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Biomedical subjects

M M Salem

Publications and source records attributed to M M Salem.

17 recordsLinked to original sources
PubMed2000

Predictors of left ventricular outflow obstruction following single-stage repair of interrupted aortic arch and ventricular septal defect.

This study looked at echocardiographic predictors of left ventricular outflow obstruction after primary neonatal repair of interrupted aortic arch and ventricular septal defect. Results of this study indicate that the only significant independent predictor of left ventricular outflow obstruction is aortic valve diameter; all patients with an aortic valve diameter <4.5 mm (Z score <-5) subsequently developed obstruction, whereas patients with annuli >4.5 mm (Z score >-5) remained free from obstruction.

Abnormalities, Multiple↗
PubMed2000

Treatment of hypertension in the hemodialysis patient: beneficial or not?

Hypertension is common in the hemodialysis population. Although hypertension in the general population has been shown to reduce survival and to accelerate atherosclerosis, leading to serious cardiac and cerebrovascular morbidity, its effects are less clear in those undergoing dialysis. This review focuses on recent studies showing a favorable outcome in hypertensive hemodialysis patients when compared with those with lower blood pressure. The possible explanations for this paradoxic relationship are examined, and practical suggestions are given for the management of hypertension in the patient undergoing hemodialysis. We also present information on the morbiditiy associated with hypertension in the hemodialysis population.

Comorbidity↗
PubMed2000

Atrial natriuretic factor in oliguric acute renal failure. Anaritide Acute Renal Failure Study Group.

Atrial natriuretic peptide (ANP), an endogenous hormone synthesized by the cardiac atria, has been shown to improve renal function in multiple animal models of acute renal failure. In a recent multicenter clinical trial of 504 patients with acute tubular necrosis (oliguric and nonoliguric), ANP decreased the need for dialysis only in the oliguric patients. In the present study, 222 patients with oliguric acute renal failure were enrolled into a multicenter, randomized, double-blind, placebo-controlled trial designed to assess prospectively the safety and efficacy of ANP compared with placebo. Subjects were randomized to treatment with a 24-hour infusion of ANP (anaritide, 0.2 microgram/kg/min; synthetic form of human ANP) or placebo. Dialysis and mortality status were followed up for 60 days. The primary efficacy end point was dialysis-free survival through day 21. Dialysis-free survival rates were 21% in the ANP group and 15% in the placebo group (P = 0.22). By day 14 of the study, 64% and 77% of the ANP and placebo groups had undergone dialysis, respectively (P = 0.054), and 9 additional patients (7 patients, ANP group; 2 patients, placebo group) needed dialysis but did not receive it. Although a trend was present, there was no statistically significant beneficial effect of ANP in dialysis-free survival or reduction in dialysis in these subjects with oliguric acute renal failure. Mortality rates through day 60 were 60% versus 56% in the ANP and placebo groups, respectively (P = 0.541). One hundred two of 108 (95%) versus 63 of 114 (55%) patients in the ANP and placebo groups had systolic blood pressures less than 90 mm Hg during the study-drug infusion (P < 0.001). The maximal absolute decrease in systolic blood pressure was significantly greater in the anaritide group than placebo group (33.6 versus 23.9 mm Hg; P < 0.001). This well-characterized population with oliguric acute renal failure had an overall high morbidity and mortality.

Adult↗
PubMed1999

Hypertension in the haemodialysis population: any relationship to 2-years survival?

BACKGROUND: Few studies have quantified the effect of hypertension on survival in the haemodialysis (HD) population. We have previously reported lack of adverse effect of hypertension on 1-year mortality in a cohort of 649 haemodialysis patients (Am J Kidney Dis 1996; 28: 737-744). We report here the effect of hypertension on 2-year survival in the same cohort of patients. METHODS: We reviewed the complete computerized files on 649 HD patients enrolled in 10 haemodialysis centres in the state of Mississippi, USA. One-month dialysis records for each patient from mid-October 1994 to mid-November 1994 were reviewed. Predialysis mean arterial pressure was calculated as immediate predialysis diastolic pressure plus one-third the difference between systolic and diastolic pressure. Patients were classified as hypertensive if their average pre-MAP was more than 114 mmHg or they were receiving antihypertensive drugs during the study period. Normotensives had a pre-MAP < 114 and were not receiving any antihypertensives. We followed these patients for 2 years to determine their survival and the effect of their BP status, as determined in October 1994, on 2-year mortality. RESULTS: In univariate analysis, hypertension was associated with improved 2-years survival (relative risk 0.64, P=0.08 compared to normotensives). Furthermore, among the hypertensives, good blood pressure control (less than 140/90) was associated with increased relative risk of death at 2 years (RR 1.86, P=0.004). In multivariate analysis, taking age, race, serum albumin, and diabetic status into consideration, there was a 27% reduction in mortality among hypertensives compared to normtensives (RR 0.73, P=0.06). Other factors of significance in multivariate analysis were age (RR 1.03/year, P=0.02), serum albumin (RR 0.36/g, P<0.0001), diabetes mellitus (RR 1.35, P=0.07), and race (RR 0.64, P=0.05). CONCLUSIONS: Our study suggests that hypertension has no adverse effect on survival at 2 years in the haemodialysis population.

Analysis of Variance↗
PubMed1998

Comparison of laparoscopic and open cholecystectomy at Prince Abdulrahman Al Sudairy Hospital, Saudi Arabia.

The initial 300 patients whose symptomatic cholelithiasis was managed by laparoscopic cholecystectomy (LC) were matched to and compared with 300 patients managed by open cholecystectomy (OC) during the 30 months prior to the introduction of LC. Of the 300 LC attempted 292 (97.3%) were successful with conversion to OC rate of 2.7%. Besides the obviously better cosmetic results, LC patients had less post operative pain, mean doses of opiates needed 0.01 versus 5 for OC (p < 0.0001), were discharged earlier from the hospital, mean 3.1 days versus 8 days for OC (p < 0.001) and had less postoperative complications 4% versus 11% for OC. We conclude that not only is LC a better operation than OC, but also that in the regional referral centres such as ours, LC can safely supplant OC as the preferred modality for the management of symptomatic cholelithiasis.

Adolescent↗
PubMed1997

Hyperparathyroidism in the hemodialysis population: a survey of 612 patients.

There are no epidemiologic studies documenting the prevalence of hyperparathyroidism in the US hemodialysis population. We looked at a random sample of 612 hemodialysis patients enrolled in 10 outpatient dialysis units in Mississippi. Fifty percent of the patients surveyed had an intact serum parathyroid hormone (PTH) level more than three times normal (mean, 622 pg/mL). Another 25% had a less than normal PTH level (mean, 33 pg/mL), suggesting adynamic bone disease. Abnormal serum calcium was also common. Seventeen percent of patients were hypocalcemic and 14% were hypercalcemic. These high point prevalences occurred despite widespread use of calcium supplements and/or vitamin D (used in 90% of the patients surveyed). Black patients tended to have a lower serum calcium and higher PTH level than white patients. We also found that diabetic patients are less likely to have an elevated PTH level than nondiabetic patients. Elevated serum phosphorus was the most important factor correlating with the development of secondary hyperparathyroidism. Causes of inadequate control of hyperparathyroidism in this population require further study.

Bicarbonates↗
PubMed1997

Acidosis and coma after hemodialysis.

Ethylene glycol poisoning is a rare yet potentially fatal illness seen most commonly in association with ingestion by alcoholics or in suicide attempts. It is characterized by an elevated anion gap metabolic acidosis, osmolal gap, calcium oxalate crystals in the urine, and a well-defined clinical picture. Prompt treatment is crucial because effective intervention can prevent the neurologic, cardiac, pulmonary, and renal sequelae associated with ethylene glycol poisoning. Hemodialysis offers rapid clearance of ethylene glycol and its toxic metabolites. In this article, the case of a hemodialysis patient who suffered contamination of the dialysate solution with ethylene glycol, leading to altered mental status, coma, and severe anion gap metabolic acidosis, is reported. Despite prolonged dialysis and correction of the acidosis, the patient remained comatose and subsequently died.

Acidosis↗
PubMed1997

Effects of one year of hemodialysis on weight and blood pressure in 434 patients.

Excess volume is thought to be the major mechanism leading to hypertension in the hemodialysis population. Blood pressure measurements and volume parameters were obtained in 434 hemodialysis patients in 1994 and compared to their 1993 data. Equal numbers of patients were receiving antihypertensive treatment in both 1993 and 1994. The predialysis mean arterial pressure (pre-MAP) did not significantly change after 1 year of dialysis. The lack of change in blood pressure was evident in those who either lost or maintained body weight. There was no correlation between changes in interdialytic weight and changes in pre-MAP over 1 year. Volume sensitivity (described as the percentage decrease in blood pressure immediately after dialysis) was not different in 1993 from 1994. We conclude that irrespective of weight changes, the average hemodialysis patient does not show a significant change in blood pressure (BP) after 1 year of dialysis. This lack of improvement was evident regardless of age, sex, race, dialysis duration, or etiology of end-stage renal disease.

Adult↗
PubMed1996

Hypertension in the hemodialysis population: any relation to one-year survival?

Few studies have quantified the effect of hypertension on survival in the hemodialysis population. We report the effect of hypertension on 1-year survival in 649 hemodialysis patients (89% black). In univariate analysis, hypertension was associated with improved 1-year survival (relative risk [RR], 0.48; P = 0.002 compared with normotensive patients). This effect of hypertension was mostly caused by the associated antihypertensive treatment because untreated hypertensive patients had survival rates equal to normotensive patients (RR, 0.87; P = 0.70). On the other hand, treated hypertensive patients fared better than normotensive patients (RR, 0.41; P = 0.0006). This was also true in multivariate analysis, in which antihypertensive treatment was associated with reduced RR (RR, 0.55; P = 0.02) whereas the level of blood pressure per se was insignificant (RR, 0.99; P = 0.63 per 1 mm Hg increase in predialysis mean arterial pressure). Other factors of significance in multivariate analysis included age (RR, 1.03/y; P = 0.0004), serum albumin (RR, 0.38/g; P = 0.002), and diabetes mellitus (RR, 1.58; P = 0.06). Our study suggests that antihypertensive treatment has a favorable effect on survival in the hemodialysis population irrespective of the level of blood pressure control.

Antihypertensive Agents↗
PubMed1995

Hypertension in the hemodialysis population: a survey of 649 patients.

Accurate information on prevalence and status of blood pressure control among US hemodialysis patients is lacking. We have surveyed the status of blood pressure control in 649 hemodialysis patients (89.8% black) from 10 dialysis units in Mississippi. Our results show a hypertension prevalence of 72% (hypertension defined as mean arterial pressure prior to dialysis session > or = 114 mm Hg). This mean arterial pressure did not differ among black patients compared with white patients (P = 0.51). The majority of hypertensive patients (80%) had elevation of both systolic and diastolic blood pressure. Isolated systolic hypertension was present in only 20% of hypertensive patients and was not different between black and white patients (P = 0.10). Three hundred eighty-one patients (58.7% of the total population and 81.5% of the hypertensive patients) were receiving antihypertensives. Age was the only significant factor that correlated with blood pressure: older patients (> 65 years) had lower blood pressure (P < 0.0001). Race, time on dialysis, etiology of end-stage renal disease, adequacy of dialysis, and several excess volume parameters had no influence on the blood pressure level. Treated hypertensive patients had a predialysis mean blood pressure only 3 mm Hg less than the untreated hypertensive patients. No differences were found among four classes of antihypertensives with regard to the degree of blood pressure control. Patients with hypertension requiring more than one antihypertensive did not achieve a lower blood pressure than the untreated patients. There was no correlation between use of antihypertensives and the magnitude of decrease in blood pressure after dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Potassium adaptation in hypothyroidism: changes in transport adenosinetriphosphatases.

To evaluate whether hypothyroidism alters the adaptive responses of renal transport adenosine-triphosphatases (ATPases) to modifications in dietary K content, we examined the activities of Na-K pump and H-K pump in hypothyroid rats under basal conditions and after dietary K changes. Hypothyroidism led to a decline in Na-K pump activity in all three nephron segments examined [proximal convoluted tubule from 2,333 +/- 103 to 1,099 +/- 32, medullary thick ascending limb from 4,344 +/- 119 to 1,613 +/- 61, and cortical collecting tubule (CCT) from 1,133 +/- 45 to 640 +/- 38 pmol.mm-1 x h-1; all P < 0.01 vs. euthyroid] along with morphological changes manifest in a decrease in tubule diameter. K loading led to an increase in Na-K pump activity in the CCT of both euthyroid (from 1,133 +/- 45 to 2,269 +/- 74, pmol.mm-1 x h-1, P < 0.01) and hypothyroid (from 640 +/- 38 to 1,118 +/- 67 pmol.mm-1 x h-1, P < 0.01) animals. Furthermore, in euthyroid rats, 3 wk of K depletion led to a major increase in H-K pump activity in both the CCT (from 203 +/- 14 to 331 +/- 22 pmol.mm-1 x h-1, P < 0.01) and medullary collecting tubule (MCT, from 137 +/- 9 to 210 +/- 14 pmol.mm-1 x h-1, P < 0.01). Hypothyroidism was associated with a decline in H-K pump activity in the CCT and MCT (to 94 +/- 6 and 55 +/- 5 pmol.mm-1 x h-1, respectively; both P < 0.01 vs. euthyroid).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Gaps in the anion gap.

OBJECTIVE: To review limitations of the use of serum anion gap in clinical practice. DATA SOURCES: Original reports and reviews. STUDY SELECTION: Sources containing the most recent pertinent information. DATA SYNTHESIS: Theoretical and practical limitations beset the use of serum anion gap. Awareness of these limitations reduces but does not eliminate wrong diagnoses based on the anion gaps. CONCLUSIONS: Serum anion gap has a limited value in the differential diagnosis of acid-base disorders and can be misleading.

Acid-Base Equilibrium↗
PubMed1991

Extrarenal potassium tolerance in chronic renal failure: implications for the treatment of acute hyperkalemia.

The role of extrarenal potassium homeostasis is well recognized as a major mechanism for the acute defense against the development of hyperkalemia. The purpose of this report is to examine whether or not the various mechanisms of extrarenal potassium regulation are intact in patients with end-stage renal disease (ESRD). The available data suggest that with the development of ESRD and the uremic syndrome there is impaired extrarenal potassium metabolism that is related to a defect in the Na,K-adenosine triphosphatase (ATPase). The responsiveness of uremic patients to the various effector systems that regulate extrarenal potassium handling is discussed. Insulin is well positioned to play an important role in the regulation of plasma potassium concentration in patients with impaired renal function. The role of basal insulin may be even more important than previously appreciated, since somatostatin infusion causes a much greater increase in the fasting plasma potassium in rats with renal failure than in controls. Furthermore, stimulation of endogenous insulin by oral glucose results in a greater intracellular translocation of potassium in uremic rats than in controls. Under at least two common physiologic circumstances, feeding and vigorous exercise, endogenous catecholamines might also act to defend against acute increments in extracellular potassium concentration. However, it is important to appreciate that the response to beta 2-adrenoreceptor-mediated internal potassium disposal is heterogeneous as judged by the variable responses to epinephrine infusion. Based on the evidence presented in this report, a regimen for the treatment of life-threatening hyperkalemia is outlined. Interpretation of the available data demonstrate that bicarbonate should not be relied on as the sole initial treatment for severe hyperkalemia, since the magnitude of the effect of bicarbonate on potassium is variable and may be delayed. The initial treatment for life-threatening hyperkalemia should always include insulin plus glucose, as the hypokalemic response to insulin is both prompt and predictable. Combined treatment with beta 2-agonists and insulin is also effective and may help prevent insulin-induced hypoglycemia.

Acute Disease↗
PubMed1991

Myocardial oxygen supply/demand relations during phenylephrine infusions in dogs.

Experiments were performed on 14 fentanyl-pentobarbital-anesthetized dogs to assess changes in myocardial oxygen supply/demand relations during intravenous infusions of phenylephrine (2.8 micrograms.kg-1.min-1). Myocardial blood flow was measured with radioactive microspheres. Myocardial oxygen and lactate extraction were determined. Myocardial oxygen consumption was calculated with the Fick equation. In series 1, measurements were obtained during phenylephrine-induced pressor responses. In series 2, measurements were obtained with aortic pressure maintained constant with an extracorporeal reservoir during phenylephrine infusion, so that coronary vasomotor responses could be assessed in the absence of increases in ventricular afterload and perfusion pressure. In series 1, the phenylephrine-induced increase in mean aortic pressure (+42%) was accompanied by proportional (60%) increases in myocardial blood flow and myocardial oxygen consumption and with no change in the endocardium-to-epicardium flow ratio, oxygen extraction, coronary sinus oxygen tension and oxygen saturation, or myocardial lactate extraction. In series 2, phenylephrine infusion caused a transmurally uniform 15% decrease in myocardial blood flow combined with a 10% decrease in myocardial oxygen consumption. The coronary arteriovenous oxygen difference increased modestly (+5%), resulting in small decreases in coronary sinus oxygen tension and oxygen saturation, whereas lactate extraction was unaffected. The present findings suggest that phenylephrine has a direct vasoconstrictor effect in the coronary circulation that is weak and completely overridden by metabolic autoregulatory mechanisms in response to pressure-induced augmentations in cardiac workload. The authors conclude that the myocardium is not at risk when phenylephrine is used to treat hypotension in patients with adequate cardiac function and coronary vasodilator reserve.

Anesthesia, Intravenous↗