Low-Flow vs. High-Flow Nasal Cannula for Hypoxemic Immunocompromised Patients During Diagnostic Bronchoscopy

Pneumonia is a lung infection that is a common complication in people with cancer, because of a weak immune system. Fiberoptic bronchoscopy is a test that is commonly used to help doctors diagnose the type of lung infection and treat it appropriately. It involves passing a thin tube with a camera at the end inside the lungs, and taking some fluid samples which are sent for analysis. While this procedure is being performed, a small amount of oxygen is delivered into the nose (low flow nasal cannula). Occasionally during this procedure, the blood oxygen of the patient may drop (even if the patient is receiving oxygen, and especially if the patient has severe pneumonia), and the procedure may have to be interrupted or prematurely stopped. If the oxygen level drops significantly, an intervention such as increasing the oxygen flow, or in the worst-case scenario temporarily placing the patient on a breathing machine is required. An alternative device called 'Optiflow' can provide high flow oxygen through nasal cannula, and is comfortable for patients. Optiflow was approved by Health Canada in 2006, and is commonly used in hospitals in Ontario and around the world to support patients whose blood oxygen is low. If Optiflow is used during bronchoscopy, it may prevent the blood oxygen from dropping.

Inclusion criteria

• Adult patients ≥18 years scheduled to undergo FOB (as determined by their medical care team) who are immunocompromised (active hematologic malignancy or post hematopoietic stem cell transplant), and are hypoxic with pulmonary infiltrates. Hypoxia will be defined as requiring supplemental low flow oxygen ≥ 2L/min by nasal cannula to maintain SpO2 >90%.

Exclusion criteria

• requiring supplemental oxygen > 8L/min by nasal cannula;
• receiving HFNC before randomization;
• nasal deformity or packing precluding HFNC use;
• hypercapnia (PaCO2 > 60) or respiratory acidosis (pH <7.25);
• requiring NIV for over 1 hour or intubated.