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Biomedical subjects

M C Houston

Publications and source records attributed to M C Houston.

At least 37 records · Page 2Linked to original sources
PubMed1987

Pleural fluid pH: diagnostic, therapeutic, and prognostic value.

Measurement of pleural fluid pH has diagnostic, therapeutic, and prognostic implications in exudative pleural effusions (Table II). A parapneumonic effusion with a pleural fluid pH below 7.2 indicates an empyema is forming which necessitates chest tube drainage in all patients, whereas a pleural fluid pH over 7.3 does not require drainage. If the pH of a parapneumonic effusion is 7.2 to 7.3, serial pleural fluid pH measurements with clinical observation will help to determine the need for chest tube drainage. A pleural fluid glucose level of below 60 mg/dl and a lactic dehydrogenase level over 1,000 IU/dl in conjunction with a pleural fluid pH of 7.2 to 7.3 indicate an impending empyema. These findings are consistent with our clinical experience in patients with parapneumonic effusion. Tuberculous pleural effusions had a pleural fluid pH below 7.4 in all reported patients. This pH may be of value in distinguishing tuberculous pleural effusions from recent malignant effusions, which tend to have a higher pleural fluid pH, particularly if used in conjunction with other pleural fluid values, cell counts, and other clinical parameters. In patients with malignant pleural effusions, a pH of less than 7.3 is usually seen in those effusions present for several months and is associated with a lower glucose level and a higher white cell count and lactic dehydrogenase level. Results of cytologic study of the pleural fluid and pleural biopsy are often positive, there is poor response to sclerosing agents, and the prognosis is poor. A rheumatoid pleural effusion most often has a pleural fluid pH below 7.3. A pleural fluid pH below 6 is seen almost exclusively in esophageal rupture but rarely with empyemas, whereas a pleural fluid pH below 7 occurs in esophageal rupture, empyema, and rheumatoid pleural effusions. In pleural effusions secondary to congestive heart failure, the pH is almost always greater than 7.4 unless systemic acidemia coexists, in which case the pleural fluid pH is within 0.04 units of the simultaneous arterial pH. The major value of pleural fluid pH is to determine the need for chest tube drainage in parapneumonic effusions and to determine the response to sclerosing agents in patients with malignant pleural effusions. As with all diagnostic tests, the results should be interpreted in the context of other diagnostic tests of the pleural fluid and clinical aspects before diagnostic or therapeutic decisions are made.

Arthritis, Rheumatoid↗
PubMed1987

Preoperative medical consultation and evaluation of surgical risk.

Internists are frequently asked to assess the surgical risk of patients with various medical problems. Numerous recent prospective studies have defined specific risk factors for increased morbidity and mortality in the preoperative evaluation of surgical patients. Careful attention to such factors as age, type of operation and anesthesia, underlying pulmonary, hypertensive, cardiac, renal, hepatic, endocrine, and hematologic diseases, and nutritional status can reduce the complication rate and death rate in surgical patients if specific preoperative, operative, and postoperative therapeutic maneuvers are instituted. A comprehensive comparative analysis by the internist, surgeon, and anesthesiologist should be made on all high-risk surgical patients to improve their medical care.

Anesthesia↗
PubMed1987

Treatment of severe hypertension and hypertensive crises with nifedipine.

The calcium channel blocker nifedipine is an effective antihypertensive agent for the treatment of severe hypertension and hypertensive crises. It produces a prompt, predictable and consistent reduction in systemic arterial pressure with minimal adverse effects. The blood pressure reduction is inversely correlated with the pretreatment blood pressure level. Various nonparenteral administration forms-oral, sublingual, buccal and rectal-permit a versatile, noninvasive, cost-effective alternative to parenteral antihypertensive therapy and continuous hemodynamic monitoring. Blood pressure is reduced to the goal level in 98% of patients with a 10- to 20-mg dose of nifedipine. Hemodynamic changes are favorable and morbidity is uncommon.

Hemodynamics↗
PubMed1986

Treatment of hypertensive urgencies and emergencies with nifedipine.

The calcium channel blocker, nifedipine, is an effective antihypertensive agent for the treatment of hypertensive urgencies and emergencies. It produces a prompt, safe, predictable, and consistent reduction in systemic arterial pressure with minimal adverse effects. The reduction in blood pressure is inversely correlated with the pretreatment blood pressure level. Various nonparenteral administration forms (oral, sublingual, buccal, and rectal) permit a versatile, noninvasive, cost-effective alternative to parenteral antihypertensive therapy and continuous hemodynamic monitoring. The overall efficacy in reaching goal blood pressure approaches 98% with a 10 to 20 mg dose of nifedipine. Hemodynamic changes are favorable, and there is rarely any associated morbidity (severe hypotension) or mortality. The role of nifedipine in the treatment of hypertensive emergencies is promising, but further studies are needed to compare it to other approved emergency antihypertensive regimens.

Adult↗
PubMed1986

Calcified intracranial metastases from breast carcinoma with a therapeutic response to tamoxifen therapy.

A 66-year-old woman with a subacute onset of mild dementia and headaches was discovered to have multiple large, hyperdense lesions on cranial CT scan. Biopsy showed poorly differentiated adenocarcinoma with necrosis and dystrophic calcification, which represented an unusual initial manifestation of metastatic breast carcinoma after a seven-year disease-free period. Neurologic symptoms improved with tamoxifen therapy.

Adenocarcinoma↗
PubMed1986

Adverse effects of antihypertensive drug therapy on glucose intolerance.

Several antihypertensive drugs have an adverse effect on glucose tolerance that may partially or completely negate the beneficial effects of reducing blood pressure as it relates to the incidence of coronary heart disease and its complications. Diuretics (particularly high doses) and beta-blockers without intrinsic sympathomimetic activity have the greatest adverse effect on glucose intolerance. Central alpha-agonists, angiotensin-converting enzyme inhibitors, calcium channel blockers, and alpha-blockers do not adversely affect glucose and are preferred in diabetic hypertensive patients, selected hypertensive patients at risk for developing glucose intolerance, and probably most other patients with mild essential hypertension as initial and/or monotherapy compared with diuretics and beta-blockers.

Adrenergic alpha-Agonists↗
PubMed1986

Sodium and hypertension. A review.

Abnormal sodium metabolism may be critical in the causation of certain forms of hypertension, particularly salt-sensitive hypertension. Long-term restriction of sodium intake in patients at high risk for the development of hypertension may reduce the chances of established hypertension occurring later. These high-risk patients in whom subsequent hypertension may be prevented include normotensive patients with family histories of hypertension, elderly patients, black patients, and those with low-renin hypertension. Treatment of hypertension with moderate sodium restriction to 70 mEq/day will significantly reduce blood pressure in a large percentage of patients, particularly known salt-sensitive hypertensive patients. This degree of restriction is also an effective adjunctive therapy for patients receiving antihypertensive medications. There is convincing experimental, epidemiologic, and clinical evidence that moderate sodium restriction helps prevent and assists in the treatment of hypertension in those patients who are genetically predisposed to develop primary hypertension or who already have hypertension. There is no evidence that this degree of sodium restriction is harmful.

Animals↗
PubMed1986

Treatment of hypertensive emergencies and urgencies with oral clonidine loading and titration. A review.

Oral clonidine hydrochloride rapid titration or loading is a safe, effective method to control severe elevations of blood pressure in hypertensive crisis in many clinical situations. An initial oral dose of 0.1 to 0.2 mg of clonidine hydrochloride followed by hourly doses of 0.05 or 0.1 mg until goal blood pressure is attained that does not reduce perfusion to critical organs, or a total of 0.7 mg is given, will achieve a significant reduction in blood pressure in 93% of patients. A smooth, rapid, predictable reduction in blood pressure, patient comfort, lower overall cost, reduced requirement for close observation, intravenous lines, and hospitalization, and a small incidence of clinically significant side effects make oral clonidine rapid titration an attractive oral antihypertensive agent for patients with hypertensive urgencies and in some carefully selected patients with hypertensive emergencies. Immediate outpatient follow-up within 24 hours is mandatory in all patients who are not hospitalized to adjust the dose of antihypertensive medications.

Blood Pressure↗
PubMed1984

Shock. Diagnosis and management.

Recent investigations have underscored the great diversity in both the causes and manifestations of clinical shock. The emphasis has shifted toward more specific therapy when that has been possible. Pure vasoconstrictors have assumed a secondary therapeutic role, as volume replacement or expansion has become the initial management of shock. Agents, such as naloxone hydrochloride, corticosteroids, fructose diphosphate, amrinone and milrinone , and nonsteroidal antiinflammatory agents, while still experimental, offer improved understanding and management of the shock syndrome.

Blood Volume↗
PubMed1982

Clonidine hydrochloride.

Clonidine hydrochloride (Catapres), a potent antihypertensive agent, has been in clinical use since 1974 in the United States. Clonidine, an alpha-adrenergic receptor agonist, stimulates central alpha receptors in the depressor site of the vasomotor center of the medulla oblongata and hypothalamus, which diminishes efferent sympathetic tone to the heart, kidneys, and peripheral vasculature with a concomitant increase in vagal activity. Hemodynamic and renal effects include reduction in supine and erect blood pressure, heart rate, total peripheral resistance, plasma renin activity, and urinary aldosterone and catecholamine excretion, with little effect on resting cardiac output, response to exercise, and preservation of renal function. Clonidine alone produces a significant reduction in mean arterial pressure in all degrees of hypertension during acute and chronic administration, with little or no tendency toward tolerance or postural hypotension. Its antihypertensive potency is enhanced with the concomitant use of a diuretic or vasodilator, and it may be used in place of a beta blocker with equal efficacy in the diuretic plus vasodilator combination. Serious adverse effects are uncommon, with more than 93% of patients tolerating the drug well. Sedation and dry mouth, the most common adverse effects, are usually related to dose and duration and are minimized by gradually increasing the dose and by taking the major portion of the twice-daily schedule at bedtime. Clonidine may be safely given to patients with congestive heart failure, ischemic heart disease, obstructive lung disease, chronic renal insufficiency, and diabetes mellitus. Clonidine is one of the most versatile and effective agents presently available for the treatment of hypertension.

Antihypertensive Agents↗