8.1 Assist with Bedside Procedures

Flexible Bronchoscopy in the ICU

Flexible bronchoscopy is frequently performed at the bedside in the ICU for both diagnostic and therapeutic purposes. As the airway expert, the respiratory therapist (RT) is responsible for managing the airway and the ventilator throughout the procedure.

Indications

• Therapeutic: Removal of thick, tenacious secretions or mucus plugs causing lobar atelectasis; removal of small foreign bodies; assistance with difficult intubations.
• Diagnostic: Bronchoalveolar lavage (BAL) to obtain lower respiratory tract cultures (especially for VAP or opportunistic infections like PCP); inspection of the airway for thermal injury, strictures, or tumors; obtaining biopsies or brushings.

Complications and Risks

The introduction of a bronchoscope into the airway significantly reduces the cross-sectional area of the endotracheal tube. A standard adult bronchoscope requires a minimum ETT size of 8.0 mm for optimal ventilation, though it can be passed through a 7.5 mm tube with increased airway resistance.

• Hypoxemia: The most common complication, caused by partial airway obstruction and V/Q mismatch during suctioning.
• Transient Bronchospasm: Mechanical irritation of the airways can trigger reactive bronchoconstriction.
• Bleeding: Following biopsy or in patients with coagulopathy (like DIC).
• Pneumothorax: A risk if transbronchial biopsies are taken near the lung periphery.

RT Role and Ventilator Management

Prior to the procedure, the RT must prepare the ventilator and the patient:

1. Oxygenation: Pre-oxygenate with 100% FiO2 for at least 10-15 minutes prior and maintain 100% throughout the procedure.
2. Ventilator Settings Adjustments: The bronchoscope will drastically increase airway resistance. If the patient is in a pressure-targeted mode (like Pressure Control or PRVC/Volume Control Plus), the set pressure may be reached instantly without delivering a tidal volume, leading to severe hypoventilation.
   • The RT should switch to a straight Volume Control (VC-CMV) mode to guarantee tidal volume delivery, or carefully adjust the pressure limits if remaining in pressure modes.
   • High pressure alarms must be increased, as peak inspiratory pressure (PIP) will inevitably spike.
3. Sedation and Paralysis: Ensure the patient is adequately sedated. In some cases, a short-acting paralytic (e.g., cisatracurium or rocuronium) is administered to prevent coughing and fighting the ventilator.
4. Bite Block: Place a bite block if passing the scope orally to protect the expensive equipment.
5. Adapter: Insert a specialized swivel adapter (Bodai port) into the ventilator circuit to allow passage of the scope without breaking the circuit seal.

Chest Tube Management

Chest tubes (thoracostomy tubes) are inserted to drain air (pneumothorax), blood (hemothorax), or fluid (pleural effusion) from the pleural space, restoring negative intrapleural pressure and allowing the lung to re-expand.

The Three-Chamber System

Modern chest drainage units are based on a three-chamber design:

1. Collection Chamber: Collects fluid directly from the patient. The RT monitors the rate and color of drainage.
2. Water Seal Chamber: Acts as a one-way valve, allowing air to escape the pleural space but preventing room air from entering. It is typically filled with 2 cm of sterile water.
   • Tidaling: The water level should fluctuate with respiration (rising during inspiration, falling during expiration in a spontaneously breathing patient; the opposite during positive pressure ventilation). Tidaling is a sign that the tube is patent and the system is intact.
   • Bubbling: Continuous or intermittent bubbling in this chamber indicates an air leak. If the patient has a known pneumothorax, intermittent bubbling on exhalation is expected. However, sudden, continuous bubbling suggests a leak in the system (e.g., a disconnected tube) or a large bronchopleural fistula.
3. Suction Control Chamber: Regulates the amount of negative pressure applied to the pleural space. In traditional wet systems, the height of the water column (usually -20 cmH2O) dictates the suction level, not the wall vacuum regulator. Gentle, continuous bubbling should be seen here if suction is active.

Troubleshooting Chest Tubes

• Sudden cessation of tidaling: If tidaling suddenly stops, the system is likely obstructed (e.g., kinked tube, blood clot) or the lung has completely re-expanded (which is good). Check the patient and the tubing.
• Excessive continuous bubbling in the water seal: Clamp the tube briefly near the patient's chest. If bubbling stops, the leak is inside the patient (e.g., bronchopleural fistula). If bubbling continues, the leak is in the tubing or drainage unit, requiring replacement of the system.
• Accidental Removal: If the chest tube is accidentally pulled out, immediately cover the insertion site with a sterile occlusive dressing (e.g., Vaseline gauze) taped on three sides to create a flutter valve, allowing air to escape but not enter, and notify the physician stat.