Ondansetron attenuates the decrease in blood pressure due to spinal anesthesia in the elderly: a double blind, placebo-controlled study.

BACKGROUND: Ondansetron was effectively used to prevent spinal anesthesia-induced hypotension in the general population and women anesthetised for cesarean section. The aim of this study was to test the hypothesis that blocking type 3 serotonin receptors with intravenous ondansetron administration reduces hypotension and bradycardia induced by spinal anesthesia in elderly patients. METHODS: Fifty-three patients participated in the study with 26 in the ondansetron group (received 8 mg intravenous ondansetron) and 27 in the placebo group (received 0.9% NaCl solution). The heart rate and arterial blood pressure were measured every 5 minutes after spinal anaesthesia, which was performed with 2.5 to 3 mL of 0.5% hyperbaric bupivacaine solution. RESULTS: Decreases in both the heart rate and mean systolic, as well as diastolic, arterial pressure compared to the baseline values were noted in both groups. The minimum diastolic and mean blood pressure values obtained over a 20-minute observation period were significantly higher in the ondansetron group. There were no significant differences in the systolic blood pressure and heart rate values between the groups. CONCLUSION: Administration of intravenous ondansetron prior to spinal anesthesia in geriatric patients attenuates the drop in the diastolic and mean arterial pressure without substantially affecting the systolic blood pressure.

Structure of poly(acrylic acid) in electrolyte solutions determined from simulations and viscosity measurements.

In this work, the structure of poly(acrylic acid) (PAA) molecules in electrolyte solutions obtained from molecular dynamic simulations was compared with experimental data derived from dynamic light scattering (PCS), dynamic viscosity, and electrophoretic measurements. Simulations and measurements were carried out for polymer having a molecular weight of 12 kD for various ionic strengths of the supporting electrolyte (NaCl). The effect of the ionization degree of the polymer, regulated by the change in the pH of the solution in the range 4-9 units, was also studied systematically. It was predicted from theoretical simulations that, for low electrolyte concentration (10(-3) M) and pH = 9 (full nominal ionization of PAA), the molecule assumed the shape of a flexible rod having the effective length L(ef) = 21 nm, compared to the contour length L(ext) = 41 nm predicted for a fully extended polymer chain. For an electrolyte concentration of 0.15 M, it was predicted that L(ef) = 10.5 nm. For a lower ionization degree, a significant folding of the molecule was predicted, which assumed the shape of a sphere having the radius of 2 nm. These theoretical predictions were compared with PCS experimental measurements of the diffusion coefficient of the molecule, which allowed one to calculate its hydrodynamic radius R(H). It was found that R(H) varied between 6.6 nm for low ionic strength (pH = 9) and 5.8 nm for higher ionic strength (pH = 4). The R(H) values for pH = 9 were in a good agreement with theoretical predictions of particle shape, approximated by prolate spheroids, bent to various forms. On the other hand, a significant deviation from the theoretical shape predictions occurring at pH = 4 was interpreted in terms of the chain hydration effect neglected in simulations. To obtain additional shape information, the dynamic viscosity of polyelectrolyte solutions was measured using a capillary viscometer. It was found that, after considering the correction for hydration, the experimental results were in a good agreement with the Brenner's viscosity theory for prolate spheroid suspensions. The effective lengths derived from viscosity measurements using this theory were in good agreement with values predicted from the molecular dynamic simulations.

Comparison of the effect of perindopril and acebutolol on cerebral hemodynamics in hypertensive patients.

PURPOSE: The aim of the study was to compare effect of perindopril (4 mg once a day) versus acebutolol (400 mg once a day) on cerebral hemodynamics in hypertensive patients. METHODS: Thirty untreated patients with mild-to-moderate hypertension were studied. Drug influences on Doppler-derived parameters from the cerebral blood flow (CBF) velocity wave form were evaluated in a randomized, double blind, cross-over, placebo controlled study. The mean CBF velocity, pulsatility index (PI), cerebrovascular resistance and index of CBF were calculated from concomitant transcranial Doppler measurements and systemic blood pressure. RESULTS: Acebutolol and perindopril significantly decreased systolic, diastolic and mean blood pressure in relation to placebo. The mean value of CBF velocity increased to a comparable level after both drugs (54.9 +/- 9.1 cm/s on placebo vs 62.8 +/- 14.5 cm/s on perindopril p<0.01 and 61.4 +/- 9.2 cm/s on acebutolol, p<0.01). Also, the cerebrovascular resistance index decreased similarly after both drugs (2.26 +/- 0.35 on placebo vs 1.68 +/- 0.42 on perindopril p<0.01 and 1.7 +/- 0.36 on acebutolol p<0.01). The calculated CBF index increased significantly after each drug (25.23 +/- 7.99 on placebo vs 33.98 +/- 11.23 p<0.01 on perindopril and 30.90 +/- 8.04 on acebutolol p<0.01). However, perindopril augmented the CBF index more effectively than acebutolol (p<0.05). CONCLUSIONS: Among patients with mild-to-moderate hypertension both acebutolol and perindopril beneficially decreased cerebrovascular resistance and increased the CBF index in comparison with placebo. The increase of CBF index was greater after perindopril than acebutolol, which suggests a more significant improvement in cerebral perfusion by perindopril. The non-invasive transcranial Doppler ultrasonography method of CBF velocity measurement may contribute to choosing optimal antihypertensive therapies and to monitor their effect.

[Evaluation of the antihypertensive efficacy and safety of using sustained release verapamil in elderly subjects using ambulatory blood pressure monitoring]. / Ocena skutecznosci hipotensyjnej oraz bezpieczenstwa stosowania werapamilu o przedluzonym dzialaniu u osób w wieku podeszlym przy uzyciu ambulatoryjnego monitorowania cisnienia krwi.

OBJECTIVE: Calcium antagonists are commonly used drugs in the treatment of hypertension in elderly patients. One of the drugs of this group is verapamil. Especially its slow release formula is convenient for use in elderly patients (drug is given once daily). The aim of our study was to evaluate the antihypertensive efficacy of 240 mg slow release verapamil given once daily in elderly hypertensives using ambulatory blood pressure monitoring (ABPM). We also evaluated the safety of this slow release formula using trough to peak ratio. DESIGN AND METHODS: Twenty hypertensives of mean age 67.5 +/- 5.3 were enrolled into the study. Our study was performed using double-blind, placebo-controlled cross-over study design. After a 2-week wash-out period 24-hour ABPM was performed for the first time and then twice: after 2 weeks of placebo or 240 verapamil slow-release and after 2 weeks of verapamil or placebo treatment. The readings prior to and after the treatment were taken using the same procedure. Blood pressure measurements were recorded every 15 minutes between 7.00 and 23.00 and every 30 minutes between 23.00 and 7.00. RESULTS: Verapamil treatment statistically significantly reduced (p < 0.05) mean 24 hour systolic blood pressure from 148.88 +/- 7.56 mmHg to 132.24 +/- 6.13 mmHg and diastolic respectively from 96.68 +/- 6.05 to 83.04 +/- 5.40 mmHg. Heart rate decreased from 77.16 +/- 3.84 BPM to 68.88 +/- 4.41 BPM. Placebo-corrected trough to peak ratio was 70% for systolic blood pressure.

[Hypotensive effects of mononitrates (IS-5-MN) in light of 24-hour blood pressure monitoring]. / Hipotensyjne efekty mononitratów (IS-5-MN) w swietle metody 24-godzinnego monitorowania cisnienia krwi.

Our study was aimed to evaluate the hypotensive effects of a single dose of 100 mg IS-5-MN (Mack) using ambulatory blood pressure monitoring (ABPM). We have enrolled into the study 50 patients. Twenty-one of them were hypertensive (WHO-class I and II) and twenty nine were normotensive. The mean age of the patients was 52.88 +/- 12 years. ABPM was performed during 48 hours. After first 24 hours without any hypotensive drugs the IS-5-MN or placebo was given in double blind study. The readings in the second 24 hours were taken in the same procedure as in the first 24 hours i.e. every twenty minutes between 7.00 and 23.00 every half an hour between 23.00 and 7.00. Mean hourly systolic (SBP) and diastolic (DBP) blood pressures of the first day (without any treatment) and 2nd day (IS-5-MN or placebo) were compared in four group of patients:1. Hypertensives receiving placebo, 2. Hypertensives receiving IS-5-MN, 3. Normotensives receiving placebo and 4. Normotensives receiving IS-5-MN. Only in the fourth group of patients mean hourly blood pressures from the day 2 were significantly lower than from the day I. First hypotensive effects for SBP as well as for DBP were observed four hour after IS-5-MN was given. These effects last about 8 hours. These data confirm the hypotensive effects of mononitrates in normotensive patients.