Detection of arrhythmogenic cellular magnesium depletion in hip surgery patients

The use of high-dose magnesium infusions in critically ill and surgical patients is increasing. This practice is associated with considerable risk of toxicity, as no reliable criteria are currently available to detect significant intracellular magnesium depletion. We have evaluated, before and after surgery, 33 elderly patients with hip fracture, by 24-h Holter ECG monitoring, Doppler echocardiography and serum chemistry; lymphocyte magnesium was measured using atomic absorption spectrophotometry. The severity of ventricular arrhythmias increased, and serum and mononuclear magnesium concentrations decreased significantly after surgery. Decreases in either serum magnesium concentrations > 0.125 mmol litre-1 or cellular magnesium > 6 nmol mg- 1, but not serum or lymphocyte absolute magnesium concentrations, were associated with postoperative development of repetitive arrhythmias. Variations in serum magnesium concentrations correlated with intracellular decreases, and yielded good accuracy in predicting the postoperative worsening of arrhythmias. Thus perioperative differences in serum magnesium concentrations reflected intracellular variations and allowed us to identify patients with clinically relevant cellular magnesium depletion.      

Plasma renin activity in essential hypertension

Summary A study of the frequency distribution of plasma renin activity (PRA) in 123 patients with essential hypertension (EH) produced no evidence of a distinct subpopulation with low renin levels, whether the samples were taken from supine or upright patients. Applying an arbitraty classification criterion, however, low PRA levels were found in 30.1% of patients. There were no significant differences in mean blood pressure, 24-h sodium excretion, and age when groups with low, normal or high PRA levels were compared. The incidence of PRA hyporesponsiveness was similar in the three groups of patients, but increased with age. In the female there was a preponderance of low PRA levels. It is concluded that EH with low PRA levels is not a separate diagnostic entity and, when PRA is low in a hypertensive subject, the possible effects of age, blood pressure, and sex ought to be taken into account before other causes of low PRA are postulated.     

Hypertension in Primary Glomerulonephritis Without Renal Insufficiency

Hypertension is frequently present in glomerunephritis withoutrenal insufficiency but its pathogenesis is poorly understood.Eighty-five patients with glomerulonephritis and normal renalfunction, including 55 hypertensive patients, and 24 normalsubjects were studied to obtain data on the mechanisms responsiblefor hypertension. Plasma renin activity (PRA), plasma noradrenaline,total exchangeable sodium, and urinary prostaglandin E (PGE)were determined. Moreover, the autonomic nervous system wasexplored with the following tests: tilt test, diving reflex,lying down, and deep breathing tests. In 15 of the 30 normotensivepatients with glomerulonephritis, PRA was measured after theadministration of propranolol and then indomethacin. No significantdifferences were found in the mean values of PRA, plasma noradrenaline,total exchangeable sodium, urinary PGE, and autonomic nervoussystem behaviour between glomerulonephritis patients with andwithout hypertension or between hypertensive glomerulonephritispatients and control subjects. In many of the normotensive glomerulonephritispatients we found an elevated PRA that was normalised by propanololbut not by indomethacin. In summary, hypertension in glomerulonephritis is not associatedwith abnormalities in the sodium balance, with renin-angiotensinor with autonomic nervous system abnormalities. A renin hypersecretionseems to be present only in some normotensive patients withglomerulonephritis.     

Verapamil disposition and cardiovascular effects in elderly patients after single intravenous and oral doses

Summary Pharmacokinetics and pharmacodynamics of verapamil were studied in 11 elderly subjects (age=79.67±4.74 years) and in 11 middle-aged subjects (age=45±11.37 years) following intravenous (IV), single oral, and long-term oral administration.Plasma verapamil concentrations were determined using high-pressure liquid chromatography (HPLC). Twenty-four hour dynamic Holter electrocardiographic (ECG) recordings were employed to study heart rate (HR) and P-R interval.No difference in plasma half-life, distribution volume, body clearance, and area under the curve (AUC) was observed between the two groups after IV and oral verapamil administration.Blood pressure (BP) and HR were significantly reduced after verapamil IV administration in the elderly group only (p<0.05, p<0.01, respectively). After single and long-term oral administration, variable HR and BP responses were observed in both groups.The P-R prolongation following both IV and single oral doses exhibited a delay with respect to the peak plasma concentration, inducing a definite hysteresis loop. The slope of P-R variations (using a linear pharmacodynamic model) was greater in the elderly both after IV and single oral verapamil administration, but statistical significance was obtained only after the single oral dose (p<0.05). In the elderly group, after long-term oral administration, there was a significant prolongation of the P-R interval (p<0.0001) with respect to the corresponding time point of the 24-hour predrug period. Such variations in pharmacodynamic parameters in the elderly did not, however, cause any clinical problem.In conclusion, verapamil seems to be well tolerated in the elderly as well as in younger patients at similar dosages. However, its use in the elderly requires careful clinical evaluation.     

Left ventricular dysfunction: a clue to cognitive impairment in older patients with heart failure

OBJECTIVES—Cognitive impairment has been reportedin middle aged patients with end stage heart failure. This crosssectional study assessed the prevalence and determinants of cognitivedysfunction in older patients with mild to moderate heart failure.
METHODS—57 consecutive patients (mean age 76.7 years) with chronic heart failure underwent physical examination, bloodchemistry, urinalysis, chest radiography ECG, Doppler echocardiography,and the mini mental state examination (MMSE), mental deterioration battery, depression scale of the Center for Epidemiological Studies (CES-D), Katz activities of daily living, and instrumental activities of daily living 24 hours before hospital discharge.
RESULTS—MMSE scores <24 were found in 53% ofparticipants. The MMSE score was associated with left ventricularejection fraction according to a non-linear correlation, so thatcognitive performance was significantly lower in subjects with leftventricular ejection fraction 30%. The same pattern of correlationwas evidenced between left ventricular ejection fraction and both theattention sub-item of MMSE and the Raven test score. In a multivariatelinear regression model, after adjusting for age, sex, and aseries of clinical data and objective tests, both age (β=−0.30;P=0.038) and the natural log of left ventricular ejection fraction(β=0.58; P=0.001) were associated with the MMSE score.
CONCLUSION—Cognitive impairment in olderpatients with chronic heart failure is common, and independentlyassociated with lower left ventricular ejection fraction. Giventhe overwhelming incidence and prevalence of heart failure in olderpopulations, early detection of cognitive impairment in these subjectswith prompt, intensive treatment of left ventricular systolicdysfunction may prevent or delay a remarkable proportion of dementia inadvanced age.

     

ACE inhibition reduces proteinuria in normotensive patients with IgA nephropathy: a multicentre, randomized, placebo-controlled study

A multicentre, randomized, placebo-controlled study was performedin 39 adult patients with biopsy-proven IgA nephropathy withthe aim of comparing the effects of the ACE inhibitor fosinopriland placebo on proteinuria. All patients had normal blood pressureand normal renal function. Proteinuria ranged from 1.0 to 2.5g/24 h. After a 3-month run-in period, fosinopril and placebowere randomly administered in two 4-month sequences separatedfrom crossover treatment by a 1-month interval. The mean valuesof creatinine clearance did not change during either the placeboor the treatment sequences. The mean values of mean arterialpressure (MAP) were significantly lower during the fosinoprilsequence (90.4 ±9.0 mmHg) than in basal conditions (92.8± 9.1 mmHg) (P=0.034). The mean basal values of proteinuriawere 1.74 ±0.84 g/24 h. They were unchanged during theplacebo sequence (1.79 ±1.20) and fell to 1.37 ±0.98g/24 h after 4 months of fosinopril treatment. Using a multivariatestatistical analysis, the treatment effect by time on proteinuriawas significantly evident only in the fosinopril sequence (Wilkstest, P=O.O33). Changes in protein excretion were not correlatedwith changes in MAP, baseline plasma renin activity, and urinarysodium excretion. This controlled study shows that fosinoprilcan significantly reduce proteinuria even in normotensive patientswith IgA nephropathy. Obviously, the results of treatment withACE inhibitors on long-term renal prognosis remain to be elucidated.     

Perioperative Risks of Untreated Obstructive Sleep Apnea in the Bariatric Surgery Patient: a Retrospective Study

Background

The use of continuous positive airway pressure (CPAP) perioperatively in bariatric surgery patients with obstructive sleep apnea (OSA) has been controversial. Although studies have demonstrated that CPAP use is safe in bariatric patients, prior studies have not shown improvement in outcomes in these patients.

Methods

A retrospective review of patients who underwent bariatric surgery from 2005 to 2009 was performed. All patients underwent polysomnography preoperatively. Patient age, sex, BMI, comorbidities, polysomnogram data, type of bariatric procedure, length of hospital stay, and postoperative complications were reviewed. The Fisher exact test was used for statistical analysis.

Results

Among the 352 patients studied, 47 with apnea-hypopnea index (AHI) ≥5 did not receive CPAP postoperatively. A total of 7/47 (14.9 %) developed postoperative pulmonary complications. There were no non-pulmonary complications. Some 9/305 (2.95 %) with CPAP developed pulmonary complications. There were 26/305 patients with all-cause complications (8.52 %). The AHI was higher in the group receiving treatment. There was a statistically significant difference in pulmonary complications between patients with and those without treatment (p value 0.0002). The average length of stay was 3.0 and 3.2 days in treatment and comparison groups, respectively, a difference that did not reach statistical significance.

Conclusions

Patients who did not receive CPAP postoperatively developed more pulmonary complications than those with CPAP, suggesting that CPAP might be beneficial in decreasing pulmonary complications in patients undergoing bariatric surgery. However, further investigation is warranted to better delineate other risk factors due to small sample size in our study group.