: Prolonged prone positioning increases IOP, choroid layer thickness, and optic nerve diameter independent of anesthetics and intravenous fluid infusion and 4 degrees of table inclination (15 cm of head to foot vertical disparity) may not attenuate these effects.

ABSTRACT. Our previous cross-sectional study of paKco, diffusion constant for carbon monoxide, or D L o tients with thalassemia major suggested progressive lung corrected for alveolar volume changes characterized by low total lung capacity, hypox-VC, vital capacity emia, and elevated transfer factor for carbon monoxide.TLC, total lung capacity We reevaluated nine of the patients for three reasons: 1) TM, thalassemia major to determine the relationship of the previous findings to the immediate effects of blood transfusion; 2) to assess the longitudinal progression of the lung changes; and 3) to evaluate the effect of splenectomy on-lung volume changes in these patients, all of whom underwent splenectomy in the interval between the two studies. We found that during the 5-to 6-yr period between studies total lung capacity had decreased significantly ( p < 0.05) from a mean 86% predicted to a mean 79% predicted. However, vital capacity increased significantly ( p < 0.05) from a mean 81% predicted to 88% with no significant change in functional residual capacity. There was no significant immediate effect of transfusion on total lung capacity, vital capacity, or functional residual capacity. However, the diffusion constant for carbon monoxide increased significantly ( p < 0.005) immediately following transfusion and there was a positive correlation between the increase and the amount of blood transfused (r = 0.74, p < 0.05). Arterial oxygen saturation was below 95% in five of eight patients and increased significantly with transfusion ( p < 0.05). We conclude: 1) thalassemia major and/or its treatment is associated with hypoxemia and a progressive reduction in total lung capacity. 2) Despite the progressive reduction in total lung capacity, splenectomy in patients with thalassemia major increases expiratory reserve volume and thereby increases vital capacity.3) The previous finding of elevated Kco carbon monoxide is explained quantitatively as a transient effect caused by blood transfusion. 4) Transfusion in patients with thalassemia major without overt signs of cardiac failure is usually associated with a transient increase in arterial oxygen saturation. (Pediatr Res 20: 20-23, 1986) Abbreviations DCOsb or DLCO, single breath diffusing capacity for carbon monoxide corrected for Hb concentration by the formula of Cotes et al. (6) In a previous study conducted in our laboratory (I), 17 patients with TM revealed a constellation of findings, including low lung volumes, increased maximum lung recoil, low static and dynamic compliance, elevated G o , and hypoxemia. Because the previous study of pulmonary function was conducted immediately after transfusion, the major purpose of the present study was to separate the immediate effects of transfusion from the natural history or long-term progression of the disease. Thus we performed studies of pulmonary function before and immediately after transfusion in patients with TM.Nine of the patients who participated in the first study were available for the current investigation....

Noninvasive exercise testing was used to assess gas exchange in 13 patients age 6-25 yr who had undergone Fontan procedures for tricuspid atresia, five of whom had preexisting Glenn shunts. The results were compared to 28 age- and sex-matched controls. Oxygen saturation was measured by ear oximetry at rest and after exercise. Ventilation, oxygen consumption (VO2), carbon dioxide production (VCO2), and heart rate were measured during progressive exercise. The ventilatory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2), mixed expired pCO2 (PECO2) end-tidal pCO2 (PETCO2), and dead space to tidal volume ratio (VD/VT) were determined during steady state exercise on a cycle ergometer. Heart rate was higher for VO2 by 15% (p less than 0.02) and ventilation was higher for both VO2 (by 37%, p less than 0.001) and VCO2 (by 27%, p less than 0.002) in the patients than the controls. Mean VE/VO2 was 35.4 +/- 7.8 (SD) compared to 25.8 +/- 3.1 (p less than 0.001) and mean VE/VCO2 was 41.7 +/- 9.0 compared to 31.6 +/- 4.3 (p less than 0.001). Mean PECO2 was 21.4 +/- 4.4 torr with controls at 27.9 +/- 3.8 (p less than 0.001) and mean PETCO2 was 33.0 +/- 5.3 torr compared to 40.0 +/- 3.3 (p less than 0.001). The patients had a mean oxygen saturation of 92 +/- 5% at rest and abnormal saturation after exercise (87 +/- 9, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

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