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Pulse oximetry is now a widely available technology that provides easy and continuous reliable measurements of oxygen saturation, the percentage of O2 bound to Hb (SpO2). Pulse oximetry has become a standard monitoring not only in intensive care, but also in other clinical settings, although several factors can interfere with a correct reading, as low perfusion conditions, such as low cardiac output, vasoconstriction, hypothermia. We performed a prospective observational study in two groups of twenty-eight patients admitted to the ICU, in which we compared the values ​​obtained (SpO2) with digital and forehead pulse oximetry, with arterial oxygen saturation (SaO2) obtained from blood gas analysis (EGA). Comparison measurements into two distinct groups, though homogeneous might be a limitation of the study, but at the same time provide a representative picture of a polyvalent intensive care unit. The result was that both the values ​​obtained with digital and frontal pulse oximetry are accurate and reliable in comparison to EGA. In situations of hypoxia, the reliability of frontal pulse oximetry appears superior compared to digital oximetry.

This case report has the scope to review the etiology and pathophysiology of pneumomediastinum in severe blunt trauma, with a special interest to its more frequent origin: the Macklin effect. The Macklin effect is a pathophysiologic process characterized by the blunt traumatic alveolar ruptures, air dissection along bronchovascular sheaths, with the formation of blunt pulmonary interstitial emphysema, radiologic marker, until the formation of a pneumomediastinum. Its premature diagnostic acknowledgment is important in the managing of the blunt chest trauma.