EVALUATION OF OXYGEN EXTRACTION TENSION PX INACUTE RESPIRATORY FAILURE IN CHILDREN

Nguyen Dinh Hai

Pediatric Intensive Care Unit, Nhan Dan Gia Dinh Hospital, Vietnam

Objectives: A prospective study was carried out to: 1) Evaluate the change of Pxin the comparison with that of PaSO₂, Shunt and AaDPO₂, Shunt and AaDPO₂, in the acute respiratory failure. 2) Follow up the response in the treatment of acute respiratory failurre.

Patients and methods: 2 groups of patients from 1 to 15 years of age (cardiac and anemic patients are excluded); -Group 1:40 patients with acute respiratory failure the due to pulmonary diseases. –Group 2:40 healthy children. All patients with acute respiratory failure received oxygen and an adequate management.

Results: 1) In slightly acute respiratory failure (ARF) (10 cases): most Px is within the normal range, a few cases increase slightly where as PaO₂ decreases ro 90-80mmHg, total Shunt elevates to 8-15%, AaDPO₂ increases to 11-20 mmHg. 2) In moderately acute respiratory failure (ARF) (20 cases), most Px increases slightly. While PaoO₂ decrease ro 80-60 mmHg, Shunt increase to 16-35% AaDPO₂, increase to 21-40mmHg, 3) In severely acute respiratory failure (ARF) (10 cases): All of Px decrease moderately, the PaO₂ decrease below 60mmHg, Shunt increase above 35%, AaDPO₂ increase above 40 mmHg.

Conclusion: Oxgen extraction tension Px is an index that reflects the combined effect of the arterial PO₂ value, the Oxygen content and Hb Oxygen affinity: 1) Inslightly ARF, Px remain the same or decrease slightly, Px decrease significantly only in moderate and severely ARF. Whereas PaO₂, total Shunt and AaDPO₂ change more significantly substantially, 2) When ARF is over, Px return to normal range more slowly than PaO₂, Shunt and AaDPO₂. A lowered oxygen extraction tension Px is a high risk factor.

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