No abstract

Pulmonary fat embolism occurs frequently after trauma but its functional significance is often unclear. To obtain direct evidence of lung damage caused by fat embolism we have measured changes in permeability of the alveolar-capillary interface. A permeability index was derived from the half time clearance from lung to blood (T-LB) of 99mTc DTPA introduced into the lung in a 1 ml bolus. Three groups ofrabbits were studied. Baseline Tw LB. did not differ significantly between groups. After intravenous injection of saline placebo in one group and of 300 mg/kg triolein in another group there was no change in permeability index. After intravenous injection of 100 mg/kg oleic acid in the third group there was an immediate change in T' LB from a monoexponential baseline 280 ± 20 min (SEM) to a multiexponential curve which was resolved into two components, one with a T'LB of 3-2 ± 0-6 min (SEM) and the other 39 5 ± 7-6 min (SEM). Statistically significant changes in alveolar-arterial Po2 difference, dynamic compliance, chest radiography, and postmortem lung water accompanied the changes in T'LB in this group. There were no significant changes in these variables in the placebo or triolein group. Histological studies of the lung tissue of these animals using the osmic acid stain for fat showed no fat in the placebo group, extensive fat embolisation which was densely stained in the triolein group and much less densely stained fat in the oleic acid group. Measurement of the permeability of the alveolar-capillary interface provides direct evidence of lung damage after oleic acid embolisation. There were no functional changes in animals with extensive embolisation with triolein.

1. To investigate the mechanisms of acute mountain sickness, 22 subjects travelled to 3100 m by road and the following day walked to 4300 m on Mount Kenya. Control measurements were made over 2 days at 1300 m before ascent and for 2 days after arrival at 4300 m. These included body weight, 24 h urine volume, 24 h sodium and potassium excretion, blood haemoglobin, packed cell volume, and symptom score for acute mountain sickness. In 15 subjects blood samples were taken for assay of plasma aldosterone and atrial natriuretic peptide. 2. Altitude and the exercise in ascent resulted in a marked decrease in 24 h urine volume and sodium excretion. Aldosterone levels were elevated on the first day and atrial natriuretic peptide levels were higher on both altitude days compared with control. 3. Acute mountain sickness symptom scores showed a significant negative correlation with 24 h urinary sodium excretion on the first altitude day. Aldosterone levels tended to be lowest in subjects with low symptom scores and higher sodium excretion. No correlation was found between changes in haemoglobin concentration, packed cell volume, 24 h urine volume or body weight and acute mountain sickness symptom score. 4. Atrial natriuretic peptide levels at low altitude showed a significant inverse correlation with acute mountain sickness symptom scores on ascent.

Beeley, J. M., Darke, C. S., Owen, G., and Cooper, R. D. (1974). Thorax, 29,[21][22][23][24][25]. Serum zinc, bronchiectasis, and bronchial carcinoma. Serum zinc levels were measured by atomic absorption spectrophotometry in 65 patients with proven bronchiectasis; the mean level was 93 jig/100 ml, while the levels in two groups of healthy control subjects were 88-6 and 92-7 j.g/100 ml respectively. The range of individual values was similarinall groups and the differences between the mean serum zinc levels of the two groups of control subjects and the mean level of the group of patients with bronchiectasis were small and did not attain significance at the conventional 0-05 level. In contrast, the mean level in bronchial carcinoma patients (75-9 gg/100 ml) was significantly less than in each of the other groups of subjects.Zinc sulphate was administered for six weeks on a double-blind cross-over basis to patients with bronchiectasis and, although serum zinc levels rose, no detectable clinical improvement resulted. No definitive evidence of zinc deficiency in bronchiectasis has been established.

In a party of 17 subjects who travelled together to 4,500 m, hypoxic ventilatory response (HVR) and maximum oxygen consumption (VO2max) were measured before departure. HVR was measured under constant and varying alveolar carbon dioxide tension (PACO2) conditions. VO2max was measured by both standard expired gas collection technique on a treadmill and using the "shuttle run" technique. On arrival at altitude, symptoms of acute mountain sickness (AMS) were scored daily for three days. There were no cases of severe AMS but half of the party had mild to moderate degrees of AMS. There was no correlation between AMS scores and HVR by either method of measurement or with VO2max measured by either method of measurement or with VO2max measured by treadmill or shuttle run.