Sex-linked differences in pulse oxymetry

The difference between genders has generated increasing interest in recent years. It is well known that women and men show differences in their respiratory system: different red blood cell counts, haemoglobin and 2,3-diphosphoglycerate plasma concentrations. Recently, further differences have been found in the ventilatory response to hypoxia and exercise and the evolution of some respiratory illnesses. In this study it was found that during rest at sea level, the haemoglobin oxygen saturation, as measured by pulse oxymetry, is slightly higher in women than in men (98.6 (SD 1.1)% versus 97.9 (SD 0.9)%; p = 0.001). These findings are consistent with other studies, which found gender differences in the transcutaneous or tissue PaO(2). The difference in oxygen saturation is not related to differences in ventilation. The disparity is modest and does not seem to produce great differences in the oxygen content of arterial blood, but combined with the different affinity of haemoglobin for oxygen or different metabolic rate, may play a role in the course of elite competition sports, high altitude ascents or the evaluation of critically ill patients. Further studies are needed to establish the degree, extent and clinical importance of these differences in the saturation of haemoglobin.

Changes in blood ammonia and lactate levels during a triathlon race

Blood ammonia and lactate concentrations were analyzed in 7 volunteer male athletes before and immediately after each segment of an endurance triathlon. The purpose of this study was to examine the effects of triathlon on ammonia and lactate blood levels and the possible correlation between both in each different event. Concentrations of blood ammonia were increased after each of the three segments, reaching a peak after the 40 km bicycle ride. Concentrations of blood lactate were also increased over baseline. However, there was a higher increase after the 1.4 km lake swim, than after the 40 km bicycle ride or after the 10 km run. No correlation was found between the levels of ammonia and lactate, suggesting that ammonia and lactate follow different metabolic patterns.

Respiratory gas exchange using a triaxial alveolar gas diagram

A triaxial alveolar gas diagram to depict fractional concentration of oxygen, carbon dioxide and nitrogen is described, in which the R = 1 line is always implicit. Although it is not claimed that this representation leads to new insights into respiratory physiology, a method of plotting on a triaxial coordinate system has been found to be well suited to many applications when a direct display of fractional nitrogen concentration is required.