Paul L Padfield

Use and interpretation of ambulatory blood pressure monitoring: recommendations of the British Hypertension Society

Over the past 20 years or so, the accuracy of using the conventional Riva-Rocci sphygmomanometer and Korotkoffs sounds to measure blood pressure has been questioned, and efforts have been made to improve measurements with automated devices.1 2 In the same period, the phenomenon of white coat hypertension has been recognised—whereby some patients who apparently have raised blood pressure actually have normal blood pressure when the measurement is repeated away from the medical environment; this has focused attention on methods of measurement that provide profiles of blood pressure rather than rely on isolated measurements made under circumstances that may influence blood pressure.3 These methods have included repeated measurements of blood pressure using the traditional technique, self measurement of blood pressure in the home or workplace, and ambulatory blood pressure measurement using automated devices.2 Ambulatory monitoring is advantageous because it gives multiple measurements throughout the day and nightnnThis paper considers only the ambulatory measurement of blood pressure in adults. Its purpose is not to make a case for or against ambulatory measurement; others have already done so.4 5 Although the results of a number of ongoing, longitudinal studies are forthcoming, there is now firm evidence that ambulatory blood pressure measurement is a more sensitive predictor of cardiovascular outcome than conventional measurement.6 We have not considered the complex issues of health economics that the increasing use of ambulatory measurement raises.7 We realise that this technique is being used more often and that doctors who find ambulatory measurement useful in the day to day management of patients with high blood pressure need recommendations from those who have experience. However, regardless of the technique used to diagnose hypertension it is only one factor in determining a patients risk profile and must be assessed in relation to concomitant disease, …

Disorders of sodium balance.

Disorders of plasma sodium are the most common electrolyte disturbances in clinical medicine, yet they remain poorly understood. Severe hyponatraemia and hypernatraemia are associated with considerable morbidity and mortality,1–3 however, and even mild hyponatraemia is associated with worse outcomes when it complicates conditions such as heart failure,4 although which is cause and which effect is often uncertain. Distinguishing the cause(s) of hyponatraemia may be challenging in clinical practice, and controversies surrounding its management remain. Here, we describe the common causes of disorders of plasma sodium, offer guides to their investigation and management, and highlight areas of recent advance and of uncertainty.nnWe incorporated the latest consensus from systematic reviews and publications identified by a literature search through Medline and Web of Science with the search strategy terms “hyponatraemia,” “hypernatraemia,” and “sodium.” We found fewer than a dozen randomised controlled trials of treatment of any description. Despite their frequency, plasma sodium disorders have not been reviewed by the Cochrane Library, Clinical Evidence, or Best Evidence.nnUnder normal conditions, plasma sodium concentrations are finely maintained within the narrow range of 135-145 mmol/l despite great variations in water and salt intake. Sodium and its accompanying anions, principally chloride and bicarbonate, account for 86% of the extracellular fluid osmolality, which is normally 285-295 mosm/kg and calculated as (2× [Na]mmol/l + [urea]mmol.l + [glucose]mmol/l. The main determinant of the plasma sodium concentration is the plasma water content, itself determined by water intake (thirst or habit), “insensible” losses (such as metabolic water, sweat), and urinary dilution. The last of these is under most circumstances the most important and is predominantly determined by arginine vasopressin, which is synthesised in the hypothalamus and then stored in and released from the posterior pituitary. In response to arginine vasopressin, concentrated urine is produced by water reabsorption …

Skin Reactions to Beta-blockers

patients in suoh evaluations were overlooked. Evaluation should not be considered as anything but constructive for those evaluated. It should provide feedbaok to improve patient care. Those involved in an evaluation with simulated patients should agree to the valuation. In addition, they must be instrumental in the design of the evaluation, especially the observations to be made by the simulator. Of course, the simulated patient does not have to be personally involved in the evaluation. Since the simulated patient offers a standardized, unvarying medical problem, subsequent analysis of health needs produced by those who cared for the simulated patient can be carried out. However, if the simulated pa,tient is to be involved in observation it is imperative that he be trained for consistency and objectivity. The anonymrity of the simulation assures that no special treatment is given to this patient either consciously or unconsciously, as he is not recognized as being different from the real patients in the system. The statement that simulated patients would be a drain on health care costs seems exaggerated. The cost of the odd non-patient should be well overbalanced by the value of the exercise in improved efficiency and effectiveness in real patient care. Quality control, to be effective, has a calculated cost. Though your article mentions other methods for evaluating health care, none is as direct as measuring the effect of health care delivery on patients by putting a standardized patient into the systemn. Many factors important to patient care cannot be detected by visits or by interviews of patients who are dependent on the health care system in which they are involved. The great value of feediback provided by simulated patients to students, physicians, and nurses over the 12 years that I have utilized the technique has been amply demonstated. In addition, the persons evaluated almost almays appreciate the value of the information and insist on more evaluations of themselves by this technique. -I am, etc., H. S. BARROWS McMaster University, Hamilton, Ontario

Phosphodiesterase type 5 inhibition reverses impaired forearm exercise-induced vasodilatation in hypertensive patients.

Objective Established hypertension is characterized by increased peripheral vascular resistance and endothelial dysfunction, features that may underlie the reduced exercise-induced vasodilatation seen in hypertensive patients. Sildenafil citrate is a phosphodiesterase type 5 (PDE5) inhibitor used clinically for the treatment of male erectile dysfunction. Its vasodilating properties are due to the inhibition of cyclic guanosine monophosphate (cGMP) breakdown and prolongation of the signalling actions of the nitric oxide (NO)–cGMP pathway in vascular smooth muscle cells. Sildenafil has beneficial effects on endothelial function and exercise tolerance in congestive heart failure and pulmonary hypertension, and we hypothesized that it would improve exercise-induced vasodilatation in hypertensive patients. Methods and results Ten hypertensive patients and ten matched normotensive subjects were studied in a three-way, randomized, single-blind and placebo-controlled study. On each study day, forearm blood flow (FBF) responses to handgrip exercise were assessed before and after intra-arterial (brachial) infusion of sildenafil, verapamil (a control, cGMP-independent vasodilator), and saline (placebo). Preinfusion exercise-induced vasodilatation was significantly reduced in hypertensive patients compared to normotensive controls. Sildenafil and verapamil infusions both caused a similar increase in baseline FBF. However, while verapamil did not affect the vasodilator response to handgrip exercise in either group, sildenafil substantially enhanced this response in hypertensive patients, but not in normotensive subjects. Conclusions Our data suggest that sildenafil, through an increase in cGMP levels in the vasculature, substantially and selectively improves the vasodilator response to handgrip exercise in hypertensive patients. These findings represent an essential first step in support of further studies exploring the potentially beneficial effects of PDE5 inhibition on impaired exercise capacity in hypertension.

Computerized reporting improves the clinical use of ambulatory blood pressure measurement.

BackgroundAmbulatory blood pressure measurement (ABPM) is being used increasingly in clinical practice. One previous study has shown that there can be considerable variance between expert observers in the interpretation of ABPM data. The purpose of this study was to show whether computer-generated reports with the dabl®ABPM system would provide more consistency in the interpretation of data than reports from expert observers. MethodsTwenty-six international experts in hypertension were invited to participate and 17 agreed to do so. Twelve ABPMs generated by the Spacelabs device that were considered representative of the patterns likely to be seen in practice were sent to each participant for reporting. The corresponding dabl reports with an automatic interpretation were generated according to the European Society of Hypertension guideline for comparison with the observer reports. Each of the observer-interpreted Spacelabs reports for the 12 ABPM patterns were coded, analysed and compared with the automatically interpreted dabl®ABPM reports. Both sets of data were analysed for interobserver variability, observer v dabl®ABPM consistency and the time taken for observer reportage. The main analysis determined issues of definite disagreement, namely the presence or absence of nocturnal dipping. Further analysis determined the presence or absence of white-coat phenomena and the severity of hypertension. ResultsIncorrect diagnoses were made in 13 instances. White-coat hypertension and white-coat effect, although obvious in many instances, were not identified in five ABPMs; the severity of hypertension was not reported in four ABPMs; the severity of nocturnal hypertension was not diagnosed in one ABPM by nine experts and isolated diastolic hypertension was not identified by six experts in two ABPMs. ConclusionThis study provides evidence to show that observer variance in reporting ABPMs is common even among experts and that computer-generated interpretative reports of ABPM data improve the diagnostic decisions based on the data generated by 24-h blood pressure recording.

Measuring blood pressure: who and how?

The measurement of blood pressure (BP) is often described as the commonest procedure carried out by doctors in the care of patients. The community-based BP measurement is usually performed to diagnose or manage hypertension, a condition with at least 30% prevalence in the Western world. It would see

Aldosterone and refractory hypertension.

Purpose of reviewEvidence from clinical trials suggests that refractory hypertension is increasingly common. The underlying mechanisms are largely unknown but recent data have implicated increased aldosterone activity as an important mediator of resistance to routinely used antihypertensive agents. Recent findingsEpidemiological studies have suggested a significant rise in the prevalence of primary aldosteronism among patients with hypertension. This reflects the increasing use of an aldosterone-to-renin ratio as a screening tool. Recent reports have demonstrated that relative aldosterone excess is common in individuals with refractory hypertension, and that the use of aldosterone antagonists leads to better blood pressure control in such patients. SummaryThese data highlight the potential role of aldosterone in the pathogenesis of hypertension. The syndrome of primary aldosteronism, however, encompasses a wide spectrum of disorders that will require better definition. Similarly, although aldosterone blockade is apparently beneficial in individuals with refractory hypertension, this evidence is not currently based on robust randomized, double-blind trial.

Aldosterone and the Pathogenesis of Hypertension

Hypertension remains a major public health problem, affecting up to 20% of the adult population in Western societies. Despite progress in treatment, the rates of blood pressure control remain suboptimal. Hypertension is a heterogeneous disorder, and in the majority of cases, with so-called essential hypertension, no clear single identifiable cause is found. Syndromes of excessive mineralocorticoid production or activity are among the important causes of secondary hypertension. Aldosterone is the principal mineralocorticoid in humans, and primary aldosterone excess, when associated with an aldosterone secreting adenoma (Conns tumor), is amenable to surgical cure. Classically, patient with Conns tumor present with spontaneous hypokalemia and have a relative excess of aldosterone production with suppression of plasma levels of renin (a proxy for angiotensin II, the major trophic substance regulating aldosterone secretion). This combination of a high aldosterone and a low renin is however more commonly associated with nodular hyperplasia of the adrenal glands, a condition not improved by surgery and variably responsive to the effects of mineralocorticoid antagonists such as spironolactone. Although primary aldosteronism was previously considered to be rare, recent studies have reported prevalence rates of up to 20% among hypertensive patients. This reflects the increasing use of the plasma aldosterone concentration to renin activity ratio (ARR), rather than spontaneous hypokalemia, as a screening tool for aldosteronism. Many patients with high ARR have normokalemia and, although renin activity is low, the level of aldosterone is usually within the normal range. This group of patients may thus include those who were previously classified as having low-renin essential hypertension. Recent data suggest that disturbances in aldosterone metabolism and regulation may not be uncommon in patients with essential hypertension. Thus, relatively high serum aldosterone levels within the reference range in normotensive individuals are associated with a substantially increased risk of developing hypertension, highlighting the potential role for aldosterone in the etiology of essential hypertension. The present review addresses the physiology of aldosterone action and its role in the pathogenesis of hypertension.

Validation of blood pressure measuring devices

Validation of blood pressure measuring devices is a relatively new field of research. There are two national protocols for validating blood pressure measuring devices: the protocol of the American Association for the Advancement of Medical Instrumentation (AAMI) and the protocol of the British Hypertension Society (BHS), each of which has recently been revised. 19 blood pressure measuring devices have been validated according to one or both of these protocols. These protocols have been beneficial in drawing attention to the potential inaccuracy of blood pressure measuring systems, they permit comparison between devices and they have brought manufacturers of blood pressure measuring devices into closer contact with the profession. There are some inherent weaknesses in both protocols which include the fallibility of the gold standard, the lack of provision for validation in special circumstances and in special groups, such as the elderly and pregnant women, and failure to allow for deteriorating accuracy with higher pressure levels. The revised BHS protocol attempts to redress these deficiencies. Correspo&nce and reprint requests to: Dr. E. OBrien, Blood Pressure Unit, Beaumont Hospital, Dublin 9, Ireland, Telephone: 353-1-803865, Facsimile: 353-1803688.

Measurement of blood pressure in children: Authors' reply

population in the Paddington and North Kensington area is not registered with a general practitioner and would therefore not be included in any screening programme that is based on the family practitioner committee register. This is a cause of some concern and necessitates the implementation of alternative strategies, which bear an additional cost. We also emphasise that the problem of cervical screening is not one of simply contacting women but of achieving a response. It is worrying that our study showed that even having received an invitation letter, a significant number, particularly of older women, chose not to attend for a smear test. In our health authority valuable resources have been spent in terms of time, money, and energy in implementing a particular screening system. We remain unconvinced that it is appropriate for inner London, and we would like to see the available resources put to more effective use in an attempt to make an impact on the incidence of cervical cancer locally.