[Pathophysiology of metabolic acidosis in patients with reduced glomerular filtration rate according to Stewart-Fencl theory]

AIM

Metabolic acidosis is a regular sign of renal insufficiency. Conventional assessment of acid-base balance using Henderson-Hasselbalch equation does not make identification of the cause of metabolic disorders possible as the serum HCO3- concentration might only reflect changes to the overall plasma ion spectrum. Therefore, we used the Stewart-Fencl approach that is based on a more detailed physical and chemical analysis and that showed that changes to serum HCO3- concentration are closely related to parameters not usually monitored in connection to acid-base balance. PATIENT GROUP AND METHODOLOGY: We performed a single measurement of arterial or capillary blood pH and pCO2 in 69 non-dialysed patients with glomerular filtration rate ranging from 0.04 to 0.88 ml/s/1.73 m2 according to MDRD, standard calculation of serum HCO3- concentration using Henderson-Hasselbalch equation was carried out, and serum albumin and ion concentrations (Na+, K+, Cl, Pi) plus creatinine and urea concentrations were determined from venous blood.

RESULTS

Metabolic acidosis was present in 47 patients ([S-HCO3-] < 22 mmol/l) with the mean [S-HCO3-] value of 19.6 mmol/l for the entire group. We proved a statistically significant correlation between [S-HCO3-] and [SID] (p < 0.001), and between [S-HCO3-] and the individual [SID] determining factors: [Na+-Cl-], [UA- ], [Pi-], [K+] (p < 0.01).

CONCLUSION

Reduction in [S-HCO3-] in non-dialysed patients with reduced glomerular filtration is predominantly associated with a decrease in [Na+-Cl-] difference, the quantitative contribution of which to metabolic acidosis is more significant than the strong acids retention. In addition to [S-Cl-] increase, [S-Na+] reduction too has a major role in reducing the [Na+-Cl-] difference.

[Bacterial infection and its relation to the genesis and course of varicose hemorrhage]

Acute hemorrhage from esophageal varices due to portal hypertension is a frequent and serious complication of liver cirrhosis. Bacterial infection may be one of the factors influencing such hemorrhage. Endotoxins may increase portal tension and at the same time result in primary hemostasis disorder, thus becoming one of the causes of hemorrhage. The authors of the paper compared the incidence of bacterial infection in 53 patients with varicose hemorrhage due to portal hypertension with 62 patients with liver cirrhosis and portal hypertension without varicose hemorrhage. At least one pathogen was found in considerable 61.1% of the total of patients in the liver cirrhosis group, while the difference between the two groups was but insignificant. No statistically significant difference was found between the group of patients with hemorrhage and those without hemorrhage in terms of presence of bacterial infection in hemoculture, urine, throat, faeces and ascites, nor was there a difference in the etiology of the G+ bacteria, G- bacteria or fungi and yeast infectious agents in the hemoculture, urine, throat, faeces and ascites in either of the groups. No statistically significant difference was found in comparing the patients with a recurrence of hemorrhage (or with mortality) and with infection with those without recurrence of hemorrhage. Bacterial infection was more often found in patients with a recurrence of hemorrhage (75%) as compared with those without any recurrence (52%), and also in patients who died bacterial infection was proven more often than in those who survived (61.9% vs. 58.1%, respectively). There was no difference in morbidity or recurrence of hemorrhage between the patients treated with norfloxacin and ampicilin/sulbactam. No statistically significant difference was recorded between the 1st and 5th day in terms of decrease in bacterial infection. A significant difference was found in the urine etiological agent, where a significant increase in the share of fungal and yeast urine infection (p = 0.011) was recorded after the application of the therapy, as well as a drop in urine infection caused by the G- bacterial agent (p = 0.057).

[Risky medication and contrast media-induced nephropathy in patients with diabetes and hypertension]

Contrast media-induced nephropathy (CMIN) is accompanied by high morbidity, lengthy hospitalization, and a higher mortality rate. In proportion to the rising number of diagnostic and interventional radiological procedures, the prevalence of this complication is also rising The study briefly tackles the currently known pathophysiological mechanisms that lead to CMIN and deals with various risk factors which increase the probability of development of contrast nephropathy. Among these factors are, in the first place, diabetes mellitus, a pre-existing renal illness and hypertension. In addition, the risk of developing CMIN significantly increases in patients on risky medication. In our study, this medication was a combination of ACE-inhibitors (ACEI) and furosemide. Even though none of the patients met the criteria defined for CMIN, radiocontrast examination showed a significant statistical decline in glomerular filtration (GFR) and a rise in proteinuria (PU) in the sub-group which used this combination of medication. The risk level of this medication especially in patients with pre-existing nephropathy is also underlined by the suggested dependency of the relative rise in the serum levels of creatinine in terms of its input value. It is necessary, as early as the radiocontrast examination is being done, to bare in mind the possibility of CMIN occurring and avoid it also through the modification of the risk factors which can be influenced, e.g. elimination of risky medication and in indicated cases, taking preventive measures.