Biomedical subjects
Publications and source records attributed to P Millman.
This evaluation compared the pressure support qualities of three mattresses by measuring the interface pressures using 20 subjects. The results indicate that the Pegasus Airwave mattress had significantly higher readings than Quattro DC2000 (p = 0.021, 95% confidence level) and the Nimbus II (p = 0.009, 99% confidence level) but that there is no significant difference between interface pressures for the Quattro DC2000 and the Nimbus II.
In this study, three mattresses were evaluated to assess their effectiveness in relation to the pain and discomfort experienced by 40 patients with neurological disorders who had Waterlow scores > or = 15 and required pressure support. The results indicate that one mattress (the Quattro DC2000) performed significantly better than the other two (Nimbus II and Pegasus Airwave).
The association between steady-state serum digoxin concentrations and control of ventricular response rate (VRR) was studied in 53 consecutive patients with atrial fibrillation. Decreases in VRR were significantly correlated with serum digoxin (rs = -0.22, P less than 0.05). Clinical responses were appropriate to serum digoxin concentrations in 37 patients (69.8%) and were inappropriate in 16 (30.2%) (P less than 0.05). Complicating clinical factors were present in all eight patients with inappropriate responses to therapeutic serum digoxin (0.5 to 2.0 ng/ml) (P = 0.046), but were also found in many patients with appropriate responses and thus could not serve to differentiate between the two categories. Digitalis intoxication occurred in one of the three patients with a concentration of serum digoxin greater than 2 ng/ml (P = 0.056). In 30% of our patients with atrial fibrillation, monitoring of serum digoxin was of value in identifying inappropriate therapeutic responses indistinguishable by clinical means and in defining the subgroup of refractory cases, which allows the prevention of digitalis intoxication.
Steady-state serum quinidine concentrations were monitored in 24 patients with acute myocardial infarction who were on a 1,300-mg daily dosing regimen. Mean serum concentrations spanned the therapeutic range, from 2 to 6 microgram/ml in 21 patients. In no patient was the level of 7 microgram/ml exceeded. Mean levels were similar in patients with congestive heart failure [3.6 +/- 1.5 (SD) microgram/ml] as in those free of failure (3.2 +/- 1.3 microgram/ml), and did not vary with impairment of renal function. There was a significant correlation between mean individual serum quinidine concentrations and the rate-normalized QT interval prolongation (r = 0.54, P less than 0.01); however, variability of the response was high. Variability of the mean serum quinidine levels among individuals was 41%. Variability within individual patients was only 18%. In the individual patient receiving prophylactic oral quinidine therapy, monitoring serum quinidine levels appears to be an accurate, reproducible and pharmacologically significant guideline to therapy.
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Steady state serum concentrations of digoxin were determined repeatedly in 34 infants with congenital heart disease. Simultaneous measurements of renal clearances of digoxin, creatinine and urea were obtained in 29 of the subjects. Serum digoxin concentrations were markedly higher in children under the age of 3 months than in those over this age, despite equal weight--adjusted 24 h doses. This finding was explained by a very rapid increase in renal digoxin clearance in the first 3 months--32 +/- 7 ml/min/1.73m2 at 1 week to 65.6 +/- 30 at 3 months. The subsequent increase in digoxin clearance was much slower, e. g. to 87.7 +/- 43 ml/min/1.73m2 at 12 months. Renal clearance of digoxin was equally well correlated with creatinine clearance (r = 0.87) as with urea clearance (r = 0.83), but it exceeded that of creatinine in all age groups. The findings indicate that both glomerular and tubular function is involved in the renal elimination of digoxin in young children, and that development of renal elimination of the drug parallels that of the maturation of renal function in the early months of life. The neonate and infant with congestive heart failure display impaired ability to eliminate digoxin. The impairment lessens rapidly with the development of renal function over the first 3 months of life. Diminished doses of digoxin should be advocated in this age group if therapeutic serum concentrations of the drug are to be maintained and toxicity avoided.
Steady state serum digoxin concentrations were determined in 34 neonates and infants receiving standard maintenance doses of the drug. Digitalis intoxication, diagnosed by ECG criteria, occurred in four of 13 patients with a serum concentration above 2 ng/ml and not in any of 21 subjects with a serum digoxin concentration below this level. This association was found to be significant. It seems that the concept of increased tolerance to digoxin hitherto ascribed to infants is not tenable and that the monitoring of serum digoxin concentration is essential to treatment in this age group.
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