[Nocturnal hypoxemia after abdominal surgery: associated factors and usefulness of oxygen therapy]

Postoperative nocturnal hypoxemia (PONH) is a main factor in the genesis of respiratory, cardiac and neurologic complications after surgery.

To describe the phenomenon of PONH after elective laparoscopy and laparotomy, and to evaluate the usefulness of oxygen therapy in its prevention.

Fifteen elective patients (6 M, 9 F, 51 +/- 8 years old) scheduled for laparotomy (n = 8) or laparoscopy (n = 7) were studied. Ventilatory parameters and pulse oximetry were measured pre and postoperatively. Patients were randomly assigned to receive oxygen by nasal cannula either during the first or the second postoperative night.

PONH (SatO2 < 85) developed in seven patients (47%), of which four had undergone laparoscopic surgery. PONH was more frequent in mildly obese patients and those presenting preoperative hypoxemia (p = 0.03). Peak Flow was lower in patients presenting PONH (p = 0.04). In five patients, PONH was associated with significant tachycardia. Oxygen administration was associated with a higher SatO2 and prevented PONH in 6/7 patients.

PONH is a common event in patients older than 40 years scheduled for open or laparoscopic abdominal surgery, and develops more frequently in those with preoperative nocturnal hypoxemia and greater ventilatory impairment. PONH can be prevented, most of the time, with oxygen administration.