Ischaemia-modified albumin (IMA) is a marker of the release of reactive oxygen species (ROS) during hypoxaemia. In elite divers, breath-hold induces ROS production. Our aim was to evaluate the kinetics of IMA serum levels during apnea. Twenty breath-hold divers were instructed to perform a submaximal static breath-hold. Twenty non-diver subjects served as controls. Blood samples were collected at rest, every minute, at the end of breath-hold, and 10 min after recovery. The IMA level increased after 1 min of breath-hold (p < 0.003) and remained high until recovery. Divers were separated into 2 groups: subjects who held their breath for less than 4 min (G-4) and those who held it for more than 4 min (G+4). After 3 min of apnoea, the increase of IMA was higher in the G-4 group than in the G+4 group (p < 0.008). However, at the end of apnoea, the IMA level did not differ between groups. If IMA level was globally correlated with the apnoea duration, it is interesting to note that the higher IMA level was not found in the best divers. Similarly, if arterial blood oxygen saturation (SpO2) was globally inversely correlated with apnoea duration, the lowest SpO2 at the end of breath-hold was not found in the divers that performed the best apnoea. We concluded that these divers save their oxygen. The IMA level provides a useful measure of resistance to hypoxaemia.

Despite differences in their components, the two HMEFs that were tested achieved similar performances in terms of humidification and heating of inspired gases. Only one episode of endotracheal tube occlusion was detected, and very few patients (three in each group) had to be switched to an active heated humidifier. No difference was observed either in the rate of tracheal colonization or of ventilator-associated pneumonia. These data show that the Humid-Vent Filter Light and the Clear ThermAl HMEFs are suited for use with ICU patients.

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