Preoperative lung function tests as a predictor for atelectasis in morbidly obese patients during anesthesia

• Rationale: Pulmonary function is regularly impaired during general anesthesia and paralysis in morbidly obese patients. The aim of this study was to compare preoperative lung function with the alterations in respiratory function after induction of anesthesia in patients with BMI > 40 kg/m2.Methods: 23 women and 7 men (38 ± 9 years, (mean ± SD)), with a body mass index of 45 ± 4 kg/m2 were studied. 20 patients were active smokers (20 ± 12 pack years). All patients underwent preoperative lung functiontests. Arterial blood gases were collected before and after induction of anesthesia and either a single slice CT or a spiral CT was made for assessment of the amount of lung collapse. Respiratory system compliance was measured during anesthesia.Results: Lung volumes were within normal limits, however forced expiratory gas flow was reduced during the latter part of expiration. The arterial oxygen tension divided by the inspired O2 fraction (PaO2/FIO2 ratio) decreased from 409 ± 47 mmHg awake to 238 ± 80 mmHg after induction of anesthesia. The higher FEV1 was, the larger was the fall in oxygenation during anesthesia. At 5 min after induction, atelectasis in a CT cut 1 cm above the diaphragm was 7 ± 2 % of the lung area. The amount of atelectasis during anesthesia correlated with FEF75 in a regression analysis (p = 0.03).Conclusion: In morbidly obese patients without clinical signs of pulmonary disease a preoperative spirometry with mild signs of airway obstruction (reduced late expiratory flow) may predict reduced formation of atelectasis during anesthesia.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Anestesi och intensivvård (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Anesthesiology and Intensive Care (hsv//eng)

Nyckelord

Anestesiologi och intensivvård

Anaesthesiology and Intensive Care

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