Ambulant blood pressure: reproducibility and the assessment of interventions

1. We have assessed the day-to-day reproducibility of intra-arterial blood pressure by monitoring 17 freely ambulant hypertensive patients for a period of 48 h. Eight had no change of therapeutic regimen throughout and nine took a single dose of a hypotensive agent before retiring on the second night. 2. Records were analysed to provide hourly mean values of heart rate, systolic and diastolic blood pressure. No significant differences between first and second day recordings were found except after the intervention in the second group. 3. Allowing subjects to follow their normal daily routine produces inevitable variation in their pattern of physical and other activity. However, by the use of these methods of recording and analysis, with pooled measurements from a small group of subjects, reproducibility is sufficiently good to permit the reliable assessment of therapeutic interventions.

Propranolol LA and ambulatory blood pressure

1 The technique of continuous recording of intra-arterial blood pressure in ambulant hypertensives has been used to investigate the effects of a long-acting formulation of propranolol (propranolol LA). 2 Seven subjects with untreated essential hypertension were studied before and 2 months after commencing treatment with propranolol LA once daily in the morning, results showing that smooth control of blood pressure and heart rate occurred throughout 24 h. 3 Bicycle ergometry tests performed by these subjects during both studies showed significant blood pressure reduction by propranolol LA during the mild and moderate grades of dynamic exercise. 4 In a parallel study where six treated hypertensives were monitored before and after substitution of standard propranolol by the 'LA' form, close correspondence of blood pressure throughout the 24 h occurred with each regimen.

Use of graded exercise testing in assessing the hypertensive patient

Twenty-five patients with suspected hypertension were studied using the "Oxford" continuous intra-arterial blood pressure recording technique. Each patient carried out graded exercise on a bicycle ergometer, using a standard protocol, and then underwent a fully ambulatory 24-h outpatient blood pressure recording. Using computer analysis, ambulatory blood pressure in each patient was characterised by measuring the mean daytime systolic and diastolic pressures. Exercise was found to be associated with a characteristic increase in systolic and diastolic blood pressure. Submaximal and maximal exercise blood pressures were shown to correlate strongly with ambulatory blood pressure. A much weaker correlation was found between clinic and ambulatory blood pressure. These findings suggest that the blood pressure response to exercise may be a better indicator of elevated blood pressure than a causal clinic blood pressure in individual borderline subjects.

An ambulatory trial of guanfacine

1. The effects of acute and long-term treatment with guanfacine on ambulatory BP were studied. 2. The first day of therapy with guanfacine 1 mg produced a small reduction in BP whereas chronic therapy with doses up to 6 mg given once daily produced a substantial smooth reduction throughout the whole 24 hours. 3. There were no noticeable symptoms or rebound effects on withdrawal of the drug; side-effects, were, however, prominent during therapy. 4. The drug reduced BP during dynamic exercise but did little during isometric exercise; no postural hypotension was noted during tilting.

The effects of metoprolol on ambulatory blood pressure

1. Continuous monitoring of arterial pressure was performed via an indwelling cannula over 24 h in 12 hypertensive patients before treatment and again 2-4 months after starting metoprolol (100 mg twice daily). 2. During treatment, heart rate and systolic and diastolic pressures were significantly reduced. 3. The circadian patterns of heart rate and blood pressure changes were similar before and during therapy.

Physical activity and the circadian rhythm of blood pressure

1. Ambulatory blood pressure monitoring was carried out in 10 subjects for a period of 48 h, the first or second 24 h part of which was selected randomly to be a period of complete bed rest. 2. Heart rate was significantly lower throughout the period of bed rest except for the period 04.00-08.00 hours, when there was little difference. 3. The circadian variation of blood pressure was reduced during the day of bed rest but this was mainly due to higher night-time pressures.

Effect of labetalol in hypertension during exercise and postural changes

1 Fourteen hypertensive patients were studied by intra-arterial BP monitoring to quantify the effects of standardized physiological stresses: Valsalva manoeuvre, isometric, treadmill and bicycle exercise, and 60 degree tilting before and after labetalol treatment. 2 The dose of labetalol ranged from 100--600 mg three times daily and the response was judged on outpatient clinic recordings. 3 The drug produced a sustained reduction of BP and heart rate responses during dynamic exercise and the Valsalva manoeuvre, but the degree of change from the lowered baseline were not changed by labetalol. The fall in BP on cessation of exercise was decreased rather than increased. 4 The response to controlled isometric muscle contraction was affected in a similar fashion. 5 Tilting produced a fall in BP after treatment, and this was most marked in those patients on the highest doses. However, compensatory increases in diastolic BP were observed.

Effect of labetalol on continuous ambulatory blood pressure

1 The hypotensive action of labetalol was evaluated during 24 h by continuous intra-arterial ambulatory monitoring in 14 patients. The dose used ranged from 300--1800 mg daily. 2 The drug caused a significant reduction of systolic BP in 19 and diastolic BP in 20 of the 24 h of monitoring. Heart rate was also reduced but less markedly than BP. 3 The rapid early morning increase in BP was also effectively controlled. 4 The mild pre-waking increase in BP was not significantly reduced. 5 Labetalol treatment reduced the variation in systolic BP from the lowest observed quarter-hourly mean as compared with pre-treatment values. 6 The quarter hourly mean values were consistently smooth and revealed no sudden variations which might have resulted from postural hypotension.

Blood pressure circadian rhythm in essential hypertension

1. Both systolic and diastolic blood pressure show a well defined circadian variation in ambulatory hypertensive subjects. 2. Blood pressure is highest in the mid-morning (10.00 hours) and lowest during sleep at 03.00 hours. 3. Treatment with oxprenolol (taken during the day) reduces daytime blood pressure but is less effective during the night and early morning.

Factors determining weight loss in obese patients in a metabolic ward

A metabolic unit is described in which it is possible to make controlled measurements of energy balance in patients with various types and degrees of obesity. Thirty-seven obese women were studied for three consecutive one-week periods on a diet which provided an average of 3.4MJ (800 kcal) daily, and some also undertook an exercise programme involving the expenditure of 850--1275 kJ (200--300 kcal) extra per day. The distribution of energy intake was varied from week to week, and within the day (nibbling and gorging), but neither these variations in dietary pattern nor the exercise programme significantly affected the total weight loss over the three-week study period. Very large variations were observed between individuals. Total weight loss over the three-week study period ranged from 1.6 to 9.8 kg. The best predictor of weight loss in a patient on a strictly controlled diet is the resting metabolic rate. The previous diet also affects weight loss: patients who had been keeping to a reducing diet before admission lost less weight, especially in the first week, than those who had not been dieting immediately before admission to hospital.

Prehospital cardiac arrest after arrival of the Paramedic Unit

Rapid response time by paramedic units made it possible to study 26 cases of "primary" cardiac arrests occurring after arrival of the unit. Ventricular fibrillation developed in 14 cases with prodromal ectopy in only two (14%) and rapidly increasing tachycardia in seven (50%). Countershock was successful in 12 (86%) and six (43%) survived. Bradycardia and asystole following countershock forecasted a fatal outcome. Brady-asystolic arrests (BAA) developed rapidly without much warning in 12 cases and were due to sinus arrest or severe sinus bradycardia in 92% and to atrioventricular block in 8%. BAA was 100% fatal. Coronary artery disease was diagnosed as the cause of BAA in seven (58%). All of the three cases, proven to be due to coronary artery disease at autopsy, had an occlusion of the proximal right coronary artery. In the remaining five (42%) cases, BAA was secondary to ruptured aneurysm (2), acute pancreatitis (1), chronic lung disease (1), and mitral stenosis (1). These observations emphasize a need for a more aggressive approach to prehospital management of brady-asystolic cardiac arrests.

[Changes in serum osmolarity after high contrast doses during angiography]

Analysis of changes in osmolarity of the serum after various doses of hypertonic radiographic contrast media, following a single injection, showed an initial rise of about 35 m/mosm/1, followed by a rapid fall in osmolarity with a subsequent short hypo-osmolar phase. With repeated injections, similar changes are found if the intervals between the injections are long enough. Following repeated injections over a short interval, there may be a more prolonged phase of hyperosmolarity. In this phase of delayed dehydration, there may be clinical complications. Possible forms of treatment are discussed.