Role of Bronchoscopy in ARDS
Bronchoscopy in ARDS patients should be reserved for specific diagnostic indications when less invasive methods have failed, as it carries significant physiological risks in this critically ill population and is not routinely indicated for standard ARDS management. 1
Primary Indications for Bronchoscopy in ARDS
Diagnostic Scenarios
Bronchoscopy should be performed when ARDS fails to respond to standard therapy and an alternative or superimposed diagnosis is suspected. 1, 2
Suspected ARDS mimics requiring specific treatment (acute interstitial pneumonia, organizing pneumonia, acute eosinophilic pneumonia, hypersensitivity pneumonitis, drug-induced lung disease) warrant bronchoscopy with bronchoalveolar lavage when clinical suspicion is high 3, 2
Suspected resistant or unusual pathogens in patients not improving after 72 hours of empiric therapy, particularly to identify Legionella, anaerobes, tuberculosis, fungi, and Pneumocystis 1, 2
Suspected ventilator-associated pneumonia in mechanically ventilated ARDS patients when non-invasive sampling is non-diagnostic 4
COVID-19 ARDS with suspected superinfection, where bronchoscopy identified secondary bacterial infections in 55% of cases and fungal infections in 14.3%, leading to management changes in 37% of patients 5
Therapeutic Indications
Mucous plugging causing lobar or complete lung atelectasis that impairs ventilation and oxygenation 4
Facilitation of difficult intubation or guidance of percutaneous dilatational tracheostomy 4
Critical Safety Requirements for Bronchoscopy in ARDS
Pre-Procedure Preparation
Increase inspired oxygen concentration to 100% before, during, and immediately after bronchoscopy. 1
Switch ventilator to mandatory mode (volume control or pressure control), as triggered modes (pressure support, assist control) will not reliably maintain ventilation during the procedure 1
Use a special swivel connector with perforated diaphragm to maintain PEEP/CPAP during bronchoscope insertion, which is particularly critical in hypoxic ARDS patients 1
Increase ventilator pressure limit to ensure adequate tidal volumes are delivered despite increased airway resistance from the bronchoscope 1
Increase ventilator rate if necessary to maintain minute ventilation 1
Equipment Considerations
The bronchoscope external diameter must be carefully matched to endotracheal tube size. 1
A 5.7 mm bronchoscope occupies 40% of a 9 mm endotracheal tube and 66% of a 7 mm tube, causing significant ventilation impairment 1
Use a bronchoscope with external diameter ≤4 mm in severe ARDS to minimize disruption of lung-protective ventilation 6
Bronchoscope insertion immediately causes either decreased minute ventilation or substantially increased PEEP (depending on inspiratory pressure limit settings), leading to increased plateau pressure that disrupts lung-protective ventilation 6
Monitoring Requirements
Continuous multi-modal physiological monitoring must be maintained during and after bronchoscopy, including ECG, continuous intra-arterial blood pressure (or intermittent cuff pressure), and pulse oximetry with appropriate alarm limits 1
Monitor tidal volume and minute ventilation continuously using modern microprocessor-controlled ventilators 1
Sedation Protocol
Unstable hypoxic ARDS patients require deep sedation, analgesia, or muscle relaxation to maintain oxygenation and prevent patient-ventilator dyssynchrony 1
Use synthetic narcotics (alfentanil or fentanyl) to suppress cough and provide profound analgesia 1
Induce sedation with incremental doses of benzodiazepine or propofol 1
Exercise caution with lignocaine in patients with renal failure, liver dysfunction, or congestive heart failure due to risk of accumulation and seizures 1
Alternative Approaches in Specific ARDS Scenarios
NIV-Supported Bronchoscopy in Mild-to-Moderate ARDS
Bronchoscopy can be performed under noninvasive ventilation in selected mild-to-moderate ARDS patients (PaO2/FiO2 >150) who are hemodynamically stable and cooperative. 7
In a prospective study of 28 ARDS patients (mean PaO2/FiO2 145), bronchoscopy under NIV was well-tolerated with only 17.9% experiencing minor complications 7
PaO2/FiO2 improved from 132 to 173 after the procedure, and no patient required intubation within 2 hours 7
Bronchoscopy provided diagnosis in 96.4% and led to treatment changes in 71.4% of patients 7
However, life-threatening complications in severe hypoxemia remain a significant risk 7
Open Lung Biopsy as Alternative
When bronchoscopy demonstrates no unusual or resistant organisms and the patient deteriorates despite appropriate therapy, consider bedside open lung biopsy. 2, 8
In mechanically ventilated ALI/ARDS patients, bedside open lung biopsy obtained specific diagnosis in 70% and led to treatment alterations in 81% of cases 8
Major complications occurred in only 7% with no procedure-related deaths 8
Open lung biopsy should be reserved for cases where diagnosis remains elusive despite comprehensive evaluation including bronchoscopy 2
Common Pitfalls to Avoid
Do not perform bronchoscopy routinely in ARDS, as the procedure carries significant physiological risks without clear benefit in standard cases 1
Do not use triggered ventilator modes during bronchoscopy, as they will not reliably maintain ventilation 1
Do not proceed with bronchoscopy using a large-diameter bronchoscope in severe ARDS, as this disrupts lung-protective ventilation and increases plateau pressures 6
Do not assume all bilateral infiltrates represent typical ARDS—maintain high suspicion for ARDS mimics requiring specific therapies rather than standard supportive care 3, 2
Immediately withdraw the bronchoscope and resuscitate if adverse events occur, then reassess the risk-benefit ratio before proceeding 1