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Biomedical subjects

B J Materson

Publications and source records attributed to B J Materson.

At least 73 records · Page 4Linked to original sources
PubMed1989

The effects of administration of lithium salts and magnesium sulfate on the serum anion gap.

Whether or not an increased serum level of an unmeasured cation will reduce the anion gap (AG) depends on concomitant changes (or lack thereof) in serum unmeasured anions. In the present retrospective study, we sought to determine the effect of lithium carbonate or citrate and magnesium sulfate on the AG. Two groups of psychiatric patients whose average serum lithium levels were 0.6 and 1.0 mEq/L were studied. The AG in each group (10.2 +/- 0.3 [SE] and 9.0 +/- 0.4 mEq/L, respectively) was significantly (P less than 0.05) lower than that of a control group (11.1 +/- 0.3 mEq/L). Separately, we collected 87 pairs of AG and serum magnesium data of patients with toxemia of pregnancy. These included those of 15 patients evaluated both before and during magnesium sulfate infusion. Despite an average serum magnesium level of 4.1 +/- 0.2 mEq/L, the AG of the latter subjects tended to increase slightly from 10.8 +/- 0.5 to 11.7 +/- 0.7 mEq/L during magnesium infusion, instead of decreasing. The other data (72 determinations in the 55 patients without preinfusion values) revealed a mean AG of 11.0 +/- 0.3 mEq/L, coexisting with an elevated serum magnesium of 4.1 +/- 0.1 mEq/L. None of the above-mentioned three mean AG values differed significantly from that of the control group. We conclude that hypermagnesemia resulting from the administration of magnesium sulfate does not reduce the AG, probably because of a concomitant and proportional increase in serum sulfate. The present data reemphasize the need to assess the anion gap as the result of concomitant changes in both unmeasured anions and cations.

Acid-Base Equilibrium↗
PubMed1989

Newer principles of patient profiling for antihypertensive therapy.

The mosaic of essential hypertension seems to be gaining new tiles at an accelerating rate. Of the many pathophysiological factors and markers for the factors that can be considered as possible elements of a profiling algorithm, there are relatively few with solid data to support their use. Use of plasma renin activity for prospective profiling does not appear to be valid for individual patients. It remains useful for diagnosis of renal artery stenosis and primary aldosteronism. The black race does have some well-documented pathophysiological differences from the white race regarding hypertension, and there are some useful data bits for selecting specific therapy. The elderly, obese patients, and young patients with hyperdynamic circulation appear to have enough group characteristics to enable selection of drugs more targeted to their needs. Anxious patients who often display symptoms that mimic pheochromocytoma symptoms comprise a unique group. One of the largest groups is patients with hypertension plus one or more concomitant diseases. Finally, drug selection decisions must also consider the effect of drugs on serum lipoproteins, left ventricular hypertrophy and vascular compliance, sexual function and other quality of life issues, and cost.

Age Factors↗
PubMed1988

Use of the anion gap in clinical medicine.

The anion gap (AG) in the serum equals the concentrations of Na-(Cl + HCO3). It is becoming increasingly useful in the interpretation of acid-base disorders and in the diagnosis of other conditions. In an acidemic patient, an elevated AG usually indicates the presence of an organic acidosis, rhabdomyolysis, nonketotic hyperglycemic coma, uremia, or certain intoxications. An increased AG with alkalemia suggests severe alkalosis with hemoconcentration or use of anionic antibiotics (eg, carbenicillin) or salts of organic acids (eg, citrate). An elevated AG with a normal serum pH could be an artifact caused by prolonged exposure of the serum sample to air before processing. A decreased AG with a normal serum pH may indicate hypoalbuminemia, cationic paraproteinemia, halide poisoning, or lithium intoxication. The delta AG/delta HCO3 ratio and the urinary AG may also be quite useful in analyzing complex acid-base disorders.

Acid-Base Equilibrium↗
PubMed1988

Volume (weight) loss and blood pressure response following thiazide diuretics.

Correlations were made between weight change (as an index of volume loss) and blood pressure (BP) reduction before and after hydrochlorothiazide treatment. A total of 343 patients with mild to moderate hypertension (95-114 mm Hg) received hydrochlorothiazide alone. The diuretic was titrated from 50 to 100 to 200 mg daily as needed until the diastolic BP fell below 90 mm Hg (goal BP) or side effects supervened. Of the 305 patients who completed the 10-week titration period, 65% attained goal BP. The effective dose of hydrochlorothiazide in 52% of these responders was 50 mg/day, and this was associated with weight loss averaging 1.58 kg. An additional 29% achieved goal BP with a similar degree of weight loss, but they required double the dose, or 100 mg/day. The remaining 19% of responders required significantly greater weight reductions averaging 3.14 kg to achieve goal BP, which necessitated hydrochlorothiazide, 200 mg/day. More blacks than whites attained goal BP despite similar degrees of weight loss in the two races. Plasma renin activity was initially higher in whites than in blacks and rose significantly more in blacks and whites requiring the greatest volume losses and the highest dose of hydrochlorothiazide to attain goal BP. Nonresponders had less weight loss than responders. Thus, diuretic dose requirements vary in different patients and are related either to different volume losses in response to a given dose or to different degrees of BP reduction in response to the same volume loss.

Black People↗
PubMed1988

Cigarette smoking interferes with treatment of hypertension.

We retrospectively analyzed two studies to determine whether smoking affected the treatment of hypertension. In a study of the effects of propranolol hydrochloride (a hepatically metabolized beta-blocker) vs hydrochlorothiazide, 108 smokers and 232 nonsmokers were randomized to the propranolol treatment group. The propranolol-treated smokers tended to be younger, taller, thinner, and wre more likely to be black. This group also had an initial blood pressure reduction (+/- SD) of -7.9 +/- 12.9/-8.7 +/- 8.4 mm Hg compared with -10.7 +/- 13.0/-10.9 +/- 7.1 mm Hg for the nonsmokers. Blood pressure increased less during the one-year maintenance period for the nonsmokers. However, when analyzed by race, this effect was seen in blacks, but not in whites. Diastolic blood pressure tended to be reduced more in nonsmokers (vs smokers) receiving hydrochlorothiazide (-12.1 +/- 6.7 vs -10.7 +/- 6.7 mm Hg, respectively). The second study compared the effects of nadolol (a renally excreted beta-blocker) with bendroflumethiazide. There were no significant effects on blood pressure for either of these drugs. In both studies, there was a greater tendency for smokers to be terminated from the study irrespective of drug group. We conclude that cigarette smoking does interfere with the treatment of hypertension in general, and especially with reduction of blood pressure by propranolol in black patients.

Adult↗
PubMed1988

Geriatric hypertension: the growing use of calcium-channel blockers.

The recognition of essential hypertension as a heterogeneous entity mandates that therapy be individualized according to the subset of hypertension that characterizes each patient. Choosing the most appropriate therapeutic regimen in elderly hypertensives is complicated by a greater susceptibility to side effects from medications, and by concomitant diseases. Calcium-channel blockers address the pathophysiologic mechanisms of generic hypertension, thus providing clinicians with more specific pharmacologic tools for treating elderly hypertensives. In addition, these agents will avoid many of the side effects of other antihypertensive agents and can ameliorate certain concomitant diseases.

Aged↗
PubMed1987

Evaluation of antihypertensive efficacy of lisinopril compared to metoprolol in moderate to severe hypertension.

A double-blind controlled, randomized, parallel, multicenter 12-week study was conducted to compare the antihypertensive efficacy of lisinopril with that of metoprolol in treatment of moderate to severe hypertension. Initially, 118 patients were recruited on lisinopril and 61 on metoprolol; and for the purpose of efficacy analysis at week 8, 115 patients on lisinopril and 60 on metoprolol were included. The doses of lisinopril or metoprolol were 40-80 mg/day and 100-200 mg/day, respectively. At week 4, the pretreatment diastolic blood pressure of 111 mm Hg was decreased to 97 mm Hg (p less than 0.01) with lisinopril: metoprolol decreased the diastolic blood pressure from 110 to 99 mm Hg (p less than 0.01). Similar decreases were noted at week 8; however, the drop in blood pressure with lisinopril was not significantly different from that with metoprolol. Systolic blood pressure also demonstrated a decrease of about 18 mm Hg with lisinopril and 12 mm Hg with metoprolol (p less than 0.01). This larger decrease in systolic blood pressure with lisinopril was statistically significant at week 4 (p less than 0.05). These decreases in systolic blood pressures were maintained at week 8, again with statistical significance (p less than 0.01). Of the 118 lisinopril-treated patients, four were discontinued from lisinopril therapy because of headache, dizziness, rash, flushing, or lymphadenopathy. Four patients out of 61 (9.8%) were discontinued from metoprolol therapy because of fatigue, somnolence, asthenia, weight gain, flatulence, tremor, or bronchospasm. In conclusion, lisinopril 40-80 mg once daily is as effective as metoprolol 100-200 mg once daily in reducing diastolic blood pressure in patients with moderate to severe hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1987

Special uses for captopril.

Plasma renin activity (PRA) is markedly increased by captopril. There is not enough separation between the changes in PRA of patients with renal artery stenosis (RAS) to separate them reliably from those with essential hypertension. A minimal response may suggest primary aldosteronism. Captopril does increase the ratio of PRA in the venous blood from a kidney with RAS to that of the contralateral kidney. Captopril, 25 to 50 mg orally, given before renal vein PRA sampling will increase the sensitivity and specificity of the test. Treatment with current antihypertensive drugs need not be discontinued. Scleroderma renal crisis (SRC) used to be uniformly lethal within a few months. Modern, aggressive antihypertensive therapy has made survival of 2 or more years common. Not all patients respond, and some progress to renal failure despite good BP control. Captopril has been used with success in some patients with idiopathic edema. In conclusion, captopril markedly enhances the accuracy of renal vein renin assay for the diagnosis of RAS and is of major value in the treatment of SRC.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1986

A multicenter, randomized, double-blind dose-response evaluation of step-2 guanfacine versus placebo in mild to moderate hypertension.

Guanfacine, an alpha-adrenoceptor agonist, may exhibit distinct dose-related curves for efficacy and adverse effects in the step-2 therapy of essential hypertension. To determine the lowest clinically effective safe dose, 462 newly or previously diagnosed subjects were admitted to a 5-week prerandomization phase at 8 centers. Patients were weaned from any current antihypertensive drugs and placed on 25-mg chlorthalidone, daily, in the morning. At the end of the 5-week weaning period, 362 patients with seated diastolic blood pressures (BPs) between 95 and 114 mm Hg qualified for the 12-week postrandomization phase. Subjects were randomized to receive either an indistinguishable placebo or 0.5, 1, 2 or 3 mg of guanfacine. Chlorthalidone was changed to bedtime administration and taken with the study medications. Guanfacine was started at the lowest dose in all subjects and increased (if scheduled, according to the randomization code) to the next higher dose at biweekly intervals. Of the 362 randomized patients, 278 completed the study. The 1-mg guanfacine dosage produced a 14/13 mm Hg decrease in BP (p less than 0.0125 compared with placebo). Doses of guanfacine at 2 and 3 mg/day were not more effective than the 1 mg/day dose; 0.5 mg/day was not better than placebo. There was an increase in the frequency of side effects possibly or probably associated with 2 and 3 mg/day guanfacine. Only 3.2% of the patients in the 1 mg/day group dropped out of the study because of side effects. We conclude that when added to a diuretic, 1 mg/day guanfacine at bedtime is the lowest safe and therapeutically effective dose.

Administration, Oral↗
PubMed1986

Adverse effects of antihypertensive treatment.

Elevated blood pressure can be lowered safely in the vast majority of patients by selecting the single drug most likely to be efficacious in that patient. Skillful management with full knowledge of drug pharmacology should provide the patient with the maximum opportunity to benefit from normalization of blood pressure while at the same time having little or no impact on quality of life.

Adrenergic beta-Antagonists↗
PubMed1986

Pseudohypertension: a diagnostic dilemma.

Pseudohypertension is a condition in which the indirect measurement of intra-arterial pressure using a sphygmomanometer (cuff pressure) is artifactually high in comparison with directly measured intra-arterial pressure. If unrecognized, pseudohypertension may result in unwarranted and sometimes dangerous treatment. Pseudohypertension results from medial sclerosis and/or calcification of arteries, which markedly decrease their collapsibility. Both the systolic and diastolic pressures are affected. The literature concerning pseudohypertension is quite limited; indeed, the very frequency of the condition is unknown. Very high blood pressure in the absence of significant target organ impairment is an important clue to this subtype of hypertension and should lead to simple diagnostic techniques, such as Osler's maneuver (an attempt to palpate a pulseless radial artery) and radiographs of the soft tissues of the arms. The definitive diagnosis is made by comparing the intra-arterial pressure with the indirectly determined blood pressure.

Aged↗
PubMed1985

Comparative effects of diltiazem and hydrochlorothiazide in blacks with systemic hypertension.

The blood pressure-lowering effects of a calcium-entry blocker, diltiazem (240 or 360 mg/day), and a thiazide diuretic, hydrochlorothiazide (50 or 100 mg/day), were studied in 20 black hypertensive patients. Supine blood pressure decreases of -34/-18 mm Hg for diltiazem and -29/-21 mm Hg for hydrochlorothiazide were noted after 14 weeks of therapy. Differences between drugs were not significant. Blood pressures were normalized in all 4 of the monotherapy nonresponders when the 2 drugs were combined. Significant adverse effects were not noted. These data suggest that diltiazem is an effective antihypertensive agent in black patients. As monotherapy, its blood pressure-lowering effect is equivalent to hydrochlorothiazide.

Adult↗
PubMed1985

Monotherapy with labetalol compared with propranolol. Differential effects by race.

The antihypertensive effect of oral labetalol and propranolol were evaluated in 65 black and 75 white patients with mild to moderate hypertension (standing diastolic blood pressure (StDBP) of 90-115 mmHg) in a double-blind multicenter clinical trial. Following a 4-week placebo phase, labetalol (n = 70) or propranolol (n = 70) was randomly assigned. During a 5-week titration phase, labetalol could be increased from 100 mg BID to 600 mg BID to achieve a StDBP of less than 90 mmHg and a decrement of greater than or equal to 10 mmHg. Propranolol could be titrated from 40 to 240 mg BID. A 3-month maintenance phase was followed by an optional 8-month maintenance phase. Hydrochlorothiazide (HCTZ) could be added at any time during the maintenance phase. Supine and standing blood pressures were measured at each visit. Statistical analysis revealed significant (ANOVA, p less than 0.05) treatment by race effects. Therefore, the treatment groups were stratified retrospectively by race. This study demonstrated that labetalol is equally effective in white and black patients, whereas, propranolol is significantly (p less than 0.05) more effective in white than in black patients. Moreover, labetalol is significantly more effective than propranolol in lowering the standing systolic/diastolic blood pressure of black patients (p less than 0.02/p less than 0.001). These blood-pressure effects were accompanied by a significantly greater (p less than 0.04) reduction in heart rate with propranolol. Furthermore, significantly more (p less than 0.05) black patients treated with propranolol compared to those treated with labetalol required the addition of a diuretic for control of their blood pressure.

Adult↗
PubMed1984

Monotherapy of hypertension with angiotensin-converting enzyme inhibitors.

Angiotensin-converting enzyme (ACE) inhibitors are clearly effective treatment for all stages of hypertension. Since the introduction of captopril in 1981, numerous ACE inhibitors have been synthesized and are under investigation. Their exact antihypertensive mechanism of action remains unclear. Part of their effect may be mediated by vasodilator prostaglandins. Early studies with as much as 1,000 mg a day captopril demonstrated the agent's ability to reduce blood pressure, but only 10 percent of the severely hypertensive patients were controlled with monotherapy. Subsequent studies have demonstrated that patients with mild to moderate hypertension can be controlled with ACE inhibitor alone, although there is a tendency for the very low doses to lose their effect with time. Black patients are less readily controlled with monotherapy. Captopril has now been demonstrated to be effective in the hypertension of scleroderma and has reversed scleroderma renal crisis. ACE inhibitors are also effective for the treatment of severe congestive heart failure.

Acute Kidney Injury↗