Biomedical subjects

S Ojanen

Publications and source records attributed to S Ojanen.

6 recordsLinked to original sources

PubMed2002

Isolated ultrafiltration affects dynamic vectorcardiographic ischemia monitoring parameters.

AIMS: The present study was undertaken to assess the role of isolated ultrafiltration (UF phase) and hemodialysis with minimal ultrafiltration (HD phase) in changes in parameters reflecting myocardial ischemia: QRS vector difference (QRS-VD), ST change vector magnitude (STC-VM) and ST vector magnitude (ST-VM6) registered by MIDA (myocardial infarction dynamic analysis). PATIENTS AND METHODS: Twelve patients on maintenance hemodialysis were first ultrafiltrated for 2.5 h without dialysis (UF) followed by a 2.5-hour session of hemodialysis with minimal ultrafiltration (HD). Computerized vectorcardiography (VCG) was used for on-line dynamic analysis of ST segment and QRS complex changes. Blood volume (BV) changes were monitored non-invasively and continuously with the CRIT-LINE instrument. Whole-body bioelectric impedance analysis (BIA) was used for extracellular water (ECW) estimation. RESULTS: During the UF phase QRS-VD and STC-VM showed a statistically significant increasing linear trend (time effect for both QRS-VD and STC-VM p < 0.0001, while no changes were noted in ST-VM6; time effect p = 0.986). During the HD phase none of these parameters changed (time effect for QRS-VD p = 0.855, for STC-VM p = 0.275 and for ST-VM6 p = 0.976). During the UF, phase changes in QRS-VD were in close relation to those in ECW. CONCLUSION: Isolated ultrafiltration leads to an increase in the VCG ischemia monitoring parameters QRS-VD and STC-VM. The increase of QRS-VD is related to changes in ECW. Hemodialysis with minimal ultrafiltration has no effect on VCG ischemia monitoring parameters.

Adult↗

PubMed2000

Hemodialysis causes changes in dynamic vectorcardiographic ischemia monitoring parameters.

AIMS: The aim of this study was to establish whether changes in parameters reflecting myocardial ischemia QRS vector difference (QRS-VD), ST change vector magnitude (STC-VM) and ST vector magnitude (ST-VM6) during hemodialysis (HD) registered by MIDA (myocardial infarction dynamic analysis) are related to changes in blood volume (BV), extracellular water (ECW) and blood biochemistry. PATIENTS AND METHODS: Fifteen hemodialysis (HD) patients were studied. Computerized vectorcardiography was used for on-line dynamic analysis of ST segment and QRS complex changes. BV changes were monitored non-invasively and continuously with the CRIT-LINE instrument. Bioelectric impedance analysis (BIA) was used for ECW estimation. Blood samples were taken before and after hemodialysis for hemoglobin (B-Hb), hematocrit (B-Hcr), sodium (P-Na), chloride (P-Cl), magnesium (P-Mg), potassium (P-K), ionized calcium (P-iCa), phosphate (P-Pi) and astrup measurement. RESULTS: During dialysis treatment QRS-VD, ST-VM6 and STC-VM did not change in parallel. According to the linear mixed model, no statistically significant changes were noted in ST-VM6 during dialysis (time effect p = 0.5635). On the other hand, QRS-VD and STC-VM showed a statistically significant linear trend (time effect for QRS-VD p = 0.0001 and for STC-VM p = 0.0004). Changes in both ECW and BV affected the change in QRS-VD and in STC-VM. CONCLUSION: During HD treatment changes in the vectorcardiographic ischemia monitoring parameters QRS-VD and STC-VM are mostly related to ECW and BV changes and may give a false positive impression of myocardial ischemia. The ST-VM6 trend is less markedly influenced by volume changes.

Adult↗

PubMed1999

QRS amplitude and volume changes during hemodialysis.

BACKGROUND: According to several studies the QRS amplitude of the ECG increases during hemodialysis. The detailed background to this phenomenon has not been defined. Two main mechanisms have been suggested: myocardial ischemia and volume changes. New noninvasive technologies make possible a comparison of QRS complex changes synchronously with myocardial ischemia and extracellular water (ECW)/blood volume (BV) changes during hemodialysis. METHODS: In this study hemodialysis-related changes in body weight, biochemical blood variables, BV, ECW, ST segment and QRS complex were analyzed in 15 patients (age 36-76, time on dialysis 0-6 years) undergoing chronic hemodialysis treatment. QRS complex and ST segment changes were measured using a dynamic vectorcardiographic monitoring system. The ECG parameters measured were QRS vector difference (QRS-VD) and ST vector magnitude (ST-VM6). Bioimpedance analysis was used to detect changes in the ECW. Continuous measurement of BV changes was implemented using an on-line optical reflection method based on the reflection of infrared light by erythrocyte membranes. Blood hemoglobin (B-Hb), hematocrit (B-Hcr), plasma sodium (P-Na), chloride (P-Cl), magnesium (P-Mg), potassium (P-K), ionized calcium (P-iCa), phosphate (P-Pi), creatinine (P-Crea) and urea (S-Urea) were monitored. RESULTS: The mean QRS-VD increase during the dialysis session was almost fourfold (372 +/- 300%) from 4.16 +/- 2. 40 to 15.60 +/- 7.0 microVs (p < 0.001). This change was due to a change in amplitude, since the duration of the QRS complex did not alter significantly. The correlation between the changes in QRS-VD and body weight from the start to the end of the dialysis session was moderate and statistically significant (r = -0.55, p < 0.05). The correlation between the changes in QRS-VD and ECW varied from r = -0.67 to -0.97, being statistically significant in all patients (p < 0.001). The correlation between BV and QRS-VD was assessed at one minute intervals during the dialysis and varied from r = -0.22 to -0. 98, being significant in 14 of the 15 patients (p < 0.001). Significant ST segments alterations (ST-VM6 elevation > 100 microV) did not occur during dialysis. Laboratory parameters reflecting volume and osmotic changes during hemodialysis correlated with QRS-VD change: B-Hcr (r = 0.56, p < 0.05), B-Hb (r = 0.63, p < 0.05), P-Na (r = 0.62, p < 0.05) and S-Urea (r = -0.62, p < 0.05). CONCLUSIONS: The increase in QRS complex amplitude during hemodialysis is correlated to reduced ECW. The mechanism involved is most probably augmentation of electrical resistance of the tissues around the heart caused by loss of interstitial fluid.

Adult↗

PubMed1996

Plasma atrial natriuretic peptide, body weight and twenty-four-hour blood pressure monitoring in chronic hemodialysis patients.

In this study we investigated the interactions between volume changes (body weight), plasma atrial natriuretic peptide (pANP) and ambulatory blood pressure (BP) in 10 patients with end-stage renal disease undergoing regular hemodialysis (HD) treatment three times weekly. Most patients retained their diurnal BP variation when their BP was adequately controlled. Interdialytic weight gain was 1.3 +/- 0.2 kg and the day-time systolic BP increased 12.5 +/- 4.8 mm Hg on the second interdialytic day. pANP did not correlate (r = -0.07, p = 0.85) with this BP elevation, but there was a fairly strong positive correlation (r = 0.61, p = 0.06) between interdialytic weight gain and systolic BP. The mean pANP level decreased from 149.7 +/- 18.2 to 117 +/- 0.1 ng/l during HD and continued its decrease to 83 +/- 12.2 ng/l at 20 h after an HD session. The total decrease from 149.7 +/- 18.2 to 83 +/- 12.2 ng/l was statistically significant (p = 0.001). Since the lowest pANP value was found 20 h after completion of the dialysis session, body weight is a more reliable indicator of volume reduction during HD than pANP. The results indicate that in HD patients weight gain between two dialysis sessions increases the day-time systolic BP but not the diastolic BP. Diurnal BP variation is maintained as long as BP is adequately controlled either by volume control or by drug treatment.

Adult↗

PubMed1994

Pharmacokinetics of clodronate in renal failure.

The pharmacokinetic parameters describing the fate of one intravenous clodronate (disodium dichloromethane diphosphonate) dose was studied in 24 normal subjects and in 24 patients with different degrees of renal insufficiency. The aim of the study was to derive data for adjustment of dosage in relation to renal function. Disodium clodronate in serum and urine samples was analyzed by capillary gas chromatography with mass-selective detection. The renal clearance (CLR) of clodronate was highly dependent on renal function and declined successively with declining glomerular filtration rate (GFR). Plasma clearance (CLP) declined, too, but to a lesser degree than CLR. The impairment of renal function resulted in decreased cumulative urinary elimination of clodronate and increased total areas under the serum concentration-time curve (AUC0-infinity). Hence, as the renal elimination of clodronate diminishes with decreasing GFR, there is a related retention of the substance. As a result of the present study, the following dosages are recommended: creatinine clearance (CLCr) from 50 to 80 ml/minute, 75-100% of normal dose; CLCr 12-50 ml/minute, 50-75% of normal dose; and ClCr < 12 ml/minute, 50% of normal dose. The results must be interpreted with caution in patients with malignancy and severe skeletal disease, in whom the nonrenal clearance may vary markedly.

Adult↗

PubMed1978

Immediate-type hypersensitivity to reactive dyes.

Reactive dyes have gained extensive use in recent years. This paper reports four cases of immediate-type occupational allergy to these compounds. All the patients had had symptoms of asthma and allergic rhinitis, and had been weighing dyes for a minimum of 2 years. The skin prick tests were positive, and nasal and bronchial provocation challenges also produced positive immediate reactions. A high serum titre of specific IgE could be demonstrated for at least one dyd by the radioallergosorbent test. The identification of specific IgE shows that the mechanism of the hypersensitivity is immunological, reactive dyes acting probably as haptens.

Adult↗