Infant Flow Driver or single prong nasal continuous positive airway pressure: short-term physiological effects

The effectiveness of single prong nasal continuous positive airway pressure (CPAP) was compared with the Infant Flow Driver (IFD) in a crossover study in 20 neonates treated with ≤ 30% oxygen by nasal CPAP. They were randomized to the device used at the start of the study. Each infant was studied for four consecutive 2-h periods alternating between single prong nasal CPAP and the IFD. The FiO² from the IFD read 0.02 higher than the same setting on the ventilators used for single prong nasal CPAP. The IFD improved the mean (95% CI) of theFiO₂by 0.05 (0.02–0.08), p = 0:008. Taking into account the systematic error in the FiO² between the devices the real mean improvement in FiO₂ produced by the IFD was 0.03 (-0.005 to 0.06), p = 0:09. There were no significant differences in respiratory rate, heart rate, blood pressure or comfort score of infants during periods of single nasal prong CPAP compared with periods on the IFD.     

Variant angina due to deficiency of intracellular magnesium by anorexia nervosa

A 51-year-old man who had a past history of gastric resection for medically uncontrollable gastric ulcer has loss of appetite that recurs periodically. And he has frequently presented spontaneous angina early in the morning since 1984. He was diagnosed as having variant angina by the documentation of typical ST elevation during anginal attack and also by showing coronary artery spasm (#2 and #12) during hyperventilation on coronary arteriography. A large quantity of calcium blocking agents and nitrates could not improve his symptoms. Lack of intracellular magnesium by loss of appetite was suspected from a daily excretion of urine magnesium (5.3 mEq) and magnesium tolerance test (56.7%). To confirm the effect of magnesium administration, the second coronary arteriography was performed. After magnesium sulphate (80 mEq, hourly) was injected, coronary artery spasm could not be induced by ergonovine. And orally magnesium oxide, calcium blocking agents and nitrates were started. Anginal attack disappeared with increasing urine magnesium.     

An improved method of densitometry of red-free retinal nerve fibre layer photographs

The red-free negatives of 53 right eyes (30 normal eyes and 23 glaucomatous eyes) and 51 left eyes (32 normal eyes and 19 glaucomatous eyes) were analysed using two different image densitometry techniques. The first technique measured the density from rectangular sample areas, while the second measured density from sector-shaped sample areas which more closely follow the course of the nerve fibres in the retina.
Indices which measured the deviation of the data from a clinically determined normal 'gold standard' were calculated, and were used to determine the optimum sensitivity and specificity in separating normal from glaucomatous eyes.
There is a significant difference between the data from the normal and glaucomatous groups of eyes, when measured from the sector sample areas. The relative efficacy of this technique is also shown by the improved values of sensitivity (from 42%-70% to 70%-91%), although specificity remained fairly constant (from 66%-83% to 62%-88%).