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Biomedical subjects

J Toivonen

Publications and source records attributed to J Toivonen.

At least 19 recordsLinked to original sources
PubMed1992

Labetalol attenuates the negative effects of deliberate hypotension induced by isoflurane.

The effect of labetalol on deliberate hypotension was studied in 24 adult patients undergoing middle-ear surgery. Hypotension was induced in Group I (12 patients) with isoflurane 3.0 vol% in inspiratory gas, and in Group II (12 patients) with labetalol 0.5 mg.kg-1 i.v., in addition to isoflurane. The induction time of hypotension was 4.9 +/- 1.0 (s.e.mean) min in Group I, and 1.8 +/- 0.2 min in Group II (P less than 0.01). The mean isoflurane concentration in inspiratory gas for the maintenance of hypotension was 1.4 +/- 0.2 vol% in Group I, and 0.7 +/- 0.1 vol% in Group II (P less than 0.01). There were no differences in urine flow rates (UF) between the groups during any phase, though UF decreased in Group I from the prehypotensive value 0.58 +/- 0.12 ml.min-1 to 0.07 +/- 0.02 ml.min-1 during hypotension (P less than 0.01) and increased to 1.28 +/- 0.17 ml.min-1 after anaesthesia (P less than 0.05). UF in Group II were 0.56 +/- 0.17, 0.25 +/- 0.10 and 0.56 +/- 0.06 ml.min-1, respectively. Creatinine clearances per 1.73 m2 body surface area (CCreat) in Group I were 78 +/- 14 ml.min-1, and in Group II 78 +/- 11 ml.min-1 before hypotension. During hypotension, CCreat were lower in Group I (8 +/- 1 ml.min-1) than in Group II (33 +/- 8 ml.min-1) (P less than 0.01). After anaesthesia, there was no difference in CCreat between the groups (Group I: 110 +/- 17 ml.min-1 and Group II: 120 +/- 17 ml.min-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Protective effect of intrauterine release of levonorgestrel on pelvic infection: three years' comparative experience of levonorgestrel- and copper-releasing intrauterine devices.

A randomized, multicenter comparison of two intrauterine contraceptive devices (IUDs) was carried out. Nine hundred thirty-seven women were fitted with a copper-releasing IUD, the Nova-T, and 1821 women with an IUD that releases 20 micrograms of levonorgestrel daily. After 36 months, the cumulative gross rates of amenorrhea and hormonal side effects were significantly higher in the levonorgestrel-IUD users. The cumulative 36-month gross pregnancy rate was 3.7 for the Nova-T and 0.3 for the levonorgestrel IUD (P less than .001), demonstrating the levonorgestrel IUD's high contraceptive efficacy. For the first time, a protective effect of the levonorgestrel IUD against pelvic inflammatory disease as compared with the Nova-T was seen statistically. The cumulative 36-month gross rate of pelvic inflammatory disease was 2.0 in Nova-T- and 0.5 in levonorgestrel-IUD users (P less than .013). This significantly lowered incidence of pelvic inflammatory disease may help to solve one of the major concerns associated with intrauterine contraception.

Adult↗
PubMed1991

Plasma renin, catecholamines, vasopressin and aldosterone during hypotension induced by labetalol with isoflurane.

Deliberate hypotension may induce secretion of stress hormones. In the present study, the effects of hypotension induced by labetalol with isoflurane or plasma renin activity, plasma concentrations of adrenaline, noradrenaline, vasopressin, and aldosterone were investigated in eight adult patients undergoing middle-ear surgery. The mean arterial pressure was 50 mmHg (6.7 kPa) during hypotension. Plasma renin activity rose significantly during anaesthesia before hypotension, being similar during hypotension and before hypotension, and in returned postoperatively to the initial level. Plasma adrenaline fell significantly during hypotension and rose after anaesthesia to the preanaesthetic level. Plasma noradrenaline rose slightly during hypotension and after anaesthesia, but not significantly. Plasma vasopressin rose significantly after anaesthesia. Plasma aldosterone increased slightly throughout the study, but not significantly during any phase. In conclusion, labetalol with isoflurane-induced hypotension seems to attenuate the stress response in these operations. During hypotension, plasma renin activity is not an essential compensatory mechanism, which antagonises the decrease of blood pressure. Plasma vasopressin has no role in regulating blood pressure during labetalol-induced hypotension.

Adult↗
PubMed1991

[Open Doors].

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Adolescent↗
PubMed1991

Effects of deliberate hypotension induced by labetalol on renal function.

The effect of deliberate hypotension induced by labetalol on renal function, was studied in 25 patients undergoing middle-ear surgery. The patients were randomized into three groups, one enflurane (E) group and two isoflurane (I and F) groups. Group F received frusemide 0.5 mg kg-1 at the onset of hypotension. The mean arterial pressure was 50 mmHg (6.7 kPa) in Groups E and I, and 49 mmHg (6.5 kPa) in Group F during hypotension. During hypotension, urine flow rate, effective renal blood flow, endogenous creatinine clearance, and osmolar clearance decreased. Free-water clearance and fractional electrolyte excretions also indicated deterioration of renal function during hypotension, but it returned to normal after anaesthesia. The effects of frusemide appeared mainly after anaesthesia. Frusemide reduced the amount of labetalol and isoflurane needed to maintain hypotension. Serum fluoride concentration did not increase to a potentially nephrotoxic level.

Acid-Base Equilibrium↗
PubMed1990

Clonidine premedication: a useful adjunct in producing deliberate hypotension.

The effect of clonidine on the dose requirements of labetalol and isoflurane for hypotension was studied in 20 adult patients undergoing middle-ear surgery. Group I (10 patients) received as premedication only pethidine 1 mg.kg-1 i.m., and Group II (10 patients) clonidine 4-5 micrograms.kg-1 p.o. in addition to pethidine. Fentanyl was used for analgesia and d-tubocurarine for muscle relaxation. The dose of labetalol required to induce hypotension to the mean arterial pressure (MAP) 50 mmHg (6.7 kPa) was 0.85 +/- 0.08 mg.kg-1 in Group I, and 0.56 +/- 0.08 mg.kg-1 in Group II (P less than 0.05). The mean isoflurane concentration in inspiratory gas for the maintenance of hypotension was 0.8 +/- 0.1 vol% in Group I, and 0.6 +/- 0.1 vol% in Group II (P less than 0.05). Before hypotension, MAP decreased significantly in Group II, and the heart rate (HR) decreased in both groups. There were no significant differences in MAP and HR between the groups during any phase. Urine flow rates (UF) were lower in Group II (0.23 +/- 0.04 ml.min-1) than in Group I (0.68 +/- 0.16 ml.min-1) before hypotension (P less than 0.05) and during hypotension (0.08 +/- 0.02 ml.min-1 vs. 0.68 +/- 0.32 ml.min-1, P less than 0.05). After anaesthesia, there was no difference in UF between the groups. The results indicate that clonidine can be used for deliberate hypotension to decrease the dose requirements of labetalol and isoflurane.

Adult↗
PubMed1990

Levonorgestrel-releasing intrauterine device.

An intrauterine contraceptive device releasing 20 micrograms levonorgestrel daily has been studied for 15 years. The international clinical experience covers over 8000 woman years. Main characteristics of the levonorgestrel-releasing intrauterine device are its great effectiveness in preventing unplanned pregnancies and a reduction in menstrual bleeding and pain as well as a low infection rate.

Contraceptive Agents, Female↗
PubMed1989

Acceptability of an experimental intracervical device: results of a study controlling for selection bias.

We analyzed baseline and 12-month follow-up interview data from 98 women who had volunteered to use an experimental intracervical device (ICD) and from 155 women who had been randomly assigned to two control groups, the levonorgestrel-releasing intrauterine device (LNG-IUD; N = 86) and the copper Nova-T IUD (N = 69). All participants were clinic patients in Helsinki, Finland. Initial analysis of 12-month discontinuation data indicated that a significantly higher percent of ICD users (22.4) discontinued their device than did either LNG-IUD (7.0) or Nova-T (8.7) users. However, we were no longer able to detect significant differences in discontinuation after controlling for baseline variables that assessed predisposition to be dissatisfied with contraception in general. Adjusted probabilities of discontinuing the ICD, LNG-IUD, and Nova-T were 11.8%, 6.2% and 7.9%, respectively. These data indicate that the ICD is likely to be acceptable to Helsinki clinic patients; moreover, they suggest a definite place for hormonal intrauterine devices in the contraceptive armamentarium. Most importantly, the methodology used here can be generalized to acceptability studies of other contraceptive devices and drugs undergoing Phase I and early Phase II clinical trials (in situations where randomization may not be feasible) in order to identify and control for the bias introduced by nonrandom assignment procedures.

Adolescent↗
PubMed1989

Plasma levonorgestrel levels and ovarian function during the use of a levonorgestrel-releasing intracervical contraceptive device.

Levonorgestrel, estradiol and progesterone plasma concentrations were measured over four years of use of a 20 micrograms/day levonorgestrel-releasing intracervical device (LNG-ICD). The mean levonorgestrel concentration showed a slight decline, being 142 + 46 (SD) pg/ml in the third month and 81 +/- 22 pg/ml in the 48th month of LNG-ICD use. However, considerable interindividual variation in levonorgestrel plasma levels between study subjects was observed. In 77% of the monitored cycles, ovulation or a luteinized follicle was observed when judged by a plasma progesterone elevation of over 5 ng/ml. Some follicular function was also noted in anovulatory cycles. Inhibition of ovulatory ovarian function is not the mode of contraceptive action of the LNG-ICD.

Adult↗
PubMed1989

Deliberate hypotension induced by labetalol with halothane, enflurane or isoflurane for middle-ear surgery.

The feasibility of using labetalol, an alpha- and beta-adrenergic blocking agent, as a hypotensive agent in combination with inhalation anaesthetics (halothane, enflurane or isoflurane) was studied in 23 adult patients undergoing middle-ear surgery. The mean arterial pressure was decreased from 86 +/- 5 (s.e. mean) mmHg to 52 +/- 1 mmHg (11.5 +/- 0.7 to 6.9 +/- 0.1 kPa) for 98 +/- 10 min in the halothane (H) group, from 79 +/- 5 to 53 +/- 1 mmHg (10.5 +/- 0.7 to 7.1 +/- 0.1 kPa) for 129 +/- 11 min in the enflurane (E) group, and from 80 +/- 4 to 49 +/- 1 mmHg (10.7 +/- 0.5 to 6.5 +/- 0.1 kPa) for 135 +/- 15 min in the isoflurane (I) group. The mean H concentration during hypotension in the inspiratory gas was 0.7 +/- 0.1 vol%, the mean E concentration 1.6 +/- 0.2 vol%, and the mean I concentration 1.0 +/- 0.1 vol%. In addition, the patients received fentanyl and d-tubocurarine. The initial dose of labetalol for lowering blood pressure was similar, 0.52-0.59 mg/kg, in all the groups. During hypotension, the heart rate was stable without tachy- or bradycardia. The operating conditions regarding bleeding were estimated in a double-blind manner, and did not differ significantly between the groups. During hypotension, the serum creatinine concentration rose significantly in all groups from the values before hypotension and returned postoperatively to the initial level in the other groups, except the isoflurane group. After hypotension there was no rebound phenomenon in either blood pressure or heart rate. These results indicate that labetalol induces easily adjustable hypotension without compensatory tachycardia and rebound hypertension.

Adult↗
PubMed1988

Patterns of bleeding and body iron stores during the use of a levonorgestrel-releasing intracervical device.

A levonorgestrel-releasing intracervical device (LNG-ICD) was inserted in 198 women. The subjects registered bleeding and spotting days on special cards, which were analyzed after one year of treatment. Bleeding and spotting days gradually declined from sixteen during the first month to seven during the seventh month, and they remained under that level until the end of the first year. There were more days of spotting than bleeding. Eleven per cent of the subjects experienced at least 90 days non-bleeding interval during the first year of LNG-ICD use. There were no significant changes in blood hemoglobin concentrations during the first four years of LNG-ICD use. The mean serum ferritin concentration increased from 38 micrograms/l at the beginning to 97 micrograms/l at the end of the fourth year.

Adolescent↗
PubMed1987

Effective contraception with the levonorgestrel-releasing intrauterine device: 12-month report of a European multicenter study.

The use-effectiveness of an intrauterine contraceptive device releasing 20 mcg of levonorgestrel daily (Lng-IUD), and of a Nova T copper-releasing IUD, were studied in a randomized, comparative multicenter trial. The Lng-IUD was inserted in 1821, and the Nova T in 937 women. The 12-month net pregnancy rate with the Lng-IUD (0.1 per hundred women) was significantly lower than that with the Nova T (0.9 per hundred). Removal rates for menstrual problems and/or pain were similar for the two methods (net rates 7.5 and 8.7, respectively). The 12-month continuation rates were 82.2 for the Nova T and 79.7 for the Lng-IUD. The reduction of the bleeding led to oligomenorrhea and amenorrhea in users of the Lng-IUD; the removal rate for these reasons was 1.4. The removal rate for hormonal side effects with the Lng-IUD was 2.4. Blood hemoglobin concentrations increased among users of the Lng-IUD and decreased among users of the Nova T. The results show that the Lng-IUD was a highly effective contraceptive method which reduced menstrual bleeding. It is a promising alternative for women desiring a highly effective method for long-term use.

Adult↗