Biomedical subjects

H G Lovell

Publications and source records attributed to H G Lovell.

At least 19 recordsLinked to original sources

PubMed1991

Caffeine restriction: effect on mild hypertension.

OBJECTIVE: To determine the effects on blood pressure of modifying dietary caffeine intake in patients with mild and borderline hypertension by monitoring ambulatory and clinic blood pressure. DESIGN: Four way, randomised, crossover trial of four consecutive two week dietary regimens: normal diet, caffeine free diet alone, caffeine free diet with decaffeinated instant coffee, caffeine free diet with caffeinated instant coffee (instant coffee phases conducted double blind). SETTING: Hospital hypertension clinic, Scotland. PATIENTS: 52 patients (23 men; aged 26-67 years) with untreated borderline or mild hypertension (diastolic blood pressure 90-105 mm Hg) who normally drank a minimum of three cups of coffee daily. MAIN OUTCOME MEASURES: Mean ambulatory blood pressure over 24 hours; mean morning, daytime, and night time ambulatory blood pressure; sitting clinic blood pressure at 1700; plasma caffeine concentration at 1700 on the last day of each regimen. RESULTS: Mean 24 hour ambulatory blood pressure was not different between regimens. There was no difference in blood pressure variability between regimens. During the caffeine free diet alone morning ambulatory diastolic blood pressure was higher (2.8 mm Hg) than during the caffeine free diet with caffeinated coffee. Mean sitting clinic systolic blood pressure was higher at 1700 (4.7 mm Hg) with a caffeine free diet than with the caffeine free diet with caffeinated coffee (p less than 0.05). Dietary compliance as assessed by plasma caffeine concentration was excellent. There was no significant correlation between plasma caffeine concentration and blood pressure. CONCLUSIONS: Drinking caffeinated instant coffee over a two week period does not adversely influence blood pressure in patients with borderline or mild hypertension; abstinence is of no benefit.

Adult↗

PubMed1990

The measurement of blood pressure: sitting or supine, once or twice?

In 166 patients attending a hypertension review clinic, we compared supine and sitting blood pressure measurements and first and second measurements (1 min apart) in each position to determine whether any differences seen might have implications for the routine measurement of blood pressure in these patients, as a group or as individuals. Measurements were made with the Copal UA-251 semi-automated sphygmomanometer. In the group there was no significant difference between the first and the second diastolic measurements. The first systolic measurement was on average 3-4 mmHg higher than the second in both positions. Mean supine systolic pressures were 2-3 mmHg higher and diastolic pressures 2-3 mmHg lower than the corresponding sitting pressures. In individual subjects there were substantial disagreements between successive measurements in both positions and between positions. However, these differences would not have influenced blood pressure management in more than a few instances. We suggest that two measurements should routinely be taken, and the average recorded, particularly when the average exceeds 155/90 mmHg.

Blood Pressure Determination↗

PubMed1987

Atenolol or propranolol in hypertensive patients poorly controlled on captopril and frusemide.

Eighteen patients whose clinic blood pressure (BP) remained over 95 mmHg despite treatment with captopril 50 mg twice daily plus frusemide 40 mg twice daily were randomised in a crossover study to four weeks' treatment with once daily atenolol 100 mg, slow release propranolol 160 mg or placebo. The reduction in BP on atenolol was superior to that on both propranolol and placebo. The mean supine BP 24 hours post dosing were 177/110 mmHg (placebo), 173/109 mmHg (propranolol) and 164/100 mmHg (atenolol). The corresponding mean heart rates were 77 bpm (placebo), 63 bpm (propranolol) and 62 bpm (propranolol) and 62 bpm (atenolol). The difference in hypotensive efficacy between atenolol and propranolol is not readily explained but our study shows that atenolol has a clinically useful supplementary effect on BP. Refractory hypertension remains an important clinical problem and further studies are required to establish the optimum combination of drugs that should be used with captopril in order to achieve 'target' BP in patients with moderate to severe hypertension.

Aged↗

PubMed1984

Influence of arm position on measurement of blood pressure.

A series of measurements of blood pressure in normotensive and hypertensive subjects showed that measurements made with a sphygmomanometer with the arm dependent by the side were consistently higher than those made with the arm horizontal at heart level. The mean difference in a group of 90 hypertensive outpatients was 11/12 mm Hg. Failure to appreciate the importance of arm position may lead to erroneous measurements of blood pressure. This has important implications for clinical practice and research.

Arm↗

PubMed1982

Atenolol and metoprolol once daily in hypertension.

The effect of once-daily dosage of the two most widely prescribed cardioselective beta-adrenoceptor antagonists used to treat hypertension--namely, atenolol and metoprolol--was studied in nine carefully selected hypertensive outpatients. Each patient received atenolol 50 mg/day, atenolol 100 mg/day, metoprolol 100 mg/day, and metoprolol 200 mg/day in a sustained-release formulation (as Lopresor SR) according to a randomised sequence. After three weeks' treatment with each drug given once daily comparisons of the treatments 24 hours after dosing showed no important differences between 50 and 100 mg atenolol/day. Metoprolol, as both the standard and the slow-release formulations, had some limitations in controlling systolic blood pressure and heart rate. These results suggest that the recommendations for the treatment of hypertension with these cardioselective beta-adrenoceptor antagonists should be reconsidered since doses smaller than those recommended are almost as effective and much cheaper.

Adult↗

PubMed1972

Interaction of prostaglandin E 1 and calcium in the guinea-pig myometrium.

1. Prostaglandin E(1) (PGE(1)) increased the responses of guinea-pig myometrium in a low calcium medium to added Ca(2+), acetylcholine, vasopressin, Ba(2+) and Sr(2+). The concentration of PGE(1) used (50 pg/ml) was clearly below the threshold for direct spasmogenesis. In the presence of PGE(1) the doses necessary for half-maximal contractions were decreased by factors of 2.6 for Ca(2+), 2.4 for acetylcholine, and 3.7 for vasopressin. The responses to Ba(2+) or Sr(2+), though studied less extensively, were found to be affected in much the same manner.2. The K(+) depolarized myometrium in a low Ca(2+) medium contracts in response to added Ca(2+). These responses also were increased by low concentrations of PGE(1), but the effective concentration of PGE(1) was indistinguishable from that for direct spasmogenesis.3. Possible mechanisms for the interaction of PGE(1) and Ca(2+) in the myometrium are discussed. It is tentatively suggested that these findings may be relevant to the physiological control of human myometrium.

Acetylcholine↗

PubMed1969