Papers by Antonios Tzamaloukas
Cureus, 2016
Disturbances in tonicity (effective osmolarity) are the major clinical disorders affecting cell v... more Disturbances in tonicity (effective osmolarity) are the major clinical disorders affecting cell volume. Cell shrinking secondary to hypertonicity causes severe clinical manifestations and even death. Quantitative management of hypertonic disorders is based on formulas computing the volume of hypotonic fluids required to correct a given level of hypertonicity. These formulas have limitations. The major limitation of the predictive formulas is that they represent closed system calculations and have been tested in anuric animals. Consequently, the formulas do not account for ongoing fluid losses during development or treatment of the hypertonic disorders. In addition, early comparisons of serum osmolality changes predicted by these formulas and observed in animals infused with hypertonic solutions clearly demonstrated that hypertonicity creates new intracellular solutes causing rises in serum osmolality higher than those predicted by the formulas. The mechanisms and types of intracellular solutes generated by hypertonicity and the effects of the solutes have been studied extensively in recent times. The solutes accumulated intracellularly in hypertonic states have potentially major adverse effects on the outcomes of treatment of these states. When hypertonicity was produced by the infusion of hypertonic sodium chloride solutions, the predicted and observed changes in serum sodium concentration were equal. This finding justifies the use of the predictive formulas in the management of hypernatremic states.
Advances in Peritoneal Dialysis Conference on Peritoneal Dialysis, 2009
It is not established whether hospitalizations are more frequent or longer in patients on periton... more It is not established whether hospitalizations are more frequent or longer in patients on peritoneal dialysis (PD) or chronic in-center hemodialysis (HD). Comorbidity is a major factor affecting the comparison of hospitalizations. To account for comorbidity, we compared hospitalizations between the PD and HD periods in 16 patients, 8 of whom were treated by PD first (group A), and 8, by HD first (group B). In group A, causes of renal failure were diabetes (n = 3), primary renal disease (n = 2), systemic disease (n = 2), and hereditary nephropathy (n = 1). Age at onset of PD was 53 +/- 11 years; duration of PD, 31 +/- 17 months; and duration of HD, 40 +/- 33 months. This group had 52 hospitalizations in the PD period and 80 hospitalizations in the HD period. Hospitalization rate (n/ patient-year) was 2.5 +/- 2.0 during PD and 3.0 +/- 3.0 during HD (nonsignificant), and duration of hospitalization (days/patient-year) was 19.6 +/- 15.5 during PD and 21.9 +/- 17.7 during HD (nonsignificant). The three most common causes of hospitalization were peritonitis (27%), other infections (21%), and cardiovascular disease (14%) in the PD period, and HD access problems (35%), infections (16%), and cardiovascular disease (12%) in the HD period. In group B, causes of renal failure were diabetes (n = 4), primary renal disease (n = 3), and hypertension (n = 1). Age at onset of HD was 56 +/- 10 years; duration of HD, 41 +/- 19 months; and duration of PD, 60 +/- 24 months. This group had 82 hospitalizations in the HD period and 76 hospitalizations in the PD period. Hospitalization rate was 3.0 +/- 2.4 during HD and 1.9 +/- 2.8 during PD (nonsignificant), and duration of hospitalization was 17.3 +/- 25.1 during HD and 12.7 +/- 21.3 during PD (nonsignificant). The three most common causes of hospitalization were HD access problems (40%), cardiovascular disease (19%), and infections (12%) in the HD period, and other infections (36%), cardiovascular disease (19%), and peritonitis (21%) in the PD period. In patients changing dialysis modalities, rate and duration of hospitalizations did not vary between HD and PD. The causes of hospitalization were similar in the HD and PD periods regardless of which modality was applied first.
International Urology and Nephrology, Jan 10, 2009
Background Estimation of the glomerular filtration rate (GFR) is required in the assessment of pa... more Background Estimation of the glomerular filtration rate (GFR) is required in the assessment of patients with chronic kidney disease (CKD) in order to provide information regarding the functional status of the kidneys. Current guidelines advocate the use of prediction equations, such as the Cockcroft-Gault (CG) formula and the Modification of Diet in Renal Disease (MDRD) study-derived equations, over clearance of endogenous creatinine (Ccr) in achieving this aim. We were interested in knowing the accuracy of these equations in predicting the GFR in adult Nigerians with CKD. Methods We conducted a review of records of patients who were evaluated for CKD at the Nephrology Clinic of the Jos University Teaching Hospital between 2001 and 2003. We compared the CG and MDRD equations against the Ccr in predicting the GFR in 130 patients (88 males and 42 females) with CKD.
International Urology and Nephrology, Mar 6, 2009
Background The incidence of chronic kidney disease (CKD) is increasing, with major health and eco... more Background The incidence of chronic kidney disease (CKD) is increasing, with major health and economic implications. World Kidney Day was established to increase the general public's awareness of CKD. The purpose of this report was to document the selfawareness of CKD by nephrologists practicing in one country, Nigeria. Methods Self-administered questionnaires addressing self-awareness about CKD were distributed to nephrologists attending a meeting of the Nigerian Association of Nephrology. Results Twenty-eight (35.4%) of the respondents admitted to being at risk for CKD; 93.7% reported having urinalysis done in the past, but only 50.6% had done it within the last 12 months. Similarly, 74.7% had at least had a serum creatinine measurement. Only 12.7% had ever had their glomerular filtration rate (GFR) estimated. Conclusion Self-screening for CKD among Nigerian nephrologists is suboptimal. This self-neglect may translate into poor CKD screening practices for their patients.
Peritoneal dialysis international: journal of the International Society for Peritoneal Dialysis
Mineral and Electrolyte Metabolism
This communication contains a model describing osmotic phenomena that result from an osmotic dist... more This communication contains a model describing osmotic phenomena that result from an osmotic disturbance (gain or loss of non-isotonic solutions from the extracellular compartment), if cells function as perfect osmometers. This model (a) predicts the changes in extracellular water and in solute concentration, if the magnitude of the disturbance is known; (b) computes the amount of a solution of a given osmolality necessary to create a desired change in extracellular water; (c) estimates, by osmometric calculations, initial extracellular and total body water; (d) estimates the 'new' solute that is created by anuria and by dilution of extracellular solute controlled by hormonal feedback. Anuria and extracellular expansion are experimental conditions usually accompanying the osmotic disturbance. The model is, therefore, suitable for precise in vivo studies of osmotic disturbances.
Canadian Medical Association journal
Mineral and Electrolyte Metabolism
To test the osmotic function of body tissues in hypertonic extracellular (ECF) expansion in vivo,... more To test the osmotic function of body tissues in hypertonic extracellular (ECF) expansion in vivo, we studied 20 anuric dogs either infused (infusion solution was 0.85 M saline for group A, 1.6 M mannitol for group B and isotonic saline for group C), or not infused with any solution (group D). We compared the observed ECF volume increase (radiosulfate, or cold sodium and chloride space changes), final osmolality, and body water (tritiated water space or apparent sodium volume of distribution) to the values predicted from perfect osmometric function. Observed ECF volume expansion was not different from that predicted (groups A-C). Observed final osmolality and body water were significantly greater than predicted final osmolality (groups A-D) and osmotic volume of distribution (groups A and B), respectively. We then computed 'new' solute generated from anuria (groups A-D) and from dilution of ECF solute controlled by hormonal feedback (groups A-C); this solute was comparable for all four groups. Corrected for this solute observed final osmolality and osmotic volume of distribution were not different from the predicted final osmolality (groups A-D) and measured body water (groups A and B), respectively. It is concluded that in hypertonic ECF expansion, perfect osmometric function predicts accurately the degree of ECF expansion and, if appropriate corrections are made for experimental conditions other than hypertonicity, final osmolality and body water.
Journal of nephrology nursing
Revista ClÃnica Española
Western Journal of Medicine
Mineral and Electrolyte Metabolism
Based on mathematical analysis, a method computing deviations from normal in body weight, water a... more Based on mathematical analysis, a method computing deviations from normal in body weight, water and sodium, and requiring only presenting body weight and hyperglycemic and euglycemic plasma glucose and sodium concentrations in anuria was developed. Data from 18 hyperglycemic episodes (12 anuric patients) treated with insulin alone were analyzed by this method and were compared to clinical estimates. When normal body water and extracellular volume were assumed to be 0.579 and 0.213 of dry weight, respectively, deviations of presenting weight from dry weight (in kg) were as follows (x = clinical estimate, y = new method estimate): x: -2.5 to +17.2 (+4.6 +/- 5.1, SD); y: -4.1 to +16.7 (+4.2 +/- 5.4, NS); y = -0.4 + 1.0008x, r = 0.96 (p less than 0.01). Similar comparisons were obtained for deviation of body sodium from normal and for euglycemic extracellular volume. Estimates by the two methods agreed when normal body water was assumed to vary between 0.525 and 0.625 of dry weight and when normal extracellular volume was assumed to vary between 0.31 and 0.40 of normal body water.
Western Journal of Medicine
Mineral and Electrolyte Metabolism
The magnitude of the osmotic fluid shifts between extracellular and intracellular compartments an... more The magnitude of the osmotic fluid shifts between extracellular and intracellular compartments and the changes in solute concentration that follow a change in extracellular solute are determined by the following factors: (1) the rate constant of total body osmotic fluid transfer, (2) the change in the amount of solute per liter of initial extracellular volume, (3) the initial ratio of intracellular to extracellular volume, which is usually determined by the state of extracellular volume (for the same change in the amount of solute per liter of initial extracellular volume, the changes in both extracellular volume and osmolality are greater in edematous than nonedematous states) and (4) the initial osmolality of body fluids (comparatively, the lower the initial osmolality, the larger the osmotic fluid shifts will be). However, the magnitude of the change in osmolality will be the same regardless of initial osmolality, if the other determinants are the same. If the determining factors are known, formulae applied in clinical medicine to predict the changes in solute concentration are theoretically sound. The initial intracellular to extracellular volume ratio characterizes the state of body fluids and can be computed from the changes in solute concentration provided that osmotic equilibrium exists between intracellular and extracellular compartments before and after the osmotic disturbance.
Peritoneal dialysis international: journal of the International Society for Peritoneal Dialysis
Peritoneal dialysis international: journal of the International Society for Peritoneal Dialysis
Peritoneal dialysis international: journal of the International Society for Peritoneal Dialysis
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Papers by Antonios Tzamaloukas