh. CSA of soft tissue was taken from appropriate fat and muscle densities. Functional assessment was by the sit-to-stand 60 test, assessing both the number of sit-to-stands possible under controlled conditions in 60 s (STS 60), and the time taken to perform five sit-to-stand movements (STS 5). Data were collected on a wide range of potential determinants of muscle CSA. There were no significant differences in haemoglobin between males or females or between any of the groups studied. Serum phosphate and calcium-phosphate product were higher in HD patients as compared to CKD4 patients, but there were no differences in these variables when comparing PD patients with either CKD4 or HD patients. Muscle CSA correlated well with objective functional assessments in males (STS 60 R = 0.52, P<0.0001) and females (R = 0.41, P = 0.004), and STS performance was reduced in dialysed patients as compared with CKD 4. Univariate analysis demonstrated that muscle CSA was associated with serum albumin concentration (R = 0.49, P<0.0001), age (R = -0.35, P = 0.005) and C-reactive protein (R = -0.34, P = 0.004). Creatinine clearance, dialysis adequacy, dialysis vintage and time-averaged serum bicarbonate, calcium and phosphate concentrations were not correlated with muscle CSA. In conclusion, patients with dialysis-treated CKD 5 exhibited more functionally significant muscle wasting than patients with CKD 4. This may be amenable to modification with targeted exercise or amelioration of factors associated with observed differences in muscle mass.

Use of sodium concentration and anion gap to improve correlation between serum chloride and bicarbonate concentrations

Although most acid-base disorders cause opposite and equal changes in serum chloride and bicarbonate concentrations, this inverse relationship can be distorted by changes in the anion gap and/or water balance. Therefore, we examined the relationship between chloride and bicarbonate before and after adjusting for anion gap and serum sodium concentration. Patients with abnormal electrolytes were grouped by chloride and bicarbonate concentrations (low, normal, and high). Then, chloride and anion gap-adjusted bicarbonate were adjusted for water excess (or deficit), manifesting as hyponatremia (or hypernatremia), after which patients were reclassified. Classification by chloride and bicarbonate changed in 82% of the 135 patients after adjustment for anion gap and sodium. Serum chloride and bicarbonate were each low (concordant) in 23 patients, while 18 had discordant chlorides and bicarbonates (9 low/high, 9 high/low). After adjustments, chloride and bicarbonate were discordant in 40 patients (31 low/high, 9 high/low) and concordant in none. The correlation between serum chloride and bicarbonate improved from -0.459 to -0.998 after adjustments for sodium and anion gap. A very close inverse relationship between serum chloride and bicarbonate concentrations is commonly distorted by concomitant water disturbances and anion gap acidoses in internal medicine patients admitted with electrolyte disorders.

Hyperglycemic Comas in Children: New Insights into Pathophysiology and Management

The hyperglycemic comas in pediatric patients, ketoacidosis (DKA), occurring with both type 1 and type 2 diabetes, and hyperglycemic hyperosmolar state (HHS), which occurs almost exclusively with type 2 diabetes, account for most of the diabetes related morbidity and mortality in childhood. DKA is defined as acidosis measured as venous pH 11 mmol/L. This is typically associated with glucosuria, ketonuria, and ketonemia. Near normal circulating glucose concentrations may occur rarely in DKA with partial treatment or with pregnancy [1]. HHS was formerly referred to as hyperglycemic hyperosmolar nonketotic state, but the nomenclature was changed to recognize the frequent presence of mild ketosis. Indeed, diabetic comas can be viewed as a continuum from DKA with normal osmolality to HHS without ketosis [2]. The emergence of type 2 diabetes in childhood, accounting for as much as 50% of newly-diagnosed diabetes in the 10–19 year age group, depending on socioeconomic and ethnic composition of the population, has resulted in an appreciation of HHS as no longer a condition seen rarely outside of elderly populations [3,4]. The criteria for HHS include plasma glucose concentration >33.3 mmol/L, serum bicarbonate concentration >15 mmol/L, no or small ketonuria, absent to small ketonemia, effective serum osmolality greater than 320 mOsm/kg, and stupor or coma [2].

Metabolic Acidosis in Peritoneal Dialysis Patients: The Role of Residual Renal Function

Background: Metabolic acidosis (MA) is common in chronic renal insufficiency (CRI) patients, and its pattern changes as renal function deteriorates. Although the prevalence of acidosis in peritoneal dialysis has been reported to be rather high, the causes of it have not been well studied. The present study was performed to examine the prevalence of metabolic acidosis in our continuous ambulatory peritoneal dialysis (CAPD) patients and its possible causes. Methods: In this cross-sectional study, we analyzed data from patients who received maintenance CAPD in our hospital and had been on dialysis for at least one month. Patients’ demographic features, medications, and intercurrent medical conditions were recorded. Data including blood biochemistry, dialysis adequacy, and nutrition were collected. A serum bicarbonate concentration of less than 23 mmol/l was defined as having acidosis. The normal value of the serum anion gap (AG) was defined as 12 ± 4 mmol/l. Results: A total of 154 patients (76 males and 78 females) with age of 60.04 ± 13.92 years and the time on dialysis of 16.83 ± 21.59 months were included in this study. Sixty-six patients (43%) had a serum bicarbonate of less than 23 mmol/l, among whom 12 patients (8%) were identified as having MA with increased AG, 54 (35%) were identified as having MA with normal AG. Patients who had better residual renal function (RRF) had a significantly lower serum bicarbonate level despite their higher total KT/V_urea as compared to those with lower RRF. In addition, patients with MA and normal AG had the highest RRF and highest total KT/V_urea. All patients with MA and increased AG had significantly lower values of dietary protein intake (DPI) as compared to their values of normalized protein nitrogen appearance (nPNA), and had higher serum urea and phosphate levels as compared with those patients without MA. Conclusion: Our study suggested that CAPD patients with better RRF were more susceptible to metabolic acidosis, which was characterized by normal anion gap and hyperchloremia. Thus, we speculate that renal loss of bicarbonate may to a large extent be responsible for the occurrence of MA in these patients.

Effect of Dietary Protein Intake on Serum Total CO2 Concentration in Chronic Kidney Disease

Metabolic acidosis is a feature of chronic kidney disease (CKD), but whether serum bicarbonate concentration is influenced by variations in dietary protein intake is unknown. For assessing the effect of diet, data that were collected in the Modification of Diet in Renal Disease study were used. In this study, patients with CKD were enrolled into a baseline period, then randomly assigned to follow either a low- or a usual-protein diet (study A, entry GFR 25 to 55 ml/min) or a low- or very low-protein diet, the latter supplemented with ketoanalogs of amino acids (study B, entry GFR 13 to 24 ml/min). Serum [total CO2] and estimated protein intake (EPI) were assessed at entry (n = 1676) and again at 1 yr after randomization, controlling for changes in GFR and other key covariates (n = 723). At entry, serum [total CO2] was inversely related to EPI (1.0 mEq/L lower mean serum [total CO2]/g per kg body wt increase in protein intake/d; P = 0.009). In an intention-to-treat analysis, the reduction in mean EPI in the low-protein group as compared with the usual-protein group (0.41 g/kg body wt per d) was independently associated with a 0.9-mEq/L increase in serum [total CO2], after adjustment for covariates (P < 0.001). No such effect was evident in study B, in which the very low-protein diet group received dietary supplements. Serum [total CO2] is inversely correlated with dietary protein intake in patients with CKD. A reduction in protein intake results in an increase in serum [total CO2].

Análise prospectiva de risco em pacientes submetidos à cirurgia de revascularização miocárdica

To perform a stratified risk analysis in Myocardial Revascularization Surgery (MRS). 814 patients were prospectively studied by applying two prognostic indexes (PI): Parsonnet and Modified Higgins. The Higgins PI was modified by substituting the variable "cardiac index value" by "low cardiac output syndrome" at the Intensive Care Unit (ICU) admission. The discriminatory capacity for morbimortality of both indexes was analyzed by ROC (receiver operating characteristic) curve. Logistic reaction identified the associated factors, independently from the events. Mortality and morbidity rates were 5.9% and 35.5%, respectively. The Modified Higgins PI, which analyzes pre- and intra-operative and physiological variables at the ICU admission showed areas under the ROC curve of 77% for mortality and 67% for morbidity. The Parsonnet PI, which only analyzes pre-operative variables, showed areas of 62.2% and 62.4%, respectively. Twelve variables were characterized as independent prognostic factors: age, diabetes mellitus, low body surface, creatinine levels (>1.5 mg/dL), hypoalbuminemia, non-elective surgery, prolonged time of extracorporeal circulation (ECC), necessity of post-ECC intra-aortic balloon, low cardiac output syndrome at the ICU admission, elevated cardiac frequency, decrease in serum bicarbonate concentrations and increase of the alveolar-arterial oxygen gradient within this period. The Modified Higgins PI showed to be superior to the Parsonnet PI at the surgical risk stratification, showing the importance of the analysis of intraoperative events and physiological variables at the patient's ICU admission, when prognostic definition is achieved.

Trichophytobezoar Duodenal Obstruction in New World Camelids

To describe clinical findings, surgical treatment, and outcome associated with trichophytobezoar duodenal obstruction in New World camelids. Retrospective study. Alpacas (7) and 1 llama. Historical and clinical data were obtained from the medical records of New World camelids with a diagnosis of trichophytobezoar duodenal obstruction confirmed by surgical exploration or necropsy. Seven camelids were <1 year old. Abnormal clinical findings included anorexia, reduced fecal output, recumbency, colic, abdominal distension, regurgitation, decreased serum chloride concentration, increased serum bicarbonate concentration, and/or elevated first gastric compartment chloride concentration. Survey abdominal radiographs obtained (4 animals) revealed gastric distension (4) and/or visualization of the obstruction (2). Diagnosis was confirmed at necropsy (1) or surgery (7). Right paracostal celiotomy was performed on all animals and duodenotomy (3) or retropulsion of the trichophytobezoar combined with third compartment gastrotomy (4) was used to remove the obstruction. Six animals survived to discharge and 5 were healthy at follow-up, 8-20 months later. The remaining discharged alpaca was healthy at 12 months but subsequently died of unrelated causes. Diagnosis of trichophytobezoar duodenal obstruction should be considered in juvenile New World camelids with abdominal distension and hypochloremic metabolic alkalosis. Right paracostal celiotomy can be used for access to the descending duodenum and third gastric compartment for surgical relief of obstruction. Duodenal obstruction from bezoars should be considered in New World camelids <1year of age with abdominal distension and hypochloremic metabolic alkalosis. Surgical relief of the obstruction by right paracostal celiotomy has a good prognosis.

Changes in acid-base balance following bolus infusion of 20% albumin solution in humans

To evaluate changes in acid-base balance following bolus infusions of a 20% albumin solution. Randomized prospective study in a university hospital. Two groups of eight patients each undergoing gynecological surgery. Patients were randomly assigned to receive either 0.9% saline or lactated Ringer's solution. At the end of surgery two boluses of 0.5 g/kg body weight of a 20% albumin solution were administered. Arterial blood gases, electrolytes, and total protein were measured. The strong ion difference and the amount of weak plasma acid were calculated. pH and titratable acidity of the 20% albumin solution were determined. The infusion of a 20% albumin solution resulted in a significant decrease in pH from 7.284 to 7.262 in the saline group and from 7.422 to 7.394 in the Ringer's group. In both groups the 20% albumin solution caused an increase in strong ion difference and an increase in the amount of weak plasma acid. The observed changes in serum bicarbonate concentration were in good agreement with the changes in strong ion difference and the amount of weak plasma acid. The 20% albumin solution possessed a pH of 6.95 and a titratable acidity of 8.5 [corrected] mEq/l. According to the Stewart approach, the observed changes in acid-base balance are the net result of the two opposing effects of the strong ion difference and the amount of weak plasma acid. Alternatively, the acidifying effect of the 20% albumin solution may stem from the titratable acid content of the solution.

Predictive factors of low HCO3– levels in peritoneal dialysis patients

Metabolic acidosis is a major metabolic abnormality in end-stage renal disease (ESRD) and alkali is provided with dialysis treatment to patients on chronic peritoneal dialysis (CPD) to keep their acid-base balance within normal serum HCO3- levels. We examined the levels of venous serum HCO3- in 163 patients on CPD and the predictive factors for HCO3- levels low enough to indicate metabolic acidosis. The mean value for HCO3- was 26+/-2.4 mmol/l and for anion gap was 13.1+/-3.1 mEq/l. A serum bicarbonate concentration of less than 24 mmol/l, compatible with metabolic acidosis, was observed in 13.5% of the patients. In a multivariate analysis HCO3- levels were directly correlated with older age and use of CaCO3- as phosphate binders, and inversely associated with serum potassium, the use of sevelamer and low lactate dialysis solutions. Higher serum urea levels, the use of low lactate solutions and sevelamer instead of CaCO3 were significantly predictive factors for HCO3- levels < 24 mmol/l. Venous HCO3- and anion gap values were within the normal ranges in stable CPD patients. In 13.5% of them, however, chronic metabolic acidosis was observed based on venous HCO3- levels < 24 mmol/l. Dietary protein intake, the use of sevelamer and low (35 mmol/l) concentration of lactate in dialysis solutions are important predictive factors for chronic metabolic acidosis in these patients.

Impact of Topiramate on Serum Bicarbonate Concentrations in Adults

Topiramate is an antiepileptic medication with multiple pharmacologic effects, including inhibition of carbonic anhydrase activity. It is associated with metabolic acidosis in both children and adults. To evaluate the incidence and magnitude of the effect of topiramate on serum bicarbonate concentrations in an adult population. This was a retrospective cohort study. Data were evaluated to assess the relationship between serum bicarbonate concentrations before and during topiramate therapy. Fifty-four patients (40 females) with a mean age of 47.6 years (range 19-89) were included in the study. Mean +/- SD serum bicarbonate concentrations before and during topiramate therapy were 26.8 +/- 2.9 mEq/L (range 21-36) and 21.7 +/- 3.6 mEq/L (range 13-29), respectively, with a mean difference of 5.1 (95% CI 3.7 to 6.5; p < 0.001). Twenty-six patients (48%) had low serum bicarbonate concentrations while on topiramate, with a mean concentration of 18.8 mEq/L (range 13-21). Topiramate was associated with metabolic acidosis in 48% of the patients studied, which did not result in clinically significant problems.

POOR NUTRITIONAL STATUS AND INFLAMMATION: Metabolic Acidosis and Malnutrition‐Inflammation Complex Syndrome in Chronic Renal Failure

ABSTRACTMetabolic acidosis, a common condition in patients with renal failure, may be linked to protein‐energy malnutrition (PEM) and inflammation, together also known as malnutrition‐inflammation complex syndrome (MICS). Methods of serum bicarbonate measurement may misrepresent the true bicarbonate level, since the total serum carbon dioxide measurement usually overestimates the serum bicarbonate concentration. Moreover, the air transportation of blood samples to distant laboratories may lead to erroneous readings. In patients with chronic kidney disease (CKD) or end‐stage renal disease (ESRD), a significant number of endocrine, musculoskeletal, and metabolic abnormalities are believed to result from acidemia. Metabolic acidosis may be related to PEM and MICS due to an increased protein catabolism, decreased protein synthesis, endocrine abnormalities including insulin resistance, decreased serum leptin level, and inflammation among individuals with renal failure. Evidence suggests that the catabolic effects of metabolic acidosis may result from an increased activity of the adenosine triphosphate (ATP)‐dependent ubiquitin‐proteasome and branched‐chain keto acid dehydrogenase. In contrast to the metabolic studies, many epidemiologic studies in maintenance dialysis patients have indicated a paradoxically inverse association between mildly decreased serum bicarbonate and improved markers of protein‐energy nutritional state. Hence metabolic acidosis may be considered as yet another element of the reverse epidemiology in ESRD patients. Interventional studies have yielded inconsistent results in CKD and ESRD patients, although in peritoneal dialysis patients, mitigating acidemia appears to more consistently improve nutritional status and reduce hospitalizations. Large‐scale, prospective randomized interventional studies are needed to ascertain the potential benefits of correcting acidemia in malnourished and/or inflamed CKD and maintenance hemodialysis patients. Until then, all attempts should be made to adhere to the National Kidney Foundation Kidney Disease and Dialysis Outcome Quality Initiative guidelines to maintain a serum bicarbonate level in ESRD patients of at least 22 mEq/L.

Association of predialysis serum bicarbonate levels with risk of mortality and hospitalization in the Dialysis Outcomes and Practice Patterns Study (DOPPS)

Experimental and some clinical data suggest that metabolic acidosis contributes to poor nutritional status, a strong predictor for mortality in hemodialysis patients. However, recent cross-sectional studies indicate that severe predialysis metabolic acidosis is associated with a greater normalized protein catabolic rate (nPCR) and greater serum albumin levels. Given this controversy, we analyzed data from the Dialysis Outcomes and Practice Pattern Study (DOPPS) for associations between predialysis serum bicarbonate and albumin concentrations, nPCR, and patient risk for mortality and hospitalization. Data from more than 7,000 representative and randomly selected hemodialysis DOPPS patients from France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States were analyzed. Serum bicarbonate (total CO2 ) levels predialysis were corrected to the midweek interdialytic interval. The midweek predialysis serum bicarbonate level averaged 21.9 mEq/L (mmol/L) and correlated inversely with nPCR, serum albumin, and serum phosphorus values. Before and after adjusting for 15 comorbidities, nutrition, and equilibrated Kt/V, a U-curve best represented the association between predialysis serum bicarbonate level and risk for mortality or hospitalization. Patients with midweek predialysis serum bicarbonate levels of 20.1 to 21.0 mEq/L (mmol/L) faced the lowest risk for mortality, whereas those with bicarbonate levels of 21.1 to 22.0 mEq/L faced the lowest risk for hospitalization. Both high (>27 mEq/L) and low (< or =17 mEq/L) serum bicarbonate levels were associated with increased risk for mortality and hospitalization. Moderate predialysis acidosis seems to be associated with better nutritional status and lower relative risk for mortality or hospitalization than is observed in patients with normal ranges of midweek predialysis serum bicarbonate concentration (approximately 24 mEq/L) or severe acidosis (<16 mEq/L).

Two Reports of Propofol Anesthesia Associated with Metabolic Acidosis in Adults

Two Reports of Propofol Anesthesia Associated with Metabolic Acidosis in Adults

Consultation with the Specialist

Consultation with the Specialist

Non-Invasive Pressure Support Ventilation in Patients with Respiratory Failure due to Severe Acute Cardiogenic Pulmonary Edema

Background: Recent studies suggest the use of non-invasive pressure support ventilation (NIPSV) in patients with acute cardiogenic pulmonary edema (ACPE). However, it remains unclear whether all patients with ACPE benefit from NIPSV. Objectives: To investigate short-term effects of NIPSV on respiratory, hemodynamic and oxygenation parameters in patients with respiratory failure due to severe ACPE and to identify factors predicting the need for intubation and in-hospital mortality. Methods: In a prospective, uncontrolled, open study, 28 patients admitted with signs and symptoms of severe respiratory distress due to ACPE were given NIPSV in addition to standardized pharmacological treatment. Physiological parameters were obtained before and after NIPSV, and intubation rate and in-hospital mortality were recorded. Results: NIPSV increased arterial oxygenation from paO₂ 54.2 ± 12.4 to 76.9 ± 12.6 mm Hg (p = 0.0001) and decreased respiratory frequency from 40.1 ± 8.2 to 22.4 ± 4.9 breaths/min (p = 0.0001). Significant improvements were also noted for heart rate, blood pressure and the paO₂/FiO₂ ratio. Four patients (14%) required intubation despite NIPSV. Patients who required intubation had lower paCO₂ levels (p = 0.0002), lower serum bicarbonate concentrations (p = 0.04) and lower systolic blood pressure (p = 0.045) than patients who were successfully treated with NIPSV. Eight patients (28.5%) died during hospitalization. In patients with a paCO₂ ≤35 mm Hg on admission, the in-hospital mortality was 87%, but in patients with a paCO₂ >35 mm Hg the in-hospital mortality was 6%. Conclusions: NIPSV improves oxygenation and alleviates respiratory distress in patients with respiratory failure due to severe ACPE. However, a subgroup of patients with hypocapnia on admission might have a poor prognosis, with a higher risk of intubation and in-hospital mortality.

Body weight, hematologic findings, and serum and plasma biochemical findings of horses competing in a 48-, 83-, or 159-km endurance ride under similar terrain and weather conditions.

To compare physiologic, hematologic, and selected serum and plasma biochemical variables obtained from horses competing in 48-, 83-, or 159-km endurance rides before competition and at the same cumulative distance points. 83 horses. Weight and rectal temperature measurements and blood samples were obtained from horses before, during, and after 1 of 3 rides conducted on the same day. Plasma protein (PP), lactate, WBC, serum electrolyte, and calcium concentrations; PCV; and creatine kinase (CK) activity were determined. Assessments were made to determine whether any differences among groups, with respect to total distance competed, could be explained by differences in lap speed or conditioning and to investigate the effect of time in transit or on-site prior to competition on results of blood analyses or competition outcome. Horses in the 159-km distance group had the lowest preride serum sodium, chloride, bicarbonate, and calcium concentrations. As hours in transit increased, preride PP concentration was significantly greater; serum sodium, chloride, and bicarbonate concentrations were lower; CK activity at 159 km was greater; and horses were more likely to be eliminated. The preride sodium was significantly greater in horses that completed the ride, compared with those eliminated. Among distance groups, distance ridden, speed, level of fitness, and years of experience of horses had little effect on the variables examined. Electrolyte and water supplementation and earlier arrival at the event may be beneficial for horses that are transported long distances to endurance competition.

Yersinia septic shock following an autologous transfusion in a pediatric patient

Although the literature on infections transmitted via transfused blood focuses on viruses, Yersinia enterocolitica can also cause severe infections in patients receiving transfusions. A 13-year-old patient developed severe sepsis after an autologous blood transfusion contaminated with Y. enterocolitica. The patient was an otherwise healthy female undergoing posterior spinal fusion for congenital scoliosis. Prior to surgery, the patient donated blood for perioperative and postoperative use. A few days before the donation, she had complained of abdominal pain and was experiencing mild diarrhea. The patient received four units of packed red blood cells (PRBCs) during the surgery. Intraoperatively, the patient developed fever up to 103.6 °F, became hypotensive requiring epinephrine and dopamine, and developed metabolic acidosis with serum bicarbonate concentration dropping to 16 mmol/l. The surgery team believed the patient was experiencing malignant hyperthermia and attempted to cool patient during the procedure. Postoperatively, the patient was transferred to the pediatric intensive care unit and treated for severe shock of unknown etiology. The patient further developed disseminated intravascular coagulation. The patient received supportive care and was started on ampicillin/sulbactam on postoperative day (POD) one which was changed to clindamycin, ciprofloxacin and tobramycin on POD two when blood cultures grew gram-negative bacilli. On POD three, cultures were identified as Y. enterocolitica and antibiotics were changed to tobramycin and cefotaxime based on susceptibility data. Sequelae of the shock included adult respiratory distress syndrome requiring intubation and a tracheostomy and multiple intracranial hemorrhagic infarcts with subsequent seizure disorder. Due to severe lower extremity ischemia, she required a bilateral below the knee amputation. The cultures of the snippets from the bags of blood transfused to the patient also grew Y. enterocolitica. This case illustrates the importance of considering transfusion related bacterial infections in patients receiving PRBCs. All patients in shock following any type of transfusion may require aggressive antibiotic therapy, until the diagnosis and etiology are known.

(Ab)normal saline and physiological Hartmann’s solution: a randomized double-blind crossover study

In this double-blind crossover study, the effects of bolus infusions of 0.9% saline (NaCl) and Hartmann's solution on serum albumin, haematocrit and serum and urinary biochemistry were compared in healthy subjects. Nine young adult male volunteers received 2-litre intravenous infusions of 0.9% saline and Hartmann's solution on separate occasions, in random order, each over 1h. Body weight, haematocrit and serum biochemistry were measured pre-infusion and at 1h intervals for 6h. Biochemical analysis was performed on pooled post-infusion urine. Blood and plasma volume expansion, estimated by dilutional effects on haematocrit and serum albumin, were greater and more sustained after saline than after Hartmann's solution (P<0.01). At 6h, body weight measurements suggested that 56% of the infused saline was retained, in contrast with only 30% of the Hartmann's solution. Subjects voided more urine (median: 1000 compared with 450ml) of higher sodium content (median: 122 compared with 73mmol) after Hartmann's than after saline (both P = 0.049), despite the greater sodium content of the latter. The time to first micturition was less after Hartmann's than after saline (median: 70 compared with 185min; P = 0.008). There were no significant differences between the effects of the two solutions on serum sodium, potassium, urea or osmolality. After saline, all subjects developed hyperchloraemia (>105mmol/l), which was sustained for >6h, while serum chloride concentrations remained normal after Hartmann's (P<0.001 for difference between infusions). Serum bicarbonate concentration was significantly lower after saline than after Hartmann's (P = 0.008). Thus excretion of both water and sodium is slower after a 2-litre intravenous bolus of 0.9% saline than after Hartmann's solution, due possibly to the more physiological [Na+]/[Cl-] ratio in Hartmann's solution (1.18:1) than in saline (1:1) and to the hyperchloraemia caused by saline.

Long-term combined treatment with thiazide and potassium citrate in nephrolithiasis does not lead to hypokalemia or hypochloremic metabolic alkalosis

Potassium citrate is commonly used in combination with a thiazide diuretic in the medical management of recurrent hypercalciuric nephrolithiasis. However, concerns have been raised that administration of this nonchloride potassium alkali with a kaliuretic and natriuretic agent such as thiazide may not be efficacious in correcting or preventing hypokalemia, and may produce hypochloremic metabolic alkalosis. This retrospective analysis was conducted to determine if these two potential complications are encountered in patients on long-term potassium citrate and thiazide therapy. Data were collected on 95 patients who had been on combination therapy for at least 4 months from the stone clinics of the University of Texas Southwestern Medical Center, Duke University Medical Center, and Ochsner Clinic. Mean serum potassium concentration remained within normal limits without a significant decrease during combined therapy. Serum chloride was significantly lower from pretreatment but by only 1 mEq/L and remained within normal limits throughout treatment. There was a small increase in serum bicarbonate concentration compared to the baseline level of less than 1 mEq/L at 8 to 12 and 18 to 24 months, but not at other treatment periods. Co-administration of potassium citrate did not induce hypokalemia or hypochloremic metabolic alkalosis in our thiazide-treated patient population.

(Ab)normal saline and physiological Hartmann's solution: a randomized double-blind crossover study

In this double-blind crossover study, the effects of bolus infusions of 0.9% saline (NaCl) and Hartmann's solution on serum albumin, haematocrit and serum and urinary biochemistry were compared in healthy subjects. Nine young adult male volunteers received 2-litre intravenous infusions of 0.9% saline and Hartmann's solution on separate occasions, in random order, each over 1h. Body weight, haematocrit and serum biochemistry were measured pre-infusion and at 1h intervals for 6h. Biochemical analysis was performed on pooled post-infusion urine. Blood and plasma volume expansion, estimated by dilutional effects on haematocrit and serum albumin, were greater and more sustained after saline than after Hartmann's solution (P&amp;lt;0.01). At 6h, body weight measurements suggested that 56% of the infused saline was retained, in contrast with only 30% of the Hartmann's solution. Subjects voided more urine (median: 1000 compared with 450ml) of higher sodium content (median: 122 compared with 73mmol) after Hartmann's than after saline (both P = 0.049), despite the greater sodium content of the latter. The time to first micturition was less after Hartmann's than after saline (median: 70 compared with 185min; P = 0.008). There were no significant differences between the effects of the two solutions on serum sodium, potassium, urea or osmolality. After saline, all subjects developed hyperchloraemia (&amp;gt;105mmol/l), which was sustained for &amp;gt;6h, while serum chloride concentrations remained normal after Hartmann's (P&amp;lt;0.001 for difference between infusions). Serum bicarbonate concentration was significantly lower after saline than after Hartmann's (P = 0.008). Thus excretion of both water and sodium is slower after a 2-litre intravenous bolus of 0.9% saline than after Hartmann's solution, due possibly to the more physiological [Na+]/[Cl-] ratio in Hartmann's solution (1.18:1) than in saline (1:1) and to the hyperchloraemia caused by saline.