Biomedical subjects

R Tkácová

Publications and source records attributed to R Tkácová.

At least 19 recordsLinked to original sources

PubMed2002

Cardiovascular implications of sleep apnea in patients with congestive heart failure.

Recent epidemiologic studies indicate that approximately 40 to 50% of stable patients with congestive heart failure (CHF) suffer from either obstructive sleep apnea (SA) or Cheyne-Stokes respiration with central SA. In either type of sleep apnea, several mechanisms contribute to significant mechanical and adrenergic stresses upon the failing myocardium. These include hypoxemia, reductions in intrathoracic pressure, rises in systemic arterial pressure, increases in left ventricular afterload, and arousals from sleep worsening the sleep architecture. Consequently, sympathetic activation and parasympathetic withdrawal are the hallmark of sleep-related sleeping disorders that contribute to the progression of heart failure and may adversely affect its prognosis. On the other hand, recent studies indicate that successful treatment of either type of SA with continuous positive airway pressure in patients with CHF results in objective and subjective improvement in the severity of heart failure increases in left ventricular ejection fraction, and reductions in sympathetic nervous system activity. Therefore, the early diagnosis and specific treatment of either obstructive or central SA in patients with CHF is highly warranted.

Heart Failure↗

PubMed1997

[Disorders of heart rhythm and ECG changes in experimental apneic states].

BACKGROUND: Apnoeic events are often accompanied by various disturbances in electric cardiac activity, the character and development as well as mechanism of which remain broadly unknown suggesting both direct metabolic defects as well as neurogenous autonomic influences. METHODS: Changes in ECG and heart rate induced by repeated short-lasting inhalation of hypoxic poikilocapnic mixtures (100% N2 and/or 0.5-1% CO2 or 6% CO2 in N2) were analyzed in 17 spontaneously breathing cats anaesthetized with sodium pentobarbitone (40 mg.kg-1i.p.). RESULTS: N2 inhalation evokes hypoxaemic hyperventilation progressing into apnoea and bradycardia with secondary low-level atrioventricular conduction block and ischaemic changes in ECG. Contrary to this reversible respiratory failure, hypoxaemic hypercapnic hyperventilation and apnoea evoked by inhalation of 6% CO2 in N2 or 100% CO2 were accompanied by very marked additional effects of hypercapnia and acidosis. They appeared earlier and were more severe (high-level AV conduction block and premature contractions) suggesting direct myocardial alteration due to acidosis. CONCLUSIONS: The results provide experimental data for better understanding the dynamics, intensity and development of dysrhythmias and ECG changes occurring in two different types of cardiorespiratory failure in animal experiments as well as in central and obstructive types of sleep apnoea and other apnoeic events in humans. (Fig. 3, Ref. 27.)

Animals↗

PubMed1995

[Pulmonary function in patients with chronic kidney failure].

Changes in the function of the respiratory system are among the frequent complications of chronic renal failure whereby their clinical impact is manifested above all in critically ill patients. A typical finding during ventilometric examinations is the limited airflow in the distal airways, and even the clinical picture of obstructive ventilation disorder is not rare. A reduced diffusion capacity of the lungs for CO was found in uraemic patients in long-term dialyzation program as well as after successful renal transplantation. The function of respiratory muscles is characterized by a reduction of the maximal inspiration and expiration pressure. Chronic haemodialyzed patients have a reduced ventilation response to CO2 which may render weaning from the ventilator difficult. In patients with chronic renal failure a high prevalence of the sleep apnoea syndrome was described. During haemodialysis we can observe alveolar hypoventilation, after its termination we find higher values of dynamic pulmonary volumes, as compared with values before dialysis. Chronic ambulatory peritoneal dialysis creates a prolonged state of iatrogenic ascites and this leads to a reduced residual functional capacity of the lungs, while the configuration of the diaphragm is altered. The author reviews in the submitted paper contemporary findings on the pathogenesis and clinical characteristics of pulmonary functions in patients with chronic renal failure.

Humans↗

PubMed1994

[Factors affecting serum lipid levels in patients with type 2 diabetes mellitus].

Serum lipid concentrations were assessed in 147 type 2 diabetics. The patients were divided into different sub-groups in order to follow up different factors which could have an impact on serum lipids. The mean total cholesterol concentrations were significantly higher in diabetic women as compared with men. The authors did not reveal significant differences in lipid concentrations between obese and non-obese diabetics. Hypertensive diabetics had higher mean total cholesterol levels and LDL-cholesterol levels, as compared with diabetic patients without hypertension. Patients using oral antidiabetics had significantly higher mean triglyceride levels and lower HDL-cholesterol levels, as compared with insulin-treated diabetics. In a multiple stepwise regression analysis correlated triglycerides with three independent variables: total cholesterol, diastolic blood pressure and inversely with HDL-cholesterol. On the other hand, total cholesterol correlated significantly with triglycerides, HDL-cholesterol and proteinuria/day. To sum up, it may be stated, that the results of the present investigation are consistent with Reaven's concept of the syndrome X, however the cholesterol concentration is affected also by the proteinuria.

Cholesterol↗

PubMed1993

Type IV renal tubular acidosis associated with Alport's syndrome.

A case of hereditary nephritis with mild reduction of renal function associated with renal tubular acidosis type IV is described. The patient was admitted with life-threatening hyperkalaemia. To our knowledge, type IV renal tubular acidosis has not been reported previously in association with Alport's syndrome in an adult patient.

Acidosis, Renal Tubular↗

PubMed1993

[Computer evaluation of respiratory changes during acute hypoxia in an experimental model].

Experiences are presented concerning the use of a computer system in analyzing the dynamics of respiratory changes during reversible respiratory failure induced by inhalation of nitrogen in anesthetized cats. The main focus is on semiautomatic evaluation of the air flow signal during experimentally induced hypoxia in model experiment. On the basis of experience with computer aided evaluation of respiratory changes in over 40 animals and regarding the analysis of actual data obtained from 29 hypoxic episodes leading to reversible respiratory failure in 9 cats, advantages and pitfalls of evaluating respiration parameters by the breath-by-breath method are highlighted. Besides demonstrating the applied computer processing of data, the paper evaluates the most important of the 30 respiratory parameters studied, i.e. tidal volume (VT), minute ventilation (VE), inspiratory time (TI), and the ratios VI/TI and TI/TTOT. The results allow to quantify well the dynamics of development of changes of the respiratory model particularly during the first phase of acute hypoxic hypoxia. (Tab. 1, Fig. 5, Ref. 21).

Acute Disease↗

PubMed1993

[Atrial natriuretic factor as a marker of clinical severity in cardiac failure].

The authors examined plasma levels of the atrial natriuretic factor (ANF) in 26 patients with manifestations of cardiac failure. The ANF levels were high as compared with reference values (21 +/- 16.7 fmol/ml vs. 4.9 +/- 2.1 fmol/ml) and different in relation to individual functional NYHA classes, i.e. the lowest ones were in the second and the highest ones in the fourth class. Concurrently the authors revealed a statistically significant negative exponential correlation between plasma ANF levels and the left ventricular ejection fraction (r = 0.550, p < 0.01) and a bordeline correlation between ANF and the stroke volume (r = -0.45, p = 0.05). The results indicate that the plasma ANF level is a good indicator of severity of cardiac weakness and can be used in clinical work as a prognostic indicator in patients with heart failure.

Adult↗

PubMed1993

Spirometric alterations in patients with reduced renal function.

Spirometric parameters were measured in 49 patients with reduced renal function. The patients were divided according to their glomerular filtration rate (GFR) into two groups: (A) GFR < 0.2 ml s-1-end stage renal failure; (B) GFR > or = 0.2 ml s-1. FEV1 and FEF25-75 were significantly lower in the end-stage renal failure group of patients. 80% of the patients with GFR < 0.2 ml s-1 and 31% of the patients with GFR > or = 0.2 ml s-1 had spirometric evidence of small airways dysfunction. In multiple stepwise regression analysis with ventilatory parameters as dependent variables and renal function, total protein, urea, creatinine, sodium, and hemoglobin levels, proteinuria, diuresis, and history of left ventricular failure as independent variables only GFR and total protein correlated significantly with FEV1 and FEF25. In conclusion, our study demonstrates that impairment of spirometric function in patients with renal insufficiency is continual, with reduction of GFR, and thus small airways dysfunction may be expected not only in patients with end-stage renal failure, but also in those with moderate GFR reduction.

Adult↗

PubMed1992

Levels of cardiovascular risk factors in type 2 diabetes mellitus are dependent on the stage of proteinuria.

Levels of cardiovascular risk factors were determined in 75 patients with Type 2 diabetes mellitus. The patients were divided into three groups according to their urinary protein excretion (UPE): (a) normal proteinuria (less than or equal to 70 mg d-1); (b) microproteinuria (70-500 mg d-1); and (c) macroproteinuria (greater than 500 mg d-1). A significant stepwise increase in mean systolic blood pressure, LDL-cholesterol and fibrinogen levels was observed from the first to the third investigated group of patients. Mean apoprotein B levels were significantly increased in the group with macroproteinuria compared to the other two groups. Significant linear correlations were found between UPE and LDL-cholesterol, total cholesterol, apoprotein B, creatinine, systolic blood pressure and diabetes duration. In summary, it is concluded that the levels of some cardiovascular risk factors increase with the stage of proteinuria in Type 2 diabetes mellitus.

Aged↗

PubMed1992

Risk factors for atherosclerosis in female type II diabetic patients with incipient diabetic nephropathy.

Risk factors for atherosclerosis were investigated in a group of 17 female Type II diabetic patients with microalbuminuria-urinary albumin excretion (UAE) in the range of 30-300 mg/day, and in a control group including 15 Type II diabetic females with UAE less than 30 mg/day. Significantly increased mean concentrations of total and LDL-cholesterol were measured in the group with microalbuminuria (p less than 0.05). Also mean levels of some other cardiovascular risk factors (systolic blood pressure, fibrinogen, apolipoprotein B, triglycerides and uric acid) were higher in the group of patients with microalbuminuria, although the differences in comparison to the control group did not reach the level of statistical significance. In the multiple stepwise regression analysis log transformed UAE values correlated significantly with three independent factors--uric acid (p less than 0.01), fibrinogen (p less than 0.05), and systolic blood pressure (p less than 0.05). It is concluded that a slight increase in the levels of a number of cardiovascular risk factors observed in incipient diabetic nephropathy suggests an additive effect favouring atherogenesis.

Albuminuria↗

PubMed1992

[Disorders of lipid metabolism in type 2 diabetics].

The authors investigated the incidence of different disorders of the lipid metabolism and their age dependence in a group of 67 patients with type 2 diabetes hospitalized at the First Medical Clinic in Kosice. Some disorder of the lipid metabolism was recorded in 67% of the patients. The most frequently encountered disorder was hypertriglyceridaemia (21%). Hypercholesterolaemia was recorded in 16%, combined hyperlipidaemia in 18% and hypoalphalipoproteinaemia in 12% of the patients. Patients with diabetic nephropathy had significantly elevated mean triglyceride levels and reduced HDL-cholesterol levels, as compared with patients without nephropathy. In diabetic women a significantly higher incidence of combined hyperlipidaemias was recorded, as compared with men and the mean total cholesterol and triglyceride levels were also significantly higher in women with type 2 diabetes.

Aged↗

PubMed1992

Hematologic changes in type 2 diabetic patients with various localizations of peripheral vascular disease.

Some hematologic parameters have been measured in 80 patients with Type 2 diabetes mellitus. The patients were divided into three groups: (a) proximal (pelvic and femoral) lower limb macroangiopathy; (b) distal (tibial) macroangiopathy; and (c) control group of diabetics without lower limb macroangiopathy. Mean hemoglobin, hematocrit and fibrinogen values were significantly higher in both the proximal and distal macroangiopathy groups in comparison with the controls. On the other hand, mean leucocyte and platelet counts were significantly elevated only in the proximal macroangiopathy group. Significant correlations were observed in univariate and multivariate analyses between blood fibrinogen concentration and pressure indices expressing severity of lower limb macroangiopathy (ankle/thigh, ankle/arm). In summary, increased levels of hematologic parameters contributing to the increase of whole blood viscosity were observed in Type 2 diabetics with arteriosclerosis obliterans. The observed relationship between fibrinogen concentration and severity of arteriosclerosis obliterans could be an evidence in favor for fibrinogen lowering therapy in this pathologic condition.

Arteriosclerosis Obliterans↗

PubMed1991

Reversal of apnoea by aspiration reflex in anaesthetized cats.

Various flow and timing characteristics of breathing as well as electrocorticographic (ECoG) records were analysed in a model of reversible respiratory failure induced by N2 inhalation in 27 anaesthetized cats. During the first minute of respiratory arrest, nasopharyngeal stimulation by an elastic nylon fibre elicited a typical sniff- or gasp-like aspiration reflex (in 88.8% of cases), whilst similar tracheobronchial irritation evoked a weak cough reaction in one third of cases (34.2%). The aspiration reflex could also be evoked in progressive stages of apnoea characterized by very low and even isoelectric ECoG activity immediately before imminent irreversible respiratory failure, and it could interrupt and replace the periodic gasping sometimes occurring during apnoea. The reflex, comprising powerful inspiration efforts, could be evoked during apnoea many times in succession. Repeated aspiration reflexes alone resulted in recovery from hypoxic apnoea with gradual normalization of ECoG and subsequent restitution of spontaneous breathing even more frequently than it occurred in periodic gasping. Successful resuscitation from hypoxic apnoea by the aspiration reflex in cats suggests that nasopharyngeal stimulation can affect the mechanisms underlying the failure and restitution of breathing at least in some forms of apnoea.

Animals↗

PubMed1991

Hypoxic apnoea induced by N2 inhalation can be reversed by the aspiration reflex in anaesthetized cats.

Various cardiorespiratory and electrophysiological parameters were analysed in a model of acute respiratory failure induced by inhalation of pure nitrogen in approximately 150 anaesthetized cats. Initial hyperventilation leading to apnoea was characterized by extreme hypoxaemia, marked bradycardia and flattening of electrocortical (ECoG) activity. Artificial ventilation applied at the stage of marked mydriasis usually spontaneously prevented cardiovascular failure and normalized vital functions. Up to seven successive apnoeic attacks could be induced in the same cat. During the first 30 or 60 s of apnoea, nasopharyngeal stimulation usually elicited a typical gasp-like aspiration reflex, while tracheobronchial stimulation provoked a weak cough only in 28 and 34% of cases for 30- and 60-s apnoea, respectively. The aspiration reflex could be elicited at very low and even isoelectric ECoG activity, and its periodic provocation (without artificial ventilation) resulted, more frequently than did gasping, in recovery from hypoxic apnoea. Arousal and resuscitation induced by the aspiration reflex can provide a useful model to study the mechanisms of reversible respiratory failure and restitution of vital functions.

Administration, Inhalation↗

PubMed1990

Driving and timing components of the breathing pattern during hypoxia in anaesthetized cats.

The effects of acute hypoxic hypoxia elicited by N2 inhalation on the driving and timing components of the breathing pattern were studied in 18 adult anaesthetized cats. Two phases could be distinguished in the ventilatory response to acute hypoxia. During the first phase, mean inspiratory flow (VT/TI) increased exponentially up to 240% of the initial value. During the second phase, VT/TI gradually decreased, reaching the control values in the last preapnoeic breaths during the first exposure and remained higher than normal with earlier respiratory arrest in three repeated N2 inhalations. No significant changes could be observed in the timing component of breathing pattern (TI/TT) in the course of the first hypoxic exposure, and the changes in TI/TT did not exceed 7% in repeated attacks. This suggests that the shortening of both inspiratory and expiratory durations increased the breathing frequency up to 130% of its resting value. Moreover, tachypnoea was preserved until respiratory arrest. Accordingly, it is concluded that the decrease in ventilation with the appearance of apnoea during the second phase of N2 inhalation in anaesthetized cats is not due to a failure of respiratory timing, but to a depression of the driving mechanisms which are responsible for this phenomenon.

Analysis of Variance↗

PubMed1990

[Plasma renin activity, creatinine and uric acid in the serum of patients with essential hypertension].

The authors examined the plasma renin activity (PRA), serum uric acid and creatinine in 53 patients with essential hypertension (EH). They recorded low renin EH in 28%, normorenin EH in 53% and high-renin EH in 19% of the hypertensive patients. Assessment of basal PRA levels does not suffice for the classification of EH because the PRA response after stimulation is not related to its basal values. The authors found significantly higher levels of serum creatinine in low-renin EH. They did not confirm a relationship between PRA and the uric acid serum level in any form of EH.

Adult↗

PubMed1990

[Plasma renin activity and aldosterone in patients with essential hypertension].

The authors examined the plasma renin activity (PRA) in 80 patients and plasma aldosterone (PA) in 27 patients with essential hypertension (EH). They confirmed the significant drop of stimulated PRA with age. The PA levels of hypertonic patients did not change with age and did not change significantly in relation to PRA. In obese hypertonic patients a satisfactory response of PRA to stimulation was lacking, while PA reacted adequately. The PA levels are thus in older age groups as well as in obese subjects much higher, as compared with relatively low PRA levels. In relation to the stage of EH the authors did not find any significant differences of PRA levels.

Adolescent↗

PubMed1989

Influence of acute hypoxia upon brilliant cresyl blue-induced disintegration of erythrocytes in rabbits and cats.

The disintegration of erythrocytes by brilliant cresyl blue was studied in rabbits and cats during two hypoxic periods resulting in apnoea which was followed by artificial ventilation and recovery. The rate of erythrocyte disintegration was measured after 2 hours' incubation in isotonic NaCl or Krebs-Ringer solution plus brilliant cresyl blue (0.5 mmol.l-1). Significant increases of disintegration rates were found in rabbits during recovery in both incubation solutions. Erythrocytes in cats seemed to be more resistant to acute hypoxia, as their disintegration rate rose only in isotonic NaCl solution, and that only transiently. Brilliant cresyl blue--induced erythrocyte disintegration in cats did not differ from the control values during 10 min of spontaneous breathing after the first and the second period of hypoxia in the isotonic NaCl solution, but it was significantly lower in Krebs-Ringer solution. The possible factors influencing the erythrocyte disintegration rate in acute hypoxia are discussed.

Animals↗