Pulse oximetry at fibre-optic bronchoscopy in local anaesthesia: indication for postbronchoscopy oxygen supplementation?

Abstract

The requirement for supplementary oxygen (O2) after fibre-optic bronchoscopy (FOB) was evaluated by means of pulse oximetry in 34 patients (19 men) of median age 62 years (range 28-85) who had had a diagnostic FOB. The patients were allocated at random into two groups, each of 17 persons, which were comparable concerning sex, age and the dose of benzodiazepine (diazepam tablets 10 mg 1 h before FOB and midazolam 2-5 mg i.v. during FOB) used for premedication. Patients in group 1 had lower pulmonary function (FEV1, FVC as a percentage of predicted values) than patients in group 2 (P < 0.02). The oxygen saturation of the haemoglobin (SpO2) in the tip of the index finger was recorded continuously for 30 min after the administration of oral diazepam, during FOB and for 120 min after the FOB procedure. All patients received nasal O2 supplement 21 min-1 during FOB. After FOB, O2 was discontinued in group 1, while group 2 continued to receive O2 21 min-1 for 120 min. The incidence of hypoxaemic episodes (SpO2 < or = 90% for a period of a minimum of > or = 12 s) after oral diazepam, before FOB, was similar in the two groups, 35%. After FOB, the incidence of hypoxaemic episodes was 88% in group 1 and 41% in group 2 (P < 0.01). The cumulated duration of hypoxaemia after FOB was a median of 30 s (range 0-7140) in group 1 and a median of 0 s (0-156) in group 2 (P < 0.0001). Impaired lung function (FEV1 < 75% of predicted value) was a risk factor for hypoxaemia. Postbronchoscopy, O2 supplement should be administered to sedated patients with impaired lung function until the patients have fully recovered.