Positive Pressure During Bronchoscopy

Since its introduction in the late 1960s, fiberoptic bronchoscopy (FOB) has been increasingly used for diagnostic and therapeutic purposes. Because arterial oxygen tension (PaO2) usually decreases by 10 to 20 mm Hg after uncomplicated bronchoscopy, severe hypoxemia in nonintubated patients is an accepted contraindication to bronchoscopy. The American Thoracic Society recommends avoiding bronchoalveolar lavage (BAL) in spontaneously breathing patients with hypercapnia or hypoxemia that cannot be corrected to at least a PaO2 of 75 mm Hg or to oxygen saturation greater than 90% with supplemental oxygen (1). In these high-risk patients, the options are to intubate and to apply mechanical ventilation (MV) to ensure adequate gas exchange during FOB or to avoid FOB and to institute empirical treatment.

This limitation has prompted the development of techniques of respiratory support to make the FOB procedure safer for hypoxemic or critically ill patients, without using invasive ventilation.

It has been demonstrated the application of noninvasive positive pressure ventilation (NPPV) to assist spontaneous breathing through a face mask during FOB with BAL in severely hypoxemic, nonintubated patients (2). FOB was well-tolerated, significantly improved the PaO2/FiO2 ratio, and successfully avoided the need for endotracheal intubation. Two randomized studies have provided supporting evidence that the application of NPPV or CPAP via a face mask was superior to oxygen supplementation alone during FOB (3,4).

For this reason patients who require FOB and are hypoxemic and/or mild hypercapnic (TcCO2 < 60mmHg) will be compared in a randomized study by comparing NPPV vs CPAP Boussignac (Vygon) delivered through a face mask.

Methods Adult patients will be recuited in Bronchology Department and Intensive Care Units of the Hospital S. João, EPE. Only when inclusion criteria and a written informed consent of participation have been obtained from the patient, they will enter this study.

Before undergoing bronchoscopy all patients will be evaluate by SpO2, TCCO2, arterial blood pressure (ABP), heart rate (HR), respiratory rate (RR) and ECG. Patients with SpO2<92%, oxygen supplementation will be provided to achieve SpO2>92%. At this stage all patients will be randomly assigned to receive NPPV or CPAP Boussignac through a face mask during bronchoscopy. During the procedure, patients will be continuous monitored with ECG, ABP, HR, RR, SpO2 and TCCO2. These clinical parameters will be recorded at the following times: 1 - at evaluation; 2 - before the beginning of FOB; 3 - during FOB; 4 - at the end of FOB; 5 - 5, 15, 30, 60 min after FOB.

Inclusion criteria

• need for FOB;
• hypoxemia, defined by pulse oximetry (SpO2) >92% under oxygen supplementation;
• mild hypercapnia, defined by transcutaneous CO2 (PaCO2) <60mmHg;
• already under domiciliary NPPV.

Exclusion criteria

• emergent intubation;
• recent (less than 1 wk) acute myocardial infarction;
• ph bellow 7.30;
• PaCo2 > 60mmHg;
• systolic blood pressure < 80mmHg;
• encephalopathy or coma.